Overview of the Conservation of Australian Marine Invertebrates

Executive Summary
Fauna & Places
Conservation General
Taxon Approach
Systems Approach
Threatening Process
Information Base


A threatening process is a process that detrimentally affects, or may detrimentally affect, the survival, abundance, distribution or potential for evolutionary development of a native species or ecological community (Burgman and Lindenmayer 1998). This approach to conservation deals mainly with the management of human impacts on the environment responsible for the decline of biota, rather than managing a particular habitat or group of organisms. For conservation strategies of any sort to succeed, it is essential that management of threatening processes goes hand in hand with other strategies, either taxon-based or habitat based systems.

While the immediate (“proximate”) threats to marine life have been highlighted and discussed in a number of documents, and are those most commonly dealt with because they are a manageable size, it should be emphasised that these are only aspects of the fundamental, underlying or root (“ultimate”) factors. Norse (1993) identified these root causes as:

  • There are too many people (population growth);

  • We consume too much (over consumption);

  • Our institutions degrade, rather than conserve biodiversity;

  • We do not have the knowledge we need; and

  • We do not value nature enough.

Threatening processes can be natural or anthropogenic and change the environment in ways that may jeopardise the continued existence of fauna in their natural role within their environment (Yen and Butcher 1997). While natural processes that threaten taxa or habitats are, by their very nature, part of natural evolution, these may be difficult to separate from anthropogenic changes (e.g., the current debate on global warming and sea level rise). Yen and Butcher (1997) did not consider natural impacts in their review, focusing entirely on anthropogenic threats, although they recognised that natural processes might be modified by these threats. We consider that, in some cases, the impacts of some natural changes are relevant when they are compounded by anthropogenic changes and some attempt should be made to manage them to prevent biodiversity loss. For example, habitat destruction may have reduced a particular habitat type to one small area and this may contain rare or threatened species. If storm damage destroys this last remaining piece of habitat, is this loss entirely natural as its loss is clearly the consequence of other anthropogenic threatening processes?

Most people now accept that anthropogenic changes to the earth and its atmosphere have resulted in climate changes (Section 6.7) notably in increased land and sea temperatures, increased incidence of storms and changed rainfall patterns. Several other potential threatening processes are apparently part of the natural system but which (some argue) may be partially caused, or at least exacerbated, by human activities. These include pathogens and diseases; population outbreaks; and algal or dinoflagellate blooms.

Another difficulty in assessing the effects of threats, or in determining the causes of observed declines, is that most marine ecosystems experience considerable natural spatial and temporal fluctuations in abundance, community composition etc. (see Section 7.7.1). Fluctuations may be attributed by a researcher operating in a particular place and time to some anthropogenic impact, but in fact it may be part of a natural cycle, a response to a natural process or event, or the result of a combination of factors. Without proper long-term baseline studies with controlled reference sites, there is little opportunity of actually assessing the impact. Yet, very few long-term studies of natural fluctuations of marine invertebrates have been undertaken.

While all marine ecosystems are exposed at various times to a range of ‘natural’ stresses ranging from predation to disease to natural ‘disasters’ such as storms and cyclones, or, in the sub-Antarctic, even iceberg impacts, these are essentially dynamic with a disturbance and recovery phase. Thus an ecosystem suffering a dramatic change caused by a natural disturbance should, other things being equal, eventually recover. However, human disturbances interact with natural stresses and can reduce the capacity of the system to recover from further impacts, thus producing chronic degradation.

Unfortunately, it is often difficult to distinguish between natural and anthropogenic processes when attempting to assess the causes for a decline in some systems. Natural disturbances may be physical (e.g., hurricanes, floods, earthquakes, low tides) or biological (e.g., diseases, outbreaks of predators). It is often not possible in practice to distinguish, for example, between the effects of climate change, of natural environmental variability, or of non-climatic anthropogenic alteration; effects may be interactive, or a single stress may have multiple sources (Smith and Buddemeier 1992). Natural impacts, such as cyclone damage to coral reefs (e.g., Van Woesik et al. 1995; De Vantier et al. 1996; Bythell et al. 2000) may be the result of direct impacts such as wave action or secondary effects, such as disease or from sediments carried by floodwaters.

While some threats may directly impact particular elements of the biota, especially by changing or destroying their habitat, others act indirectly (e.g., global warming, pollution). Not all threatening processes are obvious. Some may be quite subtle and insidious; for example, those causing sublethal effects that result in reduced fecundity, food supply, changes in skeletal density or gradual reduction in habitat. It should also be recognised that impacts from threatening processes may be cumulative and that several different threatening processes can act simultaneously.

Human impacts on marine environments are mainly concentrated on coastal habitats where the greatest human populations are located. However, in Australia, as elsewhere, the use of innovative technology is increasing the level of offshore mining, oil and gas exploration and deep-sea fishing, activities that could become an increasing threat to offshore marine communities. 

6.1       Pros and cons of the threatening processes approach

The threatening processes approach is important with respect to management action. The management of particular activities and threats by certain agencies is, in many cases, already well established (e.g., shipping, fisheries, pollution licences, etc). Conversely, some threats are not well controlled, sometimes due to inefficient or inadequate management. As with terrestrial environments, this is often because multiple agencies are involved, for example in various aspects of managing a particular habitat, area or activity. Managing agencies may be limited in their control of threatening processes that originate outside the area or sphere of activities under their jurisdiction. In the case of the Great Barrier Reef, where the entire system is nominally under the jurisdiction of a single managing authority (the Great Barrier Reef Marine Park Authority), there are relatively few options for direct action on threats that originate outside the designated area. For instance, the poor quality of terrestrial runoff has been identified as a key threatening process (Baldwin 1990; Bell 1991; Yellowlees 1991; Brodie 1995a, 1997; Hutchings and Haynes 2000), yet this is primarily due to actions by land owners and is therefore the responsibility of local councils, catchment management authorities and individual landholders, rather than the Marine Park Authority[109]. In cases where multiple agencies are responsible for different aspects of a system or activity, one authority may approve a development that results in some loss of habitat and be unaware of other developments in other parts of the system that fall under other jurisdictions. Thus habitat can be lost progressively by ‘the tyranny of small decisions'.


  • It is easier to manage or place controls on particular industries or types of users identified as causing one or more significant threats than to co-ordinate all the different threats facing particular species or habitats.

  • Well considered threat management can identify and focus upon processes that may result in severe consequences and threats if unmanaged. For example, strategies to minimise the importation of marine organisms in ballast water are much more likely to succeed than programs to eradicate existing marine pests.  Prevention is better than cure.

  • This approach allows some action to be taken without necessarily having detailed taxonomic or systems-level information.


  • Multiple threats are typically operating and it is often difficult to identify the most relevant.

  • Identification (or misidentification) of one obvious threat may ignore the cumulative or synergistic effects of other more subtle threatening processes.

  • Cost benefit, political or social considerations may be major factors and override ecological considerations (e.g., destruction of benthos by commercial trawling).

  • Management problems, including lack of coordination when multiple agencies are responsible, and inter-departmental rivalry.

  • There are logistical and political problems separating the threatening process from the agent of that process (e.g., coastal development is not a threatening process in itself, but because its implementation often results in a number of different threatening processes being realised, all such development is, perhaps incorrectly, considered a threat).

  • There is a need for enforcement, usually by way of legislation or regulation, in order to be effective.

  • Targeted management may ignore other threats (e.g., fisheries response to overexploitation is concerned with the protection of the resource, not the environment – e.g., impacts of trawling).

  • Regulations must be strongly enforced to be effective. Such regulations are often focused on particular suites of taxa (e.g., edible fishes and invertebrates, and species collected for use as bait), with little attention paid to activities that impact other taxa.

The listing of specific threatening processes in legislation (such as previously in the Commonwealth’s Endangered Species Protection Act 1992) has been problematic. This was seen as potentially the ESPA’s most important contribution, but the cases initially accepted concerned four terrestrial feral pests and one pathogen. Processes involving human action have been far more contentious (Woinarski and Fisher 1999). For instance, despite widespread acceptance that vegetation clearance is one of the most important factors contributing to loss of Australia’s terrestrial biodiversity (State of the Environment Advisory Council 1996), it was not listed, although it has recently been declared a key threatening process under the TSC Act in NSW. This was largely because a national plan was required and the cooperation of all states is necessary, and in this case agreement was unlikely. This criterion raised a barrier that can be used to prevent the listing of activities clearly detrimental to biodiversity (Woinarski and Fisher 1999). This situation has changed under the Environment Protection and Biodiveristy Conservation Act 1999 (EPBC Act) and, already several Key threatening processes have been listed (see Section 8.2.2).

6.2       Threatening processes – their relation to marine-based industries and activities

Many threatening processes relevant to marine ecosystems have been identified in the literature, ranging from discussions of general, broad scale issues and impacts on the marine environment in a variety of reports and popular books, to scientific papers examining the threats facing particular taxa, areas or habitats. Threats to the marine environment have been outlined in a number of key Australian government documents including the National Strategy for the Conservation of Australia’s Biological Diversity (Commonwealth of Australia 1996), Australia’s Oceans Policy (Commonwealth of Australia 1998a, 1998b) and State of the Environment Reports (e.g., Zann 1995; Zann and Kailola 1995; Zann and Sutton 1995;

State of the Environment Advisory Council 1996; Zann 1996; Australian State of the Environment Committee 2001). International publications include reviews of marine biodiversity and conservation by Norse (1993) and GESAMP (1997). For instance, the national State of the Marine Environment Report (Zann 1995) summarised major uses of the marine environment with potential impacts (recreation and tourism; fisheries; and marine transport and energy), as well as general issues and pressures (coastal modification; coastal development and sea level change; marine pollution; introduced species; and population outbreaks). In Victoria, Norman and Sant (1995), identified heavy commercial and recreational harvests of some species, destructive fishery practices, non-collecting visitation pressures, marine and coastal developments, eutrophication from sewage discharge, siltation, chemical pollutants and introduced biota as exerting pressures on marine invertebrates. From a global perspective, Norse (1993) identified five broad classes of threats to marine biodiversity (over-exploitation, physical alteration, marine pollution, introduction of alien species, and global atmospheric change), resulting from a range of human activities. GESAMP (1997) identified habitat degradation and fragmentation, climate change, UV radiation, fishing, pollution, litter, non-indigenous species and the impact of tourism as significant threats. In a review of literature relevant to the conservation of shallow tropical marine ecosystems, particularly coral reefs, mangroves and seagrass communities, Hatcher et al. (1989) included anthropogenic impacts such as sedimentation, chemical pollution, sewage pollution, thermal pollution, radioactive pollution, hydrodynamic influences, physical disturbance, extractive industries, introductions and tourism. Suchanek (1994) reviewed threats to temperate coastal marine communities and identified (1) habitat loss and degradation, (2) pollution (from numerous sources including sewage, pesticides, pulp mills, thermal effluents, polychlorinated biphenyls, heavy metals, oil and radionuclides), (3) over-exploitation, (4) species introductions, (5) global climate change, (6) misguided human perceptions and (7) legal complexities as the most significant categories of threats.

In many cases these discussions only partially separate the actual threatening processes (i.e. impacts which affect marine organisms, e.g., marine pollution, introduced species, population outbreaks) and the agents or activities responsible for those impacts (fishing, shipping, development etc.). However, it can be important to distinguish between processes and agents, as many activities result in a variety of impacts while many impacts can have a range of contributing causes. For example, direct exploitation through fishing is often considered a threatening process, but if harvest levels are sustainable, fishing is not necessarily a threat to the harvested species. On the other hand, it could result in other threats (e.g., habitat damage). Consequently, we have divided this chapter into two parts, dealing with the processes (the threats) and the agents (the causes of the threats).

Table 6.1 lists some of the direct impacts associated with each industry or activity (i.e., agent) responsible for the threats (ie., threatening processes), and illustrates the relationships between the various categories of threats and industries/activities. Most of these processes have direct and indirect, lethal or sub-lethal, effects on invertebrate communities and ecosystems in general, including changes to community structure and composition, alteration of trophic structures and food webs, etc. While some of these are discussed where appropriate under each agent, any threatening process that alters habitat, inputs of nutrients or pollutants, introduces new biota, etc., is likely to have 'knock-on' effects. 

For instance, exploitation of a particular species may reduce the populations of non-target species to below the density needed to sustain their populations. Exploitation may also affect community structure and competitive interactions if key predator or herbivore species are targeted. Thus some threatening processes may affect particular taxa or suites of organisms directly (e.g., harvesting, toxic pollution, etc.) while others may affect some biota indirectly through alterations to their habitat, or through changes in community processes or structure. 

The potential for synergistic effects, involving two or more different threatening processes, cannot be over emphasised. Similarly, cascading effects – where one threatening process leads to another – are also important. Both synergistic and cascading effects are discussed in more detail in Section 6.9 below.

While there is good information on some of the major threatening processes and their impacts on marine invertebrates a considerable amount is unknown and can only be surmised. In many cases the only well documented examples are non-Australian, although we have included information from Australian studies where possible.

Table 6.1: The main industries and activities associated with impacts on marine invertebrate fauna and examples of the types of impact that may occur under each of the major categories of threatening processes.


In line with Norse (1993) we recognise five major categories of threatening processes for marine invertebrates:

1.        Direct exploitation;

2.        Physical damage or alteration (including habitat destruction)[111];

3.        Pollution;

4.        Introduction of non-indigenous species;

5.        Long-term climate change.

These differ from the five processes identified by Yen and Butcher (1997) for non-marine invertebrates in that their separate categories of habitat destruction and alteration are combined, and pollution is included as an additional category.

Although each of these categories can be considered independently, they are often correlated. For example, reclamation of mangroves not only destroys habitat but results in the incidental death of the organisms living there at the time and increases the likelihood of pollution by the loss of the filtering effects of the mangroves, leading to damage of adjacent seagrass beds and saltmarsh. In addition, the same threatening process can be the result of several different human activities.

In addition to these major categories, we include some discussion of threats with complex, unknown or debated origins, including diseases, parasites, and population outbreaks of destructive or “pest” species. These have been variously attributed to natural and anthropogenic causes or to some combination of these. Even if entirely “natural” in origin, they may achieve “unnatural” significance in areas already stressed or degraded by a variety of anthropogenic activities, and thus it is important that they also be given consideration.

Most of the above categories of threatening processes can be subdivided into primary and secondary processes (see below). Some of these processes can be associated with the main maritime industries and other uses of the marine environment; others (e.g., pollution, climate change) primarily result from human impacts in the terrestrial environment.

6.3       Overexploitation

Many marine invertebrate species are harvested, commercially and recreationally, for a variety of uses including food, bait, and ornament (see Sections 3.2.7 and 6.10.3). Economically important marine invertebrates include the many species harvested as “seafood” (e.g., molluscs such as oysters, scallops, abalone, and squid; crustaceans such as lobsters, prawns, and crabs; and holothurian echinoderms – trepang or bêche de mer), as well as species harvested for bait (worms, intertidal molluscs, crustaceans and ascidians or“sea squirts”), those collected for their use in collections, jewellery or other ornament (shelled molluscs, coral, some echinoderms and crustaceans), and species collected live for the aquarium trade (corals, molluscs, anemones etc.). Direct exploitation of marine invertebrates for human food is a major industry in Australia, the total catch in 1997-98 being at least 83 Mt and worth more than A$1.3 billion (ABARE 1998; see also Section 3.2.5).

Exploitation does not by any means always constitute a threatening process, and may be sustainable provided the rate of removal does not exceed the reproductive potential of the species, and the impact is not compounded by other effects such as habitat damage. There are many documented examples of marked declines due to overexploitation of populations or entire species of marine invertebrates, a few being detailed below (Section 6.3.2). Here we discuss the various effects of overexploitation, ranging from population decline, reproductive failure and change in population structure of targeted species, to changes in community structure and trophic interactions resulting from the removal of key predator or prey species. There are also a range of accidental, indirect and secondary effects that may result from the techniques or gear used to harvest marine species. These, including the accidental capture of non-target species (bycatch), and damage by fishing gear to individuals or habitats (e.g., trawling), are discussed in Section 6.10.2.

6.3.1          Effects of exploitation on target and non-target species and communities

This section deals with the effects of overexploitation on target species – both directly induced declines and those brought about indirectly through (for example) critical reductions in population density – and the effects of this removal of biomass on the communities and ecosystems of which the exploited species form a part. Other impacts of fishing not directly related to the effects of overexploitation (e.g., habitat damage from trawl gear) are dealt with later in the section on Fisheries (Section 6.10). 

6.3.2    Examples  - effects of exploitation on target species

In the following section we provide a brief discussion of several specific examples, from both commercial and semi-commercial or recreational fisheries, to illustrate some of the effects over exploitation can have on targeted marine invertebrate species, and the conservation and management issues that arise. These examples are not exhaustive and the issues involved are generally applicable to a number of fisheries. For a discussion of the different types of fisheries (commercial and recreational), together with their “accidental” or secondary effects and management options, see Section 6.10.

6.3.3    Information, research needs and management

It is difficult to evaluate the degree of threat posed from harvesting for most marine invertebrates because there is a need for :

  • Accurate catch data (both professional and amateur);

  • Knowledge of species biology, population genetics, structure and size;

  • Historical data;

  • Suitable reference areas for comparison of exploited with unexploited populations; and (in some cases) certainty of taxonomic status.

In Australia, accurate figures on commercial landings of invertebrates are notoriously difficult to ascertain. Landings at fish co-ops are probably always underestimates, as fishermen may sell some of their landings privately, and may also underestimate their landings as these figures are used for management and tax purposes. Data do not usually provide information about where individual species are caught, nor any estimate of the time or effort taken to land the catch, making accurate estimates of increases or decreases in landings per unit effort virtually impossible. In the case of some fisheries (e.g., prawns and squid), several species may be included under one heading making species-level analyses impossible. The situation is infinitely worse with amateur fishing.

Pauly (1995) has argued that we have little idea of the full extent to which fisheries have reduced populations of marine species, even high-profile non-target species like mammals, because we have no proper baseline against which to judge declines. Without control areas, it is very hard to gauge the true impact of fishing of extant populations. In addition, it is apparent that many invertebrates have large natural population fluctuations, making it difficult to determine whether these populations are “declining” due to harvesting or whether catch levels are sustainable. Better knowledge of the biology, ecology and population dynamics of such species can assist in modelling responses to, for example, environmental variables, and thus predicting stock levels and setting TACs. Such models have been developed for prawns (e.g., Rothlisberg et al. 1985; Staples et al. 1995; Wang and Die 1996) and have been moderately successful (Caton et al. 1998).

The systematics of some commercially important taxa is uncertain. This has important ramifications when dealing with translocation of breeding stocks, comparison of fisheries data etc. Some examples from commercially important bivalves illustrate this point.

  • The commercially fished species of scallop (Pecten) may be a single species in temperate Australia or may consist of a species complex. Its relationships with a very similar commercial ‘species’ in New Zealand are also unresolved.

  • The valuable eastern Australian rock oyster (Saccostrea) fishery is largely based on a species that has had a confused taxonomic history. For many years it was thought to be a separate species from the northern New Zealand rock oyster but is now thought to be conspecific. However, its relationships with similar populations in other parts of Australia and the Indo-Pacific have yet to be resolved.

  • The NSW pearl oyster (Pinctada) has been shown to consist of two very similar species, one of which is conspecific and genetically very similar to the commercially valuable Japanese pearl oyster (Colgan and Ponder in press).

6.4       Physical damage / habitat alteration and loss

In the terrestrial environment, the issue of habitat destruction has received a great deal of attention, and is frequently considered the primary threatening process for the majority of terrestrial animals and plants (e.g., Glanznig 1995; Yen and Butcher 1997). Habitat destruction also is a serious issue in marine ecosystems (e.g., GESAMP 1997). Whilst habitat damage is most obvious in the coastal fringe, it is not confined to this zone, with fishing activities having also caused considerable modification of habitats in shallow sublittoral areas in harbours, bays and coastal areas, as well as on the continental shelf and slope (Watling and Norse 1998b; Jackson et al. 2001).

Physical damage and loss of habitat in the marine environment directly results from human activities such as trawling, dredging, mining, ship groundings, anchor damage, and (on a smaller scale) recreational uses such as reef walks and SCUBA diving. However, habitat modification can also be an indirect or secondary consequence of storms and other natural events, or changes (natural or human-induced) to water quality, hydrography, or community structure and ecological interactions. The specific effects of each relevant human activity or industry are discussed separately in sections 6.10 – 6.17. Trawling is undoubtedly the primary form of physical disturbance for soft-sediment marine benthic communities and has been likened to the clear felling of forests (Watling and Norse 1998b). In this chapter, the impacts of trawling are is discussed in section 6.10.2 and the other activities listed above are discussed in the following sections. This section briefly outlines the various forms of habitat alteration, fragmentation and loss, evidence for their effects on marine invertebrates, and the research needs relating to these as threatening processes.

6.4.1    Effects of physical damage and habitat alteration

6.4.2          Examples – effects of habitat loss in marine ecosystems

The conservation issues associated with various marine habitats have already been summarised in Chapter 5. Some brief examples relating to two key habitat types are given below to illustrate the diverse problems associated with habitat destruction and fragmentation.

Unlike many of the highly visible changes in coastal marine ecosystems, changes to benthic habitats in the deeper sublittoral, continental shelf and slope zones are ‘invisible’ and hidden from public or political attention. There are several activities that impact locally on these habitats including sewage disposal from ocean outfalls (Section 6.6.1), the dumping of rubbish at sea (Section 6.6.1), shipwrecks, pollution from oil and cargo (Section 6.12), offshore oil exploration and mining (Section 6.13), etc. There are also significant impacts in particular areas from scallop dredging (Sections 6.3.2; 6.10.2). By far the most significant and widespread impacts, however, result from trawl fishing (Section 6.10.2).

Coastal wetlands such as mangroves, seagrasses and saltmarshes are highly productive and important as nursery grounds for a large range of species (e.g., Nagelkerken et al. 2001). However, their location in sheltered bays and estuaries has meant that large areas of these habitats have been destroyed or heavily impacted, so that their maintenance is a critical issue in Australia and elsewhere. Destruction or alteration of vegetated habitats occurs not only through deliberate clearing and filling (e.g., mangroves – see Section 5.3.2) or dredging, or as an unintentional secondary impact of activities such as trawling (see Section 6.10.2), but also through more subtle long-term processes such as water quality decline, siltation, disease, and changes to hydrographic and climatic regimes.

6.4.3          Information, research needs and management

Habitat alteration and destruction is probably the most serious of all the threatening processes. Its causes are numerous and are dealt with under each of the agents responsible (fishing, including trawling, Section, 6.10.2, construction of aquaculture facilities, Section 6.11.1, shipping accidents, Section 6.12.1, petroleum drilling, mineral extraction and sand dredging Section, 6.13, recreational activities, Section 6.14 and coastal development, Section 6.16).

In order to assess habitat loss or reduction we need to consider the impacts resulting from two different spatial factors:

  • Reduction in, or loss of area; and

  • Increased separation.

Better information is needed to assess the extent of habitat loss. The extent of the habitat of interest, in all probability, will not have been previously surveyed. At best, the data will be patchy and inadequate. The impact of the loss or reduction of particular patches of habitat and their increased separation will vary considerably amongst taxa depending on their ecology and biology (e.g., dispersal abilities; needs at different parts of life cycle; food and feeding etc.). In most instances, there is insufficient ecological and biological information to make even crude predictions of potential impacts.

Experimental studies are needed to assess the likely impacts resulting from habitat fragmentation. These particularly need to address maintenance of taxon diversity and recruitment success.

Genetic studies are needed across various invertebrates exhibiting a wide range of reproductive strategies so that a clearer indication of the spatial extent of significant genetic structuring can be obtained.

6.5       Introduced  (non-indigenous) species

Human movements over the past 2000 or more years have altered the global distributions of many species dramatically and marine species are no exception. While pre-19th century distributions are often held to be ‘natural’, many marine invasions did occur prior to this time (Carlton 1999). Species have been introduced, both accidentally and deliberately, by many means including vessels (hull fouling, ballast, and sea chests), aquaculture, the aquarium trade, and intentional and accidental releases into the wild (Carlton 1987; Carlton 1999). Reviews on marine invertebrate introductions (Carlton 1987; Barber 1997; Carlton 1999) give examples where considerable economic damage has occurred, as well as documenting the degradation of natural ecosystems, following introductions of invasive species. It is also likely that introduced species carry with them both internal and external parasites that may not be host specific and could impact on native species (I. Whittington pers. comm.).

The worldwide interest in introduced species and the potential for these species to become pests (Mack et al. 2000), has led to predictions as to which species have the potential to become invaders, and the characteristics of these invading species (Kolar and Lodge 2001). By reviewing the literature, Kolar and Lodge have found that there are consistent patterns and statistically identifiable relationships between success in invasion transitions and characteristics of release events. They suggest these models may help natural resource managers to predict future introductions and reduce their occurrence and impact. Mack et al (2000) suggested that failure to address the issue of biotic invasions could effectively result in severe global consequences, including fishery resources in some regions, disruption of the ecological processes that supply natural services and the creation of homogenous, impoverished ecosystems composed of cosmopolitan species.

A meeting of scientists and lawyers provided decision-making guidance to policymakers, managers, scientists, and other stakeholders regarding alien marine species. The framework consists of seven basic steps: 1. Establish the nature and magnitude of the problem; 2. Set objectives; 3. Consider the full range of alternatives; 4. Determine risk; 5. Reduce risk; 6. Assess benefits versus risks; and 7. Monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and could provide a foundation for international co-operation (Bax et al. 2001).

Deliberate introductions into Australian waters have occurred mainly for the purposes of aquaculture, the Pacific Oyster (Crassostrea gigas) being a good example. Accidental introductions into Australian waters are far more widespread and have occurred by a variety of methods, including hull fouling, ballast water, sea chests and attachment to marine debris that has floated onto our coasts. While the advent of transport by ballast water (Hutchings 1992a) is a relatively recent phenomenon, the other methods of transport have been going on for centuries.

It is often extremely difficult to distinguish between native and introduced species, particularly in countries such as Australia where the native fauna is poorly known. Nevertheless, it is clear that there are many introduced marine pests in Australian waters. Likewise, while there are still no detailed inventories of the fauna for most Australian ports, although this is improving as port surveys for international ports around Australia are being carried out, there is little doubt that the number of introductions is increasing.

Pollard and Hutchings (1990) reviewed the species that had been introduced into Australian waters and attempted to identify the likely mechanisms and timing of each introduction. Species were only listed if material had been deposited in a museum and the identifications confirmed by relevant specialists.  CRIMP (CSIRO’s Centre for Research on Introduced Marine Pests) has recently estimated that more than 250 non-indigenous marine species have now been identified in Australian waters (Thresher 1999; R. Thresher pers. comm.). Furlani (1996) presented annotated descriptions of 70 of these listed introduced species to facilitate their recognition. Increases in the number of known introductions are largely the result of the considerable effort that has been expended during this period by CRIMP and others in undertaking port surveys to detect introductions. Port Phillip Bay, Victoria is by far the best-studied area to date.

Vectors for translocation of non-indigenous taxa

6.5.1    Effects of introduced species on native species, communities and ecosystems

Impacts caused by introduced taxa are not limited to fauna but also affect marine plants and algae, as well as whole communities and processes. In addition, introduced species may benefit some organisms, be detrimental to others of be neutral. Here we focus on the negative impacts.

The introduction of non-indigenous species can lead to predation or competitive and spatial interference with native species (Galil 1994). Some introduced species have obtained pest status due to their numerical and ecological dominance and/or economic impacts, and have succeeded in alienating large areas of habitat (e.g., extensive beds of the Giant Fanworm Sabella spallanzanii in Port Phillip Bay; large aggregations of predatory Northern Pacific Seastar, Asterias amurensis, in the Derwent Estuary and Port Phillip Bay). Such outbreaks clearly have a significant impact on native species, community structure and function, and probably, ecological processes.

A recently published study (Wilson et al. 1998; Hewitt et al. 1999) on the changes in benthic communities in Port Phillip Bay between 1969 and 1995 revealed that polychaetes have become more abundant than crustaceans and molluscs and that the proportion of suspension-feeding organisms has increased at the expense of deposit feeders. Introduced species (of which they identified 165 in all major plant and animal groups) and changes in nutrient input, were considered primarily responsible for these changes. However, it was difficult to separate the impacts due to introduced species and reduced nutrient loading associated with reduced discharge from Melbourne’s sewage treatment works. Similarly, Currie and Parry (1999) evaluated changes in the structure of benthic communities in Port Phillip Bay over 20 years by comparing results of a survey of 86 sites in 1969-72 with a survey of 13 sites in 1991-92. The species composition of communities differed significantly between surveys. Of particular concern was the establishment and abundant spread of a further three non-indigenous species (Sabella spallanzanii, Corbula gibba, Euchone limnicola) contributing to long-term and possibly irreversible changes to the ecology of Port Phillip Bay (Currie and Parry 1999; Talman et al. 1999; Cohen et al. 2000; Currie et al. 2000; Talman and Keough 2001). 

Hutchings (1999b) laments that much of the work over the last decade has simply documented the distribution and abundance of introduced species in Australian waters, with little effort at trying to ascertain the impact of introduced species on the native fauna (see note below). There are some exceptions: the impact of the Northern Pacific seastar, Asterias amurensis, on the benthos of the Derwent in Tasmania has been documented in a qualitative way (Grannum et al. 1996; see below). In addition, much of the concern about the impact of these species has focused on their potential economic effects (e.g., aquaculture losses, biofouling), rather than the damage to native marine communities.

6.5.2          Examples of introduced marine species

6.5.3          Information, research needs and management

An update on the status of this program is available at http://www.ea.gov.au/coasts/imps/index.html.

6.6       Pollution

While it has long been assumed that the oceans are too vast, and their dispersive and degradative powers too great, for the various forms of waste disposal and pollution to have any discernible impact, there is increasing evidence that this is not the case. Many marine habitats, particularly those in estuaries and coastal zones close to human population centres, are suffering a range of impacts resulting in a deterioration of the habitats and the communities found in them (e.g., Glasby 1997; Koop and Hutchings 1997b; Connell and Glasby 1999; Glasby and Connell 1999).

Sources of marine pollution may be classified as point source or diffuse. Point sources include all forms of direct discharge into the marine environment, whether through deliberate waste disposal[118] or accidental spills, such as from sewage outfalls, paper mills, factories, abattoirs, gravel washing plants, dredging activities, mining, ships and power stations (NSW Fisheries 1998a). Diffuse sources are generated from a variety of activities on land and carried as catchment runoff to the sea via watershed streams and ground water, or from atmospheric sources through winds and rain. Terrestrial runoff can include pesticides, herbicides and fertilisers from agricultural areas; animal wastes from farms and feedlots; sediments as a result of erosion following land-clearing, development or construction work; and urban stormwater containing a range of household and garden chemicals, oils, faecal material, rubbish etc.

The causes and effects of water pollution in Australia, including the behaviour of chemicals in aquatic systems, pollution ecology, and effects of various classes of pollutants, have been reviewed by Connell (1993).

6.6.1    Effects of different types of pollution

Pollution may impact directly upon individual organisms, causing mortality, physiological stress or reproductive impairment, either immediately (e.g., through acute toxicity or smothering) or through cumulative effects (e.g., bioaccumulation of heavy metals or organochlorines). The vulnerability of some plant species (particularly seagrasses) to certain types of pollution (e.g., siltation, turbidity, or chemical pollutants) may result in significant habitat changes or losses. Indirect or secondary effects can include changes in community composition and function (e.g., by selecting for pollution-tolerant species or certain trophic groups, such as filter-feeders) or effects on the health or survival of predatory species.

The major types of marine pollution, and their effects, are:

  • Toxic substances (e.g., organochlorine, PCBs, heavy metals, acids, radioactive wastes etc) – can cause direct poisoning and an array of secondary or cumulative effects;

  • Excessive nutrients – can result in eutrophication, leading to changes in communities, algal blooms, increased Biological Oxygen Demand (BOD);

  • Sediments – siltation and sedimentation can result in smothering, substrate change, clogging of gills, reduction in light and consequent loss of vegetation;

  • Oil and petroleum – spills can result in smothering of benthic organisms, and toxic effects from both the dissolved fraction of the oil and the chemicals used to clean it up;

  • Rubbish – can be responsible for smothering, tangling, choking etc. of larger organisms, but may also provide useful habitat for many invertebrates.

There are also complex mixtures, such as sewage, which can contain many or all of the above components and have a range of effects.


Oil and petroleum



6.6.2          Information, research needs and management

6.7       Long-term environmental change

The effects of global warming due to anthropogenic activities are becoming increasingly well documented. For the marine environment, potential effects are increases in sea level, temperatures and storms (Ray et al. 1992; Reid and Trexler 1992; GESAMP 1997; IPCC 1998; US EPA 2000). Despite the increasing evidence that sea and atmospheric temperatures are rising (e.g., Hughes 2000), global warming is still not universally accepted. There is a range of information available on global warming scenarios, potential impacts and management on several websites, including the US Environmental Protection Agency’s global warming site and the homepage of the Intergovernmental Panel on Climate Change.

6.7.1          Potential effects of global warming and climate change on marine invertebrates and their habitats

The potential effects of global warming were noted above. The potential impacts of these changes on marine organisms include:

  • Direct effects of increased atmospheric CO2 on some biological processes (e.g., coral calcification, photosynthesis by phytoplankton);

  • Direct effects of increased sea temperature on survival of species living close to their upper thermal limit (e.g., coral bleaching);

  • Changes in the distributions of species, resulting in changes to local invertebrate communities through the local disappearance or decline of taxa and the introduction of new taxa;

  • Loss (or alteration) of low-lying coastal habitats as a result of rising sea level and increased storm frequency.

  • Consequent creation of ‘new’ habitats as sea level rises.

In each of these cases, the responses by human communities may comprise an additional and significant threat to habitat and invertebrate populations. These would result from increased coastal modification by humans (beach works, seawalls etc.) to minimise the damage to human habitations and infrastructures.  

6.7.2          Ozone depletion and UV radiation

The decline in stratospheric ozone at high and mid latitudes has been correlated with increases in biologically damaging ultraviolet-B radiation (UVBR). The effects of increased UVBR on natural ecosystems have not been adequately assessed, although it has (rightly or wrongly) been implicated in the decline of invertebrates in freshwater ecosystems (e.g., Bothwell et al. 1994; Karentz et al. 1994) and frogs at high altitudes (Blaustein et al. 1994). The majority of marine organisms in deeper or more turbid waters are unlikely to be affected, due to the attenuation of UVR in the water column. UVB, however, does have the potential to damage DNA and chromatophores of marine plants and animals as deep as 20 m in clear oceanic waters and epibenthic invertebrates in shallow tropical waters (Hovel and Morgan 1999). The significance of this threat will depend not only upon the rate of ozone depletion (which is expected to peak soon and recover to pre- ozone depletion levels over the next 50 years; Brown 1997), but also any changes in climate patterns brought about through global warming. These later changes may affect the amount of UV reaching the surface, for instance through increased cloud cover (Brown 1997).

Marine organisms have evolved to live in a wide range of habitats and those on coral reefs are functionally adapted to extreme tropical conditions. Many groups of organisms living on reefs have developed efficient defences against potential damage from chronic solar exposure. This protection includes the elaboration of natural UV-absorbing compounds (sunscreens) and other mechanisms such as antioxidative enzymes and small molecule antioxidants. This has led to the synthesis of the UV absorbing compounds and their trailing as sunscreens for humans and in other applications (Dunlop et al. 1999; Shick and Dunlop 2002).

The relatively few studies on the effects of UV radiation on marine invertebrates have focused on corals, which are likely to be vulnerable given that they occur exclusively in clear, shallow tropical waters. 

6.7.3          Examples – effects of global climate change on marine communities

We discuss in more detail below the impacts of global climate change on two important communities: coral reefs and saltmarshes.

6.7.4    Information, research needs and management

Climate change (and its causes) is potentially one of the most serious of the threatening processes and cannot be dealt with on an industry-by-industry basis but requires multifaceted national and global programs and solutions.

  • To ensure the conservation of coastal biodiversity global warming must be slowed as much as possible.

  • Steps must also be taken to establish coastal zone policies that allow adaptive responses to rising seas by making way for the shoreward movement of coastal ecosystems as sea level changes.

Research into the likely impacts of rising sea levels and both atmospheric and oceanic warming is needed so that effective forward planning can be undertaken to alleviate, where possible, the impacts.

International and national management programs

6.8       Problems with complex, unknown or debated origins

6.8.1          Diseases and parasites

In a review of this issue, Harvell et al. (1999) discussed climate links and anthropogenic factors and emerging marine diseases. They noted that in the past few decades there has been a worldwide increase in the reports of diseases affecting marine organisms.

Epidemiologists recognise an interrelationship between:

  • Host (reduced health, increased susceptibilities);

  • Disease (new virulent strains);

  • Environment (modifies existing host-pathogen interactions).

Thus, while disease is a natural phenomenon, its incidence can be facilitated by human perturbation, for instance through:

  • Environmental changes that reduce the health of individuals or populations making them more susceptible to disease and/or parasites;

  • Introduction by human activity of diseases or parasites not previously found in an area (e.g., through deliberate or accidental introduction of hosts or vectors);

  • Human activities that result in the emergence of new, more virulent strains of diseases (eg. the use of antibiotics in aquaculture).

Diseases in the marine environment

6.8.2          Population outbreaks of invertebrate predators or grazers

Occasional outbreaks of species occur, some apparently "naturally", others probably as a result, directly or indirectly, of human disturbance. Many such population explosions may have little impact and largely go unnoticed. Others can have quite devastating impacts. Outbreak species typically involve invertebrates, but others that pose a significance threat in marine habitats include some dinoflagellates. The most publicised invertebrate involved in sporadic outbreaks has been the destruction of living coral by the Crown-of-Thorns starfish on the GBR and other parts of the Indo-west Pacific, although the whelk Drupella in WA, another coral eater, is also receiving some attention. Both of these are described in more detail below. Although there has been much debate over the causes of these outbreaks, with anthropogenic factors ranging from overfishing of predator species to increased pollution being blamed, some are probably, at least in part, natural boom-and-bust cycles. Problems with outbreak species arise when the prey has limited opportunities for recovery, recruitment, recolonisation, or dispersal compared to undisturbed ecosystems. That is, pressure from the effects of these species (e.g., grazing, predation etc.) is compounded by other, often anthropogenic, pressures on the species or ecosystem. 

6.8.3          Red tides (dinoflagellate blooms)

Worldwide there has been an increase in the frequency and extent of blooms of harmful marine microalgae and heterotrophic dinoflagellates (Burkholder 1998). The reasons for these blooms are poorly understood. Many taxa of “red tide” dinoflagellates appear to increase under suitable environmental conditions and independently of any human influences (Burkholder 1998). These environmental conditions may include strong salinity and temperature stratification in the upper layer and a bloom in the phytoplankton or diatom food source (e.g., Cloern et al. 1994; Crawford et al. 1997). On the other hand, some newly discovered toxic or otherwise harmful taxa have been correlated with anthropogenic factors such as eutrophication in poorly flushed areas such as estuaries and coastal waters (Burkholder 1998). Outbreaks of certain warm-optimal species have coincided with El Niño events, suggesting that warming trends in global climate change may stimulate their growth and extend or shift their range (Burkholder 1998). Another important human influence is transport. In the late 1980s, various exotic dinoflagellate species, both toxic and non-toxic, were discovered in ballast water, and subsequently in Australian harbour waters and sediments (Hallegraeff and Sumner 1986; Hallegraeff et al. 1990; Hallegraeff and Bolch 1991). Of particular concern was the discovery of a group of dinoflagellates that can produce paralytic shellfish poisoning (PSP), as these species have the ability to produce resistant resting spores that can be easily transported in ballast water sediment (Hallegraeff et al. 1988). PSP affects people who consume contaminated seafood. For instance, Hallegraeff and Bolch (1991) reported that among 80 cargo vessels that were sampled by Quarantine officers as they entered Australian ports (1987-1989), 40% contained viable dinoflagellate cysts and 6% carried the cysts of the toxic dinoflagellates Alexandrium catenella and A. tamarense (up to an estimated 300 million cysts per ship).

Some other dinoflagellates secrete toxins that can result in massive fish and invertebrate kills. In addition to direct toxic effects, these blooms – like those of other microplanktonic species – can also harm other marine species through local depletion of oxygen resulting in zones of hypoxia or anoxia. In addition to acute or lethal effects, accumulating evidence indicates that there may be substantial sublethal and chronic impacts to both marine species and human health from these organisms, such as long-term behavioural alteration, increased susceptibility to cancers and other diseases, depressed appetite, and impaired reproduction (Burkholder 1998). For some harmful species, there may also be significant indirect impacts resulting from habitat loss or disruption of the microbial food web balance (Burkholder 1998).

6.8.4          Information, research needs and management

The causes of population outbreaks of marine species are poorly understood and urgently require study.

  • Studies on the basic biology, ecology and distribution of at least keystone taxa would greatly improve the knowledge base so that at least basic information was available when required. For example, although much research has been carried out on Acanthaster, the reasons for population outbreaks in this taxon are complex and/or variable and remain poorly understood.

Dinoflagellate blooms pose a major threat to the aquaculture industry due to their risk to human health. They can be very effectively transported in ballast water as they encyst and can survive long periods in dark, hypoxic waters.

  • We know relatively little about the species of dinoflagellates that occur naturally in Australian waters, let alone the potential dangers of these taxa if they bloom. The early recognition of problematic or exotic taxa is also rendered difficult because there are very few people undertaking research on these organisms.

There is very little information available regarding diseases of marine invertebrates, other than for a small number of commercial species. Monitoring is almost solely limited to a few commercially important taxa. There is scant information on what diseases are present, let alone how to control them.

  • This issue raises important questions regarding the translocation of aquaculture stock.

  • There is a considerable risk that the introduction of exotic species (either as pests or for aquaculture) will bring with them undetected diseases that could affect native species.

6.9       Synergistic / cascading effects of multiple threatening processes

The effects of individual stresses or processes may be studied in isolation in the laboratory or staged manipulative field experiments, but it is often difficult to generalise the results of these experiments to the natural environment, where several stresses may be acting simultaneously.

It is also possible for two or more processes to have opposing (when two processes largely negate each other) and neutral (when two processes do not interact) effects or do not interact. In contrast, synergism is when the effect of two or more processes combined is greater than the sum of the individual effect.

The potential for synergistic effects, involving two or more different threatening processes, cannot be over emphasised and is probably a common situation in natural and disturbed systems. Synergism occurs when two or more processes work together simultaneously to great effect, unlike indirect or secondary impacts in which processes occur sequentially. Two examples are given below.

6.9.1    Information, research needs and management

Recognition of synergistic effects is critical to the identification of adequate research questions and the adoption of effective management options. While the state of knowledge regarding a few marine systems is reaching a sufficient state to identify some of the processes involved in particular geographic areas, it is unlikely that the specifics of these findings can be transferred to other areas even if the same or very similar ecosystems are involved. Management options are further frustrated by the wide range of agencies responsible for the observed impacts on a particular environment.

Figure 6.3: The main components of a study examining synergistic effects to illustrate some of the complexity of such studies. While an increase in all of these components (time, area, scale and scope) will theoretically improve the understanding of a particular situation the amount of effort required to achieve a result increases exponentially.



We have identified eight activities (agents), five mainly marine-based industries and three other land-based activities, largely responsible for the main threatening processes of significance in the marine environment, and thus having direct consequences for marine invertebrate conservation. These are:

  • Fisheries and other forms of biotic exploitation;

  • Aquaculture;

  • Shipping/transport;

  • Petroleum, gas or mineral exploration and production;

  • Recreational use and tourism;

  • Waste disposal;

  • Coastal development and modification;

  • Land use in catchments.

These industries and activities (summarised in Table 6.1) differ in the extent to which they affect marine habitats and invertebrates. It is also often difficult to differentiate and distinguish between the effects of particular threatening processes (Yen and Butcher 1997) because several may be involved.

6.10          Fisheries and other forms of biotic exploitation

“The uncertainty inherent in the scientific method has made scientific data extremely vulnerable in the face of the economic harm that has been predicted by the region’s commercial fishing industry in response to proposed govt regulation”. The image of the fisherman “as one of contemporary society’s last rugged individualists….. has resulted in the industry’s opinion…. being viewed as more credible than scientific data” (Brailovskaya 1998).

World fishery landings increased through the 1980s, but have now levelled at about 90 million tonnes per year, apparently the maximum sustainable yield. Thus, catches have not increased with population (and therefore demand), and prices have risen dramatically relative to other meat. Also, about 2/3 of the important commercially fished stocks are fully or over-exploited and many have been depleted, some to the point of economic extinction. Aquaculture now contributes more than 20% to global aquatic food production. World fishing fleets are still far too large, and many governments are (often covertly) subsidising them. The FOA calculates that US $124 billion is being spent per year to catch US $70 billion worth of fish (Tickell 1997).

Australia’s ocean waters are renowned for their low nutrient status. Although we have the third largest EEZ in the world, our total fisheries catch ranks about 50th. Australia lacks upwellings and discharges from large rivers resulting in a lack of nutrients to drive productivity. This, combined with poor results from exploratory fishing and research surveys, reinforces the pessimism about additional significant sustainable fisheries from the deep-sea (Newton 1999).

Earlier (Section 6.3), we dealt with over-exploitation of marine invertebrates as a threatening process. This section deals with all fisheries (finfish as well as invertebrates) and the various effects they can have, directly or indirectly, on populations, communities or ecosystems.

Issues with declining fisheries and impacts from fishing

6.10.1        Effects of fishing on non-target species, communities and ecosystems

Predators at the top of the food chain are particularly at risk of overexploitation (Section 6.3.1) but unexploited species also suffer from fishing activities - either directly (as bycatch) or indirectly through habitat damage (Section 6.10.2) or the removal of key species.

6.10.2        Commercial fisheries

While a wide range of methods are employed including trawls, dredges, pots and traps, purse seine nets, jigging, long lines etc. only some of these are used to directly harvest invertebrates. However, all these methods have some direct or indirect affects on invertebrate communities. In particular, trawling and scallop dredging have been identified as being of serious concern in recent literature (e.g., Dayton et al. 1995; GESAMP 1997; Hall 1999; see Section 6.10.2). Some illegal fishing methods used by some countries in the Indo-west Pacific region are seriously destructive, and include the use of explosives and cyanide on coral reefs (Barber and Pratt 1998; Jones and Hoegh-Guldberg 1999; Pet-Soede et al. 1999). Fortunately, as far as we are aware, these are not used in Australian waters. Other impacts from commercial fishing include rubbish dumping and other pollution such as oil spills. An overview of the ecological aspects of fisheries in temperate Australia is provided by Bell (1995).

Some methods of fishing have much greater impacts than others. A study in the UK showed that beam trawls and scallop dredges did much more damage than the lighter otter trawls and that areas closed to towed fishing methods were significantly different from those where these methods were used (Kaiser et al. 2000). Some indication of the impacts of each of the main fishing methods relevant to invertebrates, or their communities and habitats, is given in Table 6.4.  

6.10.3        Recreational and minor commercial or semi-commercial fishing

Recreational fishing is a very popular pastime in Australia, involving over 4.5 million Australians each year. Of these, 800 000 fish on 20 or more days per year and can be regarded as regular fishers (McNair 1992). While most of this activity is focused on finfish, molluscs, crustaceans and echinoderms also are directly targeted for food, and a range of invertebrates are used for bait. Activities such as bait collection have a minor commercial involvement.

While most forms of recreational fishing are unlikely to directly drive any targeted invertebrate species to extinction, they can remove considerable biomass, particularly from the accessible intertidal zone. This can lead to reductions in the density of harvested species, as well as effects on community structure (e.g., through removal of predators) and damage to habitats (e.g., through destructive collection techniques or access routes).

In the Cocos (Keeling) Islands, for instance, there is little commercial fishing but fish, clams, coconut crabs and mud crabs are heavily collected by local artisanal and recreational fishers and there are concerns that sites may be overfished (Caton et al. 1998; Fishery Status Reports for Commonwealth fisheries). Hand-collected giant clam (Tridacna gigas), coconut crab (Birgus latro) and mud crab (Scylla serrata) are very depleted locally. Other popular species, including rock lobsters (Panulirus spp.), spider shells (Lambis spp.) and clams are potentially vulnerable to overfishing; for instance, an estimated 50 000 to 70 000 spider shells are taken each year for food (Caton et al. 1998).

Methods employed by recreational fishers are outlined in Table 6.5 with an overview of the possible impacts that each method may have on invertebrate communities and habitats.

6.10.4  Management issues and recommendations

Management strategies applicable to coastal marine resources need to be at the level of ecosystems rather than species, should include regulations that accommodate biological and social realities, and adopt novel approaches such as the encouragement of co-management of resources (e.g., Griffiths and Branch 1997). In Australia, integrated management is rendered more difficult because management of the coastal zones is state-based and beyond three nautical miles is the responsibility of the Commonwealth. Thus, management strategies may differ considerably on either side of a state or territory border. In addition, such issues as indigenous access to marine resources are mostly still in the process of being resolved.

Many management regimes take into account recreational as well as commercial harvests, for example by incorporating size and bag limits for casual collectors. Hence, while the discussion below of management options is divided (as above) into sections for commercial versus recreational or semi-commercial fisheries, there is some overlap.

Recreational and minor commercial or semi-commercial fisheries

Intertidal collecting

Shell collecting / shell trade

Other exported invertebrates

6.11     Aquaculture

Marine aquaculture[135] (mariculture) involves the farming of seaweeds, shellfish, or fish. There are two major culture techniques; intensive and extensive. The term `intensive aquaculture' is generally used to describe projects where stock is confined (usually at high density) and artificially fed; this is the case for most fish farming. 'Extensive aquaculture' is the term used where stock is not closely confined and naturally available food is used; this describes most shellfish farming (NSW Fisheries 1998a). Aquaculture has been growing rapidly worldwide and in Australia (see Figure 6.4).

Figure 6.4: Global trends in aquaculture production, 1986 – 1995 (source: FAO Fisheries Department 1997)


6.11.1        Effects of aquaculture

Aquaculture has the potential to impact on the marine environment in a number of ways, depending largely on the species, culture method, stocking density, feed type, hydrography of the site and husbandry practices (Wu 1995). These impacts can include habitat damage during construction, and pollution, introduction of non-native species and diseases, consumption of natural resources and ecosystem changes during operation. The potential impacts of extensive aquaculture are quite limited given that food supplements are not used during the production process, though it is important to minimise any potential impacts which may occur during the construction or operation phase (NSW Fisheries 1998a; see below). The implications of aquaculture for biodiversity, particularly in relation to the threat posed by wetland destruction, use of chemotherapeutants and translocation of exotic plants and animals, are discussed by Beveridge et al. (1997).

6.11.2        Management issues and recommendations


Aquaculture, while reducing pressure on wild stocks in some cases, has environmental problems of its own. These include:

  • Destruction or alienation of habitat;

  • Pollution;

  • Introduction of pests - quarantine procedures - possible problems even within states let alone between states; and

  • Mixing of genetic stocks - genetics of existing populations of the species involved should be surveyed so that management options can be assessed based on actual data.

Management options

Buschmann et al. (1996) pointed out that regulations to protect the environment from the impacts of aquaculture, such as have been adopted in Chile in the last few years, can only be effective if other human activities, such as urban discharge, intensive agriculture fertilisation and pesticide utilisation, are taken into consideration, in an integrated perspective. Active research is currently being undertaken into new cultivation strategies, such as the use of integrated cultivation and the recycling of nutrient-rich waters, which should permit the diversification of this economic activity in Chile, while minimising the environmental impact. Wu (1995) discussed management options to ensure that aquaculture is sustainable, particularly in relation to pollution impacts. These included:

To these should be added:

6.12     Shipping and transport

As discussed in Section 6.5, shipping is the main vector for transport of exotic organisms from one region of the world to another. This industry is also responsible for a significant proportion of marine oil pollution, as well as some other forms of pollution including rubbish and waste disposal. Other impacts specific to the shipping and boating industry include physical damage (especially on coral reefs) due to anchoring and shipwrecks or groundings, and the toxic effects of anti-fouling paints, particularly TBT.

6.12.1        Shipwrecks and groundings

Shipwrecks and grounded vessels can cause local habitat damage but the main threat is usually from fuel or cargo spillage. The resulting contamination from such accidents can be broad scale, especially if a tanker (e.g., Torrey Canyon in the Scilly Isles, UK) or other type of bulk transporter is involved (see Section 6.6.1 for a specific discussion of the impact of oil and related products on marine invertebrates and communities).

On the ‘positive’ side, shipwrecks can form artificial reefs that add to the structural diversity of an area and provide good habitats for fish and invertebrates. In some areas, ships have been deliberately scuttled to provide such habitats.

Examples of groundings

6.12.2        Cruise ships

Cruise ships, as with other shipping, pose a serious threat to marine communities such as coral reefs and associated organisms. The effects of increasing numbers of cruise ships on corals, fisheries and tourism are discussed by Smith (1988). Qualitative and quantitative observations made under cruise ships anchored over disturbed and undisturbed sections of reef off Grand Cayman Island, West Indies showed 3150 m2 of previously intact reef destroyed by one cruise ship anchoring on one day (Smith 1988). From follow-up observations, and additional data from other cruise ship anchorings, recovery periods of more than fifty years were postulated (Smith 1988).

The number of large cruise ships and dive boats is increasing in Australian waters. In addition to the problems identified by Smith (1988), they may also introduce non-indigenous organisms via either hull fouling or ballast water. Currently only the GBRMPA controls the locations within the Park, where cruise ships may visit and anchor; regulations elsewhere are far less stringent.

6.12.3        Transport of exotics

See Section 6.5.

6.12.4        Antifouling paints

Biocidal antifouling paints are used on vessels to discourage or prevent the settlement and growth of fouling organisms (barnacles, algae, sponges, tubeworms, etc.). Fouling poses a significant problem for commercial and recreational shipping and boating, increasing drag, reducing the efficiency and manoeuvrability of affected ships, and increasing operational costs through higher fuel use and cleaning.

Over the years, a variety of active ingredients have been used in antifouling paints, including organomercury, arsenic and lead. Since the late 1960s, however, the mostly widely used antifouling additive has been tributyl tin (TBT), either in conjunction with other agents in copper-based paints or as the sole biocidal agent.

By far the mostly widely documented effect of TBT, however, is “imposex”, or pseudohermaphroditism, in which female gastropod molluscs develop male features. In advanced stages this can block the genital pore leading effectively to female sterility (Kohn et al. 1999).

6.12.5        Management issues and recommendations

Shipwrecks and groundings

Transport of exotics  

6.13     Petroleum, gas or mineral exploration and production

There are now many Acts, regulations, conventions and protocols associated with mining, including the Australian Environmental Protection Agency’s series on “best practice environmental management in mining”. Exploitation of the presumably vast mineral and oil resources on the ocean floor is in its infancy at present. Even so offshore petroleum is worth approximately $8 billion per annum and supplies 85% of Australia's petroleum needs and contributes $2.4 billion in tax revenue each year (Commonwealth of Australia 1998b). There is great potential for expansion of this industry in the future given dwindling land-based reserves and improving technology. Given our rudimentary state of knowledge about even the most fundamental issues regarding offshore ecosystems the potential for environmental damage is virtually impossible to estimate (e.g., Moore and Zeidner 1999). The ocean also has valuable mineral deposits, many of which occur in the deep ocean or on underwater volcanoes and ocean ridges, or on the sides of seamounts. These latter habitats are likely to harbour endemic taxa (see Section 5.3.1). Similarly, recent press reports regarding proposed mining operations on deep-sea "smokers" near New Ireland would be endangering a unique community of organisms restricted to this habitat.

The issues relating to oil (and other hydrocarbon) pollution are discussed in Section 6.6.1.

6.13.1        Oil and gas

Impacts associated with construction of drilling platforms and other infrastructure (damage to habitats and communities) and toxic and smothering effects of drilling fluids, wastes and leaked oil products have been long recognised (e.g., Davies et al. 1984). Lissner et al. (1991) point out the potential impacts on deep-water hard-substrate communities, primarily from anchor damage and sedimentation. Several studies have shown that drilling fluids have a detrimental impact on survival and recruitment of marine invertebrates, the effects mostly impacting benthic organisms as these wastes tend to settle rapidly (e.g., Anonymous 1995b; Raimondi et al. 1997; Cranford et al. 1999).

R. F. May (1992b) examined the issues resulting from petroleum exploration and development and oil spills on marine conservation reserves in Western Australia while Pendoley (1992) detected hydrocarbons in oysters and sediments in the remote Rowley Shelf.

6.13.2        Mineral exploration and mining

Marine mining for minerals is still in its infancy but is likely to increase in significance as terrestrial sources dwindle and technology improves.

6.13.3        Management recommendations

There are already tight controls regulating mining activities in Australia. However, environmental impact statements and environmental considerations prior to approval should:

  • Give greater attention to impacts on the benthic and pelagic invertebrate communities likely to be affected.

  • Mining exploration and operations should be done sympathetically, with impacts confined to as small an area as possible.

  • Dumping of spoil (from dredging for channel deepening etc. or from mining operations), will destroy any marine invertebrate communities in the area of dumping. Such activities should not be undertaken without an environmental impact assessment that takes account of the extent of the habitats being used for dumping, and the impacts on the fauna in those habitats.

  • Procedures should be put in place to minimise the impacts of drilling muds (e.g., Burke 1994).

6.14     Recreation and tourism

Over a quarter of Australians live within three kilometres of the sea and three quarters live within 50 kilometres of the coast (Zann 1995). Recreational activities that centre on the marine environment are an important pastime and part of our culture. Popular recreational activities include swimming, snorkelling and diving, sailing and related water sports (surfing, water skiing, windsurfing etc.), fishing and spear fishing, and a variety of intertidal activities such as tide pooling and shell collecting. Areas such as the GBR, Ningaloo Reef and Shark Bay in WA, Jervis Bay in NSW and the South Australian Bight, to name just a few areas, attract considerable numbers of tourists, both domestic and international, and are an important source of revenue.

Recreation and tourism are potentially among the most benign uses of the marine environment, and can in many respects be beneficial, serving to encourage an awareness of and enthusiasm for the marine environment, providing a forum for public environmental education, and supplying an economic motive (or even a means, in cases where user fees are levied) for its protection. Excessive or poorly managed use, however, can have significant impacts (e.g., Sala et al. 1996).

The economic and financial benefits of tourism are well known, and the impacts of visitors on protected areas has been widely recognised as an issue that requires careful management (e.g., Driml and Common 1995). Coral reefs are an especially popular attraction and considerable concern has been voiced over the potential impacts of excessive visitation (particularly from SCUBA diving impacts (Schleyer and Tomalin 2000) or general degradation resulting from tourism-associated development. For instance, Hawkins and Roberts (1997.) pointed out that the declaration of marine protected areas is often partly in response to their amenity value and increasing recreational use; yet their establishment often serves to attract further visitors, exacerbating the problem of over-use. For example, the Ras Mohammed Marine Park in Egypt received wide publicity in diving magazines and the National Geographic, so acting as a focus for the development of a thriving tourist industry based around scuba diving. At high intensities, however, this can cause damage, with recreational diving leading to wear and tear on reefs, pleasure boats increasing water pollution and anchor damage, and the hotels and other infrastructure harming the very resources tourists come to see (Hawkins and Roberts 1997). While coral reefs have received the most attention, many other types of habitats – particularly in the intertidal zone – also have the potential to be impacted by overuse or misuse (see State of the Environment Advisory Council 1996 for a series of case studies on the impact of tourism on the coastal environment).

The sections below deal with the impacts of various recreational and tourism activities on marine invertebrates and their habitats. The effect of recreational collecting of marine organisms is discussed in Section 6.10.3. Indirect effects of tourism, such as those resulting from increased development, damage during construction of tourist facilities, increased pollution loadings, etc., are dealt with in the sections on "Coastal development" (Section 6.16) and "Land use in catchments" (Section 6.17), below.

6.14.1        Management issues and recommendations

Increasing use of marine protected areas for pursuits such as recreational scuba diving may lead to biological damage and reduced amenity values in popular locations (e.g., Davis and Tisdell 1996). The relationships between biological and amenity values are discussed by Dixon et al. (1993) while Driml (1995) discussed the economic and financial values of the GBR. These authors argue that a blend of regulation and the use of economic instruments will provide better overall management of popular marine recreational sites than is presently the case. Education will also have a significant role to play by increasing environmental awareness and reducing the damaging impacts caused by users.

Limitations on the amount of anchoring, limits on access, requirements for visiting defined sensitive locations, limits on motorised water sports etc. tourism operator permits etc., are some of the ways in which recreational activities likely to damage sensitive sites can be controlled. However, there must also be an awareness of the need to allow users to obtain maximum benefits, as well as limiting their impact on other user groups. While there is a considerable current awareness of the need to limit damage in coral reef habitats, in determining areas at risk more attention needs to be paid to other habitats of significance to marine invertebrates.

Trampling in fragile habitats (particularly coral reefs, but also mangroves and saltmarshes) can be controlled by the designation of pathways or the construction of platforms for viewing, board walks etc., although even boardwalks have some effects (Kelaher et al. 1998a; Kelaher et al. 1998b). The construction of facilities designed to improve access and at the same time minimise impact is an effective management strategy - in that they can also achieve educational, "involvement" and "experience" goals. Devices such as boardwalks in mangroves and artificial pontoons on the reef achieve these goals and, if properly and sympathetically constructed and managed, have few significant impacts. There are, however, some impacts on benthic invertebrate communities in close proximity to the board walk, within distances of 3 m (Kelaher et al. 1998a; Kelaher et al. 1998b). Platforms on GBR reefs are permitted with stringent conditions, and monitoring must occur during the construction and operational phases. The GBR Authority has restricted the number to limit the impact on the “wilderness effect” for tourists, and regulation includes all rubbish and waste products being transported back to the mainland.

Specifically we recommend that:

  • More attention be paid to education and public awareness regarding the damage that can be done by diving and snorkelling on coral reefs and other habitats with fragile colonial organisms;

  • Trampling be minimised in sensitive habitats in popular areas by the construction of walkways, viewing platforms etc.;

  • That damage to habitats important to marine invertebrates be considered when restrictions to various boating activities (including water sports) are being formulated; and

  • Research be carried out on the impacts of various recreational activities on marine ecosystems so that this can be used as a basis for management.

6.15     Waste disposal

The sea is increasingly becoming a repository of waste. Its volume and physical properties result in enormous dilution effects and its chemistry and biology give it the capacity to recycle much of the deposited waste. In addition, the remoteness of the deep-sea makes this huge part of the ocean attractive for the disposal of waste that is unsuitable for disposal on land or coastal waters (Gage and Tyler 1991). But increasingly it is being shown that the oceans can disperse wastes and poisons, with, for example, DDT and other pollutants being recorded in Antarctic animals, plankton and seawater (e.g. Lukowski and Ligowski 1987; Joiris and Overloop 1991; Cripps 1992; Gupta et al. 1996; Inomata et al. 1996; Zimmermann 1997).

The oceans are treated as a “sink” for many of the wastes generated by society. These not only include sewage, but many industrial effluents and by-products, stormwater (carrying urban runoff and rubbish), and solid wastes, sewage sludge and, overseas, even include household garbage and radioactive wastes. In some cases these wastes are deliberately disposed of through ocean outfalls or by authorised dumping at sea; in other cases they are discharged into streams and rivers from which they are eventually carried to the sea. Even if sewage is treated, the sludge residues may contain elevated levels of toxic substances such as Cd, Cu, Pb, Hg, Zn or polychlorinated biphenols (Gage and Tyler 1991).

In the absence of any global policy to reduce the production of waste, the pressures on the terrestrial and inshore marine habitats are considerable and the use of the deep-sea as a repository for often dangerous waste is growing. Gage and Tyler (1991) discuss the problem of waste disposal in the deep-sea. They point out that on a larger scale (i.e. excluding shipwrecks etc) the proximal deep ocean is being used to dispose of dredge spoil, sewage sludge, pharmaceuticals and industrial wastes, and low level radioactive waste. The disposal of waste into the marine environment is controlled by the ‘Convention on the Prevention of Marine Pollution from Dumping of Wastes and other Matter’, better known as the ‘London Dumping Convention’, which has been in force since 1975 and provides a legal framework (involving 57 countries) to regulate dumping at sea. Although the deep-sea is considered remote from human activity, and therefore safe as a dumping ground, toxic effects such as decrease in oceanic productivity and biomagnification of toxic elements in the food chain could occur.

6.16     Coastal development

6.16.1        Impacts from coastal development

The impacts of coastal development are obvious and well documented (e.g., RAC 1993), these being responsible for the destruction or modification of coastal marine invertebrate habitats and communities, and its combined impacts are probably the most significant cause of the deterioration in coastal marine ecosystems. Almost 90% of Australia’s population lives in the coastal zone, about 90% of all building activity in Australia (1983-1991) took place there and it experienced very rapid rates of population growth (Burgman and Lindenmayer 1998), with the continuing development of a largely continuous, heavily urbanised ribbon along the coast from southern NSW to Central Queensland[141].

Coastal development can result in several threatening processes (e.g., habitat destruction (Section 6.4), pollution (Section 6.6), etc.). It includes urban and industrial development, and can involve activities that directly impact on marine environments such as land clearing, reclamation, beach constructions (e.g., seawalls, bridges and wharves), dredging estuarine waterways and sand dredging for construction or fill.

Examples of some of the impacts include:

  • The building of seawalls, groynes or other structures - these not only directly impact on littoral and supralittoral habitats but can result in the loss of beach, seagrass and mangrove habitats when current and wave patterns are altered.

  • Land clearing and/or loss of mangroves in estuaries leads to increased erosion resulting in increased sedimentation and smothering of benthic organisms, and turbidity (see also Section 6.6.1).

  • Increased nutrient run off and sewage disposal results in eutrophication (see Section 6.6.1).

  • Spoil from construction of roads etc. smothers habitats and results in increased turbidity (see Section 6.6.1).

  • Loss of coastal wetlands (e.g., for agriculture, particularly sugar cane) results in the loss of the beneficial filtering of the wetlands and leaching of acid sulphate soils (see Section 6.6.1).

  • The dumping of dredge spoil for land reclamation from busy harbours or offshore from industrial sites can be a problem when it is heavily contaminated with heavy metals and oil.

Studies by Glasby (1997), Glasby and Connell (1999; Glasby and Connell 2001) and Connell and Glasby (1999) have shown that artificial structures such as pontoons and marinas may increase the abundance and diversity of subtidal epibiota in the shallow areas of an estuary, they are not surrogate surfaces for epibiotic assemblages that occur on nearby natural rock. They suggest that urbanisation of estuarine habitats has consequences for the identity, diversity and abundance of subtidal epibiota. Glasby and Connell (1999) suggest that a great deal more research is needed to understand fully the consequences of adding new habitats to the marine environment.

6.16.2        Management issues and recommendations

It is vital that coastal planning instrumentalities consider the impacts of development proposals on all aspects of the marine environment (including marine invertebrate habitats and communities) and introduce regulations that minimise these. While developments in enclosed bays and estuaries are likely to cause the most damage, all developments leading to the loss of supralittoral, intertidal and shallow subtidal habitats must undergo assessments that include:

  • Their direct impact on marine invertebrates and their habitats;

  • An assessment of amount of similar habitat in the area; and

  • Whether any species in the estuary or bay affected are likely to be threatened within that area as a result of the development.

Given that there are relatively few marine ecologists or other marine biologists capable of undertaking such detailed assessments, this expertise should be developed at regional levels as a matter of urgency.

In order that such assessments can be better expedited, baseline inventories should be conducted on major bays and estuaries around the coast.

6.17     Land use in catchments

6.17.1        Impacts

The declining quality of terrestrial run off as a result of human modification of terrestrial systems (particularly through loss of native vegetation and overgrazing) can be one of the most significant anthropogenic threats in many coastal areas, including the GBR[142] region (Bennell 1979; Baldwin 1990; Bell 1991; Yellowlees 1991; Brodie 1995a; 1997), although there is debate about the severity of the problem (Brodie 1997; Section 6.6.1).

Moss et al. (1992) estimated that 15 million tonnes of sediment, 77 000 tonnes of nitrogen and 11 000 tonnes of phosphorus are discharged annually to the coastal waters of the GBR by mainland rivers. Overall, grazing lands contribute about 80 % of nutrients, sugarcane areas 15 %, and sewage approximately 1%. Most of the nutrients originate from erosion rather than from added fertilisers. Grazing lands can lose larger amounts of sediment than woodlands or forests  (1979). Much of the transportation of sediments occurs during flooding. On the GBR, Brodie (1997) points to a fourfold increase in sediment and nutrient transport in the last 40 years combined with a dramatic increase in fertiliser use. These trends probably are typical of Australia generally.

The estuarine parts of most river systems have been subjected to considerable pressures and changes. Recher et al. (1993) attempted to collect long-term data on the marine fauna of the Hawkesbury estuary, a river system that has been subjected to major changes including considerable development in some of the catchment. These authors determined that reduced freshwater runoff due to the construction of dams, enabled increased penetration of seawater upstream and, consequently, the upstream migration of marine taxa.

6.17.2  Management recommendations

We make the following recommendations concerning catchment management and how it relates to marine ecosystems and invertebrate communities. These largely follow standard recommendations for catchment management so are only briefly outlined.

  • More attention to be given to preventing habitat destruction and changes to catchments which then impact downstream in terms of changed hydrography and increased rates of run off

  • Reduction of terrestrial runoff by improved land management practices, reduction in clearing vegetation, restoration of vegetation, especially riparian strips;

  • Changes to agricultural practices including reduction in fertiliser and pesticide use and practices that reduce erosion;

  • Removal of nutrients and heavy metals from sewage discharge;

  • Educational programs leading to an increased awareness of the connections between land and the sea via rivers and coastal waters; and

  • Increased research into the effects of terrestrial inputs on marine ecosystems.

6.18     Summary of recommendations

Ensure that planning and management mechanisms are in place to reduce habitat alteration and destruction. All developments leading to the loss of supralittoral, intertidal and shallow subtidal habitats should be required to undergo assessments that include:

  • Their direct impact on marine invertebrates and their habitats;

  • An assessment of amount of similar habitat in the area; and

  • Whether any species in vicinity of the area affected are likely to be threatened within that area as a result of the development.

The detailed extent and condition of critical coastal habitats should be monitored on at least a statewide or, preferably, national level.

Encourage and facilitate experimental studies to assess likely impacts from habitat fragmentation, particularly on maintenance of taxon diversity and recruitment success.

Encourage and facilitate genetic studies on taxonomically and biologically different invertebrates to assess patterns and differences in the spatial extent of significant genetic structuring.

Continue with surveys for exotic invertebrates but broaden their scope and reassess the methodologies being used. Programs relating to the assessment of introductions should aim to:

  • Undertake baseline studies on native fauna;

  • Determine the effects of introduced taxa on native fauna and communities; and

  • Develop effective control strategies.

Improve the information and research base to assess and monitor the impacts of pollution on marine invertebrate communities. Information is required, in particular, on:

  • Long-term recovery;

  • Indicator species;

  • Biomarkers for marine communities (development of appropriate benchmarks for risk assessment; baseline monitoring criteria);

  • Development of effective management strategies to protect marine ecosystems; and

  • Experimental studies on the toxicity and sublethal effects on a range of invertebrates of a wide range of chemicals and other pollutants in marine ecosystems.

Gather and utilise invertebrate data in the Coastal Resource Atlas (CRA).

Development of policy to encourage and enable cooperation between different levels of government and government departments, including those responsible for land-based activities - particularly with regard to pollutants, sediments, development, resource utilisation, recreational activities etc.

Utilisation of international regulations, protocols and law where necessary to reduce the levels of relevant impacts (e.g., pollution and exotics from shipping, global warming, etc.).

Recognise that global warming and the resultant rise in sea levels and temperatures is one of the most serious threats facing coastal marine biodiversity.

  • Ensure the conservation of coastal biodiversity global warming must be slowed as much as possible.

  • Facilitate and conduct research into the likely impacts of rising sea levels and atmospheric and oceanic warming to enable forward planning to alleviate impacts.

  • Establish coastal zone policies that allow adaptive responses to rising seas by making way for the shoreward movement of coastal ecosystems as sea level changes.

Continue and enhance research into the causes of population outbreaks of destructive or harmful marine species.

  • Studies on the basic biology, ecology and distribution of at least keystone taxa would greatly improve the knowledge base so that basic information was available when required.

  • Improve the knowledge base regarding diseases of marine invertebrates.

  • Address issues regarding the spread of diseases by translocation of aquaculture stock and the introduction of exotic species (either as pests or for aquaculture).

  • Guidelines on reporting diseases and suitable responses should be established for significant events.

Recognise that synergistic effects are important and that their recognition is critical to the identification of adequate research questions and the adoption of effective management options.

Management strategies applicable to coastal marine resources need to be at the level of ecosystems

Address unresolved issues relating to indigenous access to marine resources.

There is a need for better data so that the degree of threat posed from harvesting for most marine invertebrates can be more accurately established. This should include:

  • Accurate catch data (both professional and amateur);

  • Knowledge of species biology, population genetics, structure and size;

  • Historical data;

  • Suitable reference areas for comparison of exploited with unexploited populations; and

  • Certainty of taxonomic status.  

Fisheries (whether commercial or recreational), if they are to be sustainable, should at least  address the following:

  • Manage breeding stocks of the target species;

  • Minimise effects on non-target species (minimisation of bycatch); and

  • Minimise impacts on habitats.

Develop marine refugia as a management strategy for sustainable fisheries, including coastal, shelf and slope trawl fisheries.

  • Marine reserves should be established on the principle of ‘no-take’, and these areas should be, where possible, large areas.

  • Marine reserves must not, however, replace conventional management options but rather complement them.

  • Ban scallop dredging from all but a few strictly controlled areas (especially as scallop aquaculture is now viable).

Require Environmental Impact Statements (EIS) for any new commercial fishing operations.

Manage intertidal collecting and the conservation of intertidal assemblages on rocky shores by:

  • Use of general or selective bag limits, or size limits;

  • Bans on harvesting in selected areas;

  • Improve public education – including signs at closed areas, advertising, agreed penalties etc.; and

  • Evaluate effectiveness.

Ensure that aquaculture developments have management that minimises:

  • Destruction or alienation of habitat;

  • Pollution;

  • The introduction or translocation of pests; and

  • Mixing of genetic stocks.

Encourage and enforce relevant regulations relating to shipping (both private and commercial)  such as:

  • Those that encourage safety and will reduce impacts from shipping accidents (such as oil spills);

  • Discharge of ballast water in oceanic water;

  • Hull cleaning should be carried out in such a way that will prevent any exotic organisms being able to survive; and

  • Use of the least toxic and damaging antifouling measures.

Encourage and facilitate research on environmentally friendly anti-fouling measures.

Exploration and development of new mining and oil and gas resources activities should give greater attention to impacts on the benthic and pelagic invertebrate communities likely to be affected.

Management of coastal resources should ensure that impacts from visitors and recreational activities (including boating) are properly managed to cause as little harm as possible to marine and supralittoral environments.

  • More attention be paid to education and public awareness regarding the damage that can be done by various activities; and

  • Research should be carried out on the impacts of various recreational activities on marine ecosystems so that this can be used as a basis for management.

Develop expertise in marine biological assessment at regional levels as a matter of urgency.

  • To expedite assessments baseline surveys should be conducted in key locations around the coast.

With regard to catchment management and how it relates to marine ecosystems and invertebrate communities, we recommend that:

  • Attention to be given to downstream impacts by reduction of terrestrial runoff, improved land management practices and reduction in pollutants such as sewage and fertilisers;

  • Educational programs be encouraged and developed to increase awareness of the connections between land systems and the sea; and

  • Research into the effects of terrestrial inputs on marine ecosystems be encouraged and facilitated.


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