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Riverine aquatic protected areas: protecting species, communities or ecosystem processes?

John Koehn

Cooperative Research Centre for Freshwater Ecology
Arthur Rylah Institute for Environmental Research
123 Brown St.
Heidelberg 3084
Australia

Freshwater ecosystems are subject to a greater range and intensity of direct and indirect pressures than many other ecosystems. Rivers are linear with no immediate upstream or downstream boundaries, long ‘edge effects’ and many aspects of their functioning are dependent on catchment and land management issues occurring outside the immediate riverine area. Australia has a low diversity of freshwater fish species, so protection is of high importance for this component of biodiversity. The objectives for riverine aquatic protected areas should be to protect species, ecological communities and ecological processes. How well protected areas realistically meet these objectives is the key question. This issue is discussed using a 200km reach of the Murray River from Yarrawonga to Barmah as an example. This river reach contains a critically endangered species, the Trout cod, a listed aquatic community and is influenced by a range of altered ecological processes and threats including barriers to fish passage, altered water flows, angling and habitat degradation. It would appear that riverine aquatic protected areas may be able to provide some protection for some species and some of their habitats, but additional management actions may need to be undertaken outside of the protected area to address some threats, especially those affecting wider ecosystem processes.

Introduction

Protected Areas are seen as an integral part of conservation management although their roles are often not explicitly defined. Terrestrial reserves have an extensive theoretical basis for their design and include concepts form island biogeography, patch dynamics and genetics (Meffe and Carol 1994). Such a framework is still in its infancy for marine reserves (Allison et al. 1998) and designs drawn from experiences in the terrestrial realm may not be valid due to differences in scale and variability (Steele 1985). Riverine Aquatic Protected Areas (APAs) are, however, a new concept with little available theoretical basis for their design.

In south-eastern Australia, the objectives of key biodiversity and river restoration strategies include the protection of species, ecological communities and ecological processes (Natural Resources and Environment 1997; Murray-Darling Basin Commission 2002). APAs are one of the actions identified to achieve these objectives (Murray-Darling Basin Commission 2002). This paper explores the realistic levels of protection that could be afforded these different ecological units within a riverine APA, using an example reach on the Murray River in south-eastern Australia.

Riverine ecosystems

The nature of freshwater ecosystems means that they are subject to a greater range and intensity of direct and indirect pressures than many other ecosystems. Rivers are linear systems with no immediate upstream or downstream boundaries, have long ‘edge effects’ and many aspects of their functioning dependent on catchment and land management issues occurring outside the immediate riverine area. The linear nature of any riverine reserve leaves them susceptible to the impacts of actions that may occur upstream, downstream or in their catchment often outside any protected zone. Rivers can flow across different management zones and State jurisdictions, often leading to less than uniform management objectives.

The Murray River

The Murray River is one of the world’s longest rivers, flowing over 2500 km from source to the sea. It is heavily regulated with two major water storages (Hume Dam and Dartmouth Dam) in its upper reaches. The main channel forms a major conduit for the delivery of irrigation water to downstream reaches. The Murray-Darling Basin Commission through a range of multi State agreements that include water provisions for South Australia controls water within the river. Regulation means that there have been many changes to the flow regimes including reductions in overall river mouth outflows, reductions in flooding and seasonal flow reversals (Close 1990). The Murray River forms the State boundary between New South Wales and Victoria, with jurisdiction over the river being controlled by NSW.

Aquatic species

Most attention to date has focussed on the larger aquatic species, mainly fish, despite the fact that more than 439 different types (or taxa) of aquatic macroinvertebrates have been collected from the Murray River (Bennison and Suter 1990). The number of fish species in the Murray River is relatively low by world standards, containing only about 30 native species, several of which are restricted to the lower river zones and associated with marine or estuarine reaches (Koehn 2002). Several groups are undergoing taxonomic revisions that could result in the description of new species. Whilst this number of species may be expected of a river with a relatively low overall discharge, it is dramatically lower than the 1300 fish species described for the Amazon Basin (Cadwallader and Lawrence 1990). Eight introduced fish species are also present in the Murray River. Whilst floodplain and aquatic plants are recognised as a key component of the rivrine ecosystem they are not dealt with in this paper.

Most native fish species in the Murray River have however, suffered major declines over the past fifty years (eg. Cadwallader 1978; Cadwallader 1981; Cadwallader and Gooley 1984; Harris and Gehrke 1997). The causes of such declines include changes to flows, habitat alterations, interactions with exotic species, cold water pollution, barriers to movement and overfishing (Cadwallader 1978, Koehn and O’Connor 1990a, Kearney et al. 1999). There is concern about the long-term future of many species, with seven fish species being considered nationally threatened (Koehn 2002). This includes the critically endangered Trout Cod Maccullochella macquariensis (Australian Society for Fish Biology 2001), whose natural range is now restricted to the river reach considered in this paper. Of particular community concern is the decline of many ‘flagship’ species such as Murray cod Maccullochella peelii peelii, Trout cod, Silver Perch Bidyanus bidyanus and Catfish Tandanus tandanus. Commercial fisheries for species such as these have all been greatly reduced or ceased (Reid et al. 1997). Recreational angling remains popular for native species such as Murray Cod and Golden Perch although the capture of Trout Cod and Silver Perch is now prohibited. Whilst most native species have declined, small areas such as Lake Mulwala still provide anglers with productive native fish fisheries.

The study reach

The 200km reach of the Murray River from Yarrawonga to Barmah (Figure 1) provides a useful example to illustrate the practicalities of what could be achieved in a riverine protected area. This river reach has already been suggested for consideration as a Freshwater Aquatic Reserve (Hankinson and Blanch 2002) and has natural assets including:

• The only natural remaining population of the critically endangered Trout cod;
• Representation of a listed aquatic community (Table 2);
• Excellent instream habitat;
• Good native fish populations, especially compared to upstream and downstream reaches;
• Largely intact riparian zones and floodplains;
• The Barmah- Millewa forests.
• Culturally significant areas

There is also substantial data for this reach as a scientific study site (Koehn and Nicol 1998; Koehn et al., 1999; Nicol et al., 2000), and baseline ecological data could be used as a reference for rehabilitation of other river reaches. Eg. demonstration reaches (Murray-Darling Basin Commission 2002; Barrett and Ansell in press).

Nineteen species of native fish currently reside in the study reach (Table 1) and are an important component of the biodiversity, ecology and culture of the Murray River. A key feature of the study reach is Lake Mulwala which is used to feed irrigation water from the river to the Mulwala and Yarrawonga irrigation channels (Jacobs 1990). These channels can take up to 50% of the river inflows during an average irrigation season (C. Fitzpatrick, pers. comm.).

Major inflowing tributaries include the Ovens (largely unregulated) and Goulburn (largely regulated) rivers, with the Edwards River being the major outflowing tributary (Figure 1). In order to address the issues and influences on the study reach consideration is given to four zones:

Zone 1:	Yarrawonga to Barmah
Zone 2U:	upstream - Yarrawonga to Lake Hume
Zone 2D:	downstream - Barmah to Torrumbarry
Zone 3:	Whole of river - upstream of Lake Hume; downstream of Torrumbarry

Figure 1 near here

Managing ecological units

Protected areas may be established for their habitats, ‘naturalness’, scientific or recreational value, biodiversity/conservation, profile, etc. Marine reserves protect critical areas, provide refuge for intensely exploited species and act as buffers against management miscalculations (Allison et al. 1998). Hankinson and Blanch (2002) have suggested the establishment of different classifications of freshwater reserves with different levels of protection. Whatever the level of protection, or the objective of the APA, to achieve the best ecological outcome we need to consider the level of ecological unit that we are trying to protect. Ecological units range from individuals, to populations, to communities, to ecosystems. Each of these ecological units has linkages to other ecological units and associated with it are a range of habitats and processes that are integral to its well being (Table 3).

Table 3: Ecological unit definitions and process requirements.

Ecological unit (Boulton and Brock 1999)	Definitions (Lampert and Sommer 1997)	Ecosystem Processes (Boulton and Brock 1999; Lampert and Sommer 1997)
Species
Individual	Single organism	Metabolic rates, reproduction, movement.
Population	A group of individuals of the same species that occupies a particular location at a given time.	Population growth, recruitment, recolonisation, competition.
Community	The sum of all the interacting populations in the habitat.	Interactions (competition, predation, symbiosis).
Ecosystem	The comprehensive unit of communities and their interactions with the abiotic environment.
Biotic	From living organisms	Energy production and transfer, trophic levels/food chains, nutrient cycling, biodiversity, biogeographic patterns, evolution, succession, habitat inputs.
Abiotic	From non-living factors	Hydrology, flows, wind, light, temperature, chemical and physical processes and cycling (eg. oxygen, pH, N, erosion, sedimentation).

Conservation management has moved largely from a species by species approach (managing individuals and species) to one in favour of communities and ecosystem protection. Preservation of ecosystems “protects more human values, serves wider human goals and ultimately, saves more species than do expensive efforts to save species” (Norton 1986). In order to achieve this there needs to be an understanding of the associated ecological processes.

Protecting species

Protection of individual species has usually been the first step in most legislative protection. The Murray River’s low diversity of freshwater fish species heightens the importance of protection for the species level component of biodiversity. Species are conserved because they are rare, threatened, endemic, large, attractive or of recreational or economic importance. Some species should however be conserved because they have a disproportionate effect on the persistence of all other species – ‘keystone’ species (Bond 1994). Whilst this term was first used to describe marine predators, such species are those ‘whose activity and abundance determined the integrity of the community and its unaltered persistence through time, that is stability (Paine 1966, 1969). Whilst the interactions of such species may be complex, subtle or difficult to define, this approach perhaps belies the need to look beyond the protection of single species towards their interactions with other species and the ecosystem. Ehrlich and Ehrlich’s (1981) ‘rivet hypotheses’ in which they likened species to the rivets on an aircraft – if you lose enough then you crash – did not specify whether or not the rivets all had the same structural importance. It is unlikely that all species have equal function and it is the ecological functioning that we should concentrate on protecting. ‘Keystone’ species in this reach may be Murray cod, as a top level predator, or perhaps the freshwater shrimp Paratya australiensis, an abundant macroinvertebrate.

Whilst ‘keystone’ species have not been determined for the Murray River, there may be other ways in which the protection of individual species can be of importance. Murray cod is likely to be a ‘focal species’ (Lambeck 1997) which can be used to represent the needs of several other species that may be susceptible to similar threatening processes (eg. Trout cod or Golden perch Macquaria ambigua). The public identification with such a ‘flagship’ species would assist with such protection.

A fundamental assumption of protected areas is that they will protect populations within their boundaries. But what if the species moves outside these boundaries, even if only for a component of their life cycle? The nature of many fish species means that components of their life cycles (eggs, larvae, juveniles or adults) may not remain within the limits of a riverine protected zone.

Patterns of population replenishment for fish species fall into four categories (Carr and Reed 1993):

Short dispersal species which have population which can be considered self- replenishing at the reserve scale

Limited distance dispersers, which may disperse beyond the reserve boundaries, but into areas mostly adjacent the reserve,

Longer dispersals – which may have only one or a few actively recruiting populations and rely on the source population for replenishment

There may be several populations that all supply recruits to a common larval pool.

Species in the study reach can be largely categorised into A, B or C (Table 4).

Table 4: Movement patterns of fish species in the study reach (from Cadwallader and Backhouse 1984; Koehn and O’Connor 1990b).

A - within Zone 1	B - into adjacent Zones 2U and 2D	C - whole of river
River Blackfish	Broad-finned Galaxias	Short headed lamprey
Flat-headed Galaxias	Murray Cod	Golden Perch
Mountain Galaxias		Silver Perch
Trout Cod		Bony Herring
Southern Pygmy Perch
Freshwater Catfish
Carp Gudgeons
Flat-head Gudgeon
Dwarf Flat-head Gudgeon
Australian Smelt
Murray Hardyhead
Non-specked Hardyhead
Crimson Spotted Rainbowfish

About 30% of the fish species present will not reside permanently within Zone 1. Therefore these species cannot be protected within this APA alone. The movment requirements of most of these species are however unknown (Koehn and O’Connor 1990b). In addition, many of the other species exhibit larval drift (Koehn and Nicol 1998; Humphries and Lake 2000), which is largely unquantified in terms of percentage of larval population involved or the distances travelled downstream. This means that the limited movements (A) categorised for several species may really only apply to their adults. Mallen-Cooper et al. (1995) found large numbers of juvenile Silver Perch moving upstream through a fishway, presumably to recolonise. The short-headed lamprey Mordacia mordax has a marine phase to its lifecycle. In such cases, consideration may need to be given to separate APAs to protect different life stages. Most of the aquatic invertebrates are relatively sedentary and are likely to be able to be protected within the APA (Suter and Hawking in press; P. Suter pers. comm.).

Threatened species (see Table 1) rarely occur just in one zone. Although Zone 1 contains the only remaining natural population of Trout cod, many actions have been suggested and implemented in an attempt to recover this species (Brown et al., 1998). These include the protection of another translocated population and attempts to establish further populations through restocking. There is the potential for the expansion of the Murray River Trout cod population to expand outside zone 1 both upstream and downstream. The protection of Trout cod in an APA would assist this expansion and may provide greater numbers of individuals to assist in the establishment of new populations than already occurs. Whilst the taking of Trout cod by anglers is prohibited, mortalities may occur though accidental capture and it has been recognised that this population is sensitive to any increases in mortalities (Todd et al., in press).

Furthermore, the objectives of protected areas should not only be to protect species but also adequate amounts of the habitats that they use. This should include protection of areas such as the adjoining floodplain. Although to date there is little evidence for use of the floodplain by fish (Humphries et al., 1999), it may be important for a range of processes such as the supply of nutrients.

Protecting ecological communities

There is an increasing view that ecological communities should receive more attention for protection rather than individual species. If the goal of the protected area is to protect a broad range of species, then the range of complex interactions between these species (competition, predation, and symbiosis) needs to be taken into account and the priority should be to protect the community rather than single species. Ecological communities are also considered under threatened species legislation with the ‘Lowland Riverine Fish Community of the Southern Murray-Darling Basin’ listed under the Flora and Fauna Guarantee Act in Victoria and ‘The aquatic ecological community of the Lower Murray, Murrumbidgee, and Tumut Rivers’ (New South Wales Fisheries 2002) listed under the Threatened Species Schedules of the Fisheries Management Act in New South Wales (Table 3). This latter community is also under consideration for listing under the Federal Environment Protection and Biodiversity Conservation Act.

It is clear that not all components of the ecological community remain within Zone 1 (Table 4). Thus, whilst most members of the aquatic community would be protected by an APA at the scale of Zone 1, others such as the mobile fish species would not. The roles of particular functional groups (eg. top level predators) in maintaining ecosystems are important, but rarely considered when protecting individual species but may be overcome by protecting communities and their interactions. Protection of aquatic communities such as those listed cannot be undertaken without consideration of the threats that are imposed upon them (see below). These threats are considered in a draft recovery plan for Lowland Riverine Fish Community of the Southern Murray-Darling Basin (Brown et al, in press) and the ‘Draft Native Fish Strategy for the Murray-Darling Basin’ (Murray-Darling Basin Commission 2002). These plans address a wider range of issues, threats and actions across the Basin including consideration to socio-political issues.

APAs can protect some components of aquatic communities. In the example river reach about 50% of adult fish species may be protected, but some larvae and juveniles may not be. Protection levels for the aquatic invertebrate community will be much higher.

Protecting the ecosystem and biological processes

The concept of ecosystem management is based on the simple fact that the survival of species is inherently intertwined with the survival of many other species in the same ecosystem. Whilst conserving species and biodiversity will happen only through the conservation of habitats and ecological communities in which the species live (Miller 1996) it is also necessary to ensure that the processes which ensure the functioning of the ecosystem are maintained.

Properties of ecosystems and ecosystem processes are a function of abiotic factors and biotic ecosystem components. The complexities of such interactions usually mean however that the understanding of ecosystem processes and their influences on management are less than that of individual species. Ecosystem processes include both static and dynamic interaction and include primary production and consumption, secondary production, energy and nutrient flow, biogeochemical cycles, succession and processes that structure communities. These processes and those relating to species and community functioning (Table 1) underpin the ecosystem and its biodiversity. In particular they support ecosystem resilience, which is the ability of the system to recover after disturbance (Schlapper and Schmid 1999). This functional approach to biological conservation assures the resilience of ecosystems (Folke et al. 1996). For ecosystem function to be maintained a minimum composition of organisms is required to develop trophic relationships to mediate energy flow and the cycling of elements (Folke et al. 1996), but this must be accompanied by the maintenance of physical processes such as provision of light or flows .

Whilst ecosystems and ecosystem processes are not specifically protected by legislation, the listing of Potentially Threatening Processes under threatened species legislation is intended to address some threats which are largely alterations to ecosystem processes.

List of Potentially Threatening Processes under the Flora and Fauna Guarantee Act in Victoria include:

• Alteration to the natural flow regimes of rivers and streams.
• Alteration to the natural temperature regimes of rivers and streams.
• Degradation of native riparian vegetation along Victorian rivers and streams*.
• Increase in sediment input into Victorian rivers and streams due to human activities.
• Input of toxic substances into Victorian rivers and streams.
• Introduction of live fish into waters outside their natural range within a Victorian river catchment after 1770*.
• Prevention of passage of aquatic biota as a result of the presence of instream structures.
• Removal of wood debris from Victorian streams*.

* Similar processes are listed under the Fisheries Management Act 1994 in New South Wales

Recent scientific assessments of flow and environmental impacts along the Murray River (Thoms et al. 2000; Jensen et al. 2000) highlight how threats change through the river reaches. Most of the threatening processes identified for the river zones considered in this study (Table 4) have more direct impacts at the ecological process level than for the community and species. Few of the solutions available are from actions that may be undertaken within Zone 1. Hence to protect ecological processes within the APA, actions outside of the APA need to be undertaken. Processes that are protected at the APA scales (eg. recruitment of some species) not only benefit the APA but also the adjoining reaches.

Table 4 near here

Focal species such as Murray cod may be used to highlight the importance of addressing threats. The protection and use of an individual species can therefore assist in the protection of community and ecosystem processes if the threats are clearly identified. Some threats, however, have outcomes that are not so obvious. For example, if turbidity is increased, then productivity is reduced and sight-feeding fish are disadvantaged. The impacts of threats such as cold water pollution, which reduces the spawning success of many species in Zone 2U (Koehn 2001), but has largely dissipated when water reaches Zone 1, may still affect the population and community of Zone 1 through reduced recruitment from upstream.

Solutions that can realistically be achieved by management actions undertaken at the APA scale include habitat protection (snags, riparian zones and floodplains) and restrictions on fishing. Cold water pollution (which affects zone 2U) could be addressed by remedial actions undertaken at Lake Hume. Exotic species need to be addressed at a wider scale (Carp Control Coordinating Group 2000) although actions in some specific areas (such as Barmah for carp Cyprinus carpio (Stuart et al., 2001) may have greater impacts. Restrictions to fish passage due to barriers can be addressed at a local level although the benefits are likely to apply beyond the immediate reach. For example, the fishway at the Torrumbarry weir (Zone2D) allows fish upstream into Zone2. The operation of the fish lift installed at Lake Mulwala will allow fish to move out of Zone 1 into Zone 2. Lake Hume remains a barrier at the upper reach of Zone 2U. Most issues relating to river flows need to be addressed at a scale beyond that of an APA.

Managing ecosystem processes also requires an understanding of the concept that ecological change can be episodic rather than gradual. Ecosystem change happens at a range of scales and ecosystems do not necessarily have a single equilibrium, so are moving targets for management. Therefore management needs to be adaptable. Episodic events such as floods may be important for the resetting of system processes, but many of these mechanisms are not well understood. An APA may provide an ideal location to investigate the influence of various management regimes on ecosystem function.

Measuring the effects of the protected area

Depending on the limitations of activities within the protected area, some additional pressures may be placed on the environments outside the protected area. For example, if angling were to be banned, then some of the existing angling pressure may transfer to adjacent areas that may not be able to cope. Similarly, actions taken within the APA may affect adjacent zones. For example, what will be the effect of the provision of upstream fish passage via the fish lift at Lake Mulwala on the existing fish populations downstream? The success of any APA needs to be monitored both within and outside the area that actions are applied to. APAs may therefore provide opportunities to investigate the effects of management changes eg. The implementation of a fishing ban on populations.

Conclusion

Riverine APAs are an essential component of conservation as they can provide protection of unique critical areas, habitats and for some localised species. In this example reach they provide protection for most invertebrate species and up to 70% of fish species present. They provide insufficient protection alone however for mobile species and for threats that can impact on them from outside their boundaries. As APAs are not isolated from, but can be impacted by external threats, these threats also need to be addressed to protect wide ranging species and so that the effectiveness of the APA itself is not compromised. Ecosystem processes cannot be managed at the APA scale but in addition to the measures undertaken within the APA, must be addressed at the larger scale to ensure that the APA is protected. APAs will not be effective for threats such as water quality issues, changes in climate, invasion by exotic species or spread of diseases. Many of the actions that are required for APAs should be considered for the whole river system to ensure the restoration of native fish populations (Murray-Darling Basin Commission 2002). The use of ‘flagship’ species to promote APAs and their protection may be useful as ‘Protecting fishes will help to protect aquatic biodiversity, ecosystems and invertebrates (Moyle 1995).’

Key words

Freshwater, Murray River, aquatic protected areas, communities, ecosystem

Acknowledgments

Thanks to Simon Nicol and Sabine Schreiber for their comments on this manuscript, to Phil Suter for discussion on macroinvertebrates, Tarmo Raadik for assistance with the taxonomic species list and to all those who have worked with me on the Murray River.

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Figure caption:

Figure 1. Site map of the study reach under consideration for an Aquatic Protected Area and adjoining reaches of the Murray River.

Table 1: Species list and conservation status for freshwater fish of the Murray River (Yarawonga to Barmah) (modified from Koehn 2002). * = past distribution only, EPBC = Environment Protection and Biodiversity Conservation Act 1999, Protection Act, ASFB= Australian Society for Fish Biology 2001 listing; CE= critically endangered; E=endangered; V=Vulnerable; Epop = endangered population in New South Wales; FFG = listed under the Flora and Fauna Guarantee Act, Victoria. P = New South Wales Protected species (ie no take). (P) = Protected from commercial take, UC = under consideration. Note that broad-finned galaxias is a coastal nativ especies introduced itno the upper Murray River (Waters et al. 20002).

		Listing
Common name	Scientific name	National		Vic	NSW
Native freshwater species		EPBC	ASFB
Short-headed lamprey	Mordacia mordax
River Blackfish	(a) Gadopsis marmoratus			DD
Broad-finned Galaxias	Galaxias brevipinnis
Flat-headed Galaxias	Galaxias rostratus		V	DD
Mountain Galaxias	Galaxias olidus			DD
Murray Cod	Maccullochella peelii peelii	UC		V, FFG
Trout Cod	Maccullochella macquariensis	E	CE	CE, FFG	E,P
Golden Perch	Macquaria ambigua			V
Macquarie Perch*	Macquaria australasica	E	E	E, FFG	V,P
Silver Perch	Bidyanus bidyanus		V	CE, FFG	V,P
Southern Pygmy Perch	Nannoperca australis				V
Australian Smelt	Retropinna semoni
Freshwater Catfish	Tandanus tandanus		V	V, FFG	(P)
Bony Herring	Nematalosa erebi
Southern Purple Spotted Gudgeon*	Mogurnda adspersa		E	CE, FFG	Epop
Carp Gudgeons (species complex)	Hypseleotris spp
Flat-head Gudgeon	Philypnodon grandiceps
Dwarf Flat-head Gudgeon	Philypnodon sp.			FFG
Crimson Spotted Rainbowfish	Melanotaenia fluviatilis			DD, FFG
Murray Hardyhead	Craterocephalus fluviatilis
Non-specked Hardyhead	Craterocephalus stercusmuscarum fulvus	V		E, FFG	E
Introduced species
Brown Trout	Salmo trutta
Rainbow Trout	Oncorhynchus mykiss
Carp	Cyprinus carpio
Tench	Tinca tinca
Goldfish	Carassius auratus
Redfin (English perch)	Perca fluviatilis
Gambusia	Gambusia holbrooki
Weatherloach	Misgurnus anguillicaudatus

Table 2: Species list for the aquatic ecological community in the natural drainage of the lower Murray River catchment.

Fish
Mordacia mordax (Short-headed lamprey)	#Nematalosa erebi (Bony bream)
Galaxias olidus (Mountain galaxias)	#Galaxias rostratus (Murray jollytail)
Retropinna semoni (Southern smelt)	#Tandanus tandanus (Freshwater catfish)
*#Craterocephalus fluviatilis (Murray hardyhead)	#Craterocephalus stercusmuscarum fulvus (Non-specked hardyhead)
#Melanotaenia fluviatilis (Crimson-spotted rainbowfish)	*#Ambassis agassizi (Olive perchlet)
*#Maccullochella macquariensis (Trout cod)	#Maccullochella peeli peeli (Murray cod)
#Macquaria ambigua (Golden perch)	*#Macquaria australasica (Macquarie perch)
*Nannoperca australis (Southern pygmy perch)	Gadopsis marmoratus (River blackfish)
*#Bidyanus bidyanus (Silver perch)	#Hypseleotris klunzingeri (Western carp gudgeon)
Hypseleotris sp. 4 (Midgleys carp gudgeon)	Hypseleotris sp. 5 (Lake’s carp gudgeon)
*#Mogurnda adspersa (Purple-spotted gudgeon)	#Philypnodon grandiceps (Flat-head gudgeon)
Philypnodon sp. (Dwarf flat-head gudgeon)
Crustaceans
Austrochiltonia australis (water scud)	Paratya australiensis (freshwater shrimp)
Austrochiltonia subtennuis (water scud)	Macrobrachium australiense (freshwater prawn)
Bosmina meridonalis (water flea)	Cherax destructor (Yabbie)
Daphnia lumholtzi (water flea)	Euastacus armatus (Murray cray)
Boeckella fluvialis (copepod)	Tachea picta (shrimp lice)
Caridina mccullochi (fresh water shrimp)	Heterias pusilla (freshwater slater)
Insects
Antiporus femoralis (water beetle)	Micronecta gracilis (Water bug)
Antiporus gilberti (water beetle)	Microvelia paramoena (water bug)
Chironomus cloacalis (midge)	Xanthagrion erythroneurum (dragonfly)
Coelopynia pruinosa (midge)	Hemicordulia tau (dragonfly)
Cryptochironomus grisiedorsum (midge)	Austrogompus cornutus (dragonfly)
Kiefferulus martini (midge)	Notostricta solida (dragon fly)
Procladius paludicola (midge)	Anisocentropus latifascia (caddis fly)
Tanytarsus fuscithorax (midge)	Ecnomus pansus (caddis fly)
Micronecta annae annae (water bug)	Hellyethira eskensis (caddis fly)
Molluscs
Alathyria condola (bivalve)	Austropeplea lessoni (snail)
Alathyria jacksoni (bivalve)	Glyptophysa gibbosa (snail)
Corbiculina australis (bivalve)	*Notopala sublineata hanleyi (snail)
Sphaerium problematicum (bivalve)	Thiara balonnensis (snail)
Sphaerium tasmanicum (bivalve)	Velesunio ambiguus (bivalve)
Other
Ephydatia ramsayi (freshwater sponge)	Brachionus falcatus (rotifer)
Eunapius fragilis (freshwater sponge)	Brachionus novaezealandia (rotifer)
Heterorotula contraversa (sponge)	Microscolex dubius (oligochaete worm)
	Temnocephala chaeropsis (flatworm)

* = proposed or listed threatened species under the Threatened Species Schedules of the Fishereis Management Act 1994.
# = fish species included in the Flora and Fauna Guarantee Act listing for the Lowland riverine fish community fo the southern Murray-Darling Basin (this listing also included Macquaria australsica, Macquarie perch).
The total species list of the community is much larger than that given above. Only fishes, most macro-molluscs and most macrocrustaceans have been listed comprehensively (New South Wales Fisheries 2002).

Table 4: Key threatening processes for the river zones under consideration in this study. * = present in that zone.

Key threatening processes	Zone 1	Zone 2U	Zone 2D	species	community	Ecosystem process	Affect adjoining zones?	Solution in Zone 1?
Constant flows	*	*	*			Yes	Yes	Partly
Unseasonal high flows	*	*	*			Yes	Yes	No
Reduction in flooding	*	*	*			Yes	Yes	No
Reduced floodplain linkages	*	*	*			Yes	Yes	Yes
Cold water pollution		*			Yes	Yes	Yes	No
Snag removal		*	*	Yes	Yes	Yes		Yes
Riparian grazing	*	*	*			Yes		No
Barriers		*	*	Yes	Yes		Yes	No
Fishing	*	*	*	Yes	Yes	Yes		Yes
Exotic species	*	*	*		Yes	Yes	Yes	No