Benthic invertebrates comprise an important component of estuarine and marine and ecosystems*. Benthic invertebrates are often close to the base of the food chain, and are relatively quick to respond to environmental changes. Impacts on invertebrate communities may result in a 'trophic cascade,' which affects other elements of an ecosystem. Benthic invertebrates are therefore are a useful tool to detect the early stages of ecosystem decline. Surveys of benthos are commonly used to assess the extent of an environmental impact, or to provide an indication of aquatic ecosystem health and functioning.

FRC has applied its specialist knowledge of benthic invertebrates in a large number of projects, often in conjunction with the monitoring of other environmental parameters such as water and sediment quality, mangrove and seagrass health, and phytoplankton community structure. Recent projects include:

Navy User Requirement Options Study - Phase 3: Assessment of Benthic Invertebrate Communities, Evans Head & Broken Bay

FRC described the benthic invertebrate communities associated with three areas of seabed, two off Evans head, northern NSW, and one off Broken Bay (Sydney). These areas were short-listed as potential Navy Training Areas. Each area supports a diverse but very sparse community dominated by echinoderms, crustaceans and molluscs. The community at each area is likely to be representative of that present up and down the coast for several tens of kilometres in similar depths. Information obtained during the surveys was used to contribute to an options analysis for site selection.

Coombabah Lake and Creek Environmental Inventory - Benthic Fauna Study, Gold Coast City Council

FRC Environmental was responsible for the design and implementation of a benthic invertebrate survey of the estuarine reaches of the Coombabah creek system, incorporating Coombabah Lake. The survey resulted in the sampling, identification and enumeration of a diverse range of invertebrate taxa; and the interpretation of these results in terms of environmental influences (including environmental instability and sediment contaminants).

Weinam Creek Water Taxi Terminal EIS - Ecology and Fisheries, Redland Shire Council.

FRC undertook all ecological studies to assess the potential impacts of the proposed new water taxi terminal at the mouth of Weinam Creek (Redland Bay). Studies comprised intertidal and shallow subtidal floral communities, benthic fauna of the soft sediments, regional fishes and fisheries and wader birds.

Contaminant Assessment, Port of Brisbane.

Concerns that port activities may have been responsible for the reported decline in benthic invertebrates to the north of the river, led to the commissioning of FRC to survey and assess the abundance, diversity and health of benthic macroinvertebrates and seagrasses around the Fishermen Islands and on the intertidal flats to the north of the river. FRC's studies concluded that the Port was not a contributory factor in the reported declines.

Baseline Survey and Monitoring of Estuarine Ecosytems, Bowen, Hamilton Prawn Farm.

FRC is undertaking the assessment and monitoring of the environmental impacts of this prawn farm on the surrounding estuarine ecosystem. Benthic invertebrates, in conjunction with other techniques were used to monitor changes to intertidal communities in the vicinity of the effluent discharge. This monitoring program was designed to be statistically rigorous, meeting predetermined power and error criteria.

Sandgate Waste Water Treatment Plant Upgrading EIS, Brisbane City Council.

FRC evaluated the potential impacts of the proposed upgrading of the Sandgate Water Treatment Plant on Cabbage Tree Creek and nearby Moreton Bay. The flora and fauna of the surrounding area were described and surveys undertaken of the benthos, phytoplankton and the d15N isotope signatures of mangroves. Benthic invertebrate and phytoplankton diversity were low and typical of nutrient rich systems. The toxic raphidophyte Heterosigma akashiwo was identified in the study area.

Cedar Grove Weir EIS, Logan River, Dept. Natural Resources

The proposed construction of a weir above the tidal reaches of the Logan River required an environmental appraisal of the rivers aquatic macrophytes, benthic invertebrates and finfish. FRC undertook field surveys, including a netting program to characterise the river's aquatic flora and fauna, and to assess their sensitivity to the impacts of altered stream flow, altered habitat, and water quality. FRC also contributed to an EMP designed to minimise and mitigate the impacts of weir construction and operation. The need for a fishway to be incorporated into the weir design, and the design of a protocol to monitor the effectiveness of the fishway were key elements.

Minjerribah Planning & Management Study. Redland Shire Council / Quandamooka Land Council.

The study was a joint process in which the major elements determining the form, structure, management conservation and development of Stradbroke Island within the context of Moreton Bay are considered together, and viewed in a longterm, holistic and ecologically sustainable perspective. FRC undertook the marine and estuarine components of this study. Habitats and communities investigated included saltmarsh, mangrove, seagrass, macroalgae, benthic microalgae and phytoplankton, epi-benthic, in-benthic and pelagic invertebrates, finfish, wader birds marine reptiles and mammals. Ecological communities of particular conservation significance were identified and issues involving traditional owners present use discussed.

*FRC also offers expertise in the use of the AUSrivas protocol for assessing ecosystem health using freshwater macro- invertebrates; see Capabilities Statement 'Freshwater Macro-Invertebrate Monitoring'.