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Capabilities: Seagrass, Mangrove and Saltmarsh
Coastal wetlands: seagrasses, mangroves and saltmarshes contribute significantamounts
of vegetable matter to the food chain; trap, accumulate and release nutrients
(and in some cases pollutants) and sediments; provide a habitat or shelter
to a range of fauna and flora; and protect the shoreline from erosion.
Recent research has shown the close dependence of many species of commercial and recreational fish and crustacea upon coastal wetlands, particularly seagrass meadows.
The distribution and health of each of these floral communities may be influenced by a range of environmental factors. Saltmarsh and mangroves may be degraded by filling of coastal lands, and altering drainage and the salinity of soil water; seagrasses, by increased turbidity (reducing light required for photosynthesis), and nutrient enrichment encouraging phytoplankton and macroalgal growth. Clearly, it's not only coastal development that may impact upon these communities, but also development within the broader catchment.
FRC is a leader in the field of seagrass, mangrove and saltmarsh survey, monitoring and rehabilitation.
Recent studies undertaken by FRC scientists include:
There was a community concern that the construction of a dredge material disposal and handling area at Urangan may impact the extensive seagrass beds nearby. To monitor potential impacts on these beds Queensland Transport, with assistance from DPI Fisheries and FRC established 'Seagrass Watch' sites. FRC undertook the ongoing training of volunteers and audited the monitoring for this project.
Impacts of a proposed crossing over Weyba Creek were assessed, with particular attention to the impact of shading on mangroves and seagrasses. Light attenuation under similar bridges and in mangrove forests was measured and compared to literature values of the light requirements of mangroves. A variety of options for the proposed bridge were considered through extensive workshops with Queensland Fisheries Service, Noosa Shire Council, Department of Natural Resources and Mines, Department of Main Roads and the bridge design engineers.
FRC is undertaking the assessment and monitoring of the environmental impacts of this prawn farm on the surrounding estuarine ecosystem. Benthic invertebrates, cover of epiphytic algae on mangrove roots, seagrass distribution and the d15N isotopic signature of seagrass, mangroves and algae in the vicinity of the effluent discharge and in nearby control creeks are monitored. This monitoring program was designed to be statistically rigorous, meeting predetermined power and error criteria.
During the construction of the Queensland Fire and Rescue Authorities training facility at Whyte Island some estuarine vegetation was damaged. FRC assisted Basic Construction Services and QFRA in their liaison with the Queensland Fisheries Service and the Port of Brisbane Authority. FRC advised on site works to rehabilitate the wetland and designed a vegetation and management plan for the buffer zone, using local species. FRC then undertook monitoring of the regrowth of the estuarine vegetation as required by QDPI.
FRC contributed to a multidisciplinary study to develop a system for objectively assessing the conservation value of 218 coastal wetlands throughout southern Queensland. Wetllands were classified according to their conservation significance, presence of conservationally and culturally significant species size, connectivity, habitat diversity and species diversity.
The planned redevelopment of the Cairns Esplanade, Trinity Wharf and associated marinas requires a substantive EIS. FRC is responsible for the assessment of impacts relating to all aspects of aquatic flora and fauna including: mangroves, seagrass, benthic invertebrates, fishes, and avifauna. FRC is also designing an environmental monitoring program against which impacts may be measured, and is contributing to the project's Environmental Management Plan.
FRC assessed the ecological and conservational significance of inter and subtidal flora and fauna communities from local, regional and state perspectives. The nature and level of threat to biological diversity and ecological integrity was also assessed.
The inshore distribution of seagrass at Upstart Bay, Cleveland Bay, and south of Lucinda were surveyed for the QCFO. A combination of aerial photographic interpretation, low level aerial survey and field surveys on foot and by boat were used to determine the present distribution. The distribution, abundance and biomass of each species was recorded, and compared to previous distributions.
Having designed an environmental monitoring program to assess the impact of residential development on adjacent aquatic flora as a component of the project's EIS, FRC were commissioned to undertake baseline and annual monitoring studies. These studies comprised the mapping of aquatic flora; the description of community composition, and the determination of distribution relative to environmental factors.
The redevelopment of Toondah Harbour, including the enlargement of the existing harbour and associated navigation channels, required a detailed appraisal of intertidal and subtidal faunal and floral communities (mangroves, seagrass, macroalgal communities and associated benthic fauna) likely to be impacted by the redevelopment; comment upon the characteristics of likely impacts; and recommendations for mitigating measures.
As a permitting requirement, studies were undertaken relating to the intertidal and subtidal flora and fauna, on and adjacent to the route of the proposed water supply pipeline. Key elements considered included saltmarsh, mangrove, seagrass and macroalgae communities. An assessment of the likely impacts to each community developed, together with recommendations for environmental management of the required dredging and installation works.
Runoff and sediment from a gypsum stockpile destroyed a large area of mangroves on Boggy Creek near the Brisbane River. The principle causes of death were assessed and rehabilitation of the mangroves, by seed and seedling transplantation undertaken.
The objective was to provide indicators and predictors of environmental degradation associated with urban and rural development. Characteristics of seagrass distribution, density and health, together with sediment and pore water nutrient concentration were monitored. Factors responsible for the 'die-back' of seagrass within the region were also investigated, and the implications of the fluctuations in seagrass abundance on endangered species such as dugong and green turtle, and upon the commercial fishing industry assessed.
FRC's Carol Conacher was involved with research on the rehabilitation of seagrass beds in Moreton Bay undertaken by CSIRO. The focus of this work was to establish cost efficient and effective means of re-establishing seagrass beds. Rehabilitation was trialled on a large scale using a 20 tonne amphibious excavator, and on smaller scales using pots of seagrass. These studies were undertaken in collaboration with a number of industrial partners including Leighton Contractors Pty. Ltd and the Port of Brisbane Authority.
This study, commissioned as a component of the client's review of it's strategic plan, considered the distribution, character and ecological significance of a range of coastal habitats: frontal dunes, mangrove, saltmarsh, seagrass, Melaleuca, coastal rainforest and freshwater rushlands. The survey also identified existing and potential threats to the integrity of conservationally significant habitats, and offered management measures to ensure their protection.
FRC's Carol Conacher pioneered techniques for the cost effective re-establishment of mangrove communities. Carol was responsible for developing techniques for both large and small scale rehabilitation projects. Field trials undertaken in collaboration with industry, local government and conservation groups, attest to the success of the techniques developed.
Working with the study group's engineers, FRC undertook a survey of the mangroves of the mid-reaches of the Brisbane River, determining their ecological significance and sensitivity, and assessing their susceptibility to impact from the wake of the proposed 'Jaguar' high speed ferries.