Comparisons of benthic filter feeder communities before and after a large-scale capital dredging program
Muhammad Azmi Abdul Wahab1, Jane Fromont2, Oliver Gomez2
1Australian Institute of Marine Science, Indian Ocean Marine Research Centre, The University of Western Australia (M096), 35 Stirling Highway, Crawley, WA 6009, Australia; Western Australian Marine Science Institution, Entrance 2 Brockway Road, Floreat, Western Australia 6014, Australia.
Marine Pollution Bulletin
|July 2, 2017
Summary
Capital dredging in Onslow, Australia, increased turbidity and sedimentation, impacting light levels. Sponge communities persisted, suggesting pre-existing environmental adaptations may have aided resilience.
Area of Science:
- Marine biology
- Environmental science
- Coastal ecology
Background:
- Onslow, northwestern Australia, is a biodiverse region with 150 recorded sponge species.
- The area experiences naturally high turbidity, influenced by the Ashburton River discharge.
- Filter feeders, particularly sponges, are sensitive to changes in water quality.
Purpose of the Study:
- To quantify changes in turbidity, sedimentation, and light during a two-year capital dredging program.
- To assess the effects of dredging on sponge communities in Onslow.
- To understand the resilience and adaptive capacity of sponge communities to anthropogenic disturbances.
Main Methods:
- Towed video surveys to assess community functional morphological composition.
- Dive surveys to determine species composition and chlorophyll content.
- Monitoring of turbidity, sedimentation, and light levels before, during, and after dredging.
Main Results:
- Turbidity and sedimentation increased by up to 146% and 240% respectively due to dredging.
- Light levels decreased correspondingly with increased turbidity and sedimentation.
- Sponge communities exhibited persistence despite dredging impacts, with no pronounced negative response observed.
Conclusions:
- The sponge communities in Onslow demonstrated resilience to the capital dredging program.
- Environmental filtering or pre-existing adaptations may have contributed to the observed sponge persistence.
- Further research is needed to fully understand the long-term effects of dredging on marine ecosystems.
Related Concept Videos
01:30Marine Microbial Ecology
Marine microbial ecosystems are shaped by distinct physicochemical limits, including high salinity, low nutrient availability, and fluctuating oxygen levels. These conditions favor smaller microbial cell sizes, which maximize their surface-to-volume ratio for efficient nutrient uptake.Microbial activity and community composition are closely linked to biogeochemical cycles, particularly in dynamic environments like estuaries, where halotolerant microbes thrive in response to variable salinity...
01:24Freshwater Microbial Ecology
Freshwater systems such as streams, rivers, and lakes exhibit distinct physical and biological characteristics that influence their microbial communities. These environments are broadly categorized into lotic systems—those with flowing waters like streams and most rivers—and lentic systems, which include still or slow-moving waters such as lakes, ponds, and marshes.In lentic systems, phytoplankton drive primary production, generating autochthonous organic carbon. In contrast, lotic systems...