DETERMINING THE IMPACTS OF AQUACULTURE ON THE SETIU ESTUARY AND LAGOON OF TERENGGANU, MALAYSIA USING FORAMINIFERA, SEDIMENT GRAIN-SIZE, AND STABLE CARBON AND NITROGEN ISOTOPE RATIOS

The Setiu wetland, located along the northeast coast of Malaysia and separated from the South China Sea by a narrow barrier island system, is one of seventeen priority conservation sites in the Malaysian Wetland Directory. However, in the 1970’s, a local fish farm industry was established in the Setiu estuary and lagoon and has continued to grow and spread into the surrounding mangrove forests, which are being increasingly cleared. As a result of these fish farms, nutrients, antibiotics, pesticides, fish food and fish waste are being emptied into the wetland system, potentially putting a stress on the environment.

We are using a multi-proxy approach (foraminifera, sediment grain-size, carbon and nitrogen isotopic ratios) to address the environmental effects of the fish farms. The current distribution of benthic foraminifera, closely related to variations in salinity, sediment grain-size and other variables related to the hydrodynamics of the region, has been documented and these data provide a baseline for monitoring future change in estuarine/ lagoonal environments. Push coring adjacent to floating fish cages indicates that the substrate prior to the initiation of aquaculture was medium to coarse-grained sand whereas the substrate beneath the cages is currently organic –rich mud, as determine by loss on ignition, with little sand, suggesting that the fish cages are directly impacting sedimentation, organic matter flux, and oxygen demand. Side scan sonar data indicate that the muddy substrate extends up to 10s of meters from the cages. Preliminary carbon/ nitrogen data exhibit distributional patterns that correlate with the distribution of the fish cage mud. Future work will document the foraminiferal characteristics of this mud and compare the results to the baseline foraminiferal data.