FORAMINIFERAL AND GEOCHEMICAL EVIDENCE OF ENVIRONMENTAL CHANGE IN RESPONSE TO AQUACULTURE IN THE SETIU ESTUARINE-LAGOONAL SYSTEM, TERENGGANU, MALAYSIA

In many coastal communities, aquaculture is an important part of the local economy, though fish and shrimp farms may threaten habitats in these coastal systems. Aquaculture was introduced to the Setiu estuarine-lagoonal system (SEL) in Terengganu, Malaysia in the mid-1970s. As fish farm densities increase and the mangroves are cleared, excess nutrients and fish waste are supplied to the water column and sediments below. In order for the aquaculture industry in Terengganu, Malaysia to be sustainable, there must be a limit to expansion. Analyses of foraminiferal assemblages, δ¹³C, δ¹⁵N, and C:N ratios, along with sedimentological analyses are used here to determine how aquaculture in the SEL affects benthic communities, sources of organic matter, and grain size and sediment composition. Three cores were collected beneath fish cage sites, two (SET11-S43 and SET11-S40) from the northern lagoon region and one (SET11-S9A) from the southern estuary region. Cores SET11-S43 and SET11-S40 contain both calcareous and agglutinated foraminifera, though calcareous are dominant. Ammonia aff. A. aoteana and Ammobaculites exiguus are the most abundant species in SET11-S43 and stained (live at the time of collection) specimens extend to 26 cm. Ammonia aff. A aoteana and Sagrinella lobata are most abundant in SET11-S40 with stained specimens extending to 18 cm. Core SET11-S9A contains only agglutinated foraminifera, with Ammobaculites exiguus, Miliammina fusca, and Trochammina amnicola as the most abundant species. Stained specimens extend to the bottom of the core (30 cm). The percent of carbon, nitrogen, and organic matter content (loss on ignition) increase through time throughout SET11-S43 and SET11-S40. Throughout SET11-S9A, these same measurements first increase through time but then decrease, probably corresponding to the abandonment of farm practices. Preliminary grain size analyses show patterns that mirror those of carbon, nitrogen, and organic matter content in all three cores. In summary, aquaculture has affected organic matter content and sediment characteristics in the SEL, and preliminary data indicate correlative variations of foraminiferal assemblages.