Water Quality and Plankton Dynamics as Determinants of Ecosystem Stability in Intensive Culture of Whiteleg Shrimp (Litopenaeus vannamei)

Intensive vannamei shrimp farming requires stable water quality because changes in water conditions can affect plankton abundance, which supports the ecological balance of the pond. This relationship provides a basis for managing productive and sustainable aquaculture systems. This study aimed to analyze water quality conditions, plankton abundance, and the relationship between the two in an intensive farming system of vannamei shrimp (Litopenaeus vannamei) at PT. Dua Putra Perkasa, Kaur Regency, Bengkulu, Indonesia. The study employed an observational survey method in seven intensive vannamei shrimp ponds throughout one 72-day culture cycle. We measured water quality periodically and analyzed plankton abundance through laboratory identification. We analyzed all data descriptively and comparatively to evaluate the relationship between water quality and plankton abundance. The results showed that all measured ecological parameters remained within the optimal ranges for intensive vannamei shrimp farming, including temperatures of 26.9–31.5°C, pH values of 7.5–8.2, a mean dissolved oxygen (DO) concentration of 4.6 mg/L, water transparency of 30–40 cm, and salinity of 30–34 ppt. These conditions supported shrimp physiological processes and biogeochemical activities in the ponds. NH₄⁺ and NO₂⁻ concentrations increased during several periods, indicating increasing nutrient pressure as farming intensity increased. Plankton abundance ranged from 204,000 to 440,000 cells/L and was dominated by green algae (GA), particularly Chlorella sp. and Tetraselmis sp., followed by diatoms (Navicula, Nitzschia, Bellerochea, and Chaetoceros) and minor dinoflagellates. In contrast, Cyanophyta and dinoflagellates occurred at relatively low proportions. Pond stability depends not only on water quality but also on the balance of nutrient inputs, biogeochemical transformations, and nutrient utilization by plankton. Therefore, integrated monitoring of water quality and plankton community structure is essential for maintaining the productivity and sustainability of intensive L. vannamei farming.