Evaluation of coral and non-coral community structure and water quality of the southern coast of Kayankerni Marine Protected Area, Batticaloa, Sri Lanka

Abstract

Kayankerni Marine Protected Area (MPA), located on the south-eastern coast of Sri Lanka, supports ecologically important coastal habitats, including coral reefs and associated benthic communities. This study aimed to quantify coral and non-coral benthic cover and document selected physio-chemical water quality parameters at designated sampling stations within the MPA. Benthic composition along a 1.5 km shoreline was assessed using systematic transects and underwater photographic sampling, and analyzed using Coral Point Count with Excel extensions (CPCe, version 4.1). Five major transects for every 300m shoreline (each 50m perpendicular to the seaward) were established. Among these, major transects 3 and 4 were divided further into six systematic sub-transects (each 200m perpendicular to the seaward). A total of 30 point-count stations were evaluated within the six sub-transects. Both the Small Polyp Stony (SPS), Acropora and Montipora of Scleractinian corals were observed in the study area but, Montipora only found outside the transects. Mean coral cover of Genus Acropora was estimated at 36.34%, while non-coral components such as coral rubble and algal categories especially Padina sp., comprising a substantial proportion of the non-coral cover for remaining. Water quality parameters, including pH, electrical conductivity, salinity, and turbidity (7.95 ± 0.11, 50.34 ± 0.24 mS, 4.3 ± 0.03 Brix %, and 0.62 ± 0.045 NTU, respectively), were within ranges generally reported for coastal reef environments. Also, the observed Acropora, was in highly bleached state which may due to environmental stressors, primarily elevated sea temperatures which needs to be further studied. The findings provide a quantitative baseline of coral cover, benthic composition, and water quality conditions in the Kayankerni MPA, which may support future monitoring and management initiatives aimed at sustaining reef-associated biodiversity.