Influence of turbidity regime on larval settlement patterns of stony coral Pocillopora damicornis in Polhena reef, Sri Lanka
P.B. TERNEY PRADEEP KUMARA
Coral population structure is determined mainly by the larval settlement and recruitment pattern of sclerectenian corals. This pattern is mainly influenced by various environmental parameters such as temperature, pH, salinity, depth, current velocity and direction, tidal variations and turbidity. Experiments reported here examine the impacts of turbidity on the spatio-temporal distribution patterns of larval settlement of Indo-Pacific coral, Pocillopora damicornis at Polhena reef of Southern Sri Lanka. The experiment was conducted in four sites. Depending on the topography and the characteristics of the reef substrate each site was further divided in to three locations as reef crest, mid reef flat and reef lagoon. Terracotta tiles were attached to quantify larval settlement rates. Tiles were retrieved in monthly intervals and observed for P. damicornis larval settlements. Turbidity measurements were taken from the same locations. Larval settlement and turbidity showed a significant temporal (P<0.05) and spatial variation (MDS stress<0.1). The highest settlement rate and turbidity level were observed in May and March respectively. A significant relationship was observed between larval settlement pattern and sedimentation regime (RELATE test, = 0.251, P<0.05).