Oceanographic conditions and sedimentation in the Kawal river Bintan Island and impact on the prevalence of coral disease

Abstract

Abstract In river mouths and coastal areas, sediment carried by water flows often clogs the estuaries and causes silting lagoons, impacting the prevalence of coral disease. Ten sediment traps were installed in the river 25 cm from the bottom to record the data for 21 days in Kawal River. Oceanographic and current flow data were collected using CTD and a Current meter using the Eulerian method with a depth interval installation of 0.25 to 0.75 from the river surface. The Underwater Photo Transect (UPT) is a method to analyze the condition of coral reefs and coral disease. CTD the temperature data ranged from 30.471 ± 0.001 °C to 31,609. ±0.001°C, salinity value ranges from 29.643 ± 0.001 PSU to 32.336 ± 0.001 PSU and current flow ranged from 0.063 ± 0.010 m/s to 0.281 ± 0.012 m/s. The results of the sediment trap, the dry weight value of sediment deposited in the sediment traps ranges from 0.89 grams, and for the largest of 48.45 grams, the turbidity ranged from 0.77 NTU to 4.22 NTU. The prevalence of coral disease was 56.40%. The conclusion indicates that excessive sedimentation rates at river mouths can result in a high incidence of coral disease.