Nutrients and chlorophyll-a concentration in Socah Estuary receiving shrimp pond waste, Bangkalan Regency

Abstract

This study investigates the nutrient content, water quality, and its relationship with chlorophyll-a in the Socah Estuary, Bangkalan Regency. The research was conducted in four stations. Determination of nitrate and nitrite in samples was performed by the colorimetric method. Meanwhile, phenate and Nessler reagent spectrophotometric methods were used to determine the ammonia and ammonium content in samples, respectively. The phosphate and chlorophyll-a were determined using ascorbic acid and spectrophotometry, respectively. The Spearman rank correlation was used to measure the degree of relationship between nutrients and chlorophyll- a content. Based on the results of Spearman rank correlation, the nitrate showed the strongest correlation (rho = 0.76) compared to other nutrients. Moreover, the increased chlorophyll-a level in the water will be closely related to the increased nitrate level. According to the value of Secchi depth, nutrients, and chlorophyll-a concentration, eutrophic is a trophic state in Socah Estuary. This condition is caused by the input of shrimp pond wastewater which triggers nutrient enrichment, decreasing the water quality and increasing the phytoplankton biomass in Socah Estuary.