Phytoplankton Saprobity as Pollution Bioindicator: A Study of Genera Chaetoceros in Port of Tanjung Emas Waters, Semarang

Abstract

Water fertility is an assessment of the condition of organism diversity in relation to aquatic ecosystems. PTES (Port of Tanjung Emas, Semarang) is a major port in Java Sea waters and a domestic port for commercial vessels. Its water condition is influenced by the activities of both commercial and fishing vessels. This research applied a descriptive method with cluster sampling, including a group of samples in the port pool and samples from outside the port pool as a control station (comparator). The research aimed to analyze pla nkton fertility through the analysis of plankton abundance (N) and analyze factors that support the fertility of the waters, such as physicochemical parameters. In this research, diatoms ( Bacillariophyceae ) were found as a class that dominated in the waters with a dominance rate of 95%, meaning that the waters were in β-mesosaprobic condition (moderately polluted). The novelty of this research was the finding of toxic Chaetoceros , which dominated in the waters, resulting in the disappearance of other genera and lower organism abundance and diversity at a higher level. This abundance was a bioindicator that triggered heavy pollution (α-mesosaprobic). Regression analysis showed that phytoplankton abundance was determined by brightness, nitrate, turbidity, and zooplankton abundance. Using factor analysis, there were five factors that affected the total saprobic index (TSI); the largest factor was influenced by the first components (41.49%), including salinity, brightness, temperature, pH, DO, nitrate, and SI. Keywords: Port of Tanjung Emas, water fertility, total saprobic index, factor analysis, physicochemical parameters. https://doi.org/10.55463/issn.1674-2974.50.4.11