Composition, density and spatial distribution of zooplankton on 1st transition season (March to May) in Inner Ambon Bay Waters, Indonesia

Abstract

Inner Ambon Bay is part of Ambon Bay that covered an area about 11.03 km2. It is semi-closed and become a small pelagic fish fishing ground, especially anchovy. The anchovy is a zooplankton predator, hence, the abundance of anchovy is dependent on the abundance of zooplankton. The research aims to analyze the composition, density, and spatial distribution of the zooplankton during the 1st transition season (March to May). Data of zooplankton composition were attained from sampling by using plankton net at ten observation stations, meanwhile, data of densities were obtained using a scientific hydroacoustic system on six parallel transect lines and one cross-parallel transect line. The study shows that the zooplankton community is dominated by Copepod and meroplankton. The highest density was found in March, while the lowest density was in April. Vertical distribution of zooplankton shows that the highest density was found near the surface (0-4 m) and decrease to a deeper water column. On the horizontal distribution, lower densities (0 – 400 ind./m2) occupy a wider area, they are evenly distributed in western, middle, and eastern, in the contrary, higher densities (3,000-4,000 ind./m2) occupy smaller space viz. in the southwest and east of Inner Ambon Bay.