Nutrients impacts on the abundance of plankton in Penaeus monodon (Fabricius 1798) shrimp ponds at Dumuria, Bangladesh

摘要

This study was carried out to understand the effects of addition of supplemental feed nutrients such as high protein (feed 1) and low protein (feed 2) diets on the natural food web in twelve tiger shrimp (Penaeus monodon) ponds at Dumuria of Khulna district, Bangladesh. During this study, water temperature ranged from 32.23 - 32.61oC and 32.29 - 32.44oC in case of feed 1 and feed 2 treated ponds respectively. On the other hand, salinity, pH and transparency were more or less stable and similar in both treatment ponds. In high protein supplemented feed 1 ponds, dissolved oxygen (DO) varied from 5.51 - 5.68 mg/l and in low protein feed 2 ponds, DO varied from 5.53 to 5.67 mg/l. During this study period, 13 taxa of phytoplankton under six classes were recorded. Most dominated class was Coscinodicophyceae (42.02% in feed 1 and 42.26% in feed 2 ponds) whereas minimum quantity of phytoplankton belonged to the class Dianophyceae (1.86 and 2.17%). On the other hand, a total of 29 taxa of zooplankton under 3 groups were recorded. In ponds treated with feed 2 phytoplankton abundance was slightly higher than that of ponds treated with feed 1. Whereas, abundance of zooplankton was higher in ponds treated with feed 1 than in ponds fed with low protein feed 2. As phytoplankton is the important factor for the production of zooplankton and also for natural food web, any addition of feed was found to be improving nutrients and enhancing the natural productivity of tiger shrimp ponds.