The Status of Water Quality in Various Fish and Shrimp Farms of Sindh Province, Pakistan: Abundance of Planktonic Biomass in Relation to Physicochemical Properties of Pond Water

Abstract

This research aims to study the water quality of 10 fish farms located in different regions of Sindh and to suggest a guideline for favorable physicochemical parameters for fish and shrimp farming. Water samples (n = 3 each) were collected from these farms and analyzed for contents of ammonia, alkalinity, temperature, nitrate, salinity, nitrite, pH, total hardness, dissolved oxygen (DO), chlorophyll-a and phytoplankton-density during the period from March, 2015 to June, 2016. The chlorophyll-a concentration was determined by using the acetone extraction technique. Ponds water sample (50 liters) was filtered through plankton net of 20 jam pore size and preserved in 4% formaldehyde for the analysis of phytoplankton. Subsequently, the phytoplankton were counted under microscope. Result showed that water quality parameters of all fish farms were suitable for farming purpose excluding Shamimul Hassan Farm, Fish Farm Green Co. and Ghulam Ali Nizamani Farm, where high level of total hardness was recorded as 1000±2.65 mg l-1, 700±4.80 mg l-1, and 975±4.73 mg l-1, respectively. The minimum chlorophyll-a (1.4-2.1 mg l-1) was found in the ponds water of Shamimul Hassan Farm, Fish Farm Green Co., and Ghulam Ali Nizamani Fish Farm, although the remaining farms showed maximum values 5.8-7.5 mg l-1. Similar trend for the minimum (2.3 x105 cells 1-1) and maximum (13.2 x105 cells 1-1) concentration of phytoplankton cell density was also found in all the ponds, representing a strong correlation (P>0.05) between chlorophyll-a and phytoplankton cell density. Significant correlation (P>0.05) was also found among temperature, pH, salinity, nitrite, nitrate, ammonia, alkalinity, total hardness, chlorophyll-a and phytoplankton-density. Eigenvalues of the first two principal components represented 99.97 % of the total variability in water quality of fish and shrimp ponds at different farms. Positive loadings indicated high contribution of water quality variables throughout the study period.