Variations in Important Water Quality Parameters and Fish Species in Thondaimanaru Lagoon, Jaffna, Sri Lanka

Abstract

Thondaimanaru lagoon is one of the shallow coastal lagoons in Jaffna peninsula. The current study was conducted to assess the present status of water quality and fish species composition of this lagoon. Water sampling was conducted from July 2016 to December 2016. Nine random samples were collected monthly in order to determine water temperature, pH, salinity, Dissolved Oxygen, Total Dissolved Solids and turbidity. A smarTROLL Multi parameter (Insitu 458389) was used to measure all the parameters except turbidity, which was measured by turbidity meter (2100Q HACH). Random samples of fishes were collected once a month. One-way ANOVA was used to perform statistical analysis. Water temperature, Dissolved Oxygen, salinity, Total Dissolved Solids and turbidity showed significant variations (p < 0.05) whereas pH value did not show a significant difference (p > 0.05) among the months. Chanos chanos, Hemirhamphus sp., Nematalosa nasus, Mugil cephalus, Liza parsia, Oreochromis mossambicus, Arius caelatus and Gerres lucidus were present throughout the study period. Results revealed that the important water quality parameters fluctuated due to seasonal environmental changes where shallow water depth of lagoon, rate of evaporation as well as precipitation had a significant influence on the water quality characteristics.