Assessment of some water quality parameters of three coastal water bodies towards the culture of oysters in Ghana

Abstract

Oyster culture as a supplementary livelihood for many coastal communities is a potential that is yet to be exploited in Ghana. Temperature, salinity, dissolved oxygen, pH, turbidity, bacteria (coliforms and total bacteria) and heavy metal loads are among the key environmental factors that influence the physiological wellbeing (also known as condition index) of oysters. This study investigated these environmental parameters in three coastal water bodies in Ghana and their influence on the condition index (CI) of the resident oysters, as a means of determining the suitability of the water bodies for oyster culture. Physicochemical parameters were measured in situ with different measurement tools, whereas microbial load and heavy metal concentrations were determined in the laboratory using the pour plate method and atomic absorption spectrophotometer respectively. The environmental parameters fluctuated in similar patterns in the water bodies during the study period, with values within limits that indicated good ecological health of the water bodies. The bacterial loads generally exceeded the acceptable limits, but heavy metal concentrations were within permissible limits. A linear regression analysis showed that physicochemical parameters had variable influence on the CI of oysters from the water bodies, with temperature having the strongest influence. Bacterial loads in water had variable influence on CI, but total coliform load in oysters had a positive significant influence on CI. The heavy metal concentration in water samples also had variable influence on the CI of oysters. It is concluded that all the three water bodies could be considered as suitable sites for oyster culture provided efforts are made to limit activities responsible for the high microbial load.