Comparative Ecological Study Of The Nyan And Kakum Estuaries, Ghana
Abstract
This study aimed at comparing the ecological characteristics of the Nyan and Kakum estuaries in Ghana. Monthly data on hydrographic factors, sediments and benthic macroinvertebrates were collected at low tide from August 2011 to July 2012 from three stations in the Nyan estuary, and four stations in the Kakum estuary. Seasonal variations were observed in all hydrographic
factors, except water depth in both estuaries. In both estuaries, bottom salinity was higher than the surface and middle as in positive estuaries. Sediment mean particle sizes determined by graphical and calculation methods were similar. Coarse sand dominated the sediments in both estuaries. Humus content of the sediment was consistently low at the mouth of both estuaries
(0.12 – 0.66 %). Out of the total of 45 and 40 species encountered in the two estuaries, annelids and crustaceans dominated. Nereis sp., Capitella capitata and Cossura sp. were the pollution-tolerant species while Scoloplos sp. and Amphiglena sp. were the pollution-sensitive species encountered confirming the biomonitoring potential of benthic macroinvertebrates in the two estuaries. The macroinvertebrate communities of the two estuaries were similar with Sorensen’s index of 0.517 – 0.764. The apparent low species diversity and richness in both estuaries is attributed to the stresses associated with estuarine systems. It is recommended that a checklist of macroinvertebrates of major water bodies in the country be produced and a pollution index developed for the assessment of ecological integrity of water bodies.