Bioremediation Mariculture in Zanzibar, Tanzania: A viability assessment of using bath sponge and pearl oyster farms to filter highly polluted waters in the Zanzibar Channel

Abstract

Bioremediation of polluted water off the coastline of the urban center of Zanzibar—Stone Town, Unguja—was assessed for implementation feasibility through bath sponge and pearl oyster mariculture. A vast research base of the city’s coastal area exists, including the pollution concentrations at various locations, the ramifications of this pollution on the fringing ecosystems, and the relevant water circulation system of eddies and passageways produced by the north flowing East African Counter Current. In following the experimental examples of bioremediation projects around the world, this study tested facets of the filtration abilities of marine sponges and oysters. Both organisms suggested strong pollution filtration abilities. Phosphate concentrations decreased from an average of 3.93 ug/L (micrograms per liter) to 1.33 and 1.73 ug/L for sponges and oysters, respectively. Unique capabilities of each organism were displayed in the experiments. The marine sponges visibly eliminated the turbidity level in the 36-hour study period. The marine oysters were suggested to chemically convert the dissolved nitrates through the tested increase in ammonium concentration from an average of 4.01 ug/L in the contaminated water to and average replicate concentration of 21.5 ug/L. The respective mariculture techniques were examined along with management logistics to assess the viability of implementing the mariculture for the pollution remediation. It was concluded that the mariculture techniques could be feasibly established by carefully collaborating with the nature of the pollution distribution, the consultation and aid of private and governmental organizations and further background scientific research.