Effects of Seismic Exploration on Mangrove Habitat in Tanzania

Abstract

Abstract—Global demand for oil and gas has resulted in increased seismic exploration for new resources in environmentally sensitive areas. Reports of damage to ecosystem function have been reported, but the environmental effects of seismic exploration are largely undocumented. Key impacts in mangroves include tree removal and trampling. This paper reports on their effects in southeast Tanzania, through assessments of tree density and species distribution, incidence of local harvesting and changes in environmental conditions that might influence the biota. Seismic survey-related gaps in the canopy have not resulted in increases in mangrove recruitment, or affected microhabitat temperatures or salinity. However, seismic lines may have become access routes, leading to increased mangrove harvesting. There were few signs of recovery in the immediate vicinity of seismic lines, which appeared to be related to trampling effects on soil stability and changes in hydrology attributable to the loss of trees. Future research should target seedling and sapling abundance and growth rates, and soil structure, composition and nutrient levels. Recommended mitigation measures would involve the promotion of mangrove regeneration and the prevention of secondary impacts such as the use of lines as access routes, with monitoring of forest recovery.

Keywords: Mangrove, recovery, oil exploration, seismic survey, Mnazi Bay Ruvuma Estuary Marine Park, Tanzania, East Africa.