Effects of fragmented mangroves on macrozoobenthos: a case study of mangrove clearance for powerline right-of-way at Oproama Creek, Niger Delta, Nigeria

Abstract

Mangroves are vulnerable to varying magnitudes of degrading impact by human activities. Despite the many benefits of mangrove ecosystems, mangroves in the Niger Delta region are often cleared for electric powerline and oil pipeline rights-of-way, recreation, road construction, housing and farming. The study assessed the impacts of mangrove clearance on physico-chemical parameters of interstitial water and macrozoobenthic primary community structure in Oproama Creek, Nigeria, from February to July 2016. Three stations were selected for the study: two stations in more natural and undisturbed mangroves and one station at a mangrove clearing (for a national grid powerline right-of-way). Species richness and diversity were slightly higher at the undisturbed mangrove sites than the cleared site. Removal of mangrove canopy shade alters microclimate temperature regime and other temperature-dependent parameters, imposing thermal stress on stenothermal taxa and ancillary stressors that compositely affected primary community structure indices. Deliberate loss of mangroves through clearing waterfront vegetation as a driver for improved visual monitoring and enhanced security in the Oproama Community in the Niger Delta is reported for the first time. The wider implications of mangrove clearance and fragmentation on ecosystem-based goods and services are discussed. Limiting mangrove spatial loss owing to construction of an electric tower cutline within coastal landscape is strongly recommended.