Peri-urban Mangroves of Dar es Salaam-Tanzania are Highly Vulnerable to Anthropogenic Pressures

Makemie J. Mabula, Mwita M. Mangora, Christopher A. Muhando

Institute of Marine Sciences-University of Dar es Salaam. P. O. Box 668- Zanzibar.

Abstract: Increasing demand for socio-economic services and infrastructure developments, exert multiple pressures on coastal and marine resources, especially mangroves that occur on the outskirts of Dar es Salaam city. The study therefore assessed and mapped the anthropogenic threats and vulnerability of mangroves at Kunduchi and Mbweni. The threats were identified and validated through field observations before they were mapped in Google Earth (GE) images. Major threats were ranked on the basis of their persistence and proportional area of mangrove forest modified. The mangroves were also ranked on the basis of their proximity to the major threats. These threat and mangrove ranks were then spatially integrated using ArcGIS to develop mangrove vulnerability maps. Normalized Vegetation Index (NDVI), proxy indicator for mangrove vegetation health, was analysed from 2014 Landsat 8 image in QGIS. GE images of 2003-2014 were analysed in ArcGIS for mangrove area change detection. The major human threats at Kunduchi were the salt works and settlement, whereas at Mbweni were settlement and trampling. Analysis of the 2014 GE images indicated that Kunduchi and Mbweni had 157.3 and 42.1 ha of mangroves, respectively. About 40% and 31% of the mangroves at Kunduchi and Mbweni respectively, were vulnerable to anthropogenic pressures. There was a net gain of 12.0 ha at Kunduchi and 0.7 ha at Mbweni during the period of 2003-2014. Effective control measures are required to regulate human pressures and protect these mangroves. Promotion of incentive based conservation schemes like community-based payment for ecosystem services is one of the plausible options to explore.

Keywords: Mangroves, Athropogenic pressure and Vulnerability.

Pages: 141 – 172 | Full PDF Paper