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Occidental College

Publication Date

Fall 2017

Program Name

Tanzania: Wildlife Conservation and Political Ecology


This study assessed the density and diversity of crabs across three mangrove forest zones in Ushongo, Tanzania. The aim was to understand variance in the composition and distribution of mangrove crabs in relation to mangrove tree composition gradients in the area. Sites were measured using a 200m line transect and 40-plot method. Data was also collected from a sand beach habitat to compare to the diversity and distribution of mangrove habitats. Diversity was analyzed using Simpson’s Index of Diversity and an ANOVA test on the average number of species found per plot in each site. Density was analyzed using an ANOVA test on the number of crab individuals recorded per plot in each site. Site 1 was located on the Ushongo Rive estuary, and had the highest diversity in composition of crabs and mangrove trees. Site 2 was a homogenous stand located near Ushongo Mtoni, which had the highest abundance of crab species which indicated specialization. Site 3 was located near Ushongo Mabaoni and had the lowest diversity and highest amount of human disturbance. Overall, the study found that there was significant variance in crab composition and distribution between the three mangrove sites, which indicates correlation between crab and mangrove tree gradients. Crab studies such as this one, can be used to assess mangrove forest composition and health. Furthermore, comparison to the Sand Beach Site indicated the uniquely important biodiversity that mangrove forests support, which should continue to be monitored conserved. This information is important for use in future ISP studies and for village leaders and conservation organizations to access for future mangrove conservation plans in the area.


African Studies | Animal Sciences | Biodiversity | Environmental Indicators and Impact Assessment | Forest Sciences | Marine Biology | Natural Resources and Conservation | Oceanography | Terrestrial and Aquatic Ecology


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