Home Institution

University of Denver

Publication Date

Fall 2022

Program Name

Tanzania-Zanzibar: Coastal Ecology and Natural Resource Management


Since 2009, Marine Cultures, an NGO, has explored sponge farming in Jambiani to develop secure and sustainable livelihoods for the community. While sponge farming provides economic opportunity for an industry that functions within ecological boundaries, it faces unique issues that threaten its success. As climate change increases global water temperatures, cyanobacteria are causing increased death rates among mariculture sponges. Mitigating these negative effects with sustainable and reliable solutions can help Marine Cultures grow their positive impact. Alternative methods for mitigating cyanobacteria growth were tested during three study phases. Phase 1 tested how sponge health and algae growth responds to being submerged in a range of hydrogen peroxide concentrations. Phase 2 explored how sponge health and algae growth respond to a range of submersion times in 20% hydrogen peroxide. Phase 3 focused on whether algae growth on support lines can be reduced using sustainable antimicrobial solutions of 50% clove oil, 50% lemon grass oil, and 50% hydrogen peroxide. The treatments on old ropes successfully reduced algae and cyanobacteria growth during the study period. The health of the sponges was not impacted by lower concentrations of hydrogen peroxide and shorter submersion periods. There was no conclusive outcome on the impacts of hydrogen peroxide treatment on the growth of cyanobacteria and other algae. This study provides valuable information to aid in developing tools to respond to climate change and improve sponge farming in Jambiani.


African Studies | Climate | Environmental Monitoring | Marine Biology | Natural Resources and Conservation


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