Frontier-Tanzania Environmental Research REPORT 103 Misali Island

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Misali Island: A detailed description of the subtidal regions1.4 MISALI ISLANDThere are no permanent inhabitants of Misali Island, although the Rangers who patrolthe Misali Island Marine Conservation Area (MIMCA) remain on the island for arotational period of 365 days per year and fishermen camp there for approximately twoweeks each month. The island is about 0.9km 2 in area and constructed of coral rag,therefore much of the vegetation consists of coral rag forest and coral rag bush orcoastal thicket (Cooke 1997). There are some mangrove stands scattered around theintertidal areas of the island, but also in small stands within its interior (pers. obs.2001). There is a relatively large fishing practice associated with the island's watersand intertidal region relative to it’s area (Arnold 1997, Cooke 1998, Richmond &Mohammed 2001, pers. obs. 2002).All the surveys discussed in detail within this report relate to subtidal assessmentsundertaken by SCUBA techniques. There have previously been limited surveysconducted around Misali Island and therefore a paucity of data for its marine resources:abundance and diversity of fish; location of, composition of and damage extent to thecoral reefs; invertebrate diversity and distribution. Such information is important togather in terms of assessing regional biodiversity and essential to incorporate intofuture management plans.1.5 FRONTIER-TANZANIA MARINE RESEARCH PROGRAMME AIMS1.5.1 FT MRP Aims• To assess the marine resources within Pemba, and provide technical advice asan input to management planning and decision-making• To conduct training for fisheries officers, local resource users, students from theInstitute of Marine Sciences (IMS), the University of Dar es Salaam (UDSM),and Misali Island Conservation Project (MICP) personnel• To work with community representatives and teachers to increase theenvironmental awareness of the coastal communities of Pemba.These activities and resulting information will assist with recognition of the biologicaldiversity of the area. They also aim for a comprehension of the distribution of habitattypes and associated fauna to be reached.1.6 RESEARCH & SURVEY OBJECTIVES1.6.1 Research ObjectivesThis study aims to describe the physical and biological characteristics in theimmediate waters that surround Misali Island. Methods and findings aresummarised from five types of subtidal surveys (benthic substrata mapping, benthicinvertebrate census, commercial fish visual census, reef-associated fish visualcensus, and systematic fish species inventory).Frontier-Tanzania Environmental Research Report 103 4
Misali Island: A detailed description of the subtidal regions1.6.2 Survey Objectives1.6.2.1 Benthic substrata mappingTo determine the types, locations and extent of subtidal habitats that surroundMisali Island. This is with the view towards...• locating areas of high biodiversity around Misali Island., relative to localand regional areas• gaining an understanding of why certain areas are more intensely fishedthan others• allowing further comparisons to be made with regards to associatedfauna found within and outside of each survey site.1.6.2.2 Benthic invertebrate censusTo commence analysis of the diversity of these organisms with respect to arepresentative list of 45 taxa.1.6.2.3 Commercial fish visual censusTo allow derivation of abundances and lengths of the main groups ofcommercially important fish and other groups such as Muraenidae (moray eels),Carcharhinidae (requiem sharks), and Dasyatidae, Myliobatidae and Mobulidae(sting, eagle and manta rays respectively).1.6.2.4 Reef-associated fish visual censusTo determine the species richness and species diversity indices of selected,representative reef fish species at each survey site.1.6.2.5 Systematic fish inventoryTo increase knowledge of the biological diversity within this region.1.7 SURVEY RATIONALE1.7.1 Benthic substrata mappingLimited research has been conducted with regards to assessment of the benthicsubstrata surrounding Misali Island (Horrill 1992, Horrill et.al. 1994, Mohammedet.al. 2000, Richmond & Mohammed 2001). Site visits since the global bleachingevent in 1998 have revealed that hard coral cover on one area to the west of MisaliIsland has decreased dramatically, from 74% (Horril et.al. 1994) to 7%(Mohammed et.al. 2000). However, survey repetition and variety of sites havebeen minimal. Therefore the degree to which this has changed over recent years,the extent, and hence the possible effects of human activities within waterssurrounding Misali, are not well understood.Studies that have been conducted around Misali have shown that the waters host acomparatively high abundance and diversity of fish, intermediate densities ofmacro-invertebrates and a reduction of macroalgae following the bleaching in 1998within Tanzania’s coastline (Horril et.al. 1994, Mohammed et.al. 2000, Richmondand Mohammed 2001). Also, the number of coral genera observed in Zanzibarduring studies undertaken in the 1990’s have almost doubled the numbersFrontier-Tanzania Environmental Research Report 103 5
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