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Why all the algae? An assessment of the population status and distribution of key reef herbivore, Diadema antillarum, in Bacalar Chico Marine Reserve

Supervisors: Jennifer Chapman (Belize), Frances Humber / Charlotte Gough (UK)
Location: desk (data already collected)
Duration: 3-6 months

Diadema antillarum sea urchins are key reef herbivores and an outbreak of disease in 1983 resulted in mass mortality of these ecologically significant invertebrates  throughout the Caribbean (Lessios, 1988). As herbivores, the loss of this species has been linked to increases in macroalgal cover as well as an associated decrease in hard coral cover (Aronson and Precht, 2000; Idjadi et al., 2006; Lessios, 1988). The recovery of Diadema populations is of critical importance and monitored throughout the
Caribbean. Prior to the disease epidemic, populations of Diadema ranged between 4 and 25 urchins per m -2 of reef throughout the MBRS. Post-epidemic populations had dropped to less than 0.3 urchins per m -2 . Population sizes below one urchin per m 2 are considered critically low (McField and Kramer, 2007). In Bacalar Chico, Diadema were rare at synoptic reef monitoring sites (Chapman, 2012), though were opportunistically observed in large clumps elsewhere in the reserve.

The primary aim of this study is to quantitatively describe the status and distribution of Diadema in Bacalar Chico Marine Reserve, with the view to identify hotpots and/or nurseries, as well as detangle associated ecological data to determine factors limiting population recovery.

The results of this study will feed into two broader objectives:
Evaluating the effectiveness of Bacalar Chico Marine Reserve with regards to maintaining ecological health and commercial fish stock sustainability
Promoting the recovery of key reef herbivores, which play a role in preventing or reversing phase-shift change to fleshy macroalgal dominance.

Independent research projects (2013-2014) - Madagascar

Independent research projects (2013-2014) - Belize