Status of Diadema antillarum populations in Grand Anse Bay, Grenada, 30 years after mass mortality

Stephen H Nimrod; Andrea L Easter Pilcher; Karl A Aiken; Dayne St A Buddo; Chiara Franco

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Status of Diadema antillarum populations in Grand Anse Bay, Grenada, 30 years after mass mortality

Nimrod, Stephen H ^[1] ; Easter-Pilcher, Andrea L ^[2] ; Aiken, Karl A ^[1] ; Buddo, Dayne St A ^[1] ; Franco, Chiara ^[3]
1. [1] University of the West Indies
  
  University of the West Indies
  
  Jamaica
2. [2] St. George's University
  
  St. George's University
  
  Granada
3. [3] The Nature Conservancy, P.O., Kolonia, Pohnpei, Federated States of Micronesia
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Localización: Bulletin of Marine Science, ISSN 0007-4977, Vol. 93, Nº. 3, 2017, págs. 917-927
Idioma: inglés
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Resumen
- Since the mass mortality of Diadema antillarum Philippi, 1845 populations in 1983–1984, recovery has been slow and D. antillarum remain scarce at many localities across the Caribbean Sea. Yet, in 2014 we observed high densities of D. antillarum over relatively large areas of shallow nearshore coral reefs in Grand Anse Bay, Grenada. The present study sought to assess D. antillarum populations at two high-density sites in Grand Anse Bay during 2014–2015 to determine the status of D. antillarum populations on those reefs. Mean D. antillarum densities at the two sites surveyed in Grenada were relatively high [5.9 (SE 0.57) and 12.5 (SE 0.74) individuals m–2] compared with the average density (4.5 individuals m–2) of D. antillarum from a previous study in Grand Anse Bay. The majority of individuals identified at the two sites were small (9–39 mm) to medium size (40–59 mm) sea urchins. Mean density of juvenile D. antillarum (<20 mm) at site 1 was significantly greater during a nighttime survey compared with a daytime survey, suggesting that daytime surveys may have been underestimating abundance of juvenile D. antillarum on those reefs. The high density of small to medium size sea urchins, as well as the presence of several juveniles observed at night, suggests that the high D. antillarum densities found at these two sites in Grenada were unlikely to be limited by fertilization success, larval production, and/or larval survivorship.