Recruitment among density manipulated populations of a Caribbean gorgonian
Howard Lasker Principal Investigator
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Recruitment, the addition of new individuals to populations, has played a prominent role in analyses of the population dynamics of marine benthic species. Understanding whether recruits come from local populations (closed populations) or from distant sources (open populations) is essential to our understanding of the dynamics of benthic populations and to the conservation and management of benthic species. These questions are of particular importance for coral reef communities, which are increasingly at risk and require the development of sound conservation policies.<br/><br/>Assessing whether populations are closed or open is methodologically difficult and most such analyses have been inferential in nature. Direct and large?scale manipulations of the density of reproductive individuals could be used to experimentally test whether or not a population is open, but in most cases such manipulations are difficult to undertake due to logistical and environmental constraints. The large?scale manipulation of density of a single species is currently being generated by the harvest of the Caribbean gorgonian, Pseudopterogorgia elisabethae in the Bahamas. P. elisabethae colonies are cropped on a 2?3 y rotation and after harvest are no longer of reproductive size. This has created a mosaic of areas all of which can support the species but some of which produce dramatically reduced numbers of eggs and larvae. Examining recruitment in these areas and across a hierarchy of spatial scales, both after harvest and as the number of reproductive colonies increases, will provide a unique opportunity to directly determine whether P. elisabethae populations are closed and on what scale. Recruitment will be monitored follow annual spawning events on the Little Bahama Bank and the origin of recruits assessed from DNA microsatellite analyses of the recruits.<br/><br/>Broader Impacts<br/><br/>The broader impacts of the study are in large part based on it addressing one of the fundamental questions of marine ecology, whether marine populations are open or closed. In addition, the study focuses on a commercially important species that is currently being harvested in the Bahamas and is under investigation for harvest elsewhere in the Caribbean. The study should therefore be of broad interest to stakeholders such as governmental and nongovernmental organizations interested in the conservation and management of coral reefs.<br/><br/>Educational aspects of the project fall into two categories. Firstly, the project will involve the participation and training graduate and undergraduate students from both the U.S. and the Bahamas. Secondly, the research will form the basis for a case study to be developed for the National Center for Case Study Teaching in Science. The case study will emphasize the process by which research is developed as well as the results of the research. The case study will be used in University at Buffalo undergraduate classes and through the Center's website will be available to instructors throughout the country.