Large-Scale Experimental Test of Recruitment Limitation in Marine Fish

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This project will test the recruitment limitation hypothesis in unprecedented detail and at both large spatial scales (reefs 100's of meters in diameter) and large temporal scales (an entire generation). Preliminary work has shown that the bicolor damselfish (Stegastes partitus, Pomacentridae), having a generation time of about 3 years, is a superb species for this test, and that the Caribbean Marine Research Center at Lee Stocking Island, Bahamas, is an ideal study area. The recruitment limitation hypothesis will be tested in two ways: (1) by long-term monitoring of demographic rates at four large reefs that naturally undergo vastly different rates of larval settlement, and (2) by experimental manipulations of rates of larval settlement to these sites. Sites with low settlement-either natural or experimentally induced-should corroborate the hypothesis, as suggested by baseline demographic monitoring over the past 2 years. Detailed demographic data will be used to construct empirically based size-structured open-population models. Elasticity analysis of these models will determine the relative importance of different demographic rates in driving changes in local population size.The combined observational-experimental and empirical-theoretical approach of this study will provide a novel large-scale test of the recruitment limitation hypothesis for marine fish. Additionally, this project may provide insight on the effects of human-induced global climate change on coral reefs. Baseline demographic monitoring has detected a region-wide 3-year decline in bicolor damselfish populations correlated with the bleaching and death of the corals they inhabit. This project will determine whether this population decline is a long-term, multi-generation trend.