Corals, sessile as adults, disperse by releasing a pelagic larval stage into the water, which drifts with the ocean currents over potentially thousands of kilometres between reef habitats. Determining patterns of dispersal is an important but difficult task for reef conservation science; coral larvae are impossible to track directly in the marine environment. Biophysical models provide an essential tool to explore the patterns and drivers of dispersal. However, they have previously been utilised at regional scales, excluding the potential for long-distance transport events of particular importance to coral biogeography. In light of recent computational advances, I develop the first high-resolution global model of coral larval dispersal. The model provides critical evidence regarding the influence of dispersal on coral biogeography, highlighting vulnerable isolated areas as well as important sources and stepping stones for dispersal. For example, eastern Pacific reefs emerge as some of the most isolated globally. Contrary to hypotheses of increased dispersal into this region during El Nino events, I find only westward dispersal out of the eastern Pacific over a 10 year period, including the extreme 1997-98 El Nino. The Galapagos Islands act as the sole source for dispersal across the 6000 km separating eastern from central Pacific reefs. The model is the first to incorporate the effects of environmental factors (temperature and ocean pH) on larval physiology, predicted to result in alterations to patterns of dispersal with climate change. I find that dispersal patterns are especially sensitive to the effect of temperature on larval mortality, although the response varies geographically. Increases in temperatures predicted for 2060 reduce long-distance dispersal and increase local retention in the model, potentially reducing the scale over which /management efforts will be effective. Future work will aim to incorporate various other factors likely to influence future dispersal, informing management of reefs under climate change.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:682361 |
| Date | January 2015 |
| Creators | Wood, Sally |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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