Modelling dispersal and connectivity of broadcast spawning corals at the global scale

• Published in: Global ecology and biogeography Vol. 23; no. 1; pp. 1 - 11
• Main Authors: Wood, S, Paris, C. B, Ridgwell, A, Hendy, E. J
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 2014; John Wiley & Sons Ltd; Blackwell; Wiley Subscription Services, Inc
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biogeography; Biological and medical sciences; Biophysical modelling; climate change; Cnidaria. Ctenaria; connectivity; coral biogeography; Coral reefs; Coral Triangle; Corals; East Pacific Barrier; Ecological modeling; Fundamental and applied biological sciences. Psychology; General aspects; General aspects. Techniques; Geographic regions; Hawaii; Indian Ocean; Invertebrates; Larvae; larval dispersal; Marine ecology; Methods and techniques (sampling, tagging, trapping, modelling...); Ocean currents; Oceans; Reefs; Sea water ecosystems; spawning; Synecology; tropical eastern Pacific; Hawaii; Red Sea; Indian Ocean; French Polynesia; Great Barrier Reef; Polynesia; Equatorial Pacific; Pacific Ocean; East Pacific; Oceania; ISE, Pacific, Johnston Atoll; I, Indo-Pacific; ISE, Pacific, French Polynesia, Marquesas Is; ISE, USA, Hawaii; ISW, Indian Ocean; ISW, Red Sea; ISE, Chile, Easter I; ISEW, Australia, Queensland, Great Barrier Reef; I, Central Pacific; tropical eastern Pacific; Indian Ocean; Spawning; Tropical zone; larval dispersal; Biogeography; Hawaii; Coral reef; Biophysical modelling; Barrier; Ecology; Modeling; Dispersion; coral biogeography; Marine environment; Coelenterata; Larva; connectivity; coral reefs; Cnidaria; East Pacific Barrier; Invertebrata; Coral Triangle
• ISSN: 1466-822X; 1466-8238
• DOI: 10.1111/geb.12101

AIM: We develop the first global model of connectivity for a generic broadcast spawning coral, and compare the results to connectivity estimates from genetic studies, general biogeographic patterns and theories. We also derive various ‘connectivity indices’ describing relative isolation and source potential between locations. LOCATION: Modelled oceans 47° S–47° N. METHODS: Dispersal of model coral ‘larvae’ was simulated over 8 years using an individual‐based biophysical dispersal model driven by 1/12°‐resolution surface ocean current data and incorporating individual trait variability (e.g. a phased pre‐competency period). Source and arrival locations of modelled larvae on suitable reef habitat gave standardized dispersal paths and relative levels of connectivity. RESULTS: In the model c. 50% of connections occurred within 50–100 km, with rarer dispersal between regions linking entire oceans in a ‘stepping stone’ fashion. The central Pacific was an almost complete barrier to dispersal, only rarely breached westward from the Galapagos to Marquesas Islands. Areas showing strong isolation also included Hawaii, Easter Island, the Red Sea and the eastern Atlantic. The Indo‐West Pacific and Great Barrier Reef showed the highest levels of connectivity, with secondary peaks in the western Indian Ocean, corresponding to areas of enriched coral diversity. The central Indo‐Pacific diversity hotspot was overall a greater source than sink for dispersal. CONCLUSIONS: This study provides a global view of connectivity that complements genetic and biogeographic work as well as providing a number of novel findings relevant to biogeographic theories (e.g. the central Indo‐Pacific as a dispersal source; Johnston Atoll as the sole ‘stepping‐stone’ into Hawaii). Discrepancies with proposed connectivity patterns (e.g. one‐way, westward, connectivity across the central Pacific) present hypotheses for future research. The model represents an effective tool for exploring the factors controlling connectivity on this scale and the effects of climate change on future connectivity, and will also aid predictions of future reef distributions.