Reef-fish larval dispersal patterns validate no-take marine reserve network connectivity that links human communities
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Networks of no-take marine reserves (NTMRs) are a widely advocated strategy for managing coral reefs. However, uncertainty about the strength of population connectivity between individual reefs and NTMRs through larval dispersal remains a major obstacle to effective network design. In this study, larval dispersal among NTMRs and fishing grounds in the Philippines was inferred by conducting genetic parentage analysis on a coral-reef fish (Chaetodon vagabundus). Adult and juvenile fish were sampled intensively in an area encompassing approximately 90 km of coastline. Thirty-seven true parent-offspring pairs were accepted after screening 1978 juveniles against 1387 adults. The data showed all types of dispersal connections that may occur in NTMR networks, with assignments suggesting connectivity among NTMRs and fishing grounds (n = 35) far outnumbering those indicating self-recruitment (n = 2). Critically, half (51%) of the inferred occurrences of larval dispersal linked reefs managed by separate, independent municipalities and constituent villages, emphasising the need for nested collaborative management arrangements across management units to sustain NTMR networks. Larval dispersal appeared to be influenced by wind-driven seasonal reversals in the direction of surface currents. The best-fit larval dispersal kernel estimated from the parentage data predicted that 50% of larvae originating from a population would attempt to settle within 33 km, and 95% within 83 km. Mean larval dispersal distance was estimated to be 36.5 km. These results suggest that creating a network of closely spaced (less than a few tens of km apart) NTMRs can enhance recruitment for protected and fished populations throughout the NTMR network. The findings underscore major challenges for regional coral-reef management initiatives that must be addressed with priority: (1) strengthening management of NTMR networks across political or customary boundaries; and (2) achieving adequate population connectivity via larval dispersal to sustain reef-fish populations within these networks.
KeywordsCommunity fisheries Coral Triangle Marine protected areas Network persistence Recruitment subsidy
Financial support was provided by the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) ACCCoast Program to RAA, the ARC Centre of Excellence for Coral Reef Studies at JCU to GRR and KAUST baseline research funds to MLB. Collection of samples was permitted by the Department of Agriculture-Bureau of Fisheries and Aquatic Resources (DA-BFAR) in accordance with Philippine laws and regulations (RA 9147; FAO 233) and approved by the JCU animal ethics committee. Prior informed consent and support for this research was given by fisherfolk communities and municipal officials in Negros and the AIPLS Protected Area Management Board. ENRD-Negros Oriental, M. Teves, M. Barillo, D. Inocencio, R. Tuble, T. Yucor, R. Tubat, M. Pascobello, S. Leahy, A. Bucol, A. Regalado, O. Paderanga, M. Martin, J. Maypa and SU-IEMS provided valuable assistance. G. Almany, H. Harrison, G. Jones and S. Planes are thanked for their support. A. Bucol and D. C. Lou processed the otoliths. Staff at the KAUST Bioscience Core Laboratory assisted with DNA analysis. The authors are grateful to two anonymous reviewers whose comments greatly improved the paper. RAA dedicates this work to the memory of E. Q. Abesamis.
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