More coral, more fish? Contrasting snapshots from a remote Pacific atoll

Ricardo Beldade; Suzanne C Mills; Joachim Claudet; Isabelle M Côté

doi:10.7717/peerj.745

More coral, more fish? Contrasting snapshots from a remote Pacific atoll

PeerJ. 2015 Jan 29:3:e745. doi: 10.7717/peerj.745. eCollection 2015.

Authors

Ricardo Beldade¹, Suzanne C Mills², Joachim Claudet², Isabelle M Côté³

Affiliations

¹ CRIOBE, USR 3278 CNRS-EPHE-UPVD , Perpignan Cedex , France ; Laboratoire d'Excellence "CORAIL" , France ; MARE-Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa , Campo Grande, Lisboa , Portugal.
² CRIOBE, USR 3278 CNRS-EPHE-UPVD , Perpignan Cedex , France ; Laboratoire d'Excellence "CORAIL" , France.
³ Earth to Ocean Group, Department of Biological Sciences, Simon Fraser University , Burnaby, BC , Canada.

Abstract

Coral reefs are in decline across the globe as a result of overexploitation, pollution, disease and, more recently, climate change. The impacts of changes in coral cover on associated fish communities can be difficult to predict because of the uneven dependence of reef fish species on corals for food, shelter or the three-dimensional structure they provide. We compared live coral cover, reef fish community metrics, and their associations in two surveys of the lagoon of the remote atoll of Mataiva (French Polynesia) carried out 31 years apart. In contrast to the general pattern of decreasing coral cover reported for many parts of the Indo-Pacific region, live coral cover increased 6-7 fold at Mataiva between 1981 and 2012, and fish density nearly doubled. The stable overall reef fish species richness belied a significant shift in community structure. There was little overlap in community composition across years, and fish assemblages in 2012 were more homogeneous in composition than they were in 1981. Changes in species abundance were not clearly related to species-specific reliance on corals. The strong positive relationships between live coral cover and fish diversity and abundance noted in 1981, when coral cover rarely exceeded 10%, were no longer present in 2012, when coral cover rarely fell below this value. The most parsimonious explanation for these contrasting relationships is that, over the combined range of coral cover observed in the 1981 and 2012 snapshots, there is a rapidly asymptotic relationship between coral and fish. Our results, and other data from the south and west Pacific, suggest that fish diversity and abundance might accumulate rapidly up to a threshold of approximately 10% live coral cover. Such a relationship would have implications for our expectations of resistance and recovery of reef fish communities facing an increasingly severe regime of coral reef disturbances.

Keywords: Coral cover; Coral-fish relationship; Fish assemblages; Fish community structure; Functional relationship; Resilience.

Grants and funding

Funding was provided to SC Mills and J Claudet by the Agence Nationale de Recherche, ANR-11-JSV7-012-01 “Live and Let Die”, ANR-14-CE03-0001 “ACRoSS” and the LABEX CORAIL “Where do we go now?” R Beldade was funded by Fundação para a Ciência e Tecnologia (SFRH/BPD/26901/2006) and IM Côté by a Discovery grant from the National Sciences and Engineering Council of Canada. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.