Coral decline threatens fish biodiversity in marine reserves

Abstract

The worldwide decline in coral cover has serious implications for the health of coral reefs. But what is the future of reef fish assemblages? Marine reserves can protect fish from exploitation, but do they protect fish biodiversity in degrading environments? The answer appears to be no, as indicated by our 8-year study in Papua New Guinea. A devastating decline in coral cover caused a parallel decline in fish biodiversity, both in marine reserves and in areas open to fishing. Over 75% of reef fish species declined in abundance, and 50% declined to less than half of their original numbers. The greater the dependence species have on living coral as juvenile recruitment sites, the greater the observed decline in abundance. Several rare coral-specialists became locally extinct. We suggest that fish biodiversity is threatened wherever permanent reef degradation occurs and warn that marine reserves will not always be sufficient to ensure their survival.M any ecologists have expressed concern over the worldwide decline in coral cover due to global warming and associated coral bleaching, overfishing, and coastal pollution (1-5). Coral reefs support a high diversity of fishes that may ultimately depend on corals for their survival; however, the impact of long-term reef degradation on fish populations is unknown. Most attention to the protection of marine fish populations has focused on the benefits of controlling exploitation by establishing ''no-take'' marine reserves (6-8). However, comprehensive strategies for protecting marine biodiversity also require an understanding of how species respond to degradation of their habitats.In the past, there has been a dichotomy of opinion over how closely fish communities are linked to their habitat, with some information indicating a high degree of variability that is independent of habitat change (9-14) and other data showing that coral-specialists clearly suffer when coral cover is reduced (13-17). Here we ask the following questions. If coral reefs continue along a path of degradation, what will be the fate of fish communities as a whole? Will marine reserves provide fish communities with any resilience to the effects of habitat loss? MethodsIn 1996, we observed the beginning of what progressed into a long-term decline in coral cover in four marine reserves in the Tamane Puli Conservation Area, Kimbe Bay, Papua New Guinea (150°06ЈE, 5°25ЈS). To predict the potential response of fish assemblages to declining coral in this area, we began by estimating the proportion of reef fish species that only fed on coral tissue or those that only lived in association with branching corals. We surveyed all species in 20 different families of fishes associated with coral reefs in the region (18). Those species dependent on live coral as food or living space were distinguished from the rest, based both on our own observations and published accounts of diet and habitat associations (19,20).The cover of branching scleractinian corals was estimated from annual surveys of eight reefs between 1996 a...

Fifty million years of herbivory on coral reefs: fossils, fish and functional innovations

“…On modern coral reefs, these surfaces are exploited by a wide range of surgeonfish species and it is likely that feeding on this surface gave rise to the highly modified modern detritus-feeding specialists (traditionally placed in the genus Ctenochaetus). Today, a single lineage (Acanthurus inc. Ctenochaetus) dominates herbivory on coral reefs both numerically and in terms of species richness [55][56][57][58]. The observed changes in surgeonfish morphology and inferred abilities strongly support a proposed two-phase development of coral reef ecosystems, with the first wave in the Eocene and the second wave of highly specialized forms arising in the Oligocene or Miocene [8,9,20].…”

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“…We have previously established that a significant proportion of juveniles recruit to natal reefs for populations of both species at Kimbe Island, Papua New Guinea (PNG) 18,22 , but bidirectional movement patterns of larvae across the Kimbe Bay seascape remain unknown. Effective conservation strategies are vital, as members of both fish families are targeted by the aquarium fish trade 28 and are susceptible to local extirpation as a result of habitat degradation caused by the development of coastal land 29 . An understanding of larval connectivity is critical to ensure that reserve networks are designed to maximize the probability of population persistence in the face of rapid environmental changes 18 .…”

Suitability Analysis For Scuba Diving To Develop Marine Tourism At Saebus Island, East Java, Indonesia

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