Mangroves reduce the vulnerability of coral reef fisheries to habitat degradation.

Alice Rogers,Peter J Mumby,Steven D Gaines

doi:10.1371/journal.pbio.3000510

Alice Rogers, Peter J Mumby + Show 1 more

Open Access

https://doi.org/10.1371/journal.pbio.3000510

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Abstract

Despite general and wide-ranging negative effects of coral reef degradation on reef communities, hope might exist for reef-associated predators that use nursery habitats. When reef structural complexity is lost, refuge density declines and prey vulnerability increases. Here, we explore whether the presence of nursery habitats can promote high predator productivity on degraded reefs by mitigating the costs of increased vulnerability in early life, whilst allowing for the benefits of increased food availability in adulthood. We apply size-based ecosystem models of coral reefs with high and low structural complexity to predict fish biomass and productivity in the presence and absence of mangrove nurseries. Our scenarios allow us to elucidate the interacting effects of refuge availability and ontogenetic habitat shifts for fisheries productivity. We find that low complexity, degraded reefs with nurseries can support fisheries productivity that is equal to or greater than that in complex reefs that lack nurseries. We compare and validate model predictions with field data from Belize. Our results should inform reef fisheries management strategies and protected areas now and into the future.

Highlights

As the human population continues to grow, the food security and livelihoods of millions of people in tropical coastal communities depends on the continued productivity of coastal fisheries
While Bonaire has a small area of mangrove on its southeastern coast, it is too isolated to impact fish assemblages strongly [32], and so comparisons here are limited to scenarios lacking nursery habitats
Given that predatory species are primary targets for most coral reef fisheries and generally have a higher market value than herbivorous species, our results suggest that mangrove availability decreases the vulnerability of reef fisheries to habitat degradation and to declines in structural complexity

Summary

Introduction

As the human population continues to grow, the food security and livelihoods of millions of people in tropical coastal communities depends on the continued productivity of coastal fisheries. An important concern is that degraded reefs offer poorer habitat quality [7,8], which is expected to reduce the productivity of future reef fisheries several-fold [9,10,11]. The presence of nursery habitats, such as mangroves and seagrass beds, can enhance the biomass of multiple fish species [12,13,14,15]. They do this by offering refuge from the high predation associated with coral reefs, while providing food for rapid growth [16,17,18,19]. The mechanism by which nursery habitats influence reef fish dynamics has particular relevance in the context of reef habitat degradation

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