Predators drive community structure in coral reef fish assemblages

The importance of top‐down effects in structuring ecological communities has been widely debated by ecologists. One way in which to examine these processes is to study the secondary effects of predator removal on communities. This study examined the role of predatory fishes in structuring communitie...

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Main Authors: A. E. Boaden, M. .J Kingsford
Format: Article
Language:English
Published: Wiley 2015-04-01
Series:Ecosphere
Subjects:
Online Access:https://doi.org/10.1890/ES14-00292.1
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spelling doaj-822f6b9ec3e14abb8816562f1a79a3162020-11-25T02:28:16ZengWileyEcosphere2150-89252015-04-016413310.1890/ES14-00292.1Predators drive community structure in coral reef fish assemblagesA. E. Boaden0M. .J Kingsford1College of Marine and Environmental Sciences and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811 AustraliaCollege of Marine and Environmental Sciences and ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland 4811 AustraliaThe importance of top‐down effects in structuring ecological communities has been widely debated by ecologists. One way in which to examine these processes is to study the secondary effects of predator removal on communities. This study examined the role of predatory fishes in structuring communities of coral reef fishes, by using a network of marine reserves (the Great Barrier Reef Marine Park) as a natural experiment. We hypothesized that reefs with high densities of piscivores (marine reserves) would have distinct fish communities from those where piscivores have been depleted through fishing, due to variation in predation pressure. We predicted that predator depletion would result in “prey release”, and a corresponding increase in prey densities along a gradient of fishing intensity, causing a change in the community composition of reef fishes. To address this, fish counts and habitat surveys were conducted at four locations on the Great Barrier Reef. At each location, comparisons were made amongst three marine park zones that varied in their exposure to fishing practices; no‐ take marine reserves, limited fishing areas, and open fishing areas. The density and biomass of predators varied consistently among zones at each location. Furthermore, we found strong evidence for prey release at all four locations, resulting in distinct fish assemblages amongst zones. Reefs open to fishing had much lower densities of piscivores, and higher densities of prey and herbivorous fishes compared to marine reserves. This broad pattern was consistent amongst locations, and persisted at the level of species, trophic groups, families and communities. Habitat characteristics did not vary significantly amongst zones in a consistent manner amongst locations. Although habitat relationships were strong for specialist species such as butterflyfishes, densities of predators were stronger predictors of prey density for most species, and the trophic composition of reef fish communities differed significantly amongst zones at all locations. Results from this study support the concept that top‐down effects can be strong divers of prey populations and influence community structure in highly diverse systems. These data emphasize the vital role of predators, and reinforce the importance of preserving and restoring top‐down trophic interactions in ecological systems.https://doi.org/10.1890/ES14-00292.1commercial fishingconservation and managementcoral reef fisheriescoral troutfishing impactsGreat Barrier Reef
collection DOAJ
language English
format Article
sources DOAJ
author A. E. Boaden
M. .J Kingsford
spellingShingle A. E. Boaden
M. .J Kingsford
Predators drive community structure in coral reef fish assemblages
Ecosphere
commercial fishing
conservation and management
coral reef fisheries
coral trout
fishing impacts
Great Barrier Reef
author_facet A. E. Boaden
M. .J Kingsford
author_sort A. E. Boaden
title Predators drive community structure in coral reef fish assemblages
title_short Predators drive community structure in coral reef fish assemblages
title_full Predators drive community structure in coral reef fish assemblages
title_fullStr Predators drive community structure in coral reef fish assemblages
title_full_unstemmed Predators drive community structure in coral reef fish assemblages
title_sort predators drive community structure in coral reef fish assemblages
publisher Wiley
series Ecosphere
issn 2150-8925
publishDate 2015-04-01
description The importance of top‐down effects in structuring ecological communities has been widely debated by ecologists. One way in which to examine these processes is to study the secondary effects of predator removal on communities. This study examined the role of predatory fishes in structuring communities of coral reef fishes, by using a network of marine reserves (the Great Barrier Reef Marine Park) as a natural experiment. We hypothesized that reefs with high densities of piscivores (marine reserves) would have distinct fish communities from those where piscivores have been depleted through fishing, due to variation in predation pressure. We predicted that predator depletion would result in “prey release”, and a corresponding increase in prey densities along a gradient of fishing intensity, causing a change in the community composition of reef fishes. To address this, fish counts and habitat surveys were conducted at four locations on the Great Barrier Reef. At each location, comparisons were made amongst three marine park zones that varied in their exposure to fishing practices; no‐ take marine reserves, limited fishing areas, and open fishing areas. The density and biomass of predators varied consistently among zones at each location. Furthermore, we found strong evidence for prey release at all four locations, resulting in distinct fish assemblages amongst zones. Reefs open to fishing had much lower densities of piscivores, and higher densities of prey and herbivorous fishes compared to marine reserves. This broad pattern was consistent amongst locations, and persisted at the level of species, trophic groups, families and communities. Habitat characteristics did not vary significantly amongst zones in a consistent manner amongst locations. Although habitat relationships were strong for specialist species such as butterflyfishes, densities of predators were stronger predictors of prey density for most species, and the trophic composition of reef fish communities differed significantly amongst zones at all locations. Results from this study support the concept that top‐down effects can be strong divers of prey populations and influence community structure in highly diverse systems. These data emphasize the vital role of predators, and reinforce the importance of preserving and restoring top‐down trophic interactions in ecological systems.
topic commercial fishing
conservation and management
coral reef fisheries
coral trout
fishing impacts
Great Barrier Reef
url https://doi.org/10.1890/ES14-00292.1
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