Determining how ecosystem function and services are related to diversity is necessary for predict... more Determining how ecosystem function and services are related to diversity is necessary for predicting the consequences of diversity loss and for setting goals and priorities for marine conservation. The consequences of biodiversity loss for ecosystem functions and services depend on the level of functional redundancy – the number of species with similar ecological functional traits. Using field data on fish assemblages from 199 coral reef and lagoon sites from six islands, and on local fisheries from four islands in The Bahamas, we examined levels of functional diversity and redundancy within these assemblages and determined how fish biomass and local fisheries catches vary with local diversity. A majority of functional groups contain few species, suggesting that these assemblages have limited functional redundancy. Most also include species targeted by local fisheries, thus fishing has the potential to broadly impact food webs. Comparisons between a large marine reserve and fished reefs confirm that fishing significantly reduces functional redundancy and removes whole functional groups. Positive exponential relationships of fish biomass and fisheries catches with species and functional diversity highlight that even small declines in biodiversity may result in large reductions in secondary production and seafood provision. Taken together, these results indicate that Caribbean fish assemblages have low functional redundancy and high vulnerability of ecosystem functions and services to diversity loss, and that protection of multi-species assemblages is needed to maintain functions and services.
Foraging grounds are critical to the survival of marine turtles, yet studies of these areas lag b... more Foraging grounds are critical to the survival of marine turtles, yet studies of these areas lag behind those of nesting sites. Our study represents the first data and discussion on marine turtle distribution, abundance, and health at a marine turtle foraging ground in the central Pacific, Palmyra Atoll National Wildlife Refuge, which constitutes a regionally important mixed-size-class foraging ground for green turtles (Chelonia mydas) and, to a lesser extent, for hawksbill turtles (Eretmochelys imbricata). Surveys and anecdotal reports suggest that nesting activity is rare, and we have confirmed the presence of limited suitable nesting habitat. During in-water activities from 2008 to 2011, we caught 211 green turtles ranging from postpelagic juveniles to adults (weight: mean = 44.6 kg, range = 7.2–146.3 kg; curved carapace length (CCL): mean = 69.7 cm, range = 41.0–113.6 cm) and 2 juvenile hawksbills (weight2009 = 16.3 kg, CCL2009 = 57.0; weight2011 = 11.2 kg, CCL2011 = 50.5 cm). Body condition indices did not significantly differ by year of capture. These indices, along with the absence of observed fibropapilloma tumors, indicated that turtles at Palmyra Atoll were on average in very good condition. We also conducted 11 relative abundance surveys from 2005 to 2011, a subset of which revealed an uneven distribution of turtles around Palmyra Atoll with 3 hot spots of turtle abundance off the flats to the north, south, and east. By linking several aspects of our research program with similar efforts at foraging grounds throughout the Pacific Basin, we can further our understanding of poorly known regional migratory connectivity.
Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012, 2012
With the ongoing transition between the barter and the cash economy in Papua New Guinea (PNG), tr... more With the ongoing transition between the barter and the cash economy in Papua New Guinea (PNG), traditional resource production and exploitation must adapt to the changing markets. The increasing demands for goods and services have resulted in coastal and marine resources in PNG showing signs of overexploitation. Andra Island in Manus Province is one of many islands whose inhabitants are highly dependent on the sea for sustenance and livelihoods. Ecological studies by the Wildlife Conservation Society have revealed that the surrounding reefs are denuded of branching Acropora corals compared with similar sites in Manus and elsewhere. This is likely to be due to the island’s economic dependence on the harvest of Acropora corals for the coral lime trade. Lime (calcium hydroxide) is chewed with betelnut (Areca catechu) throughout most coastal regions of PNG, and Andra has a monopoly on the lime trade in Manus. A coral farming project was implemented with the aim of providing a sustainable means of maintaining the coral lime trade. Unlike other coral farming projects in the Pacific, this project operates completely at the local scale and is not reliant on overseas markets; nor does it face the logistical challenges of the aquarium trade. We assess here the degree to which the coral farming activities contribute to livelihoods while relieving extractive pressure on reefs. The project has potential to expand throughout other regions of PNG where corals are harvested for lime.
To investigate population differentiation in a comparative and historical context, segments of th... more To investigate population differentiation in a comparative and historical context, segments of the mitochondrial cytochrome c oxidase subunit I gene and the control region were sequenced in Panulirus argus from nine sites along approximately 1,500 km of the Northern Caribbean Sea (n = 326) and analyzed with respect to available panulirid data. A mismatch analysis and Fu’s F S test uncovered a signature of historical population expansion around the time of the Last Glacial Maximum. Significant population structure was not detected in the area. The data supported a hypothesis of panmixia resulting from ongoing larval transport by ocean currents and historical population expansion. Despite high intraspecific divergence levels at COI within Panulirus argus and several other Panulirus species, genetic species identification through DNA barcoding was feasible using either a modified distance threshold or a character-based approach.
Large animals are severely depleted in many ecosystems, yet we are only beginning to understand t... more Large animals are severely depleted in many ecosystems, yet we are only beginning to understand the ecological implications of their loss. To empirically measure the short-term effects of removing large animals from an ocean ecosystem, we used exclosures to remove large fish from a near-pristine coral reef at Palmyra Atoll, Central Pacific Ocean. We identified a range of effects that followed from the removal of these large fish. These effects were revealed within weeks of their removal. Removing large fish (1) altered the behavior of prey fish; (2) reduced rates of herbivory on certain species of reef algae; (3) had both direct positive (reduced mortality of coral recruits) and indirect negative (through reduced grazing pressure on competitive algae) impacts on recruiting corals; and (4) tended to decrease abundances of small mobile benthic invertebrates. Results of this kind help advance our understanding of the ecological importance of large animals in ecosystems.
No-take reserves are a common tool for fisheries management and biodiversity conservation in mari... more No-take reserves are a common tool for fisheries management and biodiversity conservation in marine ecosystems. Despite much discussion of their benefits, data documenting many reserve effects are surprisingly scarce. Several studies have also been criticized for a lack of rigour so that changes within reserves cannot be separated from underlying natural variation and attributed unequivocally to protection. We sampled both benthic (video quadrats) and associated fish communities (underwater visual censuses) in a well-enforced reserve in The Bahamas. Sampling was explicitly stratified by habitat (‘Montastraea reef’ and ‘gorgonian plain’). To distinguish reserve effects from natural variation, we compared changes inside and outside the reserve with those seen at equivalent spatial scales in other reef systems in the Bahamian archipelago that lack reserves. Reserve-level differences in benthic or fish communities not documented in other reef systems are categorized as ‘robust’ effects.3Robust reserve effects were limited to Montastraea reefs. The reserve supported an average of 15% more fish species per site compared to outside the reserve. This pattern was particularly driven by more large-bodied grouper, damselfish, and butterflyfish species inside the reserve. Increases in fish biomass and differences in community structure inside the reserve were limited to large-bodied groupers. Increased grazing pressure by parrotfishes in the reserve has lowered macroalgal cover, and caused previously undocumented changes in benthic community structure compared to sites outside the reserve.4Some reserve-level differences in fish communities were categorized as ‘misleading’ because equivalent differences were seen in other reef systems, and are likely to be caused by natural intra-habitat variation. Separation of robust and misleading results was only possible because of archipelago-scale sampling.5Synthesis and applications. The Bahamas represents a relatively lightly fished system within the Caribbean. However, cessation of fishing has still increased the mean number of species, the abundance of the most highly prized fishes and, through trophic cascades, altered benthic community structure. In certain habitats, reserves are clearly important for conserving fisheries and biodiversity. However, reserve effects must be explicitly separated from confounding variables to ensure conservation benefits are accurately identified and reported, and not oversold to managers and local stakeholders.No-take reserves are a common tool for fisheries management and biodiversity conservation in marine ecosystems. Despite much discussion of their benefits, data documenting many reserve effects are surprisingly scarce. Several studies have also been criticized for a lack of rigour so that changes within reserves cannot be separated from underlying natural variation and attributed unequivocally to protection.We sampled both benthic (video quadrats) and associated fish communities (underwater visual censuses) in a well-enforced reserve in The Bahamas. Sampling was explicitly stratified by habitat (‘Montastraea reef’ and ‘gorgonian plain’). To distinguish reserve effects from natural variation, we compared changes inside and outside the reserve with those seen at equivalent spatial scales in other reef systems in the Bahamian archipelago that lack reserves. Reserve-level differences in benthic or fish communities not documented in other reef systems are categorized as ‘robust’ effects.Robust reserve effects were limited to Montastraea reefs. The reserve supported an average of ª 15% more fish species per site compared to outside the reserve. This pattern was particularly driven by more large-bodied grouper, damselfish, and butterflyfish species inside the reserve. Increases in fish biomass and differences in community structure inside the reserve were limited to large-bodied groupers. Increased grazing pressure by parrotfishes in the reserve has lowered macroalgal cover, and caused previously undocumented changes in benthic community structure compared to sites outside the reserve.Some reserve-level differences in fish communities were categorized as ‘misleading’ because equivalent differences were seen in other reef systems, and are likely to be caused by natural intra-habitat variation. Separation of robust and misleading results was only possible because of archipelago-scale sampling.Synthesis and applications. The Bahamas represents a relatively lightly fished system within the Caribbean. However, cessation of fishing has still increased the mean number of species, the abundance of the most highly prized fishes and, through trophic cascades, altered benthic community structure. In certain habitats, reserves are clearly important for conserving fisheries and biodiversity. However, reserve effects must be explicitly separated from confounding variables to ensure conservation benefits are accurately identified and reported, and not oversold to managers and local stakeholders.
Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve n... more Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve networks are designed, but their efficacy as surrogates for species richness and applicability to other conservation measures is poorly understood. Combining an analysis of field survey data, literature review, and expert assessment by a multidisciplinary working group, we examined the degree to which Caribbean coastal habitats provide useful planning information on 4 conservation measures: species richness, the ecological functions of fish species, ecosystem processes, and ecosystem services. Approximately one-quarter to one-third of benthic invertebrate species and fish species (disaggregated by life phase; hereafter fish species) occurred in a single habitat, and Montastraea-dominated forereefs consistently had the highest richness of all species, processes, and services. All 11 habitats were needed to represent all 277 fish species in the seascape, although reducing the conservation target to 95% of species approximately halved the number of habitats required to ensure representation. Species accumulation indices (SAIs) were used to compare the efficacy of surrogates and revealed that fish species were a more appropriate surrogate of benthic species (SAI = 71%) than benthic species were for fishes (SAI = 42%). Species of reef fishes were also distributed more widely across the seascape than invertebrates and therefore their use as a surrogate simultaneously included mangroves, sea grass, and coral reef habitats. Functional classes of fishes served as effective surrogates of fish and benthic species which, given their ease to survey, makes them a particularly useful measure for conservation planning. Ecosystem processes and services exhibited great redundancy among habitats and were ineffective as surrogates of species. Therefore, processes and services in this case were generally unsuitable for a complementarity-based approach to reserve design. In contrast, the representation of species or functional classes ensured inclusion of all processes and services in the reserve network.Resumen: Los mapas de hábitat a menudo son el núcleo de datos espacialmente consistentes sobre el cual se diseñan las redes de reservas marinas, pero su eficacia como sustitutos de la riqueza de especies y su aplicabilidad en otras medidas de conservación es poco conocida. Combinando el análisis de datos de campo, revisión de literatura y evaluación de expertos de un grupo de trabajo multidisciplinario, examinamos el grado en que los hábitats Caribeños proporcionan información útil para la planificación sobre 4 medidas de conservación: riqueza de especies, las funciones ecológicas de especies de peces, los procesos del ecosistema y los servicios del ecosistema. Aproximadamente entre una cuarta parte y un tercio de las especies de invertebrados bentónicos y de peces (desagregados por etapa de vida; en lo sucesivo especies de peces) ocurrieron en un solo hábitat, y la parte anterior de los arrecifes dominada por Montastraea consistentemente presentó la mayor riqueza de todas las especies, procesos y servicios. Los 11 hábitats fueron necesarios para representar a las 277 especies de peces en el paisaje marino, aunque al reducir el objetivo de conservación a 95% de las especies se requería aproximadamente la mitad de los hábitats para asegurar la representación. Los índices de acumulación de especies (IAE) fueron utilizados para comparar la eficacia de sustitutos y reveló que las especies de peces eran un sustituto más adecuado de las especies bentónicas (IAE = 71%) que las especies bentónicas fueron para los peces (IAE = 42%). Las especies de peces de arrecifes también se distribuyeron más ampliamente que los invertebrados y, por lo tanto, su uso como sustitutos simultáneamente incluyó hábitats en manglares, pastos marinos y arrecifes de coral. Las clases funcionales de peces sirvieron como sustitutos efectivos de especies de peces y bentónicas, lo cual, por la facilidad con que son muestreadas, las hace una medida particularmente útil para la planificación de la conservación. Los procesos y servicios del ecosistema exhibieron gran redundancia entre hábitats y fueron ineficientes como sustitutos de especies. Por lo tanto, los procesos y servicios en este caso fueron inadecuados para un método de diseño de reservas basado en complementariedad. En contraste, la representación de especies o clases funcionales aseguró la inclusión de todos los procesos y servicios en la red de reservas.Resumen: Los mapas de hábitat a menudo son el núcleo de datos espacialmente consistentes sobre el cual se diseñan las redes de reservas marinas, pero su eficacia como sustitutos de la riqueza de especies y su aplicabilidad en otras medidas de conservación es poco conocida. Combinando el análisis de datos de campo, revisión de literatura y evaluación de expertos de un grupo de trabajo multidisciplinario, examinamos el grado en que los hábitats Caribeños proporcionan información útil para la planificación sobre 4 medidas de conservación: riqueza de especies, las funciones ecológicas de especies de peces, los procesos del ecosistema y los servicios del ecosistema. Aproximadamente entre una cuarta parte y un tercio de las especies de invertebrados bentónicos y de peces (desagregados por etapa de vida; en lo sucesivo especies de peces) ocurrieron en un solo hábitat, y la parte anterior de los arrecifes dominada por Montastraea consistentemente presentó la mayor riqueza de todas las especies, procesos y servicios. Los 11 hábitats fueron necesarios para representar a las 277 especies de peces en el paisaje marino, aunque al reducir el objetivo de conservación a 95% de las especies se requería aproximadamente la mitad de los hábitats para asegurar la representación. Los índices de acumulación de especies (IAE) fueron utilizados para comparar la eficacia de sustitutos y reveló que las especies de peces eran un sustituto más adecuado de las especies bentónicas (IAE = 71%) que las especies bentónicas fueron para los peces (IAE = 42%). Las especies de peces de arrecifes también se distribuyeron más ampliamente que los invertebrados y, por lo tanto, su uso como sustitutos simultáneamente incluyó hábitats en manglares, pastos marinos y arrecifes de coral. Las clases funcionales de peces sirvieron como sustitutos efectivos de especies de peces y bentónicas, lo cual, por la facilidad con que son muestreadas, las hace una medida particularmente útil para la planificación de la conservación. Los procesos y servicios del ecosistema exhibieron gran redundancia entre hábitats y fueron ineficientes como sustitutos de especies. Por lo tanto, los procesos y servicios en este caso fueron inadecuados para un método de diseño de reservas basado en complementariedad. En contraste, la representación de especies o clases funcionales aseguró la inclusión de todos los procesos y servicios en la red de reservas.
Since the mass mortality of the urchin Diadema antillarum in 1983, parrotfishes have become the d... more Since the mass mortality of the urchin Diadema antillarum in 1983, parrotfishes have become the dominant grazer on Caribbean reefs. The grazing capacity of these fishes could be impaired if marine reserves achieve their long-term goal of restoring large consumers, several of which prey on parrotfishes. Here we compare the negative impacts of enhanced predation with the positive impacts of reduced fishing mortality on parrotfishes inside reserves. Because large-bodied parrotfishes escape the risk of predation from a large piscivore (the Nassau grouper), the predation effect reduced grazing by only 4 to 8%. This impact was overwhelmed by the increase in density of large parrotfishes, resulting in a net doubling of grazing. Increased grazing caused a fourfold reduction in the cover of macroalgae, which, because they are the principal competitors of corals, highlights the potential importance of reserves for coral reef resilience.
Abstract. Pieces of coral rubble (Porites porites), collected from across 3 fringing reefs that l... more Abstract. Pieces of coral rubble (Porites porites), collected from across 3 fringing reefs that lie along a eutrophication gradient, were examined for the presence of clionid sponges. A similarity analysis of species composition showed that reef zone had less effect on clionid community composition than did other factors affecting the reefs as a whole. Except on the back reef, the Zones, distances, and depths within the reefs had no significant influence on the number of clionid invasions. Reef comparisons demonstrated that clionid abundance increased with increasing eutrophication. Clionids were found in 41% of the pieces collected from the most eutrophic site vs. 24% from the least eutrophic. Because clionids are the principal bio-eroders of coral reefs, any increase in their abundance will likely result in greater bioerosion rates. The mean abundance of Type 3 corals (in which fragmentation is the primary mode of propagation) is positively related to the frequency of boring sponge invasion. suggesting that increased bioerosion may be partly responsible for community shifts toward Type 3 corals in polluted waters. Cliona cf. vastifica, found for the first time in Barbados, flourishes on the most eutrophic reef and may become an important bioeroder under the highly eutrophic conditions that have begun to plague West Indian reefs. Two new species of Cliona (Porifera: Hadro-merida: Clionidae) are described.
Determining how ecosystem function and services are related to diversity is necessary for predict... more Determining how ecosystem function and services are related to diversity is necessary for predicting the consequences of diversity loss and for setting goals and priorities for marine conservation. The consequences of biodiversity loss for ecosystem functions and services depend on the level of functional redundancy – the number of species with similar ecological functional traits. Using field data on fish assemblages from 199 coral reef and lagoon sites from six islands, and on local fisheries from four islands in The Bahamas, we examined levels of functional diversity and redundancy within these assemblages and determined how fish biomass and local fisheries catches vary with local diversity. A majority of functional groups contain few species, suggesting that these assemblages have limited functional redundancy. Most also include species targeted by local fisheries, thus fishing has the potential to broadly impact food webs. Comparisons between a large marine reserve and fished reefs confirm that fishing significantly reduces functional redundancy and removes whole functional groups. Positive exponential relationships of fish biomass and fisheries catches with species and functional diversity highlight that even small declines in biodiversity may result in large reductions in secondary production and seafood provision. Taken together, these results indicate that Caribbean fish assemblages have low functional redundancy and high vulnerability of ecosystem functions and services to diversity loss, and that protection of multi-species assemblages is needed to maintain functions and services.
Foraging grounds are critical to the survival of marine turtles, yet studies of these areas lag b... more Foraging grounds are critical to the survival of marine turtles, yet studies of these areas lag behind those of nesting sites. Our study represents the first data and discussion on marine turtle distribution, abundance, and health at a marine turtle foraging ground in the central Pacific, Palmyra Atoll National Wildlife Refuge, which constitutes a regionally important mixed-size-class foraging ground for green turtles (Chelonia mydas) and, to a lesser extent, for hawksbill turtles (Eretmochelys imbricata). Surveys and anecdotal reports suggest that nesting activity is rare, and we have confirmed the presence of limited suitable nesting habitat. During in-water activities from 2008 to 2011, we caught 211 green turtles ranging from postpelagic juveniles to adults (weight: mean = 44.6 kg, range = 7.2–146.3 kg; curved carapace length (CCL): mean = 69.7 cm, range = 41.0–113.6 cm) and 2 juvenile hawksbills (weight2009 = 16.3 kg, CCL2009 = 57.0; weight2011 = 11.2 kg, CCL2011 = 50.5 cm). Body condition indices did not significantly differ by year of capture. These indices, along with the absence of observed fibropapilloma tumors, indicated that turtles at Palmyra Atoll were on average in very good condition. We also conducted 11 relative abundance surveys from 2005 to 2011, a subset of which revealed an uneven distribution of turtles around Palmyra Atoll with 3 hot spots of turtle abundance off the flats to the north, south, and east. By linking several aspects of our research program with similar efforts at foraging grounds throughout the Pacific Basin, we can further our understanding of poorly known regional migratory connectivity.
Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012, 2012
With the ongoing transition between the barter and the cash economy in Papua New Guinea (PNG), tr... more With the ongoing transition between the barter and the cash economy in Papua New Guinea (PNG), traditional resource production and exploitation must adapt to the changing markets. The increasing demands for goods and services have resulted in coastal and marine resources in PNG showing signs of overexploitation. Andra Island in Manus Province is one of many islands whose inhabitants are highly dependent on the sea for sustenance and livelihoods. Ecological studies by the Wildlife Conservation Society have revealed that the surrounding reefs are denuded of branching Acropora corals compared with similar sites in Manus and elsewhere. This is likely to be due to the island’s economic dependence on the harvest of Acropora corals for the coral lime trade. Lime (calcium hydroxide) is chewed with betelnut (Areca catechu) throughout most coastal regions of PNG, and Andra has a monopoly on the lime trade in Manus. A coral farming project was implemented with the aim of providing a sustainable means of maintaining the coral lime trade. Unlike other coral farming projects in the Pacific, this project operates completely at the local scale and is not reliant on overseas markets; nor does it face the logistical challenges of the aquarium trade. We assess here the degree to which the coral farming activities contribute to livelihoods while relieving extractive pressure on reefs. The project has potential to expand throughout other regions of PNG where corals are harvested for lime.
To investigate population differentiation in a comparative and historical context, segments of th... more To investigate population differentiation in a comparative and historical context, segments of the mitochondrial cytochrome c oxidase subunit I gene and the control region were sequenced in Panulirus argus from nine sites along approximately 1,500 km of the Northern Caribbean Sea (n = 326) and analyzed with respect to available panulirid data. A mismatch analysis and Fu’s F S test uncovered a signature of historical population expansion around the time of the Last Glacial Maximum. Significant population structure was not detected in the area. The data supported a hypothesis of panmixia resulting from ongoing larval transport by ocean currents and historical population expansion. Despite high intraspecific divergence levels at COI within Panulirus argus and several other Panulirus species, genetic species identification through DNA barcoding was feasible using either a modified distance threshold or a character-based approach.
Large animals are severely depleted in many ecosystems, yet we are only beginning to understand t... more Large animals are severely depleted in many ecosystems, yet we are only beginning to understand the ecological implications of their loss. To empirically measure the short-term effects of removing large animals from an ocean ecosystem, we used exclosures to remove large fish from a near-pristine coral reef at Palmyra Atoll, Central Pacific Ocean. We identified a range of effects that followed from the removal of these large fish. These effects were revealed within weeks of their removal. Removing large fish (1) altered the behavior of prey fish; (2) reduced rates of herbivory on certain species of reef algae; (3) had both direct positive (reduced mortality of coral recruits) and indirect negative (through reduced grazing pressure on competitive algae) impacts on recruiting corals; and (4) tended to decrease abundances of small mobile benthic invertebrates. Results of this kind help advance our understanding of the ecological importance of large animals in ecosystems.
No-take reserves are a common tool for fisheries management and biodiversity conservation in mari... more No-take reserves are a common tool for fisheries management and biodiversity conservation in marine ecosystems. Despite much discussion of their benefits, data documenting many reserve effects are surprisingly scarce. Several studies have also been criticized for a lack of rigour so that changes within reserves cannot be separated from underlying natural variation and attributed unequivocally to protection. We sampled both benthic (video quadrats) and associated fish communities (underwater visual censuses) in a well-enforced reserve in The Bahamas. Sampling was explicitly stratified by habitat (‘Montastraea reef’ and ‘gorgonian plain’). To distinguish reserve effects from natural variation, we compared changes inside and outside the reserve with those seen at equivalent spatial scales in other reef systems in the Bahamian archipelago that lack reserves. Reserve-level differences in benthic or fish communities not documented in other reef systems are categorized as ‘robust’ effects.3Robust reserve effects were limited to Montastraea reefs. The reserve supported an average of 15% more fish species per site compared to outside the reserve. This pattern was particularly driven by more large-bodied grouper, damselfish, and butterflyfish species inside the reserve. Increases in fish biomass and differences in community structure inside the reserve were limited to large-bodied groupers. Increased grazing pressure by parrotfishes in the reserve has lowered macroalgal cover, and caused previously undocumented changes in benthic community structure compared to sites outside the reserve.4Some reserve-level differences in fish communities were categorized as ‘misleading’ because equivalent differences were seen in other reef systems, and are likely to be caused by natural intra-habitat variation. Separation of robust and misleading results was only possible because of archipelago-scale sampling.5Synthesis and applications. The Bahamas represents a relatively lightly fished system within the Caribbean. However, cessation of fishing has still increased the mean number of species, the abundance of the most highly prized fishes and, through trophic cascades, altered benthic community structure. In certain habitats, reserves are clearly important for conserving fisheries and biodiversity. However, reserve effects must be explicitly separated from confounding variables to ensure conservation benefits are accurately identified and reported, and not oversold to managers and local stakeholders.No-take reserves are a common tool for fisheries management and biodiversity conservation in marine ecosystems. Despite much discussion of their benefits, data documenting many reserve effects are surprisingly scarce. Several studies have also been criticized for a lack of rigour so that changes within reserves cannot be separated from underlying natural variation and attributed unequivocally to protection.We sampled both benthic (video quadrats) and associated fish communities (underwater visual censuses) in a well-enforced reserve in The Bahamas. Sampling was explicitly stratified by habitat (‘Montastraea reef’ and ‘gorgonian plain’). To distinguish reserve effects from natural variation, we compared changes inside and outside the reserve with those seen at equivalent spatial scales in other reef systems in the Bahamian archipelago that lack reserves. Reserve-level differences in benthic or fish communities not documented in other reef systems are categorized as ‘robust’ effects.Robust reserve effects were limited to Montastraea reefs. The reserve supported an average of ª 15% more fish species per site compared to outside the reserve. This pattern was particularly driven by more large-bodied grouper, damselfish, and butterflyfish species inside the reserve. Increases in fish biomass and differences in community structure inside the reserve were limited to large-bodied groupers. Increased grazing pressure by parrotfishes in the reserve has lowered macroalgal cover, and caused previously undocumented changes in benthic community structure compared to sites outside the reserve.Some reserve-level differences in fish communities were categorized as ‘misleading’ because equivalent differences were seen in other reef systems, and are likely to be caused by natural intra-habitat variation. Separation of robust and misleading results was only possible because of archipelago-scale sampling.Synthesis and applications. The Bahamas represents a relatively lightly fished system within the Caribbean. However, cessation of fishing has still increased the mean number of species, the abundance of the most highly prized fishes and, through trophic cascades, altered benthic community structure. In certain habitats, reserves are clearly important for conserving fisheries and biodiversity. However, reserve effects must be explicitly separated from confounding variables to ensure conservation benefits are accurately identified and reported, and not oversold to managers and local stakeholders.
Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve n... more Abstract: Habitat maps are often the core spatially consistent data set on which marine reserve networks are designed, but their efficacy as surrogates for species richness and applicability to other conservation measures is poorly understood. Combining an analysis of field survey data, literature review, and expert assessment by a multidisciplinary working group, we examined the degree to which Caribbean coastal habitats provide useful planning information on 4 conservation measures: species richness, the ecological functions of fish species, ecosystem processes, and ecosystem services. Approximately one-quarter to one-third of benthic invertebrate species and fish species (disaggregated by life phase; hereafter fish species) occurred in a single habitat, and Montastraea-dominated forereefs consistently had the highest richness of all species, processes, and services. All 11 habitats were needed to represent all 277 fish species in the seascape, although reducing the conservation target to 95% of species approximately halved the number of habitats required to ensure representation. Species accumulation indices (SAIs) were used to compare the efficacy of surrogates and revealed that fish species were a more appropriate surrogate of benthic species (SAI = 71%) than benthic species were for fishes (SAI = 42%). Species of reef fishes were also distributed more widely across the seascape than invertebrates and therefore their use as a surrogate simultaneously included mangroves, sea grass, and coral reef habitats. Functional classes of fishes served as effective surrogates of fish and benthic species which, given their ease to survey, makes them a particularly useful measure for conservation planning. Ecosystem processes and services exhibited great redundancy among habitats and were ineffective as surrogates of species. Therefore, processes and services in this case were generally unsuitable for a complementarity-based approach to reserve design. In contrast, the representation of species or functional classes ensured inclusion of all processes and services in the reserve network.Resumen: Los mapas de hábitat a menudo son el núcleo de datos espacialmente consistentes sobre el cual se diseñan las redes de reservas marinas, pero su eficacia como sustitutos de la riqueza de especies y su aplicabilidad en otras medidas de conservación es poco conocida. Combinando el análisis de datos de campo, revisión de literatura y evaluación de expertos de un grupo de trabajo multidisciplinario, examinamos el grado en que los hábitats Caribeños proporcionan información útil para la planificación sobre 4 medidas de conservación: riqueza de especies, las funciones ecológicas de especies de peces, los procesos del ecosistema y los servicios del ecosistema. Aproximadamente entre una cuarta parte y un tercio de las especies de invertebrados bentónicos y de peces (desagregados por etapa de vida; en lo sucesivo especies de peces) ocurrieron en un solo hábitat, y la parte anterior de los arrecifes dominada por Montastraea consistentemente presentó la mayor riqueza de todas las especies, procesos y servicios. Los 11 hábitats fueron necesarios para representar a las 277 especies de peces en el paisaje marino, aunque al reducir el objetivo de conservación a 95% de las especies se requería aproximadamente la mitad de los hábitats para asegurar la representación. Los índices de acumulación de especies (IAE) fueron utilizados para comparar la eficacia de sustitutos y reveló que las especies de peces eran un sustituto más adecuado de las especies bentónicas (IAE = 71%) que las especies bentónicas fueron para los peces (IAE = 42%). Las especies de peces de arrecifes también se distribuyeron más ampliamente que los invertebrados y, por lo tanto, su uso como sustitutos simultáneamente incluyó hábitats en manglares, pastos marinos y arrecifes de coral. Las clases funcionales de peces sirvieron como sustitutos efectivos de especies de peces y bentónicas, lo cual, por la facilidad con que son muestreadas, las hace una medida particularmente útil para la planificación de la conservación. Los procesos y servicios del ecosistema exhibieron gran redundancia entre hábitats y fueron ineficientes como sustitutos de especies. Por lo tanto, los procesos y servicios en este caso fueron inadecuados para un método de diseño de reservas basado en complementariedad. En contraste, la representación de especies o clases funcionales aseguró la inclusión de todos los procesos y servicios en la red de reservas.Resumen: Los mapas de hábitat a menudo son el núcleo de datos espacialmente consistentes sobre el cual se diseñan las redes de reservas marinas, pero su eficacia como sustitutos de la riqueza de especies y su aplicabilidad en otras medidas de conservación es poco conocida. Combinando el análisis de datos de campo, revisión de literatura y evaluación de expertos de un grupo de trabajo multidisciplinario, examinamos el grado en que los hábitats Caribeños proporcionan información útil para la planificación sobre 4 medidas de conservación: riqueza de especies, las funciones ecológicas de especies de peces, los procesos del ecosistema y los servicios del ecosistema. Aproximadamente entre una cuarta parte y un tercio de las especies de invertebrados bentónicos y de peces (desagregados por etapa de vida; en lo sucesivo especies de peces) ocurrieron en un solo hábitat, y la parte anterior de los arrecifes dominada por Montastraea consistentemente presentó la mayor riqueza de todas las especies, procesos y servicios. Los 11 hábitats fueron necesarios para representar a las 277 especies de peces en el paisaje marino, aunque al reducir el objetivo de conservación a 95% de las especies se requería aproximadamente la mitad de los hábitats para asegurar la representación. Los índices de acumulación de especies (IAE) fueron utilizados para comparar la eficacia de sustitutos y reveló que las especies de peces eran un sustituto más adecuado de las especies bentónicas (IAE = 71%) que las especies bentónicas fueron para los peces (IAE = 42%). Las especies de peces de arrecifes también se distribuyeron más ampliamente que los invertebrados y, por lo tanto, su uso como sustitutos simultáneamente incluyó hábitats en manglares, pastos marinos y arrecifes de coral. Las clases funcionales de peces sirvieron como sustitutos efectivos de especies de peces y bentónicas, lo cual, por la facilidad con que son muestreadas, las hace una medida particularmente útil para la planificación de la conservación. Los procesos y servicios del ecosistema exhibieron gran redundancia entre hábitats y fueron ineficientes como sustitutos de especies. Por lo tanto, los procesos y servicios en este caso fueron inadecuados para un método de diseño de reservas basado en complementariedad. En contraste, la representación de especies o clases funcionales aseguró la inclusión de todos los procesos y servicios en la red de reservas.
Since the mass mortality of the urchin Diadema antillarum in 1983, parrotfishes have become the d... more Since the mass mortality of the urchin Diadema antillarum in 1983, parrotfishes have become the dominant grazer on Caribbean reefs. The grazing capacity of these fishes could be impaired if marine reserves achieve their long-term goal of restoring large consumers, several of which prey on parrotfishes. Here we compare the negative impacts of enhanced predation with the positive impacts of reduced fishing mortality on parrotfishes inside reserves. Because large-bodied parrotfishes escape the risk of predation from a large piscivore (the Nassau grouper), the predation effect reduced grazing by only 4 to 8%. This impact was overwhelmed by the increase in density of large parrotfishes, resulting in a net doubling of grazing. Increased grazing caused a fourfold reduction in the cover of macroalgae, which, because they are the principal competitors of corals, highlights the potential importance of reserves for coral reef resilience.
Abstract. Pieces of coral rubble (Porites porites), collected from across 3 fringing reefs that l... more Abstract. Pieces of coral rubble (Porites porites), collected from across 3 fringing reefs that lie along a eutrophication gradient, were examined for the presence of clionid sponges. A similarity analysis of species composition showed that reef zone had less effect on clionid community composition than did other factors affecting the reefs as a whole. Except on the back reef, the Zones, distances, and depths within the reefs had no significant influence on the number of clionid invasions. Reef comparisons demonstrated that clionid abundance increased with increasing eutrophication. Clionids were found in 41% of the pieces collected from the most eutrophic site vs. 24% from the least eutrophic. Because clionids are the principal bio-eroders of coral reefs, any increase in their abundance will likely result in greater bioerosion rates. The mean abundance of Type 3 corals (in which fragmentation is the primary mode of propagation) is positively related to the frequency of boring sponge invasion. suggesting that increased bioerosion may be partly responsible for community shifts toward Type 3 corals in polluted waters. Cliona cf. vastifica, found for the first time in Barbados, flourishes on the most eutrophic reef and may become an important bioeroder under the highly eutrophic conditions that have begun to plague West Indian reefs. Two new species of Cliona (Porifera: Hadro-merida: Clionidae) are described.
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