A critical assessment of data derived from coral cay conservation volunteers

Since 1986, Coral Cay Conservation (CCC) has utilized a workforce of over 900 specially-trained volunteer divers to collect detailed topographic, bathymetric and biological data for the establishment of management plans for selected areas of the Belize barrier reef. The biological data recorded are ordinal and reflect the abundance of reef organisms including fish, macroalgae and hermatypic corals on a scale of 0-5. Substrate composition and the coverage of principal biotic classes are also visually assessed using an ordinal scale of 0-5. An exercise was carried out to assess the accuracy and consistency of data recorded by volunteers. Transects were laid in each of the major reef zones and in lagoon habitats. Each transect was surveyed independently by six teams of trained volunteers and compared to a reference obtained by experienced CCC staff. Analyses were carried out to test the accuracy and consistency of the coral, macroalgal and habitat data. Further analyses sought to quantify the proportion of species correctly identified, the frequency of erroneous species recordings and the variation of abundance ratings. The overall accuracy of coral surveys varied from 52-70% with the poorer values obtained in deeper outer and inner drop-off reef zones. The trend of reduced surveyor performance in deeper water is discussed in terms of physical, physiological and psychological phenomena. Inter-group consistency exhibited a similar bathymetric trend to that found for coral accuracy. Macroalgae were generally accurately and consistently recorded. No clear trend of improved accuracy and consistency following greater survey experience was apparent. Substrate composition and biological cover were recorded with an accuracy exceeding 90% in seagrass habitats and 70-90% in reef sites. A number of recommendations are made to improve survey methodology and volunteer training

Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs

The fisheries and biodiversity benefits of marine reserves are widely recognised but there is mounting interest in exploiting the importance of herbivorous fishes as a tool to help ecosystems recover from climate change impacts. This approach might be particularly suitable for coral reefs, which are acutely threatened by climate change, yet the trophic cascades generated by reserves are strong enough that they might theoretically enhance the rate of coral recovery after disturbance. However, evidence for reserves facilitating coral recovery has been lacking. Here we investigate whether reductions in macroalgal cover, caused by recovery of herbivorous parrotfishes within a reserve, have resulted in a faster rate of coral recovery than in areas subject to fishing. Surveys of ten sites inside and outside a Bahamian marine reserve over a 2.5-year period demonstrated that increases in coral cover, including adjustments for the initial size-distribution of corals, were significantly higher at reserve sites than those in non-reserve sites. Furthermore, macroalgal cover was significantly negatively correlated with the change in total coral cover over time. Recovery rates of individual species were generally consistent with small-scale manipulations on coral-macroalgal interactions, but also revealed differences that demonstrate the difficulties of translating experiments across spatial scales. Size-frequency data indicated that species which were particularly affected by high abundances of macroalgae outside the reserve had a population bottleneck restricting the supply of smaller corals to larger size classes. Importantly, because coral cover increased from a heavily degraded state, and recovery from such states has not previously been described, similar or better outcomes should be expected for many reefs in the region. Reducing herbivore exploitation as part of an ecosystem-based management strategy for coral reefs appears to be justified

Uniting paradigms of connectivity in marine ecology

The connectivity of marine organisms among habitat patches has been dominated by two independent paradigms with distinct conservation strategies. One paradigm is the dispersal of larvae on ocean currents, which suggests networks of marine reserves. The other is the demersal migration of animals from nursery to adult habitats, requiring the conservation of connected ecosystem corridors. Here, we suggest that a common driver, wave exposure, links larval and demersal connectivity across the seascape. To study the effect of linked connectivities on fish abundance at reefs, we parameterize a demographic model for The Bahamas seascape using maps of habitats, empirically forced models of wave exposure and spatially realistic three-dimensional hydrological models of larval dispersal. The integrated empirical-modeling approach enabled us to study linked connectivity on a scale not currently possible by purely empirical studies. We find sheltered environments not only provide greater nursery habitat for juvenile fish but larvae spawned on adjacent reefs have higher retention, thereby creating a synergistic increase in fish abundance. Uniting connectivity paradigms to consider all life stages simultaneously can help explain the evolution of nursery habitat use and simplifies conservation advice: Reserves in sheltered environments have desirable characteristics for biodiversity conservation and can support local fisheries through adult spillover

Non-consumptive effects of native and invasive predators on juvenile Caribbean parrotfish

Non-consumptive effects of predators can have important impacts on aquatic food webs, but there are few data on how predators change the behaviour of Caribbean reef fishes. Such changes may include behavioural responses to the invasive predatory lionfish (Pterois volitans/P. miles). This study used an aquarium experiment to examine the behaviour of herbivorous parrotfish (Scarus iseri) in the absence of other fish (control), with a non-piscivore present, and with a predatory threat from a native grouper or lionfish. Treatments were repeated with and without additional parrotfish shelters to examine the potential effects of degraded reefs (loss of refuges). Using video, parrotfish behaviours (sheltering, swimming in open areas, foraging, aggressive conspecific interactions, bite rates, and shoaling behaviour) were recorded for groups of four parrotfish. Compared to the control, the average number of parrotfish hiding was reduced by 65 % and foraging shoals were 10 % larger when threatened by grouper, likely as a specific response to an ambush predator. When exposed to lionfish, parrotfish reduced their bite rates by 50 %, possibly to be more vigilant of this predator’s unique stalking behaviour. The absence of additional shelter had limited effects although parrotfish formed 10 % larger shoals when swimming in open water, potentially as a defensive behaviour because of a perceived lack of refuges. The reduction in parrotfish bite rates caused by lionfish may have important demographic consequences. Furthermore, parrotfishes are important grazers of macroalgae, and these behavioural changes may exacerbate the direct effects of lionfish predation and potentially affect reef benthic dynamics

A critical assessment of data derived from Coral Cay Conservation volunteers.

ABSTRACT Since 1986, Coral Cay Conservation (CCC) has utilized a workforce of over 900 speciallytrained volunteer divers to collect detailed topographic, bathymetric and biological data for the establishment of management plans for selected areas of the Belize barrier reef. The biological data recorded are ordinal and reflect the abundance of reef organisms including fish, macroalgae and hermatypic corals on a scale of 0-5. Substrate composition and the coverage of principal biotic classes are also visually assessed using an ordinal scale of 0-5. An exercise was carried out to assess the accuracy and consistency of data recorded by volunteers. Transects were laid in each of the major reef zones and in lagoon habitats. Each transect was surveyed independently by six teams of trained volunteers and compared to a reference obtained by experienced CCC staff. Analyses were carried out to test the accuracy and consistency of the coral, macroalgal and habitat data. Further analyses sought to quantify the proportion of species correctly identified, the frequency of erroneous species recordings and the variation of abundance ratings. The overall accuracy of coral surveys varied from 52-70% with the poorer values obtained in deeper outer and inner drop-off reef zones. The trend of reduced surveyor performance in deeper water is discussed in terms of physical, physiological and psychological phenomena. Inter-group consistency exhibited a similar bathymetric trend to that found for coral accuracy. Macroalgae were generally accurately and consistently recorded. No clear trend of improved accuracy and consistency following greater survey experience was apparent. Substrate composition and biological cover were recorded with an accuracy exceeding 90% in seagrass habitats and 70-90% in reef sites. A number of recommendations are made to improve survey methodology and volunteer training

Marine Reserves Shape Seascapes on Scales Visible From Space

Marine reserves can effectively restore harvested populations, and ‘mega-reserves’ increasingly protect large tracts of ocean. However, no method exists of monitoring ecological responses at this large scale. Herbivory is a key mechanism structuring ecosystems, and this consumer–resource interaction\u27s strength on coral reefs can indicate ecosystem health. We screened 1372, and measured features of 214, reefs throughout Australia\u27s Great Barrier Reef using high-resolution satellite imagery, combined with remote underwater videography and assays on a subset, to quantify the prevalence, size and potential causes of ‘grazing halos’. Halos are known to be seascape-scale footprints of herbivory and other ecological interactions. Here we show that these halo-like footprints are more prevalent in reserves, particularly older ones (approx. 40 years old), resulting in predictable changes to reef habitat at scales visible from space. While the direct mechanisms for this pattern are relatively clear, the indirect mechanisms remain untested. By combining remote sensing and behavioural ecology, our findings demonstrate that reserves can shape large-scale habitat structure by altering herbivores\u27 functional importance, suggesting that reserves may have greater value in restoring ecosystems than previously appreciated. Additionally, our results show that we can now detect macro-patterns in reef species interactions using freely available satellite imagery. Low-cost, ecosystem-level observation tools will be critical as reserves increase in number and scope; further investigation into whether halos may help seems warranted. Significance statement: Marine reserves are a widely used tool to mitigate fishing impacts on marine ecosystems. Predicting reserves\u27 large-scale effects on habitat structure and ecosystem functioning is a major challenge, however, because these effects unfold over longer and larger scales than most ecological studies. We use a unique approach merging remote sensing and behavioural ecology to detect ecosystem change within reserves in Australia\u27s vast Great Barrier Reef. We find evidence of changes in reefs\u27 algal habitat structure occurring over large spatial (thousands of kilometres) and temporal (40+ years) scales, demonstrating that reserves can alter herbivory and habitat structure in predictable ways. This approach demonstrates that we can now detect aspects of reefs\u27 ecological responses to protection even in remote and inaccessible reefs globally

Tropical coastal habitats as surrogates of fish community structure, grazing, and fisheries value

Habitat maps are frequently invoked as surrogates of biodiversity to aid the design of networks of marine reserves. Maps are used to maximize habitat heterogeneity in reserves because this is likely to maximize the number of species protected. However, the technique's efficacy is limited by intra-habitat variability in the species present and their abundances. Although communities are expected to vary among patches of the same habitat, this variability is poorly documented and rarely incorporated into reserve planning. To examine intra-habitat variability in coral-reef fishes, we generated a data set from eight tropical coastal habitats and six islands in the Bahamian archipelago using underwater visual censuses. Firstly, we provide further support for habitat heterogeneity as a surrogate of biodiversity as each predefined habitat type supported a distinct assemblage of fishes. Intrahabitat variability in fish community structure at scales of hundreds of kilometers (among islands) was significant in at least 75% of the habitats studied, depending on whether presence/absence, density, or biomass data were used. Intra-habitat variability was positively correlated with the mean number of species in that habitat when density and biomass data were used. Such relationships provide a proxy for the assessment of intra-habitat variability when detailed quantitative data are scarce. Intra-habitat variability was examined in more detail for one habitat (forereefs visually dominated by Montastraea corals). Variability in community structure among islands was driven by small, demersal families (e. g., territorial pomacentrid and labrid fishes). Finally, we examined the ecological and economic significance of intra-habitat variability in fish assemblages on Montastraea reefs by identifying how this variability affects the composition and abundances of fishes in different functional groups, the key ecosystem process of parrotfish grazing, and the ecosystem service of value of commercially important finfish. There were significant differences in a range of functional groups and grazing, but not fisheries value. Variability at the scale of tens of kilometers (among reefs around an island) was less than that among islands. Caribbean marine reserves should be replicated at scales of hundreds of kilometers, particularly for species-rich habitats, to capture important intra-habitat variability in community structure, function, and an ecosystem process

A theory-based framework for understanding the establishment, persistence, and diffusion of community-based conservation

Over decades, biodiversity conservation researchers and practitioners have developed theories and conceptual frameworks to inform the planning, implementation, and evaluation of community-based conservation (CBC). While a diversity of mechanisms for understanding and supporting CBC has helped tailor approaches to local needs and conditions, the absence of a unified lens to understand CBC has limited the capacity for integrating foundational theory into practice more systemically, and for learning across different projects, stakeholders, and institutions. We introduce a theory-based framework called “the CBC framework” that draws upon three foundational theories from sociology, economics, and political science to understand the establishment, persistence, and diffusion of CBC. Experience applying aspects of the framework within different conservation organizations demonstrates how this integrative approach can provide a gateway for practitioners to engage with social science theory to understand the status and context of CBC interventions and efforts. For practitioners, scientists, evaluators, and strategists, the framework can guide the design of CBC interventions and monitoring and evaluation systems to facilitate theory-based learning and enable evidence-informed decision-making. Approaches like the CBC framework that facilitate collaborative planning, evaluation, and research can help better integrate social science theory in conservation practice while increasing the capacity for conservation scientists, practitioners, and stakeholders to learn together and adaptively manage CBC to deliver positive results for both people and nature

Mangroves enhance the biomass of coral reef fish communities in the Caribbean

Mangrove forests are one of the world's most threatened tropical ecosystems with global loss exceeding 35% (ref. 1). Juvenile coral reef fish often inhabit mangroves, but the importance of these nurseries to reef fish population dynamics has not been quantified. Indeed, mangroves might be expected to have negligible influence on reef fish communities: juvenile fish can inhabit alternative habitats and fish populations may be regulated by other limiting factors such as larval supply or fishing. Here we show that mangroves are unexpectedly important, serving as an intermediate nursery habitat that may increase the survivorship of young fish. Mangroves in the Caribbean strongly influence the community structure of fish on neighbouring coral reefs. In addition, the biomass of several commercially important species is more than doubled when adult habitat is connected to mangroves. The largest herbivorous fish in the Atlantic, Scarus guacamaia, has a functional dependency on mangroves and has suffered local extinction after mangrove removal. Current rates of mangrove deforestation are likely to have severe deleterious consequences for the ecosystem function, fisheries productivity and resilience of reefs. Conservation efforts should protect connected corridors of mangroves, seagrass beds and coral reefs

Editorial: Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK

Editorial on the Research Topic Coral Reefs in the Anthropocene – Reflecting on 20 Years of Reef Conservation UK.N