Coral reefs are in decline worldwide and monitoring activities are important for assessing the impact of disturbance on reefs and tracking subsequent recovery or decline. Monitoring by field surveys ...provides accurate data but at highly localised scales and so is not cost-effective for reef scale monitoring at frequent time points. Remote sensing from satellites is an alternative and complementary approach. While remote sensing cannot provide the level of detail and accuracy at a single point than a field survey, the statistical power for inferring large scale patterns benefits in having complete areal coverage. This review considers the state of the art of coral reef remote sensing for the diverse range of objectives relevant for management, ranging from the composition of the reef: physical extent, benthic cover, bathymetry, rugosity; to environmental parameters: sea surface temperature, exposure, light, carbonate chemistry. In addition to updating previous reviews, here we also consider the capability to go beyond basic maps of habitats or environmental variables, to discuss concepts highly relevant to stakeholders, policy makers and public communication: such as biodiversity, environmental threat and ecosystem services. A clear conclusion of the review is that advances in both sensor technology and processing algorithms continue to drive forward remote sensing capability for coral reef mapping, particularly with respect to spatial resolution of maps, and synthesis across multiple data products. Both trends can be expected to continue.
The shape of success in a turbulent world Bejarano, Sonia; Jouffray, Jean-Baptiste; Chollett, Iliana ...
Functional ecology,
June 2017, Letnik:
31, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Summary
While environmental filters are well‐known factors influencing community assembly, the extent to which these modify species functions, and entire ecosystem processes, is poorly understood.
...Focusing on a high‐diversity system, we ask whether environmental filtering has ecosystem‐wide effects beyond community assembly. We characterise a coral reef herbivorous fish community for swimming performance based on ten functional traits derived from fish morphology. We then investigate whether wave exposure modifies the functional make‐up of herbivory, and the absolute and relative feeding frequency of distinct feeding functional groups.
Herbivorous fish species conformed to either laterally compressed or fusiform body plans, which differ in their morphological design to minimise drag. High wave exposure selectively limited the feeding function of the deepest body shapes with highest caudal thrust efficiency, and favoured fusiform bodies irrespective of pectoral fin shape.
Traditionally recognised herbivore feeding functional groups (i.e. grazers–detritivores and scrapers–small excavators) differed in swimming performance, and in their capacity to feed consistently across levels of wave exposure. We therefore emphasise the distinctness of their ecological niche and functional complementarity.
Species within the same feeding functional group also had contrasting responses to wave exposure. We thereby reveal a further ecological dimension of niche partitioning, and reiterate the risk of assuming functional redundancy among species with a common feeding mode.
Contrasting responses of species within feeding functional roles (i.e. response diversity) allowed the preservation of critical trophic functions throughout the gradient (e.g. macroalgal browsing), and likely explained why overall levels of herbivory were robust to filtering. Whether ecosystem functioning will remain robust under the additive effects of environmental stress and human‐induced disturbances remains to be tested.
A lay summary is available for this article.
Lay Summary
Under projections of global climate change and other stressors, significant changes in the ecology, structure and function of coral reefs are predicted. Current management strategies tend to look to ...the past to set goals, focusing on halting declines and restoring baseline conditions. Here, we explore a complementary approach to decision making that is based on the anticipation of future changes in ecosystem state, function and services. Reviewing the existing literature and utilizing a scenario planning approach, we explore how the structure of coral reef communities might change in the future in response to global climate change and overfishing. We incorporate uncertainties in our predictions by considering heterogeneity in reef types in relation to structural complexity and primary productivity. We examine 14 ecosystem services provided by reefs, and rate their sensitivity to a range of future scenarios and management options. Our predictions suggest that the efficacy of management is highly dependent on biophysical characteristics and reef state. Reserves are currently widely used and are predicted to remain effective for reefs with high structural complexity. However, when complexity is lost, maximizing service provision requires a broader portfolio of management approaches, including the provision of artificial complexity, coral restoration, fish aggregation devices and herbivore management. Increased use of such management tools will require capacity building and technique refinement and we therefore conclude that diversification of our management toolbox should be considered urgently to prepare for the challenges of managing reefs into the 21st century.
Reef managers cannot fight global warming through mitigation at local scale, but they can use information on thermal patterns to plan for reserve networks that maximize the probability of persistence ...of their reef system. Here we assess previous methods for the design of reserves for climate change and present a new approach to prioritize areas for conservation that leverages the most desirable properties of previous approaches. The new method moves the science of reserve design for climate change a step forwards by: (1) recognizing the role of seasonal acclimation in increasing the limits of environmental tolerance of corals and ameliorating the bleaching response; (2) using the best proxy for acclimatization currently available; (3) including information from several bleaching events, which frequency is likely to increase in the future; (4) assessing relevant variability at country scales, where most management plans are carried out. We demonstrate the method in Honduras, where a reassessment of the marine spatial plan is in progress.
K-selected species with low rates of sexual recruitment may utilise storage effects where low adult mortality allows a number of individuals to persist through time until a favourable recruitment ...period occurs. Alternative methods of recruitment may become increasingly important for such species if the availability of favourable conditions for sexual recruitment decline under rising anthropogenic disturbance and climate change. Here, we test the hypotheses that asexual dispersal is an integral life history strategy not only in branching corals, as previously reported, but also in a columnar, 'K-selected' coral species, and that its prevalence is driven by the frequency of severe hurricane disturbance. Montastraea annularis is a long-lived major frame-work builder of Caribbean coral reefs but its survival is threatened by the consequences of climate induced disturbance, such as bleaching, ocean acidification and increased prevalence of disease. 700 M. annularis samples from 18 reefs within the Caribbean were genotyped using six polymorphic microsatellite loci. We demonstrate that asexual reproduction occurs at varying frequency across the species-range and significantly contributes to the local abundance of M. annularis, with its contribution increasing in areas with greater hurricane frequency. We tested several competing hypotheses that might explain the observed pattern of genotypic diversity. 64% of the variation in genotypic diversity among the sites was explained by hurricane incidence and reef slope, demonstrating that large-scale disturbances combine with local habitat characteristics to shape the balance between sexual and asexual reproduction in populations of M. annularis.
Anthropogenic environmental change has increased coral reef disturbance regimes in recent decades, altering the structure and function of many coral reefs globally. In this study, we used coral ...community survey data collected from 1996 to 2015 to evaluate reef‐scale coral calcification capacity (CCC) dynamics with respect to recorded pulse disturbances for 121 reef sites in the Main Hawaiian Islands and Mo'orea (French Polynesia) in the Pacific and the Florida Keys Reef Tract and St. John (U.S. Virgin Islands) in the western Atlantic. CCC remained relatively high in the Main Hawaiian Islands in the absence of recorded widespread disturbances; declined and subsequently recovered in Mo'orea following a crown‐of‐thorns sea star outbreak, coral bleaching, and major cyclone; decreased and remained low following coral bleaching in the Florida Keys Reef Tract; and decreased following coral bleaching and disease in St. John. Individual coral taxa have variable calcification rates and susceptibility to disturbances because of their differing life‐history strategies. As a result, temporal changes in CCC in this study were driven by shifts in both overall coral cover and coral community composition. Analysis of our results considering coral life‐history strategies showed that weedy corals generally increased their contributions to CCC over time while the contribution of competitive corals decreased. Shifts in contributions by stress‐tolerant and generalist corals to CCC were more variable across regions. The increasing frequency and intensity of disturbances under 21st century global change therefore has the potential to drive lower and more variable CCC because of the increasing dominance of weedy and some stress‐tolerant corals.
Coastal ecosystems and the livelihoods they support are threatened by stressors acting at global and local scales. Here we used the data produced by the Caribbean Coastal Marine Productivity program ...(CARICOMP), the longest, largest monitoring program in the wider Caribbean, to evidence local-scale (decreases in water quality) and global-scale (increases in temperature) stressors across the basin. Trend analyses showed that visibility decreased at 42% of the stations, indicating that local-scale chronic stressors are widespread. On the other hand, only 18% of the stations showed increases in water temperature that would be expected from global warming, partially reflecting the limits in detecting trends due to inherent natural variability of temperature data. Decreases in visibility were associated with increased human density. However, this link can be decoupled by environmental factors, with conditions that increase the flush of water, dampening the effects of human influence. Besides documenting environmental stressors throughout the basin, our results can be used to inform future monitoring programs, if the desire is to identify stations that provide early warning signals of anthropogenic impacts. All CARICOMP environmental data are now available, providing an invaluable baseline that can be used to strengthen research, conservation, and management of coastal ecosystems in the Caribbean basin.
In the search for protecting biodiversity, enhancing sustainable resource use, and minimizing conflict among users, spatial planning is now ubiquitous around the globe. Acquiring maps of fishing ...activity is critical to account for the interests of fishers, but fisheries are generally underrepresented in spatial plans. We conducted a quantitative systematic literature review on how fisheries data have been included in spatial planning. 145 research articles were reviewed. Most studies (99%) assessed marine ecosystems. A kaleidoscope of data sources has been used to map fisheries, from vessel tracking data (11%) to surrogates (17%). Most articles (43%) have focused on mapping fishing effort, but other variables might be more relevant for spatial planning. Stakeholder groups are generally aggregated together (84%), but to achieve socially equitable outcomes, differences in relative importance or vulnerability should be included in the analyses. There ought to be a shift in spatial and temporal scale so that the scale in which fishing activity is recorded matches the scales needed for relevant management. At the planning stage, fishing data have been incorporated mostly to avoid conflict (97%). However, when stocks are overfished, ensuring some areas remain open to fishing and including fisheries in alternative ways to “cost” (which incorporates the economic and social impact of spatial closures) might be necessary. The use of inappropriate fisheries data has produced spatial plans that lead to poor management decisions, social conflict, and lack of compliance. Based on these results, we offer a set of suggestions on how to develop fisheries spatial planning research that will promote environmental and social sustainability.
Red tides have affected marine and coastal communities for centuries. The effects of red tides on commercial capture fisheries have rarely been evaluated, owing in part to a lack of appropriate data. ...Leveraging modeled maps of red tide severity, vessel monitoring systems data, and logbook records, we investigated the commercial fisheries impacts of red tide events in Florida during the period 2008–2019. We focused on the bottom longline and vertical line fisheries targeting reef fishes. Red tides were punctuated events peaking at the end of summer, with 2018 and 2019 the most intense years. The total area affected by intense red tides (concentrations> 1,000 cells/L) was 103,483 km2, about the size of the state of Kentucky. Red tides did not have negative effect on fleet-level fisheries metrics such as number of fishing vessels, trips, fishing effort or revenue (generalized mixed effect models, p > 0.5). Fishing effort was, however, displaced from the red tide areas, and fishers avoided areas characterized by intense blooms (zero-inflated negative binomial model, p < 0.001). Follow up of the long-term likely responses of the resource and the catch are needed to fully understand the consequences of red tide events in commercial fisheries in the Gulf of Mexico.
•Red tides have affected the Florida coast for centuries incurring in economic losses.•Wild reef fisheries have not been affected in terms of fleet-level metrics.•But fishers avoided intense red tide blooms, which caused fisheries displacement.
PDF
