Long-Term Evolution of the Guadeloupean Shoreline (1950–2017)

Insular environments have long been recognized as sensitive to issues linked to natural forces that occur every day (swells, currents, and winds) or that are exceptional (storms and cyclones). However, over the past few decades, additional pressure has arisen throughout many already-fragile islands: anthropization, the modification of natural areas by humans and for human usage. Since the 1970s, the number of tourists visiting Guadeloupe Island has strongly increased, driving coastline modifications (building of houses, hotels, diving clubs, etc.). Using panchromatic and high -resolution aerial imagery, the evolution of the coastline from 1950 to 2017 of 19 Guadeloupean beaches was assessed. This evolution was compared with a coastal vulnerability index to determine the sensitivity to morphological, hydrodynamic, and anthropic factors of each studied beach. The results showed that the Guadeloupe coast has become increasingly urbanized since the 1950s, with a transition from 4% of manmade structures along the shoreline in 1950 to 18% in 2017 across the study sites. Across all beaches, coastal erosion was noted and was caused by the simultaneous action of natural factors (hydrodynamics, storms, etc.) or anthropogenic factors (mass tourism, economic development, etc.). Overall, this study highlights the issue of coastal artificialization in Guadeloupe. To avoid irreversible detrimental effects of coastal degradation on the local population and the country???s economy, new decisions favoring natural coastal environment buffers must be made rapidly

Widespread diversity deficits of coral reef sharks and rays

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities

Author Correction: Global status and conservation potential of reef sharks

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.</p

Widespread diversity deficits of coral reef sharks and rays

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at 34 to 47% of surveyed reefs. As reefs become more shark-depleted, rays begin to dominate assemblages. Shark-dominated assemblages persist in wealthy nations with strong governance and in highly protected areas, whereas poverty, weak governance, and a lack of shark management are associated with depauperate assemblages mainly composed of rays. Without action to address these diversity deficits, loss of ecological function and ecosystem services will increasingly affect human communities

Global status and conservation potential of reef sharks

Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats3. Here we address this knowledge gap using data from more than 15,000 standardized baited remote underwater video stations that were deployed on 371 reefs in 58 nations to estimate the conservation status of reef sharks globally. Our results reveal the profound impact that fishing has had on reef shark populations: we observed no sharks on almost 20% of the surveyed reefs. Reef sharks were almost completely absent from reefs in several nations, and shark depletion was strongly related to socio-economic conditions such as the size and proximity of the nearest market, poor governance and the density of the human population. However, opportunities for the conservation of reef sharks remain: shark sanctuaries, closed areas, catch limits and an absence of gillnets and longlines were associated with a substantially higher relative abundance of reef sharks. These results reveal several policy pathways for the restoration and management of reef shark populations, from direct top-down management of fishing to indirect improvement of governance conditions. Reef shark populations will only have a high chance of recovery by engaging key socio-economic aspects of tropical fisheries