• Energy Research

AbstractCoral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3–4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6–7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates.

AbstractCoral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3–4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6–7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates.

Anthropogenic activities have caused profound changes globally in biodiversity, species interactions and ecosystem functions and services. In terrestrial systems, restoration has emerged as a useful approach to mitigate these changes, and is increasingly recognised as a tool to fortify ecosystems against future disturbances. In marine systems, restoration is also gaining traction as a management tool, but it is still comparatively scant and underdeveloped relative to terrestrial environments. Key coastal habitats, such as seaweed forests and seagrass meadows are showing widespread patterns of decline around the world. As these important ecosystems increasingly become the target of emerging marine restoration campaigns, it is important not only to address current environmental degradation issues, but also to focus on the future. Given the rate at which marine and other environments are changing, and given predicted increases in the frequency and magnitude of multiple stressors, we argue for an urgent need for subtidal marine macrophyte restoration efforts that explicitly incorporate future-proofing in their goals. Here we highlight emerging scientific techniques that can help achieve this, and discuss changes to managerial, political and public frameworks that are needed to support scientific innovation and restoration applications at scale.

Anthropogenic activities have caused profound changes globally in biodiversity, species interactions and ecosystem functions and services. In terrestrial systems, restoration has emerged as a useful approach to mitigate these changes, and is increasingly recognised as a tool to fortify ecosystems against future disturbances. In marine systems, restoration is also gaining traction as a management tool, but it is still comparatively scant and underdeveloped relative to terrestrial environments. Key coastal habitats, such as seaweed forests and seagrass meadows are showing widespread patterns of decline around the world. As these important ecosystems increasingly become the target of emerging marine restoration campaigns, it is important not only to address current environmental degradation issues, but also to focus on the future. Given the rate at which marine and other environments are changing, and given predicted increases in the frequency and magnitude of multiple stressors, we argue for an urgent need for subtidal marine macrophyte restoration efforts that explicitly incorporate future-proofing in their goals. Here we highlight emerging scientific techniques that can help achieve this, and discuss changes to managerial, political and public frameworks that are needed to support scientific innovation and restoration applications at scale.

Vergés and Campbell introduce the kelp forest ecosystem.

Vergés and Campbell introduce the kelp forest ecosystem.

Significance Most studies of the impact of global warming focus on the direct physiological impacts of climate change. However, global warming is shifting the distribution of many species and leading to novel interactions between previously separated species that have the potential to transform entire ecological communities. This study shows that an increase in the proportion of warmwater species (“tropicalization”) as oceans warm is increasing fish herbivory in kelp forests, contributing to their decline and subsequent persistence in alternate “kelp-free” states. These tropical and subtropical herbivores are increasingly impacting temperate algal communities worldwide, posing a significant threat to the long-term stability of these iconic ecosystems and the valuable services they provide.