Resource type influences the effects of reserves and connectivity on ecological functions.

Connectivity is a pivotal feature of landscapes that affects the structure of populations and the functioning of ecosystems. It is also a key consideration in conservation planning. But the potential functional effects of landscape connectivity are rarely evaluated in a conservation context. The removal of algae by herbivorous fish is a key ecological function on coral reefs that promotes coral growth and recruitment. Many reef herbivores are harvested and some use other habitats (like mangroves) as nurseries or feeding areas. Thus, the effects of habitat connectivity and marine reserves can jointly promote herbivore populations on coral reefs, thereby influencing reef health. We used a coral reef seascape in eastern Australia to test whether seascape connectivity and reserves influence herbivory. We measured herbivore abundance and rates of herbivory (on turf algae and macroalgae) on reefs that differed in both their level of connectivity to adjacent mangrove habitats and their level of protection from fishing. Reserves enhanced the biomass of herbivorous fish on coral reefs in all seascape settings and promoted consumption of turf algae. Consumption of turf algae was correlated with the biomass of surgeonfish that are exploited outside reserves. By contrast, both reserve status and connectivity influenced herbivory on macroalgae. Consumption of macroalgae was greatest on fished reefs that were far from mangroves and was not strongly correlated with any fish species. Our findings demonstrate that landscape connectivity and reserve status can jointly affect the functioning of ecosystems. Moreover, we show that reserve and connectivity effects can differ markedly depending on resource type (in this case turf algae vs. macroalgae). The effectiveness of conservation initiatives will therefore depend on our ability to understand how these multiple interactive effects structure the distribution of ecological functions. These findings have wider implications for the spatial conservation of heterogeneous environments and strengthen the case that the impact of conservation on ecosystem functioning is contingent on how reserves are positioned in landscapes.

Yabsley NA ，Olds AD ，Connolly RM ，Martin TS ，Gilby BL ，Maxwell PS ，Huijbers CM ，Schoeman DS ，Schlacher TA ... -  《-》

Marine reserves help coastal ecosystems cope with extreme weather.

Natural ecosystems have experienced widespread degradation due to human activities. Consequently, enhancing resilience has become a primary objective for conservation. Nature reserves are a favored management tool, but we need clearer empirical tests of whether they can impart resilience. Catastrophic flooding in early 2011 impacted coastal ecosystems across eastern Australia. We demonstrate that marine reserves enhanced the capacity of coral reefs to withstand flood impacts. Reserve reefs resisted the impact of perturbation, whilst fished reefs did not. Changes on fished reefs were correlated with the magnitude of flood impact, whereas variation on reserve reefs was related to ecological variables. Herbivory and coral recruitment are critical ecological processes that underpin reef resilience, and were greater in reserves and further enhanced on reserve reefs near mangroves. The capacity of reserves to mitigate external disturbances and promote ecological resilience will be critical to resisting an increased frequency of climate-related disturbance.

Olds AD ，Pitt KA ，Maxwell PS ，Babcock RC ，Rissik D ，Connolly RM ... -  《-》

Distribution, behavior, and condition of herbivorous fishes on coral reefs track algal resources.

Tootell JS ，Steele MA 《-》

Consumer diversity interacts with prey defenses to drive ecosystem function.

Rasher DB ，Hoey AS ，Hay ME 《ECOLOGY》

Morphological and ecological trait diversity reveal sensitivity of herbivorous fish assemblages to coral reef benthic conditions.

Herbivorous fishes play a critical role in the maintenance of coral reefs through grazing and cropping of various benthic algae types. Herbivorous fish assemblages are sensitive to changes in the reef environment and are often targeted by local fisheries. This can lead to a decline in ecosystem functions if key groups are reduced. The present study investigates the morphological and ecological trait diversity of herbivorous reef fish assemblages in habitats differing in relative benthic coverage: i) coral-dominated, ii) algae-dominated, and iii) an intermediate habitat. Trait diversity for conspicuous herbivorous fishes was measured using three trait diversity indices: trait richness, trait divergence, and trait evenness. These indices were derived from in situ community surveys and feeding observations, morphological assessment of feeding mechanics from locally collected specimens, and ecological information obtained from published data. Trait diversity, reflected in higher trait evenness and lower trait richness, was lower within algae-dominated habitats than coral-dominated habitats, suggesting that algae-dominated habitats may be compromised by the lack of essential functions provided by key species. These groups reduce algal biomass and may help facilitate the survival and growth of corals, which in turn can increase coral cover. Algae-habitats were dominated with species known to consume macroalgae (rabbitfish and surgeonfish), appearing to provide essential feeding and habitat resources. These species include browsers and croppers that are fundamental in reducing algal biomass and may help facilitate the survival and growth of corals, which in turn can promote reef health. However, this habitat lacked parrotfishes known to remove turf algae and sediments, an essential function for clearing benthic space for coral settlement and other key benthic invertebrates. This study identified several species with overlapping functional roles in the coral-dominated and intermediate habitats. Still, species that were not redundant showed high trait complementarity, suggesting that their removal may result in the loss of unique functions. Importantly, we show that algae-dominated habitats supported high numbers of juvenile fishes especially in species targeted by local artisanal fishers. We also showed that the loss of trait diversity is greater than the loss of species diversity through the comparison of taxonomic and trait β-diversity, further emphasizing the importance of trait diversity analysis in understanding ecosystem health and maintenance.

Pombo-Ayora L ，Coker DJ ，Carvalho S ，Short G ，Berumen ML ... -  《-》