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As atmospheric levels of CO(2) increase, reef-building corals are under greater stress from both increased sea surface temperatures and declining sea water pH. To date, most studies have focused on either coral bleaching due to warming oceans or declining calcification due to decreasing oceanic carbonate ion concentrations. Here, through the use of physiology measurements and cDNA microarrays, we show that changes in pH and ocean chemistry consistent with two scenarios put forward by the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, before affects on biomineralisation are apparent at the phenotype level. Under high CO(2) conditions corals at the phenotype level lost over half their Symbiodinium populations, and had a decrease in both photosynthesis and respiration. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrate upregulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur before impacts on calcification.

Massive, long-lived deep-sea red tree corals (Primnoa pacifica) form a solid, layered axis comprised of calcite and gorgonin skeleton. They are abundant on the outer continental shelf and upper slope of the Northeast Pacific, providing habitat for fish and invertebrates. Yet, their large size and arborescent morphology makes them susceptible to disturbance from fishing activities. A better understanding of their growth patterns will facilitate in-situ estimates of population age structure and biomass. Here, we evaluated relationships between ages, growth rates, gross morphological characteristics, and banding patterns in 11 colonies collected from depths of ~141–335 m off the Alaskan coast. These corals ranged in age from 12 to 80 years old. They grew faster radially (0.33–0.74 mm year-1) and axially (2.41–6.39 cm year-1) than in previously measured older colonies, suggesting that growth in P. pacifica declines slowly with age, and that basal diameter and axial height eventually plateau. However, since coral morphology correlated with age in younger colonies (< century), we developed an in-situ age estimation technique for corals from the Northeast Pacific Ocean providing a non-invasive method for evaluating coral age without removing colonies from the population. Furthermore, we determined that annual bands provided the most accurate means for determining coral age in live-collected corals, relative to radiometric dating. Taken together, this work provides insight into P. pacifica growth patterns to inform coastal managers about the demographics of this ecologically important species. With this new ability to estimate the age of red tree corals in-situ, we can readily determine the age-class structure and consequently, the maturity status of thickets, using non-invasive video survey techniques when coupled with mensuration systems such as lasers or stereo-cameras. Enhanced surveys could identify which populations are most vulnerable to disturbance from human activities, and which should be highlighted for protection.

Recent shifts in the geographic distribution of marine species have been linked to shifts in preferred thermal habitats. These shifts in distribution have already posed challenges for living marine resource management, and there is a strong need for projections of how species might be impacted by future changes in ocean temperatures during the 21st century. We modeled thermal habitat for 686 marine species in the Atlantic and Pacific oceans using long-term ecological survey data from the North American continental shelves. These habitat models were coupled to output from sixteen general circulation models that were run under high (RCP 8.5) and low (RCP 2.6) future greenhouse gas emission scenarios over the 21st century to produce 32 possible future outcomes for each species. The models generally agreed on the magnitude and direction of future shifts for some species (448 or 429 under RCP 8.5 and RCP 2.6, respectively), but strongly disagreed for other species (116 or 120 respectively). This allowed us to identify species with more or less robust predictions. Future shifts in species distributions were generally poleward and followed the coastline, but also varied among regions and species. Species from the U.S. and Canadian west coast including the Gulf of Alaska had the highest projected magnitude shifts in distribution, and many species shifted more than 1000 km under the high greenhouse gas emissions scenario. Following a strong mitigation scenario consistent with the Paris Agreement would likely produce substantially smaller shifts and less disruption to marine management efforts. Our projections offer an important tool for identifying species, fisheries, and management efforts that are particularly vulnerable to climate change impacts.

The Abrolhos Bank (eastern Brazil) encompasses the largest and richest coral reefs of the South Atlantic. Coral reef benthic assemblages of the region were monitored from 2003 to 2008. Two habitats (pinnacles' tops and walls) were sampled per site with 3-10 sites sampled within different reef areas. Different methodologies were applied in two distinct sampling periods: 2003-2005 and 2006-2008. Spatial coverage and taxonomic resolution were lower in the former than in the latter period. Benthic assemblages differed markedly in the smallest spatial scale, with greater differences recorded between habitats. Management regimes and biomass of fish functional groups (roving and territorial herbivores) had minor influences on benthic assemblages. These results suggest that local environmental factors such as light, depth and substrate inclination exert a stronger influence on the structure of benthic assemblages than protection from fishing. Reef walls of unprotected coastal reefs showed highest coral cover values, with a major contribution of Montastraea cavernosa (a sediment resistant species that may benefit from low light levels). An overall negative relationship between fleshy macroalgae and slow-growing reef-building organisms (i.e. scleractinians and crustose calcareous algae) was recorded, suggesting competition between these organisms. The opposite trend (i.e. positive relationships) was recorded for turf algae and the two reef-building organisms, suggesting beneficial interactions and/or co-occurrence mediated by unexplored factors. Turf algae cover increased across the region between 2006 and 2008, while scleractinian cover showed no change. The need of a continued and standardized monitoring program, aimed at understanding drivers of change in community patterns, as well as to subsidize sound adaptive conservation and management measures, is highlighted.

Ecological communities show great variation in species richness, composition and food web structure across similar and diverse ecosystems. Knowledge of how this biodiversity relates to ecosystem functioning is important for understanding the maintenance of diversity and the potential effects of species losses and gains on ecosystems. While research often focuses on how variation in species richness influences ecosystem processes, assessing species richness in a food web context can provide further insight into the relationship between diversity and ecosystem functioning and elucidate potential mechanisms underpinning this relationship. Here, we assessed how species richness and trophic diversity affect decomposition rates in a complete aquatic food web: the five trophic level web that occurs within water-filled leaves of the northern pitcher plant, Sarracenia purpurea. We identified a trophic cascade in which top-predators--larvae of the pitcher-plant mosquito--indirectly increased bacterial decomposition by preying on bactivorous protozoa. Our data also revealed a facultative relationship in which larvae of the pitcher-plant midge increased bacterial decomposition by shredding detritus. These important interactions occur only in food webs with high trophic diversity, which in turn only occur in food webs with high species richness. We show that species richness and trophic diversity underlie strong linkages between food web structure and dynamics that influence ecosystem functioning. The importance of trophic diversity and species interactions in determining how biodiversity relates to ecosystem functioning suggests that simply focusing on species richness does not give a complete picture as to how ecosystems may change with the loss or gain of species.

The aesthetic appreciation of natural places is one of the most fundamental ways in which people relate to their environment. It provides wellbeing, an opportunity for recreation and reflection, a sense of place, and cultural enrichment. It also motivates people to take care of natural places and to conserve them for current and future appreciation. Aesthetically valuable places also support significant economic activity. However, there is little guidance available to assist environmental managers and policy-makers to consider and integrate aesthetic values into decision-making processes. In this study, we present an approach for developing robust and practical indicators of aesthetic value to enable environmental managers to consider, assess and report on aesthetic condition and trend. We demonstrate its utility using the case of the Great Barrier Reef, a region currently undergoing significant social, economic and environmental change and an area formally protected, in part, for its aesthetic values. A qualitative scoping study with 30 key informants identified over 180 potential qualities contributing to reef aesthetics. We tested five for their utility in capturing key aspects of the coral reef aesthetic: (i) coral cover, (ii) coral pattern, (iii) coral topography, (iv) fish abundance, and (v) visibility. We asked 1,417 online Australians to aesthetically rate 50 out of 181 underwater coral reef images that varied in relation to these five attributes. Coral topography, fish abundance, and visibility were significantly correlated with aesthetic ratings, whilst coral cover and coral pattern were not. We also tested for demographic patterns in aesthetic ratings. Our pilot study has demonstrated that readily measurable characteristics of coral reefs can provide useful indicators of aesthetic quality, opening up opportunities for coral reef managers and policymakers to assess and track changes in aesthetics in ways that are relevant to the public. There is considerable scope to further advance capacity for monitoring and managing aesthetic values of coral reefs through additional research that resolves nuances in the meanings associated with aesthetics in coral reef settings.

Climate change and decadal variability are impacting marine fish and invertebrate species worldwide and these impacts will continue for the foreseeable future. Quantitative approaches have been developed to examine climate impacts on productivity, abundance, and distribution of various marine fish and invertebrate species. However, it is difficult to apply these approaches to large numbers of species owing to the lack of mechanistic understanding sufficient for quantitative analyses, as well as the lack of scientific infrastructure to support these more detailed studies. Vulnerability assessments provide a framework for evaluating climate impacts over a broad range of species with existing information. These methods combine the exposure of a species to a stressor (climate change and decadal variability) and the sensitivity of species to the stressor. These two components are then combined to estimate an overall vulnerability. Quantitative data are used when available, but qualitative information and expert opinion are used when quantitative data is lacking. Here we conduct a climate vulnerability assessment on 82 fish and invertebrate species in the Northeast U.S. Shelf including exploited, forage, and protected species. We define climate vulnerability as the extent to which abundance or productivity of a species in the region could be impacted by climate change and decadal variability. We find that the overall climate vulnerability is high to very high for approximately half the species assessed; diadromous and benthic invertebrate species exhibit the greatest vulnerability. In addition, the majority of species included in the assessment have a high potential for a change in distribution in response to projected changes in climate. Negative effects of climate change are expected for approximately half of the species assessed, but some species are expected to be positively affected (e.g., increase in productivity or move into the region). These results will inform research and management activities related to understanding and adapting marine fisheries management and conservation to climate change and decadal variability.