Thermal dependence of cardiac function in arctic fish: implications of a warming world

With the Arctic experiencing one of the greatest and most rapid increases in sea temperatures in modern time, predicting how Arctic marine organisms will respond to elevated temperatures has become crucial for conservation biology. Here, we examined the thermal sensitivity of cardiorespiratory performance for three closely related species of sculpins that inhabit the Arctic waters, two of which, Gymnocanthus tricuspis and Myoxocephalus scorpioides, have adapted to a restricted range within the Arctic, whereas the third species, Myoxocephalus scorpius, has a wider distribution. We tested the hypothesis that the fish restricted to Arctic cold waters would show reduced cardiorespiratory scope in response to an increase in temperature, as compared with the more eurythermal M. scorpius. As expected from their biogeography, M. scorpioides and G. tricuspis maximised cardiorespiratory performance at temperatures between 1 and 4°C, whereas M. scorpius maximised performance over a wider range of temperatures (1-10°C). Furthermore, factorial scope for cardiac output collapsed at elevated temperature for the two high-latitude species, negatively impacting their ability to support aerobically driven metabolic processes. Consequently, these results concurred with our hypothesis, suggesting that the sculpin species restricted to the Arctic are likely to be negatively impacted by increases in ocean temperatures

Effects of CO2 enrichment on photosynthesis, growth, and nitrogen metabolism of the seagrass Zostera noltii

Seagrass ecosystems are expected to benefit from the global increase in CO2 in the ocean because the photosynthetic rate of these plants may be C-i-limited at the current CO2 level. As well, it is expected that lower external pH will facilitate the nitrate uptake of seagrasses if nitrate is cotransported with H+ across the membrane as in terrestrial plants. Here, we investigate the effects of CO2 enrichment on both carbon and nitrogen metabolism of the seagrass Zostera noltii in a mesocosm experiment where plants were exposed for 5 months to two experimental CO2 concentrations (360 and 700 ppm). Both the maximum photosynthetic rate (Pm) and photosynthetic efficiency (alpha) were higher (1.3- and 4.1-fold, respectively) in plants exposed to CO2-enriched conditions. On the other hand, no significant effects of CO2 enrichment on leaf growth rates were observed, probably due to nitrogen limitation as revealed by the low nitrogen content of leaves. The leaf ammonium uptake rate and glutamine synthetase activity were not significantly affected by increased CO2 concentrations. On the other hand, the leaf nitrate uptake rate of plants exposed to CO2-enriched conditions was fourfold lower than the uptake of plants exposed to current CO2 level, suggesting that in the seagrass Z. noltii nitrate is not cotransported with H+ as in terrestrial plants. In contrast, the activity of nitrate reductase was threefold higher in plant leaves grown at high-CO2 concentrations. Our results suggest that the global effects of CO2 on seagrass production may be spatially heterogeneous and depend on the specific nitrogen availability of each system. Under a CO2 increase scenario, the natural levels of nutrients will probably become limiting for Z. noltii. This potential limitation becomes more relevant because the expected positive effect of CO2 increase on nitrate uptake rate was not confirmed.Fundacao para a Ciencia e a Tecnologia [SFRH/BD/21487/2005]; POCI; FSE; COST; EC; EUinfo:eu-repo/semantics/publishedVersio

Global warming and mass extinctions associated with large igneous province volcanism

The coincidence of large igneous province (LIP) eruptions with at least three, if not all of the “Big Five” biotic crises of the Phanerozoic implies that volcanism is a key driver of mass extinctions. Many LIP-induced extinction scenarios invoke global warming, caused primarily (but not exclusively) by greenhouse gases emitted at the site of LIP emplacement and by contact metamorphism of carbon-rich host rocks. Here we explore a) the climate-changing products of volcanism including sulfur dioxide (SO2), carbon dioxide (CO2) and methane (CH4) from eruptions, contact metamorphism, and melting (dissociation) of gas hydrates; b) their deadly effects, including marine anoxia and thermal stress; c) increasingly sophisticated paleotemperature proxies (e.g. δ18O of shell material) through case studies of the best-known LIP-warming-extinction nexi; and d) global warming through the lens of the putative “Anthropocene” extinction

Sperm motility and fertilisation success in an acidified and hypoxic environment

The distribution and function of many marine species is largely determined by the effect of abiotic drivers on their reproduction and early development, including those drivers associated with elevated CO2 and global climate change. A number of studies have therefore investigated the effects of elevated pCO2 on a range of reproductive parameters, including sperm motility and fertilisation success. To date, most of these studies have not examined the possible synergistic effects of other abiotic drivers, such as the increased frequency of hypoxic events that are also associated with climate change. The present study is therefore novel in assessing the impact that a hypoxic event could have on reproduction in a future high CO2 ocean. Specifically, this study assesses sperm motility and fertilisation success in the sea urchin Paracentrotus lividus exposed to elevated pCO2 for 6 months. Gametes extracted from these pre acclimated individuals were subjected to hypoxic conditions simulating an hypoxic event in a future high CO2 ocean. Sperm swimming speed increased under elevated pCO2 and decrease under hypoxic conditions resulting in the elevated pCO2 and hypoxic treatment being approximately equivalent to the control. There was also a combined negative effect of increased pCO2 and hypoxia on the percentage of motile sperm. There was a significant negative effect of elevated pCO2 on fertilisation success, and when combined with a simulated hypoxic event there was an even greater effect. This could potentially affect cohort recruitment and in turn reduce the density of this ecologically and economically important ecosystem engineer therefore potentially effecting biodiversity and ecosystem services

Native and exotic oysters in Brazil: comparative tolerance to hypercapnia

Environmental hypercapnia in shallow coastal marine ecosystems can be exacerbated by increasing levels of atmospheric CO2. In these ecosystems organisms are expected to become increasingly subjected to pCO2 levels several times higher than those inhabiting ocean waters (e.g.: 10,000 µatm), but still our current understanding on different species capacity to respond to such levels of hypercapnia is limited. Oysters are among the most important foundation species inhabiting these coastal ecosystems, although natural oyster banks are increasingly threatened worldwide. In the present study we studied the effects of hypercapnia on two important oyster species, the pacific oyster C. gigas and the mangrove oyster C. brasiliana, to bring new insights on different species response mechanisms towards three hypercapnic levels (ca. 1,000; 4,000; 10,000 µatm), by study of a set of biomarkers related to metabolic potential (electron transport system - ETS), antioxidant capacity (SOD, CAT, GSH), cellular damage (LPO) and energetic fitness (GLY), in two life stages (juvenile and adult) after 28 days of exposure. Results showed marked differences between each species tolerance capacity to hypercapnia, with contrasting metabolic readjustment strategies (ETS), different antioxidant response capacities (SOD, CAT, GSH), which generally allowed to prevent increased cellular damage (LPO) and energetic impairment (GLY) in both species. Juveniles were more responsive to hypercapnia stress in both congeners, and are likely to be most sensitive to extreme hypercapnia in the environment. Juvenile C. gigas presented more pronounced biochemical alterations at intermediate hypercapnia (4,000 µatm) than C. brasiliana. Adult C. gigas showed biochemical alterations mostly in response to high hypercapnia (10,000 µatm), while adult C. brasiliana were less responsive to this environmental stressor, despite presenting decreased metabolic potential. Our data bring new insights on the biochemical performance of two important oyster species, and suggest that the duration of extreme hypercapnia events in the ecosystem may pose increased challenges for these organisms as their tolerance capacity may be time limited.publishe

Contributions of scale: What we stand to gain from Indigenous and local inclusion in climate-health monitoring and surveillance systems

Understanding how climate change will affect global health is a defining challenge this century. This is predicated, however, on our ability to combine climate and health data to investigate the ways in which variations in climate, weather, and health outcomes interact. There is growing evidence to support the value of place- and community-based monitoring and surveillance efforts, which can contribute to improving both the quality and equity of data collection needed to investigate and understand the impacts of climate change on health. The inclusion of multiple and diverse knowledge systems in climate-health surveillance presents many benefits, as well as challenges. We conducted a systematic review, synthesis, and confidence assessment of the published literature on integrated monitoring and surveillance systems for climate change and public health. We examined the inclusion of diverse knowledge systems in climate-health literature, focusing on: 1) analytical framing of integrated monitoring and surveillance system processes 2) key contributions of Indigenous knowledge and local knowledge systems to integrated monitoring and surveillance systems processes; and 3) patterns of inclusion within these processes. In total, 24 studies met the inclusion criteria and were included for data extraction, appraisal, and analysis. Our findings indicate that the inclusion of diverse knowledge systems contributes to integrated climate-health monitoring and surveillance systems across multiple processes of detection, attribution, and action. These contributions include: the definition of meaningful problems; the collection of more responsive data; the reduction of selection and source biases; the processing and interpretation of more comprehensive datasets; the reduction of scale dependent biases; the development of multi-scale policy; long-term future planning; immediate decision making and prioritization of key issues; as well as creating effective knowledge-information-action pathways. The value of our findings and this review is to demonstrate how neither scientific, Indigenous, nor local knowledge systems alone will be able to contribute the breadth and depth of information necessary to detect, attribute, and inform action along these pathways of climate-health impact. Rather, it is the divergence or discordance between the methodologies and evidences of different knowledge systems that can contribute uniquely to this understanding. We critically discuss the possibility of what we, mainly local communities and experts, stand to lose if these processes of inclusion are not equitable. We explore how to shift the existing patterns of inclusion into balance by ensuring the equity of contributions and justice of inclusion in these integrated monitoring and surveillance system processes

The most primitive metazoan animals, the placozoans, show high sensitivity to increasing ocean temperatures and acidities

The increase in atmospheric carbon dioxide (CO2) leads to rising temperatures and acidification in the oceans, which directly or indirectly affects all marine organisms, from bacteria to animals. We here ask whether the simplest-and possibly also the oldest-metazoan animals, the placozoans, are particularly sensitive to ocean warming and acidification. Placozoans are found in all warm and temperate oceans and are soft-bodied, microscopic invertebrates lacking any calcified structures, organs, or symmetry. We here show that placozoans respond highly sensitive to temperature and acidity stress. The data reveal differential responses in different placozoan lineages and encourage efforts to develop placozoans as a potential biomarker system

Natural swimming speed of Dascyllus reticulatus increases with water temperature

Recent research on the relationship between coral reef water temperature and fish swimming activity has stated that swimming speed is inversely correlated with temperature above a species’ optimum temperature (Johansen, J. L., and Jones, G. P. 2011. Increasing ocean temperature reduces the metabolic performance and swimming ability of coral reef damselfishes. Global Change Biology, 17: 2971–2979; Johansen, J. L.,Messmer,V., Coker, D. J., Hoey, A. S., and Pratchett, M. S. 2014. Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish. Global Change Biology, 20: 1067–1074). For tropical coral reefs, one anticipated consequence of global warming is an increase of ≥38C in average water temperature in addition to greater thermal fluctuations [IPCC (Intergovernmental Panel on Climate Change). 2007. Summary for policymakers. In Climate Change 2007: The Physical Science Basis. Contribution of Working, Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Ed. by S. Solomon, D. Qin, and M. Manning et al. Cambridge University Press, Cambridge, UK; Lough, J. 2007. Climate and climate change on the Great Barrier Reef. In Climate Change and the Great Barrier Reef. Ed. by J. Johnson and P. A. Marshall, pp. 15–50. Great Barrier Reef Marine Park Authority and Australian Greenhouse Office, Townsville, Qld, Australia; Johansen and Jones, 2011]. Evaluating the behaviour of coral reef associated fish species at different temperatures can help to assess their sensitivity to climate change. In this study, the speed of freely swimming fish in a natural setting is investigated as a function of seasonal changes in water temperature, as contrasted with systematic temperature increases in a fish tank.Weshowthat Dascyllus reticulatusswim faster as a function of increased water temperature over the range 20.9–30.38C. The experiments were carried out using 3.6 million fish trajectories observed at the Kenting National Park in Taiwan. Fish speed was computed by detecting and tracking the fish through consecutive video frames, then converting image speeds to scene speeds. Temperatureswere grouped into 10 intervals. The data reveal an2 mms21 increase in average speed per additional temperature degree over the range of 20.9–30.38C. The Mann–Kendall test using the mean and median speed for each interval revealed that there is a speed increase trend as temperature increases at the 0.05 significance level, rather than a random increase. Our results complement previous studies that investigated the effect of temperature on the swimming performance of different fish species in the laboratory (Johansen and Jones, 2011; Myrick, C. A. and Cech, J. J. 2000. Swimming performance of four California stream fishes: temperature effects. Environmental Biology of Fishes, 58: 289–295; Ojanguren, A. F. and Bran ̃a, F. 2000. Thermal dependence of swimming endurance in juvenile brown trout. Journal of Fish Biology, 56: 1342–1347; Lough 2007; Johansen et al., 2014)

Non-native marine species in north-west Europe:Developing an approach to assess future spread using regional downscaled climate projections

1. Climate change can affect the survival, colonization and establishment of non-native species. Many non-native species common in Europe are spreading northwards as seawater temperatures increase. The similarity of climatic conditions between source and recipient areas is assumed to influence the establishment of such species, however, in a changing climate those conditions are difficult to predict. 2. A risk assessment methodology has been applied to identify non-native species with proven invasive qualities that have not yet arrived in north-west Europe, but which could become problematic in the future. Those species with the highest potential to become established or be problematic have been taken forward, as well as some that may be economically beneficial, for species distribution modelling to determine future potential habitat distributions under projected climate change. 3. In the past, species distribution models have usually made use of low resolution global environmental datasets. Here, to increase the local resolution of the distribution models, downscaled shelf seas climate change model outputs for north-west Europe were nested within global outputs. In this way the distribution model could be trained using the global species presence data including the species' native locations, and then projected using more comprehensive shelf seas data to understand habitat suitability in a potential recipient area. 4. Distribution modelling found that habitat suitability will generally increase further north for those species with the highest potential to become established or problematic. Most of these are known to be species with potentially serious consequences for conservation. With caution, a small number of species may present an opportunity for the fishing industry or aquaculture. The ability to provide potential future distributions could be valuable in prioritizing species for monitoring or eradication programmes, increasing the chances of identifying problem species early. This is particularly important for vulnerable infrastructure or protected or threatened ecosystems