Global meta‐analysis reveals the impacts of ocean warming and acidification on kelps

Atmospheric CO2 concentration [CO2] has increased from a pre-industrial level of approximately 280 ppm to approximately 385 ppm, with further increases (700–1000 ppm) anticipated by the end of the twenty-first century [[1][1]]. Over the past three decades, changes in [CO2] have increased global

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 473:235-246 (2013) - DOI: https://doi.org/10.3354/meps10058 Effects of ocean warming and acidification on embryos and non-calcifying larvae of the invasive sea star Patiriella regularis Maria Byrne1,*, Maria Gonzalez-Bernat2, Steve Doo3, Shawna Foo3, Natalie Soars3, Miles Lamare2 1Schools of Medical and Biological Sciences, University of Sydney, New South Wales 2006, Australia 2Department of Marine Science, University of Otago, Dunedin, New Zealand 3School of Medical Sciences, University of Sydney, New South Wales 2006, Australia *Email: mbyrne@anatomy.usyd.edu.au ABSTRACT: Little is known about the effects of potential synergies between concurrent ocean warming and acidification on marine benthos. We investigated the effects of warming and acidification on development to the non-calcifying larval stage in the sea star Patiriella regularis, in embryos reared from fertilization in present and future (2100+) conditions. Fertilization using gametes from multiple parents, to represent populations of spawners, was resilient to both stressors, as were cleavage stage embryos. Warming increased developmental rate across all pH levels. For blastulae, there was a complex interaction between stressors, with +4°C/pH 7.6 lethal to many embryos. A 4°C warming increased mortality by the gastrulation stage by 13 to 25% across all pH levels. In conjunction with warming, pH 7.6 increased mortality by 25 to 27% across all temperatures. For embryos that reached the 3 d bipinnaria stage, warming reduced the percentage of normal larvae and larval size, with no effect of acidification. These results highlight the importance of considering both warming and acidification, and effects on early embryos, in assessing life history responses to ocean change. Bipinnaria reared to Day 28 to determine the effects of acidification on non-calcifying feeding larvae provided a comparison with results for calcifying echinoplutei. pH 7.6 resulted in smaller larvae and increased mortality by 30%. After 24 d, near-future ocean acidification levels (pH 7.8) also resulted in smaller larvae. The effects of acidification in reducing growth in larvae that do not calcify indicates that the stunting response of echinoderm feeding larvae to pH/pCO2 is strongly influenced by hypercapnic changes in metabolism and teratogenic effects. The results have implications for P. regularis in its invasive range in Australia, where this species is likely to be deleteriously affected by ocean warming. KEY WORDS: Climate change · Ocean warming · Ocean acidification · Sea star · Non-calcifying larvae · Invasive species Full text in pdf format Supplementary material PreviousNextCite this article as: Byrne M, Gonzalez-Bernat M, Doo S, Foo S, Soars N, Lamare M (2013) Effects of ocean warming and acidification on embryos and non-calcifying larvae of the invasive sea star Patiriella regularis. Mar Ecol Prog Ser 473:235-246. https://doi.org/10.3354/meps10058 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 473. Online publication date: January 21, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod

Seagrass Thalassia hemprichii and associated bacteria co-response to the synergistic stress of ocean warming and ocean acidification

Physiology, behaviour and inter-species interactions of jellyfish under changing ocean conditions

Ocean warming and acidification alter calcification and innate immune system gene expression in juvenile American lobsters, Homarus americanus.

Ocean warming and acidification threaten the future growth of coral reefs. This is because the calcifying coral reef taxa that construct the calcium carbonate frameworks and cement the reef together are highly sensitive to ocean warming and acidification. However, the global-scale effects of ocean warming and acidification on rates of coral reef net carbonate production remain poorly constrained despite a wealth of studies assessing their effects on the calcification of individual organisms. Here, we present global estimates of projected future changes in coral reef net carbonate production under ocean warming and acidification. We apply a meta-analysis of responses of coral reef taxa calcification and bioerosion rates to predicted changes in coral cover driven by climate change to estimate the net carbonate production rates of 183 reefs worldwide by 2050 and 2100. We forecast mean global reef net carbonate production under representative concentration pathways (RCP) 2.6, 4.5, and 8.5 will decline by 76, 149, and 156%, respectively, by 2100. While 63% of reefs are projected to continue to accrete by 2100 under RCP2.6, 94% will be eroding by 2050 under RCP8.5, and no reefs will continue to accrete at rates matching projected sea level rise under RCP4.5 or 8.5 by 2100. Projected reduced coral cover due to bleaching events predominately drives these declines rather than the direct physiological impacts of ocean warming and acidification on calcification or bioerosion. Presently degraded reefs were also more sensitive in our analysis. These findings highlight the low likelihood that the world's coral reefs will maintain their functional roles without near-term stabilization of atmospheric CO2 emissions.

Coral reefs are hyperdiverse ecosystems that are highly threatened by ocean warming and acidification and are vital to the livelihoods of millions of people (Hoegh-Guldberg et al., 2007). Climate change refugia, habitats with favourable environmental conditions that species may retreat to during inhospitable climatic conditions, offer potential safe havens from anthropogenic climate change (Keppel et al., 2012). Such refugia are increasingly important for conservation planning in terrestrial ecosystems (Keppel et al., 2015). Cacciapaglia & van Woesik (2015) take an important step towards identifying refugia for coral reefs. However, their predictions are based on only one global stressor (ocean warming) and made at a coarse scale (>80 km2). As a result, their findings are overly positive and of limited predictive power regarding the identification of effective future refugia for coral reefs. Considering the serious impacts of ocean acidification (Hoegh-Guldberg et al., 2007), it cannot be ignored in predictive modelling of future coral reef refugia. These impacts will be most severe at higher latitudes, constraining the ability of corals to escape ocean warming through migration. As a result, it has been suggested that few or no refugia will be able to safeguard the long-term persistence of coral reefs (van Hooidonk et al., 2014). Furthermore, ocean acidification and warming will exacerbate local stressors related to water pollution, overexploitation and coral-limiting environments (Hoegh-Guldberg et al., 2007). While Cacciapaglia & van Woesik (2015) did consider local stressors to some extent by masking areas receiving high river outflow and areas experiencing cold temperatures, they did not consider global ocean acidification. Hence, their results are likely to be excessively positive regarding the number and size of future coral reef refugia. Scale is a key consideration for modelling species distributions under future climates (Keppel et al., 2012). Indeed, using excessively coarse scales for species distributions modelling will produce inaccurate projections (Franklin et al., 2013). For coral reefs, key environmental parameters affecting coral performance and responses to ongoing ocean acidification and warming, such as temperature and aragonite saturation, may vary among individual reefs within coral reef complexes and even within reefs (Manzello et al., 2012; Guadayol et al., 2014). Although Cacciapaglia & van Woesik (2015) used a finer resolution (~9.2 × 9.2 km) than a previous attempt (1 × 1 degree latitude/longitude, van Hooidonk et al., 2014), this resolution is not relevant to fine-scale microclimatic habitats that exist on coral reefs. Even parts of a single reef system could potentially provide important refugia. For example, the proximity to seagrass beds can provide considerable buffering from the effects of ocean acidification (Manzello et al., 2012). Therefore, to adequately predict the existence and location of coral reef refugia, relevant environmental data need to be downscaled to sufficiently fine scales. In marine environments, this is particularly complex, as environmental variables vary with horizontal distance and depth (Guadayol et al., 2014). Refugia are species specific (Stewart et al., 2010; Keppel et al., 2012), as species display varying responses to environmental conditions (Cacciapaglia & van Woesik, 2015). The selection of species for predictive modelling therefore will have considerable impact on the forecast refugia for coral reef communities. Laudably, Cacciapaglia & van Woesik (2015) used 12 coral species to determine their proposed refugia. However, all species selected were generalists, which generally have greater ranges, dispersal potentials, genetic diversity, adaptive potential and resilience to environmental changes than specialist species (see Cacciapaglia & van Woesik, 2015). These rare specialists are most at risk from anthropogenic climate change and will likely depend on local, fine-scale refugia for persistence (Purvis et al., 2000). Therefore, the responses of rare specialist species need to be taken into account, if effective refugia for coral reef communities are to be identified. The identification of refugia for coral reefs is likely to be important for safeguarding the persistence of these communities under anthropogenic climate change, and Cacciapaglia & van Woesik (2015) present an important first step towards this goal. However, their analyses are overly simplistic, and the inclusion of ocean acidification into the modelling would have likely produced vastly different results (see van Hooidonk et al., 2014). Ideally, modelling of future distributions of coral reef communities would include ocean acidification and warming and indicators of other key stressors at appropriate scales for a wide variety of species. However, our ability to do this is currently constrained by the unavailability of sufficient spatial data at fine scales for key environmental parameters, such as ocean temperature and aragonite saturation. It is therefore vitally important to gain an understanding of the variability of marine environmental parameters in three-dimensional spaces at appropriate scales, and to use realistic modelling approaches, if effective refugia for coral reef communities are to be identified.

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 562:101-111 (2016) - DOI: https://doi.org/10.3354/meps11944 Interactive effects of ocean warming and acidification on sperm motility and fertilization in the mussel Mytilus galloprovincialis Angela R. Eads*, W. Jason Kennington, Jonathan P. Evans Centre for Evolutionary Biology, University of Western Australia, Crawley, WA 6009, Australia *Corresponding author: angela.eads@graduate.uwa.edu.au ABSTRACT: Gametes of marine broadcast spawners are highly susceptible to the threats of ocean warming and acidification. Here, we explore the main and interacting effects of temperature and pH changes on sperm motility and fertilization rates in the mussel Mytilus galloprovincialis. Additionally, we determine how temperature and pH interact to influence the motility of aging sperm. We show that the interactive effects of temperature (18°C or 24°C) and pH (ranging from 7.6 to 8.0) on sperm motility depend on the time that sperm spend in these conditions. Specifically, sperm linearity was influenced by a temperature × pH interaction when measured after a relatively short exposure to the treatment conditions, while main effects of temperature and pH (but no interaction) on sperm motility became apparent only after prolonged exposure (2 h) to the treatments. Despite the interactive effects of temperature and pH on sperm motility, these factors had independent effects on fertilization rates, which were significantly higher at the ambient ocean pH level and at the elevated temperature. This study highlights the importance of considering the combined effects of predicted ocean changes on sperm motility and fertilization rates, and cautions against using only sperm motility as a proxy for reproductive fitness. Detrimental effects of pH and temperature may only be uncovered when these factors are examined together, or conversely, negative impacts of one variable may be buffered by changes in another. Our results raise the intriguing possibility that some species may cope better with ocean acidification if they simultaneously experience ocean warming. KEY WORDS: Ocean acidification · Ocean warming · Sperm motility · Fertilization · Broadcast spawner Full text in pdf format Supplementary material PreviousNextCite this article as: Eads AR, Kennington WJ, Evans JP (2016) Interactive effects of ocean warming and acidification on sperm motility and fertilization in the mussel Mytilus galloprovincialis. Mar Ecol Prog Ser 562:101-111. https://doi.org/10.3354/meps11944 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 562. Online publication date: December 29, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Boosted nutritional quality of food by CO2 enrichment fails to offset energy demand of herbivores under ocean warming, causing energy depletion and mortality

Biological communities are shaped by complex interactions between organisms and their environment as well as interactions with other species. Humans are rapidly changing the marine environment through increasing greenhouse gas emissions, resulting in ocean warming and acidification. The first response by animals to environmental change is predominantly through modification of their behaviour, which in turn affects species interactions and ecological processes. Yet, many climate change studies ignore animal behaviour. Furthermore, our current knowledge of how global change alters animal behaviour is mostly restricted to single species, life phases and stressors, leading to an incomplete view of how coinciding climate stressors can affect the ecological interactions that structure biological communities. Here, we first review studies on the effects of warming and acidification on the behaviour of marine animals. We demonstrate how pervasive the effects of global change are on a wide range of critical behaviours that determine the persistence of species and their success in ecological communities. We then evaluate several approaches to studying the ecological effects of warming and acidification, and identify knowledge gaps that need to be filled, to better understand how global change will affect marine populations and communities through altered animal behaviours. Our review provides a synthesis of the far-reaching consequences that behavioural changes could have for marine ecosystems in a rapidly changing environment. Without considering the pervasive effects of climate change on animal behaviour we will limit our ability to forecast the impacts of ocean change and provide insights that can aid management strategies.

Ocean warming is altering the biogeographical distribution of marine organisms. In the tropics, rising sea surface temperatures are restructuring coral reef communities with sensitive species being lost. At the biogeographical divide between temperate and tropical communities, warming is causing macroalgal forest loss and the spread of tropical corals, fishes and other species, termed "tropicalization". A lack of field research into the combined effects of warming and ocean acidification means there is a gap in our ability to understand and plan for changes in coastal ecosystems. Here, we focus on the tropicalization trajectory of temperate marine ecosystems becoming coral-dominated systems. We conducted field surveys and in situ transplants at natural analogues for present and future conditions under (i) ocean warming and (ii) both ocean warming and acidification at a transition zone between kelp and coral-dominated ecosystems. We show that increased herbivory by warm-water fishes exacerbates kelp forest loss and that ocean acidification negates any benefits of warming for range extending tropical corals growth and physiology at temperate latitudes. Our data show that, as the combined effects of ocean acidification and warming ratchet up, marine coastal ecosystems lose kelp forests but do not gain scleractinian corals. Ocean acidification plus warming leads to overall habitat loss and a shift to simple turf-dominated ecosystems, rather than the complex coral-dominated tropicalized systems often seen with warming alone. Simplification of marine habitats by increased CO2 levels cascades through the ecosystem and could have severe consequences for the provision of goods and services.

The Antarctic Peninsula is one of the fastest-warming places on Earth. Elevated sea water temperatures cause glacier and sea ice melting. When icebergs melt into the ocean, it “freshens” the saltwater around them, reducing its salinity. The oceans absorb excess anthropogenic carbon dioxide (CO2) causing decline in ocean pH, a process known as ocean acidification. Many marine organisms are specifically affected by ocean warming, freshening and acidification. Due to the sensitivity of Antarctica to global warming, using biomarkers is the best way for scientists to predict more accurately future climate change and provide useful information or ecological risk assessments. The 70-kilodalton (kDa) heat shock protein (HSP70) chaperones have been used as biomarkers of stress in temperate and tropical environments. The induction of the HSP70 genes (Hsp70) that alter intracellular proteins in living organisms is a signal triggered by environmental temperature changes. Induction of Hsp70 has been observed both in eukaryotes and in prokaryotes as response to environmental stressors including increased and decreased temperature, salinity, pH and the combined effects of changes in temperature, acidification and salinity stress. Generally, HSP70s play critical roles in numerous complex processes of metabolism; their synthesis can usually be increased or decreased during stressful conditions. However, there is a question as to whether HSP70s may serve as excellent biomarkers in the Antarctic considering the long residence time of Antarctic organisms in a cold polar environment which appears to have greatly modified the response of heat responding transcriptional systems. This review provides insight into the vital roles of HSP70 that make them ideal candidates as biomarkers for identifying resistance and resilience in response to abiotic stressors associated with climate change, which are the effects of ocean warming, freshening and acidification in Antarctic organisms.

Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

Impact of near-future ocean warming and acidification on the larval development of coral-eating starfish Acanthaster cf. solaris after parental exposure