Top PDF Ocean acidification increases the sensitivity of and variability in physiological responses of an intertidal limpet to thermal stress

Ocean acidification increases the sensitivity of and variability in physiological responses of an intertidal limpet to thermal stress

Ocean acidification increases the sensitivity of and variability in physiological responses of an intertidal limpet to thermal stress

Analysis of heart rate showed significantly higher temper- ature coefficients (Q 10 rates) for limpets at 20 ◦ C than at 24 ◦ C and post-acclimation thermal sensitivity of limpets at 400 ppm was lower than at 1000 ppm. Expression of hsp70 linearly increased with the increasing heat-shock tempera- tures, with the largest slope occurring in limpets acclimated under a future scenario (24 ◦ C and 1000 ppm pCO 2 ). These results suggested that limpets showed increased sensitivity and stress response under future conditions. Furthermore, the increased variation in physiological response under the future scenario indicated that some individuals have higher physio- logical plasticity to cope with these conditions. While short- term acclimation to reduced pH seawater decreases the abil- ity of partial individuals against thermal stress, physiological plasticity and variability seem to be crucial in allowing some intertidal animals to survive in a rapidly changing environ- ment.
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Temperature and acidification variability reduce physiological performance in the intertidal zone porcelain crab Petrolisthes cinctipes

Temperature and acidification variability reduce physiological performance in the intertidal zone porcelain crab Petrolisthes cinctipes

The Journal of Experimental Biology ABSTRACT We show here that increased variability of temperature and pH synergistically negatively affects the energetics of intertidal zone crabs. Under future climate scenarios, coastal ecosystems are projected to have increased extremes of low tide-associated thermal stress and ocean acidification-associated low pH, the individual or interactive effects of which have yet to be determined. To characterize energetic consequences of exposure to increased variability of pH and temperature, we exposed porcelain crabs, Petrolisthes cinctipes, to conditions that simulated current and future intertidal zone thermal and pH environments. During the daily low tide, specimens were exposed to no, moderate or extreme heating, and during the daily high tide experienced no, moderate or extreme acidification.
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The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

The role of stochastic thermal environments in modulating the thermal physiology of an intertidal limpet, Lottia digitalis

better understand energy availability, and antioxidant and oxidative stress levels to give insight into cellular defense mechanisms available immediately prior to a midday low tide period. We hypothesized that a stochastic tidal regime would increase protective mechanisms that would provide limpets with reduced temperature sensitivity and higher upper temperature tolerance. We predicted that L. digitalis acclimated to stochastic tidal regimes would be less sensitive and have a higher tolerance to heat stress than limpets exposed to predictable temperatures. The variability in the magnitude of temperature increase during periods of emersion would prime the limpets to maintain protective mechanisms when exposed to the highest temperatures; however, emersion periods with low to moderate increases in temperature would provide limpets with reprieve from consistently high low-tide temperatures, which could minimize accumulated damage from heat stress and improve efficiency in the recruiting of protective mechanisms (Hofmann and Somero, 1996; Gracey et al., 2008; Denny et al., 2011; Zhang et al., 2014; Huang et al., 2015).
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Inter-population thermal variability and physiological response in the intertidal fish Scartichthys viridis (Blenniidae)

Inter-population thermal variability and physiological response in the intertidal fish Scartichthys viridis (Blenniidae)

* e-mail for correspondence: pojeda@bio.puc.cl ABSTRACT Determining habitat conditions that generate individual physiological variability represents key basic knowledge to understand the direction of animal’s responses to habitat change. The coastal fish Scartichthys viridis inhabits low intertidal pools along the Chilean coast. Because seawater in the low intertidal is renewed during every tidal cycle, this zone is characterized by a low thermal variation and abundant food within and between localities. We evaluated whether seawater thermal conditions and food availability of low intertidal pools registered in three localities of Chilean coast are sufficient to generate physiological and energetic differences in individuals of S. viridis captured from three geographic separate populations spanning approximately 1,200 km. Southern fishes acclimatized to 25 ºC showed higher metabolic rates than those from other localities and thermal treatments. On the other hand, southern fishes in natural conditions showed higher condition factor than northern fishes. This evidence is sufficient to indicate that slight latitudinal differences in tidepool seawater temperature associated to differential food availability induced an energetic constraint in this species. Moreover, southern population of S. viridis may suffer important effects on energetic allocation if seawater temperature increases slightly, with repercussions on its geographic distribution in southern Pacific Ocean.
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Biochemical adaptation to ocean acidification

Biochemical adaptation to ocean acidification

Intraspecific comparisons between individuals from different habitats allow inferences to be drawn about the plasticity of the physiological responses organisms may have to OA. Local adaptation and differential selection of specific genotypes under acidified conditions has been shown to govern allele frequency of top candidate genes for OA responses (Pespeni et al., 2013). Purple urchin larvae (Strongylocentrotus purpuratus) locally adapted to less-acidic sites show this increase in allele frequency when exposed to pH stress, indicating that the adaptive capacity may be a result of standing genetic variation across the spatial-temporal habitats (Pespeni et al., 2013). Intraspecific comparisons with differing thermal habitats show how thermal plasticity can shape responses to pH stress. Populations of intertidal Concholepas concholepas snails from warmer habitats increase their aerobic capacity, resulting in higher levels of molecular chaperones when exposed to pH stress (Lardies et al., 2014). These responses are indicative of how thermal plasticity across populations can govern the tolerance limits of acidification stress, possibly by inducing similar pathways.
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In situ behavioural and physiological responses of Antarctic microphytobenthos to ocean acidification

In situ behavioural and physiological responses of Antarctic microphytobenthos to ocean acidification

Microalgae play a vital role in ecosystem functioning 16,21 , especially in the MPB in Antarctic benthic ecosys- tems, which in low-light habitats under sea ice are the dominant autotroph in the absence of macro algae 27,28 . Microalgae form the basis of many marine food webs and perform key ecological roles in fixing carbon, recycling nutrients, stabilising sediments and contribute to modifying global climates via their role in the carbon cycle 28,29 . While the uptake of carbon by microalgae is essential for their photosynthesis, it is also intrinsically linked to ocean carbon cycling and will interact with OA 23,30–32 . Microalgae have a number of ecologically linked processes that may be altered by OA. For example, MPB photosynthetic yield, primary production and net production drive vital ecosystem services in soft sediment communities, which if altered will have flow on effects to the whole community 33 . Changes to these ecosystem services will be positive or negative dependent largely on whether conditions are more or less preferential for microalgae 34 .
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Assessing the physiological responses of the gastropod Crepidula fornicata to predicted ocean acidification and warming

Assessing the physiological responses of the gastropod Crepidula fornicata to predicted ocean acidification and warming

respiration, ammonia excretion, filtration and calcification on small and large individuals.. 35.[r]

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Genetic and morpho-physiological differentiation in a limpet population across an intertidal gradient

Genetic and morpho-physiological differentiation in a limpet population across an intertidal gradient

This pattern was accompanied by morpho-physiological variations: the upper shore had fewer small limpets, lower shell shape dispersion (with a morphotype characterized by a higher shell), and less water loss and mortality related to air exposure than the lower shore. The results reported herein support the idea that the extreme and unpredict- able conditions of the upper shore may impose strong selection pressure on its inhabitants, leading to considerable morpho-physiological differentiation consistent with different genetic composition. This probably plays an important role in structuring the spatial distribution of natural S. lessonii populations with a possible effect on size-structure distribution.
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Plastic responses of bryozoans to ocean acidification

Plastic responses of bryozoans to ocean acidification

Colonies raised under high CO 2 grew more quickly, investing less in reproduction and producing lighter skeletons when compared with genetically identical clones raised under current surface atmosphere CO 2 values. Bryozoans held under high CO 2 conditions also changed the Mg/Ca ratio of skeletal calcite and increased the expression of organic coverings in new growth, which may serve as protection against acidified water. We also observed strong differences between source populations in reproductive investment and organic covering reaction norms, consistent with adaptive responses to persistent spatial variation in local oceanographic conditions. Our results demonstrate that phenotypic plasticity and energetic trade-offs can mediate biological responses to global environmental change, and highlight the broad range of strategies available to colonial organisms.
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Zooplankton community responses to Ocean Acidification

Zooplankton community responses to Ocean Acidification

same time they promote settlement of planulae (Ishii et al. 2008), favour polyps’ asexual reproduction (Ishii et al. 2008), and reduce predation pressure during polyp development (Ishii and Katsukoshi 2010; Miller and Graham 2012). In contrast, the knowledge on the ephyral stage of Aurelia sp. is still limited. Survivorship of Aurelia sp. ephyrae is low; less than 1 % survive to reach adulthood, but the causes of this high mortality remain elusive (Ishii et al. 2004). According to Fu and colleagues (2014) ephyra cumulative mortality in the field can reach ~95 % by age 4.6 days and increase further to ~99 % by the young medusa stage (20 to 28 day old). We are aware of only a few studies dealing with the effects of temperature on development and survival of ephyrae demonstrating that low temperatures lead to decreased feeding rates (e.g. Widmer 2005; Wang and Li 2015). Previous studies on Aurelia labiata indicate that the number of statoliths in ephyrae released at 7.2 pH-treatments did not differ but had significantly smaller volumes compared to higher pH-levels (7.5 and 7.9) (Winans and Purcell 2010). This could potentially affect orientation and swimming activities of the free-swimming stages (ephyrae and medusae). However, acids (HCl) and bases (NaOH) were added to the experimental treatments in this study on A. labiata which may not sufficiently reflect the seawater carbonate chemistry changes associated with ocean acidification (Gattuso and Lavigne 2009; Klein et al. 2014). The effects of hypoxia on ephyrae are unknown but also may reduce swimming activity and increase mortality due to negative effects on metabolic processes. Nonetheless, the potential interactive effects of these stressors could produce different, potentially more severe effects and thus provide a more realistic understanding of this species in a changing ocean context. Thus, there is a great need to fill this gap in our knowledge, especially investigating these stressors in concert.
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Physiological and biochemical responses of Emiliania huxleyi to ocean acidification and warming are modulated by UV radiation

Physiological and biochemical responses of Emiliania huxleyi to ocean acidification and warming are modulated by UV radiation

4 Discussion Our results demonstrated that both photosynthesis and calci- fication were inhibited by UVB. In contrast, UVA was more inhibitory for photosynthesis than UVB, while it had a pos- itive effect on calcification. The degree to which UVA and UVB affected the performance of photosynthesis and calcifi- cation varied depending on CO 2 concentrations and temper- ature levels. Of the three temperature levels used, 15 ◦ C was much lower than the optimal growth temperature for both HC- and LC- grown cells. For LC cultures, the growth rate was the same at 20 and 24 ◦ C, and these two temperatures were in the optimal range for cell growth. While 20 ◦ C was very close to the optimal temperature for HC-grown cells, the growth rate at 24 ◦ C was significantly reduced, suggesting that the cell growth at this temperature may already be ther- mally inhibited. The different growth state among the three temperature levels, particularly that between HC- and LC- grown cells at the highest temperature, potentially affected the photosynthetic and calcification responses to UV radia- tion.
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Impacts of ocean acidification on intertidal benthic foraminiferal growth and calcification

Impacts of ocean acidification on intertidal benthic foraminiferal growth and calcification

‡ These authors also contributed equally to this work. * wena@st-andrews.ac.uk Abstract Foraminifera are expected to be particularly susceptible to future changes in ocean carbon- ate chemistry as a function of increased atmospheric CO 2 . Studies in an experimental recir- culating seawater system were performed with a dominant benthic foraminiferal species collected from intertidal mudflats. We investigated the experimental impacts of ocean acidifi- cation on survival, growth/calcification, morphology and the biometric features of a calcare- ous species Elphidium williamsoni. Foraminifera were exposed for 6 weeks to four different pH treatments that replicated future scenarios of a high CO 2 atmosphere resulting in lower seawater pH. Results revealed that declining seawater pH caused a decline in foraminiferal survival rate and growth/calcification (mainly through test weight reduction). Scanning elec- tron microscopy image analysis of live specimens at the end of the experimental period show changes in foraminiferal morphology with clear signs of corrosion and cracking on the test surface, septal bridges, sutures and feeding structures of specimens exposed to the lowest pH conditions. These findings suggest that the morphological changes observed in shell feeding structures may serve to alter: (1) foraminiferal feeding efficiency and their long-term ecological competitiveness, (2) the energy transferred within the benthic food web with a subsequent shift in benthic community structures and (3) carbon cycling and total CaCO 3 production, both highly significant processes in coastal waters. These experimental results open-up the possibility of modelling future impacts of ocean acidification on both cal- cification and dissolution in benthic foraminifera within mid-latitude intertidal environments, with potential implications for understanding the changing marine carbon cycle.
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Diurnally fluctuating pCO(2) modifies the physiological responses of coral recruits under ocean acidification

Diurnally fluctuating pCO(2) modifies the physiological responses of coral recruits under ocean acidification

OA. Together, although the photochemical performance was enhanced by the fluctuating OA treatment, it was unable to fully compensate for the increased energy expense for coral recruits. More importantly, in the fluctuating OA treatment, corals appeared to compromise asexual reproduction and ROS detoxification to sustain skeletal growth, indicating potential trade-offs between calcification and other key physiological processes. These findings suggest that diurnal variability in pH/carbonate chemistry is likely to be an overriding factor influencing and determining the early success and recruitment of corals under future OA. Our study also highlights the importance of considering a broader spectrum of physiological traits in order to accurately and fully characterize the overall change in fitness and the possible trade-offs between different physiological functions when addressing corals’ responses to environmental stress.
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Regional adaptation defines sensitivity to future ocean acidification

Regional adaptation defines sensitivity to future ocean acidification

Discussion Together, the findings of this study suggest that the relative sensitivity of different populations of L. littorea to future OA are likely to vary considerably across its geographical range of extension in the Northeast Atlantic through local and regional adaptation, with populations closer to the range edges being most sensitive. If OA selects against these sensitive, range-edge genotypes, it could cause a reduction of genetic diversity levels that could have far- reaching consequences for the ability of these populations to respond and further adapt to other local and global stressors. As a consequence, with increased OA, we may predict a further shift and possible reduction in the geographical range of L. littorea, as genotypes closer to the range edge appear at greater risk of extinction based on their specific metabolic abilities 36 . These genotypes could be replaced by central population genotypes, particularly towards the northern edge where snails appear to be metabolically less competent to deal with OA. Furthermore, the negative relationship between seawater pH and latitude 37 may mean that southern genotypes would require to migrate southward in order to compensate for the negative effects of OA 8 , although this seems unlikely given the negative impact of global warming that has already caused a northward migration of L. littorea populations at this species’ southern range edge 38 . In general, the negative effects of OA on L. littorea, a keystone species in rocky intertidal habitats, may have negative repercussions on the structure, dynamics and functioning of intertidal communities and ecosystems across the North Atlantic 39,40 , particularly towards the range edges of its distribution.
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Ocean acidification

Ocean acidification

1. The variability observed in carbonate chemistry in UK coastal waters needs to be much better understood, requir- ing continuation of existing ocean acidification time series, the measurement of other parameters, dedicated effort on data interpretation and the further development of guide- lines for cost-effective and integrated biogeochemical moni- toring to meet national and international policy needs. The linkage between river water quality, carbonate chemistry in estuaries and coastal ocean acidification is a specific aspect that has been neglected, and warrants further attention 2. The validity and applicability of laboratory-based impact studies need to be re-visited in the context of the observed natural variability in environmental conditions. Free ocean CO 2 enrichment (FOCE) techniques should be developed and used for in situ experiments; e.g. on cold-water corals.
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Major cellular and physiological impacts of ocean acidification on a reef building coral

Major cellular and physiological impacts of ocean acidification on a reef building coral

Abstract 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.
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Effects of ocean acidification on early life history stages of the intertidal porcelain crab Petrolisthes cinctipes

Effects of ocean acidification on early life history stages of the intertidal porcelain crab Petrolisthes cinctipes

Crim et al., 2011; Findlay et al., 2009; Walther et al., 2010). The persistence or failure of a population will be determined by the SUMMARY Intertidal zone organisms naturally experience daily fluctuations in pH, presently reaching values beyond what is predicted for open ocean surface waters from ocean acidification (OA) by the year 2100, and thus present an opportunity to study the pH sensitivity of organisms that are presumably adapted to an acidified environment. The intertidal zone porcelain crab, Petrolisthes cinctipes, was used to study physiological responses to low pH in embryonic, larval and newly recruited juvenile life-history stages. In these crabs, embryonic development occurs in the pH-variable intertidal zone (pH  6.9–9.5), larvae mature in the more stable pelagic environment (pH  7.9–8.2), and juvenile crabs settle back into the pH-variable intertidal zone. We examined survival, cardiac performance, energetics and morphology in embryonic, larval and juvenile crabs exposed to two pH conditions (pH  7.9 and 7.6). Embryos and larvae were split by brood between the pH treatments for 9  days to examine brood-specific responses to low pH. Hatching success did not differ between pH conditions, but ranged from 30% to 95% among broods. Larval survival was not affected by acidification, but juvenile survival was reduced by ~30% after longer (40  days) exposure to low pH. Embryonic and larval heart rates were 37% and 20% lower at low pH, and there was a brood-specific response in embryos. Embryos did not increase in volume under acidified conditions, compared with a 15% increase in ambient conditions. We conclude that sustained exposure to low pH could be detrimental to P. cinctipes embryos and larvae despite the fact that embryos are regularly exposed to naturally fluctuating hypercapnic water in the intertidal zone. Importantly, our results indicate that early life-history stage responses to OA may be brood specific through as yet undetermined mechanisms.
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Intraspecific variation in physiological performance of a benthic elasmobranch challenged by ocean acidification and warming

Intraspecific variation in physiological performance of a benthic elasmobranch challenged by ocean acidification and warming

ABSTRACT Elucidating the combined effects of increasing temperature and ocean acidification on performance of fishes is central to our understanding of how species will respond to global climate change. Measuring the metabolic costs associated with intense and short activities, such as those required to escape predators, is key to quantifying changes in performance and estimating the potential effects of environmental stressors on survival. In this study, juvenile little skate Leucoraja erinacea from two neighboring locations (Gulf of Maine, or northern location, and Georges Bank, or southern location) were developmentally acclimatized and reared at current and projected temperatures (15, 18 or 20°C) and acidification conditions ( pH 8.1 or 7.7), and their escape performance was tested by employing a chasing protocol. The results from this study suggest countergradient variation in growth between skates from the two locations, while the optimum for escape performance was at a lower temperature in individuals from the northern latitudes, which could be related to adaptation to the local thermal environment. Aerobic performance and scope declined in skates from the northern latitudes under simulated ocean warming and acidification conditions. Overall, the southern skates showed lower sensitivity to these climatic stressors.
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Impacts of Ocean Acidification

Impacts of Ocean Acidification

A better understood consequence of ocean acidifica- tion is the reduction of calcium carbonate precipitation by shells of marine organisms, including commercially valuable shellfish, crustaceans and corals. The eco- nomic value of coral reefs is primarily linked to their function as a habitat and nursery for commercial fish stocks, acting as a natural barrier for coastlines, and for the provision of recreation and tourism opportuni- ties. Assuming a conservative value 23 of $100 000/km 2 / yr, the global economic value associated with reefs is in the order of $30 billion/yr. Since ocean acidification is expected to impact a major part of these reefs within this century, it is plausible that the loss of coral reefs will amount to a loss of tens of billions of dollars per year. The economic value of damage to coral reefs due to ocean acidification has recently been estimated for the first time 24 and losses were found to be of the order of 0.18% of global GDP in 2100. This is one order of magnitude smaller than the estimated impact of climate change but still represents a substantial economic loss. Further research is required to refine these damage estimates and to extend the scope of analysis beyond coral reefs to other potentially impacted marine resources. Similarly, a recent case study of the evolution of US commercial fishery rev- enues, focusing especially on mollusks, indicated that substantial revenue declines, job losses, and indirect economic costs may occur due to ocean acidification, and proposed possible adaptation strategies designed to support fisheries and marine-resource-dependent communities, many of which already possess little economic resilience. 25
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The Risk of Ocean Acidification to Ocean Ecosystems

The Risk of Ocean Acidification to Ocean Ecosystems

To understand what marine ecosystems may look like in the future if carbon emissions continue unabated, it is necessary to know the severity of the perturbation that different ecosystems will be exposed to and their ability to adapt within the time-scales of change. The severity and speed of ocean acidification, the exposure and vulnerability of the component organisms of an ecosystem to ocean acidification and their role in an ecosystem contribute to the risk of impacts to ecosystem structure and function. Although there are great uncertainties moving from impacts on individual organisms to impacts on complex marine ecosystems, these basic changes to marine chemistry pose a substantial risk to marine ecosystem structure and function through the impacts on the growth, physiology, behaviour, predator-prey interactions, competitiveness and population dynamics of individual species and how these may cascade through the rest of the ecosystem. Some organisms are able to adapt to ocean acidification, especially if food resources are high, by trading-off energy from one physiological function to another, although this may impact their long-term survival and ecosystem function.
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