Effects Of pCO2 Research Articles

Increased irradiance availability mitigates the physiological performance of species of the calcifying green macroalga Halimeda in response to ocean acidification

Although negative responses of tropical calcifying organisms to ocean acidification have been widely reported, the modulating potential of irradiance combined with elevated pCO2 has not been well studied. In this study, the interactive effects of elevated pCO2 and irradiance availability on the physiology of calcifying macroalgae Halimeda cylindracea and Halimeda lacunalis were investigated using a fully factorial, 28-day aquaria coupling experiment. The results of the present study demonstrate that elevated pCO2 negatively influences growth, photosynthesis, calcification and other physiological processes of both Halimeda species. However, these negative effects could be mitigated to some extent by increased irradiance availability. Specific growth rate (SGR), net calcification rates (Gnet) and maximum quantum yield (Fv/Fm) decreased significantly by 6.84%–86.70%, 51.78%–62.29% and 2.37%–28.91% in elevated pCO2 treatments. However, SGR, Gnet and Fv/Fm increased by 3.39%–84.78%, 29.61%–40.68% and 1.68%–6.92% in high irradiance conditions, respectively. Chl-a in elevated pCO2 treatments was 7.75%–61.25% lower than ambient pCO2 conditions, while the carotenoid content increased by 12.12%–57.45% in low irradiance conditions from day 20–28. Malondialdehyde (MDA) content was higher in elevated pCO2 treatments. However, there was also a two- to four-fold increase in proline content in elevated pCO2 treatments. Tissue total organic carbon (TCorg) and nitrogen (TN) were positively correlated to CO2 enrichment. The results of the current study suggested that elevated pCO2 negatively influenced the physiological responses of Halimeda, while increased irradiance availability may enhance the metabolic performance in response to ocean acidification.

The effect of elevated pCO2 on cadmium resistance of a globally important diatom

Cadmium (Cd) pollution is a widespread threat to marine life, and ongoing ocean acidification (OA) is predicted to impact bio-toxicity of Cd compounds. However, the cascading effects of changed Cd toxicity to marine primary producers are not well characterized. Here, we studied the impact of OA on Cd toxicity responses in a globally important diatom Phaeodactylum tricornutum under both ambient and elevated pCO2 conditions. We found that increased pCO2 alleviated the impact of additive Cd toxicity on P. tricornutum not only under controlled indoor experiments but also in outdoor mesocosm experiments that reflect more natural growth conditions. Transcriptome analysis suggested that genes involved in Cd efflux and phytochelatin production were up-regulated and genes involved in Cd influx were down-regulated in long-term selected lineages under elevated pCO2. We further found a significant reduction of Cd transfer across trophic level, when the scallop Argopecten irradians was fed with Cd-exposed P. tricornutum previously cultured under elevated pCO2. Our results indicate that after long-term selection of P. tricornutum exposed to future OA conditions (i.e. elevated pCO2), the diatom alters its Cd detoxification strategy, which could have broader impacts on the bio-geochemical cycle of Cd in the marine ecosystem.

Towards the use of the coccolith vital effects in palaeoceanography: A field investigation during the middle Miocene in the SW Pacific Ocean

Recent culture studies of living coccolithophores have established a biogeochemical framework for the use of the geochemical compositions of their calcite biominerals as proxies in palaeoceanography. Yet, questions remain regarding the transferability of such experimental data to fossil coccoliths. Here we analysed the carbon and oxygen isotopic composition of Miocene coccoliths to assess the suitability of such data for reconstructing the past environment. We found that the oxygen isotopic compositions of the relatively small Noelaerhabdaceae coccoliths gathered in the 3–5 μm fractions appear to be a suitable material to derive temperatures after a correction for a constant vital offset of 0.8‰. The interpretation of the isotopic signal of the relatively large Coccolithales coccoliths (5–8 μm fractions) is more complex, but supports results from cultures. The expression of the carbon and oxygen vital effect in coccoliths appears to be limited during the so-called Miocene Climate Optimum (MCO), a period of relatively elevated atmospheric pCO2. Subsequently, during the Miocene Climatic Transition (MCT; ~14 Ma), which saw a decline in pCO2, large carbon and oxygen vital effects were expressed in coccolith calcite. This phenomenon predates the postulated “Late Miocene Threshold” by approximately 4 Ma, and cannot be reconciled as a temporally-synchronous nor localised feature. Furthermore, we observed a statistically significant correlation between the oxygen and carbon offsets of the small relative to large coccoliths (hence, the vital effect per se) that is likely linked to variations in atmospheric CO2. This biogeochemical correlation further supports a forcing of the environment on the cellular physiology (growth rate and utilisation of intracellular carbon) and ultimately the magnitude of isotopic vital effects in fossil coccoliths.

Combined effects of elevated temperature and pCO2 on the production of DMSP and DMS in the culture of Amphidinium carterae

Ocean acidification and global warming might affect the production of dimethylsulfoniopropionate (DMSP), dimethylsulfide (DMS), and dissolved acrylic acid (AAd) by marine phytoplankton. Monoculture incubation experiments were conducted with the dinoflagellate Amphidinium carterae to investigate the effects of elevated CO2 concentration and temperature on growth and productions of DMSP, DMS, and AAd. Two pCO2 levels were set as 400 and 1000 μatm, and two temperatures were set as 20 and 23 °C. The growth of A. carterae remained unaffected by an increase of CO2 to 1000 μatm and a rise of temperature of 3 °C. Moreover, the elevated CO2 concentration and temperature had no significant effects on the concentrations and cell-normalized concentrations of DMSP, DMS, and AAd. No additive or synergistic effects of elevated CO2 concentration and temperature on A. carterae were observed, indicating that A. carterae was insensitive to elevated CO2 and temperature in short time incubation.

Combined effect of pCO2 and temperature levels on the thermal niche in the early benthic ontogeny of a keystone species

We evaluated the effects of projected, near future ocean acidification (OA) and extreme events of temperature (warming or cooling) on the thermal tolerance of Concholepas concholepas, a coastal benthic keystone species. Three separate trials of an experiment were conducted by exposing juvenile C. concholepas for 1 month to one of two contrasting pCO2 levels (~500 and ~1200 μatm). In addition, each pCO2 level was combined with one of four temperature treatments. The control was 15 °C, whilst the other temperatures were 10 °C (Trial 1), 20 °C (Trial 2) and 25 °C (Trial 3). At the end of each trial, we assessed Critical Thermal maximum (CTmax) and minimum (CTmin) via self-righting success, calculated partial thermal tolerance polygons, measured somatic growth, determined transcription of Heat Shock Proteins 70 (HSP70) and measured oxygen consumption rates. Regardless of pCO2 level, HSP70 transcript levels were significantly higher in juveniles after exposure to extreme temperatures (10 °C and 25 °C) indicating physiological stress. Oxygen consumption rates increased with increasing temperature from 10 °C to 20 °C though showed a decrease at 25 °C. This rate was not affected by pCO2 or the interaction between temperature and pCO2. Juveniles exposed to present-day and near future pCO2 levels at 20 °C showed similar thermal tolerance polygonal areas; whilst changes in both CTmin and CTmax at 25 °C and 10 °C caused narrower and broader areas, respectively. Temperature affected growth, oxygen consumption and HSP70 transcription in small juvenile C. concholepas. Exposure to elevated pCO2 did not affect thermal tolerance, growth or oxygen consumption at temperatures within the thermal range normally experienced by this species in northern Chile (15-20 °C). At elevated pCO2 conditions, however, exposure to warmer (25 °C) or colder (10 °C) temperatures reduced or increased the thermal area, respectively. This study demonstrates the importance of examining the thermal-tolerance edges to better understand how OA and temperature will combine to physiologically challenge inter-tidal organisms.

Food availability modulates the combined effects of ocean acidification and warming on fish growth

When organisms are unable to feed ad libitum they may be more susceptible to negative effects of environmental stressors such as ocean acidification and warming (OAW). We reared sea bass (Dicentrarchus labrax) at 15 or 20 °C and at ambient or high PCO2 (650 versus 1750 µatm PCO2; pH = 8.1 or 7.6) at ad libitum feeding and observed no discernible effect of PCO2 on the size-at-age of juveniles after 277 (20 °C) and 367 (15 °C) days. Feeding trials were then conducted including a restricted ration (25% ad libitum). At 15 °C, growth rate increased with ration but was unaffected by PCO2. At 20 °C, acidification and warming acted antagonistically and low feeding level enhanced PCO2 effects. Differences in growth were not merely a consequence of lower food intake but also linked to changes in digestive efficiency. The specific activity of digestive enzymes (amylase, trypsin, phosphatase alkaline and aminopeptidase N) at 20 °C was lower at the higher PCO2 level. Our study highlights the importance of incorporating restricted feeding into experimental designs examining OAW and suggests that ad libitum feeding used in the majority of the studies to date may not have been suitable to detect impacts of ecological significance.

The effects of temperature and pCO2 on the size, thermal tolerance and metabolic rate of the red sea urchin (Mesocentrotus franciscanus) during early development

The red sea urchin Mesocentrotus franciscanus supports a highly valuable wild fishery along the West Coast of North America, but despite its importance in the ecology of kelp forests and as a harvested species, little is known about how M. franciscanus responds to abiotic stressors associated with ocean warming and acidification during its early development. Here, embryos of M. franciscanus were raised under combinations of two temperatures (13 °C and 17 °C) and two pCO2 levels (475 μatm and 1050 μatm) that represent current and future coastal environments. Elevated pCO2 levels led to a decrease in body size of gastrula stage embryos while temperature had no effect. At the prism stage, both temperature and pCO2 affected body size. The warmer temperature increased the body size of prism stage embryos, offsetting the stunting effect of elevated pCO2 on growth. Thermal tolerance, which was estimated by exposing prism stage embryos to a range of temperatures and estimating the survivorship, was found to be slightly higher in those raised under warmer temperatures. The developmental temperature and pCO2 conditions under which embryos were raised did not have an effect on the metabolic rate as measured by oxygen consumption rate at the prism stage. This study provides important insights into a species of high ecological and economic value. Overall, early development under elevated pCO2 conditions may adversely impact M. franciscanus while moderate warming may improve growth and thermal tolerance. Understanding how fishery species respond to abiotic stressors will facilitate our predictive capacity of how climate change will impact future populations, which links to issues such as sustainability and food security.

Year-long effects of high pCO2 on the community structure of a tropical fore reef assembled in outdoor flumes

Abstract In this study, fore reef coral communities were exposed to high pCO2 for a year to explore the relationship between net accretion (Gnet) and community structure (planar area growth). Coral reef communities simulating the fore reef at 17-m depth on Mo’orea, French Polynesia, were assembled in three outdoor flumes (each 500 l) that were maintained at ambient (396 µatm), 782 µatm, and 1434 µatm pCO2, supplied with seawater at 300 l h−1, and exposed to light simulating 17-m depth. The communities were constructed using corals from the fore reef, and the responses of massive Porites spp., Acropora spp., and Pocillopora verrucosa were assessed through monthly measurements of Gnet and planar area. High pCO2 depressed Gnet but did not affect colony area by taxon, although the areas of Acropora spp. and P. verrucosa summed to cause multivariate community structure to differ among treatments. These results suggest that skeletal plasticity modulates the effects of reduced Gnet at high pCO2 on planar growth, at least over a year. The low sensitivity of the planar growth of fore reef corals to the effects of ocean acidification (OA) on net calcification supports the counterintuitive conclusion that coral community structure may not be strongly affected by OA.

Effects of coastal acidification on North Atlantic bivalves: interpreting laboratory responses in the context of in situ populations.

Experimental exposure of early life stage bivalves has documented negative effects of elevated pCO2 on survival and growth, but the population consequences of these effects are unknown. Following standard practices from population viability analysis and wildlife risk assessment, we substituted laboratory-derived stress-response relationships into baseline population models of Mercenaria mercenaria and Argopecten irradians. The models were constructed using inverse demographic analyses with time series of size-structured field data in NY, USA, whereas the stress-response relationships were developed using data from a series of previously published laboratory studies. We used stochastic projection methods and diffusion approximations of extinction probability to estimate cumulative risk of 50% population decline during ten-year population projections at 1, 1.5 and 2 times ambient pCO2 levels. Although the A. irradians population exhibited higher growth in the field data (12% per year) than the declining M. mercenaria population (-8% per year), cumulative risk was high for A. irradians in the first ten years due to high variance in the stochastic growth rate estimate (log λs = -0.02, σ2 = 0.24). This ten-year cumulative risk increased from 69% to 94% and >99% at 1.5 and 2 times ambient scenarios. For M. mercenaria (log λs = -0.09, σ2 = 0.01), ten-year risk was 81%, 96% and >99% at 1, 1.5 and 2 times ambient pCO2, respectively. These estimates of risk could be improved with detailed consideration of harvest effects, disease, restocking, compensatory responses, other ecological complexities, and the nature of interactions between these and other effects that are beyond the scope of available data. However, results clearly indicate that early life stage responses to plausible levels of pCO2 enrichment have the potential to cause significant increases in risk to these marine bivalve populations.

Emergent properties of branching morphologies modulate the sensitivity of coral calcification to high PCO2.

Experiments with coral fragments (i.e. nubbins) have shown that net calcification is depressed by elevated PCO2 Evaluating the implications of this finding requires scaling of results from nubbins to colonies, yet the experiments to codify this process have not been carried out. Building from our previous research demonstrating that net calcification of Pocillopora verrucosa (2-13 cm diameter) was unaffected by PCO2 (400 and 1000 µatm) and temperature (26.5 and 29.7°C), we sought generality to this outcome by testing how colony size modulates PCO2 and temperature sensitivity in a branching acroporid. Together, these taxa represent two of the dominant lineages of branching corals on Indo-Pacific coral reefs. Two trials conducted over 2years tested the hypothesis that the seasonal range in seawater temperature (26.5 and 29.2°C) and a future PCO2 (1062 µatm versus an ambient level of 461 µatm) affect net calcification of an ecologically relevant size range (5-20 cm diameter) of colonies of Acropora hyacinthus As for P. verrucosa, the effects of temperature and PCO2 on net calcification (mgday-1) of A. verrucosa were not statistically detectable. These results support the generality of a null outcome on net calcification of exposing intact colonies of branching corals to environmental conditions contrasting seasonal variation in temperature and predicted future variation in PCO2 While there is a need to expand beyond an experimental culture relying on coral nubbins as tractable replicates, rigorously responding to this need poses substantial ethical and logistical challenges.

Resilience of Oxygen Consumption Rates in the Juvenile Blue Crab Callinectes sapidus to Future Predicted Increases in Environmental Temperature and pCo2 in the Mesohaline Chesapeake Bay

Quantifying the physiological impact of environmental stressors on living organisms is critical to predicting the response of any given species to future climate scenarios. Oxygen consumption rates (μmol/g/min) were measured to examine the physiological response of the juvenile blue crab Callinectes sapidus from the Chesapeake Bay (Patuxent River, Maryland) to elevated temperature and dissolved carbon dioxide in water (pCO2) reflective of projected future climate scenarios. Treatment levels were selected to represent current conditions in the Chesapeake Bay (26°C and 800 μatm) and conditions predicted to occur by the year 2100 (31°C and 8,000 μatm). Crabs were exposed in a factorial design to these conditions throughout two successive molts (approximately 30 days). At the end of the exposure, the oxygen consumption rates of individual crabs were determined over at least a 10-h period using a flow-through respiration chamber equipped with optical oxygen electrodes. No significant effect of temperature or pCO2 on oxygen consumption was observed, suggesting the absence of a respiratory impact of these two climate stressors on juvenile blue crabs. Oxygen consumption rates were also determined for crabs that experienced a rapid increase in temperature without prior acclimation. The oxygen consumption rate of crabs may have acclimated to increased temperature during the 30-day exposure period before respiratory measurement. This potential acclimation, combined with high individual variability, and a relatively small difference in temperature treatments are likely the cause for the lack of a statistically significant difference in mean oxygen consumption rates by temperature in the core experiment. The results of this study suggest that the blue crab may be quite resilient to future climate stressors and underscore the need for species-specific studies to quantify the effects of climate change on estuarine crustaceans.

Behavioral Defenses of Shellfish Prey under Ocean Acidification

Biological interactions between predators and prey constitute a key component of the ecology and evolution of marine systems, and animal behavior can affect the outcome of predator–prey interactions. It has been recently demonstrated that CO2-induced ocean acidification can alter the behavior of marine organisms and potentially alter predator–prey dynamics. This study combines both quantitative (meta-analysis) and qualitative approaches to review the effects of ocean acidification on behavioral prey defenses in marine invertebrates. A systematic literature search identified 34 studies that experimentally assessed behavioral defenses under elevated pCO2 spanning three phyla: crustaceans, echinoderms, and molluscs. A meta-analysis suggested that exposure to elevated seawater pCO2 can negatively affect behavioral defenses in bivalve molluscs and malacostracan crustaceans. By contrast, defenses of cephalopod molluscs seem to be positively impacted by elevated pCO2, whereas gastropods and echinoids appear unaffected. A qualitative assessment of studies on combined effects of ocean acidification and warming revealed that combined effects typically differ from ocean acidification–only effects. Based on a qualitative assessment of three studies to date, neurological interference of GABAA receptors under elevated pCO2 may play a major role in ocean acidification effects on prey defense behaviors; however, more research is needed, and other mechanistic underpinnings are also important to consider. Ultimately, the results of this study suggest that behavioral prey defenses in some shellfish taxa may be vulnerable to ocean acidification, that the effects of ocean acidification are often different under warming scenarios than under present-day temperature scenarios, and that GABAA interference may be an important mechanism underpinning behavioral responses of shellfish prey under ocean acidification. Despite the importance of shellfish behavioral defenses in the ecology and evolution of marine biological communities, however, research to date has only scraped the surface in understanding ocean acidification effects. Increased research efforts on the effects of multiple stressors, acclimation and adaptation, environmental variability, and complex situational and ecological contexts are needed. Studies of fish behavioral defenses under ocean acidification can help streamline hypotheses and experimental approaches, particularly given the similar effects of elevated pCO2 on GABAA function.

Subtropical freshwater phytoplankton show a greater response to increased temperature than to increased pCO2

Global increases in atmospheric CO2 and temperatures will impact aquatic systems, with freshwater habitats being affected. Some studies suggest that these conditions will promote cyanobacterial dominance. There is a need for a clearer picture of how algal species and strains within species will respond to higher temperatures and CO2, especially in combination. This study examined two chlorophytes (Monoraphidium and Staurastrum), and two strains of the cyanobacterium Raphidiopsis raciborskii (straight S07 and coiled C03), to determine how the combination of higher temperature and CO2 levels will affect their growth and maximum cell concentrations. Continuous cultures were used to compare the steady state cell concentrations at 28 °C and 30 °C, and CO2 partial pressures (pCO2), 400 and 750 ppm for all cultures, and in addition 1000 ppm at 28 °C for R. raciborskii strains. This study showed that, for all species, water temperature had a greater effect than higher pCO2 on cell concentrations. There were clear differences in response between the chlorophyte species, with Monoraphidium preferring 28 °C and Staurastrum preferring 30 °C. There were also differences in response of the R. raciborskii strains to increasing temperature and pCO2, with S07 having a greater increase in cell concentration. Genome analysis of R. raciborskii showed that the straight strain has five additional carbon acquisition genes (β-CA, chpY, cmpB, cmpD and NdhD4), indicative of increased carbon metabolism. These differences in the strains’ response to elevated pCO2 will lead to changes in the species population structure and distribution in the water column. This study shows that it is important to examine the effects of both pCO2 and temperature, and to consider strain variation, to understand how species composition of natural systems may change under future climate conditions.

Ocean acidification increases domoic acid contents during a spring to summer succession of coastal phytoplankton

Enrichment of the oceans with CO2 may be beneficial for some marine phytoplankton, including harmful algae. Numerous laboratory experiments provided valuable insights into the effects of elevated pCO2 on the growth and physiology of harmful algal species, including the production of phycotoxins. Experiments close to natural conditions are the next step to improve predictions, as they consider the complex interplay between biotic and abiotic factors that can confound the direct effects of ocean acidification. We therefore investigated the effect of ocean acidification on the occurrence and abundance of phycotoxins in bulk plankton samples during a long-term mesocosm experiment in the Gullmar Fjord, Sweden, an area frequently experiencing harmful algal blooms. During the experimental period, a total of seven phycotoxin-producing harmful algal genera were identified in the fjord, and in accordance, six toxin classes were detected. However, within the mesocosms, only domoic acid and the corresponding producer Pseudo-nitzschia spp. was observed. Despite high variation within treatments, significantly higher particulate domoic acid contents were measured in the mesocosms with elevated pCO2. Higher particulate domoic acid contents were additionally associated with macronutrient limitation. The risks associated with potentially higher phycotoxin levels in the future ocean warrants attention and should be considered in prospective monitoring strategies for coastal marine waters.

Elevated pCO2 does not impair performance in autotomised individuals of the intertidal predatory starfish Asterias rubens (Linnaeus, 1758)

The impacts of ocean acidification remain less well-studied in starfish compared to other echinoderm groups. This study examined the combined effects of elevated pCO2 and arm regeneration on the performance of the intertidal predatory starfish Asterias rubens, as both are predicted to come at a cost to the individual. A two-way factorial experiment (~400 μatm vs ~1000 μatm; autotomised vs non-automised individuals) was used to examine growth rates, lipid content (pyloric caeca and gonads), and calcium content (body wall) in both intact and regenerating arms, as well as subsequent effects on rate of arm regeneration, righting time (behaviour) and mortality over 120 days. Autotomised individuals tended to show lower (not significant), survival and growth. Elevated pCO2 had no effect on mortality, body growth, arm regeneration, righting time or arm calcium content. Lipid content was higher in the pyloric caeca, but not in the gonads, in response to elevated pCO2 irrespective of autotomisation. The results of the study suggest that adult A. rubens remain unaffected by increased pCO2 and/or arm autotomy for 120 days, although longer term experiments are necessary as the results indicated that survival, growth and calcification may be impaired with longer-term exposure to elevated pCO2.

Photosynthetic Responses of Turf-forming Red Macroalgae to High CO2 Conditions.

Seaweeds are important components of near-shore ecosystems as primary producers, foundation species, and biogeochemical engineers. Seaweed communities are likely to alter under predicted climate change scenarios. We tested the physiological responses of three perennial, turf-building, intertidal rhodophytes, Mastocarpus stellatus, Osmundea pinnatifida, and the calcified Ellisolandia elongata, to elevated pCO2 over 6weeks. Responses varied between these three species. E.elongata was strongly affected by high pCO2 , whereas non-calcified species were not. Elevated pCO2 did not induce consistent responses of photosynthesis and respiration across these three species. While baseline photophysiology differed significantly between species, we found few clear effects of elevated pCO2 on this aspect of macroalgal physiology. We found effects of within-species variation in elevated pCO2 response in M.stellatus, but not in the other species. Overall, our data confirm the sensitivity of calcified macroalgae to elevated pCO2 , but we found no evidence suggesting that elevated pCO2 conditions will have a strong positive or negative impact on photosynthetic parameters in non-calcified macroalgae.

Complex and interactive effects of ocean acidification and warming on the life span of a marine trematode parasite

Human activities have caused an increase in atmospheric CO2 over the last 250 years, leading to unprecedented rates of change in seawater pH and temperature. These global scale processes are now commonly referred to as ocean acidification and warming, and have the potential to substantially alter the physiological performance of many marine organisms. It is vital that the effects of ocean acidification and warming on marine organisms are explored so that we can predict how marine communities may change in future. In particular, the effect of ocean acidification and warming on host-parasite dynamics is poorly understood, despite the ecological importance of these relationships. Here, we explore the response of one himasthlid trematode, Himasthla sp., an abundant and broadly distributed species of marine parasite, to combinations of elevated temperature and pCO2 that represent physiological extremes, pre-industrial conditions, and end of century predictions. Specifically, we quantified the life span of the free-living cercarial stage under elevated temperature and pCO2, focussing our research on functional life span (the time cercariae spend actively swimming) and absolute life span (the period before death). We found that the effects of temperature and pCO2 were complex and interactive. Overall, increased temperature negatively affected functional and absolute life span, e.g. across all pCO2 treatments the average time to 50% cessation of active swimming was approximately 8 h at 5 °C, 6 h at 15 °C, 4 h at 25 °C, and 2 h at 40 °C. The effect of pCO2, which significantly affected absolute life span, was highly variable across temperature treatments. These results strongly suggest that ocean acidification and warming may alter the transmission success of trematode cercariae, and potentially reduce the input of cercariae to marine zooplankton. Either outcome could substantially alter the community structure of coastal marine systems.

Elevated seawater pCO2 affects reproduction and embryonic development in the pygmy squid, Idiosepius pygmaeus

The oceans are absorbing additional carbon dioxide (CO2) from the atmosphere and projected future CO2 levels and ocean acidification could have negative implications for many marine organisms, especially during early life stages. Cephalopods are ecologically important in marine ecosystems, yet the potential effects of increased partial pressure of CO2 (pCO2) in seawater on cephalopod reproduction and embryonic development are little studied. We allowed adult two-toned pygmy squid (Idiosepius pygmaeus) to breed in ambient control (~445 μatm; ~8.05 pHT) or elevated pCO2 conditions (~940 μatm; ~7.78 pHT) and compared reproductive traits in adults and developmental characteristics of their eggs, which remained in control or elevated pCO2 treatments until hatching. Breeding pairs at elevated pCO2 produced clutches with 40% fewer eggs, vitelli that were 14% smaller directly after spawning, embryos that were 5% smaller upon hatching, and eggs with an 8% increase in late-stage egg swelling compared with pairs at control conditions. Elevated pCO2 did not affect fertility, time to hatch, or hatching success. Eggs were laid 40% closer together in elevated pCO2 compared with control conditions, indicating a possible effect of elevated pCO2 on reproductive behaviour. These results show that elevated pCO2 can adversely affect reproduction and embryonic development of the two-toned pygmy squid. As the potential for adaptation is influenced by reproductive success, testing the capacity for squid to adapt to future ocean conditions should be a priority for future research.

Ocean acidification and food limitation combine to suppress herbivory by the gastropod Lacuna vincta

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 627:83-94 (2019) - DOI: https://doi.org/10.3354/meps13087 Ocean acidification and food limitation combine to suppress herbivory by the gastropod Lacuna vincta Craig S. Young, Alyson Lowell, Bradley Peterson, Christopher J. Gobler* School of Marine and Atmospheric Sciences, Stony Brook University, Southampton, NY 11968, USA *Corresponding author: christopher.gobler@stonybrook.edu ABSTRACT: While ocean acidification has different effects on herbivores and autotrophs, how acidification may influence herbivory is poorly understood. This study examined how grazing by the gastropod Lacuna vincta (hereafter Lacuna) on the macroalgae Ulva spp. (hereafter Ulva) is influenced by ocean acidification. Herbivory by Lacuna was significantly reduced under elevated partial pressure of carbon dioxide ( pCO2; 1500-2000 µatm) relative to ambient pCO2 (~400 µatm). This significant decrease in herbivory was unrelated to the physiological status of Ulva but rather was specifically elicited when Lacuna was exposed to elevated pCO2 in the absence of food for 18 to 24 h prior to grazing Ulva. The negative effects of elevated pCO2 on Lacuna were absent at 400 to 800 µatm pCO2 or when fed but persisted for up to 72 h following a 24 h exposure to elevated pCO2 without food. Depressed respiration rates in Lacuna following exposure to high pCO2 without food indicated these conditions produced metabolic suppression potentially associated with acidosis. Collectively, the lasting (72 h) nature of grazing inhibition of Lacuna following brief exposure (18 h) to moderate pCO2 levels (>~1500 µatm) when food was not available suggests this process could have broad effects on the dynamics of macroalgae in estuaries where Lacuna is a dominant grazer; these effects will be amplified as climate change progresses. KEY WORDS: Ocean acidification · Gastropods · Macroalgae · Grazing Full text in pdf format Supplementary material PreviousNextCite this article as: Young CS, Lowell A, Peterson B, Gobler CJ (2019) Ocean acidification and food limitation combine to suppress herbivory by the gastropod Lacuna vincta. Mar Ecol Prog Ser 627:83-94. https://doi.org/10.3354/meps13087 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 627. Online publication date: September 26, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Ocean acidification and warming effects on the physiology, skeletal properties, and microbiome of the purple-hinge rock scallop

Ocean acidification and increased ocean temperature from elevated atmospheric carbon dioxide can significantly influence the physiology, growth and survival of marine organisms. Despite increasing research efforts, there are still many gaps in our knowledge of how these stressors interact to affect economically and ecologically important species. This project is the first to explore the physiological effects of high pCO2 and temperature on the acclimation potential of the purple-hinge rock scallop (Crassadoma gigantea), a widely distributed marine bivalve, important reef builder, and potential aquaculture product. Scallops were exposed to two pCO2 (365 and 1050 μatm) and temperature (14 and 21.5 °C) conditions in a two-factor experimental design. Simultaneous exposure to high temperature and high pCO2 reduced shell strength, decreased outer shell density and increased total lipid content. Despite identical diets, scallops exposed to high pCO2 had higher content of saturated fatty acids, and lower content of polyunsaturated fatty acids suggesting reorganization of fatty acid chains to sustain basic metabolic functions under high pCO2. Metagenomic sequencing of prokaryotes in scallop tissue revealed treatment differences in community composition between treatments and in the presence of genes associated with microbial cell regulation, signaling, and pigmentation. Results from this research highlight the complexity of physiological responses for calcifying species under global change related stress and provide the first insights for understanding the response of a bivalve's microbiome under multiple stressors.