Ocean acidification (OA) driven by sea water uptake of anthropogenic atmospheric CO2 has broad deleterious effects on marine species including modified behavioural interactions such as between predators and prey. Predatory sea stars are key species in many marine ecosystems and often elicit defensive responses in their prey. This study investigated the effect of elevated CO2 on the escape response of the sea star Parvulastra exigua to its sea star predator Meridiastra calcar. In response to touch by M. calcar, P. exigua exhibits a distinct fleeing response. The escape response of P. exigua with respect to velocity and escape trajectory was investigated after both species were acclimated in OA conditions. At pHT 7.6 and 7.8 velocity and escape trajectory of the fleeing response of P. exigua did not differ from that seen in the ambient treatment. However, there was a delay in the time that P. exigua started to flee with the initiation time being 2.8 times slower (10 vs 28 s) at pHT 7.6. This delay may increase the vulnerability of P. exigua to predation by M. calcar and have ecological effects with respect to the role of this species as an algal grazer on rocky shores of southeast Australia where these sea star species co-occur.
Continue reading ‘The effect of ocean acidification on the escape behaviour of the sea star Parvulastra exigua to its sea star predator Meridiastra calcar’Posts Tagged 'performance'
The effect of ocean acidification on the escape behaviour of the sea star Parvulastra exigua to its sea star predator Meridiastra calcar
Published 15 July 2022 Science ClosedTags: biological response, BRcommunity, echinoderms, laboratory, multiple factors, performance, predation, South Pacific
EcoPhysioMechanics: integrating energetics and biomechanics to understand fish locomotion under climate change
Published 7 July 2022 Science ClosedTags: biological response, fish, morphology, performance, physiology, review
Ecological physiologists and biomechanists have been broadly investigating swimming performance in a diversity of fishes, however the connection between form, function and energetics of locomotion has been rarely evaluated in the same system and under climate change scenarios. In this perspective I argue that working within the framework of ‘EcoPhysioMechanics’, i.e., integrating energetics and biomechanics tools, to measure locomotor performance and behavior under different abiotic factors, improves our understanding of the mechanisms, limits and costs of movement. To demonstrate how ecophysiomechanics can be applied to locomotor studies, I outline how linking biomechanics and physiology allows us to understand how fishes may modulate their movement to achieve high speeds or reduce the costs of locomotion. I also discuss how the framework is necessary to quantify swimming capacity under climate change scenarios. Finally, I discuss current dearth of integrative studies and gaps in empirical datasets that are necessary to understand fish swimming under changing environments.
Continue reading ‘EcoPhysioMechanics: integrating energetics and biomechanics to understand fish locomotion under climate change ‘Microplastics can aggravate the impact of ocean acidification on the health of a common mussel: insights from physiological performance, immunity and byssus properties
Published 5 July 2022 Science ClosedTags: biological response, mollusks, morphology, multiple factors, performance, physiology, toxicants
Highlights
- Ocean acidification reduced phagocytic activity and hence immunity of mussels.
- The reduced phagocytic activity was associated with lowered energy budget.
- Ocean acidification also reduced byssus strength, extensibility and production.
- Microplastics can aggravate these negative effects of ocean acidification.
- Mussels would be more prone to diseases and dislodgement in future oceans.
Abstract
Ocean acidification may increase the risk of disease outbreaks that would challenge the future persistence of marine organisms if their immune system and capacity to produce vital structures for survival (e.g., byssus threads produced by bivalves) are compromised by acidified seawater. These potential adverse effects may be exacerbated by microplastic pollution, which is forecast to co-occur with ocean acidification in the future. Thus, we evaluated the impact of ocean acidification and microplastics on the health of a common mussel (Mytilus coruscus) by assessing its physiological performance, immunity and byssus properties. We found that ocean acidification and microplastics not only reduced hemocyte concentration and viability due to elevated oxidative stress, but also undermined phagocytic activity of hemocytes due to lowered energy budget of mussels, which was in turn caused by the reduced feeding performance and energy assimilation of mussels. Byssus quality (strength and extensibility) and production were also reduced by ocean acidification and microplastics. To maximize survival with these stressors, the mussels prioritized the synthesis of some byssus proteins (Mfp-4 and Mfp-5) to help maintain adhesion to substrata. Nevertheless, our findings suggest that the future co-occurrence of ocean acidification and microplastic pollution would increase the susceptibility of bivalves to infectious diseases and dislodgement risk, thereby threatening their survival and undermining their ecological contributions to the community.
Continue reading ‘Microplastics can aggravate the impact of ocean acidification on the health of a common mussel: insights from physiological performance, immunity and byssus properties’Becoming nose-blind—climate change impacts on chemical communication
Published 31 May 2022 Science ClosedTags: biological response, crustaceans, mollusks, multiple factors, performance, phanerogams, physiology, reproduction, review, temperature, zooplankton
Chemical communication via infochemicals plays a pivotal role in ecological interactions, allowing organisms to sense their environment, locate predators, food, habitats, or mates. A growing number of studies suggest that climate change-associated stressors can modify these chemically mediated interactions, causing info-disruption that scales up to the ecosystem level. However, our understanding of the underlying mechanisms is scarce. Evidenced by a range of examples, we illustrate in this opinion piece that climate change affects different realms in similar patterns, from molecular to ecosystem-wide levels. We assess the importance of different stressors for terrestrial, freshwater, and marine ecosystems and propose a systematic approach to address highlighted knowledge gaps and cross-disciplinary research avenues.
Continue reading ‘Becoming nose-blind—climate change impacts on chemical communication’Ocean acidification alters the acute stress response of a marine fish
Published 27 May 2022 Science ClosedTags: biological response, fish, laboratory, molecular biology, performance, physiology, reproduction
The absorption of anthropogenic carbon dioxide in the atmosphere by oceans generates rapid changes in seawater carbonate system and pH, a process termed ocean acidification. Exposure to acidified water can impact the allostatic load of marine organism as the acclimation to suboptimal environments requires physiological adaptive responses that are energetically costly. As a consequence, fish facing ocean acidification may experience alterations of stress response and a compromised ability to cope to additional stress which may impact individuals’ life traits and ultimately their fitness. In this context, we carried out an integrative study investigating the impact of ocean acidification on the physiological and behavioral stress responses to an acute stress in juvenile European sea bass. Fish were long term (11 months) exposed to present day pH/CO 2 condition or acidified water as predicted by IPCC “as business as usual” (RCP8.5) scenario for 2100 and subjected to netting and confinement tests. Fish acclimated to RCP8.5 scenario showed slower post stress return to plasma basal concentrations of cortisol and glucose. We found no clear indication of regulation in the central and interrenal tissues of the expression levels of gluco- and mineralocorticoid receptors and corticoid releasing factor. At 120 minutes post stress, sea bass acclimated to acidified water had divergent neurotransmitters’ concentrations pattern in the hypothalamus (higher serotonin levels and lower GABA and dopamine levels) and a reduction in motor activity. Our experimental data indicate that ocean acidification alters the physiological response to acute stress in European sea bass via the neuroendocrine regulation of the corticotropic axis, a response associated to an alteration of the motor behavioral profile. Overall, this study suggests that behavioral and physiological adaptive response to climate changes related constraints may impact fish resilience to further stressful events.
Continue reading ‘Ocean acidification alters the acute stress response of a marine fish’Transgenerational effects and phenotypic plasticity in sperm and larvae of the sea urchin Paracentrotus lividus under ocean acidification
Published 26 May 2022 Science ClosedTags: biological response, echinoderms, laboratory, morphology, mortality, performance, physiology, reproduction
Highlights
- Transgenerational effects of OA were studied in P. lividus sperm and larvae
- Gametogenesis under OA resulted in increased sperm ATP content
- Slower decrease of swimming velocity was found in sperm from males kept at low pH
- Parental exposure to OA decreased larval survival but increased larval growth
- Parental pH affected offspring performances more than post-spawning pH
Abstract
In marine organisms, differing degree of sensitivity to ocean acidification (OA) is expected for each life stage, and disturbance at one stage can carry over into the following stage or following generation. In this study we investigated phenotypic changes of sperm and larvae of the sea urchin Paracentrotus lividus in response to different pH conditions (8.0, 7.7, 7.4) experienced by the parents during gametogenesis. In sperm from two-months exposed males, sperm motility, velocity, ATP content, ATP consumption and respiration rate were evaluated at three pH values of the activating medium (8.0, 7.7 and 7.4). Moreover, larvae from each parental group were reared at pH 8.0 and 7.7 for 20 days and larval mortality and growth were then assessed. Sperm motility and respiration rate were not affected either by exposure of males to low pH or by the post-activation pH. Sperm velocity did not differ among post-activation pH values in all sperm groups, but it decreased slower in sperm developed under acidified conditions, suggesting the presence of positive carryover effect on sperm longevity. This positive carryover effect of exposure of males to low pH values was highlighted also for the sperm ATP content, which was higher in these groups of sperm. ATP consumption rate was affected by post-activation pH with higher values at pH 8.0 in sperm from males maintained at control condition and pH 7.7 while the energy consumption appeared to be differently modulated at different experimental conditions. A negative carry over effect of OA was observed on survival of larvae from parents acclimated at pH 7.4 and additive negative effects of both parental and larval exposure to low pH can be suggested. In all groups of larvae, decreased somatic growth was observed at low rearing pH, thus larvae from parents maintained at low pH did not show an increased capability to cope with OA.
Continue reading ‘Transgenerational effects and phenotypic plasticity in sperm and larvae of the sea urchin Paracentrotus lividus under ocean acidification’Otolith development and elemental incorporation in response to seawater acidification in the flounder Paralichthys olivaceus at early life stages
Published 11 May 2022 Science ClosedTags: biological response, fish, laboratory, performance, physiology, reproduction
Highlights
- Ocean acidification promoted otolith growth but not changed otolith shape.
- Ocean acidification did not alter somatic growth or otolith elemental incorporation.
- Ocean acidification induced and increased the occurrence of irregular calcitic otoliths.
- Elemental incorporation is higher in aragonitic otoliths than in calcitic otoliths.
Abstract
Ocean acidification can influence the formation, development and functions of calcified structures in marine organisms, such as otoliths, which are mainly composed of calcium carbonate (CaCO3) and function in orientation, balance, sensory perception and locomotion in fish. This study investigated the impacts of seawater acidification (pH 8.10, 7.70 and 7.30, roughly corresponding to the ocean acidification under RCP 8.5 scenario predicted by the IPCC) on somatic growth, otolith (aragonite) morphology and microchemistry in the flounder Paralichthys olivaceus at early life stages (ELSs, exposed to acidified seawater via pCO2 from embryonic to juvenile stages for 52 days). The results demonstrated that seawater acidification promoted otolith growth (mass and size) but did not change their geometric outlines. Seawater acidification did not alter the somatic growth or otolith elemental incorporation (Sr, Ba and Mg) in the flounder. Seawater acidification increased the occurrence of abnormally developed calcitic otoliths (calcite) which considerably differed from the aragonitic otoliths in surface and crystal structures. Additionally, elemental incorporation (Sr:Ca and Ba:Ca) appeared to be higher in aragonitic otoliths than in calcitic otoliths, which was likely related to their unique manners of formation. Our results agreed with the broad literature, in that seawater acidification showed species-specific influences (positive or no effect) on otolith size but did not affect somatic growth, otolith shape or elemental incorporation of fish at ELSs. These findings provide knowledge for evaluating the ecological effects of ocean acidification on the recruitment and population dynamics of fish in the wild.
Continue reading ‘Otolith development and elemental incorporation in response to seawater acidification in the flounder Paralichthys olivaceus at early life stages’Reanalysis shows the extreme decline effect does not exist in fish ocean acidification studies
Published 13 April 2022 Science ClosedTags: biological response, fish, laboratory, performance, physiology
Contradictory Results
A meta-analysis published in PLoS Biology by Clements et al. (2022) claims there is an extreme decline effect in studies published between 2009-2019 on the impacts of ocean acidification (OA) on fish behaviour. Here I show that the extreme decline effect reported by Clements et al. is a statistical artifact caused by the way they corrected for zero values in percentage data, which was more common in the earliest experiments compared with later studies. Furthermore, selective choices for excluding or including data, along with serious errors in the compilation of data and missing studies with strong effects, weakened the effect sizes reported for papers after 2010, further exacerbating the decline effect reported by Clements et al. When the data is reanalyzed using appropriate corrections for zero values in percentage and proportional data, and using a complete, corrected and properly screened data set, the extreme decline effect reported by Clements et al. no longer exists.
Continue reading ‘Reanalysis shows the extreme decline effect does not exist in fish ocean acidification studies’Predicted future changes in ocean temperature and pH do not affect prey selection by the girdled dogwhelk Trochia cingulata
Published 4 April 2022 Science ClosedTags: biological response, laboratory, mollusks, mortality, multiple factors, performance, temperature
Predator–prey relationships can drive community dynamics in marine systems, but it remains unclear how future changes in seawater temperatures and pH will influence these relationships. This study assessed the effect of predicted future temperatures and pH on the prey choice of the girdled dogwhelk Trochia cingulata (family Muricidae) when offered native (Aulacomya atra, Choromytilus meridionalis) and alien (Semimytilus algosus) mussels. Whelks were exposed to three pH levels: 8.0 (current), 7.7 (intermediate) and 7.5 (extreme), at each of three temperatures: 9 °C (cooling), 13 °C (current) and 17 °C (warming) for 6 weeks. Thereafter, the prey preference and predation rate were compared among treatments. Within two weeks, 98% of whelks exposed to warming died, precluding assessment of how warming affects their prey preference. Despite high mortality, the highest predation rates were recorded at 17 °C regardless of the pH level, likely reflecting increased energy costs and ingestion rates associated with warming. In the remaining treatments whelks preferred S. algosus irrespective of the levels of seawater cooling or acidification. These results align with previous work that demonstrated a preference by T. cingulata for S. algosus and suggest that the predator–prey relationship between this whelk and its mussel prey is unlikely to be disrupted under future marine conditions.
Continue reading ‘Predicted future changes in ocean temperature and pH do not affect prey selection by the girdled dogwhelk Trochia cingulata’Effects of seawater acidification on echinoid adult stage: a review
Published 1 April 2022 Science ClosedTags: adaptation, calcification, echinoderms, otherprocess, performance, physiology, reproduction, review, vents
The continuous release of CO2 in the atmosphere is increasing the acidity of seawater worldwide, and the pH is predicted to be reduced by ~0.4 units by 2100. Ocean acidification (OA) is changing the carbonate chemistry, jeopardizing the life of marine organisms, and in particular calcifying organisms. Because of their calcareous skeleton and limited ability to regulate the acid–base balance, echinoids are among the organisms most threatened by OA. In this review, 50 articles assessing the effects of seawater acidification on the echinoid adult stage have been collected and summarized, in order to identify the most important aspects to consider for future experiments. Most of the endpoints considered (i.e., related to calcification, physiology, behaviour and reproduction) were altered, highlighting how various and subtle the effects of pH reduction can be. In general terms, more than 43% of the endpoints were modified by low pH compared with the control condition. However, animals exposed in long-term experiments or resident in CO2-vent systems showed acclimation capability. Moreover, the latitudinal range of animals’ distribution might explain some of the differences found among species. Therefore, future experiments should consider local variability, long-term exposure and multigenerational approaches to better assess OA effects on echinoids.
Continue reading ‘Effects of seawater acidification on echinoid adult stage: a review’High CO2 inhibits substratum exploration and settlement of coral larvae
Published 28 March 2022 Science ClosedTags: algae, biological response, BRcommunity, corals, laboratory, performance, reproduction
Biological and physical factors affecting coral recruitment are critical in influencing the recovery of coral communities after disturbance. While ocean acidification (OA) can reduce coral settlement and the early growth of coral recruits, the impact of OA on coral larval swimming behavior is unknown. Here, we investigated the effects of elevated CO2 on the swimming behavior and settlement of coral larvae of 2 common Acropora species. Larvae were exposed to 4 CO2 partial pressure (pCO2) conditions consistent with the current Intergovernmental Panel for Climate Change predictions for the next few centuries (pCO2: 393, 853, 1485, 3022 µatm; pH: 8.1, 7.8, 7.6, 7.3) in 2 laboratory experiments. We found that bottom exploration, expressed as the proportion of A. cytherea and A. pulchra larvae present in the bottom part of experimental cylinders, decreased by 92 and 98%, respectively, from the ambient to highest CO2 treatment. When offered the choice to settle on the crustose coralline algae Titanoderma prototypum, a well-known positive settlement cue, the percentage of larvae that settled on the crustose coralline algae fragments declined rapidly as pCO2 increased, with no larvae settling in the highest CO2 treatment. These results suggest that OA may negatively affect coral recruitment via direct effects on larval swimming behavior, with larvae avoiding benthic probing in response to high CO2.
Continue reading ‘High CO2 inhibits substratum exploration and settlement of coral larvae’Low-pH seawater alters indirect interactions in rocky-shore tidepools
Published 25 March 2022 Science ClosedTags: algae, biological response, community composition, echinoderms, field, mollusks, North Pacific, performance
Ocean acidification is expected to degrade marine ecosystems, yet most studies focus on organismal-level impacts rather than ecological perturbations. Field studies are especially sparse, particularly ones examining shifts in direct and indirect consumer interactions. Here we address such connections within tidepool communities of rocky shores, focusing on a three-level food web involving the keystone sea star predator, Pisaster ochraceus, a common herbivorous snail, Tegula funebralis, and a macroalgal basal resource, Macrocystis pyrifera. We demonstrate that during nighttime low tides, experimentally manipulated declines in seawater pH suppress the anti-predator behavior of snails, bolstering their grazing, and diminishing the top-down influence of predators on basal resources. This attenuation of top-down control is absent in pools maintained experimentally at higher pH. These findings suggest that as ocean acidification proceeds, shifts of behaviorally mediated links in food webs could change how cascading effects of predators manifest within marine communities.
Continue reading ‘Low-pH seawater alters indirect interactions in rocky-shore tidepools’Swimming performance of sharks and rays under climate change
Published 21 March 2022 Science ClosedTags: biological response, fish, performance, review
Climate change stressors (e.g., warming and ocean acidification) are an imminent challenge to the physiological performance of marine organisms. Several studies spanning the last decade have reported widespread effects of warming and acidification on marine fishes, especially teleosts, but more work is needed to elucidate the responses in marine elasmobranchs, i.e., sharks and rays. Dispersal capacity, as a result of locomotor performance, is a crucial trait that will determine which group of elasmobranchs will be more or less vulnerable to changes in the environment. In fact, efficient and high locomotor performance may determine the capacity for elasmobranchs to relocate to a more favorable area. In this review we integrate findings from work on locomotion of marine sharks and rays to identify characteristics that outline potential vulnerabilities and strength of sharks and rays under climate change. Traits such as intraspecific variability in response to climatic stressors, wide geographic range, thermotaxis, fast swimming or low energetic costs of locomotion are likely to enhance the capacity to disperse. Future studies may focus on understanding the interacting effect of climatic stressors on morphology, biomechanics and energetics of steady and unsteady swimming, across ontogeny and species.
Continue reading ‘Swimming performance of sharks and rays under climate change’Elevated temperature and low pH affect the development, reproduction, and feeding preference of the tropical cyclopoid copepod Oithona rigida
Published 18 March 2022 Science ClosedTags: biological response, crustaceans, laboratory, multiple factors, performance, reproduction, temperature, zooplankton
The copepod genus Oithona is among the most abundant mesozooplankton in both eutrophic and oligotrophic waters. This paper reports the individual and combined effect of temperature and pH on the development, reproduction success, and feeding preference of the tropical species Oithona rigida. Experiments were conducted at different temperature (28, 30, 31, and 32°C) and pH (7.7, 7.9, and 8.1) conditions. Effects on vital rates were observed for different developmental stages and adult males. Sex ratio varied from near 1:1 at 28°C to almost entirely female at 32°C. Egg production and hatching success were maximum at 30°C and pH at 7.9. O. rigida preferred the motile green alga Dunaliella salina in terms of ingestion rate, feed selectivity, and egg production across all the temperature and pH conditions. Long-term studies are needed to validate the adaptability of this species to a variety of climate impacts.
Continue reading ‘Elevated temperature and low pH affect the development, reproduction, and feeding preference of the tropical cyclopoid copepod Oithona rigida’GABA receptors in the olfactory epithelium of the gilthead seabream (Sparus aurata)
Published 15 March 2022 Science ClosedTags: biological response, fish, laboratory, performance, physiology
Exposure to high PCO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl−/HCO3− currents through GABAA receptors (the GABAA receptor theory). However, the main evidence for this is that gabazine, a GABAA receptor antagonist, reverses these effects when applied to the water, assuming that exposure to systems other than the CNS would be without effect. Here, we show the expression of both metabotropic and ionotropic GABA receptors, and the presence of GABAA receptor protein, in the olfactory epithelium of gilthead seabream. Furthermore, exposure of the olfactory epithelium to muscimol (a specific GABAA receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABAA receptors in the olfactory epithelium is not yet clear, this may complicate the interpretation of studies wherein water-borne gabazine is used to reverse the effects of high CO2 levels on olfactory-driven behaviour in fish.
Continue reading ‘GABA receptors in the olfactory epithelium of the gilthead seabream (Sparus aurata)’A systematic review of the behavioural changes and physiological adjustments of elasmobranchs and teleost’s to ocean acidification with a focus on sharks
Published 8 March 2022 Science ClosedTags: biological response, BRcommunity, fish, performance, physiology, review
In recent years, much attention has been focused on the impact of climate change, particularly via ocean acidification (OA), on marine organisms. Studying the impact of OA on long-living organisms, such as sharks, is especially challenging. When the ocean waters absorb anthropogenic carbon dioxide (CO2), slow-growing shark species with long generation times may be subjected to stress, leading to a decrease in functionality. Our goal was to examine the behavioral and physiological responses of sharks to OA and the possible impacts on their fitness and resilience. We conducted a systematic review in line with PRISMA-Analyses, of previously reported scientific experiments. We found that most studies used CO2 partial pressures (pCO2) that reflect representative concentration pathways for the year 2100 (e.g., pH ~7.8, pCO2 ~1000 μatm). Since there is a considerable knowledge gap on the effect of OA on sharks, we utilized existing data on bony fish to synthesize the available knowledge. Given the similarities between the behaviors and physiology of these two superclasses’ to changes in CO2 and pH levels, there is merit in including the available information on bony fish as well. Several studies indicated a decrease in shark fitness in relation to increased OA and CO2 levels. However, the decrease was species-specific and influenced by the intensity of the change in atmospheric CO2 concentration and other anthropogenic and environmental factors (e.g., fishing, temperature). Most studies involved only limited exposure to future environmental conditions and were conducted on benthic shark species studied in the laboratory rather than on apex predator species. While knowledge gaps exist, and more research is required, we conclude that anthropogenic factors are likely contributing to shark species’ vulnerability worldwide. However, the impact of OA on the long-term stability of shark populations is not unequivocal.
Continue reading ‘A systematic review of the behavioural changes and physiological adjustments of elasmobranchs and teleost’s to ocean acidification with a focus on sharks’Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod
Published 8 March 2022 Science ClosedTags: biological response, BRcommunity, calcification, crustaceans, laboratory, mollusks, morphology, mortality, performance, physiology
Highlights
- Snail feeding was reduced by Non-Consumptive Effects (NCEs) of a predatory crab.
- Snail feeding was not reduced by ocean acidification (OA) and warming (OW).
- Snail tenacity was reduced by OA but only under predatory crab NCEs.
- Snail survival and growth were resilient to OA, OW and NCEs.
Abstract
To understand how climate change stressors might affect marine organisms and support adequate projections it is important to know how multiple stressors may be modulated by the presence of other species. We evaluated the direct effects of ocean warming (OW) and ocean acidification (OA) together with non-consumptive effects (NCEs) of the predatory crab Acanthocyclus hassleri on early ontogeny fitness-related traits of the commercially important rocky-shore keystone gastropod Concholepas concholepas. We measured the response of nine traits to these stressors at either the organismal level (survival, growth, feeding rates, tenacity, metabolic rate, calcification rate) or sub-organismal level (nutritional status, ATP-supplying capacity, stress condition). C. concholepas survival was not affected by any of the stressors. Feeding rates were not affected by OW or OA; however, they were reduced in the presence of crab NCEs compared with control conditions. Horizontal tenacity was affected by the OA × NCEs interaction; in the presence of NCEs, OA reduced tenacity. The routine metabolic rate, measured by oxygen consumption, increased significantly with OW. Nutritional status assessment determined that carbohydrate content was not affected by any of the stressors. However, protein content was affected by the OA × NCEs interaction; in the absence of NCEs, OA reduced protein levels. ATP-supplying capacity, measured by citrate synthase (CS) activity, and cellular stress condition (HSP70 expression) were reduced by OA, with reduction in CS activity found particularly at the high temperature. Our results indicate C. concholepas traits are affected by OA and OW and the effects are modulated by predator risk (NCEs). We conclude that some C. concholepas traits are resilient to climate stressors (survival, growth, horizontal tenacity and nutritional status) but others are affected by OW (metabolic rate), OA (ATP-supplying capacity, stress condition), and NCEs (feeding rate). The results suggest that these negative effects can adversely affect the associated community.
Continue reading ‘Multiple-stressor effects of ocean acidification, warming and predation risk cues on the early ontogeny of a rocky-shore keystone gastropod’Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus
Published 1 March 2022 Science ClosedTags: biological response, echinoderms, laboratory, Mediterranean, multiple factors, performance, reproduction, toxicants
Ocean acidification poses an increasing concern for broadcast spawning species that release gametes in the water column where fertilization occurs. Indeed, the functionality of gametes and their interactions may be negatively affected by reduced pH. Susceptibility to other environmental stressors, such as pollutants, may be also altered under acidified conditions, resulting in more detrimental effects. To verify this hypothesis, combined exposures to CO2-driven acidification and environmentally relevant concentrations (0.5 µg/L) of three contaminants (caffeine, diclofenac, and PFOS, all singularly or in mixture) were carried out to highlight potential negative effects on fertilization success and motility of sperm in the sea urchin Paracentrotus lividus. Our results showed a significant reduction in the percentage of fertilized eggs when sperm were pre-exposed to reduced pH (ambient pH minus 0.4 units) compared to that of controls (ambient, pH = 8.1). Sperm speed and motility also decreased when sperm were activated and then exposed at reduced pH. Conversely, at both pH values tested, no significant effect due to the contaminants, nor of their interaction with pH, was found on any of the biological endpoints considered.
Continue reading ‘Ocean acidification, but not environmental contaminants, affects fertilization success and sperm motility in the sea urchin Paracentrotus lividus’On the effects of temperature and pH on tropical and temperate holothurians
Published 8 February 2022 Science ClosedTags: biological response, echinoderms, individualmodeling, laboratory, modeling, morphology, multiple factors, performance, physiology, reproduction, temperature
Ocean acidification and increased ocean heat content has direct and indirect effects on marine organisms such as holothurians (sea cucumbers) that are vulnerable to changes in pH and temperature. These environmental factors have the potential to influence organismal performance and fitness at different life stages. Tropical and temperate holothurians are more vulnerable to temperature and pH than those from colder water environments. The high level of environmental variation observed in the oceans could influence organismal responses and even produce a wide spectrum of compensatory physiological mechanisms. It is possible that in these areas, larval survival will decline by up to 50% in response to a reduction of 0.5 pH units. Such reduction in pH may trigger low intrinsic growth rates and affect the sustainability of the resource. Here we describe the individual and combined effects that temperature and pH could produce in these organisms. We also describe how these effects can scale from individuals to the population level by using age-structured spatial models in which depensation can be integrated. The approach shows how physiology can improve the conservation of the resource based on the restriction of growth model parameters and by including a density threshold, below which the fitness of the population, specifically intrinsic growth rate, decreases.
Continue reading ‘On the effects of temperature and pH on tropical and temperate holothurians’Meta-analysis reveals an extreme “decline effect” in the impacts of ocean acidification on fish behavior
Published 4 February 2022 Science ClosedTags: biological response, fish, laboratory, performance, physiology
Ocean acidification—decreasing oceanic pH resulting from the uptake of excess atmospheric CO2—has the potential to affect marine life in the future. Among the possible consequences, a series of studies on coral reef fish suggested that the direct effects of acidification on fish behavior may be extreme and have broad ecological ramifications. Recent studies documenting a lack of effect of experimental ocean acidification on fish behavior, however, call this prediction into question. Indeed, the phenomenon of decreasing effect sizes over time is not uncommon and is typically referred to as the “decline effect.” Here, we explore the consistency and robustness of scientific evidence over the past decade regarding direct effects of ocean acidification on fish behavior. Using a systematic review and meta-analysis of 91 studies empirically testing effects of ocean acidification on fish behavior, we provide quantitative evidence that the research to date on this topic is characterized by a decline effect, where large effects in initial studies have all but disappeared in subsequent studies over a decade. The decline effect in this field cannot be explained by 3 likely biological explanations, including increasing proportions of studies examining (1) cold-water species; (2) nonolfactory-associated behaviors; and (3) nonlarval life stages. Furthermore, the vast majority of studies with large effect sizes in this field tend to be characterized by low sample sizes, yet are published in high-impact journals and have a disproportionate influence on the field in terms of citations. We contend that ocean acidification has a negligible direct impact on fish behavior, and we advocate for improved approaches to minimize the potential for a decline effect in future avenues of research.
Continue reading ‘Meta-analysis reveals an extreme “decline effect” in the impacts of ocean acidification on fish behavior’
