Transgenerational deleterious effects of ocean acidification on the reproductive success of a keystone crustacean (Gammarus locusta)

Acid times in physiology: A systematic review of the effects of ocean acidification on calcifying invertebrates

The reduction in seawater pH from rising levels of carbon dioxide (CO₂) in the oceans has been recognized as an important force shaping the future of marine ecosystems. Therefore, numerous studies have reported the effects of ocean acidification (OA) in different compartments of important animal groups, based on field and/or laboratory observations. Calcifying invertebrates have received considerable attention in recent years. In the present systematic review, we have summarized the physiological responses to OA in coral, echinoderm, mollusk, and crustacean species exposed to predicted ocean acidification conditions in the near future. The Scopus, Web of Science, and PubMed databases were used for the literature search, and 75 articles were obtained based on the inclusion criteria. Six main physiological responses have been reported after exposure to low pH. Growth (21.6%), metabolism (20.8%), and acid-base balance (17.6%) were the most frequent among the phyla, while calcification and growth were the physiological responses most affected by OA (>40%). Studies show that the reduction of pH in the aquatic environment, in general, supports the maintenance of metabolic parameters in invertebrates, with redistribution of energy to biological functions, generating limitations to calcification, which can have severe consequences for the health and survival of these organisms. It should be noted that the OA results are variable, with inter and/or intraspecific differences. In summary, this systematic review offers important scientific evidence for establishing paradigms in the physiology of climate change in addition to gathering valuable information on the subject and future research perspectives.

Anthropogenic noise may impair the mating behaviour of the Shore Crab Carcinus Maenas

Anthropogenic noise is a recent addition to the list of human-made threats to the environment, with potential and established negative impacts on a wide range of animals. Despite their economic and ecological significance, few studies have considered the impact of anthropogenic noise on crustaceans, though past studies have shown that it can cause significant effects to crustacean physiology, anatomy, and behaviour. Mating behaviour in crustaceans could potentially be severely affected by anthropogenic noise, given that noise has been demonstrated to impact some crustacean’s ability to detect and respond to chemical, visual, and acoustic cues, all of which are vital in courtship rituals. To explore if noise has an impact on crustacean mating, we tested the responses of male green shore crabs (Carcinus maenas) from the southwest UK coast by exposing them to ship noise recordings while simultaneously presenting them with a dummy-female soaked in the female-sex pheromone uridine diphosphate (UDP) in an experimental tank setup (recording treatment: n = 15, control treatment: n = 15). We found a significant, negative effect of noise on the occurrence of mating behaviour compared to no noise conditions, though no significant effect of noise on the time it took for a crab to respond to the pheromone. Such effects suggest reproductive impairment due to anthropogenic noise, which could potentially contribute to decreased crustacean populations and subsequent ecological and economic repercussions. Given the findings of our preliminary study, more research should be undertaken that includes larger sample sizes, double blind setups, and controlled laboratory trials in order to more fully extrapolate the potential impact of noise on mating in the natural environment.

Impacts of Low Oxygen on Marine Life: Neglected, but a Crucial Priority for Research

AbstractGlobal ocean O₂ content has varied significantly across the eons, both shaping and being shaped by the evolutionary history of life on planet Earth. Indeed, past O₂ fluctuations have been associated with major extinctions and the reorganization of marine biota. Moreover, its most recent iteration-now anthropogenically driven-represents one of the most prominent challenges for both marine ecosystems and human societies, with ocean deoxygenation being regarded as one of the main drivers of global biodiversity loss. Yet ocean deoxygenation has received far less attention than concurrent environmental variables of marine climate change, namely, ocean warming and acidification, particularly in the field of experimental marine ecology. Together with the lack of consistent criteria defining gradual and acute changes in O₂ content, a general lack of multifactorial studies featuring all three drivers and their interactions prevents an adequate interpretation of the potential effects of extreme and gradual deoxygenation. We present a comprehensive overview of the interplay between O₂ and marine life across space and time and discuss the current knowledge gaps and future steps for deoxygenation research. This work may also contribute to the ongoing call for an integrative perspective on the combined effects of these three drivers of change for marine organisms and ecosystems worldwide.

Is Ocean Acidification Really a Threat to Marine Calcifiers? A Systematic Review and Meta-Analysis of 980+ Studies Spanning Two Decades

Ocean acidification is considered detrimental to marine calcifiers, but mounting contradictory evidence suggests a need to revisit this concept. This systematic review and meta-analysis aim to critically re-evaluate the prevailing paradigm of negative effects of ocean acidification on calcifiers. Based on 5153 observations from 985 studies, many calcifiers (e.g., echinoderms, crustaceans, and cephalopods) are found to be tolerant to near-future ocean acidification (pH ≈ 7.8 by the year 2100), but coccolithophores, calcifying algae, and corals appear to be sensitive. Calcifiers are generally more sensitive at the larval stage than adult stage. Over 70% of the observations in growth and calcification are non-negative, implying the acclimation capacity of many calcifiers to ocean acidification. This capacity can be mediated by phenotypic plasticity (e.g., physiological, mineralogical, structural, and molecular adjustments), transgenerational plasticity, increased food availability, or species interactions. The results suggest that the impacts of ocean acidification on calcifiers are less deleterious than initially thought as their adaptability has been underestimated. Therefore, in the forthcoming era of ocean acidification research, it is advocated that studying how marine organisms persist is as important as studying how they perish, and that future hypotheses and experimental designs are not constrained within the paradigm of negative effects.

Resilient consumers accelerate the plant decomposition in a naturally acidified seagrass ecosystem

Anthropogenic stressors are predicted to alter biodiversity and ecosystem functioning worldwide. However, scaling up from species to ecosystem responses poses a challenge, as species and functional groups can exhibit different capacities to adapt, acclimate, and compensate under changing environments. We used a naturally acidified seagrass ecosystem (the endemic Mediterranean Posidonia oceanica) as a model system to examine how ocean acidification (OA) modifies the community structure and functioning of plant detritivores, which play vital roles in the coastal nutrient cycling and food web dynamics. In seagrass beds associated with volcanic CO₂ vents (Ischia, Italy), we quantified the effects of OA on seagrass decomposition by deploying litterbags in three distinct pH zones (i.e., ambient, low, extreme low pH), which differed in the mean and variability of seawater pH. We replicated the study in two discrete vents for 117 days (litterbags sampled on day 5, 10, 28, 55, and 117). Acidification reduced seagrass detritivore richness and diversity through the loss of less abundant, pH-sensitive species but increased the abundance of the dominant detritivore (amphipod Gammarella fucicola). Such compensatory shifts in species abundance caused more than a threefold increase in the total detritivore abundance in lower pH zones. These community changes were associated with increased consumption (52%-112%) and decay of seagrass detritus (up to 67% faster decomposition rate for the slow-decaying, refractory detrital pool) under acidification. Seagrass detritus deployed in acidified zones showed increased N content and decreased C:N ratio, indicating that altered microbial activities under OA may have affected the decay process. The findings suggest that OA could restructure consumer assemblages and modify plant decomposition in blue carbon ecosystems, which may have important implications for carbon sequestration, nutrient recycling, and trophic transfer. Our study highlights the importance of within-community response variability and compensatory processes in modulating ecosystem functions under extreme global change scenarios.

Acclimation to low pH does not affect the thermal tolerance of Arbacia lixula progeny

As the ocean warms, the thermal tolerance of marine invertebrates is key to determining their distributional change, where acclimation to low pH may impact the thermal range of optimal development. We compared thermal tolerance of progeny from a low pH-acclimated sea urchin (Arbacia lixula) population from the CO₂ vents of Ischia (Italy) and a nearby population living at ambient pH. The percentages of normally developing gastrulae and two-armed larvae were determined across 10 temperatures representing present and future temperature conditions (16-34°C). Vent-acclimated sea urchins showed a greater percentage of normal development at 24 h, with a larger optimal developmental temperature range than control sea urchins (12.3°C versus 5.4°C range, respectively). At 48 h, upper lethal temperatures for 50% survival with respect to ambient temperatures were similar between control (+6.8°C) and vent (+6.2°C) populations. Thus, acclimation to low pH did not impact the broad thermal tolerance of A. lixula progeny. With A. lixula's barrens-forming abilities, its wide thermotolerance and its capacity to acclimate to low pH, this species will continue to be an important ecological engineer in Mediterranean macroalgal ecosystems in a changing ocean.

Niche breadth and biodiversity change derived from marine Amphipoda species off Iceland

Understanding the ecological requirements and thresholds of individual species is crucial to better predict potential outcomes of climate change on species distribution. In particular, species optima and lower and upper limits along resource gradients require attention. Based on Huisman‐Olff‐Fresco (HOF) models, we determined species‐specific responses along gradients of nine environmental parameters including depth in order to estimate niche attributes of 30 deep‐sea benthic amphipods occurring around Iceland. We, furthermore, examined the relationships between niche breadth, occupancy, and geographic range assuming that species with a wider niche are spatially more widely dispersed and vice versa. Overall, our results reveal that species react very differently to environmental gradients, which is independent of the family affiliation of the respective species. We could infer a strong relationship between occupancy and geographic range and also relate this to differences in niche breadth; that is specialist species with a narrow niche had a more limited distribution and may thus be more threatened by changing environmental conditions than generalist species, which are more widespread. Given the preponderance of rare species in the deep sea, this implies that many species could be at risk. However, this must be carefully weighed against geographical data gaps in this area, given that many deep‐sea areas are severely undersampled and the true distribution of most species is unknown. After all, our results underline that an accurate taxonomic classification is of crucial importance, without which ecological niche properties cannot be determined and which is hence fundamental for the assessment and understanding of changes in biodiversity in the face of increasing human perturbations.

Microplastics and bisphenol A hamper gonadal development of whiteleg shrimp (Litopenaeus vannamei) by interfering with metabolism and disrupting hormone regulation

Gonadal development is a prerequisite for the reproductive success of an organism, and might be affected by environmental factors such as emergent pollutants. Although marine crustaceans are threatened by ubiquitous emergent pollutants such as microplastics (MPs) and bisphenol A (BPA) under realistic scenarios, studies about the impacts of these pollutants on the gonadal development of crustacean species are rare. In this study, the effects of MPs and BPA, alone or in combination, on gonadal development were investigated in whiteleg shrimp (Litopenaeus vannamei). The results obtained demonstrated that whiteleg shrimp exposed to MPs and BPA had significantly smaller gonad-somatic index (GSI) and an obvious delay in the gonad developmental stage. In addition, exposure of whiteleg shrimp to pollutants tested resulted in a reduction in the oxygen consumption rate, elevation in the ammonia excretion rate, decline in the O: N ratio, and downregulation in the expression of metabolism-related genes, indicating significant disruptions of shrimp metabolism by the pollutants. Furthermore, in addition to a few exceptions, both the in vivo contents of gonadal development-related hormones (GIH and MIH) and the expression of genes encoding regulatory hormones (GIH, MIH, and CHH) were upregulated by the exposure of whiteleg shrimp to the pollutants investigated, suggesting a significant obstruction of endocrine regulation. Moreover, MP-BPA coexposure was shown to be more toxic to whiteleg shrimp than the corresponding single exposures and significantly greater amount of BPA accumulated in the gonads (both testis and ovaries) of shrimp with the coexistence of MPs, which may be caused by the Trojan horse effect and summation of the toxic impacts on common targets. In general, the data obtained in this study demonstrated that MPs and BPA at environmentally realistic concentrations significantly inhibited the gonadal development of whiteleg shrimp probably by interfering with metabolism and disrupting endocrine regulation.

Effects of ocean acidification on the biochemistry, physiology and parental transfer of Ampelisca brevicornis (Costa, 1853)

Ocean acidification (OA) has received more attention in the marine research community in recent years than any other topic. Excess carbon dioxide makes the ocean more acidic, threatening marine ecosystems. There has been little research on the impact of OA on crustaceans, particularly on their physiological and potential ecosystem-level consequences. Thus, we investigated the impacts of OA on the physiological and biochemical characteristics of the estuarine amphipod Ampelisca brevicornis. Ovigerous amphipods were harvested from nature and maintained in the laboratory to produce juveniles, which were then further reared to obtain the mature adults (F0) and successive offspring (F1). For this study, four pH treatments (pH 8.1, 7.5, 7.0, and 6.5) mimicking future OA were evaluated to understand the physiological and biochemical effects on the organisms. The findings of this study suggest that A. brevicornis is more vulnerable to OA than was previously established in short-term trials. The survival was significantly reduced as pH decreased over time and a significant interaction between pH and time was observed. Survival was higher in F1 than in F0 juveniles and vice versa in terms of growth. Animal's physiological responses such as growth, burrowing behavior, locomotor activity, swimming speed, ventilation rate and reproductive performance were negatively influenced by acidification. These physiological characteristics can be linked to the oxidative stress induced by global change conditions because excess of free radicals degrade cell functioning, affecting species' biochemical and physiological performance. These alterations may have long-term negative impacts, with ecological consequences. The results of this study provide baseline information regarding the effect of OA on this keystone crustacean that may be useful in simulating the impacts of OA to develop different conceptual models for a better understanding of the consequences and implications of climate change in the future for managing marine ecosystems.

Parental whole life cycle exposure modulates progeny responses to ocean acidification in slipper limpets

Multigenerational exposure is needed to assess the evolutionary potential of organisms in the rapidly changing seascape. Here, we investigate if there is a transgenerational effect of ocean acidification exposure on a calyptraeid gastropod such that long-term exposure elevates offspring resilience. Larvae from wild type Crepidula onyx adults were reared from hatching until sexual maturity for over 36 months under three pH conditions (pH 7.3, 7.7, and 8.0). While the survivorship, growth, and respiration rate of F₁ larvae were unaffected by acute ocean acidification (OA), long-term and whole life cycle exposure significantly compromised adult survivorship, growth, and reproductive output of the slipper limpets. When kept under low pH throughout their life cycle, only 6% of the F₁ slipper limpets survived pH 7.3 conditions after ~2.5 years and the number of larvae they released was ~10% of those released by the control. However, the F₂ progeny from adults kept under the long-term low pH condition hatched at a comparable size to those in medium and control pH conditions. More importantly, these F₂ progeny from low pH adults outperformed F₂ slipper limpets from control conditions; they had higher larval survivorship and growth, and reduced respiration rate across pH conditions, even at the extreme low pH of 7.0. The intragenerational negative consequences of OA during long-term acclimation highlights potential carryover effects and ontogenetic shifts in stress vulnerability, especially prior to and during reproduction. Yet, the presence of a transgenerational effect implies that this slipper limpet, which has been widely introduced along the West Pacific coasts, has the potential to adapt to rapid acidification.

Proteomics reveals sex-specific heat shock response of Baikal amphipod Eulimnogammarus cyaneus

The ancient Lake Baikal is the largest source of liquid freshwater on Earth and home to a unique fauna. Several hundred mostly cold-adapted endemic amphipod species inhabit Baikal, an ecosystem that is already being influenced by global change. In this study, we characterized the core proteome and heat stress-induced changes in a temperature-tolerant endemic amphipod, Eulimnogammarus cyaneus, using a proteogenomic approach (PRIDE dataset PXD013237) to unravel the molecular mechanisms of the observed adverse effects. As males were previously found to be much more tolerant to thermal stress, we placed special emphasis on differences between the sexes. For both sexes, we observed adaption of energy metabolism, cytoskeleton, lipid, and carbohydrate metabolism upon heat stress. In contrast, significant differences were determined in the molecular chaperone response. Females from the control conditions possessed significantly higher levels of heat shock proteins (HSP70, HSPb1, Hsc70-3), which, in contrast to males, were not further increased in response to heat stress. The inability of females to further increase heat shock protein synthesis in response to temperature stress may be due to sex-specific processes, such as egg production, requiring a large proportion of the available energy. As ovigerous females synthesize generally higher amounts of protein, they also need higher levels of molecular chaperones for the folding of these new proteins. Thus, the higher sensitivity of females to heat shock may be due to the lack of molecular chaperone molecules to counteract the heat-induced protein denaturation.

Long-term effects of elevated pCO2 levels on the expression of Chaoborus-induced defences in Daphnia pulex

Increased carbon dioxide from fossil fuel combustion results in an enrichment of CO₂ in the global carbon cycle. Recent evidence indicates that rising atmospheric CO₂ impacts the partial pressure of carbon dioxide (pCO₂) in freshwaters. This affects freshwater biota by disrupting chemical communication between predator and prey. One such well-described predator-prey interaction is the phantom midge larva Chaoborus preying on the freshwater crustacean Daphnia pulex. To counter Chaoborus predation, D. pulex develops defensive neckteeth in response to chemical cues. The strength of neckteeth expression is reduced when D. pulex experience elevated pCO₂ levels. This is discussed to directly impair predator perception and results in reduced defence expression. However, it is not known whether there are also long-term effects associated with continuous elevated pCO₂. Here, we investigated the effect of long-term exposure of D. pulex to elevated pCO₂ levels in a life-table experiment over three generations. Using a flow-through system, we continuously exposed D. pulex to cues released by the predatory larva Chaoborus and control or elevated pCO₂ levels. We determined morphological defence expression in the 2^nd juvenile instar and the number of neonates as a measure for life-history traits over three successive generations. We detected that elevated pCO₂ significantly reduces the expression of predator-induced morphological defences (i.e. neckteeth) and life-history parameters (i.e. number of neonates) in successive generations. Our data clearly show that at least three generations become more vulnerable to predation without indications of transgenerational acclimation. As Daphnia is a keystone grazer of freshwater ecosystems, this may destabilise population growth rates. In conclusion, long-term effects of pCO₂-induced reduction of predator-induced plasticity may significantly affect trophic interactions.

The anti-lipidemic drug simvastatin modifies epigenetic biomarkers in the amphipod Gammarus locusta

The adverse effects of certain environmental chemicals have been recently associated with the modulation of the epigenome. Although changes in the epigenetic signature have yet to be integrated into hazard and risk assessment, they are interesting candidates to link environmental exposures and altered phenotypes, since these changes may be passed across multiple non-exposed generations. Here, we addressed the effects of simvastatin (SIM), one of the most prescribed pharmaceuticals in the world, on epigenetic regulation using the amphipod Gammarus locusta as a proxy, to support its integration into hazard and environmental risk assessment. SIM is a known modulator of the epigenome in mammalian cell lines and has been reported to impact G. locusta ecological endpoints at environmentally relevant levels. G. locusta juveniles were exposed to three SIM environmentally relevant concentrations (0.32, 1.6 and 8 µg L^-1) for 15 days. Gene transcription levels of selected epigenetic regulators, i.e., dnmt1, dmap1, usp7, kat5 and uhrf1 were assessed, along with the quantification of DNA methylation levels and evaluation of key ecological endpoints: survival and growth. Exposure to 0.32 and 8 µg L^-1 SIM induced significant downregulation of DNA methyltransferase 1 (dnmt1), concomitant with global DNA hypomethylation and growth impacts. Overall, this work is the first to validate the basal expression of key epigenetic regulators in a keystone marine crustacean, supporting the integration of epigenetic biomarkers into hazard assessment frameworks.

Transgenerational acclimation to changes in ocean acidification in marine invertebrates

The rapid pace of increasing oceanic acidity poses a major threat to the fitness of the marine ecosystem, as well as the buffering capacity of the oceans. Disruption in chemical equilibrium in the ocean leads to decreased carbonate ion precipitation, resulting in calcium carbonate saturation. If these trends continue, calcifying invertebrates will experience difficultly maintaining their calcium carbonate exoskeleton and shells. Because malfunction of exoskeleton formation by calcifiers in response to ocean acidification (OA) will have non-canonical biological cascading results in the marine ecosystem, many studies have investigated the direct and indirect consequences of OA on ecosystem- and physiology-related traits of marine invertebrates. Considering that evolutionary adaptation to OA depends on the duration of OA effects, long-term exposure to OA stress over multi-generations may result in adaptive mechanisms that increase the potential fitness of marine invertebrates in response to OA. Transgenerational studies have the potential to elucidate the roles of acclimation, carryover effects, and evolutionary adaptation within and over generations in response to OA. In particular, understanding mechanisms of transgenerational responses (e.g., antioxidant responses, metabolic changes, epigenetic reprogramming) to changes in OA will enhance our understanding of marine invertebrate in response to rapid climate change.

Predator prey interactions between predatory gastropod Reishia clavigera, barnacle Amphibalanusamphitriteamphitrite and mussel Brachidontesvariabilis under ocean acidification

Since the response to ocean acidification is species specific, differences in responses between predator and prey will alter their interactions, hence affect the population dynamics of both species. Changes in predator prey interactions between a predatory muricid gastropod Reishia clavigera and its prey, the barnacle Amphibalanus amphitrite amphitrite and mussel Brachidontes variabilis under three pCO₂ levels (380, 950, and 1250 μatm) were investigated. The searching time for barnacles increased and the ability to locate them decreased at higher pCO₂ levels. The movement speed and the prey consumption rate, however, were independent of pCO₂. There was no preference towards either B. variabilis or A. amphitrite amphitrite regardless of pCO₂. Exposure experiments involving multiple generations are suggested to assess transgenerational effects of ocean acidification and the potential compensation responses before any realistic predictions on the long term changes of population dynamics of the interacting species can be made.

The effect of ocean acidification on the intertidal hermit crab Pagurus criniticornis is not modulated by cheliped amputation and sex

Impacts of the interactive effects of ocean acidification (OA) with other anthropogenic environmental stressors on marine biodiversity are receiving increasing attention in recent years. However, little is known about how organismal responses to OA may be influenced by common phenomena such as autotomy and sexual dimorphism. This study evaluated the long-term (120 days) combined effects of OA (pH 7.7), experimental cheliped amputation and sex on physiological stress (mortality, growth, number of molts, cheliped regeneration and startle response) and energy budget (lipid and calcium contents) in the intertidal sexually-dimorphic hermit crab Pagurus criniticornis. Crabs exposed to OA reduced survivorship (46%), molting frequency (36%) and lipid content (42%). Autotomised crabs and males molted more frequently (39% and 32%, respectively). Males presented higher regeneration (33%) and lower lipid content (24%). The few synergistic effects recorded did not indicate any clear pattern among treatments however, (1) a stronger reduction in lipid content was recorded in non-autotomised crabs exposed to low pH; (2) calcium content was higher in males than females only for autotomised crabs under control pH; and (3) autotomised females showed a proportionally slower activity recovery than autotomised males. Although our results suggest an effect of long-term exposure to low pH on the physiological stress and energy budget of Pagurus criniticornis, the physiological repertoire and plasticity associated with limb regeneration and the maintenance of dimorphism in secondary sexual characters may provide resilience to long-term exposure to OA.

Limitations of cross- and multigenerational plasticity for marine invertebrates faced with global climate change

Although cross generation (CGP) and multigenerational (MGP) plasticity have been identified as mechanisms of acclimation to global change, the weight of evidence indicates that parental conditioning over generations is not a panacea to rescue stress sensitivity in offspring. For many species, there were no benefits of parental conditioning. Even when improved performance was observed, this waned over time within a generation or across generations and fitness declined. CGP and MGP studies identified resilient species with stress tolerant genotypes in wild populations and selected family lines. Several bivalves possess favourable stress tolerance and phenotypically plastic traits potentially associated with genetic adaptation to life in habitats where they routinely experience temperature and/or acidification stress. These traits will be important to help 'climate proof' shellfish ventures. Species that are naturally stress tolerant and those that naturally experience a broad range of environmental conditions are good candidates to provide insights into the physiological and molecular mechanisms involved in CGP and MGP. It is challenging to conduct ecologically relevant global change experiments over the long times commensurate with the pace of changing climate. As a result, many studies present stressors in a shock-type exposure at rates much faster than projected scenarios. With more gradual stressor introduction over longer experimental durations and in context with conditions species are currently acclimatized and/or adapted to, the outcomes for sensitive species might differ. We highlight the importance to understand primordial germ cell development and the timing of gametogenesis with respect to stressor exposure. Although multigenerational exposure to global change stressors currently appears limited as a universal tool to rescue species in the face of changing climate, natural proxies of future conditions (upwelling zones, CO₂ vents, naturally warm habitats) show that phenotypic adjustment and/or beneficial genetic selection is possible for some species, indicating complex plasticity-adaptation interactions.

Does the antidepressant sertraline show chronic effects on aquatic invertebrates at environmentally relevant concentrations? A case study with the keystone amphipod, Gammarus locusta

The increasing use of Sertraline (SER) as antidepressant and its consequent presence in the aquatic environment is raising concern about the chronic effects of this pharmaceutical to aquatic organisms. As the current concentrations of SER in surface waters are typically in the low ng/L range, acute toxicity is unlikely to occur. However, prolonged exposure to low concentrations of SER may lead to sub-lethal effects in aquatic organisms, including alterations in important physiological functions like growth, reproduction, behaviour, and also in key biochemical processes, such as those associated with neurotransmission and redox balance. To test this hypothesis, we selected the amphipod Gammarus locusta, a keystone species used in ecotoxicological hazard assessment. In the present study, juveniles' G. locusta from a permanent laboratory culture were chronically exposed to low concentrations of SER (8-1000 ng/L) in a bioassay that lasted for 48 days, allowing for a life-cycle study including effects on reproduction. At the lowest SER concentrations with environmental relevance (8, 40 and 200 ng/L) we detected no significant changes in key ecological endpoints such as survival, growth, reproduction and movement behaviour, or in any of the biochemical markers analysed. However, at 1000 ng/L SER (a concentration one order of magnitude higher than the levels reported in aquatic environments) females showed a significant increase in movement versus control, whereas no activity changes were observed in males. Overall, these findings indicate that G. locusta females are potentially more susceptible to the chronic effects of SER. Moreover, the current environmental SER concentrations are unlikely to affect amphipod's ecological endpoints because only SER concentrations higher than the levels reported in aquatic environments produced effects on the behaviour of G. locusta females. However, the increasing consumption of SER, highlights the importance of monitoring its chronic risk to the aquatic wildlife.

Transgenerational exposure to ocean acidification induces biochemical distress in a keystone amphipod species (Gammarus locusta)

Atmospheric carbon dioxide (CO₂) levels are increasing at the fastest rate ever recorded, causing higher CO₂ dissolution in the ocean, leading to a process known as ocean acidification (OA). Unless anthropogenic CO₂ emissions are reduced, they are expected to reach ~900 ppm by the century's end, resulting in a 0.13-0.42 drop in the seawater pH levels. Since the transgenerational effects of high CO₂ in marine organisms are still poorly understood at lower levels of biological organization (namely at the biochemical level), here we reared a key ecological relevant marine amphipod, Gammarus locusta, under control and high CO₂ conditions for two generations. We measured several stress-related biochemical endpoints: i) oxidative damage [lipid peroxidation (LPO) and DNA damage]; ii) protein repair and removal mechanisms [heat shock proteins (HSPs) and ubiquitin (Ub)]; as well as iii) antioxidant responses [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione s-transferase (GST)] and total antioxidant capacity (TAC). The present results support the premise that exposure to high CO₂ is expected to decrease survival rates in this species and cause within- and transgenerational oxidative damage. More specifically, the predicted upsurge of reactive oxygen and nitrogen species seemed to overwhelm the stimulated amphipod antioxidant machinery, which proved insufficient in circumventing protein damage within the parents. Additionally, negative effects of OA are potentially being inherited by the offspring, since the oxidative stress imposed in the parent's proteome appears to be restricting DNA repair mechanisms efficiency within the offspring's. Thus, we argue that a transgenerational exposure of G. locusta could further increase vulnerability to OA and may endanger the fitness and sustainability of natural populations.