In coastal regions, sediment-dwelling animals are exposed to a high degree of variability in seawater and sediment pH and pH is expected to decline due to anthropogenic effects. The impacts of 6-week exposure to reduced-pH seawater on length, weight, and survival of two species of molluscs that inhabit mudflats, juvenile soft-shell clams (Mya arenaria) and adult mud snails (Tritia obsoleta), were examined in two laboratory trials (2017 and 2018). The interactive effects of this prior exposure to water column acidification and subsequent sediment acidification on burrowing behaviour were then investigated for these mollusc species and adults of the amphipod Corophium volutator. In a separate experiment, the potential involvement of GABAA receptors in changes in burrowing behaviour in reduced-pH conditions was tested by exposing three species: C. volutator, T. obsoleta, and the Baltic clam Limecola balthica to sediment acidification and the neuroinhibitor gabazine. Reduced-pH water conditions only decreased the shell length of T. obsoleta in 2017 while all other morphometric metrics were not significantly impacted for this species in either year or for M. arenaria. The burrowing of T. obsoleta was reduced by 13% in acidified sediments in one of the two years but not by prior exposure to water column acidification. The burrowing of M. arenaria was not affected by either factor. The burrowing of C. volutator was impacted by the interaction of water column exposure and sediment acidification in 2017 with the acidified water, control sediment treatment having 14% higher burrowing then the remaining treatment combinations. In 2018, C. volutator burrowing was reduced in acidified sediment by 30%. The presence of gabazine only had an interactive effect on the burrowing of one species, C. volutator. The presence of gabazine increased the proportion of C. volutator individuals burrowed in the acidified water treatment by almost 30%, suggesting that GABAA neuroreceptors are involved in the mechanism for the impact of sediment acidification on burrowing in this species. The results of our experiments indicate that there is taxonomic variation in species’ responses of benthic invertebrates to ocean and sediment acidification with respect to growth, survival, and burrowing behaviour.
Continue reading ‘Effects of sediment and water column acidification on growth, survival, burrowing behaviour, and GABAA receptor function of benthic invertebrates’Posts Tagged 'performance'
Effects of sediment and water column acidification on growth, survival, burrowing behaviour, and GABAA receptor function of benthic invertebrates
Published 16 June 2023 Science ClosedTags: biological response, laboratory, mollusks, morphology, mortality, performance, physiology, sediment
CO2-induced ocean acidification alters the burrowing behavior of Manila clam Ruditapes philippinarum by reversing GABAA receptor function
Published 12 June 2023 Science ClosedTags: biological response, laboratory, mesocosms, molecular biology, mollusks, performance, physiology, South Pacific
Biological burrowing behavior is an important driver shaping ecosystems that is being threatened by CO2-induced ocean acidification; however, the effects of ocean acidification on burrowing behavior and its neurological mechanism remain unclear. This study showed that elevated pCO2 significantly affected the burrowing behaviors of the Manila clam Ruditapes philippinarum, such as increased foot contraction, burrowing time, and intrabottom movement and decreased burrowing depth. Delving deeper into the mechanism, exposure to elevated pCO2 significantly decreased extracellular pH and increased [HCO3–]. Moreover, an indicator GABAA receptor, a neuroinhibitor for movement, was found to be closely associated with behavioral changes. In situ hybridization confirmed that the GABAA receptor was widely distributed in ganglia and foot muscles, and elevated pCO2 significantly increased the mRNA level and GABA concentration. However, the increase in GABAA receptor and its ligand did not suppress the foot movement, but rather sent “excitatory” signals for foot contraction. The destabilization of acid–base homeostasis was demonstrated to induce an increase in the reversal potential for GABAA receptor and an alteration in GABAA receptor function under elevated pCO2. This study revealed that elevated pCO2 affects the burrowing behavior of Manila clams by altering GABAA receptor function from inhibitory to excitatory.
Continue reading ‘CO2-induced ocean acidification alters the burrowing behavior of Manila clam Ruditapes philippinarum by reversing GABAA receptor function’The effects of ocean acidification on the olfactory system of fish
Published 9 June 2023 Science ClosedTags: biological response, fish, molecular biology, performance, physiology, review
High atmospheric carbon emissions from burning fossil fuels are responsible for rapid climate change. After reaching the ocean, the atmospheric carbon undergoes a chain of reactions and ultimately alters the chemistry of the ocean. The current trend is that pH levels are slowly decreasing resulting in a more acidic ocean. Research has focused on the effects of ocean acidification on marine calcifiers, as they will be directly impacted through the dissolution of their carbonate shells or skeleton. However, fish seem to be threatened by the disruption of their olfactory system. Olfaction is essential to many fish species as it allows them to navigate, find food, find mates for reproduction, find their habitats and avoid predators. Therefore, any impairment of the olfactory system could have serious consequences on an individual’s fitness and survival and have cascading effects at the ecosystem level. This essay discussed and reviewed the relevant literature focusing on answering the following research question: What are the mechanisms and the effects of ocean acidification on the olfactory system of fish and how can these effects be mitigated? This was done by answering the following three sub-questions: (a) What are the physiological mechanisms of ocean acidification on the olfaction of fish? (b) What are the sensory and behavioural effects caused by ocean acidification? (c) How can fish mitigate the effects of ocean acidification on their olfactory system?
Continue reading ‘The effects of ocean acidification on the olfactory system of fish’Microbial mats as model to decipher climate change effect on microbial communities through a mesocosm study
Published 7 June 2023 Science ClosedTags: adaptation, biological response, BRcommunity, community composition, laboratory, mesocosms, methods, multiple factors, otherprocess, performance, physiology, prokaryotes, temperature
Marine environments are expected to be one of the most affected ecosystems by climate change, notably with increasing ocean temperature and ocean acidification. In marine environments, microbial communities provide important ecosystem services ensuring biogeochemical cycles. They are threatened by the modification of environmental parameters induced by climate change that, in turn, affect their activities. Microbial mats, ensuring important ecosystem services in coastal areas, are well-organized communities of diverse microorganisms representing accurate microbial models. It is hypothesized that their microbial diversity and metabolic versatility will reveal various adaptation strategies in response to climate change. Thus, understanding how climate change affects microbial mats will provide valuable information on microbial behaviour and functioning in changed environment. Experimental ecology, based on mesocosm approaches, provides the opportunity to control physical-chemical parameters, as close as possible to those observed in the environment. The exposure of microbial mats to physical-chemical conditions mimicking the climate change predictions will help to decipher the modification of the microbial community structure and function in response to it. Here, we present how to expose microbial mats, following a mesocosm approach, to study the impact of climate change on microbial community.
Continue reading ‘Microbial mats as model to decipher climate change effect on microbial communities through a mesocosm study’The influence of upwelling on key bivalves from the Humboldt and Iberian current systems
Published 6 June 2023 Science ClosedTags: biological response, chemistry, field, mollusks, morphology, North Atlantic, performance, physiology, South Pacific
Eastern Boundary Upwelling Systems (EBUS) deliver cold, nutrient-rich waters, influencing coastal biota from the molecular to the ecosystem level. Although local upwelling (U) and downwelling (DU) conditions are often known, their influence on body attributes of relevant species has not been systematically compared within and between EBUS (i.e., below and above regional scales). Hence, we compared the physical-chemical characteristics of U and DU sites in the Humboldt Current system (Chile) and the Iberian Current system (Portugal). We then assessed the influence of U and DU upon eight body attributes in purple mussels (Perumytilus purpuratus) and Mediterranean mussels (Mytilus galloprovincialis), from the Humboldt and Iberian systems, respectively. We hypothesized that bivalves from U sites display better fitness, as measured by body attributes, regardless of their origin (EBUS). As expected, waters from U sites in both systems showed lower temperatures and pH, and higher nitrite concentrations. We also found that mussels from U sites showed better fitness than those in DU sites in 12 out of 16 direct U vs DU comparisons. Shell length, shell volume, organic content of soft-tissues, and mechanical properties of the shell averaged consistently higher in mussels from U sites in both Current systems. In addition, total weight, soft-tissue weight, shell weight and shell thickness were all higher in the U site at the Humboldt system but had less consistent differences at the Iberian system. Altogether, most results supported our working hypothesis and indicate that U conditions support better fitted mussels. The few attributes that did not exhibit the expected U vs DU differences in the Iberian system suggest that local and species-specific differences also play a role on the attributes of these species. These results may also serve as a reference point for further studies addressing the influence of upwelling in these productive, critically important systems.
Continue reading ‘The influence of upwelling on key bivalves from the Humboldt and Iberian current systems’Ocean acidification increases copper accumulation and exacerbates copper toxicity in Amphioctopus fangsiao (Mollusca: Cephalopoda): a potential threat to seafood safety
Published 31 May 2023 Science ClosedTags: biological response, growth, laboratory, metals, molecular biology, mollusks, morphology, multiple factors, North Pacific, performance, physiology
Highlights
- A. fangsiao can adapt well to ocean acidification after 21-days experiment.
- Copper accumulation in tissues showed increase in acidified seawater.
- Copper exposure can influence the growth and feeding of A. fangsiao.
- Acidification exacerbated the copper effect in metabolism and oxidative stress.
- Copper exposure triggered DNA and protein and mitochondrial damage.
Abstract
Ocean acidification (OA) and trace metal pollutants coexist to exert combined effects on the functions and services of marine ecosystems. Increasing atmospheric carbon dioxide has caused a decrease in the pH of the ocean, affecting the bioavailability and speciation of trace metals and consequently altering metal toxicity in marine organisms. As an important trace metal functioned in hemocyanin, the richness of Copper (Cu) in octopuses is remarkable. Therefore, the biomagnification and bioaccumulation capacities of Cu in octopuses may be a non-negligible risk of contamination. Here, Amphioctopus fangsiao was continuously exposed to acidified seawater (pH 7.8) and copper (50 μg/L) to investigate the combined effect of ocean acidification and Cu exposure on marine mollusks. Our results showed that A. fangsiao could adapt well to ocean acidification after 21 days of the rearing experiment. However, the accumulation of Cu in A. fangsiao intestine increased significantly in acidified seawater under high levels of Cu stress. In addition, Cu exposure can influence the physiological function of A. fangsiao, including growth and feeding. This study also demonstrated that Cu exposure disturbed glucolipid metabolism and induced oxidative damage to intestine tissue, and ocean acidification further exacerbated these toxic effects. The obvious histological damage and microbiota alterations were also caused by Cu stress and its combined effect with ocean acidification. At the transcription level, we found numerous differentially expressed genes (DEGs) and significantly enriched KEGG pathways, involving glycolipid metabolism, transmembrane transport, glucolipid metabolism, oxidative stress, mitochondrial, protein and DNA damage, all revealing the strong toxicological synergetic effect of Cu and OA exposure and the molecular adaptation mechanism of A. fangsiao. Collectively, this study demonstrated that octopuses may withstand future ocean acidification conditions, however, the complex interactions of future OA and trace metal pollution need to be emphasized. OA can influence the toxicity of trace metals, inducing a potential threat to marine organism safety.
Continue reading ‘Ocean acidification increases copper accumulation and exacerbates copper toxicity in Amphioctopus fangsiao (Mollusca: Cephalopoda): a potential threat to seafood safety’Effects of ocean acidification and ocean warming on the behavior and physiology of a subarctic, intertidal grazer
Published 24 May 2023 Science ClosedTags: biological response, laboratory, mollusks, multiple factors, performance, physiology, temperature
The global ocean is expected to both acidify and warm concurrently; thus, multiple-stressor manipulative experimentation is an emergent area of study that ultimately aims to examine the individual and interactive effects of these factors on marine organisms. We characterized the physiological responses to acidification and warming of the intertidal grazer Lottia scutum, and examined how these ocean change variables influenced predator-prey dynamics with Evasterias troschelii, a key sea star predator. Specifically, we conducted a laboratory experiment where we exposed limpets to factorial combinations of temperature (11 and 15°C) and pH (7.6 and 8.0), and measured effects on thermal tolerance, metabolic rate, cortisol concentrations, and behavioral responses to the predator. We found that ocean warming (OW) decreased the critical thermal maxima (CTmax) and increased cortisol levels in L. scutum, whereas ocean acidification (OA) increased the mass-specific metabolic rate in this species. Additionally, we found that there was no significant effect of OA or OW on the anti-predator behavior of L. scutum when exposed to E. troschelii. These results highlight the need for future studies to integrate multidisciplinary experimental designs (i.e. behavior and physiology) that span multiple levels of biological organization to make ecologically relevant predictions for how marine organisms will respond to ocean change.
Continue reading ‘Effects of ocean acidification and ocean warming on the behavior and physiology of a subarctic, intertidal grazer’Elevated water CO2 can prevent dietary-induced osteomalacia in post-smolt Atlantic salmon (Salmo salar, L.)
Published 24 May 2023 Science ClosedTags: biological response, fish, growth, laboratory, molecular biology, morphology, North Atlantic, performance, physiology
Expansion of land-based systems in fish farms elevate the content of metabolic carbon dioxide (CO2) in the water. High CO2 is suggested to increase the bone mineral content in Atlantic salmon (Salmo salar, L.). Conversely, low dietary phosphorus (P) halts bone mineralization. This study examines if high CO2 can counteract reduced bone mineralization imposed by low dietary P intake. Atlantic salmon post-seawater transfer (initial weight 207.03 g) were fed diets containing 6.3 g/kg (0.5P), 9.0 g/kg (1P), or 26.8 g/kg (3P) total P for 13 weeks. Atlantic salmon from all dietary P groups were reared in seawater which was not injected with CO2 and contained a regular CO2 level (5 mg/L) or in seawater with injected CO2 thus raising the level to 20 mg/L. Atlantic salmon were analyzed for blood chemistry, bone mineral content, vertebral centra deformities, mechanical properties, bone matrix alterations, expression of bone mineralization, and P metabolism-related genes. High CO2 and high P reduced Atlantic salmon growth and feed intake. High CO2 increased bone mineralization when dietary P was low. Atlantic salmon fed with a low P diet downregulated the fgf23 expression in bone cells indicating an increased renal phosphate reabsorption. The current results suggest that reduced dietary P could be sufficient to maintain bone mineralization under conditions of elevated CO2. This opens up a possibility for lowering the dietary P content under certain farming conditions.
Continue reading ‘Elevated water CO2 can prevent dietary-induced osteomalacia in post-smolt Atlantic salmon (Salmo salar, L.)’Long-term physiological responses to combined ocean acidification and warming show energetic trade-offs in an asterinid starfish
Published 22 May 2023 Science ClosedTags: biological response, calcification, echinoderms, laboratory, mortality, multiple factors, North Atlantic, performance, physiology, temperature
While organismal responses to climate change and ocean acidification are increasingly documented, longer-term (> a few weeks) experiments with marine organisms are still sparse. However, such experiments are crucial for assessing potential acclimatization mechanisms, as well as predicting species-specific responses to environmental change. Here, we assess the combined effects of elevated pCO2 and temperature on organismal metabolism, mortality, righting activity, and calcification of the coral reef-associated starfish Aquilonastra yairi. Specimens were incubated at two temperature levels (27 °C and 32 °C) crossed with three pCO2 regimes (455 µatm, 1052 µatm, and 2066 µatm) for 90 days. At the end of the experiment, mortality was not altered by temperature and pCO2 treatments. Elevated temperature alone increased metabolic rate, accelerated righting activity, and caused a decline in calcification rate, while high pCO2 increased metabolic rate and reduced calcification rate, but did not affect the righting activity. We document that temperature is the main stressor regulating starfish physiology. However, the combination of high temperature and high pCO2 showed nonlinear and potentially synergistic effects on organismal physiology (e.g., metabolic rate), where the elevated temperature allowed the starfish to better cope with the adverse effect of high pCO2 concentration (low pH) on calcification and reduced skeletal dissolution (antagonistic interactive effects) interpreted as a result of energetic trade-offs.
Continue reading ‘Long-term physiological responses to combined ocean acidification and warming show energetic trade-offs in an asterinid starfish’Evidence for an effective defence against ocean acidification in the key bioindicator pteropod Limacina helicina
Published 19 May 2023 Science ClosedTags: biological response, dissolution, laboratory, mollusks, morphology, mortality, North Pacific, performance, zooplankton
The pteropod Limacina helicina has become an important bioindicator species for the negative impacts of ocean acidification (OA) on marine ecosystems. However, pteropods diversified during earlier high CO2 periods in Earth history and currently inhabit regions that are naturally corrosive to their shells, suggesting that they possess mechanisms to survive unfavourable conditions. Recent work, which is still under considerable debate, has proposed that the periostracum, a thin organic coating on the outer shell, protects pteropods from shell dissolution. Here, we provide direct evidence that shows that damage to the L. helicina periostracum results in dissolution of the underlying shell when exposed to corrosive water for ∼8 d, while an intact periostracum protects the shell from dissolution under the same conditions. This important first line of defence suggests that pteropods are more resistant to OA-induced shell dissolution than is generally accepted.
Continue reading ‘Evidence for an effective defence against ocean acidification in the key bioindicator pteropod Limacina helicina’Recalibrating the significance of the decline effect in fish ocean acidification research
Published 16 May 2023 Science ClosedTags: biological response, fish, performance, review
The recently described decline effect in ocean acidification impacts on fish behaviour should not be equated with negligible effects. Here, existing mechanistic data are used to argue for continued research and cautions against “throwing the baby out with the bathwater.”
The past few years have seen a seismic shift in the scientific consensus of ocean acidification and its impacts on fishes, particularly the adverse effects on behaviour. Foundational early work on coral reef fishes detailed olfactory disturbances that left fish unable to detect or discriminate predator cues and necessary habitat settlement cues—both of which were held up as potentially serious consequences of ocean acidification that may threaten global fish populations [1]. A decade later, Clark and colleagues published a rigorous follow-up that questioned the reproducibility of the early work on fish behaviour [2], and while several design aspects were disputed [3], the prevailing opinions on the behavioural effects of ocean acidification on fishes began to change. The recently published meta-analysis by Clements and colleagues [4] reinforced this shift by demonstrating a decline in effect size response ratios over time in studies exploring the impacts of ocean acidification on fish behaviour. The authors argued that ocean acidification has negligible effects on fish behaviour. More alarming was the determination that a University investigative panel concluded that a prominent author of the early ocean acidification studies committed scientific misconduct in the form of data fabrication and falsification [5]. This has led to one retraction of a high-impact work on coral reef fishes, although as of this writing, no ocean acidification papers have been retracted nor any expressions of concern been issued. Nonetheless, guilt by association has coloured the field of ocean acidification and fish behaviour. Despite all of this, I would urge the scientific community to remember the classic idiom and not “throw the baby out with the bathwater”.
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Continue reading ‘Recalibrating the significance of the decline effect in fish ocean acidification research’Ocean acidification alters foraging behaviour in Dungeness crab through impairment of the olfactory pathway
Published 12 May 2023 Science ClosedTags: biological response, crustaceans, laboratory, morphology, North Pacific, performance, physiology
Crustacean olfaction is fundamental to most aspects of living and communicating in aquatic environments and more broadly, for individual- and population-level success. Accelerated ocean acidification from elevated CO2 threatens the ability of crabs to detect and respond to important olfactory-related cues. Here, we demonstrate that the ecologically and economically important Dungeness crab (Metacarcinus magister) exhibits reduced olfactory-related antennular flicking responses to a food cue when exposed to near-future CO2 levels, adding to the growing body of evidence of impaired crab behaviour. Underlying this altered behaviour, we find that crabs have lower olfactory nerve sensitivities (twofold reduction in antennular nerve activity) in response to a food cue when exposed to elevated CO2. This suggests that near-future CO2 levels will impact the threshold of detection of food by crabs. We also show that lower olfactory nerve sensitivity in elevated CO2 is accompanied by a decrease in the olfactory sensory neuron (OSN) expression of a principal chemosensory receptor protein, ionotropic receptor 25a (IR25a) which is fundamental for odorant coding and olfactory signalling cascades. The OSNs also exhibit morphological changes in the form of decreased surface areas of their somata. This study provides the first evidence of the effects of high CO2 levels at multiple levels of biological organization in marine crabs, linking physiological and cellular changes with whole animal behavioural responses.
Continue reading ‘Ocean acidification alters foraging behaviour in Dungeness crab through impairment of the olfactory pathway’The effects of the “deadly trio” (warming, acidification, and deoxygenation) on fish early ontogeny
Published 11 May 2023 Science ClosedTags: biological response, fish, laboratory, morphology, mortality, multiple factors, North Atlantic, oxygen, performance, physiology, reproduction, temperature
The interaction between increased dissolved carbon dioxide, rising temperatures, and oxygen loss – the so-called “deadly trio” – is expected to strongly affect marine biota over the coming years, potentially undermining ocean services and uses. Nonetheless, no study has so far scrutinized the cumulative impact of these three stressors on fish embryonic and larval stages, known to be particularly vulnerable to environmental stress. To fill this knowledge gap, we implemented a fully multi-factorial design to investigate the effects of acute warming (Δ + 4°C; 22 ºC), acidification (Δ − 0.4 pH units; ~ 7.7 pCO2) and deoxygenation (Δ − 60% O2 saturation, ~ 3 mg O2 l− 1) over a comprehensive array of physiological (hatching success, survival rates, deformities rates, and heart rates) and behavioural responses (larvae responsiveness and phototaxis) across the early ontogeny of the temperate gilthead seabream (Sparus aurata). Deoxygenation was the main driver of negative impacts in the hatching success (64.25%), survival (46.71%), and heart rates (31.99%) of recently hatched larvae, being generally further exacerbated when warming and acidification co-occurred. On the other hand, acidification was the only factor to induce a significant decrease in the proportion of phototactic behaviour (50%). The behavioural and physiological responses showed to be highly correlated across experimental treatments, specifically, phototaxis was negatively correlated with the incidence of malformations, and positively correlated with heart rates. Overall, our findings indicate that the interaction between warming, acidification, and deoxygenation is markedly detrimental to fish early developmental stages, impacting several key features at this critical life stage that may eventually cause adverse carry-over effects. Importantly, our analysis highlights the need to assess the concurrent impacts of stressors’ interaction on marine taxa to better predict future ecosystem responses to ocean changes.
Continue reading ‘The effects of the “deadly trio” (warming, acidification, and deoxygenation) on fish early ontogeny’Effects of dissolved carbon dioxide on growth and vertebral column of hybrid marine grouper (Epinephelus fuscoguttatus × E. lanceolatus) early advanced larvae
Published 24 April 2023 Science ClosedTags: biological response, fish, growth, laboratory, morphology, mortality, performance, physiology, South Pacific
Highlights
- Ocean acidification negatively impacted the early advanced larvae of the marine hybrid tiger grouper × giant grouper (TG × GG).
- Worst growth, survival, weight, food consumption, and conversion rates at 1000 ppm CO2.
- Deformed vertebral columns were observed at 1000 ppm CO2, while normal vertebral column observed at 400 ppm CO2.
- This study provides guidelines for future studies on TG × GG larvae or other marine fish larvae under elevated CO2 concentrations.
Abstract
This study investigated the effects of different dissolved carbon dioxide (CO2) concentrations (400, 700, and 1000 ppm) on the growth and vertebral column formation of hybrid tiger grouper × giant grouper (TG × GG) in their advanced larval stage under controlled laboratory conditions for 12 weeks. Growth parameters, including specific growth rate (SGR), survival rate, food consumption (FC), and food conversion rate (FCR), were calculated at the end of the experiment. Vertebral column formation was analysed using X-radiography and osteology methods. The results showed that all growth parameters were significantly affected by CO2 concentration, with the best performances observed under 400 ppm CO2. The highest statistically significant (p < 0.05) SGR, survival rate, and FC were observed under 400 ppm CO2, whereas the lowest was observed under 1000 ppm CO2. The lowest FCR (0.40, p < 0.05) was observed in 400 ppm CO2 and the highest was observed at 1000 ppm CO2 (0.59, p < 0.05). Furthermore, larvae without vertebral column malformations were observed in 400 ppm CO2, while larvae with small angles of kyphosis were observed in 700 ppm CO2, and larvae with kyphosis, lordosis, and vertebral compression were observed in 1000 ppm CO2. Only six spine measurements out of 31 obtained under different CO2 concentrations were significantly different (p < 0.05). Overall, the results suggest that CO2 concentration plays a crucial role in the growth and vertebral column formation of TG × GG in their advanced larval stage. The optimal CO2 concentration for the aquaculture of TG × GG in their advanced larval stage was found to be 400 ppm or lower. This study highlights the importance of maintaining optimal CO2 concentrations to enhance the growth and health of fish in aquaculture systems…
Continue reading ‘Effects of dissolved carbon dioxide on growth and vertebral column of hybrid marine grouper (Epinephelus fuscoguttatus × E. lanceolatus) early advanced larvae’From marine snails to marine spatial planning : the science of human impacts and relationships with marine ecosystems
Published 20 April 2023 Science ClosedTags: biological response, BRcommunity, calcification, growth, mortality, multiple factors, performance, physiology, reproduction, review, temperature
Extractive human systems are driving unprecedented biodiversity loss and exacerbating social inequity. The magnitude of the intertwined climate, biodiversity, and social inequity crises has prompted the development of interdisciplinary research approaches to address these complex problems. One such approach, social-ecological systems (SES), aims to understand the relationships between coupled human and ecological systems. This thesis applies an SES lens to understand the science of human impacts on and relationships with marine ecosystems and inform characterizations of system vulnerability. First, I examined the sensitivity of marine ectothermic animals to climate change by conducting a meta-analysis of the effects of ocean acidification and warming. My synthesis of nearly five hundred factorial studies demonstrates the negative effects of these two drivers, identifies specific taxonomic groups (molluscs), life- history traits (adults, sessile), and latitudes (tropical and temperate) that are more sensitive, and refutes two common assumptions about the drivers’ interactive effects. Next, I tested whether populations of a marine snail vary in their vulnerability to ocean warming based on thermal sensitivity and local rates of ocean warming. Using coupled lab and field experiments with snails from two regions in the middle of their range that differ in thermal characteristics, I found that snails from the warmer Salish Sea, an urban sea, showed greater vulnerability to ocean warming than those from the cooler central coast of British Columbia, Canada. Finally, to inform how humans can mitigate our impacts while sustaining complex relationships with the ocean, I partnered with the Sḵwx̲wú7mesh Úxwumixw (Squamish Nation) and regional stewardship organizations on a marine spatial planning project in the Salish Sea. I employed a mixed- methods community-based participatory mapping approach to characterize place-based values and outline opportunities to decolonize research and mapping processes. The results contribute important social data about place-based values, reveal value interactions, reflect knowledge system plurality, and identify avenues to advance reconciliation. Overall, this thesis highlights the vulnerability of marine life, particularly life within urban seas, to climate change and provides a roadmap for researchers and decision-makers to meaningfully steward the health and well-being of coastal social-ecological systems.
Continue reading ‘From marine snails to marine spatial planning : the science of human impacts and relationships with marine ecosystems’How ocean warming and acidification affect the life cycle of six worldwide commercialised sea urchin species: a review
Published 19 April 2023 Science ClosedTags: abundance, adaptation, Arctic, biological response, echinoderms, Mediterranean, morphology, mortality, multiple factors, North Pacific, otherprocess, performance, physiology, reproduction, review, South Pacific, temperature
Ongoing global changes are expected to affect the worldwide production of many fisheries and aquaculture systems. Because invertebrates represent a relevant industry, it is crucial to anticipate challenges that are resulting from the current environmental alterations. In this review, we rely on the estimated physiological limits of six commercialised species of sea urchins (Loxechinus albus, Mesocentrotus franciscanus, Paracentrotus lividus, Strongylocentrotus droebachiensis, Strongylocentrotus intermedius and Strongylocentrotus purpuratus) to define the vulnerability (or resilience) of their populations facing ocean warming and acidification (OW&A). Considering that coastal systems do not change uniformly and that the populations’ response to stressors varies depending on their origin, we investigate the effects of OW&A by including studies that estimate future environmental mutations within their distribution areas. Cross-referencing 79 studies, we find that several sea urchin populations are potentially vulnerable to the predicted OW&A as environmental conditions in certain regions are expected to shift beyond their estimated physiological limit of tolerance. Specifically, while upper thermal thresholds seem to be respected for L. albus along the SW American coast, M. franciscanus and S. purpuratus southern populations appear to be vulnerable in NW America. Moreover, as a result of the strong warming expected in the Arctic and sub-Arctic regions, the local productivity of S. droebachiensis is also potentially largely affected. Finally, populations of S. intermedius and P. lividus found in northern Japan and eastern Mediterranean respectively, are supposed to decline due to large environmental changes brought about by OW&A. This review highlights the status and the potential of local adaptation of a number of sea urchin populations in response to changing environmental conditions, revealing possible future challenges for various local fishing industries.
Continue reading ‘How ocean warming and acidification affect the life cycle of six worldwide commercialised sea urchin species: a review’Combined effects of climate change and BDE-209 dietary exposure on the behavioural response of the white seabream, Diplodus sargus
Published 14 April 2023 Science ClosedTags: biological response, fish, laboratory, multiple factors, performance, temperature, toxicants
Highlights
- Fish were exposed to acidification, warming and BDE-209 via diet for 56 days.
- BDE-209 lowered fish awareness of a risky situation and increased fish activity.
- Interaction of BDE-209 with acidification and/or warming altered fish responses.
- Acidification plus BDE-209 exposure increased fish anxiety and shoal cohesion.
- Warming plus BDE-209 exposure increased anxiety and reversed fish lateralization.
Abstract
Decabromodiphenyl-ether (BDE-209) is a persistent organic pollutant ubiquitously found in marine environments worldwide. Even though this emerging chemical contaminant is described as highly toxic, bioaccumulative and biomagnifiable, limited studies have addressed the ecotoxicological implications associated with its exposure in non-target marine organisms, particularly from a behavioural standpoint. Alongside, seawater acidification and warming have been intensifying their impacts on marine ecosystems over the years, compromising species welfare and survival. BDE-209 exposure as well as seawater acidification and warming are known to affect fish behaviour, but information regarding their interactive effects is not available. In this study, long-term effects of BDE-209 contamination, seawater acidification and warming were studied on different behavioural traits of Diplodus sargus juveniles. Our results showed that D. sargus exhibited a marked sensitivity in all the behaviour responses after dietary exposure to BDE-209. Fish exposed to BDE-209 alone revealed lower awareness of a risky situation, increased activity, less time spent within the shoal, and reversed lateralization when compared to fish from the Control treatment. However, when acidification and/or warming were added to the equation, behavioural patterns were overall altered. Fish exposed to acidification alone exhibited increased anxiety, being less active, spending more time within the shoal, while presenting a reversed lateralization. Finally, fish exposed to warming alone were more anxious and spent more time within the shoal compared to those of the Control treatment. These novel findings not only confirm the neurotoxicological attributes of brominated flame retardants (like BDE-209), but also highlight the relevance of accounting for the effects of abiotic variables (e.g. pH and seawater temperature) when investigating the impacts of environmental contaminants on marine life.
Continue reading ‘Combined effects of climate change and BDE-209 dietary exposure on the behavioural response of the white seabream, Diplodus sargus’The impact of ocean acidification on the eye, cuttlebone and behaviors of juvenile cuttlefish (Sepiella inermis)
Published 12 April 2023 Science ClosedTags: biological response, laboratory, mollusks, performance, physiology
The cuttlefish (Sepiella inermis) is an economically important species in the coastal seas of China. The impacts of ocean acidification on the ability of juvenile cuttlefish to select a suitable habitat, its hunting and swimming behavior, remains unknown. We examined behavior-related responses and the eye and cuttlebone structure of juvenile cuttlefish following short-term exposure to CO2-enriched seawater. The predation success rate decreased with the elevation in CO2 concentration. In the CO2 treatment groups, cuttlefish spent more time in the dark zone and the average swimming speed and total swimming distance significantly decreased. The structure of the retina and cuttlebone was affected by seawater acidification. Moreover, apoptotic cells were significantly increased in the eyes. In the wild, the impairment of the eye and cuttlebone may decrease the predation ability of juvenile cuttlefish and negatively affect their ability to select a suitable habitat, which would be detrimental to its population.
Continue reading ‘The impact of ocean acidification on the eye, cuttlebone and behaviors of juvenile cuttlefish (Sepiella inermis)’Increased food resources help eastern oyster mitigate the negative impacts of coastal acidification
Published 11 April 2023 Science ClosedTags: adaptation, biological response, growth, laboratory, mollusks, mortality, multiple factors, nutrients, otherprocess, performance, physiology, respiration
Oceanic absorption of atmospheric CO2 results in alterations of carbonate chemistry, a process coined ocean acidification (OA). The economically and ecologically important eastern oyster (Crassostrea virginica) is vulnerable to these changes because low pH hampers CaCO3 precipitation needed for shell formation. Organisms have a range of physiological mechanisms to cope with altered carbonate chemistry; however, these processes can be energetically expensive and necessitate energy reallocation. Here, the hypothesis that resilience to low pH is related to energy resources was tested. In laboratory experiments, oysters were reared or maintained at ambient (400 ppm) and elevated (1300 ppm) pCO2 levels during larval and adult stages, respectively, before the effect of acidification on metabolism was evaluated. Results showed that oysters exposed to elevated pCO2 had significantly greater respiration. Subsequent experiments evaluated if food abundance influences oyster response to elevated pCO2. Under high food and elevated pCO2 conditions, oysters had less mortality and grew larger, suggesting that food can offset adverse impacts of elevated pCO2, while low food exacerbates the negative effects. Results also demonstrated that OA induced an increase in oyster ability to select their food particles, likely representing an adaptive strategy to enhance energy gains. While oysters appeared to have mechanisms conferring resilience to elevated pCO2, these came at the cost of depleting energy stores, which can limit the available energy for other physiological processes. Taken together, these results show that resilience to OA is at least partially dependent on energy availability, and oysters can enhance their tolerance to adverse conditions under optimal feeding regimes.
Continue reading ‘Increased food resources help eastern oyster mitigate the negative impacts of coastal acidification’Effects of ocean acidification on dopamine-mediated behavioral responses of a coral reef damselfish
Published 6 April 2023 Science ClosedTags: biological response, fish, laboratory, North Atlantic, performance, physiology
Highlights
- CO2-induced ocean acidification (OA) altered dopamine-mediated fish behavior.
- The dopamine D1-receptor agonist SKF 38393 increased anxiety in control fish.
- OA-exposed fish exhibited maximally measurable anxiety levels.
- CO2/pH measured in reef crevasses used as fish shelters were similar to OA tested here.
- The implications of OA on fish fitness should be assessed through future studies.
Abstract
We investigated whether CO2-induced ocean acidification (OA) affects dopamine receptor-dependent behavior in bicolor damselfish (Stegastes partitus). Damselfish were kept in aquaria receiving flow through control (pH ~ 8.03; pCO2 ~ 384 μatm) or OA (pH ~ 7.64; CO2 ~ 1100 μatm) seawater at a rate of 1 L min−1. Despite this relatively fast flow rate, fish respiration further acidified the seawater in both control (pH ~7.88; pCO2 ~ 595 μatm) and OA (pH ~7.55; pCO2 ~ 1450 μatm) fish-holding aquaria. After five days of exposure, damselfish locomotion, boldness, anxiety, and aggression were assessed using a battery of behavioral tests using automated video analysis. Two days later, these tests were repeated following application of the dopamine D1 receptor agonist SKF 38393. OA-exposure induced ceiling anxiety levels that were significantly higher than in control damselfish, and SKF 38393 increased anxiety in control damselfish to a level not significantly different than that of OA-exposed damselfish. Additionally, SKF 38393 decreased locomotion and increased boldness in control damselfish but had no effect in OA-exposed damselfish, suggesting an alteration in activity of dopaminergic pathways that regulate behavior under OA conditions. These results indicate that changes in dopamine D1 receptor function affects fish behavior during exposure to OA. However, subsequent measurements of seawater sampled using syringes during the daytime (~3–4 pm local time) from crevasses in coral reef colonies, which are used as shelter by damselfish, revealed an average pH of 7.73 ± 0.03 and pCO2 of 925.8 ± 62.2 μatm; levels which are comparable to Representative Concentration Pathway (RCP) 8.5 predicted end-of-century mean OA levels in the open ocean. Further studies considering the immediate environmental conditions experienced by fish as well as individual variability and effect size are required to understand potential implications of the observed OA-induced behavioral effects on damselfish fitness in the wild.
Continue reading ‘Effects of ocean acidification on dopamine-mediated behavioral responses of a coral reef damselfish’
