Healthy ecosystems and species have some degree of resilience to changing conditions, however as the frequency and severity of environmental changes increase, resilience may be diminished or lost. In Sweden, one example of a species with reduced resilience is the Atlantic cod (Gadus morhua). This species has been subjected to overfishing, and with additional pressures such as habitat degradation and changing environmental conditions there has been little to no recovery, despite more than a decade of management actions. Given the historical ecological, economical, and cultural significance of cod, it is important to understand how Atlantic cod respond to global climate change to recover and sustainably manage this species in the future. A multi-stressor experiment was conducted to evaluate physiological responses of juvenile cod exposed to warming, ocean acidification, and freshening, changes expected to occur in their nursery habitat. The response to single drivers showed variable effects related to fish biometrics and increased levels of oxidative stress dependent parameters. Importantly, two separate responses were seen within a single treatment for the multi-stressor and freshening groups. These within-treatment differences were correlated to genotype, with the offshore ecotype having a heightened stress response compared to the coastal ecotype, which may be better adapted to tolerate future changes. These results demonstrate that, while Atlantic cod have some tolerance for future changes, ecotypes respond differently, and cumulative effects of multiple stressors may lead to deleterious effects for this important species.
Continue reading ‘Physiological responses of Atlantic cod to climate change indicate that coastal ecotypes may be better adapted to tolerate ocean stressors’Posts Tagged 'performance'
Physiological responses of Atlantic cod to climate change indicate that coastal ecotypes may be better adapted to tolerate ocean stressors
Published 7 June 2024 Science ClosedTags: biological response, chemistry, fish, laboratory, morphology, multiple factors, North Atlantic, performance, physiology, respiration, salinity, temperature
Lower seawater pH reduces the foraging activity of the Florida stone crab, Menippe mercenaria (Say, 1818) (Decapoda: Brachyura: Menippidae)
Published 3 June 2024 Science ClosedTags: biological response, chemistry, crustaceans, laboratory, North Atlantic, performance, physiology
Anthropogenic activities like habitat degradation, excess nutrient runoff, and sewage outfalls can decrease seawater pH in coastal environments. Coastal waters can also experience frequent fluctuations in seawater pH due to biological activity (i.e., photosynthesis and respiration). Commercially important species like the Florida stone crab, Menippe mercenaria (Say, 1818), inhabit coastal waters and experience fluctuations in seawater pH on both diurnal and seasonal scales. Organisms exposed to reductions in seawater pH may have difficulty sensing chemical cues due to physiological changes and the associated metabolic stress of compensating for a more acidic environment. Here we determined the foraging activity of the Florida stone crab when exposed to reduced pH conditions (control pH 7.8, reduced pH 7.6). The impacts of reduced pH on foraging activity were determined by monitoring activity time, stress, predation attempts, and handling time when crabs were exposed to lower seawater pH for 12 hrs. Crabs exposed to reduced pH conditions experienced elevated stress levels and reduced activity than crabs in the control pH treatment. These results suggest that exposure to more extreme pH conditions may limit the foraging activity of stone crabs.
Continue reading ‘Lower seawater pH reduces the foraging activity of the Florida stone crab, Menippe mercenaria (Say, 1818) (Decapoda: Brachyura: Menippidae)’Growth, photosynthetic and nutrition characteristics of Pyropia haitanensis in response to the effects of increased CO2 and chloramphenicol
Published 27 May 2024 Science ClosedTags: algae, biological response, chemistry, laboratory, multiple factors, North Pacific, performance, photosynthesis, physiology, toxicants
Pyropia haitanensis was cultured under two CO2 (410 (LC), 1000 (HC) μL L-1) concentrations and six chloramphenicol (CAP)-methanol solutions (0, 0+methanol, 10, 50, 100, 250 μg mL-1) to investigate the effects of elevated CO2 and CAP on its growth, photosynthesis and biochemical characteristics. HC had no obvious effects on the growth rate (RGR) with CAP in the range of 10 to 100 μg mL-1, but the decrease of RGR by HC was statistically significant with the CAP dosage at 250 μg mL-1. HC had no significant effect on net photosynthetic rates (Pn) in the present of CAP (10-250 μg mL-1). CAP greatly reduced net photosynthesis as well as the maximal photochemical yield (Fv/Fm) and photosynthetic efficiency (αETR). In contrast, the maximum relative electron transport rates (rETRm) were almost constant with the CAP dosage from 10 to 100 μg mL-1. HC significantly increased the energy fluxes (per RC) for absorption (ABS/RC), trapping (TRo/RC) and transport fluxes (ETo/RC) with the dosage of CAP at 250 μg mL-1. Principal component analysis (PCA) indicated that CAP was positively correlated with the synthesis of free amino acids (FAA), contents of umami-, sweet- and essential AA were significantly enhanced with the interaction of HC and higher CAP dosage at 100 μg mL-1, which led to the variation of flavor in algae. Furthermore, phycobiliproteins and soluble protein (SP) contents were remarkably reduced by CAP. Contents of chlorophyll a (Chl a), carotenoids (Car), soluble carbohydrates (SC) and C/N ratios were almost unchanged among treatments. The study indicates that future ocean acidification has no obvious effects on the biomass productivity of P. haitanensis, maintained steady photosynthetic activities with the CAP (within 100 μg mL-1) and induces better flavor. The data obtained have important theoretical relevance for in-depth understanding of algal responses to global changes and oceanic contamination.
Continue reading ‘Growth, photosynthetic and nutrition characteristics of Pyropia haitanensis in response to the effects of increased CO2 and chloramphenicol’Important but ignored: research progress on crab foraging behaviour and its implications for aquaculture
Published 24 May 2024 Science ClosedTags: biological response, crustaceans, fisheries, performance, review
Crab fisheries play a crucial role in global fishery economics, but they heavily rely on wild catches. With the decline and exploratory limits of wild populations, expanding the scale and production of aquaculture becomes vital for the sustainability of crab fisheries. The development of crab aquaculture encounters significant dietary challenges, stemming from suboptimal formulated feeds and inefficient feeding management. Leveraging insights from crab foraging behaviours offers a promising solution to these issues; however, progress is hindered by a lack of comprehensive behavioural data and the underappreciation of these insights in aquaculture. To bridge this gap, we systematically examine the progress in studies of crab foraging behaviour, analysing the influences of predators, prey, and environmental characteristics, and discuss possibilities for future research and development in the field by combining these findings with the demands of aquaculture. This review identifies a discrepancy in research focus, with inadequate emphasis on the major cultured species and their behavioural responses to factors limiting aquaculture productivity, aiming to enhance our comprehension of crab foraging behaviour and facilitate growth in the crab industry.
Continue reading ‘Important but ignored: research progress on crab foraging behaviour and its implications for aquaculture’Living under natural conditions of ocean acidification entails energy expenditure and oxidative stress in a mussel species
Published 13 May 2024 Science ClosedTags: biological response, chemistry, laboratory, Mediterranean, mollusks, morphology, performance, physiology, vents
Highlights
- First investigation of Mytilus galloprovincialis from the CO2 vents of Castello Aragonese
- Strong corrosion of valves in organisms living at lower pH
- Content of amino acids, nucleotides, lipids and organic osmolytes reduced at lower pH
- No significant effects on most biochemical parameters in relation to pH variation
- Energy expenditure underpinning survival under acidified conditions
Abstract
We investigated the health conditions of the Mediterranean mussel Mytilus galloprovincialis recruited in the CO2 vents system of Castello Aragonese at Ischia Island (Mediterranean Sea). Individuals of M. galloprovincialis were sampled in three sites along the pH gradient (8.10, 7.7 and up to <7.4). Untargeted metabolomics and biochemical endpoints related to energetic metabolism, oxidative stress/damage, neurotoxicity and immune defense were analyzed. Corrosion of the valves occurred at low pH. A separation of the metabolome was observed along the pH gradient. Metabolites belonging to amino acids, nucleosides, lipids and organic osmolytes were significantly reduced in the organisms from the most acidified sites. The content of reactive oxygen species and the activity of glutathione peroxidase were reduced in organisms from the acidified sites compared to ambient pH, and no oxidative damage was induced. Overall results suggested the presence of an energy cost underpinning long-term survival in acidified conditions for this species.
Continue reading ‘Living under natural conditions of ocean acidification entails energy expenditure and oxidative stress in a mussel species’Time-dependent changes in shrimp armor and escape kinematics under ocean acidification and warming
Published 13 May 2024 Science ClosedTags: biological response, chemistry, crustaceans, morphology, multiple factors, performance, physiology, temperature
Pandalid shrimp use morphological and behavioral defenses against their numerous fish and invertebrate predators. Their rapid tail-flip escape and rigid exoskeleton armor may be sensitive to changes in ocean temperature and carbon chemistry in ways that alter their efficacy and impact mortality. Here we tested the hypothesis that ocean warming and acidification conditions affect the anti-predator defenses of Pandalus gurneyi. To test this hypothesis, we exposed shrimp to a combination of pH (8.0, 7.7, 7.5) and temperature (13°C, 17°C) treatments and assessed their tail-flip escape and exoskeleton armor after short-term (2 weeks) and medium-term (3 months) exposure. Results revealed complex effects on escape kinematics, with changes in different variables explained by either pH, temperature, and/or their interaction; decreased pH, for instance, primarily explains reduced acceleration while cold temperature explains increased flexion duration. Carapace mineral content (Ca and Mg) was unaffected, but warmer temperatures primarily drove enhanced mechanical properties (increased hardness and stiffness). No effects were observed in the stiffness and strength of the rostrum. Furthermore, most of the observed effects were temporary, as they occurred after short-term exposure (2 weeks), but disappeared after longer exposure (3 months). This demonstrates that P. gurneyi defenses are affected by short-term exposure to temperature and pH variations, however, they can acclimate to these conditions over time. Nonetheless, changes in the tail-flip escape kinematics may be disadvantageous when trying to flee predators and the enhanced exoskeleton armor could make them more resistant to predation during short periods of environmental change.
Continue reading ‘Time-dependent changes in shrimp armor and escape kinematics under ocean acidification and warming’Environmental correlates of oyster farming in an upwelling system: implication upon growth, biomass production, shell strength and organic composition
Published 9 May 2024 Science ClosedTags: biological response, chemistry, field, fisheries, mollusks, morphology, performance, physiology, South Pacific
Highlights
- Oysters cultured deeper in upwelling systems are exposed to hypoxia and acidification.
- Reduced growth, size, and condition index are observed in these oysters.
- The oysters also change the shell chemistry and increase its resistance.
- Upwelling intensification could negatively affect oyster aquaculture.
Abstract
Comprehending the potential effects of environmental variability on bivalves aquaculture becomes crucial for its sustainability under climate change scenarios, specially in the Humboldt Current System (HCS) where upwelling intensification leading to frequent hypoxia and acidification is expected. In a year-long study, Pacific oysters (Magallana gigas) were monitored at two depths (1.5m, 6.5m) in a bay affected by coastal upwelling. Surface waters exhibited warmer, well-oxygenated conditions and higher chlorophyll-a concentrations, while at depth greater hypoxia and acidification events occur, especially during upwelling. Surface cultured oysters exhibited 60 % larger size and 35% greater weight due to faster growth rate during the initial month of cultivation. The condition index (CI) increases in surface oysters after 10 months, whereas those at the bottom maintain a lower index. Food availability, temperature, and oxygen, correlates with higher growth rates, while pH associates with morphometric variables, indicating that larger oysters tend to develop under higher pH. Increased upwelling generally raises CI, but bottom oysters face stressful conditions such as hypoxia and acidification, resulting in lower performance. However, they acclimate by changing the organic composition of their shells and making them stronger. This study suggests that under intensified upwelling scenario, oysters would grow slowly, resulting in smaller sizes and lower performance, but the challenges may be confronted through complex compensation mechanisms among biomass production and maintenance of the shell structure and function. This poses a significant challenge for the sustainability of the aquaculture industry, emphasizing the need for adaptive strategies to mitigate the effects of climate change.
Continue reading ‘Environmental correlates of oyster farming in an upwelling system: implication upon growth, biomass production, shell strength and organic composition’Shark critical life stage vulnerability to monthly temperature variations under climate change
Published 8 May 2024 Science ClosedTags: biological response, fish, growth, laboratory, morphology, multiple factors, North Atlantic, performance, physiology, reproduction, respiration, temperature
Highlights
- Summer temperatures revealed embryo vulnerability to seasonal fluctuations.
- Hatching success ranged from 82% in control and SSP2-4.5 to 11% in SSP5-8.5.
- The death of embryos was preceded by distinct individual growth trajectories.
Abstract
In a 10-month experimental study, we assessed the combined impact of warming and acidification on critical life stages of small-spotted catshark (Scyliorhinus canicula). Using recently developed frameworks, we disentangled individual and group responses to two climate scenarios projected for 2100 (SSP2-4.5: Middle of the road and SSP5-8.5: Fossil-fueled Development). Seasonal temperature fluctuations revealed the acute vulnerability of embryos to summer temperatures, with hatching success ranging from 82% for the control and SSP2-4.5 treatments to only 11% for the SSP5-8.5 treatment. The death of embryos was preceded by distinct individual growth trajectories between the treatments, and also revealed inter-individual variations within treatments. Embryos with the lowest hatching success had lower yolk consumption rates, and growth rates associated with a lower energy assimilation, and almost all of them failed to transition to internal gills. Within 6 months after hatching, no additional mortality was observed due to cooler temperatures.
Continue reading ‘Shark critical life stage vulnerability to monthly temperature variations under climate change’The combined effects of ocean warming and ocean acidification on Pacific cod (Gadus macrocephalus) early life stages
Published 2 May 2024 Science ClosedTags: biological response, chemistry, fish, growth, laboratory, morphology, mortality, multiple factors, North Pacific, performance, physiology, reproduction, temperature
The eastern North Pacific is simultaneously experiencing ocean warming (OW) and ocean acidification (OA), which may negatively affect fish early life stages. Pacific cod (Gadus macrocephalus) is an economically and ecologically important species with demonstrated sensitivity to OW and OA, but their combined impacts are unknown. Through a ~ 9-week experiment, Pacific cod embryos and larvae were reared at one of six combinations of three temperatures (3, 6, 10 °C) and two CO2 levels (ambient: ~ 360 μatm; high: ~ 1560 μatm) in a factorial design. Both embryonic and larval mortality were highest at the warmest temperature. Embryonic daily mortality rates were lower under elevated CO2 and there was no effect of CO2 level on larval daily mortality rates. Growth rates of young larvae (0 to 11 days post-hatch) were faster at warmer temperatures and at high CO2 levels, but growth during the 11–28 days post-hatch interval increased by temperature alone. The condition of larvae decreased with age, but less markedly under high CO2 levels. However, at 6 °C, fish incubated in ambient CO2 remained in higher condition than fish in the high CO2 treatment throughout the experiment. Overall, temperature had the greater influence on Pacific cod early life stages across each measurement endpoint, while CO2 effects were more modest and inconsistent. Subtle developmental differences in larval Pacific cod could be magnified later in life and important in the context of recruitment. These results show the complexity of stage- and trait-specific responses to and value of investigating the combined effects of co-occurring climatic stressors.
Continue reading ‘The combined effects of ocean warming and ocean acidification on Pacific cod (Gadus macrocephalus) early life stages’Effects of ocean acidification and summer thermal stress on the physiology and growth of the atlantic surfclam (Spisula solidissima)
Published 29 April 2024 Science ClosedTags: biological response, chemistry, laboratory, mollusks, morphology, performance
This study examines the physiological response of the Atlantic surfclam (Spisula solidissima) to ocean acidification in warm summer temperatures. Working with ambient seawater, this experiment manipulated pH conditions while maintaining natural diel fluctuations and seasonal shifts in temperature. One-year-old surfclams were exposed to one of three pH conditions (ambient (control): 7.8 ± 0.07, medium: 7.51 ± 0.10, or low: 7.20 ± 0.10) in flow-through conditions for six weeks, and feeding and digestive physiology was measured after one day, two weeks, and six weeks. After six weeks of exposure to medium and low pH treatments, growth was not clearly affected, and, contrastingly, feeding and digestive physiology displayed variable responses to pH over time. Seemingly, low pH reduced feeding and absorption rates compared to both the medium treatment and ambient (control) condition; however, this response was clearer after two weeks compared to one day. At six weeks, suppressed physiological rates across both pH treatments and the ambient condition suggest thermal stress from high ambient water temperatures experienced the week prior (24–26 °C) dominated over any changes from low pH. Results from this study provide important information about reduced energy acquisition in surfclams in acidified environments and highlight the need for conducting multistressor experiments that consider the combined effects of temperature and pH stress.
Continue reading ‘Effects of ocean acidification and summer thermal stress on the physiology and growth of the atlantic surfclam (Spisula solidissima)’Interactive effects of chronic ocean acidification and warming on the growth, survival, and physiological responses of adults of the temperate sea urchin Strongylocentrotus intermedius
Published 19 April 2024 Science ClosedTags: biological response, chemistry, echinoderms, growth, laboratory, molecular biology, mortality, multiple factors, North Pacific, performance, physiology, temperature
Highlights
- Ocean acidification and warming (OAW) repressed the survival and growth of Strongylocentrotus intermedius.
- OAW altered the relative expression and activities of key metabolic enzymes of S. intermedius.
- OAW attenuated the ATP production and antioxidant capability of S. intermedius.
- Interactive effects of OAW on S. intermedius were analyzed in detail.
Abstract
To investigate the interactive effects of chronic ocean acidification and warming (OAW) on the growth, survival, and physiological responses of sea urchins, adults of the temperate sea urchin Strongylocentrotus intermedius were incubated separately/jointly in acidic (ΔpHNBS = −0.5 units) and thermal (ΔT = +3.0 °C) seawater for 120 days under lab-controlled conditions based on the projected ocean pH and temperature for 2100 put forward by the Intergovernmental Panel on Climate Change (IPCC). Survival rate (SR), average food consumption rate (FCR), gut index (GuI), specific growth rate (SGR), digestive capability, energy production, and antioxidant capability were subsequently determined. The results showed that 1) the SR, FCR, GuI and SGR decreased sharply under OAW conditions. Significant interactive effects of OAW on SR and SGR were observed at 120 days post-incubation (dpi), and on FCR this occurred at 90 dpi. 2) OAW altered the activities of both digestive and antioxidant enzymes. There were significant interaction effects of OAW on the activities of amylase, trehalase, and superoxide dismutase. 3) The relative gene expression levels and activities of key enzymes involved in glycometabolism pathways (i.e., glycolysis and the tricarboxylic acid cycle) were significantly affected by OAW, resulting in an alteration of the total ATP content in the sea urchins. Interaction effects of OAW were observed in both relative gene expression and the activity of enzymes involved in glycolysis (hexokinase), the transformation of glycolysis end-products (lactate dehydrogenase), the tricarboxylic acid cycle (citrate synthetase), and ATP production (Na+/K+-ATPase). The data from this study will enrich our knowledge concerning the combined effects of global climate change on the survival, growth, and physiological responses of echinoderms.
Continue reading ‘Interactive effects of chronic ocean acidification and warming on the growth, survival, and physiological responses of adults of the temperate sea urchin Strongylocentrotus intermedius’Ocean acidification significantly alters the trace element content of the kelp, Saccharina latissima
Published 17 April 2024 Science ClosedTags: algae, biological response, chemistry, laboratory, North Atlantic, performance, physiology
Highlights
- Exposure of S. latissima to higher concentrations of pCO2 caused a significant increase in the content and subcellular heterogeneity of iodine and arsenic in kelp.
- The iodine-to‑calcium and bromine-to‑calcium ratios of kelp increased significantly under high CO2.
- High CO2 significantly reduced levels of copper and cadmium in kelp tissue.
- The elemental content of seaweeds used as food should be carefully monitored as climate change accelerates this century.
Abstract
Seaweeds are ecosystem engineers that can serve as habitat, sequester carbon, buffer ecosystems against acidification, and, in an aquaculture setting, represent an important food source. One health issue regarding the consumption of seaweeds and specifically, kelp, is the accumulation of some trace elements of concern within tissues. As atmospheric CO2 concentrations rise, and global oceans acidify, the concentrations of elements in seawater and kelp may change. Here, we cultivated the sugar kelp, Saccharina latissima under ambient (~400 μatm) and elevated pCO2 (600–2400 μatm) conditions and examined the accumulation of trace elements using x-ray powder diffraction, sub-micron resolution x-ray imaging, and inductively coupled plasma mass spectrometry. Exposure of S. latissima to higher concentrations of pCO2 and lower pH caused a significant increase (p < 0.05) in the iodine and arsenic content of kelp along with increased subcellular heterogeneity of these two elements as well as bromine. The iodine-to‑calcium and bromine-to‑calcium ratios of kelp also increased significantly under high CO2/low pH (p < 0.05). In contrast, high CO2/low pH significantly reduced levels of copper and cadmium in kelp tissue (p < 0.05) and there were significant inverse correlations between concentrations of pCO2 and concentrations of cadmium and copper in kelp (p < 0.05). Changes in copper and cadmium levels in kelp were counter to expected changes in their free ionic concentrations in seawater, suggesting that the influence of low pH on algal physiology was an important control on the elemental content of kelp. Collectively, these findings reveal the complex effects of ocean acidification on the elemental composition of seaweeds and indicate that the elemental content of seaweeds used as food must be carefully monitored as climate change accelerates this century.
Continue reading ‘Ocean acidification significantly alters the trace element content of the kelp, Saccharina latissima’Expansion and diversity of caspases in Mytilus coruscus contribute to larval metamorphosis and environmental adaptation
Published 9 April 2024 Science ClosedTags: biological response, BRcommunity, molecular biology, mollusks, performance, physiology, reproduction
Background
Apoptosis is involved (directly and indirectly) in several physiological processes including tissue remodeling during the development, the turnover of immune cells, and a defense against harmful stimuli. The disordered apoptotic process participates in the pathogenesis of various diseases, such as neoplasms, and chronic inflammatory or systemic autoimmune diseases, which are associated with its inadequate regulation. Caspases are vital components of the apoptotic pathway that are involved in developmental and immune processes. However, genome-wide identification and functional analysis of caspase have not been conducted in Mytilus coruscus, which is an economically important bivalve.
Results
Here, 47 caspase genes were identified from the genomes of M. coruscus, and the expansion of caspase-2/9 and caspase-3/6/7 genes were observed. Tandem duplication acts as an essential driver of gene expansion. The expanded caspase genes were highly diverse in terms of sequence, domain structure, and spatiotemporal expression profiles, suggesting their functional differentiation. The high expression of the expanded caspase genes at the pediveliger larvae stage and the result of apoptosis location in the velum suggest that the apoptosis mediated by them plays a critical role in the metamorphosis of M. coruscus larvae. In gill, caspase genes respond differently to the challenge of different strains, and most caspase-2/9 and caspase-3/6/7 genes were induced by copper stress, whereas caspase-8/10 genes were suppressed. Additionally, most caspase genes were upregulated in the mantle under ocean acidification which could weaken the biomineralization capacity of the mantle tissue.
Conclusions
These results provide a comprehensive overview of the evolution and function of the caspase family and enhanced the understanding of the biological function of caspases in M. coruscus larval development and response to biotic and abiotic challenges.
Continue reading ‘Expansion and diversity of caspases in Mytilus coruscus contribute to larval metamorphosis and environmental adaptation’Disparate response of decapods to low pH: a meta-analysis of life history, physiology and behavior traits across life stages and environments
Published 5 April 2024 Science ClosedTags: biological response, calcification, crustaceans, growth, mortality, performance, physiology, reproduction, review
Highlights
- Predicted level of ocean acidification is a threat for calcifier marine invertebrates.
- Decapods, thought debatable, are presumably resilient.
- Our meta-analysis revealed few impacts that mainly vary across biological traits.
- Effect sizes little vary depending on the life stages and environments.
Abstract
We employed a meta-analysis to determine if the presumed resilience of decapods to ocean acidification extends to all biological aspects, environments, and life stages. Most response categories appeared unaffected by acidification. However, certain fitness-related traits (growth, survival, and, to some extent, calcification) were impacted. Acid-base balance and stress response scaled positively with reductions in pH, which maintains homeostasis, possibly at the cost of other processes. Juveniles were the only stage impacted by acidification, which is believed to reduce recruitment. We observed few differences in responses to acidification among decapods inhabiting contrasting environments. Our meta-analysis shows decapods as a group slightly to moderately sensitive to low pH, with impacts on some biological aspects rather than on all specific life stages or habitats. Although extreme pH scenarios may not occur in the open ocean, coastal and estuarine areas might experience lower pH levels in the near to medium future, posing potential challenges for decapods.
Continue reading ‘Disparate response of decapods to low pH: a meta-analysis of life history, physiology and behavior traits across life stages and environments’Ocean acidification increases susceptibility to sub-zero air temperatures in ecosystem engineers and limits poleward range shifts
Published 21 March 2024 Science ClosedTags: biological response, BRcommunity, echinoderms, laboratory, Mediterranean, mortality, performance, physiology, reproduction
Ongoing climate change has caused rapidly increasing temperatures and an unprecedented decline in seawater pH, known as ocean acidification. Increasing temperatures are redistributing species toward higher and cooler latitudes that are most affected by ocean acidification. While the persistence of intertidal species in cold environments is related to their capacity to resist sub-zero air temperatures, studies have never considered the interacting impacts of ocean acidification and freeze stress on species survival and distribution. Here, a full-factorial experiment was used to study whether ocean acidification increases mortality in subtidal Mytilus trossulus and subtidal M. galloprovincialis, and intertidal M. trossulus following sub-zero air temperature exposure. We examined physiological processes behind variation in freeze tolerance using 1H NMR metabolomics, analyses of fatty acids, and amino acid composition. We show that low pH conditions (pH = 7.5) significantly decrease freeze tolerance in both intertidal and subtidal populations of Mytilus spp. Under current day pH conditions (pH = 7.9), intertidal M. trossulus was more freeze tolerant than subtidal M. trossulus and subtidal M. galloprovincialis. Conversely, under low pH conditions, subtidal M. trossulus was more freeze tolerant than the other mussel categories. Differences in the concentration of various metabolites (cryoprotectants) or in the composition of amino acids and fatty acids could not explain the decrease in survival. These results suggest that ocean acidification can offset the poleward range expansions facilitated by warming and that reduced freeze tolerance could result in a range contraction if temperatures become lethal at the equatorward edge.
Continue reading ‘Ocean acidification increases susceptibility to sub-zero air temperatures in ecosystem engineers and limits poleward range shifts’Effects of reduced seawater pH and oil contamination on bacterial communities and biochemical markers of estuarine animal hosts
Published 18 March 2024 Science ClosedTags: annelids, biological response, chemistry, community composition, laboratory, molecular biology, mollusks, mortality, North Atlantic, otherprocess, performance, physiology, toxicants
Ecosystem functioning depends on complex interactions between microorganisms, hosts, and the environment. Changes in environmental conditions (e.g., ocean acidification) in combination with anthropogenic pollution have been shown to affect the composition and function of free-living microbial communities, but little is known about the effects these stressors on host-associated communities. This study aims to characterize the response of host-associated bacterial communities of the bottom-dwelling polychaete Hediste diversicolor and the epibenthic gastropod Peringia ulvae to oil contamination and reduced seawater pH. The independent and interactive effects of both stressors were simulated under controlled conditions. The response of host-associated bacterial communities was assessed using the high-throughput sequencing of the 16S rRNA gene and several biochemical markers related to host metabolic pathways, e.g., neurotransmission, anaerobic metabolism, biotransformation, oxidative stress, and energy consumption. In H. diversicolor, reduced seawater pH was associated with a high relative abundance of Cyanobacteria, while in P. ulvae oil contamination was associated with a reduction in the relative abundance of Chitinophagales. In P. ulvae, enrichment with oil hydrocarbon-degrading bacteria suggests a possible role of these organisms in the dispersion of oil hydrocarbon degraders. Furthermore, oil supplementation shifted some specific biochemical markers of gastropods related to oxidative stress and energy consumption, which suggests host stress. In general, the bacterial communities and biochemical markers of the gastropod were more affected by stressors than those of the polychaete. Overall, this study contributes to a better understanding of the response of host-associated bacterial communities of benthic macrofauna to anthropogenic contamination and environmental change.
Continue reading ‘Effects of reduced seawater pH and oil contamination on bacterial communities and biochemical markers of estuarine animal hosts’Ocean acidification impact on the uptake of trace elements by mussels and their biochemical effects
Published 13 March 2024 Science ClosedTags: biological response, chemistry, laboratory, metals, mollusks, morphology, multiple factors, North Atlantic, performance, physiology
Highlights
- Copper and cerium bioavailability may increase under ocean acidification.
- Ocean acidification impacts metal accumulation in mussel gills.
- Biochemical responses in M. galloprovincialis altered by trace metals and OA.
- Complex interplay of oxidative stress markers affected by OA and metals.
Abstract
This study delves into the intricate interplay between ocean acidification (OA), metal bioaccumulation, and cellular responses using mussels (Mytilus galloprovincialis) as bioindicators. For this purpose, environmentally realistic concentrations of isotopically labelled metals (Cd, Cu, Ag, Ce) were added to investigate whether the OA increase would modify metal bioaccumulation and induce adverse effects at the cellular level. The study reveals that while certain elements like Cd and Ag might remain unaffected by OA, the bioavailability of Cu and Ce could potentially escalate, leading to amplified accumulation in marine organisms. The present findings highlight a significant rise in Ce concentrations within different mussel organs under elevated pCO2 conditions, accompanied by an increased isotopic fractionation of Ce (140/142Ce), suggesting a heightened potential for metal accumulation under OA. The results suggested that OA influenced metal accumulation in the gills of mussels. Conversely, metal accumulation in the digestive gland was unaffected by OA. The exposure to both trace metals and OA affects the biochemical responses of M. galloprovincialis, leading to increased metabolic capacity, changes in energy reserves, and alterations in oxidative stress markers, but the specific effects on other biomarkers (e.g., lipid peroxidation, some enzymatic responses or acetylcholinesterase activity) were not uniform, suggesting complex interactions between the stressors and the biochemical pathways in the mussels.
Continue reading ‘Ocean acidification impact on the uptake of trace elements by mussels and their biochemical effects’Quantifying the impacts of multiple stressors on the production of marine benthic resources
Published 11 March 2024 Science ClosedTags: abundance, algae, biogeochemistry, biological response, BRcommunity, chemistry, communityMF, laboratory, mesocosms, methods, modeling, mollusks, morphology, mortality, multiple factors, North Atlantic, nutrients, otherprocess, performance, physiology, regionalmodeling, temperature
Coastal ecosystems are among the most heavily affected by climate change and anthropogenic activities, which impacts their diversity, productivity and functioning and puts many of the key ecosystem services that they provide at risk. Although empirical studies have moved beyond single-stressor-single-species experiments with limited extrapolation potential and have increasingly investigated the cumulative effects of simultaneously occurring multiple stressors, consistent generalities have not yet been identified. Upscaling from controlled experiments to natural ecosystems, therefore, remains an unsolved challenge. Disentangling the independent and cumulative effects of multiple stressors across different levels of biological complexity, revealing the underlying mechanisms and understanding how coastal ecosystems may respond to predicted scenarios of global change is critical to manage and protect our natural capital.
In this thesis, I advance multiple stressor research by applying complementary approaches to quantify the impact of multiple stressors on marine benthic resources and thereby help predict the consequences of expected climate change for coastal habitats. First, I present the newly developed experimental platform QIMS (Quantifying the Impacts of Multiple Stressors) that overcomes some of the shortfalls of previous multiple stressor research (Chapter 2). Second, in a novel empirical study, I investigate the independent and combined effects of moderate ocean warming and acidification on the functioning and production of mussels and algae, considering the effects of interspecific interactions in the presence or absence of the respective other species (Chapter 3). Third, I synthesise monitoring data from Dublin Bay (representative of a typical metropolitan estuary) using conditional interference and a Bayesian Network model and provide alternative system trajectories according to different climate change scenarios. From this new model, I deepen the understanding of the complex linkages between environmental conditions and the diversity and functioning of Dublin Bay to support local decision making and management (Chapter 4).
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Continue reading ‘Quantifying the impacts of multiple stressors on the production of marine benthic resources’Ocean acidification and food availability impacts on the metabolism and grazing in a cosmopolitan herbivorous protist Oxyrrhis marina
Published 8 March 2024 Science ClosedTags: abundance, biological response, growth, laboratory, multiple factors, North Pacific, nutrients, otherprocess, performance, physiology, primary production, protists, respiration, zooplankton
The heterotrophic dinoflagellate Oxyrrhis marina is an essential microzooplankton in coastal waters, linking the energy transfer from phytoplankton to higher trophic levels. It is of general significance to investigate how it responds and acclimates to ocean acidification (OA), especially under varied availabilities of food. Here, O. marina was exposed and acclimated to three pCO2 levels (LC: 415, MC:1000, HC:1500 μatm) for 60 days, and then was further grown under the CO2 levels with different levels of food (the microalgae Dunaliella salina) availability for about 8 generations. The OA treatments did not significantly hamper its growth and ingestion rates even under the reduced food availability and starvation (deprived of the microalgae), which significantly reduced its growth rate. While the impacts of OA on the growth and ingestion rates of O. marina were insignificant, the OA treatments appeared to have resulted in a faster decline of the heterotrophic dinoflagellate cells during the starvation period. Nevertheless, the acidic stress under the elevated pCO2 of 1000 or 1500 μatm decreased its respiration by about 53% or 59% with the high and by about 26% or 23% with the low food availability, respectively. Such OA-repressed respiration was also significant during the starvation period. On the other hand, the OA treatments and deprivation of the microalgae synergistically reduced the cellular quota of particulate organic C, N and P, resulting in a reduction of food value of the heterotrophic dinoflagellate as prey. In conclusion, our results show that O. marina is highly resilient to future ocean acidification by reducing its respiration and sustaining its ingestion of microalgae.
Continue reading ‘Ocean acidification and food availability impacts on the metabolism and grazing in a cosmopolitan herbivorous protist Oxyrrhis marina’Critical swimming speed of juvenile rockfishes (Sebastes) following long- and short-term exposures to acidification and deoxygenation
Published 6 March 2024 Science ClosedTags: biological response, fish, laboratory, multiple factors, North Pacific, oxygen, performance
Highlights
- Swimming ability of juvenile rockfishes declined during acute and chronic exposure to deoxygenation and acidification.
- Critical swimming speed of juvenile rockfish was more sensitive to deoxygenation than to acidification.
- The effects of acidified and deoxygenated conditions on juvenile rockfish swimming ability manifest rapidly (hours to days).
- Swimming performance of juvenile rockfish recovered after upwelling-event acidified/deoxygenated conditions had subsided.
- Despite early life history differences, black and copper rockfish had similar sensitivity to acidification and deoxygenation.
Abstract
Reef fishes in the California Current Ecosystem have evolved in habitats affected by seasonally variable, episodic upwelling of high pCO2 (acidified, low pH) and low dissolved oxygen (deoxygenated) water, which suggests that these fishes might exhibit resilience to ocean acidification (OA) and deoxygenation. Yet, how the fitness of these fish are affected by natural variability in pH and DO over short time scales remains poorly understood, as do the effects of longer-term trends in pH and DO driven by climate change. We conducted a complementary suite of experiments to study the effects of acidification and deoxygenation on the critical swimming speed (Ucrit) of juvenile copper (Sebastes caurinus) and black (S. melanops) rockfish collected from nearshore habitats in an ocean acidification “hotspot” off Northern California. We consistently observed that Ucrit declined more strongly in response to deoxygenation than to acidification, at least under ranges of these stressors consistent with current conditions and plausible future scenarios, and that reduction in swimming performance reflected additive rather than synergistic responses to concurrent exposure. Reductions in swimming performance manifested quickly–on the scale of hours–in response to exposure to elevated pCO2/reduced DO, yet are reversible: swimming performance of juvenile rockfish recovers within a matter of days, and perhaps much more quickly, after acidified/deoxygenated conditions have subsided. Insights from this study address potential effects of variability in upwelling intensity at event and seasonal scales for nearshore rockfishes and contribute to our understanding of fish responses to future ocean conditions driven by ongoing climate change.
Continue reading ‘Critical swimming speed of juvenile rockfishes (Sebastes) following long- and short-term exposures to acidification and deoxygenation’
