pH or pCO2 are usually taken to study the impact of ocean acidification on molluscs. Here we studied the different impact of seawater carbonate parameters on embryonic development and calcification of the Pacific abalone (Haliotis discus hannai). Early embryonic development was susceptible to elevated pCO2 level. Larvae hatching duration was positively and hatching rate was negatively correlated with the pCO2 level, respectively. Calcium carbonate (CaCO3) deposition of larval shell was found to be susceptible to calcium carbonate saturation state (Ω) rather than pCO2 or pH. Most larvae incubated in seawater with Ωarag = 1.5 succeeded in shell formation, even when seawater pCO2 level was higher than 3700 μatm and pHT was close to 7.4. Nevertheless, larvae failed to generate CaCO3 in seawater with Ωarag ≤ 0.52 and control level of pCO2, while seawater DIC level was lowered (≤ 852 μmol/kg). Surprisingly, some larvae completed CaCO3 deposition in seawater with Ωarag = 0.6 and slightly elevated DIC (2266 μmol/kg), while seawater pCO2 level was higher than 2700 μatm and pHT was lower than 7.3. This indicates that abalone may be capable of regulating carbonate chemistry to support shell formation, however, the capability was limited as surging pCO2 level lowered growth rate and jeopardized the integrity of larval shells. Larvae generated thicker shell in seawater with Ωarag = 5.6, while adult abalone could not deposit CaCO3 in seawater with Ωarag = 0.29 and DIC = 321 μmol/kg. This indicates that abalone may lack the ability to directly remove or add inorganic carbon at the calcifying sites. In conclusion, different seawater carbonate parameters play different roles in affecting early embryonic development and shell formation of the Pacific abalone, which may exhibit limited capacity to regulate carbonate chemistry.
Continue reading ‘Seawater carbonate parameters function differently in affecting embryonic development and calcification in Pacific abalone (Haliotis discus hannai)’Posts Tagged 'reproduction'
Seawater carbonate parameters function differently in affecting embryonic development and calcification in Pacific abalone (Haliotis discus hannai)
Published 14 March 2023 Science ClosedTags: biological response, laboratory, mollusks, morphology, reproduction
The multi-generational effect of seawater acidification on larval development, reproduction, ingestion rate, and ATPase activity of Tigriopus japonicus Mori, 1938
Published 13 March 2023 Science ClosedTags: biological response, crustaceans, North Pacific, performance, physiology, reproduction, zooplankton
Ocean acidification threatens marine organisms continuously. To ascertain if adaptation of marine species to ocean acidification enhanced over multiple generations, we studied the transgenerational effects of ocean acidification on the development, reproduction, ingestion rate, and ATPase activity of a copepod Tigriopus japonicus Mori, 1938. In the first mode, individuals were exposed to either one of the pH levels (8.1 (control), 7.7, 7.3) for five successive generations. In the second mode, each successive generation was exposed to a lower pH level (pH levels: 8.1, 7.9, 7.7, 7.5, 7.3). After prolonged exposure to a constant seawater acidification level, the capacity to adapt to the stress increased. However, when exposed to seawater of descending pH, the detrimental effects gradually increased. Energy allocated to development and reproduction was reduced although the ingestion rate continued to improve in successive generations. Therefore, ongoing ocean acidification might lower the energy transfer of copepods to higher trophic levels.
Continue reading ‘The multi-generational effect of seawater acidification on larval development, reproduction, ingestion rate, and ATPase activity of Tigriopus japonicus Mori, 1938’Effects of elevated CO2 on metabolic rate and nitrogenous waste handling in the early life stages of yellowfin tuna (Thunnus albacares)
Published 6 March 2023 Science ClosedTags: biological response, fish, laboratory, physiology, reproduction
Highlights
- Little is known about how tuna species will respond to ocean acidification (OA).
- CO2 altered nitrogenous waste excretion and metabolic rate in yolk sac larvae.
- CO2 did not change yolk sac depletion in embryos.
- CO2 did not alter nitrogen accumulation in yellowfin tuna.
- Yellowfin tuna were more robust to CO2 than predicted.
Abstract
Ocean acidification is predicted to have a wide range of impacts on fish, but there has been little focus on broad-ranging pelagic fish species. Early life stages of fish are thought to be particularly susceptible to CO2 exposure, since acid-base regulatory faculties may not be fully developed. We obtained yellowfin tuna (Thunnus albacares) from a captive spawning broodstock population and exposed them to control or 1900 μatm CO2 through the first three days of development as embryos transitioned into yolk sac larvae. Metabolic rate, yolk sac depletion, and oil globule depletion were measured to assess overall energy usage. To determine if CO2 altered protein catabolism, tissue nitrogen content and nitrogenous waste excretion were quantified. CO2 exposure did not significantly impact embryonic metabolic rate, yolk sac depletion, or oil globule depletion, however, there was a significant decrease in metabolic rate at the latest measured yolk sac larval stage (36 h post fertilization). CO2-exposure led to a significant increase in nitrogenous waste excretion in larvae, but there were no differences in nitrogen tissue accumulation. Nitrogenous waste accumulated in embryos as they developed but decreased after hatch, coinciding with a large increase in nitrogenous waste excretion and increased metabolic rate in newly hatched larvae. Our results provide insight into how yellowfin tuna are impacted by increases in CO2 in early development, but more research with higher levels of replication is needed to better understand long-term impacts and acid-base regulatory mechanisms in this important pelagic fish.
Continue reading ‘Effects of elevated CO2 on metabolic rate and nitrogenous waste handling in the early life stages of yellowfin tuna (Thunnus albacares)’Thanks mum. Maternal effects in response to ocean acidification of sea urchin larvae at different ecologically relevant temperatures
Published 3 March 2023 Science ClosedTags: biological response, echinoderms, Mediterranean, morphology, multiple factors, reproduction, temperature, vents
Highlights
- Ocean acidification and temperature differently influence larval development of Arbacia lixula and Paracentrotus lividus.
- Larvae of the two A. lixula populations (ambient-pH vs vent sites) respond differently to ocean acidification and temperature.
- Maternal buffer effect was observed in response to ocean acidification and temperature in both species.
- A. lixula seems to be more tolerant to changes in temperature than P. lividus.
Abstract
Juvenile stages of marine species might be more vulnerable than adults to climate change, however larval vulnerability to predictable environmental changes can be mitigated by parental anticipatory buffer effects occurring during gametogenesis. In this study, ocean acidification effect were investigated on larval growth of two sea urchins, Arbacia lixula and Paracentrotus lividus, at different temperature levels. Results showed that altered pH and temperature affected larval development in both species, with significant length reductions of spicules and significant increases in abnormal larvae. Detrimental effects of reduced pH and high temperature were however dependent on the mother. Furthermore, the responses of A. lixula larvae from the ambient site (pH ∼ 8.0) were compared with those of larvae obtained from mothers collected from a natural CO2 vent (pH ∼ 7.7) in Ischia. Comparisons highlighted a transgenerational response, as the CO2 vent larvae proved to be more resilient to reduced pH, although more sensitive to increased temperature.
Continue reading ‘Thanks mum. Maternal effects in response to ocean acidification of sea urchin larvae at different ecologically relevant temperatures’The effect of pH on the larvae of two sea urchin species using different pH manipulation methods
Published 27 February 2023 Science ClosedTags: biological response, echinoderms, laboratory, methods, morphology, mortality, reproduction
Climate change alters ocean pH, temperature, and salinity, which presents challenges for oceanic organisms, especially those with calcium carbonate skeletons. Our research examines how decreasing pH impacts larval survivorship and calcium carbonate skeletal development of two sea urchin species, Lytechinus variegatus and Arbacia punctulata. Based on previous work in various sea urchin species, it is expected that as pH decreases, survivorship decreases and skeletal malformations increase. Both L. variegatus and A. punctulata have been used in prior studies to explore pH change on survivorship and development, but these studies incorporated various outcomes and pH manipulation methods, limiting how comparable they are. Therefore, we wanted to measure the same outcomes between species and compare the effect of different pH manipulation within species. We altered pH by either HCL addition or CO2 bubbling through seawater. Larvae, at a concentration of 3 larvae/ml, were exposed to seawater of pH 8.4, 8.0, or 7.6. For each treatment, survivorship of 30-40 larvae was measured daily for 10-14 days depending on the trial. Larval malformations were quantified for about 10 larvae from daily fixed samples. Larval arm length, body length, and body width were measured using Image J. For both methods of pH manipulation and both species, there was a statistically significant (p<0.001) decrease in survivorship as pH decreases consistent with the prediction. Preliminary analysis of skeletal deformities suggests malformations increase as pH decreases, but data are still being collected. Similar abnormalities observed between species regardless of pH manipulations include uneven or missing arms and misshapen aboral sides. The effect of pH on larval survivorship and development in L. variegatus and A. punctulata are comparable to observations in other species suggesting effects are consistent across manipulation methods and species. With this research, we can continue to fine-tune methodology and build on our understanding of how climate change-driven ocean acidification can impact species.
Continue reading ‘The effect of pH on the larvae of two sea urchin species using different pH manipulation methods’Parental exposure to ocean acidification impacts gamete production and physiology but not offspring performance in Nematostella vectensis
Published 21 February 2023 Science ClosedTags: biological response, cnidaria, molecular biology, performance, physiology, reproduction
Ocean acidification (OA) resulting from anthropogenic CO2 emissions is impairing the reproduction of marine organisms. While parental exposure to OA can protect offspring via carryover effects, this phenomenon is poorly understood in many marine invertebrate taxa. Here, we examined how parental exposure to acidified (pH 7.40) versus ambient (pH 7.72) seawater influenced reproduction and offspring performance across six gametogenic cycles (13 weeks) in the estuarine sea anemone Nematostella vectensis. Females exhibited reproductive plasticity under acidic conditions, releasing significantly fewer but larger eggs compared to ambient females after four weeks of exposure, and larger eggs in two of the four following spawning cycles despite recovering fecundity, indicating long-term acclimatization and greater investment in eggs. Males showed no changes in fecundity under acidic conditions, but produced a greater percentage of sperm with high mitochondrial membrane potential (MMP; a proxy for elevated motility), which corresponded with higher fertilization rates relative to ambient males. Finally, parental exposure to acidic conditions did not significantly influence offspring development rates, respiration rates, or heat tolerance. Overall, this study demonstrates that parental exposure to acidic conditions impacts gamete production and physiology but not offspring performance in N. vectensis, suggesting that increased investment in individual gametes may promote fitness.
Continue reading ‘Parental exposure to ocean acidification impacts gamete production and physiology but not offspring performance in Nematostella vectensis’RNAi silencing of the biomineralization gene perlucin impairs oyster ability to cope with ocean acidification
Published 17 February 2023 Science ClosedTags: biological response, laboratory, molecular biology, mollusks, morphology, physiology, reproduction
Calcifying marine organisms, including the eastern oyster (Crassostrea virginica), are vulnerable to ocean acidification (OA) because it is more difficult to precipitate calcium carbonate (CaCO3). Previous investigations of the molecular mechanisms associated with resilience to OA in C. virginica demonstrated significant differences in single nucleotide polymorphism and gene expression profiles among oysters reared under ambient and OA conditions. Converged evidence generated by both of these approaches highlighted the role of genes related to biomineralization, including perlucins. Here, gene silencing via RNA interference (RNAi) was used to evaluate the protective role of a perlucin gene under OA stress. Larvae were exposed to short dicer-substrate small interfering RNA (DsiRNA-perlucin) to silence the target gene or to one of two control treatments (control DsiRNA or seawater) before cultivation under OA (pH ~7.3) or ambient (pH ~8.2) conditions. Two transfection experiments were performed in parallel, one during fertilization and one during early larval development (6 h post-fertilization), before larval viability, size, development, and shell mineralization were monitored. Silenced oysters under acidification stress were the smallest, had shell abnormalities, and had significantly reduced shell mineralization, thereby suggesting that perlucin significantly helps larvae mitigate the effects of OA.
Continue reading ‘RNAi silencing of the biomineralization gene perlucin impairs oyster ability to cope with ocean acidification’Life-stage-dependent effects of multiple flood-associated stressors on a coastal foundational species
Published 15 February 2023 Science ClosedTags: biological response, growth, laboratory, mollusks, morphology, mortality, multiple factors, oxygen, reproduction, salinity
Global changes in precipitation patterns have increased the frequency and duration of flooding events. Freshwater inflows into estuaries reduce salinity levels and increase nutrient inputs, which can lead to eutrophication and impaired water quality. Oysters are important ecosystem engineers in coastal environments that are vulnerable to co-occurring environmental stressors associated with freshwater flooding events. Successful recruitment is necessary to maintain adult oyster populations, but early life stage responses to multiple stressors are not well understood. Flood-associated stressor conditions were observed near oyster habitats at multiple locations across the northern Gulf of Mexico during peak recruitment months in the spring and summer of 2021. In the laboratory, we examined the interactive effects of acidification, hypoxia, and low salinity on larval and juvenile life stages of the eastern oyster (Crassostrea virginica) to better understand the impact of flooding events on oyster development and survival. Salinity stress in isolation reduced larval growth and settlement, and decreased survival and growth at the juvenile stage. Hypoxia was more stressful to oyster larvae than to juveniles, whereas low pH had negative effects on juvenile growth. There were no synergistic effects of multiple flood-associated stressors on early oyster life stages and effects were either additive or predicted by the salinity stress response. The negative impacts of flooding disturbances on recruitment processes in benthic populations need to be considered in restoration planning and flood control mitigation strategies as the frequency and intensity of extreme freshwater events continue to rise worldwide.
Continue reading ‘Life-stage-dependent effects of multiple flood-associated stressors on a coastal foundational species’Analysis of spawning behaviour and growth indices of zebrafish in response to CO2 acidification
Published 10 February 2023 Science ClosedTags: biological response, fish, laboratory, mortality, reproduction
The growth parameters and spawning behaviour of zebrafish in response to CO2 acidification demonstrated differential results. The growth performance of zebrafish is determined by key indices, BWG, SGR, CF and CV. BWG shows subtle gain in 1500 µatm group (0.09 g) and a slight decrease in 2200 µatm group (0.056 g). SGR index showed similar pattern of results, whereas CF showed a gradual decrease. The other growth index CV again showed an increase in 1500 µatm group and slight decrease in 2200 µatm group in comparison to the control group. A significant decrease in the performance of spawning behaviour was observed. At 96 hpf, the survival rate of the embryos showed a significant hit and the number of dead embryos increased dose dependently. The embryos exposed to CO2 showed a decrease in hatching rate with the increase in dose of CO2. The CO2 acidification causes notable changes in the growth and significant effect on reproductive behaviour.
Continue reading ‘Analysis of spawning behaviour and growth indices of zebrafish in response to CO2 acidification’Potential ecosystem regime shift resulting from elevated CO2 and inhibition of macroalgal recruitment by turf algae
Published 31 January 2023 Science ClosedTags: algae, biological response, individualmodeling, modeling, reproduction
Rising carbon dioxide (CO2) concentrations are predicted to cause an undesirable transition from macroalgae-dominant to turf algae-dominant ecosystems due to its effect on community structuring processes. As turf algae are more likely to proliferate due to the CO2 fertilization effect than macroalgae and often inhibit macroalgal recruitment, increased CO2 beyond certain levels may produce novel positive feedback loops that promote turf algae growth and thus can stabilize turf algae-dominant ecosystems. In this study, we built a simple competition model between macroalgae and turf algae in a homogeneous space to investigate the steady-state response of the ecosystem to changes in the partial pressure of CO2 (pCO2). We found that discontinuous regime shifts in response to pCO2 change can occur once turf algae coverage reaches a critical level capable of inhibiting macroalgal recruitment. The effect of localized turf algae density on the success rate of macroalgae recruitment was also investigated using a patch model that simulated a two-dimensional heterogeneous space. This suggested that in addition to the inhibitory effect by turf algae, a self-enhancing effect by macroalgae could also be important in predicting the potential discontinuous regime shifts in response to future pCO2 changes.
Continue reading ‘Potential ecosystem regime shift resulting from elevated CO2 and inhibition of macroalgal recruitment by turf algae’Response mechanism of harmful algae Phaeocystis globosa to ocean warming and acidification
Published 30 January 2023 Science ClosedTags: adaptation, algae, biological response, laboratory, molecular biology, North Pacific, otherprocess, physiology, reproduction
Simultaneous ocean warming and acidification will alter marine ecosystem structure and directly affect marine organisms. The alga Phaeocystis globosa commonly causes harmful algal blooms in coastal areas of eastern China. P. globosa often outcompetes other species due to its heterotypic life cycle, primarily including colonies and various types of solitary cells. However, little is known about the adaptive response of P. globosa to ocean warming and acidification. This study aimed to reveal the global molecular regulatory networks implicated in the response of P. globosa to simultaneous warming and acidification. After exposure to warming and acidification, the phosphatidylinositol (PI) and mitogen-activated protein kinase (MAPK) signaling pathways of P. globosa were activated to regulate other molecular pathways in the cell, while the light harvesting complex (LHC) genes were downregulated to decrease photosynthesis. Exposure to warming and acidification also altered the intracellular energy flow, with more energy allocated to the TCA cycle rather than to the biosynthesis of fatty acids and hemolytic substances. The upregulation of genes associated with glycosaminoglycan (GAG) degradation prevented the accumulation of polysaccharides, which led to a reduction in colony formation. Finally, the upregulation of the Mre11 and Rad50 genes in response to warming and acidification implied an increase in meiosis, which may be used by P. globosa to increase the number of solitary cells. The increase in genetic diversity through sexual reproduction may be a strategy of P. globosa that supports rapid response to complex environments. Thus, the life cycle of P. globosa underwent a transition from colonies to solitary cells in response to warming and acidification, suggesting that this species may be able to rapidly adapt to future climate changes through life cycle transitions.
Continue reading ‘Response mechanism of harmful algae Phaeocystis globosa to ocean warming and acidification’Effect of pH on the early development of the biofouling ascidian Ciona robusta
Published 26 January 2023 Science ClosedTags: biological response, chordata, laboratory, morphology, mortality, reproduction
Ocean acidification (OA) impacts the survival, fertilization, and community structure of marine organisms across the world. However, some populations or species are considered more resilient than others, such as those that are invasive, globally distributed, or biofouling. Here, we tested this assumption by investigating the effect of pH on the larval development of one such tunicate, Ciona robusta, which is currently exposed to a wide range of pH levels. Consistent with our hypothesis, C. robusta larvae developed and metamorphosed at a rate comparable to control (pH 8.0) at modest near-future conditions (pH 7.7) over a 58-hour period. However, development was stunted at the extreme low pH of 6.8 such that no embryo progressed beyond late cleavage after 58 hours. Interestingly, piecewise regression of the proportion of embryos at the most advanced stage at a given time point against pH identified a breakpoint with the highest pH (~pH 7.6) at around hatching. The variation in breakpoint pH throughout ontogeny highlighted that the sensitivity to decreasing pH differs significantly between developmental stages. More broadly, our results show that even a cosmopolitan, biofouling, invasive species could be negatively impacted by decreasing pH.
Continue reading ‘Effect of pH on the early development of the biofouling ascidian Ciona robusta’Charge-dependent negative effects of polystyrene nanoplastics on Oryzias melastigma under ocean acidification conditions
Published 24 January 2023 Science ClosedTags: biological response, fish, laboratory, light, morphology, mortality, multiple factors, performance, reproduction, toxicants
Highlights
- PS-NH2 exhibited more aggregation than PS-COOH in acidified seawater.
- Ocean acidification reversed toxicity of positively and negatively charged NPs.
- Ocean acidification reversed the internalization of PS-NH2 and PS-COOH.
- PS-NPs at environmental level could transfer from embryos to larvae.
Abstract
Marine nanoplastics (NPs) have attracted increasing global attentions because of their detrimental effects on marine environments. A co-existing major environmental concern is ocean acidification (OA). However, the effects of differentially charged NPs on marine organisms under OA conditions are poorly understood. We therefore investigated the effects of OA on the embryotoxicity of both positively and negatively charged polystyrene (PS) NPs to marine medaka (Oryzias melastigma). Positively charged PS-NH2 exhibited slighter aggregation under normal conditions and more aggregation under OA conditions than negatively charged PS-COOH. According to the integrated biomarker approach, OA reversed the toxicity of positively and negatively charged NPs towards embryos. Importantly, at environmental relevant concentrations, both types of PS-NPs could enter the embryos through chorionic pores and then transfer to the larvae. OA reversed the internalization of PS-NH2 and PS-COOH in O. melastigma. Overall, the reversed toxicity of PS-NH2 and PS-COOH associated with OA could be caused by the reversed bioavailability of NPs to O. melastigma, which was attributed to altered aggregation of the NPs in acidified seawater. This finding demonstrates the charge-dependent toxicity of NPs to marine fish and provides new insights into the potential hazard of NPs to marine environments under OA conditions that could be encountered in the near future.
Continue reading ‘Charge-dependent negative effects of polystyrene nanoplastics on Oryzias melastigma under ocean acidification conditions’Ocean acidification increases the impact of typhoons on algal communities
Published 24 January 2023 Science ClosedTags: algae, biological response, chemistry, community composition, field, North Pacific, physiology, reproduction
Highlights
- Algal community dynamics studied with three-year monthly surveys at a CO2 seep
- Acidification consistently altered community composition across all seasons
- Structurally complex communities shifted to degraded ‘turf’ state with rising pCO2
- Acidification-driven community changes were maintained by typhoon disturbance
- Turf-dominated communities displayed low resistance to typhoons
Abstract
Long-term environmental change, sudden pulses of extreme perturbation, or a combination of both can trigger regime shifts by changing the processes and feedbacks which determine community assembly, structure, and function, altering the state of ecosystems. Our understanding of the mechanisms that stabilise against regime shifts or lock communities into altered states is limited, yet also critical to anticipating future states, preventing regime shifts, and reversing unwanted state change. Ocean acidification contributes to the restructuring and simplification of algal systems, however the mechanisms through which this occurs and whether additional drivers are involved requires further study. Using monthly surveys over three years at a shallow-water volcanic seep we examined how the composition of algal communities change seasonally and following periods of significant physical disturbance by typhoons at three levels of ocean acidification (equivalent to means of contemporary ∼350 and future ∼500 and 900 μatm pCO2). Sites exposed to acidification were increasingly monopolised by structurally simple, fast-growing turf algae, and were clearly different to structurally complex macrophyte-dominated reference sites. The distinct contemporary and acidified community states were stabilised and maintained at their respective sites by different mechanisms following seasonal typhoon disturbance. Macroalgal-dominated sites were resistant to typhoon damage. In contrast, significant losses of algal biomass represented a near total ecosystem reset by typhoons for the turf-dominated communities at the elevated pCO2 sites (i.e. negligible resistance). A combination of disturbance and subsequent turf recovery maintained the same simplified state between years (elevated CO2 levels promote turf growth following algal removal, inhibiting macroalgal recruitment). Thus, ocean acidification may promote shifts in algal systems towards degraded ecosystem states, and short-term disturbances which reset successional trajectories may ‘lock-in’ these alternative states of low structural and functional diversity.
Continue reading ‘Ocean acidification increases the impact of typhoons on algal communities’Transgenerational transfer of the microbiome is altered by ocean acidification in oyster larvae
Published 10 January 2023 Science ClosedTags: biological response, BRcommunity, laboratory, molecular biology, mollusks, physiology, protists, reproduction
Ocean acidification will affect marine molluscs, however, transgenerational plasticity (TGP) can ameliorate some effects. Marine molluscs acquire members of their microbiome via the egg, yet we know little about how the microbiome can be influenced by transgenerational exposure to ocean acidification. We exposed adult Sydney Rock oysters (Saccostrea glomerata) from four genotypes to elevated and ambient PCO2 for nine weeks. Larvae were then raised in the same ambient and elevated PCO2 conditions. The relative abundance of bacteria in eggs and larvae were characterised using 16S RNA amplicon sequencing. Parental exposure to elevated PCO2 significantly altered the bacterial community composition of both eggs and larvae, but this was dependent on genotype. Parental exposure to elevated PCO2 caused five core Rhodobacteraceae ASVs to increase in relative abundance, and three Rhodobacteraceae ASVs to decrease in relative abundance. These findings show transfer of maternal microbiomes to larvae is altered by exposure to ocean acidification and this may play a role in TGP.
Continue reading ‘Transgenerational transfer of the microbiome is altered by ocean acidification in oyster larvae’Multistressor global change drivers reduce hatch and viability of Lingcod embryos, a benthic egg layer in the California Current System
Published 10 January 2023 Science ClosedTags: biological response, fish, laboratory, morphology, mortality, multiple factors, North Pacific, oxygen, physiology, reproduction, temperature
Early life history stages of marine fishes are often more susceptible to environmental stressors than adult stages. This vulnerability is likely exacerbated for species that lay benthic egg masses bound to substrate because the embryos cannot evade locally unfavorable environmental conditions. Lingcod (Ophiodon elongatus), a benthic egg layer, is an ecologically and economically significant predator in the highly-productive California Current System (CCS). We ran a flow-through mesocosm experiment that exposed Lingcod eggs collected from Monterey Bay, CA to conditions we expect to see in the central CCS by the year 2050 and 2100. Exposure to temperature, pH, and dissolved oxygen concentrations projected by the year 2050 halved the successful hatch of Lingcod embryos and significantly reduced the size of day-1 larvae. In the year 2100 treatment, viable hatch plummeted (3% of normal), larvae were undersized (83% of normal), yolk reserves were exhausted (38% of normal), and deformities were widespread (94% of individuals). This experiment is the first to expose marine benthic eggs to future temperature, pH, and dissolved oxygen conditions in concert. Lingcod are a potential indicator species for other benthic egg layers for which global change conditions may significantly diminish recruitment rates.
Continue reading ‘Multistressor global change drivers reduce hatch and viability of Lingcod embryos, a benthic egg layer in the California Current System’Impacts of ocean acidification and warming on post-larval growth and metabolism in two populations of the great scallop (Pecten maximus L.)
Published 29 December 2022 Science ClosedTags: biological response, field, molecular biology, mollusks, morphology, mortality, multiple factors, North Atlantic, physiology, reproduction, temperature
Ocean acidification and warming are key stressors for many marine organisms. Some organisms display physiological acclimatisation or plasticity, but this may vary across species ranges, especially if populations are adapted to local climatic conditions. Understanding how acclimatisation potential varies among populations is therefore important in predicting species responses to climate change. We carried out a common garden experiment to investigate how different populations of the economically important great scallop (Pecten maximus) from France and Norway responded to variation in temperature and pCO2 concentration. After acclimation, post-larval scallops (spat) were reared for 31 days at one of two temperatures (13°C and 19°C) under either ambient or elevated pCO2 (pH 8.0 and pH 7.7). We combined measures of proteomic, metabolic, and phenotypic traits to produce an integrative picture of how physiological plasticity varies between the populations. The proteome of French spat showed significant sensitivity to environmental variation, with 12 metabolic, structural and stress-response proteins responding to temperature and/or pCO2. Principal component analysis revealed seven energy metabolism proteins in French spat that were consistent with countering ROS stress under elevated temperature. Oxygen uptake in French spat did not change under elevated temperature, but increased under elevated pCO2. In contrast, Norwegian spat reduced oxygen uptake under both elevated temperature and pCO2. Metabolic plasticity seemingly allowed French scallops to maintain greater energy availability for growth than Norwegian spat. However, increased physiological plasticity and growth in French spat may come at a cost, as French (but not Norwegian) spat showed reduced survival under elevated temperature.
Continue reading ‘Impacts of ocean acidification and warming on post-larval growth and metabolism in two populations of the great scallop (Pecten maximus L.)’A positive temperature-dependent effect of elevated CO2 on growth and lipid accumulation in the planktonic copepod, Calanus finmarchicus
Published 23 December 2022 Science ClosedTags: biological response, crustaceans, laboratory, morphology, multiple factors, North Atlantic, physiology, reproduction, temperature, zooplankton
Calanus finmarchicus were reared from eggs to adults at 12°C and 16°C with non-limiting food in combination with ambient (600 μatm) and high (1100 μatm) pCO2. These conditions are likely to be encountered by the species at the southern margins of its biogeographical range by the end of the century. Dry weight (DW), carbon (C) and nitrogen (N) mass, oil-sac volume (OSV), fatty acid composition (FA), and oxygen consumption rates (OCR) were measured on newly molted stage CV copepodites and recently molted adult females. By focusing our measurements on these precise events in the life cycle, we were able to obtain a more accurate comparison of growth and respiration across treatments. Copepods raised at 12°C had a significantly greater DW, OSV, and C and N mass than those raised at 16°C High pCO2, independent of temperature, was associated with a further increase in the DW and C content of the copepods. Interactive effects of temperature and pCO2 resulted in a larger OSV at low temperature and high pCO2. Mass-specific respiration rates were significantly lower at lower temperatures and elevated pCO2 suggesting that the increase in mass (DW, C, and OSV) resulted from reduced metabolic cost. The composition of fatty acids in the copepods varied mainly with temperature. Two fatty acids varied with pCO2: 16:0 tended to decrease with higher pCO2 and 18:3n−3 tended to increase with higher pCO2. These observations suggest that elevated pCO2/lower pH in future oceans may have a beneficial effect on C. finmarchicus.
Continue reading ‘A positive temperature-dependent effect of elevated CO2 on growth and lipid accumulation in the planktonic copepod, Calanus finmarchicus’The effects of temperature and pH on the reproductive ecology of sand dollars and sea urchins: impacts on sperm swimming and fertilization
Published 22 December 2022 Science ClosedTags: biological response, echinoderms, laboratory, multiple factors, North Pacific, reproduction, temperature
In an era of climate change, impacts on the marine environment include warming and ocean acidification. These effects can be amplified in shallow coastal regions where conditions often fluctuate widely. This type of environmental variation is potentially important for many nearshore species that are broadcast spawners, releasing eggs and sperm into the water column for fertilization. We conducted two experiments to investigate: 1) the impact of water temperature on sperm swimming characteristics and fertilization rate in sand dollars (Dendraster excentricus; temperatures 8-38°C) and sea urchins (Mesocentrotus franciscanus; temperatures 8-28°C) and; 2) the combined effects of multiple stressors (water temperature and pH) on these traits in sand dollars. We quantify thermal performance curves showing that sand dollar fertilization rates, sperm swimming velocities, and sperm motility display remarkably wide thermal breadths relative to red urchins, perhaps reflecting the wider range of water temperatures experienced by sand dollars at our field sites. For sand dollars, both temperature (8, 16, 24°C) and pH (7.1, 7.5, 7.9) affected fertilization but only temperature influenced sperm swimming velocity and motility. Although sperm velocities and fertilization were positively correlated, our fertilization kinetics model dramatically overestimated measured rates and this discrepancy was most pronounced under extreme temperature and pH conditions. Our results suggest that environmental stressors like temperature and pH likely impair aspects of the reproductive process beyond simple sperm swimming behavior.
Continue reading ‘The effects of temperature and pH on the reproductive ecology of sand dollars and sea urchins: impacts on sperm swimming and fertilization’
