Planktonic Foraminifera are ubiquitous marine protozoa inhabiting the upper ocean. During life, they secrete calcareous shells, which accumulate in marine sediments, providing a geological record of past spatial and temporal changes in their community structure. As a result, they provide the opportunity to analyze both current and historical patterns of species distribution and community turnover in this plankton group on a global scale. The FORCIS project aims to unlock this potential by synthesizing a comprehensive global database of abundance and diversity observations of living planktonic Foraminifera in the upper ocean over more than 100 years starting from 1910. The database will allow for unravelling the impact of multiple global-change stressors acting on planktonic Foraminifera in historical times, using an approach that combines statistical analysis of temporal diversity changes in response to environmental changes with numerical modeling of species response based on their ecological traits.
Continue reading ‘The Foraminiferal response to climate stressors project: tracking the community response of planktonic Foraminifera to historical climate change’Posts Tagged 'individualmodeling'
The Foraminiferal response to climate stressors project: tracking the community response of planktonic Foraminifera to historical climate change
Published 14 June 2022 Science ClosedTags: individualmodeling, methods, modeling, protists
Ocean acidification effects on aquaculture of a high resilient calcifier species: a bioeconomic approach
Published 1 June 2022 Science ClosedTags: fisheries, individualmodeling, modeling, mollusks, socio-economy
Highlights
- Farming of high resilience calcifier species was assessed under Ocean Acidification conditions.
- A bioeconomic model with biologic, environmental, product-appearance and market attributes was used.
- Biologic performance and shell integrity features were assumed as pH-dependant functions.
- A negative market price adjustment due to shell spoils because low pH conditions was included.
- The reduction in the sale price due to damaged shell had the highest negative effect on the culture performance.
Abstract
Although Ocean Acidification OA has been identified as a potential threat to calcifying species, recent research has described a wide variety of possible responses (from vulnerability to high resilience) of these species to OA,. Hence, possible OA effects may be more complex, species-specific, and life-stage related than previously thought. Therefore, research of OA effects on aquaculture should address these complexities even when farming high resilience species. This work used bioeconomic modeling to assess the possible effects of OA on bivalve aquaculture incorporating biological, appearance, and market complexities into the culture analysis. A single batch of cultured mussels was modeled from stocking to harvest. The applied bioeconomic model assumed biological (i.e. growth and mortality rates) and shell integrity features (i.e. physical appearance) as pH functions. Bioeconomic parameters were calibrated based on literature regarding the farming of Mytilus galloprovincialis. The model included a negative market price adjustment due to shell spoils developed because of low pH conditions. The bioeconomic performance effects of the pH-driven features on the farming were assessed in a one by one (i.e. individual changes occurring alone) and jointly based analyses (i.e. all the pH-driven changes occurring together). Two IPCC scenarios were used to forecast future diminishing pH trajectories. Results showed that the reduction in the sale price due to damaged shell surface had the highest negative effect on the culture quasi-profits (35% and 70%). When the assumed pH-driven changes were assessed occurring together the quasi-profits diminished up to 49% and 84% in the analyzed OA scenarios. Nevertheless, in all the assessed scenarios positive quasi-profits were achieved. Finally, some proactive measures to diminish the possible effects of OA on bivalves farming are discussed.
Continue reading ‘Ocean acidification effects on aquaculture of a high resilient calcifier species: a bioeconomic approach’Assessing the effects of ocean warming and acidification on the seagrass Thalassia hemprichii
Published 27 May 2022 Science ClosedTags: biological response, growth, individualmodeling, laboratory, mesocosms, modeling, multiple factors, North Pacific, phanerogams, photosynthesis, physiology, sediment, temperature
Seagrass beds serve as important carbon sinks, and it is thought that increasing the quantity and quality of such sinks could help to slow the rate of global climate change. Therefore, it will be important to (1) gain a better understanding of seagrass bed metabolism and (2) document how these high-productivity ecosystems are impacted by climate change-associated factors, such as ocean acidification (OA) and ocean warming (OW). A mesocosm-based approach was taken herein in which a tropical, Western Pacific seagrass species Thalassia hemprichii was cultured under either control or OA-simulating conditions; the temperature was gradually increased from 25 to 31 °C for both CO2 enrichment treatments, and it was hypothesized that this species would respond positively to OA and elevated temperature. After 12 weeks of exposure, OA (~1200 ppm) led to (1) increases in underground biomass and root C:N ratios and (2) decreases in root nitrogen content. Rising temperatures (25 to 31 °C) increased the maximum quantum yield of photosystem II (Fv:Fm), productivity, leaf growth rate, decomposition rate, and carbon sequestration, but decreased the rate of shoot density increase and the carbon content of the leaves; this indicates that warming alone does not increase the short-term carbon sink capacity of this seagrass species. Under high CO2 and the highest temperature employed (31 °C), this seagrass demonstrated its highest productivity, Fv:Fm, leaf growth rate, and carbon sequestration. Collectively, then, it appears that high CO2 levels offset the negative effects of high temperature on this seagrass species. Whether this pattern is maintained at temperatures that actually induce marked seagrass stress (likely beginning at 33–34 °C in Southern Taiwan) should be the focus of future research.
Continue reading ‘Assessing the effects of ocean warming and acidification on the seagrass Thalassia hemprichii’Cessation of hardground accretion by the cold-water coralline algae Clathromorphum compactum and Clathromorphum nereostratum predicted within two centuries
Published 25 May 2022 Science ClosedTags: algae, biological response, BRcommunity, calcification, individualmodeling, laboratory, modeling, multiple factors, North Atlantic, temperature
Ocean acidification and warming are expected to disproportionately affect high-latitude calcifying species, such as crustose coralline algae. Clathromorphum nereostratum and Clathromorphum compactum are the primary builders of carbonate-hardgrounds in the Aleutians Islands of Alaska and North Atlantic shelf, respectively, providing habitat and settlement substrates for a large number of species. We exposed wild-collected specimens to 12 pCO2/T treatments (344–3322 μatm; 6.38–12.40°C) for 4 months in a factorially crossed, replicated laboratory experiment. Impacts of pCO2/T on algal calcification were quantified from linear extension and buoyant weight. Here we show that, despite belonging to the same genus, C. nereostratum exhibited greater sensitivity to thermal stress, while C. compactum exhibited greater sensitivity to pH stress. Furthermore, multivariate models of algal calcification derived from the experiment indicate that both C. nereostratum and C. compactum will commence net dissolution as early as 2120 and 2200 AD, respectively. Our results therefore indicate that near-term climate change may lead to substantial degradation of these species and loss of the critical hardground habitats that they form.
Continue reading ‘Cessation of hardground accretion by the cold-water coralline algae Clathromorphum compactum and Clathromorphum nereostratum predicted within two centuries’Individual-based modeling of shelled pteropods
Published 23 May 2022 Science ClosedTags: abundance, biological response, growth, individualmodeling, modeling, mollusks, mortality, otherprocess, photosynthesis, reproduction, zooplankton
Highlights
- First shelled pteropod individual-based model (IBM) based on Limacinidae species.
- Shelled pteropod IBM reproduces the abundance signal measured at temperate latitudes.
- The pteropod IBM provides the life-stage composition, and life-stage progression of populations.
- IBM might be used for quantifying ongoing and future effects of climate change.
Abstract
Shelled pteropods are cosmopolitan, free-swimming organisms of biogeochemical and commercial importance. They are widely used as sentinel species for the overall response of marine ecosystems to environmental stressors associated with climate change and changes in ocean chemistry. However, currently we are unable to project the effects of climate change on shelled pteropods at the population level, due to the missing spatio-temporal characterization of the response of pteropods to environmental stressors, and the limited information on the pteropod life history and life-cycle. In this study, we implement a shelled pteropod Individual-Based Model (IBM), i.e. we simulate a pteropod population as a set of discrete individuals over several generations, life-stages (eggs, larvae, juveniles and adults) and as a function of temperature, food availability, and aragonite saturation state. The model is able to provide an abundance signal that is consistent with the abundance signal measured in the temperate region. In addition, the modeled life-stage progression matches the reported size spectrum across the year, with two major spawning periods in spring and fall, and maturation in March and September. Furthermore, our IBM correctly predicts the abundance maxima of younger, smaller and potentially more susceptible life-stages in spring and winter. Thus, our model provides a tool for advancing our understanding of the response of pteropod populations to future environmental changes.
Continue reading ‘Individual-based modeling of shelled pteropods’A competitive advantage of middle-sized diatoms from increasing seawater CO2
Published 20 May 2022 Science ClosedTags: growth, individualmodeling, modeling, phytoplankton
Diatoms, one of the most important phytoplankton groups, fulfill their carbon demand from seawater mainly by obtaining passively diffused carbon dioxide (CO2) and/or actively consuming intracellular energy to acquire bicarbonate (HCO3–). An anthropogenically induced increase in seawater CO2 reduces the HCO3– requirement of diatoms, potentially saving intracellular energy and benefitting their growth. This effect is commonly speculated to be most remarkable in larger diatoms that are subject to a stronger limitation of CO2 supply because of their smaller surface-to-volume ratios. However, we constructed a theoretical model for diatoms and revealed a unimodal relationship between the simulated growth rate response (GRR, the ratio of growth rates under elevated and ambient CO2) and cell size, with the GRR peaking at a cell diameter of ∼7 μm. The simulated GRR of the smallest diatoms was low because the CO2 supply was nearly sufficient at the ambient level, while the decline of GRR from a cell diameter of 7 μm was simulated because the contribution of seawater CO2 to the total carbon demand greatly decreased and diatoms became less sensitive to CO2 increase. A collection of historical data in CO2 enrichment experiments of diatoms also showed a roughly unimodal relationship between maximal GRR and cell size. Our model further revealed that the “optimal” cell size corresponding to peak GRR enlarged with the magnitude of CO2 increase but diminished with elevating cellular carbon demand, leading to projection of the smallest optimal cell size in the equatorial Pacific upwelling zone. Last, we need to emphasize that the size-dependent effects of increasing CO2 on diatoms are multifaceted, while our model only considers the inorganic carbon supply from seawater and optimal allocation of intracellular energy. Our study proposes a competitive advantage of middle-sized diatoms and can be useful in projecting changes in the diatom community in the future acidified high-CO2 ocean.
Continue reading ‘A competitive advantage of middle-sized diatoms from increasing seawater CO2’Multiscale mechanical consequences of ocean acidification for cold-water corals
Published 19 May 2022 Science ClosedTags: biological response, BRcommunity, corals, dissolution, individualmodeling, laboratory, modeling, North Atlantic, North Pacific
Ocean acidification is a threat to deep-sea corals and could lead to dramatic and rapid loss of the reef framework habitat they build. Weakening of structurally critical parts of the coral reef framework can lead to physical habitat collapse on an ecosystem scale, reducing the potential for biodiversity support. The mechanism underpinning crumbling and collapse of corals can be described via a combination of laboratory-scale experiments and mathematical and computational models. We synthesise data from electron back-scatter diffraction, micro-computed tomography, and micromechanical experiments, supplemented by molecular dynamics and continuum micromechanics simulations to predict failure of coral structures under increasing porosity and dissolution. Results reveal remarkable mechanical properties of the building material of cold-water coral skeletons of 462 MPa compressive strength and 45–67 GPa stiffness. This is 10 times stronger than concrete, twice as strong as ultrahigh performance fibre reinforced concrete, or nacre. Contrary to what would be expected, CWCs retain the strength of their skeletal building material despite a loss of its stiffness even when synthesised under future oceanic conditions. As this is on the material length-scale, it is independent of increasing porosity from exposure to corrosive water or bioerosion. Our models then illustrate how small increases in porosity lead to significantly increased risk of crumbling coral habitat. This new understanding, combined with projections of how seawater chemistry will change over the coming decades, will help support future conservation and management efforts of these vulnerable marine ecosystems by identifying which ecosystems are at risk and when they will be at risk, allowing assessment of the impact upon associated biodiversity.
Continue reading ‘Multiscale mechanical consequences of ocean acidification for cold-water corals’Influence of climate on seawater quality and green mussel production
Published 12 May 2022 Science ClosedTags: biogeochemistry, biological response, field, fisheries, individualmodeling, modeling, mollusks, North Pacific
This study aimed to investigate the relationships between atmospheric parameters, seawater quality and green mussel production which were cultured in pond, estuary and coastal areas. Seawater and mussel samples were collected from mussel farms in the inner Gulf of Thailand from January to December 2019. Climate data were obtained from the Thai Meteorological Department. The correlations between selected atmospheric and seawater parameters were developed using linear and non-linear models. The influence of seawater quality on mussel production was evaluated using principal component analysis and stepwise multiple linear regression. The effects of atmospheric variation on green mussel productivity were simulated. The results showed that high air temperature and rainfall caused an increase in seawater temperature and a decrease in salinity, respectively. It was observed that the most influential factors affecting mussel production were nutrients and dissolved oxygen in ponds, temperature and salinity in estuaries, and nutrients and pH in coastal areas. The simulation indicated that mussel production can deteriorate when air temperature reaches 34°C and rainfall is higher than 200 mm per month. Our results suggest that under climate change events, locations with less riverine influence can provide higher mussel productivity. These results can be used as a guideline for farmers during a climate change event.
Continue reading ‘Influence of climate on seawater quality and green mussel production’Ocean futures for the world’s largest yellowfin tuna population under the combined effects of ocean warming and acidification
Published 28 April 2022 Science ClosedTags: biological response, fish, fisheries, individualmodeling, modeling, mortality, North Pacific, policy, reproduction, socio-economy, South Pacific
The impacts of climate change are expected to have profound effects on the fisheries of the Pacific Ocean, including its tuna fisheries, the largest globally. This study examined the combined effects of climate change on the yellowfin tuna population using the ecosystem model SEAPODYM. Yellowfin tuna fisheries in the Pacific contribute significantly to the economies and food security of Pacific Island Countries and Territories and Oceania. We use an ensemble of earth climate models to project yellowfin populations under a high greenhouse gas emissions (IPCC RCP8.5) scenario, which includes, the combined effects of a warming ocean, increasing acidification and changing ocean chemistry. Our results suggest that the acidification impact will be smaller in comparison to the ocean warming impact, even in the most extreme ensemble member scenario explored, but will have additional influences on yellowfin tuna population dynamics. An eastward shift in the distribution of yellowfin tuna was observed in the projections in the model ensemble in the absence of explicitly accounting for changes in acidification. The extent of this shift did not substantially differ when the three-acidification induced larval mortality scenarios were included in the ensemble; however, acidification was projected to weaken the magnitude of the increase in abundance in the eastern Pacific. Together with intensive fishing, these potential changes are likely to challenge the global fishing industry as well as the economies and food systems of many small Pacific Island Countries and Territories. The modelling framework applied in this study provides a tool for evaluating such effects and informing policy development.
Continue reading ‘Ocean futures for the world’s largest yellowfin tuna population under the combined effects of ocean warming and acidification’Dynamic energy budget modeling of Atlantic surfclam, Spisula solidissima, under future ocean acidification and warming
Published 7 April 2022 Science ClosedTags: biological response, BRcommunity, individualmodeling, laboratory, modeling, mollusks, morphology, multiple factors, North Atlantic, physiology, reproduction, temperature
Highlights
- Surfclams were exposed to OA levels inducing effects on physiological rates
- A DEB model was calibrated integrating effects on ingestion and maintenance costs
- The model was validated on Georges Bank and Mid-Atlantic Bight population data
- Effects of future OA and warming conditions projected by RCP scenarios were simulated
- Under high pCO2 emissions, DEB projects effects on growth and reproduction by 2100
Abstract
A dynamic energy budget (DEB) model integrating pCO2 was used to describe ocean acidification (OA) effects on Atlantic surfclam, Spisula solidissima, bioenergetics. Effects of elevated pCO2 on ingestion and somatic maintenance costs were simulated, validated, and adapted in the DEB model based upon growth and biological rates acquired during a 12-week laboratory experiment. Temperature and pCO2 were projected for the next 100 years following the intergovernmental panel on climate change representative concentration pathways scenarios (2.6, 6.0, and 8.5) and used as forcing variables to project surfclam growth and reproduction. End-of-century water warming and acidification conditions resulted in simulated faster growth for young surfclams and more energy allocated to reproduction until the beginning of the 22nd century when a reduction in maximum shell length and energy allocated to reproduction was observed for the RCP 8.5 scenario.
Continue reading ‘Dynamic energy budget modeling of Atlantic surfclam, Spisula solidissima, under future ocean acidification and warming’Modelling antifouling compounds of macroalgal holobionts in current and future pH conditions
Published 7 March 2022 Science ClosedTags: algae, biological response, individualmodeling, modeling, prokaryotes, protists
Marine macroalgae are important ecosystem engineers in marine coastal habitats. Macroalgae can be negatively impacted through excessive colonization by harmful bacteria, fungi, microalgae, and macro-colonisers and thus employ a range of chemical compounds to minimize such colonization. Recent research suggests that environmental pH conditions potentially impact the functionality of such chemical compounds. Here we predict if and how naturally fluctuating pH conditions and future conditions caused by ocean acidification will affect macroalgal (antifouling) compounds and thereby potentially alter the chemical defence mediated by these compounds. We defined the relevant ecological pH range, analysed and scored the pH-sensitivity of compounds with antifouling functions based on their modelled chemical properties before assessing their distribution across the phylogenetic macroalgal groups, and the proportion of sensitive compounds for each investigated function. For some key compounds, we also predicted in detail how the associated ecological function may develop across the pH range. The majority of compounds were unaffected by pH, but compounds containing phenolic and amine groups were found to be particularly sensitive to pH. Future pH changes due to predicted average open ocean acidification pH were found to have little effect. Compounds from Rhodophyta were mainly pH-stable. However, key algal species amongst Phaeophyceae and Chlorophyta were found to rely on highly pH-sensitive compounds for their chemical defence against harmful bacteria, microalgae, fungi, and biofouling by macro-organisms. All quorum sensing disruptive compounds were found the be unaffected by pH, but the other ecological functions were all conveyed in part by pH-sensitive compounds. For some ecological keystone species, all of their compounds mediating defence functions were found to be pH-sensitive based on our calculations, which may not only affect the health and fitness of the host alga resulting in host breakdown but also alter the associated ecological interactions of the macroalgal holobiont with micro and macrocolonisers, eventually causing ecosystem restructuring and the functions (e.g. habitat provision) provided by macroalgal hosts. Our study investigates a question of fundamental importance because environments with fluctuating or changing pH are common and apply not only to coastal marine habitats and estuaries but also to freshwater environments or terrestrial systems that are subject to acid rain. Hence, whilst warranting experimental validation, this investigation with macroalgae as model organisms can serve as a basis for future investigations in other aquatic or even terrestrial systems.
Continue reading ‘Modelling antifouling compounds of macroalgal holobionts in current and future pH conditions’The impact of oyster aquaculture on the estuarine carbonate system
Published 2 March 2022 Science ClosedTags: biological response, calcification, individualmodeling, modeling, mollusks, morphology, North Atlantic, physiology, respiration
Many studies have examined the vulnerability of calcifying organisms, such as the eastern oyster (Crassostrea virginica), to externally forced ocean acidification, but the opposite interaction whereby oysters alter their local carbonate conditions has received far less attention. We present an exploratory model for isolating the impact that net calcification and respiration of aquacultured eastern oysters can have on calcite and aragonite saturation states, in the context of varying temperature, ocean-estuary mixing, and air-sea gas exchange. We apply the model to the Damariscotta River Estuary in Maine which has experienced rapid expansion of oyster aquaculture in the last decade. Our model uses oyster shell growth over the summer season and a previously derived relationship between net calcification and respiration to quantify impacts of net oyster calcification and gross metabolism on carbonate saturation states in open tidal waters. Under 2018 industry size and climate conditions, we estimate that oysters can lower carbonate saturation states by up to 5% (i.e., 0.17 and 0.11 units on calcite and aragonite saturation states, respectively) per day in late summer, with an average of 3% over the growing season. Perturbations from temperature and air-sea exchange are similar in magnitude. Under 2050 climate conditions and 2018 industry size, calcite saturation state will decrease by up to an additional 0.54 units. If the industry expands 3-fold by 2050, the calcite and aragonite saturation states may decrease by 0.73 and 0.47 units, respectively, on average for the latter half of the growing season when compared to 2018 climate conditions and industry size. Collectively, our results indicate that dense aggregations of oysters can have a significant role on estuarine carbonate chemistry.
Continue reading ‘The impact of oyster aquaculture on the estuarine carbonate system’Chemical speciation models based upon the pitzer activity coefficient equations, including the propagation of uncertainties: artificial seawater from 0 to 45 °C
Published 1 March 2022 Science ClosedTags: individualmodeling, modeling
Accurate chemical speciation models of solutions containing the ions of seawater have applications in the calculation of carbonate system equilibria and trace metal speciation in natural waters, and the determination of pH. Existing models, based on the Pitzer formalism for the calculation of activity coefficients, do not yet agree with key experimental data (potentiometric determinations of H+ and Cl− activity products in acidified artificial seawaters) and, critically, do not include uncertainty estimates. This hampers applications of the models, and also their further development (for which the uncertainty contributions of individual ion interactions and equilibrium constants need to be known). We have therefore implemented the models of Waters and Millero (Mar. Chem. 149, 8-22, 2013) and Clegg and Whitfield (Geochim. et Cosmochim. Acta 59, 2403-2421, 1995) for artificial seawater, within a generalised treatment of uncertainties, as a first step towards a more complete model of standard seawater and pH buffers. This addition to the model enables both the total uncertainty of any model-calculated quantity (e.g., pH, speciation) to be estimated, and also the contributions of all interaction parameters and equilibrium constants. Both models have been fully documented (and some corrections made). Estimates of the variances and covariances of the interaction parameters were obtained by Monte Carlo simulation, with simplifying assumptions. The models were tested against measured electromotive forces (EMFs) of cells containing acidified artificial seawaters. The mean offsets (measured – calculated) at 25 °C for the model of Waters and Millero are: 0.046 ± 0.11 mV (artificial seawater without sulphate, 0.280 mol kg−1 to 0.879 mol kg−1 ionic strength); and − 0.199 ± 0.070 mV (artificial seawater, salinities 5 to 45). Results are similar at other temperatures. These differences compare with an overall uncertainty in the measured EMFs of about 0.04 mV. Total uncertainties for calculated EMFs of the solutions were dominated by just a few contributions: mainly H+-Cl−, Na+-Cl−, and H+-Na+-Cl− ionic interactions, and the thermodynamic dissociation constant of HSO4−. This makes it likely that the accuracy of the models can readily be improved, and recommendations for further work are made. It is shown that standard EMFs used in the calibration of the marine ‘total’ pH scale can be accurately predicted with only slight modification to the original models, suggesting that they can contribute to the extension of the scale to lower salinities.
Continue reading ‘Chemical speciation models based upon the pitzer activity coefficient equations, including the propagation of uncertainties: artificial seawater from 0 to 45 °C’On the effects of temperature and pH on tropical and temperate holothurians
Published 8 February 2022 Science ClosedTags: biological response, echinoderms, individualmodeling, laboratory, modeling, morphology, multiple factors, performance, physiology, reproduction, temperature
Ocean acidification and increased ocean heat content has direct and indirect effects on marine organisms such as holothurians (sea cucumbers) that are vulnerable to changes in pH and temperature. These environmental factors have the potential to influence organismal performance and fitness at different life stages. Tropical and temperate holothurians are more vulnerable to temperature and pH than those from colder water environments. The high level of environmental variation observed in the oceans could influence organismal responses and even produce a wide spectrum of compensatory physiological mechanisms. It is possible that in these areas, larval survival will decline by up to 50% in response to a reduction of 0.5 pH units. Such reduction in pH may trigger low intrinsic growth rates and affect the sustainability of the resource. Here we describe the individual and combined effects that temperature and pH could produce in these organisms. We also describe how these effects can scale from individuals to the population level by using age-structured spatial models in which depensation can be integrated. The approach shows how physiology can improve the conservation of the resource based on the restriction of growth model parameters and by including a density threshold, below which the fitness of the population, specifically intrinsic growth rate, decreases.
Continue reading ‘On the effects of temperature and pH on tropical and temperate holothurians’Evaluation of the impacts of climate change on the distribution of Florida stone crab larvae on the West Florida Shelf
Published 4 January 2022 Science ClosedTags: biological response, crustaceans, individualmodeling, laboratory, modeling, North Atlantic, reproduction
Ocean acidification and ocean warming are the two components of climate change that impacts marine life the most. The commercially important Florida stone crab, Menippe mercenaria, is one of the species that is going to be affected by those changes. In this study we investigated the impacts of climate change on the distribution of the stone crab larvae on the West Florida Shelf. To understand the dispersion of the larvae, we coupled SLIM3D, a multi-scale ocean model, with a larval dispersal model. We then conducted a connectivity study and evaluated the impacts of climate change analyzing three different scenarios, one presenting the dispersion of the larvae for present conditions and the two others presenting the dispersion for mild and extreme climate change. The results show a clear impact of climate change on larval dispersal and on the subsequent crabs distribution. In the future, climate change could result in stone crabs moving north or to deeper waters. The second impact would be the increase in the number of larvae settling in the non-fishing zone, where the water depth exceeds 30 m. The distance traveled by larvae is going to decrease, resulting in an increase of self-recruitment and decrease of the size of sub-populations. The last impact we identified is the possibility of a shift of the spawning period earlier in the season. We also evaluated that the habitats in the non-fishing zone cannot serve as a significant source of larvae for the habitats in the fishing zone since there is very little exchange between the two zones. Overall, this work could help local authorities to better understand M. mercenaria and to take actions regarding the fishery management and its future considering the upcoming changes in the ocean conditions.
Continue reading ‘Evaluation of the impacts of climate change on the distribution of Florida stone crab larvae on the West Florida Shelf’Carbonate chemistry in the microenvironment within cyanobacterial aggregates under present-day and future pCO2 levels
Published 29 December 2021 Science ClosedTags: Baltic, biological response, BRcommunity, individualmodeling, laboratory, modeling, prokaryotes
Photosynthesis and respiration cause distinct chemical microenvironments within cyanobacterial aggregates. Here, we used microsensors and a diffusion–reaction model to characterize gradients in carbonate chemistry and investigate how these are affected by ocean acidification in Baltic vs. Pacific aggregates (Nodularia and Dolichospermum vs. Trichodesmium). Microsensor measurements of O2 and pH were performed under in situ and expected future pCO2 levels on Nodularia and Dolichospermum aggregates collected in the Baltic Sea. Under in situ conditions, O2 and pH levels within the aggregates covered ranges of 80–175% air saturation and 7.7–9.4 in dark and light, respectively. Carbon uptake in the light was predicted to reduce HCO3− by 100–150 μmol L−1 and CO2 by 3–6 μmol L−1 in the aggregate center compared to outside, inducing strong CO2 depletion (down to 0.5 μmol L−1 CO2 remaining in the center) even when assuming that HCO3− covered 80–90% of carbon uptake. Under ocean acidification conditions, enhanced CO2 availability allowed for significantly lower activity of carbon concentrating mechanisms, including a reduction of the contribution of HCO3− to carbon uptake by up to a factor of 10. The magnification of proton gradients under elevated pCO2 that was predicted based on a lower buffer capacity was observed in measurements despite a concurrent decrease in photosynthetic activity. In summary, we provide a quantitative image of the inorganic carbon environment in cyanobacterial aggregates under present-day and expected future conditions, considering both the individual and combined effects of the chemical and biological processes that shape these environments.
Continue reading ‘Carbonate chemistry in the microenvironment within cyanobacterial aggregates under present-day and future pCO2 levels’Modelling ocean acidification effects with life stage-specific responses alters spatiotemporal patterns of catch and revenues of American lobster, Homarus americanus
Published 15 December 2021 Science ClosedTags: biological response, BRcommunity, crustaceans, fisheries, individualmodeling, laboratory, mitigation, modeling, morphology, mortality, North Pacific, physiology, reproduction, socio-economy
Ocean acidification (OA) affects marine organisms through various physiological and biological processes, yet our understanding of how these translate to large-scale population effects remains limited. Here, we integrated laboratory-based experimental results on the life history and physiological responses to OA of the American lobster, Homarus americanus, into a dynamic bioclimatic envelope model to project future climate change effects on species distribution, abundance, and fisheries catch potential. Ocean acidification effects on juvenile stages had the largest stage-specific impacts on the population, while cumulative effects across life stages significantly exerted the greatest impacts, albeit quite minimal. Reducing fishing pressure leads to overall increases in population abundance while setting minimum size limits also results in more higher-priced market-sized lobsters (> 1 lb), and could help mitigate the negative impacts of OA and concurrent stressors (warming, deoxygenation). However, the magnitude of increased effects of climate change overweighs any moderate population gains made by changes in fishing pressure and size limits, reinforcing that reducing greenhouse gas emissions is most pressing and that climate-adaptive fisheries management is necessary as a secondary role to ensure population resiliency. We suggest possible strategies to mitigate impacts by preserving important population demographics.
Continue reading ‘Modelling ocean acidification effects with life stage-specific responses alters spatiotemporal patterns of catch and revenues of American lobster, Homarus americanus’Ocean acidification reduces the growth of two Southern Ocean phytoplankton
Published 24 November 2021 Science ClosedTags: Antarctic, BRcommunity, individualmodeling, laboratory, light, modeling, morphology, multiple factors, photosynthesis, physiology, phytoplankton, temperature
Model projections for the Southern Ocean indicate that light, iron (Fe) availability, temperature and carbon dioxide (CO2) will change concurrently in the future. We investigated the physiological responses of Southern Ocean phytoplankton to multiple variables by culturing the haptophyte Phaeocystis antarctica and the diatom Chaetoceros flexuosus under various combinations of light, Fe, temperature and CO2. Using statistical models, the influence of each environmental variable was analysed for each physiological response, ultimately predicting how ‘future’ conditions (high temperature and high CO2) influenced the two phytoplankton species. Under future conditions, cellular chlorophyll a and carbon to nitrogen molar ratios were modelled to increase for both species, in all light and Fe treatments, but at times were inconsistent with measured values. Measured and modelled values of the photochemical efficiency of photosystem II (Fv/Fm) declined in cultures of P. antarctica due to concurrent increases in temperature and CO2, under all light and Fe treatments. The trends in Fv/Fm for C. flexuosus were less clear. Our model and observations suggest that when temperature and CO2 are concurrently increased, the growth of both species remains largely unchanged. This modelling analysis reveals that high CO2 exerts a strong negative influence on the growth of both phytoplankton, and any ‘future’ increase in growth can be attributed to the positive effect of warming rather than a CO2 fertilisation effect.
Continue reading ‘Ocean acidification reduces the growth of two Southern Ocean phytoplankton’Predictive model for gross community production rate of coral reefs using ensemble learning methodologies
Published 19 November 2021 Science ClosedTags: biogeochemistry, calcification, chemistry, communitymodeling, corals, education, individualmodeling, modeling, respiration
Coral reefs play a vital role in maintaining the ecological balance of the marine ecosystem. Various marine organisms depend on coral reefs for their existence and their natural processes. Coral reefs provide the necessary habitat for reproduction and growth for various exotic species of the marine ecosystem. In this article, we discuss the most important parameters which influence the lifecycle of coral and coral reefs such as ocean acidification, deoxygenation and other physical parameters such as flow rate and surface area. Ocean acidification depends on the amount of dissolved Carbon dioxide (CO2). This is due to the release of H+ ions upon the reaction of the dissolved CO2 gases with the calcium carbonate compounds in the ocean. Deoxygenation is another problem that leads to hypoxia which is characterized by a lesser amount of dissolved oxygen in water than the required amount for the existence of marine organisms. In this article, we highlight the importance of physical parameters such as flow rate which influence gas exchange, heat dissipation, bleaching sensitivity, nutrient supply, feeding, waste and sediment removal, growth and reproduction. In this paper, we also bring out these important parameters and propose an ensemble machine learning-based model for analyzing these parameters and provide better rates that can help us to understand and suitably improve the ocean composition which in turn can eminently improve the sustainability of the marine ecosystem, mainly the coral reefs
Continue reading ‘Predictive model for gross community production rate of coral reefs using ensemble learning methodologies’Seasonality and life history complexity determine vulnerability of Dungeness crab to multiple climate stressors
Published 11 October 2021 Science ClosedTags: chemistry, crustaceans, fisheries, individualmodeling, mitigation, modeling, North Pacific, policy, regionalmodeling, reproduction, review
Abstract
Scaling climate change impacts from individual responses to population-level vulnerability is a pressing challenge for scientists and society. We assessed vulnerability of the most valuable fished species in the Northwest U.S.—Dungeness crab—to climate stressors using a novel combination of ocean, population, and larval transport models with stage-specific consequences of ocean acidification, hypoxia, and warming. Integration across pelagic and benthic life stages revealed increased population-level vulnerability to each stressor by 2100 under RCP 8.5. Under future conditions, chronic vulnerability to low pH emerged year-round for all life stages, whereas vulnerability to low oxygen continued to be acute, developing seasonally and impacting adults, which are critical to population growth. Our results demonstrate how ontogenetic habitat shifts and seasonal ocean conditions interactively impact population-level vulnerability. Because most valuable U.S. fisheries rely on species with complex life cycles in seasonal seas, chronic and acute perspectives are necessary to assess population-level vulnerability to climate change.
Plain Language Summary
The release of carbon dioxide (CO2) into the atmosphere by human activities is altering ocean conditions including pH, oxygen, and temperature. One way to understand how these changing conditions will affect ecologically, economically, and culturally important marine species is to scale individual responses from laboratory experiments to population-level impacts. In this study, we assessed the vulnerability of Dungeness crab, one of the most valuable fisheries in the NW USA, to stressful conditions based on the predicted habitat exposure and response of each life stage (eggs, larvae, juveniles, and adults). The degree of vulnerability was determined by the seasonality of the ocean conditions in combination with the crab’s complex life cycle. This approach revealed that Dungeness crab life stages and populations will be more vulnerable to low pH, low oxygen, and high temperature in the future (year 2100) under an aggressive CO2 emissions scenario. Based on these results, we recommend that fishery managers incorporate changing conditions into their decision-making to protect vulnerable life stages in areas prone to stressful conditions (e.g., adult crabs in hypoxic areas). Our approach can be adapted for many other economically and ecologically important marine species in order to inform conservation and management strategies.
Continue reading ‘Seasonality and life history complexity determine vulnerability of Dungeness crab to multiple climate stressors’
