Marine ecosystems are undergoing rapid transformation under climate change, yet the responses of many marine invertebrates remain vastly understudied. In particular, for many benthic gastropods there is a striking imbalance between their traditional appreciation by shell collectors—and, consequently, their consistent representation in Natural History Collections—and the limited attention they receive in ecological and conservation studies. Focusing on the northeastern Atlantic and the Mediterranean, the cowries Luria lurida, Naria spurca, Zonaria pyrum and the frog-shell Talisman scrobilator are emblematic examples of this knowledge gap, despite being frequently mentioned as species of conservation concern. Using long-term occurrence records spanning more than a century, we modelled past and present distributions of these species and explored their potential responses to future climate scenarios through a multi-temporal Species Distribution Modelling framework. Our results show that intermediate climatic conditions—both in time (2050–2060 vs. 2090–2100) and scenario intensity (moderate SSP2-4.5 versus high-emission SSP5-8.5)—may represent a critical transition phase, leading to habitat contractions without compensatory gains in newly emerging suitable areas. The Mediterranean Sea is expected to increasingly function as a cul-de-sac, with the dominant circulation patterns strongly limiting outward movements towards cooler regions for species relying on planktic larvae for dispersal. Furthermore, incorporating larval sensitivity to reduced pH suggests that large areas of the Atlantic Ocean may actually result unsuitable for larval persistence, substantially reducing the habitat effectively available for completion of the full life cycle; this highlights the need to account for connectivity, life-history constraints and juvenile-stage sensitivity when assessing climate-driven range shifts in shelled organisms with planktic larvae.
Continue reading ‘Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?’Posts Tagged 'communitymodeling'
Will the Mediterranean sea be a cul-de-sac for marine gastropods under climate change?
Published 23 June 2026 Science Leave a CommentTags: biological response, BRcommunity, communitymodeling, individualmodeling, Mediterranean, modeling, mollusks, North Atlantic, physiology, reproduction
Darkness and body size shaped end-Cretaceous marine extinction patterns
Published 29 May 2026 Science ClosedTags: communitymodeling, modeling, paleo, phytoplankton
The Chicxulub asteroid impact at the Cretaceous–Paleogene (K–Pg) boundary (66 Ma) is thought to have caused the extinction of around 75% of species in the fossil record by triggering catastrophic environmental changes1. However, despite decades of research, the mechanisms linking the environmental changes to the selective extinction patterns observed in the marine fossil record remain unresolved. Here we use a global trait-based ecosystem model2,3 to establish this causality for the marine plankton community beyond the fossilized groups. Our model simulates diversity dynamics during the initial 100 years after the K–Pg boundary and represents explicitly extinction based on biomass thresholds that scales with body size. Under K–Pg climatic forcings, the model reproduces successfully key observed extinction patterns, including the high vulnerability of planktic foraminifera and other zooplankton, the survival of small mixotrophs4 and phytoplankton5,6, and potential for reduced diversity loss in high-latitude settings7. Our analysis suggests that impact-driven darkness and body-size-dependent extinction thresholds drove most of the observed extinction patterns. These results suggest that plankton ecologies enhance survival through differences in energy demand and acquisition. Our study bridges the gap between fossil evidence of extinction patterns and the K–Pg impact winter hypothesis, highlighting the value of trait-based models for understanding past biodiversity crises.
Continue reading ‘Darkness and body size shaped end-Cretaceous marine extinction patterns’The economic impact of climate change on coral reef in the Main Hawaiian Islands
Published 18 March 2026 Science ClosedTags: biological response, communitymodeling, corals, modeling, multiple factors, North Pacific, socio-economy, temperature
Coral reefs are highly diverse and productive ecosystems that provide a wide range of ecosystem services, including recreation, coastal protection, and marine biodiversity. Climate change impacts, including ocean warming and acidification, pose a significant threat to coral reefs and the ecosystem services they provide. The variability of these impacts underlines the need to develop more spatially explicit tools in coastal ecosystem management that integrate and assess potential ecological and socio-economic outcomes. To address this, a spatially explicit predictive ecological model is applied to project changes in coral reef cover, using downscaled data from Shared Socioeconomic Pathway (SSP) climate scenarios. Based on these projections, welfare impacts of changes in recreational value are estimated across different populations and landscapes. Cumulative welfare losses for Hawaiʻi residents range from $1.5 to $3.3 billion in 2024$ by 2100. Counterintuitively, cumulative welfare losses are higher under optimistic emissions scenarios, where coral reef degradation is less severe than higher emission scenarios, because more people will experience smaller ecological losses. The approach incorporates site-specific characteristics, income distribution, and projected regional population growth to connect ecological change with welfare outcomes. EJScreen is used to assess variation in welfare impacts, identifying disadvantaged communities based on demographic and environmental indicators such as poverty, minority status, and exposure to environmental risks. These findings can inform policy and resource allocation by supporting ecosystem management strategies that account for both ecological dynamics and community-level socio-economic conditions.
Continue reading ‘The economic impact of climate change on coral reef in the Main Hawaiian Islands’Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification
Published 12 March 2026 Science ClosedTags: adaptation, biological response, BRcommunity, calcification, communitymodeling, growth, modeling, mortality, otherprocess, performance, phytoplankton, primary production, zooplankton
Increasing emissions of CO2 into the atmosphere are causing ocean acidification, threatening calcifying organisms. In this study, we model the physiological responses of coccolithophorids to acidification to understand the ecological and evolutionary outcomes of a system in interaction with zooplankton. Assuming a trade-off between growth and protection against grazing, we show that calcification has bivalent effects on transfers between two trophic levels and that acidity can strongly alter energy transfers. Taking into account the evolution of calcifying phenotypes in response to acidification, we show that the system outcome contrasts with previous results. While the effect of evolution depends on how calcification affects grazing, it nevertheless follows that acidification leads to a decrease in calcifying capacity. This evolutionary decrease may be progressive, but can also lead to tipping points where abrupt shifts may occur. Such a counter-selection of calcification in turn affects ecosystem functioning, enhancing energy transfers within the system and modifying carbon fluxes. We discuss how such eco-evolutionary changes may impact food webs integrity, carbon sequestration into the deep ocean and therefore endanger the carbon pump stability.
Continue reading ‘Eco-evolutionary dynamics of planktonic calcifying communities under ocean acidification’Modeling the spatiotemporal effects of ocean acidification and warming on Atlantic sea scallop growth to guide adaptive fisheries management
Published 7 January 2026 Science ClosedTags: biological response, communitymodeling, fisheries, modeling, mollusks, morphology, multiple factors, North Atlantic, temperature
Highlights
- We spatially couple a scallop bioenergetic model to a regional oceanographic model.
- Our model reproduces observed growth patterns using temperature, food, and pCO2.
- Mid-century warming enhances scallop growth except in the south.
- By 2100, scallops grow faster but reach smaller sizes under warming and acidification.
- This tool can inform adaptive fisheries management under climate change.
Abstract
Climate-ready fisheries management requires reliable predictions of species responses to changing conditions across large-scale environmental gradients. Bioenergetic frameworks, such as Dynamic Energy Budget (DEB) models, relate physiological processes to environmental conditions, enabling predictions of organismal growth under projected climate change conditions. Here, we provide the first large-scale coupling of a DEB model to downscaled regional oceanographic simulations to resolve spatiotemporal changes and reveal how climate stressors emerge at relevant biogeographic, economic, and oceanographic scales. We calibrated our DEB model for the Atlantic sea scallop (Placopecten magellanicus) with forcing from a realistic oceanographic and biogeochemical model for the Northeast U.S. continental shelf to predict the effects of ocean acidification (OA) and warming on individual growth historically and over the next century. Our model reproduced observed historical patterns in scallop age at harvest size and maximum size. At mid-century (2035–2050), scallop growth was projected to increase in most areas except the southern Mid-Atlantic, and OA effects were limited to the deep Gulf of Maine. By the end of the century (2080–2095) under a high emissions scenario, scallops were predicted to grow faster but attain smaller maximum sizes. Our results highlight that warming stress is more acute than previously accounted for, particularly in the southern Mid-Atlantic. While warming stress emerges in the south first, OA stress emerges before warming in the north. Together, these emerging stressors compress the spatial range for optimal growth. Altogether, our findings demonstrate the utility of the spatially coupled DEB model as a tool to inform adaptive fisheries management.
Continue reading ‘Modeling the spatiotemporal effects of ocean acidification and warming on Atlantic sea scallop growth to guide adaptive fisheries management’Dynamics of a coral reef system under climate change
Published 28 November 2025 Science ClosedTags: biological response, BRcommunity, communitymodeling, corals, echinoderms, modeling, multiple factors, temperature
Highlights
- It is established that a new a stochastic coral-starfish model with global warming and ocean acidification.
- It is revealed that the change in global warming has a decisive impact on the dominant position of corals and starfish.
- It is found that the variation of pH is able to destabilize coral-starfish interactions.
Abstract
The intensification of global warming and ocean acidification are important factors affecting coral reef degradation, however, their impact mechanisms on coral reef system are still unclear. In this paper, we study the dynamics of a stochastic coral-starfish model considering the factors of global warming and ocean acidification, where the stochastic environmental fluctuation is characterized by mean-reverting Ornstein-Uhlenbeck (OU) process. A key advantage of considering global warming and ocean acidification in coral reef systems is that it can accurately describe the dynamic mechanisms of coral-starfish interactions, providing a scientifically reliable theoretical basis for exploring the evolutionary succession of coral reef systems. The main purpose of this paper is to investigate how global warming and ocean acidification affect the dynamic mechanisms of coral reef systems in the presence and absence of stochastic disturbances. Mathematically, we mainly study the critical threshold conditions for the transcritical bifurcation, saddle-node bifurcation, and Hopf bifurcation of deterministic coral reef system, as well as the existence of ergodic stationary distribution, precise expressions of probability density function, persistent in the mean, and stochastic extinction dynamics in stochastic coral reef system, which in turn provide a theoretical basis for numerical simulations. Numerical analysis indicates that the variations of global warming and ocean acidification can generate a great influence on the coral-starfish dynamics with and without OU process. Significantly, it is found that coral growth dominates under the increasing global warming effect, while starfish growth dominates under the decreasing global warming effect in a randomly perturbed environment. Furthermore, the change of pH has capacity to destabilize coral-starfish interactions, while the intensified global warming can lead to the extinction of starfish. These findings may contribute to the studies of potential strategies for protecting coral reef ecosystems under the impact of climate change.
Continue reading ‘Dynamics of a coral reef system under climate change’Insights from a changing ocean: evolving biogeochemistry and its impacts on marine ecosystems and climate
Published 13 October 2025 Science ClosedTags: biogeochemistry, chemistry, communitymodeling, field, modeling, paleo, regionalmodeling
Marine biogeochemistry integrates chemical, biological, geological, and physical processes that are fundamental to Earth’s climate and ecosystems. As elements cycle through the ocean, atmosphere, and biosphere, they leave behind biogeochemical fingerprints that serve as proxies to track environmental change. Over the industrial era, anthropogenic CO2 emissions and other human activities have caused the oceans to change rapidly, perturbing this biogeochemical landscape. Characterizing biogeochemical shifts is critical to advance our understanding of climate-driven impacts, assess marine ecosystem health, and evaluate climate solutions. Recent advancements in biogeochemical tools and technologies have deepened our insights into oceanic change. The development of high-precision paleoproxies has extended records of ocean conditions into the pre-industrial era, while the Argo float array has enabled four-dimensional monitoring of biogeochemistry globally. High-resolution numerical modeling has also improved our ability to capture complex interactions at fine spatial and temporal scales, offering a holistic framework to understand anthropogenic impacts from past to future. Together, these technologies provide a comprehensive toolkit to characterize shifts in ocean biogeochemistry in unprecedented detail and advance our understanding of global environmental change. This thesis weaves together applications of novel biogeochemical tools to examine the drivers, impacts, and mitigation strategies of a rapidly changing ocean. Each chapter leverages diverse datasets and multiple tools to provide new insights on ocean change based on marine biogeochemistry. In Chapter 2, I combine boron-isotope measurements from cold-water corals with a biogeochemical model to reconstruct and investigate subsurface acidification trends over the industrial era in the California Current System. In Chapter 3, I combine Argo-based biogeochemical data products, archival tagging records, and machine learning methods to develop a four-dimensional species distribution model for an economically important fishery species, revealing biogeochemical constraints on its migration. In Chapter 4, I employ a high-resolution biogeochemical model of the Salish Sea to evaluate the detectability of ocean alkalinity enhancement, a marine carbon dioxide removal strategy for climate mitigation. These studies provide new frameworks and tools to investigate, monitor, and respond to a changing ocean.
Continue reading ‘Insights from a changing ocean: evolving biogeochemistry and its impacts on marine ecosystems and climate’Identifying and reducing climate uncertainty in fisheries management reference points
Published 15 September 2025 Science ClosedTags: biological response, communitymodeling, crustaceans, fisheries, modeling, socio-economy
Modelling has predicted that reductions in ocean pH and increases in temperature will reduce vital rates (survival and growth) of North Pacific crab stocks and hence the target levels of fishing mortality consistent with sustainable harvesting. However, these predictions have been based on the best estimates of the effects of changes in ocean pH and temperature on vital rates from laboratory experiments. We quantified the effects of several climate and market sources of variability in Alaskan red king and southern Tanner crab fisheries on predicted optimal fishing mortality rates, including changes in ocean chemistry and temperature on vital rates, non-linear relationships between prices, costs and catch, and the uncertainty in population dynamics models. The declines in survival consistently lead to predictions of a reduction in productivity and hence the optimal level of fishing intensity over time, but the extent of change is uncertain. Uncertainty related to the effects of ocean pH and temperature on vital rates and variability among Earth System Models and future emission scenarios are the dominant sources of uncertainty, although potential fluctuations in prices and costs are also consequential. Further, simulations are used to explore the relationship between changes in ocean pH or temperature and vital rates (additional experimental replicates and a wider range of levels of ocean pH in experiments) and hence identify approaches to reduce the uncertainty in estimates of future projections of target fishing mortality rates. Importantly, we demonstrate that optimal approaches to reducing uncertainty depend on life stage (juvenile growth for red king crab and larval survival for southern Tanner crab), and the optimal experiment depends on species (increasing the range of pH levels for red king crab vs increasing sample sizes for southern Tanner crab). The results of this study can inform priorities for future ocean acidification-related laboratory experiments and provide a basis for evaluating “investment in research” more broadly.
Continue reading ‘Identifying and reducing climate uncertainty in fisheries management reference points’Mathematical analysis on the effects of microplastic pollution and ocean acidification on coral reefs in aquatic ecosystem
Published 10 September 2025 Science ClosedTags: biological response, BRcommunity, communitymodeling, corals, modeling, multiple factors, plastics
This study explores the complex interplay between microplastic contamination and ocean acidification in influencing coral reef ecosystems through the development of a mathematical model with time-varying parameters. The model ensures positivity and boundedness to accurately represent ecological dynamics, and stability analyses provide insights into system behavior under various environmental conditions. Numerical simulations validate the theoretical results and reveal that microplastic accumulation in marine environments significantly hinders coral reef establishment while contributing to elevated oceanic carbon dioxide levels. These rising CO2 levels, primarily driven by anthropogenic emissions, lead to accelerated ocean acidification, further degrading coral reefs. Model predictions indicate that, if unchecked, the current trends in microplastic pollution and ocean acidification will result in a 50% reduction in coral reef coverage within four decades. However, the findings suggest that limiting microplastic input into aquatic ecosystems could mitigate these adverse effects, preserving reef health and slowing acidification. By quantifying the relationship between microplastic pollution, ocean acidification, and coral reef dynamics, this study provides a robust framework for understanding and addressing critical threats to marine ecosystems.
Continue reading ‘Mathematical analysis on the effects of microplastic pollution and ocean acidification on coral reefs in aquatic ecosystem’Interactive effects of ocean acidification and warming disrupt calcification and microbiome composition in bryozoans
Published 12 August 2025 Science ClosedTags: abundance, adaptation, biological response, BRcommunity, bryozoa, community composition, communitymodeling, field, Mediterranean, modeling, molecular biology, morphology, mortality, otherprocess, prokaryotes, vents
Marine habitat-forming species provide crucial ecosystem functions and services worldwide. Still, the individual and combined long-term effects of ocean acidification and warming on bryozoan populations, structures, and microbiomes remain unexplored. Here, we investigate the skeletal properties, microbiome shifts, and population trends of two bryozoan species living inside and outside a volcanic CO2 vent, a natural analog to future ocean acidification conditions. We show that bryozoans can acclimatize to acidification by adjusting skeletal properties and maintaining stable microbiomes. However, we document a decrease in microbial genera playing essential functions under acidified conditions. Moreover, we show that ocean acidification exacerbates bryozoan cover loss and mortality caused by ocean warming. The observed shifts in the microbiome and cover suggest that, despite their morphological plasticity, bryozoan species will be heavily impacted by future ocean conditions, posing a threat to many benthic ecosystems in which they play a pivotal role.
Continue reading ‘Interactive effects of ocean acidification and warming disrupt calcification and microbiome composition in bryozoans’Assessing vulnerability of Arctic fish species to climate change
Published 12 August 2025 Science ClosedTags: Arctic, biological response, communitymodeling, fish, modeling, review
Climate change is impacting Arctic marine ecosystems at faster rates than the global average, challenging the management and conservation of biodiversity and living marine resources. This study examined the climate risks and vulnerabilities of 21 Arctic fish species occurring in the western Canadian Arctic using a fuzzy logic approach. Identified climatic hazards to marine species and their habitats are increasing temperature, decreasing sea ice cover, freshening, decreasing oxygen concentration, and acidification. The nature of these hazards included changes in mean conditions by 2050 (2041–2060), compared to the historical period (1979–2015 average) simulated from a regional coupled ice-ocean biogeochemical model and two coupled Earth system models under low and high emissions scenarios. A spatially-explicit algorithm was used to assess the risk and vulnerability in the Beaufort Sea shelf and slope and Amundsen Gulf (BS–AG) based on the species’ biological traits, biogeography and their exposure to climatic hazards. The results indicated high to very high exposure and risk of climate impacts across the ecosystem variables. Specifically, shallow areas were projected to be simultaneously exposed to more intense warming, reduced sea ice coverage, freshening, and acidification relative to the regional averages. In addition, for species occurring in the BS–AG, low adaptability and high sensitivity to climate hazards was identified. These applied tools and evaluations can inform marine spatial planning and climate adaptation efforts to help achieve conservation objectives and sustain ecosystem and community health in a changing Arctic climate.
Continue reading ‘Assessing vulnerability of Arctic fish species to climate change’Acidification, warming, and nutrient management are projected to cause reductions in shell and tissue weights of oysters in a coastal plain estuary
Published 16 July 2025 Science ClosedTags: biological response, communitymodeling, fisheries, modeling, mollusks, morphology, multiple factors, North Atlantic, nutrients, respiration, temperature
Coastal acidification, warming, and nutrient management actions all alter water quality conditions that marine species experience, with potential impacts to their physiological processes. Decreases in calcite saturation state (ΩCa) and food availability, combined with warming water temperatures, pose a threat to calcifying organisms; however, the magnitude of future changes in estuarine systems is challenging to predict and is not well known. This study aims to determine how and where oysters will be affected by future acidification, warming, and nutrient reductions, and the relative effects of these stressors. To address these goals, an oyster growth model for Eastern oysters (Crassostrea virginica) was embedded in a 3-D coupled hydrodynamic-biogeochemistry model implemented for two tributaries in the lower Chesapeake Bay. Model simulations were forced with projected future conditions (mid-21st century atmospheric CO2 and atmospheric temperature under Representative Concentration Pathway (RCP) 8.5, as well as managed nutrient reductions) and compared with a realistic present-day reference run. Together, all three stressors are projected to reduce ΩCa and growth of oyster shell and tissue. Increased atmospheric CO2 is projected to cause widespread reductions in ΩCa. The resulting reductions in oyster shell and tissue growth will be most severe along the tributary shoals. Future warming during peak oyster growing seasons is projected to have the strongest negative influence on tissue and shell growth, due to summer water temperatures reducing filtration rates, enhancing shell dissolution and oyster respiration rates, and increasing organic matter remineralization rates, thus reducing food availability. Nutrient reductions will exacerbate deficits in oyster food availability, contributing to further reductions in growth. Quantifying the effects of these stressors provides insight on the areas in the lower bay where oysters will be most vulnerable to mid 21st-century conditions.
Continue reading ‘Acidification, warming, and nutrient management are projected to cause reductions in shell and tissue weights of oysters in a coastal plain estuary’A new model predicts dynamic seawater chemistry on Florida’s coral reefs
Published 1 July 2025 Press releases ClosedTags: communitymodeling, modeling
Water masses move over reefs, seagrass beds, and sandbanks – and as they do, the seawater chemistry changes.
In the Florida Keys, changes in coral reef carbonate chemistry are driven by benthic metabolism, the origin of the water mass, and the connectivity of habitats. A new study from NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) shows how we can use existing monitoring data to better understand the combined influence of these factors on local reef water chemistry.
Dr. Heidi Hirsh, an Assistant Scientist with the AOML Coral Program, demonstrates how integrating the source water, or “endmember”, chemistry conditions, the benthic habitat, and the flow of water between habitats can be used to predict the nearshore carbonate chemistry on a specific coral reef.
Benthic communities (i.e. seagrass, coral), source water (“endmember”) chemistry and the complex flow of water (hydrodynamics) between habitats all influence the local carbonate chemistry of a coral reef. Derived from: Hirsh, et al., 2025
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As part of the four-year Florida Regional Ecosystems Stressors Collaborative Assessment (FRESCA), a collaboration co-led by NOAA’s Atlantic and Meteorological Laboratory (AOML) and the University of Miami, Hirsh has developed a statistical model to predict nearshore coral reef carbonate chemistry based on modeled trajectories of currents and the interconnection between relevant sourcewater and habitats.
This approach takes into account where the water came from and the influence of marine ecosystems (i.e. benthic community metabolism) on a water mass before it arrives on a reef in a specific area.
Continue reading ‘A new model predicts dynamic seawater chemistry on Florida’s coral reefs ‘Biophysical model of eelgrass and water quality in Coos Bay, OR shows greater mitigation potential for ocean acidification than hypoxia
Published 30 June 2025 Science ClosedTags: biological response, chemistry, communitymodeling, mitigation, modeling, North Pacific, phanerogams
Seagrass beds provide important ecosystem services and are valued, in part, for their potential to mediate stressors such as ocean acidification and hypoxia (OAH) for sensitive species. However, the susceptibility of seagrasses to anthropogenic impacts and recent declines motivate the need to better understand the drivers of seagrass and the water quality consequences that occur with variation in seagrass abundance. To meet this need, we leveraged existing monitoring data (water quality and seagrass), hydrodynamic circulation model, and biogeochemical model framework with seagrass submodel, to produce a biophysical model of Coos Bay estuary, Oregon, U.S. The model includes biogeochemical processes involving water quality, plankton, seagrass, and sediment-water interactions. Ecosystem models like this are useful for evaluating complex estuarine systems because they allow us to extend our understanding of system dynamics beyond existing observations and perform experiments to identify the processes driving observed patterns. We used the biophysical model of Coos Bay to evaluate the dynamics of water quality and native eelgrass (Zostera marina) under three eelgrass abundance scenarios (zero eelgrass, current extent, and maximum observed extent) to elucidate the relationship between eelgrass and OAH. Including eelgrass in the Coos Bay model produced results that more closely resembled water quality observations – dissolved oxygen (DO) and pH were more dynamic in simulations with eelgrass, often having both higher highs and lower lows. While there were some areas of the estuary where DO improved with the addition of eelgrass to the model there was overall a small net increase in harmful DO conditions (based on a salmon physiological threshold). In contrast, ocean acidification conditions, pH and calcium carbonate saturation state for aragonite (Ω), were improved (based on oyster requirements) with the addition of eelgrass – although the magnitude of improvement differed seasonally and spatially. Our new model represents a useful tool – one which accounts for and controls the relevant physical and biogeochemical processes – to evaluate conditions that confer resilience or enhance vulnerability to OAH in an important Pacific Northwest coastal estuary and results can inform the OAH-related dynamics occurring in other eastern boundary current estuaries.
Continue reading ‘Biophysical model of eelgrass and water quality in Coos Bay, OR shows greater mitigation potential for ocean acidification than hypoxia’Long-term successional dynamics and response strategies of harmful algal blooms to environmental changes in Tolo Harbour
Published 18 April 2025 Science ClosedTags: biogeochemistry, biological response, BRcommunity, chemistry, community composition, communitymodeling, field, mitigation, modeling, North Pacific, otherprocess, physiology, phytoplankton, policy
Highlights
- Long-term monitoring reveals significant shifts in harmful algal bloom species and toxin dynamics in Tolo Harbour.
- Government actions reduced nutrient levels, but climate change and organic nutrients influenced HABs’ species succession.
- Number of HABs decreased, meanwhile frequency and types of new toxin species emerged, highlighting complex ecological changes.
- Balanced dual nutrient reduction strategies are essential for controlling HABs and restoring coastal ecosystem health.
ABSTRACT
The production and succession of harmful algae blooms (HABs) are attributed more to excessive nutrient concentrations and unbalanced nutrient stoichiometry than to other environmental drivers as the absence of long-term monitoring data. This study analyzed HABs succession patterns and key drivers in Tolo Harbour from 1986 to 2023, leveraging nearly 40 years of data. Effective governmental measures significantly improved water quality, with dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), 5-day biochemical oxygen demand (BOD5), and Escherichia coli (E. coli) concentrations decreasing by 53%, 80%, 45%, and 59%, respectively. Annual HABs events dropped from 28 to 3, and species diversity declined from 6 to 2. However, toxic species frequency rose from 21% to 46%. Dinoflagellates emerged as dominant initial species, with a shift in secondary dominance from diatoms to ochrophytes and toxin types from diarrhetic shellfish poisoning (DSP) to hemolytic toxins (HT). These shifts likely result from combined human and natural influences. Model simulations confirmed that red tide outbreaks, species succession, and shifts in toxin types were driven by declining pH, rising temperatures, unbalanced nitrogen-phosphorus ratios, organic nutrient increases, and algal antagonism. The study emphasizes the importance of the dual reduction of both DIN and DIP, meanwhile inorganic and organic nutrients, suggesting that overly focusing on or distract from one nutrient (e.g., DIP or DON) could lead to unintended ecological consequences, like the proliferation of rare and toxic species. We highlight the combined impacts of climate change (warming and ocean acidification) and anthropogenic activities (nutrient pollution and eutrophication) on HABs, particularly the number and toxin production. This research links policy changes to HAB dynamics, offering strategic recommendations for managing red tides and contribute novel perspectives on the impact of nutrient reduction in comparable bay ecosystems.
Continue reading ‘Long-term successional dynamics and response strategies of harmful algal blooms to environmental changes in Tolo Harbour’Statistical prediction of in situ coral reef carbonate dynamics using endmember chemistry, hydrodynamic models, and benthic composition
Published 3 March 2025 Science ClosedTags: chemistry, communitymodeling, field, modeling, North Atlantic
In the face of rapidly compounding climate change impacts, including ocean acidification (OA), it is critical to understand present-day stress exposure and to anticipate the biogeochemical conditions experienced by vulnerable ecosystems like coral reefs. To meaningfully predict nearshore carbonate chemistry, we must account for the complexity of the local benthic community, as well as connectivity between habitats and relevant endmember carbonate chemistry. Here, we adopt a system-scale approach to predict site-scale effects of benthic metabolism on the carbonate system of the Florida Reef Tract (FRT). We utilize bimonthly carbonate chemistry data from ten cross-shelf transects spanning 250 km of the FRT to model changes in dissolved inorganic carbon (DIC) and total alkalinity (TA). Benthic habitat maps were used to broadly classify communities known to impact carbonate chemistry. A SLIM 2D hydrodynamic model with mesh resolution reaching 100 m over reefs and along the coastline was used to determine the relevant water mass histories and identify the upstream benthic communities shaping local carbonate chemistry. These historical metabolic footprints, or “flowsheds”, were used to build predictive models of the change in DIC and TA at each station. The best predictive models included the chemical impacts of benthic ecosystem metabolism, as defined by water mass trajectories, weighted endmember chemistry, volume, time, and other environmental parameters (light, temperature, salinity, chlorophyll-a, and nitrate). Considering water mass for 5 days prior to sample collection yielded the highest model skill.
Continue reading ‘Statistical prediction of in situ coral reef carbonate dynamics using endmember chemistry, hydrodynamic models, and benthic composition’An environmentally adaptive CRO-SL algorithm based on dynamic agents for the channel assignment problem in wireless networks
Published 15 January 2025 Science ClosedTags: biological response, BRcommunity, communitymodeling, corals, methods, modeling
In recent decades, metaheuristic algorithms have emerged as indispensable tools for addressing complex optimization challenges, particularly in several engineering fields, where NP-hard problems are prevalent. A common NP-hard problem in communication engineering is the Channel Assignment Problem (CAP) for wireless access points (APs), with a determined number of stations (STAs) connected to them. The performance of the complete network depends on the interference and noise among the different clusters of devices and the obstacles or elements placed in the physical transmission space. To address the CAP, a new environmentally adaptive approach is proposed for the Coral Reefs Optimization with Substrate Layers (CRO-SL) algorithm, introducing new environmental agents: algae (representing tabu positions) and ocean water acidification (lowering fitness thresholds). The Environmentally Adaptive CRO-SL (EnvAdapt-CRO-SL) implementation aims to improve solution exploration, enhancing computational efficacy in generating new candidate solutions within the coral reef population. An exhaustive comparative analysis of four configurations of the proposed EnvAdapt-CRO-SL variant assesses the impact of each environmental agent on the algorithm’s performance. Additionally, external benchmarks against four different metaheuristics, along with an analysis of the influence of pseudorandom number generators on initialization and search operators, and a robust optimization case study, provide deeper insights. The results show that incorporating the new environmental agents into the EnvAdapt-CRO-SL workflow significantly boosts throughput while reducing the computational time required to obtain optimal solutions.
Continue reading ‘An environmentally adaptive CRO-SL algorithm based on dynamic agents for the channel assignment problem in wireless networks’Projections of coral reef carbonate production from a global climate coral reef coupled model
Published 17 December 2024 Science ClosedTags: biological response, BRcommunity, calcification, communitymodeling, corals, modeling, multiple factors, temperature
Coral reefs are under threat due to climate change and ocean acidification. However, large uncertainties remain concerning future carbon dioxide emissions, climate change and the associated impacts on coral reefs. While most previous studies have used climate model outputs to compute future coral reef carbonate production, we use a coral reef carbonate production module embedded in a global carbon-climate model. This enables the simulation of the response of coral reefs to projected changes in physical and chemical conditions at finer temporal resolution. The use of a fast-intermediate complexity model also permits the simulation of a large range of possible futures by considering different greenhouse gas concentration scenarios (Shared Socioeconomic Pathways (SSPs)), different climate sensitivities (hence different levels of warming for a given level of acidification), as well as the possibility of corals adapting their thermal bleaching thresholds. We show that without thermal adaptation, global coral reef carbonate production decreases to less than 25% of historical values in most scenarios over the twenty-first century, with limited further declines between 2100 and 2300 irrespective of the climate sensitivity. With thermal adaptation, there is far greater scenario variability in projections of reef carbonate production. Under high-emission scenarios the rate of twenty-first century declines is attenuated, with some global carbonate production declines delayed until the twenty-second century. Under high-mitigation scenarios, however, global coral reef carbonate production can recover in the twenty-first and twenty-second century, and thereafter persists at 50-90% of historical values, provided that the climate sensitivity is moderate.
Continue reading ‘Projections of coral reef carbonate production from a global climate coral reef coupled model’Ecophenotypic variation in a cosmopolitan reef-building coral suggests reduced deep-sea reef growth under ocean change
Published 7 November 2024 Science ClosedTags: biological response, communitymodeling, corals, field, Mediterranean, modeling, morphology, North Atlantic, South Atlantic
Sensitivity of reef-building corals to environmental factors has far-reaching ecosystem implications, especially in the limited number of cold-water coral (CWC) species that form reefs in the deep sea. Understanding CWC responses to large-scale oceanographic variation in their natural habitat can elucidate their sensitivity to global anthropogenic stressors. Here, we use skeletal samples to analyse fine-scale phenotypic variation in the widespread reef-building CWC Desmophyllum pertusum (Lophelia pertusa) in relation to broad physicochemical gradients in different sites across the Atlantic Ocean and Mediterranean Sea. We find evidence, amidst local and regional differentiation, of species-wide growth responses to physicochemical factors, mainly affecting corallite length, width and their ratio (slenderness). Our results suggest that higher temperature and lower oxygen levels negatively affect skeletal linear extension and budding rate of polyps. As also hinted by the reduced corallite length and slenderness in less developed reefs, these widespread responses may lead to a general decline in CWC reef growth rates as a long-term consequence of ocean warming and deoxygenation. Given this relevance, such responses can be used to model reef growth in a changing ocean.
Continue reading ‘Ecophenotypic variation in a cosmopolitan reef-building coral suggests reduced deep-sea reef growth under ocean change’Anthropogenic climate change will likely outpace coral range expansion
Published 26 August 2024 Science ClosedTags: biological response, communitymodeling, corals, modeling, review
Past coral range expansions suggest that high-latitude environments may serve as refugia, potentially buffering tropical biodiversity loss due to climate change. We explore this possibility for corals globally, using a dynamical metacommunity model incorporating temperature, light intensity, pH, and four distinct, interacting coral assemblages. This model reasonably reproduces the observed distribution and recent decline of corals across the Indo-Pacific and Caribbean. Our simulations suggest that there is a mismatch between the timescales of coral reef decline and range expansion under future predicted climate change. Whereas the most severe declines in coral cover will likely occur within 60–80 years, significant tropical coral range expansion requires centuries. The absence of large-scale coral refugia in the face of rapid anthropogenic climate change emphasises the urgent need to reduce greenhouse gas emissions, and mitigate non-thermal stressors for corals, both in the tropics and high-latitudes.
Continue reading ‘Anthropogenic climate change will likely outpace coral range expansion’
