In this context, functional saturation is defined as the state in which a system’s capacity to sustain additional productive or regulatory functions becomes constrained due to cumulative anthropogenic pressures, even if some physical space remains available. This review examines whether the progressive contraction of terrestrial plant communities under intensifying anthropogenic pressure can be functionally compensated by the expansion of marine macroalgal systems in a high-CO2 world. Integrating perspectives from Earth system ecology, biogeochemistry, and spatial analysis, the study evaluates three interdependent dimensions: the saturation of habitable terrestrial space, the relative openness yet ecological constraint of marine environments, and the dynamic coupling between atmospheric CO2 and ocean chemistry. The synthesis reveals a fundamental asymmetry between land and ocean systems. Terrestrial ecosystems are undergoing direct structural transformation through land-use change, resulting in a measurable contraction of ecologically functional space and increasing transgression of planetary boundaries. In contrast, marine systems retain substantial geometric space but are subject to diffuse, cumulative stressors, particularly in productive coastal zones where macroalgal communities are most viable. Elevated CO2 exerts dual effects on marine primary producers, simultaneously enhancing photosynthetic potential while intensifying ocean acidification, with temporally lagged responses mediated by air–sea exchange dynamics. Although macroalgae may exhibit localized increases in productivity, their capacity to provide long-term carbon sequestration and ecosystem stability remains inherently limited due to rapid biomass turnover, susceptibility to regime shifts, and the interaction of multiple stressors. The available evidence suggests that marine macroalgal expansion is unlikely to fully compensate for terrestrial vegetation loss at global ecological and biogeochemical scales. Instead, the Earth system is undergoing a net reduction in biospheric resilience, characterized by declining terrestrial complexity and increasingly unstable marine productivity. These findings challenge assumptions of compensatory redistribution of primary production and underscore the necessity of preserving terrestrial ecosystems alongside mitigating pressures on marine environments.
Continue reading ‘Functional saturation of Earth’s habitable domains: constraints on land systems and potential in marine environments’Functional saturation of Earth’s habitable domains: constraints on land systems and potential in marine environments
Published 16 October 2026 Science Leave a CommentGravity-driven feeding currents in veliger larvae of the eastern oyster
Published 16 October 2026 Science Leave a CommentFeeding by marine invertebrate larvae depends critically on the low-Reynolds-number fluid mechanics of the feeding currents they generate. Yet the relative importance of gravity-driven versus drag-driven mechanisms in small invertebrate larvae has remained unresolved. Here, high-speed microscale imaging, micro-particle image velocimetry (μPIV), and an analytical axisymmetric Stokes-flow model are combined to quantify the feeding currents of free-swimming veliger larvae of the eastern oyster Crassostrea virginica. Despite their small body size (<330µm), the larvae possess a high excess density (∼181g/m3), shifting the force balance such that gravity-driven feeding currents dominate. μPIV measurements reveal flow fields with first-order (Stokeslet-type) spatial decay, yielding ecologically sufficient body-volume-specific maximal clearance rates of ∼2.5×106/day. These values agree with predictions from the Stokes-flow model, which decomposes the clearance into gravity-driven and drag-driven components and shows that the former consistently outweighs the latter across observed swimming speeds. The model further explains how slow swimming modulates clearance by ±44% relative to hovering. Together, these results demonstrate that C. virginica veligers operate in a gravity-dominated feeding regime similar to that of larger calanoid copepods, and that their feeding strategy is shaped by an interplay of excess weight, swimming kinematics, and ciliary propulsion. This work highlights the fundamental role of gravity in larval feeding mechanics and underscores the need to incorporate excess weight when evaluating form-and-function relationships in marine invertebrate larvae, particularly for shelled bivalve and gastropod larvae with high excess density.
Continue reading ‘Gravity-driven feeding currents in veliger larvae of the eastern oyster’High-speed imaging reveals how oyster larvae’s dense shell helps them feed—and may offer clues to why ocean acidification threatens their survival
Photos and video available for use with credits can be found here.
Woods Hole, Mass. (September 16, 2026) — Eastern oyster larvae are only 100–300 micrometers long, but their dense calcium carbonate shells make them substantially heavier than the surrounding seawater. A new study led by the Woods Hole Oceanographic Institution (WHOI) shows that this excess weight allows gravity to drive the feeding currents the larvae use to bring food to their mouths, a finding that reveals a critical role for gravity in how these tiny animals feed and survive.
The study, published in Physical Review Fluids, challenges the long-standing assumption that larvae this small rely primarily on the drag produced by swimming to generate the feeding currents that carry food toward their mouths. While it may be true in the case of many small plankton, oyster larvae prove to be an exception, placing them in the same gravity-dominated feeding regime as much larger copepods and revealing an unexpected role for their shells in helping them feed. The key difference is that drag depends primarily on the larva’s movement through the water, but gravity depends on the difference in density between the larva and the surrounding seawater.
“This tells us that the shell is doing more than just protecting the animal,” explained Houshuo Jiang, a senior scientist at WHOI and sole author of the study. “It is actually helping the larva feed. That means anything that changes the shell could also change how the larva gets its food.”
Jiang captured the larvae’s feeding behavior using a high-speed microscale imaging system (HSMIS) developed in his laboratory. Rather than observing larvae under a conventional microscope, the system uses long-working-distance optics and a high-speed camera to record animals swimming freely in a larger volume of seawater. He also added tiny tracer particles to the seawater and used a technique called micro-particle image velocimetry to track how those particles moved around the larvae, allowing him to measure the invisible currents generated as the larvae feed.
“Usually, when you use a microscope, you need a lot of light, and if you put a lot of light on these tiny animals, you can heat the water and change their behavior,” Jiang said. “And conventional cameras are not fast enough to capture these very rapid movements. So we developed a system that uses a low-heat red LED and a high-speed camera that can record 2,000 frames per second. That lets us watch the larva in a larger volume of water without disturbing it and actually see how the water moves as it feeds.”
These findings offer a possible explanation for results from earlier experiments that raised bivalve larvae in space. In a 1999 study, scientists raised bivalves in microgravity and found that larvae reared without normal gravity tended to have lower feeding and growth rates and were in poorer condition than larvae kept under normal gravity. At the time, the physical reason for those differences was not clear.
“Thanks to high-speed imaging, we now see that gravity is essential for their feeding,” Jiang said. “If a larva is dealing with a stressor that affects its ability to build a dense shell, that could also affect the physical force that helps it feed. Understanding that connection gives us a better way to think about how environmental stressors can affect larvae at one of the most vulnerable stages of their lives.”
Oysters are particularly vulnerable to ocean acidification, which changes seawater chemistry and makes it harder to build calcium carbonate shells. This study’s findings suggest that if acidification alters shell formation enough to reduce a larva’s density relative to seawater, it could also weaken the gravity-driven feeding current it relies on to bring food to its mouth, potentially affecting young oysters.
Eastern oysters also face other challenges including pollution, disease, and overfishing. According to NOAA Fisheries’ Commercial Fishing Landings database, the commercial harvest of eastern oysters in the United States fell by about $15.2 million, or 7.2%, from 2023 to 2024.
“Ultimately, this could help us better understand what determines whether oyster larvae survive and become part of the adult population,” Jiang said. “That matters for fisheries and aquaculture because the number of larvae that survive each year helps determine the oysters available to harvest in the future. If environmental stressors affect both shell formation and feeding, we need to understand those effects to better predict how oyster populations will respond to a changing ocean.”
Continue reading ‘Tiny oyster larvae rely on gravity to feed’Evaluating ocean acidification and hypoxia model outputs as an undergraduate intern at the Northeast Fisheries science center
Published 16 October 2026 Web sites and blogs Leave a CommentOcean acidification from an interns viewpoint.
My name is Ned Gable and I am currently an Environmental Science and Chemistry double major at the University of Mary Washington. I was born and raised in Richmond, Virginia.
I am a PADI Divemaster who is passionate about marine ecology and the biogeochemical components of the ocean. I plan to pursue a Ph.D. in chemical oceanography coming out of college.
Interning at the Northeast Fisheries Science Center as a Young Researcher
Receiving word that I had won the Hollings Scholarship in early spring 2025 was one of the most exhilarating moments of my life. I was finally getting my shot at contributing to an organization that I admired, with nationwide impacts on science and our understanding of the natural world.
The workplace of my selected internship was at the Northeast Fisheries Science Center in Narragansett, Rhode Island. The building was smaller than I had expected, with only one floor, but there were a plethora of passionate scientists working there who made each day interesting and exciting. Right down the hall from my cubicle was the fish dissection lab, where they would dissect mackerel and squid for gonads and otolith research.
My project involved compiling large amounts of observational data across time in the Northeast U.S. Shelf and comparing it to model outputs (MOM6-COBALT) of acidification and hypoxia. The complicated part was figuring out exactly how to compare raw observational data from specific times and coordinates to a gridded model output. While it took a few weeks of research and testing, I came up with a method to match observational data to model grids, average that data within each grid by day, and then compare the model outputs within ±1 day and ±1 grid to each averaged observation using Python code.
When I finally achieved this, I was able to locate exactly where hypoxia or acidification was occurring and if the model was capable of detecting these events. Seeing the outputs of my research was one of the most gratifying accomplishments not only of this internship but throughout my educational career.
I had three wonderful and intelligent mentors at the center who guided my learning and helped me direct my ideas into project outputs. My primary mentor, Dr. Joseph Caracappa, works as a Northeast region modeler focused on integrating environmental models and information into fisheries management efforts. Dr. Kimberly Hyde, a brilliant researcher working on remote sensing of phytoplankton blooms, was my co-mentor and primary mentor to my fellow intern, Grace Davis. She would come in every morning to make sure we were on track and not too confused by the code. Haley Synan, a graduate student at the University of Rhode Island Graduate School of Oceanography, would answer any questions we had about coding and provided a very useful handbook for applying our coding skills.
Dr. Caracappa’s approach to mentorship was one that allowed me to come up with my own solutions to research questions and problems. Thanks to this, I have flourished as a researcher and developed new skills that I had never before considered using in my career.
A great and fun aspect about being a research intern was the field trips we got to take. While in Rhode Island, we toured the R/V Pisces, a 208-foot ship with extensive research capabilities. A large amount of the data I used to validate ocean acidification and hypoxia model outputs came from this very vessel.
We also toured the Milford Laboratory and saw oyster farming research, the local fish processing factories, the Woods Hole Oceanographic Institution, and University of Rhode Island-Graduate School of Oceanography, giving us a lot of networking experience while also having fun.
Overall, this experience was transformative for me as a researcher as I gained computer-based skills. This opportunity has opened doors for me and my career, and I am eternally grateful to the Hollings program and my wonderful mentors who made me feel welcomed at the Northeast Fisheries Science Center.
Reducing nitrate loads to the St. Lawrence river could mitigate hypoxia and acidification in its deep estuary and gulf
Published 15 October 2026 Science Leave a CommentHypoxia in marine systems is expanding worldwide due to anthropogenic activities. Deep waters of the St. Lawrence Estuary and Gulf are rapidly deoxygenating (∼1 mmol O2 m−3 y−1), driven by changes in Atlantic water-mass intrusion and nutrient‐fueled remineralization, and are simultaneously acidifying (∼0.004 pH unit y−1). These changes alter biogeochemical cycles and degrade habitats, causing biotic and economic consequences. Using a coupled physical-biogeochemical model, we tested whether watershed-scale nitrate reductions could mitigate deep‐water deoxygenation and carbonate-system degradation. Three nitrate‐reduction scenarios reduced riverine St. Lawrence River nitrate loads by about 11%, 30%, and 50% (−2.8, −7.5, and −11.7 mmol N m−3, respectively). Relative to the baseline simulation, these scenarios increased dissolved oxygen concentrations (DO) (+1.6, +4.3, and +6.7 mmol O2 m−3), pH (+0.004, +0.010, and +0.016), and aragonite saturation state (Ωarag) (+0.003, +0.009, and +0.015) in the deep Laurentian Channel (⩾175 m). The volume of deep waters with DO saturation <30% decreased by 3%, 8%, and 13% (−27, −75, −122 km3), while volumes with pH <7.65 declined by 1.0%, 2.8%, and 4.5% (−22, −60, −96 km3). Severely corrosive waters (Ωarag <0.6) dropped by 1.4%, 3.7%, and 5.9% (−26, −71, −112 km3). Over 2014–2024, modelled improvements exceeded small interannual variability but remained within seasonal amplitudes of deep DO concentrations (∼11 mmol O2 m−3) and pH (∼0.015 units), nevertheless pointing to a detectable management signal. Although nutrient‐driven improvements remained smaller than climate‐forced trends, modelled nitrate load reductions could offset ∼56% and 80% of recent observed oxygen and pH declines, respectively, while reducing hypoxic and acidified (pH and Ωarag) water volumes. These findings provide quantitative evidence that watershed‐scale nitrogen mitigation, through improved agricultural practices and wastewater nitrogen removal, which necessitates cooperation across jurisdictions, can alleviate hypoxia and acidification in deep coastal ecosystems, making nutrient management an essential complement to climate adaptation strategies.
Continue reading ‘Reducing nitrate loads to the St. Lawrence river could mitigate hypoxia and acidification in its deep estuary and gulf’Ocean warming could cut omega-3 levels in seafood, study finds
Published 15 October 2026 Press releases Leave a CommentGlobal analysis finds rising ocean temperatures could reduce omega-3 fatty acids across marine food webs, with implications for seafood nutrition.
Ocean warming could reduce levels of omega-3 fatty acids in fish and other marine organisms, potentially affecting the nutritional value of seafood, according to a global study.
Researchers analyzed 489 experiments from 143 published studies involving 132 marine species, including algae, invertebrates and fish. The study, published in Global Change Biology, examined how warming and ocean acidification affect fatty acids throughout marine food webs. The researchers found that warming generally reduced omega-3 fatty acids, with larger declines occurring as temperatures increased.
“Our new study shows many fish and other seafood will become less rich in omega-3s over time, due to rising ocean temperatures as the climate changes,” the researchers wrote in an article for The Conversation. “In fact, we found omega-3 could drop by 50 percent under very high warming scenarios. This is very bad news for human health but also for the health of other animals in the food web.”
Marine algae produce EPA and DHA, two important omega-3 fatty acids, and sit at the base of marine food webs. Those nutrients move through the food chain as algae are eaten by other organisms, which in turn are consumed by fish and larger animals.
“If EPA and DHA levels get disrupted along the food chain, less of those crucial fatty acids are available for animals higher up – including humans,” the researchers wrote.
The effects varied among species and experiments, but the overall analysis found warming had a stronger effect on fatty acids than ocean acidification. “We found ocean acidification had less impact on fatty acids than warming, suggesting rising temperature is the dominant driver of this problem,” the researchers wrote.
The results should not be read as a prediction that omega-3 levels in seafood will fall by 50 percent across the board. The study combined results from controlled experiments, and responses varied among species and experimental conditions. The researchers called for more long-term studies under realistic environmental conditions to improve predictions of how climate change will affect the nutritional quality of marine organisms.
The findings could have implications for fisheries and aquaculture because omega-3 availability is important to both the nutritional value of seafood and the health of marine organisms. The study’s authors said anticipating climate-driven nutritional declines will be important for fisheries management, aquaculture and food security.
The researchers also pointed to better use of fish processing byproducts as one way to make more of existing sources of omega-3. With up to 80 percent of fish parts discarded during food processing, they suggested those parts could be used to produce omega-3-rich fish oil or as nutritional ingredients in aquaculture feed.
“Given the projected declines in nutrition into the future, these wasted fish parts could be better utilized,” the researchers said. “This might, for instance, include making fish oil products rich in omega-3 and other nutrients, or using these fish parts as nutritional aquaculture feed.
Continue reading ‘Ocean warming could cut omega-3 levels in seafood, study finds’Environmental regulation of interspecific interactions among macrobenthic seaweeds and its implications for community phase transition
Published 15 October 2026 Science Leave a CommentMacrobenthic seaweeds are key species in temperate and boreal nearshore rocky ecosystems, and their interspecific interactions profoundly affect the species composition, spatial distribution and dynamic succession of the community. This paper systematically reviews the mechanisms of interspecific competition and facilitative effects among macrobenthic seaweeds. We also examine their environmental regulation and impacts on community phase transitions. Competition mainly centers on three major resources: light, space and nutrients. It manifests as an asymmetric hierarchical structure, in which canopy-forming species exert a disproportionate repressive effect on lower algal layers through light competition. Facilitative effects are realized through several mechanisms. These include canopy shading to mitigate heat stress and water loss, physical structure building to create complex habitats, and nutrient retention with chemical microenvironment regulation. Moreover, the relative strengths of facilitation and competition shift systematically across environmental stress gradients. Multi-trophic level regulation further shapes community diversity maintenance mechanisms through the suppression of dominant species by vegetative predators and the cascading effect of top predators on vegetative predators. In the context of global change, physiological asymmetries driven by oceanic heat waves are tilting the competitive balance in favor of opportunistic turf algae. These algae form a lock-in state through the triple positive feedbacks: physical barriers, biogeochemical deterioration, and chemosensory exclusion. This significantly decreases the resilience of algal field recovery. Tropical coral-macroalgae phase transition is highly consistent with the degradation of temperate algal fields in terms of driving logic. They follow the law of coupling resource competition imbalance, downward regulatory relaxation, and positive feedback lock-up. This paper suggests several priorities for future research. Studies should focus on the nonlinear response of multifactor interaction, the quantitative correlation between key functional traits and community resilience, and the establishment of a cross-ecosystem comparison framework. These efforts will provide theoretical support for predicting and adaptively managing offshore ecosystems under global change.
Continue reading ‘Environmental regulation of interspecific interactions among macrobenthic seaweeds and its implications for community phase transition’Explorers climate module 6.3 lesson plan: the impacts of climate change on ocean animals & habitats
Published 14 October 2026 Courses and training , Educational Materials Leave a CommentAbstract
This project aims to ignite curiosity and develop environmental empathy, this lesson empowers students to become ocean advocates by exploring how climate change impacts marine species across global climate zones. By translating complex scientific phenomena—such as ocean acidification, Blue Carbon, and the Whale Carbon Pump—into creative drama and news broadcasts, students build critical scientific literacy, collaboration skills, and a proactive commitment to protecting our shared ocean planet.
Description
Children will understand how global warming and ocean acidification impact marine animals and their natural habitats. They will explore how marine ecosystems capture carbon (focusing on Blue Carbon and the Whale Carbon Pump). They will work collaboratively to communicate scientific concepts through a creative news broadcast or drama performance.
Continue reading ‘Explorers climate module 6.3 lesson plan: the impacts of climate change on ocean animals & habitats’Explorers climate module 6.5 lesson plan: ocean acidification & shells
Published 14 October 2026 Courses and training , Educational Materials Leave a CommentAbstract
This project aims to inspire curiosity and scientific inquiry, this hands-on lesson allows pupils to investigate the chemical impact of ocean acidification on marine life. By modeling how acidic environments dissolve calcium carbonate shells and eggshells, pupils analyse data, connect chemical reactions to atmospheric carbon dioxide emissions, and identify practical solutions to protect vulnerable marine ecosystems.
Description
The children will learn to explain the concept of ocean acidification and how excess atmospheric 〖”CO” 〗_2changes ocean chemistry, to describe the chemical reaction between acids and calcium carbonate shells (“Acid”+”Carbonate”→”Carbon Dioxide”+”Water”+”Salt” ), and to conduct a fair test, gather quantitative/qualitative data, and record daily scientific observations. They will connect experimental results to real-world threats facing shell-building marine organisms (e.g., Irish mussels, oysters, and cold-water corals).
Continue reading ‘Explorers climate module 6.5 lesson plan: ocean acidification & shells’Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective
Published 14 October 2026 Science Leave a CommentWater quality monitoring in estuarine ecosystems is essential for assessing the health and sustainability of these dynamic coastal habitats, which are increasingly vulnerable to environmental change and human impacts. This study aims to characterize long-term trends and seasonal drivers of seven key water quality parameters: temperature, salinity, dissolved oxygen (DO), pH, chlorophyll-a (Chla), nitrate + nitrite (NOx), and phosphate (PO4) across four southern U.S. National Estuarine Research Reserves (Apalachicola Bay, Grand Bay, Mission-Aransas, and Weeks Bay) to identify which reserves and processes are most vulnerable to climate and anthropogenic change. Using two decades of data (1995–2020) and applying Generalized Additive Models (GAMs), we identified significant spatial and temporal patterns linked to environmental and anthropogenic factors. Results revealed a warming trend in Weeks Bay (+0.1035 °C/year, P = 0.0013), a salinity decline in Grand Bay (−0.1699 PSU/year, P = 0.033), and a salinity increase in Apalachicola Bay (+0.2055 PSU/year, P = 0.003). DO concentrations peaked in spring and dropped in summer, reflecting seasonal nutrient inputs. Grand Bay exhibited the highest Chla variability (CV=131.48%). NOx concentrations declined in Grand Bay (−0.0003 mg/L/year, P = 0.0162), while PO4 levels remained relatively stable. pH trends suggested localized acidification, particularly in Mission-Aransas (−0.0071/year, P = 0.0016). GAM results emphasized the combined effects of long-term and seasonal changes, with site-specific differences. These findings provide critical insights into estuarine functioning and highlight the need for regionally tailored management strategies to enhance resilience and biodiversity conservation in U.S. coastal reserves.
Continue reading ‘Spatiotemporal water quality dynamics in Southern U.S. coastal reserves: a long-term perspective’Frameworks for ocean management in a changing climate
Published 13 October 2026 Events Leave a Comment
Date: Wednesday, 25 November 2026
Time: 19:00–20.00
Location: Statsraaden Bar & Reception
Free and open for all. No registration required.
What happens when oceans change faster than the frameworks designed to manage them? Climate change is altering marine ecosystems, moving fish stocks, and increasing uncertainty for decision-makers. In this event, two researchers will share their knowledge on how climate change has an impact on the legal governance and management of ocean resources.
About the event (held in English)
Climate change is increasingly challenging the management and legal governance of marine resources by altering ecosystems, species distributions, and the assumptions on which existing governance frameworks are built. The North Sea and the Barents Sea, both highly productive and intensively managed regions, illustrate these pressures clearly.
Warming waters, changing ocean circulation, ocean acidification, and declining sea ice are reshaping marine ecosystems. In the Norwegian Sea, key commercial species such as mackerel are shifting their distributions, In the Barents Sea, rapid warming and reduced ice cover allow boreal species to expand into traditionally Arctic areas, affecting species interactions in the ecosystem.
These changes create a growing mismatch between dynamic ecosystems, legal governance and fixed management boundaries. In the Norwegian Sea, complex international quota arrangements are strained as stocks move across national exclusive economic zones. In the Barents Sea, long-standing cooperative management faces new challenges as species distributions change and industrial activity increases.
Climate change also exposes the limits of single-species management. Altered growth rates, recruitment, and species interactions make it harder to rely on historical data, strengthening the case for ecosystem-based and precautionary approaches. Overall, climate change places pressure on marine legal governance to become more adaptive, flexible, and forward-looking, requiring stronger international cooperation, better integration of climate science, and management systems designed for continuous change rather than stable conditions.
In this event, two researchers will share their knowledge on how climate change has an impact on the legal governance and management of ocean resources.
Talks
- The Law of the Ocean: Governance, Justice, and Sustainability: by Rosa Manzo, postdoctoral fellow, Faculty of law, University of Bergen (UiB)
- Climate change and fisheries management with some examples from the Northeast Atlantic: by Bjarte Bogstad (external link), Researcher, Institute of marine research (IMR/HI)
The speakers
Rosa Manzo holds a PhD in climate change law and has extensive experience in environmental and climate law. She has worked on topics such as carbon storage, climate justice, and international agreements. She has strong knowledge of the CSR (Corporate Sustainability Reporting Directive), the CSDDD (Corporate Sustainability Due Diligence Directive), and the Carbon Border Adjustment Mechanism (CBAM).
Bjarte Bogstad (external link) has many years of experience in stock assessment and advisory work for fish stocks in the Barents Sea. He is stock coordinator for Northeast Arctic cod (cod in the Barents Sea), and has participated in the Norwegian–Russian Fisheries Commission since 2010. He has long-standing experience in collaboration with the Russian research institute PINRO in Murmansk, including responsibility for the joint database on fish stomach content, and is the Norwegian representative to ICES ACOM since 2019.
Organisers
Ocean Science Bar is a collaboration between Statsraad Lehmkuhl, the University of Bergen, the Institute of Marine Research, NORCE, and the Nansen Center. At the Statsraaden Bar & Reception you are welcome to enjoy highlights from marine research and ocean related issues in informal and relaxing surroundings.
Continue reading ‘Frameworks for ocean management in a changing climate’Bioturbation under stress: linking coastal environmental change to the physiology and function of marine bioturbators
Published 13 October 2026 Science Leave a CommentCoastal benthic habitats are increasingly exposed to human-driven environmental changes, resulting in multiple co-occurring stressors. Bioturbators, which provide vital ecosystem services, are particularly vulnerable due to their limited mobility and are directly exposed to these multiple stressors. However, the ecological impacts of these stressors on bioturbators, especially their activity levels, remain poorly understood. This review synthesizes current knowledge on how selected environmental stressors, including extreme weather events, eutrophication, and anthropogenic emissions, affect bioturbation, organismal physiology and survival. Reported impacts vary widely depending on the species and stressors’ intensity. The strongest negative effects were typically observed under high-intensity stressor scenarios, which sometimes exceeded environmentally relevant thresholds. However, only a few studies examined the combined effects of multiple stressors. Their effects on bioturbators can be neutral, antagonistic, synergistic or additive, highlighting the complexity of stressor interactions in natural systems. The summary of this review suggests that key ecosystem functions provided by bioturbators are threatened by constant exposure to multiple environmental stressors and that ongoing environmental changes are further exacerbating this situation. To better understand the risks faced by these organisms, it is important to explore the combined effects of multiple stressors, to support more accurate predictions and effective conservation and restoration efforts.
Continue reading ‘Bioturbation under stress: linking coastal environmental change to the physiology and function of marine bioturbators’Ocean warming and acidification alter larval development and swimming behavior in the Atlantic sea scallop, Placopecten magellanicus
Published 13 October 2026 Science Leave a CommentOcean warming (OW) and ocean acidification (OA) are expected to have wide-ranging consequences for populations in marine systems caused by organism-level responses at a range of life history stages, including early larval stages. The Atlantic sea scallop, Placopecten magellanicus, is an economically important bivalve species that may be vulnerable to ocean change, but larval responses remain unclear. While the effects of OW and OA are known to impact adult sea scallops, little is known about the interactive effects of these two factors on early life stages. Larval dispersal is key to population-level patterns (e.g. abundance and distribution), but is contingent on growth rates and vertical swimming behaviors, which are both influenced by environmental conditions. Here, we evaluate the combined effects of OW and OA on larval development and behavior in a factorial lab experiment. We maintained larval sea scallop cultures up to metamorphosis under a range of physico-chemical conditions (17℃ and 14℃, and pH 7.3, 7.6, 7.9). Sea scallop larval development time was temperature dependent (1 vs. 1.5 months). There was an interactive effect of OW and OA on growth, where OA limited gains in growth experienced in warmer conditions. OA limited a decline in distribution late in development, while OW dominated individual vertical swimming behavior in intermediate development. Finally, ΩAr growth sensitivity was intermediate compared to that of other bivalve taxa. These results contribute to an improved understanding of developmental and behavioral responses to OW and OA, and provide information necessary for improved larval dispersal models under ocean change.
Continue reading ‘Ocean warming and acidification alter larval development and swimming behavior in the Atlantic sea scallop, Placopecten magellanicus’Variability in nitrogen uptake rates related to anthropogenic nutrient sources and carbonate system dynamics in the tropical coastal ocean
Published 12 October 2026 Science Leave a CommentHighlights
- Elevated CO2 and diverse nitrogen inputs interactively modulate nitrogen uptake rates.
- Ammonium-induced suppression of nitrate and subsequent co-dominance maximize nitrogen uptake.
- Efficient biological pump as the regenerated and new production coexist.
- West coast of India serves as a model system for rapidly developing tropical basins.
Abstract
The interaction between CO2 enrichment and nitrogen uptake under anthropogenic nitrogen inputs in the tropical coastal seas remains poorly understood. In this experimental study, we investigate the effects of elevated CO2 and impacts of various nitrogen sources such as river runoff, submarine groundwater discharge, industrial effluents, and atmospheric deposition, adding on NH4+ and NO3−uptake in tropical coastal waters. Using microcosm experiments along the west coast of India, a representative model system for tropical coastal ecosystems experiencing rapid anthropogenic development, we show that CO2 enrichment enhances nitrogen uptake, under intense anthropogenic nutrient enrichment. Our observations revealed a distinct uptake pattern of initial preference for NH4+ actively suppressed NO3− assimilation, subsequently leading to the co-dominance of NO3− and NH4+ uptake rates. The correlation between regenerated and new production acts as an efficient coastal biological pump in the coastal waters. These findings suggest that rising anthropogenic CO2, alongside nutrient inputs, may intensify nitrogen cycling in tropical coastal oceans, with implications for primary production and ecosystem dynamics under changing environmental conditions.
Continue reading ‘Variability in nitrogen uptake rates related to anthropogenic nutrient sources and carbonate system dynamics in the tropical coastal ocean’VR scuba diving with harbor seals increases ocean connectedness, and the effect of conversational AI on pro-environmental engagement depends on prior experience with seals
Published 12 October 2026 Science Leave a CommentHighlights
- We tested OceanSpeak, a novel approach to marine environmental education that integrates an AI wildlife agent with VR.
- All participants experienced a significant increase in ocean connectedness and nature connectedness.
- Adjusting for covariates, AI-powered conversation with a virtual harbor seal led to greater empathy for seals.
- AI-powered conversation increased pro-environmental engagement among participants with prior experiences with seals.
- AI-powered conversation improved knowledge of seals for some participants but reduced knowledge of environmental actions.
Abstract
This study presents an empirical investigation of OceanSpeak—a unique combination of virtual reality (VR) scuba diving and conversational artificial intelligence (AI) designed to educate about how ocean acidification and overfishing impact marine life. This pre-registered study examined the effect of interacting with an AI-powered harbor seal on ocean connectedness, empathy with seals, pro-ocean behaviors, and knowledge. The participants were 106 adults affiliated with a university in California, the United States. Participants in the experimental group (N = 53) engaged with the complete version of OceanSpeak, including AI-powered conversation with a virtual harbor seal. We implemented a yoked control design such that participants in the control group (N = 53) were exposed to identical content but experienced another participant’s AI-enabled conversation. In addition, we measured a number of individual differences related to their views on the environment and specific experience with seals. All participants experienced a significant increase in ocean connectedness as a result of the intervention. The control condition outperformed the AI condition regarding knowledge of pro-environmental actions, whereas a small subset of AI participants demonstrated better understanding of seal-specific issues. Without accounting for individual differences, there were no significant differences between conditions in terms of ocean connectedness, empathy, and protective behaviors. However, post hoc analyses indicated that after accounting for baseline ocean connectedness and nature connectedness and their interactions with condition, AI-powered conversation led to significantly more empathy with seals. Moreover, AI-powered conversation with a virtual seal increased protective ocean behaviors among participants with prior seal exposure, suggesting previous experiences with the actor who is speaking in conversational AI may improve the outcome of those interactions.
Continue reading ‘VR scuba diving with harbor seals increases ocean connectedness, and the effect of conversational AI on pro-environmental engagement depends on prior experience with seals’Sinking feeling: testing for ocean health and carbon storage
Published 12 October 2026 Press releases Leave a CommentOur oceans are in trouble and new research from Flinders University shows how changes in diatoms (microalgae) could further undermine the foundation of aquatic life’s food webs – as well as vital deep-sea carbon capture or sequestration.
A new study published in Marine Ecology used high-tech methods to test common microalgal species to assess how various stressors, including acidification from excessive carbon dioxide (CO₂) levels, affect absorption of trace metals and therefore undermine their overall health and role in Earth’s carbon cycling.
Although microscopic, the single-celled algae diatoms that live in oceans, lakes, rivers and even damp soil are among the most important organisms on Earth as they produce a significant portion of oxygen in the atmosphere.
Diatoms account for 40%-50% of primary production in oceans, and they contribute to organic carbon being exported to the deep ocean by fixing CO₂ from near-surface waters, says senior author Professor Sophie Leterme, director of the ARC Industry Transformation Training Centre for Biofilm Research and Innovation at Flinders University’s College of Science and Engineering.
“We showed that changes in the ocean pH can affect the growth, abundance and elemental composition of these diatoms,” says Professor Leterme. “We need to investigate how these changes interplay between various trace elements and can lead to broader ecological impacts, such as disruption to marine food webs, reduced carbon and silicon export, and increased microbial and nutrient activity.”
Rising carbon emissions affect pH levels in seawater, which can alter planktonic algae’s absorption of trace elements including iron, zinc and cadmium, which are essential for inorganic carbon acquisition.
The dissolution of CO₂ into the ocean has already induced a global drop in pH of 0.1 units since the end of the Industrial Revolution, and values are expected to drop another 0.3–to-0.6 units by the end of this century.
Diatom species are great bio-indicators, often used to assess water quality and boost understanding of how ongoing ocean acidification and rising water temperatures downgrade their physiology and functioning – which have important consequences for the future of oceans.
The Flinders researchers say a better understanding how these complex processes work in seawater will help find solutions, including the development of novel biofilms to reduce shipping pollution in harbours.
Using seawater samples collected in South Australia’s Gulf St Vincent and from the CSIRO algae collection, the researchers’ highly sensitive neutron activation analysis was used in experimental setups on the species Thalassiosira pseudonana and Nitzschia navis-varingica.
The experiments, supported by ANSTO expertise, showed how trace metal uptake by marine diatoms could be applied to other marine organisms’ absorption to a wide range of a wide range of other elements in the environment.
“While a higher abundance and growth of diatoms might be beneficial to reduce carbon dioxide levels, the impact of lower concentrations of major and trace elements in the environment is not well understood.
The research article – ‘The impact of ocean acidification on the sorption of trace metals by diatoms’ (2026) by Sophie C Leterme, Tamar Jamieson, Alessandra Mazzoli, Angus Hambrook, Rachel S Popelka-Filcoff, John Bennett and Attila Stopic – has been published in Marine Ecology (Wiley). DOI: 10.1111/maec.70112.
Also see a new article published in the Australian Journal of Maritime and Ocean Affairs – ‘Australia’s changing oceans: Building knowledge for actionable outcomes’ DOI: 10.1080/18366503.2026.2710564.
Continue reading ‘Sinking feeling: testing for ocean health and carbon storage’Coupling and decoupling of DIC, TA and O2 benthic fluxes along the Rhône River-dominated ocean margin
Published 9 October 2026 Science Leave a CommentRiver-dominated ocean margins (RiOMar) and their benthic compartments play a key role in coastal carbon cycling due to the combined effect of high inputs of particulate organic carbon (POC), benthic mineralization and burial processes. This study quantified benthic fluxes of DIC, TA, and oxygen along a transect influenced by riverine POC inputs, providing new insights in diagenetic processes when switching from anaerobic to aerobic dominated sediment form the river mouth to the adjacent shelf. Fluxes at the sediment-water interface were measured ex-situ with sediment cores incubation during two cruises at the end of spring 2018 and 2022. Stations closest to the river mouth exhibit high benthic fluxes averaging 54 ± 20, 30 ± 21 and −27 ± 14 mmol m−2 d−1 for DICflux, TAflux and TOU, respectively, reflecting intense anaerobic remineralization and a strong decoupling between oxygen consumption and DIC production (DICflux:TOU ratio of 1.5 to 3.5). These large TA fluxes further support that FeS burial limits the reoxidation of reduced compounds in these sediments, allowing the upward diffusion of TA produced at depth towards bottom waters. Offshore, In contrast, shelf stations show lower flux intensities, 8 ± 3 mmol m−2 d−1 for DICflux, −1 ± 2 mmol m−2 d−1 for TAflux and −9 ± 2 mmol m−2 d−1 for TOU, suggesting a greater influence of aerobic mineralization, reoxidation processes and nitrification. Stations located in the Rhône prodelta show intermediate benthic fluxes of 24 ± 11, 6 ± 4 and −17 ± 7 mmol m−2 d−1 for DICflux, TAflux and TOU, respectively. By substantially expanding the spatial and temporal resolution of benthic DICflux, TAflux and TOU in this system, this study provides a robust quantitative framework for assessing the contribution of RiOMar sediments to coastal alkalinity budgets and emphasizes the important role of TA fluxes released from the sediment in increasing the buffering capacity bottom waters.
Continue reading ‘Coupling and decoupling of DIC, TA and O2 benthic fluxes along the Rhône River-dominated ocean margin’Differential gene expression reveals molecular mechanisms for physiological resilience to ocean acidification stress in native and introduced oyster species
Published 9 October 2026 Science Leave a CommentCoastal-estuarine habitats are rapidly changing with respect to ocean acidification (OA). Along the West Coast of the United States, coastal upwelling regions are high in productivity and rich in nutrients, making them key areas for aquaculture oyster production. The native Olympia oyster Ostrea lurida has experienced population collapse due increased commercial harvest, habitat loss, and the introduction of the non-native Pacific oyster Magallana gigas. Despite intense focus on physiological responses of oysters to OA stress, molecular underpinnings of have yet to be fully described, particularly in niche species. Juvenile oysters of both M. gigas and O. lurida were exposed to a range of experimental OA conditions for six weeks to investigate transcriptomic and biomineralization responses under fluctuating and chronic low pH. Low pH had a significant effect on shell dissolution for both Pacific and Olympia oysters, with no statistical difference observed between the two species. Differential gene expression revealed distinct differences in responses of the Pacific and Olympia oysters to OA on the transcriptomic level, with M. gigas showing elevated molecular responses to OA stress. Our findings suggest that the two species may employ distinct adaptive strategies to mitigate low pH that are informative for species-specific management strategies.
Continue reading ‘Differential gene expression reveals molecular mechanisms for physiological resilience to ocean acidification stress in native and introduced oyster species’Microplastics in a warming ocean with coupled climate change interactions and implications for marine ecosystem functioning
Published 9 October 2026 Science Leave a CommentHighlights
- Climate driven processes intensify microplastic fragmentation and redistribution.
- Microplastics disrupt carbon cycling and climate sensitive ocean processes.
- Warming acidification and ice melt amplify microplastic impacts on marine biota.
- Polar ice acts as a major reservoir and emerging source of legacy microplastics.
- Integrating microplastics into climate policy is critical for ocean resilience.
Abstract
Microplastics (MPs) pollution and climate change are now recognized as two pervasive and interacting stressors reshaping marine ecosystems, yet their combined effects remain insufficiently integrated within marine pollution research. This review synthesizes current global evidence on how climate-driven processes modulate the sources, transport, fate, and ecological impacts of MPs, and how MPs in turn influence climate-linked ocean processes. A systematic literature review was conducted following PRISMA principles, drawing on peer-reviewed studies retrieved from major scientific databases without temporal restriction. A total of 205 publications included for qualitative synthesis. The results demonstrate that ocean warming, acidification, sea-ice melt, extreme weather events, and altered circulation patterns intensify MP fragmentation, redistribution, and bioavailability across marine environments. Warming accelerates polymer degradation and enhances biological interactions, acidification alters surface chemistry and toxicity, and polar ice melt releases large reservoirs of legacy MPs into vulnerable ecosystems. Evidence further shows that MPs disrupt key climate-related processes, including primary productivity, nutrient cycling, and the biological carbon pump, thereby creating feedbacks that may weaken oceanic climate regulation. Combined exposure to MPs and climate stressors amplifies physiological stress, reduces growth and reproductive performance, and compromises resilience across multiple trophic levels. These findings highlight that MPs are not passive contaminants but active modifiers of climate-sensitive marine systems. Integrating MP dynamics into climate research, monitoring frameworks, and policy instruments is therefore essential. Addressing plastic pollution alongside climate mitigation and adaptation strategies will be critical to safeguarding marine ecosystem functioning under future global change.
Continue reading ‘Microplastics in a warming ocean with coupled climate change interactions and implications for marine ecosystem functioning’Behavioural responses of fishes to abiotic stressors: a comparative synthesis of shared physiological mechanisms and ecological consequences
Published 8 October 2026 Science Leave a CommentHighlights
- Comparative review of behavioural responses to major abiotic stressors
- Conserved physiological mechanisms underlie diverse behavioural responses
- Cross-stressor synthesis identifies common and stressor-specific effects
- Ecological consequences extend from individuals to populations
- Research priorities for predicting fish responses to global environmental change
Abstract
Anthropogenic activities, including global warming, deforestation, urbanization, intensive agriculture, and aquaculture, are accelerating environmental change with consequences for aquatic ecosystems. As ectothermic vertebrates, fishes are sensitive to alterations in abiotic conditions, responding through behavioural changes that influence survival, reproduction, and species interactions. Although several studies have investigated the effects of abiotic stressors, comparative syntheses across stressors remain limited, constraining our understanding of how environmental drivers influence fish behaviour. In this review, we synthesize evidence on the impacts of six abiotic stressors, including temperature, hypoxia, acidification, turbidity, salinity, and ammonia, and examine the processes underlying responses. Across these stressors, behavioural alterations affect swimming performance, feeding, predator avoidance, social interactions, habitat selection, exploration, courtship, and anxiety-like behaviours. Despite differences in their primary modes of action, these stressors frequently converge on physiological disturbances involving oxidative stress, neurotransmitter regulation, sensory impairment, ion homeostasis, and energy metabolism, ultimately producing behavioural outcomes with ecological consequences. Most studies have been conducted under controlled laboratory settings, limiting ecological relevance. Furthermore, the combined effects of multiple abiotic stressors, together with long-term, multigenerational, and transgenerational responses, remain poorly understood despite their potential consequences for fish growth, reproduction, recruitment, and community structure. This review highlights the urgent need for integrative, multi-stressor, and multigenerational studies spanning diverse species, developmental stages, and ecosystems to improve predictions of fish responses under environmental change. By identifying shared and stressor-specific responses, this synthesis provides a conceptual framework for understanding how abiotic stressors affect fish through physiological pathways that ultimately converge on common behavioural outcomes with important ecological implications.
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