A screening approach for aquaculture breeders based on sperm performance under climate change-related stress

Published 4 June 2026 Science Leave a Comment
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Highlights

  • Temperature rise reduced European sea bass and Senegalese sole sperm motility.
  • Gilthead seabream sperm showed lower variation under acidification and warming.
  • Challenge tests allowed differentiation among males based on sperm performance.
  • Approach provides a screening framework for sperm performance.

Abstract

We aimed to develop a screening approach to differentiate among males of European sea bass (Dicentrarchus labrax), gilthead seabream (Sparus aurata), and Senegalese sole (Solea senegalensis) based on sperm performance under environmental acidification and temperature increase. Sperm samples were selected using a CASA system, and three challenge tests were applied. The first one consisted of sperm activation with artificial seawater (ASW) across a pH range (7.6–8.2). The second assessed activation at species-specific temperatures. The third test evaluated the combined effect of ASW pH (7.8 and 8.2) and different temperatures. Results from the third challenge test revealed differences in sperm performance under environmental variations, allowing differentiation among males. For this purpose, sperm motility values obtained for each sample under species-specific natural environmental conditions were used as references, and variations in motility were compared across challenge conditions. Different levels in the criteria (regarding the different percentages of motility variation) were applied to differentiate among males. The temperature increase affected the sperm kinetic parameters of European sea bass and Senegalese sole, while gilthead seabream sperm showed lower variation under seawater acidification and rising temperatures. The challenge test allowed differentiation among males based on sperm performance under environmental variations and represents a preliminary screening approach. However, these results are based on in vitro conditions and should be interpreted as a first proxy, requiring further validation to establish links with reproductive performance in vivo.

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Pioneering research sheds new light on what shaped extinction pattern of prehistoric marine life – and size clearly mattered

Published 4 June 2026 Press releases Leave a Comment

Scientists have shown conclusively for the first time that tiny marine organisms in polar oceans survived the mass extinction event that wiped out prehistoric dinosaurs because they needed less energy and were more tolerant to darkness.

The study, led by the University of Bristol and published in the journal Nature, sought to solve a longstanding evolutionary enigma: what factors determined whether marine species would survive a mass extinction event known as the Cretaceous-Paleogene (K-Pg) boundary some 66 million years ago? Findings revealed that being small and accustomed to darkness proved to be the vital attributes.

Image shows microscopic marine plankton, which are larger in size and went extinct. Credit: Brian Huber Smithsonian

Study lead author Dr Rui Ying said: “It’s an exciting breakthrough. For so many years scientists have been unable to test what actually decided whether a species prevailed or perished because the extinction event involves multiple environmental changes like ocean acidification and darkness.”

“It is difficult to understand the causality because of the lack of fossil data and environmental proxy data, especially at century timescale. Using a numerical model, I looked at the base of the food chain – plankton – which helped us to identify the most likely cause and the best survival strategies for plankton.”

The Cretaceous–Paleogene (K–Pg) boundary is an ancient and much-studied geological signature marking the mass extinction that wiped out non-avian dinosaurs, separating the Mesozoic Era (the age of reptiles) from the Cenozoic Era (the age of mammals). It is thought that the impact of an asteroid, called Chicxulub, caused the extinction of around 75% of species in the fossil record by triggering catastrophic environmental changes.

Despite decades of research, the mechanisms linking the environmental changes to the selective extinction patterns observed in the fossil record have until now been unresolved. But by creating and deploying a unique model which maps ecosystem traits globally, the scientists have been able to establish what attributes resulted in the marine plankton community’s survival.

Dr Ying, who is now a Senior Research Associate at the University of East Anglia, said: “The model is based on trades and the trade-off of how often they are eaten by predators and what they can eat against specific attributes, such as temperature, light level and body size.”

Study co-author Dr Fanny Monteiro, Associate Professor in Ocean Sciences at the University of Bristol, explained: “The body size and abundance of small plankton mean the organisms rely on less energy, increasing their likelihood of survival. An ability to deal with lower light and darkness and turbulent waters in higher latitudes also makes them more adaptable to polar regions. In contrast, species adapted to higher light and warmer waters were more vulnerable to this type of mass extinction.”

The model allowed the traits of millions of organisms to be analysed and quantified with unprecedented accuracy, providing important insights into the physical and chemical changes linked to diversity. Besides shining a light on the distant past of marine life, the research can also help inform forecasts of how ecosystems might respond in future.

Study co-author Professor Daniela Schmidt, Professor of Earth Sciences at the University of Bristol, said: “This study not only demonstrates how trait-based models can help us better understand biodiversity crises in ancient history, but it also has potential to indicate how less light and hotter environments, as a result of global warming, might impact current and future ecosystems.”

The research was funded by China Scholarship Council (CSC)-Bristol PhD Scholarship and NERC grants.

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Environmental, phylogenetic, and palaeogeographic impact on relative septal thickness in Devonian ammonoids from Morocco

Published 3 June 2026 Science Leave a Comment
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Building upon previous research, this study examines potential relationships between septal thickness in Devonian ammonoids from the Anti-Atlas of Morocco and isotopic proxy data from the literature for atmospheric CO2, sea surface temperature, oceanic pH, and weathering (δ18O, δ13C, δ11B, 87Sr/86Sr). Recent studies have demonstrated that various mollusc groups show some growth sensitive to environmental factors. Our results indicate no significant correlation between septal thickness and the examined proxies, except for significantly thinner septa in the genus Phoenixites following the environmental perturbations during the Kellwasser Event, which included anoxic conditions and possibly ocean acidification. This supports the hypothesis that a positive selection for reduced shell material occurred in response to changing seawater chemistry. Additionally, our results align with published data and may support a correlation between septal thickness and palaeolatitude. This study contributes to our understanding of the evolutionary impacts of environmental stressors such as ocean acidification on ammonoids and their adaptive strategies to changing environmental conditions.

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Seasonal upwelling shapes coral reef community structure and photophysiology on the Pacific Coast of Costa Rica

Published 3 June 2026 Science Leave a Comment
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Reef-building corals form the calcium-carbonate frameworks that underpin tropical coral reefs, yet global coral cover has declined by ~50% in recent decades, due to marine heatwaves and other stressors. Identifying refugia environments, such as upwelling systems, that buffer stress, promote recovery, and enhance resilience by promoting physiological plasticity that supports thermotolerance is therefore critical. Here, we compared benthic community composition, coral percent cover, and photo-physiology between an upwelling location in the Gulf of Papagayo and a non-upwelling location in Sámara on the Pacific coast of Costa Rica. Waters in Papagayo were cooler, more acidic, and richer in chlorophyll a. Reefs at this location exhibited higher crustose coralline algae, higher sea urchin cover, and lower macroalgae cover, compared to Sámara. Papagayo also showed higher stony coral cover, driven by Pocillopora spp., while Sámara was dominated by massive, heat-tolerant Porites spp.. When significant, photophysiological measurements showed 9.7 – 44.5% higher photosynthetic efficiency (Fv’/Fm’) in Papagayo corals and 19.94 – 42.75 % higher maximum photosynthetic rates (Pmax) in Sámara corals. These results highlight how contrasting environmental regimes within a relatively small geographic area can shape distinct coral community compositions and photophysiological strategies, with implications for identifying areas of reef persistence or refugia.

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OA-ICC bibliographic database updated

Published 2 June 2026 Science Leave a Comment

An updated version of the OA-ICC bibliographic database is available online.

The database currently contains 9,859 references and includes citations, abstracts and assigned keywords. Updates are made every month.

The database is available as a group on Zotero. Subscribe online or, for a better user experience, download the Zotero desktop application and sync with the group OA-ICC in Zotero. Please see the “User instructions” for further details.

OA-ICC, 2 June 2026.

Upper-ocean variability of the marine carbonate system in the Northeast Pacific

Published 2 June 2026 Science Leave a Comment
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In the Northeast Pacific, the marine carbonate system’s variability across timescales is not well constrained. Here, we quantify observed seasonal and non-seasonal variability in Dissolved Inorganic Carbon (DIC), partial pressure of carbon dioxide () and aragonite saturation state  and discuss potential drivers. We used three decades of observations from four Line P time series stations, the longest marine carbonate system time series in the Northeast Pacific (1990–2019). To gauge the spatial extent of the variability patterns, we used output from a global ocean model representing the observed period. In the Northeast Pacific, seasonal and non-seasonal  variability at 10 m was minimal, mostly damped by the opposing influence of DIC and temperature changes at both seasonal and interannual timescales. For DIC and , the seasonal cycle dominated total variability in the top 60–70 m, with mean-transect 10 m seasonal amplitudes of 35  3 μmol  and 0.31  0.04, respectively. In the upper 60–70 m, the magnitude of non-seasonal variability was at least half that of the seasonal variability for most variables. From five climate indices examined, we focused on the basin-scale Pacific Decadal Oscillation index (PDO) to investigate potential drivers of non-seasonal variability, with 20%–40% of the non-seasonal variability in DIC and  associated to this index. In the Northeast Pacific, positive PDO periods were linked to a mean reduction in 10 m DIC of 5 μmol  and an increase in 10 m  of 0.04 for each PDO unit increase, which could potentially reduce the occurrence and severity of ocean acidification events. The opposite could be expected during negative PDO periods.

Plain Language Summary

Using 30 years of observations from the Northeast Pacific, we characterized sources of variability for three marine carbonate system variables: , dissolved inorganic carbon (DIC) and the saturation state of aragonite (an common indicator of ocean acidification). The  seasonal and non-seasonal variability was minimal in the top 10 m. The seasonal cycle of DIC and aragonite saturation state was the major contributor to total variability in the top 60–70 m, and not detectable below. Also, in the top 70 m of the water column, up to 20%–40% of the DIC and aragonite saturation state non-seasonal variability was associated to the Pacific Decadal Oscillation index (PDO). The PDO is a statistics-derived index that captures variability patterns influencing the whole Pacific basin and has a positive and negative phase. We found that a warmer than usual upper water column in the Northeast Pacific during a positive PDO phase, potentially driven by reduced mixing, was linked to a lower DIC and higher values of aragonite saturation state. The opposite could be expected during negative PDO periods. Knowing the magnitude of natural variability in the marine carbonate system is important to identify the emergence of ocean acidification and other human-driven changes in the ocean.

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Navigating the souring seas: the global experimentalist governance of ocean acidification

Published 2 June 2026 Science Leave a Comment
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Navigating the Souring Seas explores how ocean acidification (OA)-a significant yet under-governed environmental threat-is being addressed on the global stage. Bridging science, law, and international policy, this interdisciplinary book introduces global experimentalist governance as an innovative and adaptable framework for tackling complex and uncertain issues like OA. It provides a clear overview of the scientific background of OA and maps the international governance landscape, identifying it as a regime complex. Through detailed interview-based case studies of the Ocean Acidification Alliance and the International Maritime Organization, the book evaluates real-world efforts to govern OA and highlights how experimentalist features, such as flexibility, learning, and multilevel collaboration, can enhance their effectiveness. Accessible and timely, this book is essential reading for scholars, students, policymakers, and environmental practitioners seeking practical, forward-looking governance strategies for ocean and climate challenges. It offers both theoretical insight and concrete recommendations for improving global environmental governance.

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Hydrodynamic control of coral metabolism: a coupled modeling approach linking flow, physiology, and reef-scale biogeochemistry

Published 2 June 2026 Science Leave a Comment
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Tropical coral reefs exhibit high variability in coral metabolism, driven by complex interactions among physical, chemical, and biological processes. Understanding the spatiotemporal patterns of coral metabolism and their drivers is critical, as such variability may underpin corals’ adaptive capacity to withstand a warming and acidifying ocean. Here, we use a coupled hydrodynamic–biogeochemical–physiological model to investigate spatial and diel variations in coral metabolic processes (photosynthesis, respiration, and calcification) across Moorea’s north shore reef system under three prevailing wave regimes. We find that photosynthesis varies little across the reef, whereas respiration and calcification show pronounced spatial heterogeneity. These spatial patterns closely mirror the ones in seawater carbonate chemistry and depend strongly on wave-driven flow. Hydrodynamics regulate diffusive exchanges between coral tissues and surrounding seawater, and eventually generate distinct internal chemical environments (in the coelenteron and calcifying fluid) across the reef. Landward reef regions exhibit the greatest spatial and diel variability in coral metabolism. Low-wave, slow-flow conditions amplify metabolic fluctuations throughout the reef, but more strongly in the landward regions. Overall, our results highlight how interactions among transport processes, carbonate chemistry, and coral physiology produce strong day-night fluctuations and spatially heterogeneous but structured metabolic patterns across the reef, which vary systematically with wave conditions.

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From carbonate chemistry to community responses: thematic evolution in ocean acidification and microbial research — a bibliometric analysis

Published 1 June 2026 Science Leave a Comment
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Ocean acidification (OA) is reshaping marine biogeochemistry and threatens microbial communities that regulate carbon and nutrient cycling. Although existing bibliometric reviews have examined OA in relation to coral reefs, calcifying organisms, and broader marine ecosystems, no study has systematically mapped the specific sub-domain of OA impacts on microbial ecology, a gap that hinders identification of methodological blind spots, collaboration imbalances, and under-explored research frontiers unique to microbial systems. Meanwhile, research progress on OA-driven microbial change remains fragmented and lacks a systematic analysis of the field’s evolutionary trajectory and emerging frontiers. This study presents a comprehensive bibliometric analysis of 495 publications retrieved from the Web of Science Core Collection (2005–2025), utilizing CiteSpace to map the knowledge domain of OA impacts on microbial ecology. Temporal analysis reveals three distinct developmental phases: emergence (2005–2010), exponential growth (2011–2021), and recent stabilization (2022–2025). The global collaboration network spans 53 countries, characterized by a triadic leadership structure involving China, the United States, and Germany, with the GEOMAR Helmholtz Centre serving as a central institutional hub. Keyword co-occurrence and burst detection analyses uncover a significant paradigm shift: the research focus has transitioned from foundational carbonate chemistry parameters to complex ecosystem-relevant microbial processes, including community structure, functional genes, and biogeochemical cycling. Notably, “responses” emerges as the most active contemporary research frontier with the strongest recent citation burst, reflecting a consolidated focus on how microbial communities adapt to acidification stress at physiological, community-structural, and functional levels. However, network analysis also reveals structural blind spots: archaea and viral ecology remain conspicuously absent from high-frequency keyword clusters despite their recognized ecological importance, and research contributions from Africa, Southeast Asia, and Small Island Developing States are markedly limited. Based on these findings, we propose four evidence-linked strategic directions centered on multi-omics integration, spatiotemporal expansion through global observatory networks, factorial multi-stressor experimental designs, and bridging molecular processes to ecosystem-scale biogeochemical cycles. This study provides a data-driven roadmap for next-generation research on OA-microbe interactions, essential for predicting ecosystem resilience in a changing ocean.

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Chemical cues and molecular mechanisms suspected in abiotic stress communication

Published 1 June 2026 Science Leave a Comment
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For nearly a century, scientists have tried to resolve the sensory physiology of chemical communication caused by predation stress. Only recently have we evidenced that abiotic stressors from a changing world, such as heat and ocean acidification, also trigger chemical communication between aquatic organisms – which we dubbed abiotic stress communication. Generally, the behavioural and physiological response to stress-induced cues are well understood, whereas the molecular mechanisms – cue identities, pathways of release, and perception – of this stress communication remain unresolved. Here, we propose a framework to organize the existing evidence for candidate mechanisms involved in abiotic stress-induced chemical communication, focusing on heat and acidification as two major abiotic stressors with environmental relevance. Drawing on transcriptomic, metabolomic and behavioural evidence, we propose that stressor-specific communication likely involves multiple cues and parallel routes rather than a single mechanism, such as membrane-related processes. We call for integrative work that links -omics with chemical profiling and ecological function assays to uncover the mechanisms of abiotic stress communication.

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Tropical cyclones may soon flip from releasing carbon to absorbing it

Published 29 May 2026 Press releases Leave a Comment

For years, scientists have known that the ocean does a huge amount of the planet’s climate work for us.

The ocean absorbs a large share of the carbon dioxide, taking in roughly 20 to 30 percent of human-caused CO2 emissions since the industrial era. At the same time, tropical cyclones are among the most violent things that happen on Earth’s surface. They churn the upper ocean, stir up deep water, cool the sea surface, and leave behind lingering physical changes that can last for weeks. What has been much less clear is how those storms affect the ocean’s role in the carbon cycle. Do tropical cyclones help the ocean absorb carbon, or do they cause it to release more back into the atmosphere?

A new study suggests the answer is not simple, and it may also be changing.

A role reversal for tropical cyclones

The study was led by experts at the National University of Defense Technology (NUDT), Chinese Academy of Sciences, the NSF National Center for Atmospheric Research, and the GEOMAR Helmholtz Centre for Ocean Research Kiel.

The team pulled together a large set of observations to build a globally available daily dataset of air-sea CO2 flux. Using that, they were able to track how tropical cyclones have influenced the exchange of carbon between the ocean and the atmosphere over time. Their conclusion is that tropical cyclones have tended to push carbon out of the ocean and into the air. But that effect has been weakening in recent decades, and if warming continues under high emissions, the role of these storms may eventually flip.

A messy carbon signal

At first, the result sounds a little counterintuitive. The researchers found that tropical cyclones generally cause net ocean carbon outgassing. The main reason is that the intense winds of a cyclone greatly strengthen the transfer of CO2 from sea to air. But there is another process happening at the same time. After a tropical cyclone passes, it often leaves behind a cold wake, a patch of sea surface that has cooled because the storm mixed the upper ocean so strongly. That cooling can increase the ocean’s ability to take up carbon dioxide from the atmosphere, partly offsetting the carbon being released. Tropical cyclones are doing two things at once: they are helping CO2 escape because of their winds, while also setting up conditions that can later encourage carbon uptake.

The new study suggests that, historically, the first effect has usually won out. Even so, that balance has not stayed fixed.

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Reduction of tropical cyclone-induced ocean carbon outgassing since 1993

Published 29 May 2026 Science Leave a Comment
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The ocean is a major sink of anthropogenic carbon, absorbing 20~30% of anthropogenic CO2 emissions across the air–sea interface. Intense weather systems, such as tropical cyclones, can strongly perturb the upper ocean and thus critically influence this carbon transfer. Here we develop an approach of synthesizing various observations to quantify the role of tropical cyclones in the global carbon cycle. Two primary, but competing effects are: (1) CO2 efflux (from the ocean to atmosphere) during tropical cyclone passage and (2) CO2 influx after tropical cyclones, associated with disturbed carbon disequilibrium by mixing upwards of colder water (cold wakes). The CO2 efflux more than offsets the influx, resulting in net ocean carbon outgassing to the atmosphere. Annual tropical cyclone-induced carbon outgassing has decreased over the past three decades, from 0.09 ± 0.02 PgC in the 1990s to 0.05 ± 0.01 PgC in the 2010s. A strengthening of the vertical temperature gradient in the upper ocean due to anthropogenic climate warming leads to cold wakes with more intense surface cooling and increased carbon uptake after tropical cyclones. This has implications as the vertical temperature gradient continues to grow under high-emissions scenarios, tropical cyclones will cause net increasing ocean carbon uptake and more severe ocean acidification.

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Darkness and body size shaped end-Cretaceous marine extinction patterns

Published 29 May 2026 Science Leave a Comment
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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.

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Effects of acidified seawater on growth, nutritional condition, and olfactory sensory of the Asian seabass (Lates calcarifer) larvae

Published 28 May 2026 Science Leave a Comment
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Marine ecosystems are increasingly vulnerable to multiple stressors associated with climate change, resulting in significant ecological impact including ocean acidification. A 30-day experiment was conducted to investigate the effect of acidified seawater on the growth performance, nutritional status and free neuromast of olfactory organ condition of early larval stage of Asian seabass (Lates calcarifer) larvae. In this experiment, carbon dioxide (CO2) gas was introduced to lower seawater pH, and a timer system was installed to maintain the pH within specific ranges (5.5, 6.0, 6.5, and 7.0) while, a control treatment (pH fluctuating from 7.8 to 8.5) was also set, mimicking the current pH value of the seawater. Asian seabass larvae (initial total length: 2.13 ± 0.23 mm) were stocked at 30 individual/L in a 7L experimental aquarium in triplicate. The highest survival rate was obtained by Asian seabass larvae reared in control treatment 30.9±8.6% %, while total mortality was observed in pH 5.5 as early as day 1, followed by pH 6.0 and 6.5 at day 2 and 7.0 at day 5, respectively. The larvae in control group showed significantly better growth (14.25±1.02 mm) with excellent nutritional condition. Meanwhile, exposure to acidified seawater significantly reduced the length and density of larval olfactory neuromast hair cells compared to the control. It was concluded that acidified seawater induced mortality at early stage and triggered poor morphological development, resulting from inadequate nutritional condition and impaired sensory function.

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Long term variability of temperature and pH in the Bay of Bengal: an investigation on acoustic perspective

Published 28 May 2026 Science Leave a Comment
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This study comprehensively assesses the long-term variability of temperature, ocean acidity changes, and their implications on sound absorption and acoustic propagation in the Bay of Bengal. The analysis reveals a persistent warming trend in the Indian Ocean over the past 50 years, with a significant increase in temperature observed during the Sagar Maitri cruise in 2019. Thermal structure analysis using HadleySST EN4 data indicates warming in the upper 50m but a cooling trend in the 100-200m depth range. Oceanic Heat Content analysis highlights an increasing tendency of heat storage in the upper 50m, indicative of global warming.

In the context of surface ducted propagation, Sonic Layer Depth (SLD) and gradients in the Sound Speed Profile (SSP) were crucial factors influencing acoustic energy behavior. The study revealed a decreasing trend in in-layer gradient (Gr_SL) since 1990, intensifying after that period. The below-layer gradient (Gr_BL) also exhibited a decreasing trend, implying complex dynamics in the sonic layer with potential implications for sound propagation in the surface duct.

The investigation into pH changes spanning 65 years demonstrates a declining trend, particularly since the 1990s, attributed to increased atmospheric CO2 dissolution. The study linked this decrease to anthropogenic activities, aligning with global trends. The analysis of sound absorption illustrated a nonlinear relationship between absorption, frequency, and pH, emphasizing a significant impact of ocean acidification on sound absorption in the Bay of Bengal. The acoustic propagation modeling further highlighted a decrease in transmission loss with reducing pH, leading to increased sound travel and potentially noisier oceans. Salinity variations play a more significant role than temperature in influencing sound absorption.

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A review of volcanic activity and the evolution of coral reefs

Published 27 May 2026 Science Leave a Comment
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Coral reefs are among the most extraordinary ecosystems on Earth. They are living structures built by countless tiny polyps, yet they rival tropical rainforests in biodiversity, productivity, and ecological importance. They are subject to global, well-known, nonhuman disturbances, such as intense ocean currents, storm impacts, extreme weather events, climatic variations, disease, and predator outbreaks. They are recognized by the global human society for their care and preservation in a variety of Protected Areas. Coral reefs are also affected by the deleterious effects of diverse human activities, including local activities such as fisheries and tourism, and regional activities such as deforestation – illustrated by the unexpected impact of large logs on the coral crest – agriculture, the oil industry, coastal urban development, river outflow quality and quantity, nutrients, and contaminants. These factors collectively cause a harmful synergistic effect. Additionally, coral reefs are vulnerable to the long-term effects of climate change, including sea level rise, acidification, and high temperatures. Over evolutionary timescales, several forces have shaped coral reefs. For instance, Hamilton et al. [1] note that deforestation on tropical islands releases sediments that travel through rivers into the ocean. These sediments settle into reef crevices, effectively “suffocating” the habitat. Furthermore, this research emphasizes that water quality is degraded not only by land-based runoff (sedimentation) but also by the transport of agricultural nutrients. These nutrients promote macroalgal blooms, which directly compete with coral for space and sunlight. Knowledge of volcanic activity today still focuses on human risk to infrastructure and human life, while attention to potential effects on natural resources remains minimal. For example, Loughlin et al. [2] discuss how risk is calculated based on “Exposure” and “Vulnerability,” traditionally measured by human population density and capital assets.

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Feeding and excreting ecology in coastal systems

Published 26 May 2026 Science Leave a Comment
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Oysters (Crassostrea virginica) are critical foundation species in estuaries, providing numerous ecological and economic benefits. However, oyster populations have diminished worldwide. Effective oyster restoration and aquaculture require a mechanistic understanding of the physiological and environmental factors that govern oyster feeding, growth, and resilience under changing coastal conditions. We investigated how oyster ploidy and environmental conditions influenced oyster feeding and investigated how changes in abiotic conditions affected behavioral performance of oyster drills (Stramonita spp.), a key oyster predator. To better understand feeding responses and behaviors of both predator and prey we 1) used in-situ filter feeding assays to determine feeding differences existed amongst diploid and triploid oysters, 2) gathered a baseline for growth and in-situ feeding rates of oysters across Mississippi Sound in the Northern Gulf in the Spring, Summer, and Fall, 3) simulated present-day and projected future pH conditions (7.0-8.8) to analyze oyster feeding responses, and 4) introduced oyster drills to acidified conditions (7.0-8.8) to monitor behavior and foraging rates. Diploid oysters exhibited higher overall feeding rates, yet equivalent absorption efficiency between ploidies demonstrates a difference in energy allocation which might be the key to triploids’ ability to grow quickly. These findings highlight the role of intrinsic genetic and physiological traits in shaping oyster performance and provide a baseline for interpreting responses to environmental variability. Across spatial and seasonal variation in oyster in-situ feeding and growth across three contrasting sites in Mobile Bay and Mississippi Sound, in the Northern Gulf on the western border of Alabama and Mississippi, results revealed strong spatial and seasonal variability in feeding and growth. This was driven primarily by seston composition and salinity. Under present-day and projected future ocean acidification conditions, overall oyster feeding rates declined with lower pH’s, absorption efficiency remained stable, suggesting partial physiological compensation. These results indicate that pH can impose sublethal constraints on energy acquisition and growth, with individual variability at extreme pH highlighting potential acclimation or tolerance thresholds. When subjecting the oyster’s predator, the oyster drill, to similar pH conditions (7.0-8.8) experimental results indicate that decreased pH may increase drill foraging times. Behaviors like inactivity and climbing out of the water indicate a stress response under both high and low pH, demonstrating the complexity of predicting predator-prey outcomes under more acidic conditions. Collectively, these chapters demonstrate that oyster feeding, growth, and survival are shaped by both intrinsic traits, such as ploidy, and extrinsic factors including environmental variability and ocean acidification. Understanding the interplay between physiological plasticity, seston quality, and predator-prey interactions is essential for informing restoration and aquaculture strategies that sustain ecological function and the ecosystem services oysters provide.

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Demonstration of an automated bioreactor for controlled acid dosing to enhance marine algae productivity

Published 26 May 2026 Science Leave a Comment
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Microalgae are an important feedstock in aquaculture with significant economic potential in generating a diversity of bioproducts. To facilitate expansion of microalgal cultivation, a continuous automated bioreactor that uses waste acid to increase carbon bioavailability in seawater for enhanced biomass production was designed and tested with Tetraselmis suecica UTEX2286. Carbon bioavailability was inferred from culture pH and bioreactor headspace CO2 concentration measurements and controlled via acidification and seawater dilution. Operating over a period of several days, the culture exhibited greater biomass productivity at a pH setpoint of 7-7.5. Outside of this range, algal activity slowed, accompanied by greater CO2 released to the headspace and lower pH during incubation. Increasing the carbon introduced to the bioreactor by increasing the dilution factor did not significantly increase the algal productivity. Importantly, acidification led to statistically significant gains in biomass productivity. Preliminary cost analysis showed while seawater is inexpensive, the acid cost drives the overall cost of the designed bioreactor system. Thus, the designed bioreactor and control scheme supports algal cultivation but requires low-cost acid to be economical, which may be achieved by strategically integrating microalgae cultivation with other coastal industries.

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Microbial communities associated with two populations of the sponge Chondrilla nucula under present and projected climate conditions in the Aegean Sea

Published 25 May 2026 Science Leave a Comment
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This data paper describes bacterial and fungal communities associated with the sponge Chondrilla nucula collected from two Eastern Mediterranean populations (North and South Aegean Sea) and maintained under controlled common-garden conditions simulating present and projected climate scenarios over a period of 3 months. Microbial composition was characterised using two complementary ribosomal marker approaches: Illumina (MiSeq) sequencing of the 16S rRNA gene for Bacteria and Oxford Nanopore (MinION) sequencing of a long 18S-ITS-28S rRNA fragment for Fungi. A total of 24 sponge libraries (3 climate conditions x 2 populations x 4 biological replicates) along with six control libraries (water from three experimental tanks, extraction and PCR blanks) were constructed for each group of microsymbionts. The resulting reads were processed using custom and publicly available bioinformatic pipelines and databases, followed by initial taxonomic assignment. This dataset represents the first fungal community associated with C. nucula and the first bacterial community for this species from the Aegean Sea.

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Carbon allocation strategy of Thalassiosira weissflogii in response to elevated pCO2

Published 25 May 2026 Science Leave a Comment
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Diatoms are of significance in the marine ecosystem, playing a pivotal role in the sustenance of marine life and the transfer of carbon from the surface ocean to deeper waters. Although numerous studies have investigated the effects of elevated carbon dioxide (CO2) on marine diatoms across both short- and long-term adaptation scales, the molecular mechanisms governing chitin metabolism in response to ocean acidification remain poorly understood. In this study, we employed an integrated approach combining transcriptomic, metabolomic, and physiological analyses to examine the marine diatom Thalassiosira weissflogii following 40-day acclimation to high-CO2 conditions. Physiological studies have demonstrated that ocean acidification has the capacity to result in an augmentation of the C/N ratio, chitin content, maximum PSII quantum yield (Fv/Fm), and photosynthetic pigment content of T. weissflogii. Analysis of chlorophyll fluorescence dynamics further demonstrated enhanced primary photochemical efficiency of PSII in the acidified treatment group. Consistent with this, the transcriptome results also showed that the photosynthesis-related pathways were upregulated to meet the increased material and energy requirements after adaptation to elevated CO2 levels. More importantly, it was determined that acidification treatment resulted in the upregulation of chitin synthesis and the downregulation of chitin degradation in T. weissflogii, consequently leading to an augmentation in chitin content. These findings indicate that ocean acidification (high CO2, low pH) prompts T. weissflogii to prioritize the allocation of carbon resources to the synthesis of chitin. The synthesis of chitin may reinforce cell wall formation as an adaptive response to ocean acidification. Our research provides new insights into the marine acidification adaptation strategies of T. weissflogii.

Continue reading ‘Carbon allocation strategy of Thalassiosira weissflogii in response to elevated pCO2’

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