The study, led by Tobias Walla of the IRD research institute in Nouméa, New Caledonia, together with colleagues from the University of Angers, Aix-Marseille University, Lille University, and CSIRO Data61 in Australia, was published in the Journal of Micropalaeontology. The researchers trained convolutional neural networks, or CNNs, to automatically identify living, Rose Bengal-stained benthic foraminifera at the species level, drawing on sediment samples from two strikingly different coastal environments: a low-diversity intertidal mudflat in Bourgneuf Bay on the French Atlantic coast and a high-diversity set of Mediterranean sites along the southern French coast and Corsica. It is, according to the authors, the first application of machine learning to the identification of living benthic foraminifera from coastal sediments.

The technical pipeline begins with a piece of equipment that would look at home in any hobbyist’s workshop: a modified 3D printer. Stripped of its printing function and fitted with a 5-megapixel Basler camera, a telecentric lens with 4x magnification, and a ring light for constant illumination, the printer’s moving head becomes a precision gantry that scans micropalaeontological slides in the X, Y, and Z directions. The system, nicknamed Sashimi, captures stacks of images at fixed exposure and step intervals, which are then fused into fully focused composite pictures using Helicon Focus software. A complete scan of a single slide takes roughly an hour and a half, and the entire build instructions are freely available on GitHub, making the setup a genuinely low-cost alternative to dedicated imaging rigs.

Because a single field of view can contain many specimens, the team first needed a way to isolate individual foraminifera from the background clutter of glue residues, grid lines, and other particles. They annotated images using the open-source Computer Vision Annotation Tool and trained a faster region-based convolutional neural network, built on a ResNet50 backbone pre-trained on the COCO dataset, to draw bounding boxes around every foraminifer. The detection step performed impressively. On the Atlantic slides, the model missed only one specimen out of 381, achieving an accuracy and recall of 99.74 percent and a perfect precision score. On the Mediterranean slides, it caught 129 of 131 specimens, with a recall of 98.47 percent, though it also flagged 30 false positives, mostly glue and debris that would later be filtered out during classification.

With individual specimen images extracted, the researchers labeled more than 13,000 of them using the ParticleTrieur software and trained three classification models. The first, trained on the Atlantic MUDSURV dataset of 6,375 images covering six species, distinguished species regardless of vital status and reached an accuracy of 96.0 percent, with a precision of 96.1 percent and a recall of 95.5 percent. Five of the six species were recognized with accuracies above 96 percent, and the morphologically distinctive agglutinated Ammobaculites balkwilli and the monothalamid Psammophaga were classified perfectly. The trickiest case was Elphidium selseyense, which was confused with its close relatives Ammonia confertitesta and Elphidium oceanense in a minority of cases, a reminder that even algorithms struggle with the taxonomic fine print that vexes human experts.

The second Atlantic model tackled a problem no automated foraminifera classifier had attempted before: separating living from dead specimens of the same species. Rose Bengal staining, the standard technique in biomonitoring, colours the cytoplasm of living individuals pink, but faded stains, discoloured tests, and human inconsistency in labeling made this a harder task. Nevertheless, the model distinguished ten classes, combining species and vital status, with an accuracy of 94.2 percent. Eight of the ten classes scored above 90 percent, and only dead Ammonia confertitesta and dead Elphidium fell below that mark, at 80 and 86 percent respectively. Species recognition, the authors note, remained consistently easier than vital status determination, partly because the training labels themselves carried the bias of human experts who do not always agree on how much staining counts as alive.

The Mediterranean challenge was steeper. The MEDIT dataset comprised 7,148 images spanning 63 species, many of them porcelaneous miliolids whose whitish shells nearly vanish against the white background of standard micropalaeontological slides. The resulting model achieved an overall accuracy of 82.2 percent, with 16 species recognized at better than 90 percent and seven, including Ammodiscus planus, Nonion scaphum, and Valvulineria bradyana, at a flawless 100 percent. But 12 species fell below 50 percent accuracy, and several porcelaneous taxa such as Biloculinella irregularis and Quinqueloculina spp. were never correctly predicted. When the model was applied to six independent test samples from a sewage outfall transect in Calvi Bay, Corsica, average accuracy dropped to about 69.7 percent, largely because the samples contained species the model had never seen during training.

Here is the twist that matters most for environmental managers: even with that imperfect species-level accuracy, the automated results translated into almost identical ecological verdicts. The team calculated the Tolerant Species Index, or TSI-Med, an index of ecological quality status that depends on identifying tolerant species and counting total living foraminifera. Of six test samples analyzed, only one shifted category, moving from very good to good. The tolerant species that drive the index, such as Cancris auricula and Leptohalysis scottii, happened to be among the best-identified taxa because ample training images were available. On the Atlantic side, the CNN tracked monthly abundance trends of the four dominant species closely enough to detect reproduction events, including two high-density blooms in October 2020, with the model correctly identifying them at 67 percent accuracy.

The speed gains are hard to overstate. Once the models are trained, applying them to a full dataset takes less than a minute on an ordinary laptop, compared with hours of expert picking and counting for each sample. That opens the door to the kind of high-temporal-resolution monitoring that seasonal population dynamics demand but manual workflows cannot deliver. International biomonitoring protocols such as FOBIMO recommend annual sampling with three replicates per station, yet most real studies span multiple stations sampled monthly or seasonally, generating overwhelming workloads. Automated imaging and classification could also reduce operator-dependent taxonomic bias, a documented problem in foraminiferal science, where studies have shown that even experienced identifiers disagree on planktonic species at median cross-recognition accuracies of around 79 percent.

The authors are careful about the limits. The current workflow still requires specimens to be picked and glued onto slides before scanning, though extending it to raw sieved sediment is the obvious next step. Rose Bengal staining fades over time in dried slides, so rapid scanning after picking is essential, and porcelaneous and agglutinated groups remain problematic on white backgrounds, prompting plans to test alternative slide colours. The reliability of the CNNs rests on hundreds to thousands of expertly labeled images, which underscores that taxonomists remain indispensable. Still, the demonstration that a machine can distinguish living from dead foraminifera, and do so fast enough to support large-scale monitoring programs, marks a genuine turning point for these humble shelled amoebae, which may soon be reporting on the health of coastal oceans at a pace their human interpreters could never match.

Subject of Research: Automated deep learning identification of living benthic foraminifera for coastal biomonitoring

Article Title: Identification of living (Rose Bengal)-stained benthic foraminifera using automated image recognition

Article References: Identification of living (Rose Bengal)-stained benthic foraminifera using automated image recognition. (n.d.). https://doi.org/10.5194/jm-45-623-2026

Image Credits: AI Generated

DOI: 10.5194/jm-45-623-2026

Keywords: foraminifera, deep learning, convolutional neural networks, Rose Bengal staining, biomonitoring, bioindicators, automated imaging, coastal ecosystems, micropalaeontology, ecological quality, machine learning, ocean health

The research team, led by Anna B. Tureţcaia and Emily B. Graham of Pacific Northwest National Laboratory, together with colleagues from the National Estuarine Research Reserve System, the University of Wisconsin–Madison, and San Francisco State University, set out to answer a deceptively simple question: what makes an estuary resist a storm? They defined resistance as the magnitude of ecosystem change induced by a precipitation event, focusing on dissolved oxygen as an integrative indicator of estuarine function. Dissolved oxygen is the currency of aquatic life, sustaining fish, invertebrates, and the microbial communities that drive carbon and nutrient cycling, and it responds rapidly to shifts in temperature, salinity, nutrient loading, and water movement. A system that maintains stable oxygen concentrations through a hurricane or atmospheric river is, by this measure, a stable system.

To quantify that stability, the team turned to a long-running treasure trove of environmental data. Five estuaries in the National Estuarine Research Reserve System — Lake Superior in Wisconsin, Chesapeake Bay’s Jug Bay in Maryland, Guana Tolomato Matanzas in Florida, Weeks Bay in Alabama, and San Francisco Bay in California — provided more than 150,000 salinity records per site and continuous 15-minute measurements of dissolved oxygen, temperature, turbidity, and water depth from synchronized sondes. Monthly grab samples supplied nutrient and chlorophyll-a concentrations. The five systems span a remarkable range of conditions, from the freshwater seiche-driven St. Louis River mouth at Lake Superior to the semi-diurnal tidal embayments of San Francisco Bay, with salinities ranging from 0.1 to 35 parts per thousand.

The researchers selected one wet and one dry year for each estuary using decades of airport precipitation records, then identified major precipitation events within those years — hurricanes Matthew and Irma, tropical storms, Nor’easters, and atmospheric rivers among them. For each event, they calculated a resistance index, a normalized value between −1 and +1 originally developed for soil ecology, which compares the shift in dissolved oxygen after a disturbance to the pre-disturbance baseline. A value of +1 signals perfect resistance; values near zero mean the storm-induced change matched the size of the baseline itself. In total, they computed resistance for dozens of events across 19 monitoring locations, then searched for patterns using linear regressions at three scales: continental, salinity-based groups, and within each individual estuary.

The headline surprise emerged immediately. San Francisco Bay, the most urbanized estuary in the study, posted the highest mean resistance at 0.66, while Weeks Bay, dominated by agricultural land, was the least resistant at 0.23. Across all five estuaries combined, resistance rose with the percentage of built area and with population density within a 10-kilometer zone around each monitoring station — a result directly opposite to the team’s original hypothesis that urbanization would erode estuarine stability. Precipitation events generally pushed dissolved oxygen downward at San Francisco Bay and Chesapeake Bay’s Jug Bay, but the shifts were small relative to baseline variability. At Lake Superior, the least urbanized system, storms actually increased dissolved oxygen significantly.

Why would concrete and population density appear to buffer an estuary against storms? The authors propose two non-exclusive explanations, both sobering. First, urban watersheds may genuinely dampen oxygen swings: increased hydrological flashiness boosts reaeration and can flush phytoplankton out of the system or suppress them through turbidity-driven light limitation. Since algal blooms generate large day-night oxygen oscillations — supersaturation by day, depletion by night — curbing phytoplankton overgrowth could keep dissolved oxygen closer to baseline. Supporting this mechanism, the study found turbidity was positively related to built area, and chlorophyll-a was negatively related to population density. Second, and more troubling, urban estuaries may simply be so chronically disturbed that a storm adds little new stress. If baseline dissolved oxygen already fluctuates wildly due to nutrient loading and wastewater inputs, an additional precipitation-driven perturbation may not register as a significant departure. In that scenario, high resistance is not health — it is the signature of a system already pushed far from its natural state.

Beyond urbanization, several physicochemical factors showed consistent associations with resistance across scales. Water column depth and turbidity were positively related to resistance, while water temperature and chlorophyll-a were negatively related, patterns that held at the continental scale, within salinity groups, and within individual estuaries. Deeper water bodies can dilute freshwater inflows, buffer temperature swings, and moderate gas exchange, though depth cuts both ways: it can also strengthen stratification and starve bottom waters of oxygen. Warm water holds less oxygen and accelerates microbial respiration, while high chlorophyll-a signals phytoplankton abundance and the volatile oxygen dynamics that come with it. The negative temperature relationship was the strongest continental-scale pattern, explaining roughly 42 percent of the variance in resistance.

Yet the deeper message of the study is that these broad generalizations dissolve as the lens zooms in. When estuaries were grouped by salinity, relationships strengthened and new predictors appeared: in high-salinity systems, resistance tracked dissolved inorganic nitrogen, the nitrogen-to-phosphorus ratio, built area, and even tree cover, with several relationships explaining more than half the variance. In low-salinity systems, cropland emerged as a significant factor. Within individual estuaries, the picture fragmented further. Resistance at Guana Tolomato Matanzas correlated with five different factors, three of which never appeared at the continental scale, while at Chesapeake Bay’s Jug Bay only water column depth mattered. Salinity was positively associated with resistance at two estuaries and negatively at a third. The direction of the depth relationship itself flipped between systems. In short, no single rulebook governs how an estuary absorbs a storm.

From these patterns the team sketched a conceptual model to guide future work. The highest resistance, they suggest, should be expected in tidal-dominated or urban-influenced estuaries that are well mixed and have short residence times, where tides rapidly homogenize storm-driven perturbations in salinity, turbidity, and nutrients — San Francisco Bay being the archetype. The lowest resistance should occur in enclosed, shallow, poorly mixed systems with long residence times and strong river or agricultural influence, such as Weeks Bay or the stratified Pellicer Creek in Florida, where storm-induced changes linger and oxygen fluctuations amplify. Most real estuaries, the authors caution, fall somewhere along this continuum, and the model is intended to generate hypotheses rather than serve as a deterministic classification.

The practical stakes are considerable. With urban populations growing and extreme precipitation intensifying across North America, coastal managers need to know which estuaries are most likely to tip into hypoxia, fish kills, and disrupted nutrient cycling after major storms. This study argues that neither a blanket urbanization penalty nor a blanket urbanization exemption will do; management strategies must pair continental-scale generalizations with local knowledge of salinity regime, stratification, nutrient speciation, and watershed land cover. It also flags dissolved nitrogen dynamics and microbial activity as priority targets for the mechanistic research needed to explain why urban estuaries appear so storm-hardy. And it delivers a cautionary lesson in measurement itself: an ecosystem can look remarkably stable precisely because it has already been degraded. Resistance, the authors remind us, is a normalized number that says nothing about whether the underlying ecological state is thriving. As storms grow stronger and cities expand, distinguishing genuine resilience from the numbness of chronic disturbance may become one of the most important tasks in coastal science.

Subject of Research: Estuarine resistance to precipitation events across urbanization gradients and spatial scales

Article Title: Physicochemical and urban land-use characteristics associated with resistance to precipitation in estuaries vary across scales

Article References: Physicochemical and urban land-use characteristics associated with resistance to precipitation in estuaries vary across scales. (n.d.). https://doi.org/10.5194/bg-23-7009-2026

Image Credits: AI Generated

DOI: 10.5194/bg-23-7009-2026

Keywords: estuaries, dissolved oxygen, urbanization, precipitation, resistance index, land use, nutrients, chlorophyll-a, salinity, water quality, Biogeosciences, coastal ecosystems

The technical backbone of the analysis is a classic bibliometric toolkit. The researchers, led by Matheus Cavalcante-Silva of Fluminense Federal University in Brazil, applied Price’s Law, a foundational principle of scientometrics which holds that productive research fields grow exponentially rather than linearly. When the team fitted growth curves to the annual publication counts, the exponential model explained roughly 97.8 percent of the variance in the data, outperforming a linear fit by a factor of about 1.5. In plain terms, the number of studies on mangrove sediment carbon has been compounding year after year, much like the accumulation of the carbon itself in the waterlogged soils these papers describe. Citation dynamics tell the same story: the corpus has amassed 163,819 citations, with 88.8 percent of them accrued in just the last decade of the study window.

The recency of that citation activity is captured by the Price Index, which measures the share of citations less than five years old. A value near 50 percent signals a vibrant, current literature; this field scored 66.2 percent, placing mangrove sediment carbon research squarely at the center of contemporary environmental science rather than on its margins. For comparison, the team also ran exploratory polynomial regressions on cumulative publication counts. A third-order polynomial, with a coefficient of determination of 0.9998, projected a possible 6.7-fold increase in research output over the next two decades, though the authors are careful to frame such extrapolations as exploratory rather than deterministic forecasts. A sixth-order model produced more conservative estimates and showed signs of overfitting, capturing statistical noise around 2023 rather than genuine signal.

Geographically, the field is dominated by two scientific superpowers. The United States leads with 1,656 articles, representing 17.9 percent of country-level records, followed by China with 1,305 articles, or 14.1 percent. In total, 144 countries contributed to the literature, but the concentration at the top reflects deep institutional capacity and sustained funding. The Chinese Academy of Sciences alone accounted for 520 articles, the single most prolific institution, while the National Natural Science Foundation of China topped the funding agencies with support attached to 803 articles, ahead of the United States National Science Foundation with 534. The authors attribute this dominance to a dual relevance: mangroves in these regions are simultaneously recognized as efficient carbon sinks and as ecosystems under intense anthropogenic pressure from urbanization and hydrological alteration, a combination that keeps research dollars and policy attention flowing.

The disciplinary spread is equally telling. Publications span 25 major subject areas, led by Agricultural and Biological Sciences with 27.7 percent of records, Environmental Science with 26.5 percent, and Earth and Planetary Sciences with 19.5 percent. Journal output concentrates in outlets such as Biogeosciences, which published 265 articles, the Journal of Geophysical Research Biogeosciences, and Science of the Total Environment. Among individual researchers, Carlos M. Duarte emerges as the most prolific contributor with 47 publications, followed closely by Catherine E. Lovelock with 46 and Christian J. Sanders with 38, names that have become synonymous with the conceptual foundations of marine vegetated ecosystem carbon science.

Perhaps the most revealing part of the analysis is its mapping of collaboration networks. Using VOSviewer clustering on co-authorship links among 45 connected authors, the team identified seven distinct but interconnected thematic communities. The earliest clusters center on microbial pathways and early diagenesis, the suite of chemical and biological reactions that transform organic matter in oxygen-starved sediments, and on sedimentary carbon storage and source partitioning, where stable isotopes and elemental ratios distinguish carbon produced within the mangrove from carbon washed in from elsewhere. Other clusters address large-scale carbon cycling and climate-driven controls, ecosystem functioning and sequestration, hydrodynamic fluxes at the sediment-water interface, and finally ecosystem-scale blue carbon frameworks that tie local biogeochemistry to regional and global carbon budgets.

The temporal overlay of these networks documents a striking intellectual evolution. Early research was anchored in mechanistic studies of anoxic sediments across many wetland types, not exclusively mangroves, establishing the experimental foundations for understanding carbon turnover. As networks expanded and cross-cluster collaboration intensified, the focus shifted toward integrative perspectives in which biogeochemical reactions, sediment dynamics, and physical transport were treated as coupled regulators of carbon fluxes. In the most recent phase, the field has pivoted decisively toward climate-relevant and policy-facing work, connecting sediment biogeochemistry to carbon accounting, restoration science, and nature-based solutions. Keyword co-occurrence analysis of roughly 250 terms reinforces this arc: terms tied to microbial decomposition and early diagenesis dominated the early literature, while carbon storage, greenhouse gases, and climate change now co-occur with increasing frequency.

Why do mangrove sediments punch so far above their weight? The answer lies in a convergence of factors documented across the comparative literature the review synthesizes. Mangroves occupy less than 2 percent of global coastal area, yet their sediments can hold between 50 and nearly 100 percent of total ecosystem carbon, preserved for centuries to millennia. Soil carbon densities commonly range from about 100 to more than 300 megagrams of carbon per hectare in the upper meter, with some Amazonian and Southeast Asian sites exceeding 300 and even reaching 450 megagrams per hectare. The mechanistic explanation combines high organic carbon inputs from primary production, persistent waterlogged anoxia that suppresses decomposition, and physical and biogeochemical protection of organic matter. By contrast, river delta wetlands show more heterogeneous stocks of roughly 50 to 200 megagrams per hectare, and reef lagoon systems generally hold less, constrained by hydrodynamic exposure.

The review is candid about the complications. Sedimentary carbon stocks are highly sensitive to methodology: core depth integration, dry bulk density assumptions, and analytical protocols can swing estimates substantially, meaning shallow cores and assumed densities often lead to underestimation. Biogenic structures such as crab burrows and root systems reshape microscale redox conditions, and microbial communities operate across aerobic and anaerobic pathways, including iron, manganese, nitrate, and sulfate reduction as well as methanogenesis, mediating the delicate balance between carbon remineralization and long-term stabilization. Anthropogenic pressures, from urban organic loading to aquaculture, can tip this balance toward enhanced greenhouse gas production. The authors flag the persistent challenge of linking millimeter-scale microbial heterogeneity to ecosystem-scale carbon dynamics as the field’s central unresolved question, and suggest targeted secondary syntheses of clustering hotspots, particularly around microbial communities and methanogenesis, as the most promising next step.

What emerges from this quantitative portrait is a maturing discipline in transition. Mangrove sediment research has moved from describing how organic matter degrades to explaining how carbon persists, and from isolated process studies to frameworks that inform national carbon accounting and coastal restoration policy. With research output projected to keep climbing, and with mangroves increasingly written into climate mitigation strategies from carbon markets to national pledges, the muddy sediments beneath these tidal forests are no longer a scientific backwater. They are, by every bibliometric measure, one of the fastest-growing and most policy-relevant frontiers in environmental science, and the global research community is only beginning to excavate their full significance.

Subject of Research: Scientometric analysis of global research on mangrove sediments as long-term blue carbon sinks

Article Title: Mangrove sediments as carbon sinks: a global analysis of research patterns, trends and future directions

Article References: Cavalcante-Silva, M., Santos-Lima, A. C., Fonseca-Oliveira, A. L., Meira, V. L., Monte, C. D. N., & Machado, W. (2026). Mangrove sediments as carbon sinks: a global analysis of research patterns, trends and future directions. Environmental Science and Pollution Research, 33(30), 15211-15228. https://doi.org/10.1007/s11356-026-38224-7

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38224-7

Keywords: mangroves, blue carbon, carbon sequestration, sediments, scientometrics, bibliometrics, climate change mitigation, microbial decomposition, early diagenesis, nature-based solutions, coastal ecosystems, greenhouse gases

The scale of the problem facing oyster reefs provides the backdrop for the new valuation. Worldwide, an estimated 85 percent of oyster reefs have been lost over the past century, with the steepest declines concentrated in estuaries and river deltas, the very environments where these reef-building bivalves thrive. Like all coastal ecosystems, oyster reefs are under growing stress from overexploitation, pollution, and climate change. The United Nations’ Sustainable Development Goal on life below water calls for the conservation and sustainable use of coastal and marine resources to safeguard human wellbeing, yet the habitats that could deliver many of those benefits continue to disappear. The new study was designed to quantify exactly what is being lost, and what could be regained, if restoration were pursued at scale.

To build their global picture, the researchers, led by corresponding author Dr Matteo Convertino, an associate professor at Tsinghua University, began by assessing where suitable habitat for oyster reefs exists today and where reefs could spontaneously form given the right protection and restoration interventions. They imported thousands of geotagged records of oyster reefs from two public databases and then applied a well-established machine learning algorithm to predict geographic distributions and habitat suitability around the world, flagging potential new locations where reefs might be established. The suitability model weighed a suite of environmental variables, including local water temperature, salinity, light availability, nutrient richness, and oxygenation. Any location scoring 65 percent or greater on habitat suitability was classified as suitable for reef formation.

The team then went a step further, combining each area’s suitability score with a measure of the ecosystem services a reef there could provide to calculate what they call the ecopotential of every location. The higher the ecopotential, the greater the potential benefit of restoring or protecting a reef at that site. This portfolio of services extends far beyond oysters for human consumption. Oyster reefs filter enormous volumes of water, protect shorelines from erosion and storm damage, recycle nutrients through the food web, and sequester carbon. They also provide food, shelter, and nursery grounds for a plethora of fish and invertebrates, functioning as foundational habitat that supports entire coastal food webs. Capturing the full value of this portfolio is what pushes the estimated GEP into the trillions.

The modeling results identified ten hotspot nations where predicted ecopotential is greatest: the United States, Australia, Chile, China, Japan, South Korea, Argentina, France, Germany, and Italy. Across these countries, approximately 295,000 square kilometers, or about 6 percent of their coastal zones, were deemed suitable for oyster reefs. Yet reefs are currently known to occupy only 10 percent of that suitable area, mainly in lagoons and bays, estuaries, and river deltas. The gap between what exists and what could exist points to enormous room for expansion. Perhaps more striking is the finding that only 23 percent of the suitable area currently falls under any form of marine protection, meaning the vast majority of remaining and potential reef habitat remains exposed to the pressures that have already erased most of the world’s oyster reefs.

The quantified benefits of full restoration are vivid when expressed in raw ecological terms. If every area with positive ecopotential were occupied by reefs, the authors calculate that these ecosystems could filter prodigious volumes of water: 77.58 quadrillion liters in the United States, 69.92 quadrillion liters in Australia, and 46.58 quadrillion liters in Chile. Water filtration by dense aggregations of filter-feeding oysters improves clarity, removes excess nutrients, and can help suppress harmful algal blooms, cascading through coastal ecosystems in ways that benefit seagrasses, fish populations, and human users alike. The same fully realized reef network could sequester as much as 12.3 million metric tons of carbon per year, adding a meaningful climate mitigation component to the reefs’ portfolio of services.

For a single country, the monetary value of just a subset of these services is already substantial. In the United States alone, the combined potential value of nitrogen removal, carbon sequestration, and water purification by oyster reefs was estimated at 25.1 billion dollars a year. Nitrogen removal matters because coastal eutrophication, driven by agricultural and urban runoff, is one of the most damaging forces in estuarine systems worldwide, and oysters incorporate and process nitrogen as they filter and grow. Carbon sequestration reflects the burial of organic material in reef structures and surrounding sediments. Water purification, meanwhile, underpins fisheries, tourism, and coastal water quality. These three services represent only part of the total portfolio, which is why the global GEP estimate reaches into the trillions when all services and all suitable nations are considered.

The authors are careful to frame these figures as estimates rather than guarantees. The calculations infer ecosystem services from global averages of key parameters, and the actual values could shift with changes in oyster populations over time or with the advancing climate crisis. Significant work on habitat restoration and protection would also be required before any of the potential could be unlocked. We estimated that 90 percent of sites suitable for oyster reefs require restoration, while 80 percent need protection through conservation efforts, Convertino said. In other words, the current oyster situation is very suboptimal, but there is a huge opportunity, considering the benefits. The statement captures the central tension of the study: the ecological and economic potential is enormous, but realizing it demands investment and policy action on a comparable scale.

Climate change adds a further layer of complexity to the outlook. Because global warming generally decreases the habitat quality of oyster reefs, the researchers expect the global GEP to decline from the current potential value of twelve trillion dollars as conditions shift. Yet the picture is not uniformly negative. Some countries may see an expansion of reefs due to more favorable conditions for the growth and dispersal of oysters. The study singles out Australia, Indonesia, South Korea, Japan, and France as places where reef extent could grow under warming conditions, a reminder that the biogeography of coastal ecosystems will be reshuffled rather than simply diminished. For policymakers, the implication is that restoration priorities may need to be dynamic, tracking shifting habitat suitability over decades.

What the study ultimately offers is a new way of seeing an ecosystem that most people encounter only on a dinner plate. By translating the ecological work of oyster reefs into the language of gross ecosystem product, the researchers make a case that resonates in ministries of finance as much as in marine biology laboratories. A reef that filters quadrillions of liters of water, sequesters millions of tons of carbon, buffers shorelines, and nurseries commercial fish stocks is not a luxury but infrastructure, and infrastructure that has been allowed to collapse by 85 percent in a single century. The twelve trillion dollar figure is not a promise but a ceiling, one that depends on restoring nine tenths of suitable sites and protecting four fifths of them. Whether the world’s nations choose to make that investment will determine whether oyster reefs remain a remnant of past coastlines or become a cornerstone of future planetary health.

Subject of Research: Global valuation of the gross ecosystem product of oyster reefs

Article Title: The world’s oyster reefs could add $12 trillion to planetary health each year – if they were better managed

Article References: The world’s oyster reefs could add $12 trillion to planetary health each year – if they were better managed. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: oyster reefs, ecosystem services, gross ecosystem product, marine restoration, coastal ecosystems, water filtration, carbon sequestration, habitat suitability, machine learning, climate change, marine conservation, Frontiers in Marine Science

The research addresses a conspicuous gap in European environmental law. The European Union’s Marine Strategy Framework Directive, introduced in 2008 to protect marine ecosystems and biodiversity, was intended to cover a broad suite of human pressures on the sea, and light pollution was nominally among them. In practice, however, no defined criteria for Good Environmental Status with respect to ALAN have ever been established, which means member states have had no operational way to measure, monitor or manage the problem. Without such criteria, light pollution has remained what the study’s authors describe as a hidden environmental threat, one that is acknowledged in principle but ignored in regulatory terms. The new methodology is designed to close that gap by providing a scientifically grounded, operational and adaptable framework that can be applied with existing knowledge and tools.

Technically, the framework draws on an approach already developed for underwater noise, another form of marine pollution that is extensively covered in existing Marine Strategy Framework Directive guidance. The research team, working as part of the AquaPLAN project, developed separate risk scoring criteria for the water column and for the seabed, recognising that light behaves differently as it travels through clear versus turbid water and that different habitats and organisms are exposed at different depths. The scoring system takes into account the light pollution being emitted by coastal towns and cities, the optical clarity of the seawater in particular locations, and how easily light can penetrate downward through the water column. Where water is clear, artificial light from shore can reach considerably deeper and affect a larger volume of habitat; where it is turbid, penetration is reduced but scattering can still illuminate surface waters.

To produce the risk maps, the team combined these criteria with existing datasets, most notably the 2021 Global Atlas of Artificial Light at Night Under the Sea, which integrates satellite observations of nighttime lights with models of how that light propagates underwater. Each regional sea was then scored according to the percentage of its area exposed to nil, low, medium or high risk of harm. The result is a ranked league table of European sea regions ordered from highest to lowest exposure risk. The Adriatic Sea tops the list, followed by the Baltic Sea and the western Mediterranean Sea, with the Greater North Sea, the Aegean-Levantine Sea, the Ionian and Central Mediterranean Sea, the Black Sea and the Sea of Azov also ranking among the more exposed waters. At the opposite end of the scale sit Macaronesia, a region encompassing the Canary Islands, the Azores, Madeira and Cape Verde, along with the Barents Sea, the Iceland Sea, the Norwegian Sea and the White Sea.

The pattern that emerges is geometric as much as demographic. Enclosed regions bordered by land on several sides accumulate light from multiple densely populated coastlines simultaneously, and because the water cannot disperse or dilute the illumination the way open ocean can, the exposure risk compounds. The Adriatic, wedged between the Italian peninsula and the Balkans and fringed by major tourist destinations, exemplifies the problem. The Baltic, with its low-lying, heavily developed catchment and relatively shallow, partially enclosed basin, shows a similar signature. The western Mediterranean combines intense coastal urbanisation with some of the clearest water in Europe, allowing shore-based light to penetrate further into the water column than it would in murkier northern seas.

For the United Kingdom, the news is comparatively reassuring. The Greater North Sea and the Celtic Seas are largely characterised as being of medium to low risk, reflecting the moderating effect of open connections to the Atlantic and the relatively diffuse distribution of coastal light sources. Yet the assessment also flagged a distinctly industrial contributor: the North Sea’s oil and gas fields, and the infrastructure associated with them, add significant levels of light pollution to what would otherwise be an open ocean setting. Offshore platforms, flares and floodlit installations create islands of artificial brightness far from any coastline, illuminating waters that would naturally experience only moonlight and starlight. This finding underscores that marine light pollution is not solely a coastal phenomenon driven by tourism and urbanisation.

The scientific case for concern has been building for more than a decade. Dr Thomas Davies, Associate Professor of Marine Conservation at the University of Plymouth, led the first ever study into the effects of light pollution on the marine environment in 2014 and is the lead author of the new research. He argues that the accumulated evidence now justifies regulatory action. Over many years, he notes, research has repeatedly shown that light pollution is significantly impacting many important coastal species, yet it remains largely absent from global policy. The Marine Strategy Framework Directive was supposed to include measures linked to light pollution, but that never fully materialised, with the standing argument being that the evidence base was insufficient to support detailed legislation. Davies contends that this argument no longer holds, and that the study, together with the wider body of work since 2014, provides clear evidence of risk and harm that urgently needs to be translated into meaningful action.

Senior author Professor Tim Smyth, Director of Science at Plymouth Marine Laboratory, emphasises that defining and quantifying Good Environmental Status requires more than measurement alone. It depends, he says, on combining global observations and mapping with expert scientific judgement about what a healthy ocean should look like. The 2021 Global Atlas of Artificial Light at Night Under the Sea, together with the extensive evidence generated over the past decade, has made it possible to assess this emerging pressure at a global scale. Smyth frames ALAN alongside other under-regulated stressors such as underwater noise, arguing that together they help build a more complete picture of cumulative human impacts on the ocean and provide the evidence base for effective action ranging from global policy down to local management decisions.

The study was written by scientists from the University of Plymouth, the Centre for Environment, Fisheries and Aquaculture Science, the University of Pisa, the Genoa Marine Centre and the Italian Institute for Environmental Protection and Research, many of whom are also members of the Global Ocean Artificial Light at Night Network, known as GOALANN. The network was launched by Dr Davies and Professor Smyth at the United Nations Ocean Decade Conference in April 2024 and was later endorsed by the UN as one of its Ocean Decade Actions. Professor Elena Maggi, Professor in Ecology at the University of Pisa and AquaPLAN Project Coordinator, describes the central challenge as translating the substantial evidence that artificial light at night affects marine organisms and ecological processes into approaches that identify where ecosystems are most at risk, bringing together ecological knowledge and monitoring to provide a stronger basis for assessment and mitigation.

The authors also point to practical remedies, particularly for the tourist hotspots that dominate the list of most impacted regions. Authorities in those areas could explore meaningful changes to lighting infrastructure, including shielding fixtures to direct light downward, dimming or switching to part-night lighting schemes, and manipulating the wavelength composition of coastal lighting to reduce how far it penetrates into the sea, since blue-rich white light travels furthest through clear water. They further suggest designating dark spaces on and around islands, offering visitors an alternative experience to seasides ringed by artificial illumination. The researchers hope the methodology can be applied globally, and with the Marine Strategy Framework Directive currently under review, they argue the moment is ripe for light pollution to finally be written into European marine law with the same seriousness as noise, nutrients and chemical contaminants.

Subject of Research: A risk assessment framework for artificial light at night pollution in European marine waters

Article Title: Study highlights the European waters at greatest risk of harmful light pollution

Article References: Study highlights the European waters at greatest risk of harmful light pollution. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: light pollution, artificial light at night, marine conservation, Adriatic Sea, Baltic Sea, Mediterranean Sea, Marine Strategy Framework Directive, Good Environmental Status, AquaPLAN, water clarity, coastal ecosystems, University of Plymouth

The underlying chemistry is elegant. Seawater’s capacity to store carbon dioxide is governed by its total alkalinity, essentially the charge balance of carbonate and bicarbonate ions dissolved in it. When alkaline minerals such as olivine, limestone, quicklime, hydrated lime, steel slag or magnesium hydroxide dissolve in seawater, they shift the carbonate equilibrium: carbon dioxide is converted into bicarbonate and carbonate ions, lowering the partial pressure of CO2 at the sea surface and drawing more of the gas in from the atmosphere. Because the added alkalinity is conservative, meaning it persists in the water until consumed by other reactions, the stored carbon can remain out of the atmosphere for tens of thousands of years. This durability is what makes OAE attractive compared with biological approaches such as tree planting, where stored carbon can be released by a single fire.

Yet the authors argue that the field’s obsession with gigatonne-scale potential has distorted research priorities and public expectations. Instead, they propose a portfolio approach: many different OAE pathways, each matched to the local environment where it makes sense. Spreading crushed olivine on sandy beaches might suit one coastline; discharging alkalinity from wastewater treatment plants or desalination facilities might suit another; electrochemical methods that split seawater or accelerate carbonate dissolution on ships could serve shipping lanes; and adding alkaline minerals to organic-rich sediments, as experiments in the Baltic Sea suggest, could tap into benthic weathering processes. The diversity of pathways, the team writes, favours implementation across heterogeneous coastal environments, with upscaling achieved through widespread bottom-up adoption rather than centralized rollout.

A central claim of the Perspective is that the intended increase in seawater bicarbonate and carbonate shows no tendency to be inherently harmful within plausible limits. This is a striking statement, because the ocean is already suffering from the opposite problem: acidification. By raising alkalinity, OAE would partially reverse the pH decline that threatens corals, shellfish and calcifying plankton. Indeed, historical precedent exists. Lime has been used in aquaculture ponds for decades to manage pH, control pests such as starfish, and improve conditions for farmed shellfish and abalone, providing a long, largely overlooked record of alkalinity addition to coastal waters.

But harmless bicarbonate is not the whole story. The authors emphasize that collateral perturbations tend to drive the real environmental risk. Dissolving certain minerals can cause transient pH and CO2 excursions in the immediate vicinity of deployment. Mineral powders add suspended solids that can smother or abrade organisms. Some alkaline materials, notably steel slag and olivine, release trace metals such as nickel, chromium and copper, and several recent experiments have shown that these can influence plankton communities in pathway-specific ways. Land-based life-cycle impacts matter too: mining, grinding, transporting and dispersing minerals consumes energy and generates emissions, and life-cycle assessments show that a poorly designed OAE operation could erode or even negate its own carbon benefit. Environmental assessment, the team argues, should therefore focus on these pathway-specific local effects rather than on the added carbonate chemistry itself.

One of the most technically intriguing sections of the paper concerns sediments. Because most practical OAE deployments will occur near heterogeneous coastal sediments, their effectiveness will depend heavily on what happens at the seafloor. Sediments are not inert. They host natural alkalinity production through carbonate dissolution, silicate weathering, sulfate reduction and pyrite burial. Added alkaline minerals can interact with these processes in complicated ways: secondary minerals may precipitate and consume the very alkalinity that was added, a phenomenon known as runaway carbonate precipitation that laboratory studies have shown can be triggered when aragonite supersaturation exceeds critical thresholds. Conversely, alkaline additions may stimulate natural benthic weathering, amplifying the carbon removal beyond what the added mineral alone would deliver. There is also an additionality problem: anthropogenic alkalinity can suppress natural alkalinity-generating processes, so the net removal is smaller than the gross addition. Recent work on anthropogenic seafloor disturbances, such as bottom trawling, has even revealed that alkalinity destruction in disturbed sediments generates hidden CO2 emissions, underscoring how sensitive the coastal alkalinity budget is.

Verifying that a local OAE project actually removed the carbon it claims is perhaps the hardest problem of all. The added alkalinity draws down atmospheric CO2 only gradually, as air-sea equilibration takes months to years and depends on wind, temperature and mixing. Meanwhile, the ocean’s background carbonate chemistry varies enormously with season, currents and biological activity. The authors call for integrated, site-specific observation programs and high-resolution models that can distinguish a project-scale carbon removal signal from this natural variability and quantify uncertainty transparently. Nested coastal models, such as one recently developed for Halifax Harbour, illustrate the kind of local simulation that will be needed. Emerging carbon-removal registries and the first OAE credits have already highlighted how contested verification methodologies remain, and the paper argues that accounting rules must be locally grounded and openly documented to support trust.

Governance is the third pillar of the rethink. The authors argue that global geoengineering frameworks, centred on the London Convention and Protocol and the United Nations Convention on the Law of the Sea, are poorly suited to regulating thousands of small coastal deployments. Instead, they envision locally grounded regulation, community co-design and transparent carbon accounting, with projects shaped by the governments, Indigenous communities, aquaculturists and coastal residents who will live alongside them. Social science research shows that public acceptance hinges on exactly this kind of local involvement; surveys and scenario studies across several countries indicate that communities evaluate marine carbon removal not only on environmental risk but on procedural fairness, economic benefit and who controls the technology. The authors also stress humility: research suggests OAE could contribute to climate mitigation, but major uncertainties persist, and rigorous assessment must continue as deployments grow.

The practical vision sketched in the Perspective is, notably, consistent with what is already happening in the real world. Early commercial deployments have been small, coastal and locally negotiated, from shoreline mineral dispersal trials to ship-based experiments in the North Atlantic, and buyers have purchased modest volumes of removal credits rather than betting on gigatonne promises. Whether this bottom-up mosaic can deliver meaningful climate impact remains an open question, and the authors are careful not to overpromise. But their message is clear: the future of ocean alkalinity enhancement will be written not in one sweeping global treaty or one planetary intervention, but in hundreds of carefully monitored, environmentally responsible, demonstrably carbon-negative projects, each designed for the particular stretch of coast where it operates. For a field that has oscillated between utopian hype and reflexive dismissal, that shift from planetary dream to local practice may be the most important recalibration yet.

Subject of Research: Ocean alkalinity enhancement as a localized marine carbon dioxide removal strategy

Article Title: Rethinking ocean alkalinity enhancement

Article References: Rethinking ocean alkalinity enhancement. (n.d.). https://doi.org/10.1038/s43017-026-00828-5

Image Credits: AI Generated

DOI: 10.1038/s43017-026-00828-5

Keywords: ocean alkalinity enhancement, carbon dioxide removal, marine biogeochemistry, coastal ecosystems, enhanced weathering, carbon verification, ocean acidification, sediment chemistry, climate governance, geoengineering, carbon markets, marine carbon dioxide removal

The numbers behind the review are striking. Mangroves can hold up to 1,023 megagrams of carbon per hectare below ground, supported by anoxic, sulfate-reducing sediments and vertical accretion rates of 3 to 10 millimetres per year. Salt marshes sequester between 150 and 250 grams of carbon per square metre annually, while seagrass meadows bury 30 to 218 grams per square metre each year. Per unit area, these figures rival or exceed the sequestration rates of tropical rainforests, and salt marshes have been reported to store up to ten times more carbon per hectare than many terrestrial ecosystems. Because roughly half of all photosynthesis on Earth occurs in the ocean, the marine carbon cycle exerts a profound influence on atmospheric chemistry, and vegetated coastal habitats sit at the sharp end of that cycle.

The secret to mangrove carbon storage lies largely underground. Between 50 and 70 percent of the carbon in a mangrove forest resides in roots and soils, where prop roots, pneumatophores and fine root networks continuously deliver organic matter to the sediment. Waterlogged, oxygen-poor conditions suppress aerobic decomposition, forcing microbes down slower metabolic pathways such as fermentation and sulfate reduction. As a result, organic matter in mangrove soils breaks down three to ten times more slowly than in upland soils. The leaves and woody tissue of mangroves add another layer of defence, containing high concentrations of lignin, tannins and other polyphenolic compounds that resist microbial attack, extending the residence time of carbon in the sediment for centuries or even millennia.

Physical processes reinforce the biological ones. Dense canopies and root mats slow water flow, trapping fine mineral and organic particles delivered by rivers, tides and waves. This promotes vertical accretion, allowing mangroves in sediment-rich regions to accumulate surface elevation at rates exceeding 10 millimetres per year, which helps them keep pace with moderate sea-level rise while continuously burying carbon. Salt marshes operate on similar principles, trapping suspended sediments and building elevation under favourable tidal conditions. Seagrass meadows, descended from land plants that returned to the sea roughly 100 million years ago, stabilise sediments with dense root and rhizome mats, and global syntheses indicate they can store roughly twice as much carbon per hectare as terrestrial forests. Nutrient supply through their roots allows seagrasses to keep accumulating carbon even in otherwise nutrient-poor waters.

Microbes and algae add further dimensions to the story. The review highlights the microbial carbon pump, a process by which marine bacteria convert labile organic matter into refractory dissolved organic carbon that resists degradation and persists in the ocean for long periods. Alongside the biological pump, which transports roughly 10 to 15 percent of ocean primary production into the deep sea, and microbially induced carbonate precipitation, these mechanisms extend carbon storage far beyond the coastal zone. Macroalgae contribute as well, with an estimated 90 percent of algal carbon sequestration exported to the deep sea and the remainder buried in coastal sediments. Microalgae, which fix carbon dioxide at rates up to ten times more efficient per unit of solar energy than terrestrial plants, are attracting attention as candidates for engineered carbon removal.

Yet the review is equally clear about the fragility of these systems. Disturbance can flip a blue carbon sink into a carbon source with alarming speed. Converting mangrove forests to aquaculture ponds can release carbon at rates up to 50 times higher than the sequestration achieved by intact forests, while deforestation and hydrological alteration raise emissions to levels 10 to 40 times above normal sequestration. Drainage and aeration of organic-rich soils accelerate decomposition, and sediment erosion exposes long-buried carbon to oxidation. Methane generation under shifting hydrological regimes adds another greenhouse gas pathway. The authors also flag bioturbation as a double-edged factor: crabs remove an average of 87 percent of daily mangrove litter fall in some Thai forests, and burrowing animals in marshes and seagrass beds alter sediment mixing, burial depth and porewater exchange in ways that can either aid or undermine carbon retention.

Environmental drivers complicate the picture further. Moderate sea-level rise can actually enhance carbon burial by encouraging sediment trapping and peat formation, but rapid rise can drown marshes and mangroves, releasing stored carbon and, in some conditions, promoting methane and nitrous oxide emissions. Elevated temperatures accelerate decomposition of tropical wetland soils, stronger storms erode seagrass meadows and their carbon reserves, and Mediterranean droughts have reduced primary production in Posidonia oceanica meadows. Hydrology matters enormously: tidal connection in mangroves raises sediment deposition from less than 2 millimetres per year in restricted systems to more than 10 millimetres per year in open tidal habitats, and carbon accumulation in salt marshes correlates strongly with tidal amplitude. Nutrients cut both ways, since moderate nitrogen and phosphorus inputs stimulate productivity while excessive loading from agriculture and wastewater drives algal blooms, reduces water clarity and accelerates greenhouse gas emissions.

The pollution control function of blue carbon ecosystems is one of the review’s most intriguing threads. Mangrove and salt marsh root systems slow water flow and promote deposition of suspended particles, immobilising heavy metals such as lead, cadmium and zinc, along with hydrocarbons and persistent organic pollutants, in anoxic soils. Seagrass canopies trap fine particles and microplastics, reducing their transport into coastal waters, while plant uptake and microbial denitrification remove excess nitrogen and improve water quality. Mangrove sediments have even been identified as major sinks for plastic burial. However, the authors caution that accumulating plastics impose physical stress on organisms, risk ingestion by invertebrates and fish, and may alter sediment structure and microbial activity in ways that could affect organic carbon burial and greenhouse gas fluxes, making the interaction between pollution and carbon storage a priority research area.

Restoration offers genuine grounds for optimism. Meta-analyses and long-term field studies indicate that restored mangroves, salt marshes and seagrass beds can recover 50 to 90 percent of depleted carbon stocks over several decades, with some planted mangroves regaining significant portions of ecosystem carbon in under 20 years. Restored seagrass meadows have achieved carbon accumulation rates of roughly 20 to 40 grams per square metre per year within a decade, and managed realignment of salt marshes has produced rapid carbon accumulation in its early years. Measurement techniques are advancing in parallel, with lidar remote sensing enabling precise biomass estimates in inaccessible terrain, sediment coring paired with radiometric dating revealing long-term storage, and GIS-based carbon budgeting scaling local measurements to regional estimates.

The policy implications are substantial. Mangroves alone are estimated to capture up to 42 million tons of carbon annually worldwide, and blue carbon offsetting is emerging as a mechanism for channelling finance into coastal conservation, with co-benefits spanning storm protection, fisheries support and biodiversity. The authors argue that realising this potential requires marine protected areas, hydrological restoration, catchment-level management of nutrient inputs, standardised monitoring protocols and integration of blue carbon into national climate strategies and carbon markets. The IPCC’s Sixth Assessment Report recognises ecosystem restoration as a significant natural option for boosting carbon burial and coastal resilience. As the review concludes, protecting intact mangroves, marshes and meadows is not merely a carbon accounting exercise; it is an investment in living infrastructure that filters pollutants, buffers storms and quietly performs one of the most valuable services on the planet, one gram of buried carbon at a time.

Subject of Research: Blue carbon sequestration mechanisms and pollution control in coastal ecosystems for climate change mitigation

Article Title: Mechanisms, processes, and implications of blue carbon sequestration and pollution control for climate change mitigation

Article References: Dinakarkumar, Y., Selvam, M. M., Inayathullah, N., Pavithra, K. S., Mallikarjuna, H. N., Indhusuvitha, S., Jebacani, M. J., Romauld, S. I., & Muthezhilan, R. (2026). Mechanisms, processes, and implications of blue carbon sequestration and pollution control for climate change mitigation. Discover Oceans, 3(1), Article 5. https://doi.org/10.1007/s44289-026-00118-4

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00118-4

Keywords: blue carbon, mangroves, salt marshes, seagrass meadows, carbon sequestration, climate change mitigation, coastal ecosystems, sediment carbon burial, pollution control, sea-level rise, ecosystem restoration, microbial carbon pump

Researchers led by Cecilia Martin of Red Sea Global tagged 96 mature Avicennia marina trees across 12 sites spanning the northern Saudi Red Sea coastline. On each tree, three permanent terminal branches were marked and monitored monthly from August 2021 to October 2022, with the team counting bud clusters, flowers and propagules at every visit. The trees, averaging just 2.2 meters in height, reflect the naturally dwarfed growth habit that characterizes mangroves in this nutrient-poor, freshwater-starved region, where a one-meter tree is already considered reproductively mature.

The monitoring revealed a striking seasonal choreography. Buds and flowers increased in abundance during the hot summer months and declined through winter, while propagules followed the exact opposite pattern, peaking when temperatures fell. Using Generalized Additive Models, the team confirmed that these patterns were statistically significant rather than random fluctuations. Cross-correlation analysis showed that rising air temperatures prompted bud and flower production with a lag of about one month, while falling temperatures triggered propagule formation with a lag of zero to one month. Solar radiation also played a role, with buds and flowers responding positively to increased irradiation after a three-month delay, and propagules showing a negative correlation with a two-month lag.

Perhaps most surprising was what did not matter. Precipitation showed no significant correlation with any reproductive phase, and sea surface salinity showed no link to propagule abundance. In a hyper-arid environment where annual rainfall is less than 50 millimeters and fell almost entirely in just two months of the study period, this makes ecological sense. The species’ renowned salt tolerance appears to render sea surface salinity irrelevant to its reproductive timing, although the authors caution that soil pore-water salinity, which can reach far higher levels during hot, dry summers when evaporation concentrates salts in the sediment, may still suppress propagule development and germination.

When the team normalized propagule counts across sites to remove the influence of naturally more productive forests, a second, previously hidden reproductive season emerged. Beyond the dominant winter season running from December to April and peaking in February, a secondary flush of propagule production occurs at the end of summer, around August to October. Cluster analysis then revealed a clear latitudinal gradient: the three northernmost sites peaked around September, the five central sites peaked from February to March, and the three southernmost sites peaked earliest, from December to January. This south-to-north progression mirrors patterns documented across Australia, New Zealand and Papua New Guinea, where mangrove reproduction is consistently delayed at higher, cooler latitudes.

The ecological logic behind this temperature-driven schedule is compelling. Studies of the related species Avicennia germinans have shown that high temperatures inhibit propagule rooting and germination, suggesting that mangroves maximize recruitment success by releasing their offspring during cooler months. In the northern Red Sea, where winter temperatures can drop low enough to threaten less hardy species, Avicennia marina’s well-documented cold tolerance allows it to exploit this window. The correlation between propagule production and seawater level further supports the idea that higher water levels aid the floating dispersal mechanism by which mangrove propagules spread.

These findings arrive at a critical moment. Saudi Arabia has made mangrove restoration a centerpiece of its Vision 2030 strategy and the Saudi Green Initiative, with Red Sea Global committing to plant or enhance 50 million mangrove trees in the region. Until now, propagule harvesting has been based on local observations at a handful of forests. The new study provides the region-wide, quantitative foundation needed to plan harvesting operations scientifically, identifying exactly where and when propagules can be collected at their peak abundance across the entire study area.

The latitudinal gradient offers a practical advantage: by targeting different forests during their respective peak months, harvesters can spread collection across multiple months of the year, reducing pressure on any single stand while maximizing the genetic diversity of collected propagules. To safeguard natural regeneration, the researchers applied a Maximum Sustainable Yield framework, capping harvests at 50 percent of mature propagules per tree. Under this framework, the 12 assessed forests, which together represent roughly one third of the region’s total mangrove area of 2,400 to 2,700 hectares, could sustainably supply around 680,000 propagules per year during peak season, or an estimated 2 million across the full region. Including shoulder months, availability could reach approximately 4 million propagules annually, meaning the 50-million-tree goal could theoretically be met in about 13 years, though the authors stress this idealized scenario ignores accessibility constraints and germination failures.

The dual-season reproductive pattern carries an additional operational bonus for nurseries. Avicennia marina propagules germinate within days of harvesting and seedlings are typically grown for six to eight months before reaching the roughly 50-centimeter size suitable for outplanting. Propagules collected in December would therefore be ready to leave the nursery just as the second propagation season begins in August, allowing nursery space to be reused twice a year and minimizing the physical footprint of propagation operations.

The study also sounds a note of caution for a warming world. Rising temperatures could extend the flowering season at this northern range limit, potentially improving reproductive completion, yet the same warming is expected to impair propagule germination and early recruitment, which favor cooler conditions. Conversely, milder winters may boost seedling survival where cold damage currently constrains regeneration. These opposing feedbacks make the fate of range-edge mangrove populations genuinely uncertain. What is clear is that understanding the fine-grained, site-specific reproductive biology of these remarkable trees is no longer an academic luxury. As mangrove ecosystems worldwide continue to decline, losing roughly 3.4 percent of their extent between 1996 and 2020, the success of the restoration projects meant to reverse that trend will depend on precisely this kind of ground-truthed ecological knowledge, harvested one tagged branch at a time.

Subject of Research: Reproductive phenology of the grey mangrove Avicennia marina at its northwestern range limit in the northern Red Sea

Article Title: Understanding the reproductive phenology of Avicennia marina at its northwestern range in the Arabian Peninsula supports improved afforestation planning

Article References: Martin, C., Rossbach, S., Alansari, A., & El-Bana, M. (2026). Understanding the reproductive phenology of Avicennia marina at its northwestern range in the Arabian Peninsula supports improved afforestation planning. Discover Oceans, 3(1), Article 22. https://doi.org/10.1007/s44289-026-00135-3

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00135-3

Keywords: mangroves, Avicennia marina, Red Sea, phenology, propagules, afforestation, restoration, Saudi Arabia, hyper-arid climate, temperature, Maximum Sustainable Yield, coastal ecosystems

The study, published in the journal Global Biogeochemical Cycles, was led by John Harrison, the Edward R. Meyer Distinguished Professor in WSU’s School of the Environment. Harrison, who directs the Global Change and Watershed Biogeochemistry Laboratory, noted that while the ocean is vast, the contribution of land-based nutrients to coastal zones has been a subject of debate among oceanographers. The research aims to resolve this uncertainty by integrating data on what enters coastal waters from land with data on offshore marine sources. The findings suggest that the scientific community studying the coastal impacts of land-based nutrients has been correct in emphasizing the importance of these inputs.

Human activities introduce nitrogen and phosphorus into rivers and coastal waters through various pathways. These include fertilizer and manure runoff from agricultural lands, wastewater emissions from sewage systems, urban runoff from lawns and streets, and emissions from vehicles and power plants. The researchers developed a novel database that covers global sources of nitrogen, phosphorus, and silicon across both pre-industrial and contemporary time spans. This database allows for an evaluation of how land-based human activities have altered nutrient ratios and increased the potential for eutrophication, a condition that promotes excessive algae growth and degrades water quality.

One of the key findings of the study is that while natural marine sources remain the largest overall contributor of nutrients globally, land-based sources constitute the majority of nutrients for more than half of the world’s coastlines. This indicates that in a substantial number of coastal regions, the balance of nutrient input is dominated by terrestrial processes rather than open-ocean dynamics. The study distinguishes between different types of nutrients, noting that the impact of human activity varies significantly depending on the specific element being measured.

Regarding nitrogen, the research found that human activities add more nitrogen than all natural sources in approximately a quarter of the planet’s coastal waterways. This human-driven excess is also evident in a fifth of the Large Marine Ecosystems, which are the large ocean areas extending outward from the coasts. For phosphorus, the human contribution exceeds natural sources in 11% of coastal waterways. These figures underscore the localized but significant nature of nutrient pollution, where specific regions experience disproportionate impacts due to concentrated human activity and land use practices.

The influence of human activity on silicon presents a contrasting trend. Rather than increasing levels, human activities tend to lower silicon levels in coastal waters. A primary mechanism for this reduction is the construction of river dams, which block the natural flow of silicon from land to the coast. Silicon is essential for certain marine organisms, such as diatoms, and its reduction can have cascading effects on marine food webs. This finding highlights that nutrient pollution is not a uniform issue; while some nutrients are being added in excess, others are being depleted, both of which can disrupt the delicate balance required for healthy marine ecosystems.

The study identifies specific geographic areas of greatest concern, including the Gulf of Mexico and the coastlines surrounding Europe and Asia. These regions are characterized by high levels of human impact and significant nutrient loading. By pinpointing these areas, the research provides a framework for prioritizing management efforts. Harrison emphasized that understanding where nutrient inputs are most critical is essential for effective resource allocation. The study serves as a first step in creating a framework to manage coastal zones efficiently, ensuring that mitigation strategies are directed where they will have the most substantial impact.

Several strategies could be adopted to reduce the nutrient load entering rivers and coastal waters. These range from implementing advanced technology in wastewater treatment plants to improving fertilizer management practices and adopting no-till farming methods. The study identifies areas where the health of coastal waters could be directly improved by changes in human contributions. Harrison noted that there are stretches of coastline globally where a significant increase in nutrient inputs would push the ecosystem into a danger zone, while a significant decrease would remove it from that zone. This distinction is crucial for policymakers and managers, as it identifies locations where intervention can yield clear benefits versus areas where high natural background nutrient loads may complicate management efforts.

The research underscores the importance of a holistic approach to coastal management. By integrating data on land, sea, and human inputs, the study provides a more complete picture of nutrient dynamics than previous global assessments. The findings suggest that while the challenge is significant, targeted interventions can make a meaningful difference. As coastal populations grow and economic activities intensify, the need for precise data to guide management decisions becomes increasingly urgent. The study offers a valuable tool for scientists, policymakers, and stakeholders seeking to protect the health and productivity of the world’s coastal waters.

Subject of Research: Marine Science

Article Title: Study maps where humans are driving harmful nutrient levels along coasts

Article References: Study maps where humans are driving harmful nutrient levels along coasts. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: coastal ecosystems, nutrient pollution, nitrogen, phosphorus, silicon, eutrophication, Washington State University, Global Biogeochemical Cycles, maps, humans, driving, harmful

The scale of the problem tracks the scale of the industry. Global production of rare earth elements roughly tripled between 2000 and 2020, with China historically supplying more than 80 percent of the world total, and in some years over 90 percent of mined and processed material. Extraction and refining generate tailings and effluents rich in dissolved light rare earths such as lanthanum, cerium, and neodymium, and heavy rare earths such as dysprosium and erbium. Mining hotspots in southern China and Myanmar have released these elements into river systems that ultimately discharge into coastal seas. Beyond mining, electronic waste dismantling, wastewater treatment plant effluents, medical imaging residues from gadolinium-based MRI contrast agents, and even rare earth enriched fertilizers used in Chinese and Southeast Asian agriculture all funnel additional metal into rivers, estuaries, and ultimately the ocean.

For decades, regulators essentially ignored these elements. Unlike mercury, cadmium, or lead, rare earths were considered environmentally immobile and biologically benign, so they were rarely included in chemical safety assessments and almost never monitored in aquatic systems. That assumption began to collapse in the late 2000s, when advances in inductively coupled plasma mass spectrometry made it possible to detect rare earths at environmentally relevant concentrations in surface waters, sediments, and biota. The measurements revealed a global footprint: elevated concentrations near industrialized coastlines, in estuaries receiving industrial runoff, and in sediments influenced by atmospheric deposition. Yet despite this growing evidence base, rare earths still lack internationally harmonized water quality guidelines, chronic exposure criteria, or priority pollutant status under frameworks such as the EU Water Framework Directive, the U.S. Clean Water Act, MARPOL, or the OSPAR Convention. Only Canada and China have begun to incorporate preliminary reference values, and those efforts remain limited.

The chemistry of rare earths in seawater is distinctive and helps explain their biological behavior. They occur predominantly in the trivalent state and bind strongly to carbonate ligands and organic colloids, producing speciation patterns quite different from those of transition metals. Light rare earths tend to be more abundant and more bioavailable near anthropogenic sources, while heavy rare earths form more stable complexes with organic matter. Environmental factors such as pH, salinity, redox conditions, and competing ions profoundly modulate which chemical forms are present and therefore how much metal organisms actually take up. Sediments act as a major reservoir, with reported concentrations ranging from under one microgram per gram in some Red Sea coastal sediments to more than 73 micrograms per gram in Chinese sediments, and biogeochemical processes can remobilize this pool back into porewater where benthic animals encounter it.

Marine invertebrates sit squarely in the exposure pathway. Their permeable epithelial surfaces, filter feeding and particle ingestion strategies, and reliance on ion regulated physiology make them unusually sensitive to metal contamination, and bioaccumulation has now been documented in bivalves, crustaceans, echinoderms, polychaetes, and corals. The blue mussel Mytilus edulis, with its prodigious filtration capacity, shows a total rare earth and yttrium concentration of about 2 micrograms per gram, while the Mediterranean mussel accumulates light rare earths such as lanthanum and cerium at levels far exceeding heavy rare earths like ytterbium and lutetium. Corals incorporate dissolved rare earths directly into their aragonitic skeletons, with skeletal patterns closely mirroring surrounding seawater, which makes them useful geochemical archives of contamination.

The toxicological evidence is striking in its specificity. Mussels exposed to lanthanum at concentrations of 100 micrograms per liter or more developed marked oxidative stress, reduced metabolic activity, and necrosis of digestive gland tubules. Gadolinium exposure beginning at just 30 micrograms per liter disrupted redox homeostasis, increased lipid peroxidation, and depleted the ratio of reduced to oxidized glutathione, a classic signature of overwhelmed antioxidant defenses. Oyster larvae proved even more vulnerable, with concentration dependent malformations appearing at EC50 values as low as 6.7 micrograms per liter for lanthanum. In sea urchins, the review highlights pronounced inter element variability: in Sphaerechinus granularis, the EC50 for abnormal development ranged from 8 micrograms per liter for lanthanum to 874 micrograms per liter for gadolinium, while the related species Arbacia lixula showed a completely different sensitivity ranking, underscoring that toxicity cannot be generalized across elements or species. Copepods exposed to nine different rare earths suffered concentration dependent mortality, immobilization, and suppressed naupliar molting.

The mechanistic story ties these observations together. Rare earth ions chemically mimic calcium, competing with Ca2+ for binding sites on membrane proteins, channels, and pumps, thereby disrupting signal transduction, neurotransmission, ciliary movement, and, critically, the biomineralization pathways that build shells and skeletons. Because early embryos have highly permeable membranes and depend heavily on calcium mediated signaling, they are especially susceptible, which explains the skeletal malformations and delayed gastrulation seen in echinoderm larvae. Independently, rare earths destabilize cellular redox balance, generating reactive oxygen species that damage lipids, proteins, and DNA, while also modulating key enzymes including Na+/K+-ATPase, superoxide dismutase, catalase, and glutathione peroxidase. Although rare earths do not biomagnify as strongly as classic heavy metals, they are transferred through food webs from algae to grazers and from sediments to benthic consumers, and repeated dietary exposure can compound physiological stress over time.

Against this backdrop, the review’s most hopeful finding concerns brown macroalgae. The cell walls of species such as Sargassum, Turbinaria, Fucus, and Undaria are dominated by alginate and fucoidan, polysaccharides studded with carboxyl and sulfate groups that chelate trivalent rare earth cations with exceptional affinity. The dominant binding mechanisms include ion exchange, complexation with carboxyl groups, electrostatic interaction with sulfated moieties, and surface adsorption followed by diffusion into the cell wall matrix. Dried, non living biomass is particularly attractive for remediation because it requires no nutrients, tolerates metal loads that would kill living tissue, and can be packed into engineered systems. Reported maximum sorption capacities reach approximately 150,000 micrograms per gram in the best performing species, substantially exceeding activated carbon and many synthetic ion exchange resins, and Sargassum filipendula maintains its performance under the high salinity conditions that cripple conventional adsorbents.

The practical vision is a tiered, nature based defense of coastal waters. Non living algal biomass could be deployed in packed bed filters, cartridge systems, shoreline interception modules, or estuarine polishing units to strip dissolved rare earths from mining runoff, industrial discharges, and sediment porewaters before the metal disperses to vulnerable communities. Because biosorption is partially reversible, accumulated rare earths could even be desorbed and recovered, turning a pollution problem into a circular economy opportunity. Living macroalgae, meanwhile, show bioconcentration factors approaching 944 in Fucus vesiculosus under multi element exposure, making them valuable early warning biomonitors even though their own oxidative stress responses limit their use as direct remediation agents. The review proposes integrating these biosorption systems with sentinel species monitoring, risk assessment frameworks, and coastal management, from marine protected areas to estuarine buffer zones.

Substantial gaps remain before any of this becomes routine practice. Chronic toxicity thresholds for marine organisms are essentially undefined, the interactions between rare earths and co-occurring stressors such as warming, acidification, and hypoxia are unexplored, and the scalability of macroalgal biosorption under realistic field conditions has never been tested at pilot scale. Speciation, the master variable governing uptake, remains poorly characterized in natural seawater, and standardized toxicity testing protocols do not yet exist. But the direction of travel is unmistakable: as demand for rare earths accelerates with the electrification of the global economy, so too will their release into the sea. The review’s authors argue that timely, integrative research combining ecotoxicology, marine chemistry, and environmental engineering is now essential to safeguard marine biodiversity, and that seaweed, one of the ocean’s most humble inhabitants, may prove to be one of its most effective protectors.

Subject of Research: Rare earth element contamination of marine ecosystems and brown macroalgal biosorption as a mitigation strategy

Article Title: A review of rare earth elements as emerging marine pollutants and their impacts on invertebrates and macroalgae mediated biosorption

Article References: Mohammadpour, S., & Mohammadpour, H. (2026). A review of rare earth elements as emerging marine pollutants and their impacts on invertebrates and macroalgae mediated biosorption. Discover Oceans, 3(1), Article 32. https://doi.org/10.1007/s44289-026-00146-0

Image Credits: AI Generated

DOI: 10.1007/s44289-026-00146-0

Keywords: rare earth elements, marine pollution, emerging contaminants, marine invertebrates, ecotoxicology, biosorption, brown macroalgae, oxidative stress, calcification, coastal ecosystems, bioremediation, heavy metals