Marine Environmental Research[JOURNAL]
Sun
200 papers
Climate-driven restructuring of phytoplankton productivity and community composition in the south-eastern black sea: Insights from seasonal CO-Temperature manipulation experiments.
Ağırbaş E, Dizman S, Şahin A … +5 more , Gedik K, Fidan D, Mutlu T, Yener Helvacı M, Feyzioğlu AM
Mar Environ Res · 2026 Jun · PMID 41934932 · Publisher ↗
Semi-enclosed marine systems with low buffering capacity, such as the Black Sea, are expected to experience amplified impacts of ocean acidification and warming, yet experimental evidence on their combined short-term eff...
Semi-enclosed marine systems with low buffering capacity, such as the Black Sea, are expected to experience amplified impacts of ocean acidification and warming, yet experimental evidence on their combined short-term effects on natural phytoplankton assemblages remains limited. Here, we present a seasonally resolved one-year study (four experiments conducted between 2022 and 2023) based on 48 h short-term microcosm incubation experiments using natural phytoplankton communities collected from coastal and offshore stations in the south-eastern Black Sea. CO concentrations (360, 600, and 760 ppm) and temperature (ambient and +3 °C) were manipulated to examine short-term physiological and compositional responses under projected climate scenarios. We hypothesised that CO and warming would exert both independent and interactive effects on short-term particulate organic carbon production (C uptake rates) and relative community composition, with responses varying seasonally and being most pronounced during summer stratification. Short-term particulate primary production increased by ∼22% and ∼36% at 600 and 760 ppm CO, respectively (p<0.05), while warming provided an additional 14-22% enhancement depending on season, with significant CO × temperature interaction terms detected for total production (two-way ANOVA, p<0.05), indicating synergistic CO-temperature effects. Warming and moderate CO enrichment were associated with increased relative contributions of nano- and picophytoplankton (by ∼6-10%), whereas high CO reduced the warming-driven shift toward smaller cells by maintaining microphytoplankton contributions ∼10-15% higher than in the warming-only treatment. Carbonate chemistry responded strongly to CO manipulation, with pH declining from in-situ values of 8.09-8.21 to 7.06-7.52 during incubations and minor reductions in total alkalinity, reflecting the weak buffering capacity of the system. Pigment composition and microscopy indicated short-term increases in dinoflagellate relative abundance (∼12-18%) and concurrent declines in diatom markers, accompanied by accelerated nitrate depletion and reduced nitrogen-to-phosphorus (N:P) ratios, consistent with enhanced nitrogen limitation. Overall, these findings demonstrate pronounced short-term sensitivity of natural phytoplankton assemblages in the south-eastern Black Sea to combined CO and warming under controlled incubation conditions. Because these results derive from 48 h microcosm experiments, they represent short-term physiological and compositional responses rather than direct evidence of long-term ecosystem restructuring, yet the observed patterns suggest potential implications for trophic efficiency, harmful algal bloom development, and carbon cycling in this low-buffer, stratified basin under future climate forcing.
Environmental transformation and ecological implications of surface and subsurface microplastics in marine environments.
Yadav S, Rout S, Pulhani V … +1 more , Kumar AV
Mar Environ Res · 2026 Jun · PMID 41934931 · Publisher ↗
Nearly 67% of plastics entering the oceans remain unaccounted for a phenomenon termed the "missing plastic paradox," likely driven by vertical transport of suspended plastics to deeper waters. Yet, the transformation and...
Nearly 67% of plastics entering the oceans remain unaccounted for a phenomenon termed the "missing plastic paradox," likely driven by vertical transport of suspended plastics to deeper waters. Yet, the transformation and contaminant-binding potential of these submerged microplastics (MPs) remain poorly understood. This study explores how depth influences the physicochemical and biological evolution of six common polymer types (HDPE, LDPE, PP, PS, PET, and OTHERs) during five months of exposure in a coastal marine system. FTIR, contact angle, and surface energy analyses revealed significant weathering and oxidation in all polymers, with surface MPs exhibiting greater hydrophilicity and polar surface energy due to intense UV-induced oxidative stress. Biofilm characterization showed distinct depth-related patterns: compact, autotroph-dominated biofilms at the surface and thicker, EPS-rich, heterotrophic biofilms at depth. These biological modifications substantially increased the sorption capacity of MPs for metals. Batch sorption experiments demonstrated that Pb and Cd distribution coefficients (K) rose significantly in subsurface MPs compared to pristine MPs (about 600 fold in case of Pb uptake by LDPE). The results highlight the pivotal role of depth-dependent aging and biofilm development in enhancing contaminant affinity, thereby influencing the vertical redistribution, ecological risks, and long-term fate of MPs in marine environments.
Dual challenges of eutrophication and stoichiometric imbalance: Implications for coordinated nutrient management in the jiulong river estuary.
Xiang T, Wei Q, Tian Y … +6 more , Huang F, Wang F, Xu W, Liu L, Yang S, Cao W
Mar Environ Res · 2026 Jun · PMID 41934930 · Publisher ↗
Subtropical estuaries are profoundly impacted by intensive anthropogenic activities, making the inputs of terrestrial nutrients a critical focus for estuarine ecosystem management. Here, we conducted a three-year, 12-sea...
Subtropical estuaries are profoundly impacted by intensive anthropogenic activities, making the inputs of terrestrial nutrients a critical focus for estuarine ecosystem management. Here, we conducted a three-year, 12-season investigation in the Jiulong River Estuary (JRE) to characterize spatiotemporal patterns in nutrient ratios and eutrophication and assess their associated environmental effects. The eutrophication index (EI) ranged from 0.32 to 386.83 (mean, 46.62 ± 73.10). EI decreased significantly along the salinity gradient (P < 0.05) and peaked in winter (P < 0.05). Across the three-year period, the indicator of coastal eutrophication potential of phosphorus (P-ICEP) remained negative, whereas N-ICEP ranged from -3.58 to 4.60 kg C/km/day and was generally higher in winter (P < 0.05). The DIN/DIP (N/P) ratio of terrestrial nutrient flux ranged from 42.89 to 277.01 (mean, 97.38 ± 61.30), while the N/P ratio in estuarine waters ranged from 7.76 to 1259.05 (mean, 114.86 ± 140.07), indicating persistent phosphorus (P) limitation. High riverine N/P inputs likely drove nutrient-ratio imbalances and eutrophication, increased the risk of red tide outbreaks, and accelerated P consumption. Therefore, ecosystem-based estuarine management should move toward the integrated regulation of nutrient fluxes, stoichiometric ratios, and ecological effects. We further propose the combined use of ICEP and EI as a management tool for the watershed-estuary continuum, leveraging their ability to identify eutrophication potential and ecological risk while helping prevent shifts in algal communities toward harmful bloom-forming species. We recommend coordinated land-to-sea control of both N and P loads and their ratios to enable integrated, ecosystem-based scientific management from watershed to estuary.
Hidden diversity of marine zooplankton under sea ice in the Okhotsk Sea: Insights from community and population analyses based on DNA metabarcoding.
Hirai J, Yamaguchi A, Katakura S
Mar Environ Res · 2026 Jun · PMID 41932184 · Publisher ↗
The Okhotsk Sea is a semi-closed marine area characterized by unique environments, including seasonal sea ice during winter, and is expected to harbor distinct zooplankton diversity. However, zooplankton beneath sea ice...
The Okhotsk Sea is a semi-closed marine area characterized by unique environments, including seasonal sea ice during winter, and is expected to harbor distinct zooplankton diversity. However, zooplankton beneath sea ice remain inadequately researched, primarily because of sampling and methodological challenges. In this study, we used the Okhotsk Tower and icebreakers Garinko II/III, typically used for sightseeing, to collect zooplankton samples during the sea-ice season off the coast of Mombetsu, Hokkaido, Japan. We used DNA metabarcoding of mitochondrial cytochrome oxidase subunit I (COI) and nuclear small ribosomal subunit (18S) genes to assess species- and population-level diversity. Metabarcoding analyses of both COI and 18S revealed clear shifts in zooplankton community composition based on operational taxonomic units (OTUs), which aligned with environmental differences in water temperature and chlorophyll concentration. BLAST searches indicated that 37.6% of COI and 21.5% of 18S OTUs shared <97% identity with known sequences, indicating potentially hidden species diversity or inadequate reference data in public databases. The dominant COI-identified taxa included Clione okhotensis, Neocalanus flemingeri, Pseudocalanus acuspes, and P. newmani, which were described or known to have distinct diversity in the Okhotsk Sea. For the other dominant species, namely Acartia longiremis, Eucalanus bungii, and Hybocodon prolifer, dominant haplotypes were not shared with other geographic regions based on amplicon sequence variants. Although diversity patterns are influenced by the ecological traits of zooplankton species, our metabarcoding approach effectively captured both species- and population-level diversity, thereby highlighting the presence of previously unrecognized zooplankton diversity beneath the sea ice of the Okhotsk Sea.
Robust gut microbiota as a key protective barrier for Ruditapes philippinarum survival following an extreme-rainfall disturbance.
Liu L, Liu L, Li A … +4 more , Liu Z, Xue S, Li J, Mao Y
Mar Environ Res · 2026 Jun · PMID 41932183 · Publisher ↗
Gut microbiota is critical for host health, yet its role in buffering filter-feeding bivalves against acute habitat disturbance remains poorly understood. Here, the Manila clam Ruditapes philippinarum was used as a model...
Gut microbiota is critical for host health, yet its role in buffering filter-feeding bivalves against acute habitat disturbance remains poorly understood. Here, the Manila clam Ruditapes philippinarum was used as a model to investigate how an extreme rainfall event reshaped microbial communities in the gut and surrounding habitat (water and sediment), with sampling conducted before and 10 and 30 days after the event. Extreme rainfall caused mass mortality and markedly disrupted host-associated microbiota. Surviving clams harbored gut microbiota with higher diversity and richness, enrichment of putatively beneficial taxa (e.g., Actinomycetota, Bacteroidota, Verrucomicrobiota, and Bacillus), reduced abundance of the opportunistic pathogen Vibrio, and increased network complexity and stability, accompanied by enrichment of functional potentials related to energy metabolism, signal transduction, and stress adaptation. Notably, gut community assembly shifted toward greater stochasticity, broader niche breadth, and reduced dispersal limitation during recovery, indicating a reassembly pattern that balances compositional stability with adaptive flexibility. Together, these results highlight gut microbiota robustness and assembly plasticity as key mechanisms linking extreme-rainfall disturbance to clam resilience, providing insights for microbiome-informed management to support sustainable bivalve aquaculture.
Temporal dynamics of crustacean zooplankton community structure and functional traits in a temperate island marine ecosystem: A case study of the adjacent waters of the Miaodao Archipelago, China.
Zhao J, Shi Y, Shan X … +3 more , Zou J, Wei C, Wang H
Mar Environ Res · 2026 Jun · PMID 41932182 · Publisher ↗
Understanding the dynamics of zooplankton community structure and functional traits is crucial for predicting the stability of the temperate island marine ecosystems. This study investigated the temporal dynamics of the...
Understanding the dynamics of zooplankton community structure and functional traits is crucial for predicting the stability of the temperate island marine ecosystems. This study investigated the temporal dynamics of the crustacean zooplankton community, including species composition, abundance, and functional traits in the adjacent waters of the Miaodao Archipelago from March to December 2021. Based on four key traits (body length, feeding strategy, trophic type, and reproductive strategy), the community was classified into five functional groups to analyze their responses to environmental changes. A total of 24 crustacean zooplankton species were identified, with the community dominated by Oithona similis, Acartia hongi, and Paracalanus parvus. The dominant functional traits included small body size (<1 mm), mixed feeding, omnivorous-herbivore, and free spawning. Each functional group exhibited distinct responses to environmental changes. For example, lower temperatures were associated with increased abundance of egg brooding species, while omnivorous-herbivorous species showed higher abundance in relation to high chlorophyll a concentrations. In addition, extreme weather events (continuous extreme rainfall) appeared to significantly impact both community structure and functional composition of crustacean zooplankton. This study provides a perspective for understanding the dynamics of crustacean zooplankton community functional structure in the temperate island marine ecosystems.
Behavioural, physiological, and biochemical responses of two species of scleractinian coral to butterflyfish predation.
Hsu TT, Hoey AS, Warren CR … +2 more , Marrable I, Figueira WF
Mar Environ Res · 2026 Jun · PMID 41926821 · Publisher ↗
The negative effects of coral loss on fish assemblages are well established, particularly for obligate corallivores. In contrast, the impacts of corallivorous fish on corals themselves have received less attention, thoug...
The negative effects of coral loss on fish assemblages are well established, particularly for obligate corallivores. In contrast, the impacts of corallivorous fish on corals themselves have received less attention, though chronic predation is expected to impose sublethal costs. This study examined how two scleractinian corals, Acropora samoensis and Pocillopora damicornis, responded to varying levels of predation by the polyp-feeding butterflyfish, Chaetodon rainfordi, in a 17-day tank experiment. We assessed the effects of predation on behaviour (polyp withdrawal), physiology (growth, ash-free dry weight, photosynthetic efficiency), and biochemistry (fatty acid content) of coral colonies; with fatty acid profiles further providing insight into energy balance (structural vs. storage lipids), trophic strategy, and coral health. The two species showed contrasting responses. A. samoensis withdrew most polyps even at low predation (88% withdrawn at 0.5 bites min colony), likely suppressing heterotrophy and leading to reduced growth, although other physiological and biochemical traits remained unaffected. In contrast, P. damicornis, a relatively heterotrophic species, maintained ∼71% of polyps extended under the same intensity, sustaining feeding but incurring greater tissue loss and declining health condition. Nevertheless, growth and ash-free dry weight were maintained, likely through mobilization of storage fatty acids derived from both autotrophic and heterotrophic sources. These results highlight the resilience of corals to chronic butterflyfish predation, as most colonies maintained positive growth even under relatively high per-colony bite rates. However, the observed energy trade-offs suggest potential consequences for reproduction and susceptibility to environmental stress, indicating that chronic predation by non-skeletal feeding corallivores may subtly shape coral performance and persistence.
Fishing trawlers drive the fine-scale daytime distribution of bottlenose dolphins at the Tiber River estuary (Western Mediterranean Sea).
Labriola MS, Parisi A, Marinchel N … +5 more , Rinalduzzi S, Turchi A, Giacomini G, Pace DS, Russo T
Mar Environ Res · 2026 Jun · PMID 41926820 · Publisher ↗
Fisheries can strongly alter marine ecosystem dynamics, influencing the ecology and behaviour of top predators such as cetaceans. At the Tiber River estuary (Tyrrhenian Sea, Western Mediterranean), bottlenose dolphins (T...
Fisheries can strongly alter marine ecosystem dynamics, influencing the ecology and behaviour of top predators such as cetaceans. At the Tiber River estuary (Tyrrhenian Sea, Western Mediterranean), bottlenose dolphins (Tursiops truncatus) frequently interact with bottom trawlers operating off the coast of Rome. We combined five years (2019-2023) of boat-based survey data with fishing data derived from the Vessel Monitoring System (VMS) to assess the influence of trawling activity on dolphin distribution. Spatial and temporal correlations between dolphin presence and fishing effort were analysed using multivariate analysis and overlap metrics. Dolphin occurrence was modelled relative to environmental and vessel-level predictors with generalized linear mixed-effects models (GLMMs), incorporating chlorophyll-a concentration (concurrent and lagged) as a proxy for productivity. In the area where sufficient survey effort was invested, dolphin presence was strongly associated with fishing hotspots, and dolphins shifted farther offshore on trawling days, indicating an ecological switch from nearshore natural resources to trawler-associated prey. Spatial overlap varied markedly among vessels, indicating preferences for certain trawlers. GLMMs identified specific vessels with a significant positive effect on dolphin occurrence, even after controlling for productivity. Catch analysis revealed these vessels landed higher amounts of European hake and common octopus, key dolphin prey species. Findings suggest dolphins exhibit flexible, and possibly socially acquired, foraging strategies in response to fisheries, with trawling acting as a strong driver of their distribution. While adaptive, such associations may reduce natural foraging, alter ecological dynamics, and pose conservation issues. This study provides a fine-scale perspective of fishery-driven behavioural change in dolphins and offers actionable insights for local management under EU marine biodiversity directives.
Mangrove species act as potential biofilters for legacy organochlorine pesticides: evidence from tissue-specific accumulation in the Zhangjiang Estuary.
Luo N, Fang T, Qian Y … +8 more , Wang L, Lin W, Song R, Li G, Wu F, Chen X, Lin M, Lin Y
Mar Environ Res · 2026 Jun · PMID 41926819 · Publisher ↗
Mangrove wetlands can act as potential biofilters and biomonitors for legacy organochlorine pesticides (OCPs), yet the species- and tissue-specific partitioning and retention of OCPs in mangrove systems remain poorly und...
Mangrove wetlands can act as potential biofilters and biomonitors for legacy organochlorine pesticides (OCPs), yet the species- and tissue-specific partitioning and retention of OCPs in mangrove systems remain poorly understood. Here, we quantified eleven OCPs (HCB, HCH isomers, and DDTs) in surface sediments and in roots, stems, and leaves of four dominant mangrove species (Kandelia obovata, Aegiceras corniculatum, Avicennia marina, and Sonneratia apetala) from the Zhangjiang Estuary, China, using solid-phase microextraction coupled with GC-MS/MS. Total OCP concentrations were relatively low in sediments (0.17-0.81 ng g dw; median 0.32), but substantially higher in mangrove tissues (0.05-7.50 ng g dw; median 0.83), with a tendency for higher tissue burdens in leaves. Diagnostic ratios suggest primarily historical DDT inputs under mixed aerobic-anaerobic degradation conditions, whereas HCH signatures are consistent with lindane-dominated sources superimposed on aged residues. BCFs revealed clear compound-, tissue-, and species-dependent enrichment. Overall, HCHs and HCB were more enriched than DDT-related residues, with δ-HCH showing the strongest accumulation (BCF up to 74.35), whereas selected DDT congeners could still be highly enriched (e.g., 4,4'-DDT, BCF up to 31.96). Leaves exhibited particularly strong enrichment in some species, exemplified by A. corniculatum (leaf HCB BCF = 17.60; leaf δ-HCH BCF = 74.35), while A. marina showed more pronounced enrichment of DDT-related residues (leaf 4,4'-DDT BCF = 31.96; root 4,4'-DDD BCF = 25.56). Among species, A. corniculatum had the highest overall accumulation capacity across tissues, suggesting the greatest phytoremediation potential, whereas other mangroves provided complementary, compound-specific retention functions. These results highlight mangroves as effective biofilters and useful biomonitors for legacy OCPs in subtropical estuaries.
Assessment of PAH-associated health risk and food safety in high-value fish species following one of the largest and most extensive oil spills on the Atlantic Coast of South America (Coast of Ceará State, Brazil).
Lima ADF, Lopes BD, Santana LMBM … +4 more , Martins MM, Nossol ABS, Goulart LR, Cavalcante RM
Mar Environ Res · 2026 Jun · PMID 41921341 · Publisher ↗
This study evaluated food safety and potential human health risks associated with the consumption of fish collected along the Ceará coast, Brazilian Equatorial Margin, after one of the largest oil spill events on the Atl...
This study evaluated food safety and potential human health risks associated with the consumption of fish collected along the Ceará coast, Brazilian Equatorial Margin, after one of the largest oil spill events on the Atlantic coast of South America. Twenty-one polycyclic aromatic hydrocarbons (PAHs), including carcinogenic and non-carcinogenic compounds, were quantified in muscle and liver tissues of 180 fish from 21 species, collected in September and October 2021, from three coastal areas (Canto Verde Beach, Jaguaribe River, and Icaraí Beach). Total PAHs concentrations ranged from 27.0 to 679.5 ng g (wet weight), with the highest levels consistently detected in fish from the Jaguaribe River. Low-molecular-weight PAHs predominated, particularly naphthalene, which reached 508.2 ng g in muscle tissue, while carcinogenic PAHs expressed as benzo[a]pyrene toxic equivalents (BaPE) reached a maximum of 3.80 μg g BaPE. Human health risk assessment was conducted using the level of concern (LOC) approach recommended by Brazilian Health Regulatory Agency (ANVISA - Agência Nacional de Vigilância Sanitária). All non-carcinogenic and carcinogenic PAHs concentrations were below their respective LOC thresholds, with maximum values approximately 13 times (non-carcinogenic PAHs) and 2 times (carcinogenic PAHs) lower than the regulatory limits. Although contamination levels were classified as low to moderate, the spatial concentration of gradients and dominance of petroleum-related PAHs indicate persistent environmental exposure. Overall, the results suggest a low immediate risk to human health through fish consumption; however, continued monitoring is essential to address long-term risks in oil-impacted tropical coastal systems.
Ecological functions of sea cucumber Apostichopus japonicus in oyster-kelp-sea cucumber IMTA mode: Organic matter extracting and disturbance-driven nutrient release.
Xie Y, Qin X, Fang J … +5 more , Zhang Y, Tong R, Xu J, Wang J, Zhang X
Mar Environ Res · 2026 Jun · PMID 41921340 · Publisher ↗
This study systematically evaluated the sediment remediation and nutrient cycling functions of sea cucumber (Apostichopus japonicus) across three size classes (small: 52.1 ± 4.22 g; medium: 88.5 ± 13.61 g; large: 119.24 ...
This study systematically evaluated the sediment remediation and nutrient cycling functions of sea cucumber (Apostichopus japonicus) across three size classes (small: 52.1 ± 4.22 g; medium: 88.5 ± 13.61 g; large: 119.24 ± 7.38 g) in a novel oyster (Crassostrea gigas) -kelp (Saccharina japonica) -sea cucumber integrated multi-trophic aquaculture (IMTA) system. Integrated methodologies included stable isotope analysis (δC, δN), carbon and nitrogen budget determinations, and monitoring of nutrient fluxes across sediment-water interface. Results sea cucumbers preferentially consumed aquaculture-derived biodeposits, which constituted the major component of surface sediments and possessed high nutritional value (>60% dietary contribution), primarily including oyster feces and suspended particulate matter (SPM) from oyster and kelp monoculture areas. Carbon and nitrogen budgets revealed a distinct size-dependent "low assimilation-high egestion" metabolic strategy, with small individuals exhibiting highest mass-specific oxygen consumption (0.013 mg O·g·h), peak ammonia excretion (0.725 μg NH-N·g·h), and superior net removal efficiencies for sedimentary organic carbon (53.1%) and nitrogen (34.6%). Bioturbation significantly enhanced nitrogen and phosphorus cycling, jointly modulated by body size and temperature: at temperatures <20.97 ± 0.38 °C, large individuals drove dissolved inorganic nitrogen (DIN) and PO-P fluxes 1.9 and 1.3 times higher, respectively, than small counterparts. Sustained exposure above this thermal threshold suppressed behavioral and metabolic activity across all size classes, progressively eliminating DIN and PO-P flux differentials between bioturbation treatments and controls. Thermal stress additionally altered benthic dissolved oxygen dynamics and nutrient speciation patterns. These findings will provide a theoretical basis for optimizing bioregulatory strategies in multi-trophic aquaculture systems.
Thermal risks and opportunities for a tropical invasive sea urchin in a fast-warming sea.
Preiss I, Raanan G, Zilberman S … +4 more , Fadida Y, Lapidot Z, Berman-Frank I, Rilov G
Mar Environ Res · 2026 Jun · PMID 41921339 · Publisher ↗
Ocean warming and bioinvasions act together in many ocean regions to rapidly tropicalize temperate and subtropical marine ecosystems. Tropicalization reshuffles natural communities where tropical species invade and estab...
Ocean warming and bioinvasions act together in many ocean regions to rapidly tropicalize temperate and subtropical marine ecosystems. Tropicalization reshuffles natural communities where tropical species invade and establish in new regions. But will some rapidly warming regions eventually become too warm for some tropical invaders? One place to test this is the southeastern Mediterranean, a global bioinvasion and warming hotspot. This study focuses on the non-indigenous sea urchin Diadema setosum, a recent fast-spreading Mediterranean invader, the Indo Pacific-Red Sea urchin. This research aims to address the present, and future fate of this invasion at the southeastern Mediterranean reef ecosystems given ocean warming, by defining the viable, optimal and lethal temperatures for the Mediterranean D. setosum populations. Specifically, the thermal performance of D. setosum was examined, focusing on metabolic, reproduction, and food assimilation rates as performance proxies. Results show an optimal seawater temperature range of 27-28 °C for metabolic rates, 20-24 °C for gonads growth and maturation as well as food assimilation, while mortality occurred at 36 °C. These results indicate that the urchin can survive even future warming above current peak summer temperatures of 32 °C but will enter the stressful thermal range with further seawater temperature elevation. The species might already physiologically underperform under current summer temperatures in the region, which might affect its population viability. However, warming might increase the probability of spreading to new colder regions. Thus, we expect that the invader will eventually occupy most Mediterranean regions, but fitness might be eroded in the warmest part, the SE Levantine basin.
Latitudinal patterns of food source assimilation and food-chain length in estuarine food webs.
Possamai B, Claudino MC, Pessanha ALM … +6 more , Giarrizzo T, Moraes LE, Clistenes AS, Goyenola G, Figueiredo GM, Garcia AM
Mar Environ Res · 2026 Jun · PMID 41921338 · Publisher ↗
Many hypotheses describe the complexity of food webs, particularly the 'productivity" and "ecosystem-size" hypotheses, both stating that these factors are positively related to food-chain length, increasing food web comp...
Many hypotheses describe the complexity of food webs, particularly the 'productivity" and "ecosystem-size" hypotheses, both stating that these factors are positively related to food-chain length, increasing food web complexity. Our goal was to identify the main environmental drivers of food-chain length (FCL) and the relative contribution of primary sources to communities in a latitudinal gradient of estuaries on the Southwestern Atlantic coast (0° - 34°S). We used stable isotope analyses (δC, δN) to calculate trophic positions (TP; tRophicPosition package in R), FCL, and primary sources assimilation (SIMMR package) by fish in eight estuarine communities of a latitudinal gradient (tropical to temperate-like estuaries). Relationships between environmental variables (chlorophyll-a, estuarine area, etc.), FCL, and primary sources assimilation were evaluated using GLM. FCL decreased with chlorophyll-a and increased with latitude. In tropical estuaries, mangrove was the major source supporting the community, changing to macroalgae and periphyton in subtropical latitudes and shifting again to saltmarsh and seagrass in temperate-like estuaries. The assimilation of phytoplankton increased with latitude, while mangrove decreased. Saltmarsh contribution to consumers was related to lower salinities. Summarizing, the latitudinal pattern was stronger than chlorophyll-a or ecosystem size in describing FCL. The main carbon sources supporting each food chain corroborated the expected distribution and abundance of primary producers from tropical to temperate zones. Climate change is rapidly increasing the intensity of natural phenomena and understanding past and current patterns in ecosystem attributes and functioning is imperative to predict biodiversity and ecosystem services losses and take measures to prevent disasters.
Hydrothermal influence reduces the nutritional quality of the Antarctic seaweed Monostroma hariotii (Chlorophyta).
Azcárate-García T, Figuerola B, Cara-Ortega CL … +4 more , Martín-Martín R, Beca-Carretero P, Stengel DB, Avila C
Mar Environ Res · 2026 Jun · PMID 41921337 · Publisher ↗
Seaweeds are foundational primary producers that support marine food webs. Their resilience in fluctuating environments is partially facilitated by their ability to synthesize diverse biochemical compounds with key physi...
Seaweeds are foundational primary producers that support marine food webs. Their resilience in fluctuating environments is partially facilitated by their ability to synthesize diverse biochemical compounds with key physiological roles, many of which also offer nutritional benefits to consumers. Because seaweed biochemical composition is shaped by environmental conditions, it is potentially sensitive to global change stressors such as ocean warming and acidification. Yet, species-specific biochemical responses of Antarctic seaweeds remain poorly understood. We studied fatty acid, carbon, nitrogen, and pigment levels in the green seaweed Monostroma hariotii Gain, 1911 (Chlorophyta) from two Antarctic stations representing ambient Antarctic conditions (Rongé and Amsler Islands), and compared them with specimens naturally exposed to elevated temperatures (⁓2.7-3.2 °C higher) and reduced pH (⁓1.2 units lower) at a fumarole vent site on Deception Island (South Shetland Islands). Specimens from Rongé and Amsler Islands exhibit high nutritional quality, with elevated polyunsaturated fatty acids (PUFA) n-3 (39.39 ± 1.11 and 37.37 ± 1.05% TFA, respectively), low C:N ratios (6.93 ± 0.05 and 7.20 ± 0.08, respectively), and abundant pigments. By contrast, specimens from the fumarole vent site had reduced PUFA n-3 (29.01 ± 2.48% TFA) and pigments, along with higher PUFA n-6 levels (⁓96-145% higher) and elevated C:N ratios (8.97 ± 0.30), suggesting a decrease in nutritional value under warmer and acidic conditions. Our findings suggest that ocean warming and acidification may alter the biochemical profile of M. hariotii, potentially leading to a decline in its nutritional value under future climate scenarios.
Mechanism of eutrophication in a semi-enclosed bay: Insight from dual water isotopes.
Silva DPTT, Lao Q, Chen C … +2 more , Cai S, Chen F
Mar Environ Res · 2026 Jun · PMID 41916041 · Publisher ↗
Under the dual pressures of global change and human activities, semi-enclosed bays, as critical zones of land-sea interaction, are experiencing increasingly severe eutrophication and significant ecological risks. Current...
Under the dual pressures of global change and human activities, semi-enclosed bays, as critical zones of land-sea interaction, are experiencing increasingly severe eutrophication and significant ecological risks. Current understanding of the causes of bay eutrophication predominantly focuses on environmental factors such as terrestrial nutrient inputs, often overlooking the regulatory role of hydrodynamic processes. In this study, we employed dual water isotopes (δD and δO), hydrographic and other physicochemical parameters from field observations across spring, summer, autumn, and winter of 2020 to explore the seasonal water dynamics and their interrelationship with eutrophication in Zhanjiang Bay, a semi-enclosed aquaculture bay in South China. The results showed that EI exhibited pronounced spatial and seasonal variability, and the upper bay consistently exhibited higher EI values than the lower bay. Summer season showed peak eutrophication among the four seasons, followed by the autumn, whereas eutrophication was lower in winter and spring. Dual isotope analysis combined with hydrographic data revealed a significant seasonal variation in the contribution of water masses, with high-salinity seawater intrusion dominating in summer and terrestrial freshwater dominating in autumn. Both of these processes can intensify salinity front within the bay, hindering the export of terrestrial nutrients and causing them to accumulate. By contrast, during the dry season (winter and spring), the reduction of terrestrial freshwater input and high-salinity seawater intrusion weakens the salinity gradient in the bay. This allows nutrients to diffuse toward the lower and outer bay, thereby decreasing the eutrophication load. The findings provide critical insights for coastal management and nutrient mitigation strategies in such tropical semi-enclosed bay systems.
Can filamentous algae intensify heat in intertidal rockweed beds?
Bekkby T, Rinde E, Christie H
Mar Environ Res · 2026 Jun · PMID 41916040 · Publisher ↗
Intertidal rockweed beds are often described as climate refuges for species, buffering harsh environmental conditions. Due to problems such as ocean warming, ocean acidification, eutrophication and trophic imbalance, man...
Intertidal rockweed beds are often described as climate refuges for species, buffering harsh environmental conditions. Due to problems such as ocean warming, ocean acidification, eutrophication and trophic imbalance, many areas are experiencing blooms of opportunistic filamentous algae, but little is known about how this shift affects the microclimatic conditions in canopy building seaweeds. Here we report some interesting findings from our ad hoc study on rockweeds (Fucus vesiculosus) being covered by filamentous algae during a hot spell. We found significantly higher temperature in filamentous algae aggregations than within rockweed patches. Also, the temperature in the filamentous algae was higher (up to 3.2 °C) than the surrounding water masses, a difference that was not found for the rockweed patches. Our results indicate that filamentous algae aggregations are trapping heat, which indicates that these algae can hamper the intertidal rockweed bed's role as a climate refuge for species when they occur in dense aggregations.
Nitrogen uptake preference of Avicennia marina and Aegiceras corniculatum in simulated saline water under varying salinities.
Su D, Hu J, Zhang C … +4 more , Yang Y, Zhu X, Guan J, Liu Y
Mar Environ Res · 2026 Jun · PMID 41916039 · Publisher ↗
High-salinity, nitrogen-rich aquaculture effluents exert increasing pollution pressure on coastal ecosystems. While constructed wetlands (CWs) vegetated with mangroves offer a promising nature-based solution, the specifi...
High-salinity, nitrogen-rich aquaculture effluents exert increasing pollution pressure on coastal ecosystems. While constructed wetlands (CWs) vegetated with mangroves offer a promising nature-based solution, the specific influence of salinity on their nitrogen (N) removal dynamics remains poorly understood. We assessed the N uptake preferences of Avicennia marina and Aegiceras corniculatum via a 24-h N labeling hydroponic experiment across four salinities (0-35 psμ), and separately evaluated their N removal performance in a 20-day CW microcosm treating saline aquaculture wastewater under identical salinity conditions. The results reveal that both species preferentially absorbed ammonium, with the roots serving as the primary site of uptake, and that their proportional reliance on ammonium declined as salinity increased. In the CW system, A. corniculatum demonstrated superior N removal capacity, achieving a dissolved inorganic N removal rate of 92.17 ± 0.94% by day 10. Its contribution via direct plant uptake (22.65-38.98%) was significantly higher than that of A. marina (7.51-9.40%). Although the share of direct sequestration was modest, both species acted as ecological catalysts, synergistically enhancing systemic denitrification via rhizosphere-mediated microbial processes. These findings provide a theoretical framework for optimizing species selection and N mitigation strategies in coastal ecological engineering.
On-board determination and ecological risk of Cu species in Yellow River Estuary.
Zhang Z, Han H, Lu Y … +3 more , Meng X, Wang N, Pan D
Mar Environ Res · 2026 Jun · PMID 41911637 · Publisher ↗
Copper (Cu) speciation was highly dynamic and could be biased by sample handling, storage and transport. In this study, an on-board electrochemical speciation analysis was used to quantify natural labile Cu (NL Cu) and t...
Copper (Cu) speciation was highly dynamic and could be biased by sample handling, storage and transport. In this study, an on-board electrochemical speciation analysis was used to quantify natural labile Cu (NL Cu) and total dissolved Cu (TD Cu) in surface and bottom waters of the Yellow River Estuary in winter immediately after collection. Along the main flow path toward the Bohai Sea (C1-C4), NL Cu was higher in surface water (0.87 μg/L) than in bottom water (0.73 μg/L) in the river-sea mixing zone because of the salinity as a key driver. The NL/TD Cu ratio decreased from nearshore to offshore. An integrated assessment combining contamination factor (C, TD Cu-based) with NL Cu-based ecological risk (SSD-derived PNEC and risk quotient, RQ) indicated that although C suggested relatively good water quality (C < 1), medium to high ecological risks could occur when NL Cu constituted a high proportion of TD Cu. This on-board approach coupled with the integrated framework might be applicable to Cu speciation research and ecological risk assessment in other estuaries.
Environmental variability shapes productivity and thermal responses of a free-living coralline alga.
Cerpelloni M, Nannini M, Gaspar TL … +4 more , Tuya F, Mourato CV, Silva J, Schubert N
Mar Environ Res · 2026 Jun · PMID 41911636 · Publisher ↗
Free-living coralline algae are key foundation species of worldwide distributed coralline algal beds, habitats recognized as biodiversity hotspots and significant sites of carbonate production. Among them, Phymatolithon...
Free-living coralline algae are key foundation species of worldwide distributed coralline algal beds, habitats recognized as biodiversity hotspots and significant sites of carbonate production. Among them, Phymatolithon lusitanicum forms extensive beds along the southern coast of Portugal, where frequent upwelling-downwelling alternations create a highly dynamic environment. These oceanographic shifts drive rapid changes in seawater temperature and light, with downwelling associated with higher values and upwelling with lower ones. This variability is likely to influence algal physiological performance and resilience to marine heatwaves (MHWs), which in this region often coincide with intense downwelling. Here, we examined the physiological responses of P. lusitanicum to simulated fluctuations in temperature and irradiance, with and without the superimposition of a MHW event, through a mesocosm experiment that realistically simulated natural fluctuations in temperature and light. Physiological responses (photosynthesis, respiration and calcification) were measured during upwelling, downwelling, and transitional periods. Phymatholithon lusitanicum showed considerable phenotypic plasticity, with physiological responses closely tracking environmental variability. Metabolic activity increased during downwelling, in terms of both primary and carbonate productivity, whereas upwelling periods led to negative net primary productivity and declines in calcification. Superimposing a MHW on a downwelling period caused no significant adverse effects, indicating high thermal tolerance. These results emphasize the dual role of environmental variability in regulating algal productivity and fostering resilience to extreme warming events, while highlighting the potential for strong negative impacts of cold spells, which represent the extreme end of upwelling regimes and occur as frequently as MHWs in the study region.
Influence of climate variability and shark interactions on artisanal deep-water fisheries in Spain's largest marine reserve.
Jiménez-Alvarado D, Espino-Ruano A, Guerra-Marrero A … +4 more , Cabana-Gandiaga J, Bañeras T, Castro-Hernández JJ, Couce-Montero L
Mar Environ Res · 2026 Jun · PMID 41911635 · Publisher ↗
Artisanal fisheries in the Canary Islands are an essential element of local livelihoods but face increasing challenges due to climate variability, access restrictions due incompatibility with other marine activities (i.e...
Artisanal fisheries in the Canary Islands are an essential element of local livelihoods but face increasing challenges due to climate variability, access restrictions due incompatibility with other marine activities (i.e. wind farm and aquaculture), and resource depletion. Moreover, in recent years, fishers operating in the deep-water artisanal fishery of northern Lanzarote reported significant declines in catches, attributing up to 30% of losses to shark depredation on their captures while hoisting. We combined fisher surveys (n = 26), onboard monitoring trips (between 2022 and 2023), and time-series analyses of landings (2006-2023) to evaluate the magnitude of this stealing sharks interactions and their ecological context. Survey data indicated frequent shark encounters, mostly involving shortfin mako (Isurus oxyrinchus), thresher sharks (Alopias spp.), and hammerhead sharks (Sphyrna spp.). However, direct observations during 317 monitored fishing sets recorded only two possible shark-related losses, representing just 0.7% of total fishing effort. By contrast, wavelet analyses of landing series revealed strong correlations between the North Atlantic Oscillation (NAO) and catch variability, with 8-18 month lags. Periods of negative NAO (2014-2017) coincided with exceptional recruitment of deep-water fish species and subsequent record catches between 2018 and 2020, followed by sharp declines after 2021. Our findings suggest that catch losses by stealing sharks, although occasionally perceived as severe by fishers, exerts only a minor direct effect on catches. Instead, climate-driven fluctuations in recruitment and stock availability largely explain observed trends. These results underscore the importance of incorporating climate indices into fisheries assessments and management, while continuing to monitor shark-fishery interactions given their potential socioeconomic implications.
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