Marine environmental research最新文献

{"title":"Relationships of the summer nutrient concentrations in the East China Sea with the Changjiang diluted water, upwellings and Kuroshio intrusion, from an interannual perspective","authors":"Qingling Zhang ,&nbsp;Xinyan Mao ,&nbsp;Yifei Luo ,&nbsp;Xinyu Guo ,&nbsp;Jie Shi","doi":"10.1016/j.marenvres.2026.107891","DOIUrl":"10.1016/j.marenvres.2026.107891","url":null,"abstract":"<div><div>In summer, the East China Sea (ECS) faces ecological challenges like harmful algal blooms, hypoxia, and jellyfish blooms, linked to nutrient distributions influenced by Changjiang Diluted Water (CDW), Kuroshio intrusion, and Zhejiang Coastal Upwelling (ZCU). The inconsistent interannual variations of these processes complicate nutrient dynamics. This study used the Empirical Orthogonal Function (EOF) analysis to reveal the interannual variations (1993–2022) of summer dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) concentrations in the ECS. We demonstrated that interannual variability in southerly wind strength was a key regulator controlling the relative influence of CDW and ZCU on surface nutrients. Weaker southerly wind combined with stronger Changjiang discharge (e.g., 1999, 2002, 2020) enhanced the nearshore influence of CDW and reduced the ZCU intensity. This suppressed DIP supply and biological consumption of DIN, leading to accumulated surface DIN but depleted surface DIP in the Zhejiang Coastal (ZC) region. Conversely, stronger southerly wind combined with stronger Changjiang discharge drove the CDW moving offshore that increased offshore DIN concentrations. Simultaneously, the stronger southerly wind also intensified ZCU that enhanced coastal DIP supply and biological DIN uptake, resulting in reduced coastal surface DIN. Critically, we identify the distinct drivers for bottom DIP. Weaker ZCU led to increasing (decreasing) of bottom DIP concentrations in an area deeper (shallower) than 20 m, while stronger Kuroshio intrusion substantially boosted bottom DIP, influencing productivity in both ZC region and the East Zhejiang coastal (EZC) region. The intricate interplay of these physically driven nutrient fluxes, characterized by differing N/P ratios, underpinned the ECS's complex and variable summer nutrient structures with profound implications for understanding its ecological responses.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107891"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146113150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial richness patterns of large pelagic fishes in the Eastern Pacific Ocean","authors":"Aura Buenfil-Ávila ,&nbsp;Sofia Ortega-García ,&nbsp;Héctor Villalobos ,&nbsp;Javier Nori ,&nbsp;Ulianov Jakes-Cota ,&nbsp;Rodrigo Moncayo-Estrada ,&nbsp;Gabriel Reygondeau","doi":"10.1016/j.marenvres.2026.107860","DOIUrl":"10.1016/j.marenvres.2026.107860","url":null,"abstract":"<div><div>In the Eastern Pacific Ocean, the purse seine tuna fishery targets skipjack, yellowfin tuna, and bigeye tuna. However, bycatch of billfish is also common. Growing concerns about the rising bycatch levels and the capture of juveniles’ tunas underscore the need for spatial explicit management strategies. This study aims to model the geographic distributions of four tuna species (skipjack, yellowfin, bigeye, and black skipjack) and five billfish species (swordfish, sailfish, striped marlin, blue marlin, and black marlin) to understand how interannual variability shapes richness patterns of these species to inform spatial management efforts. Species distribution models were developed using MaxEnt based on environmental scenarios representing cold, neutral, and warm conditions from 2000 to 2020. A database of occurrences was compiled from Inter-American Tropical Tuna Commission's, while environmental variables were obtained from Copernicus Marine Service. Predicted distribution maps for each species were combined to generate species richness maps under different environmental scenarios. Areas of high species richness were identified near the Baja California peninsula, the southern Gulf of California, off the coast of Central America, and between the Ecuadorian coast and the Galapagos Islands, regions that overlap with known spawning and feeding grounds. Species richness patterns showed an interannual variability, expanding during warm periods and contracting during neutral and cold conditions, highlighting the need to adapt spatial management to environmental variability of oceans. These findings provide a basis for future spatial planning and conservation initiatives, highlighting the need for dynamic, flexible conservation strategies that can adapt to a changing ocean.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107860"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monsoon mysteries: Impact of rainfall-induced hydrographic changes on coastal zooplankton communities","authors":"Tanmoy Nandy ,&nbsp;Sabyasachi Sautya ,&nbsp;Santosh Gaikwad ,&nbsp;Rakesh P.S. ,&nbsp;Balaram Sahu","doi":"10.1016/j.marenvres.2026.107896","DOIUrl":"10.1016/j.marenvres.2026.107896","url":null,"abstract":"<div><div>In tropical coastal ecosystems, monsoonal rainfall is a critical driver of seasonal variability, inducing shifts in hydrological parameters such as temperature, salinity, and nutrient concentrations, which subsequently regulate zooplankton community structure. This study investigated the influence of the southwest monsoon on coastal water quality and zooplankton composition along the Mumbai coast, India. Sampling was conducted in the pre-monsoon (May 2022) and post-monsoon (September 2022) periods, corresponding to early (EMP) and later (LMP) monsoonal phases, during which the region receives 1500–2000 mm of precipitation. Analyses revealed distinct hydrological changes and a significant reorganisation of the zooplankton assemblage between phases. Total zooplankton abundance was lower in the EMP compared to the LMP. Among the 25 taxonomic groups identified, Copepoda dominated the community, represented by 27 species (23 Calanoida, 2 Harpacticoida, and 2 Cyclopoida), with families Acartidae and Paracalanidae comprising 70 % of the copepod population. Statistical and biological trait-based analyses demonstrated significant temporal shifts in copepod community composition and functional structure. Temperature, salinity, and nutrient levels were identified as the primary environmental factors shaping the distribution of copepod functional groups. Eleven copepod taxa served as indicator species for specific monsoonal phases. Trophic structure analysis showed a prevalence of omnivorous copepods during the EMP, likely due to reduced phytoplankton availability under lower nutrient concentrations and fluctuating salinity, favouring opportunistic feeding. In contrast, the LMP, characterised by elevated nutrient inputs and stabilised salinity, supported a more complex food web with a balanced representation of herbivorous, omnivorous, carnivorous, and detritivorous functional groups. Herbivores were numerically dominant in both periods. The increased co-dominance of meroplankton (pelagic larvae of benthic invertebrates) during the LMP highlighted their ecological role in coupling benthic and pelagic subsystems. These findings elucidate the mechanistic links between monsoonal hydrography and zooplankton functional ecology, providing a scientific basis for informed conservation and management of monsoon-influenced coastal ecosystems.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107896"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146137557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationship between biofouling abundance on wood and the recruitment and growth of the wood-boring bivalve Bankia martensi (Stempell, 1899) - Seasonal and bathymetric variations","authors":"Boris A. López","doi":"10.1016/j.marenvres.2026.107866","DOIUrl":"10.1016/j.marenvres.2026.107866","url":null,"abstract":"<div><div>The marine wood-boring bivalve <em>Bankia martensi</em> (Stempell, 1899) is the primary agent responsible for wood degradation along the Chilean coast. However, there is limited understanding of its interactions with other marine wood-biofouling species. Previous studies have shown an inverse relationship between biofouling cover on wood and the recruitment and growth of <em>B. martensi</em>. These trends may vary over time and at different depths. Consequently, during the austral autumn and spring of 2024, pine wood panels (25 x 15 × 5 cm) were submerged at three different depths (1, 3, and 5 m below the water surface) in Metri Bay (41°36′S; 72°42′W). After five months, <em>B. martensi</em> recruitment and size were assessed, along with biofouler cover and biomass on the panels. The recruitment and size of <em>B. martensi</em> were higher in spring (1.7 ± 0.3 perforations∗cm⁻²) than in autumn (0.5 ± 0.2 perforations∗cm⁻²) and diminished with increasing depth (mainly at 5 m). Inverse associations were observed between the recruitment and size of <em>B. martensi</em> specimens and the cover and biomass of the main biofouler species. These results suggest that the presence of biofouling species influences larval settlement and growth of <em>B. martensi</em>. Furthermore, these potential interspecific competition relationships change depending on season and depth, thereby affecting the rate at which xylophagous species degrade wood. Manipulative experiments with biofouler species, as well as measurements of the reproductive traits of <em>B. martensi</em>, could help us understand the biological interactions between marine wood borers and biofouler species.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107866"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Harnessing the power of Squidle+ to develop flexible machine learning models","authors":"Leonard Günzel ,&nbsp;Jacquomo Monk ,&nbsp;Chris Jackett ,&nbsp;Ariell Friedman ,&nbsp;Ashlee Bastiaansen ,&nbsp;Ardalan Najafi ,&nbsp;Alberto García Ortiz ,&nbsp;Neville Barrett","doi":"10.1016/j.marenvres.2026.107888","DOIUrl":"10.1016/j.marenvres.2026.107888","url":null,"abstract":"<div><div>While our ability to capture seafloor imagery has expanded dramatically, extracting information remains a major bottleneck, as annotation is still largely manual, time-consuming, and costly. Machine Learning (ML) classifiers offer a promising solution, but they often lack generalisation as they are typically trained on small, homogeneous datasets from selected campaigns. Here, we address this challenge by leveraging the Squidle+ platform to assemble a heterogeneous dataset of 1.7 million annotations across 150,000 images from 325 expeditions in Australian waters. To effectively train models on this scale, we introduce a novel dataset distribution strategy, the neighbour-distribution, and implement adaptive cropping to account for varying image resolutions. To assess performance at a national scale, we excluded entire campaigns from training and used them as independent test sets, allowing evaluation on complete transects, in addition to composed datasets. Using this flexible training pipeline, we combined diverse annotation schemes into three high-level Essential Ocean Variables (EOVs): Seagrass, Canopy-Forming Macroalgae, and Hard Coral cover and one species-specific label, <em>Ecklonia radiata</em>. This represents the first use of such a large and diverse dataset for training an ML classifier of <em>Ecklonia radiata</em>. The resulting models achieved test accuracies of 85%–93% for the EOVs and 96.5% for <em>Ecklonia radiata</em> on campaign test sets spanning Australia’s coastline, demonstrating robust performance at a national scale. To enhance accessibility, both the code and trained models are made publicly available and directly integrated into Squidle+, lowering the barrier for their use in ecological monitoring programs.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107888"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146170834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A remote sensing framework unveiling the life-cycle dynamics and environmental drivers of Ulva prolifera green tides in the South Yellow Sea","authors":"Yijie Tang ,&nbsp;Mengquan Wu ,&nbsp;Jie Zhao ,&nbsp;Shaopeng Luan ,&nbsp;Pengsen Yang ,&nbsp;Longxing Liu ,&nbsp;Bowen Liu ,&nbsp;Jinyi Lv ,&nbsp;Gang Chen ,&nbsp;Hongyu Kan ,&nbsp;Yuying Ran ,&nbsp;Huining Lai","doi":"10.1016/j.marenvres.2026.107920","DOIUrl":"10.1016/j.marenvres.2026.107920","url":null,"abstract":"<div><div>Since 2007, recurrent large-scale <em>Ulva prolifera</em> green tides in the South Yellow Sea have posed severe ecological and socioeconomic threats. However, previous studies often homogenized bloom processes and faced challenges in accurate detection under complex conditions. To better characterize its spatiotemporal dynamics and environmental drivers, this study integrated multi-source remote sensing data from 2018 to 2024 and proposed a five-stage life-cycle framework. We developed the VB-FAH-Otsu model by combining the Virtual Baseline Floating Algae Height Index (VB-FAH) with the Otsu algorithm, which demonstrated robust performance (F1 &gt; 0.89, MCC ≥0.893) under complex marine conditions. Key findings include: (1) The green tide life cycle—comprising emergence, development, outbreak, decline, and disappearance—exhibits strong temperature dependence, with rapid biomass accumulation at sea surface temperatures (SST) of 15–24 °C and a sharp decline (∼85% coverage loss within 28 days) above the critical 24 °C threshold. (2) Spatiotemporal patterns are governed by the interplay of oceanic dynamics and environmental gradients. The green tide centroid migrated northeastward at approximately 0.8 km day⁻¹, consistent with wind-driven currents. The southern coast of the Shandong Peninsula, under weak wind disturbance and stable thermohaline conditions (monthly SST variation &lt;2 °C), served as a persistent refuge area, with a significantly higher outbreak frequency (14.2 ± 3.1 events) compared to the more dynamic offshore waters of Jiangsu. This study establishes a comprehensive remote sensing framework for monitoring green tide dynamics and provides a scientific basis for early warning and cross-regional management strategies.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107920"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146171032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The stress of multiple factors leads to the decline of oyster reefs: a case study of Tianjin Dashentang oyster reefs","authors":"Qiang Wang ,&nbsp;Honghui Zhu ,&nbsp;Jinghui Fang ,&nbsp;Ruixue Tong ,&nbsp;Yumeng Xie ,&nbsp;Biao Guo ,&nbsp;Lei Jia","doi":"10.1016/j.marenvres.2026.107904","DOIUrl":"10.1016/j.marenvres.2026.107904","url":null,"abstract":"<div><div>The Dashentang waters of Tianjin contain China's largest remaining natural oyster reef, an ecosystem facing multiple stressors, including overfishing, industrial pollution, and climate change. These pressures have led to measurable contraction in reef area and declining oyster population densities. However, limited knowledge exists regarding population dynamics of <em>Crassostrea gigas</em> in artificial oyster reef (Ax: A1-A5 five stations) and natural oyster reef (Nx: N1-N5 five stations) habitats and their tolerance to intra-annual water quality fluctuations. This study investigated the biological parameters of the <em>C. gigas</em> population dynamics and associated physicochemical water quality factors in both Ax and Nx habitats in the middle of the four target months (March, June, September, and December) of 2024. Condition index of <em>C. gigas</em> populations declined significantly in summer, reaching minima in autumn. Empty shells (EOS) markedly in autumn, while living oysters (LO) showed divergent trends during winter, increasing in Ax but decreasing in Nx. Precipitation of 227.00 mm reduced salinity to a range of 23.30–24.38 during September. Significant negative correlations emerged between EOS and salinity (<em>P &lt;</em> 0.05), while a highly significant positive correlation was observed between LO and salinity in the Nx habitat (<em>P &lt;</em> 0.01). During summer, the bottom layer total particulate matter (TPM) concentrations at station A1 was 168.53 mg L⁻¹, with EOS at 125.00 ind·m⁻² and complete absence of LO. In autumn, the bottom-layer TPM at station N5 measured 139.90 mg L⁻¹, while EOS was 375.00 ind·m⁻² and LO was 212.50 ind·m⁻². During the same season, the dissolved oxygen declined to 2.32 mg L⁻¹ at station A2, with EOS at 518.75 ind·m⁻² and LO was only 12.5 ind·m⁻². Supra-threshold hypoxia, salinity fluctuations, and elevated TPM loading collectively triggered mass mortality events in both reef habitats during autumn. In winter, recovery in Nx was constrained by TPM-mediated sedimentation and fishing pressure, while unique structure facilitated population reestablishment in Ax. Thus, implementing ecosystem-based fisheries management coupled with three-dimensional oyster reef optimization represents an effective restoration strategy. This study provides a practical reference and theoretical basis for the formulation of oyster reef restoration strategies.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107904"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146143040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jellyfish-specific trophic footprint: Obelia sp. bloom reshapes plankton biomass flow in a coastal lagoon","authors":"M.C. López-Abbate ,&nbsp;A.S. Gilabert ,&nbsp;S.H. Lee ,&nbsp;J.C. Molinero ,&nbsp;D. Bonnet","doi":"10.1016/j.marenvres.2026.107906","DOIUrl":"10.1016/j.marenvres.2026.107906","url":null,"abstract":"<div><div>Gelatinous zooplankton are often represented as a single functional group in ecosystem-wide frameworks and biogeochemical models, despite growing evidence that species-specific feeding traits and seasonal dynamics may lead to contrasting planktonic responses. Here, we compared plankton community structure and biomass flow across three different years, including one year characterized by a bloom of <em>Obelia</em> sp., a microphagous, filter-feeding hydromedusa, and two non-bloom years. During the bloom year, patterns in plankton biomass were consistent with an enhanced role of microbial pathways, with bacterial abundance positively associated with <em>Obelia</em> sp., potentially reflecting increased availability of jellyfish-derived dissolved organic matter. This was accompanied by transient increases in nanoflagellates and ciliates, compatible with a short-lived microbial cascade in which these groups may have contributed to prey availability for <em>Obelia</em> sp. At the same time, weak coupling between bacteria and their grazers during the bloom suggests that a substantial fraction of jelly-derived organic matter may have been processed through bacterial respiration rather than transferred efficiently to higher trophic levels. Following the bloom, the community exhibited fewer interactions among the groups assessed in this study, along with a poor recovery of mesozooplankton biomass in the subsequent year. Although the <em>Obelia</em> sp. bloom declined rapidly, lasting less than a month, its effects on microbial community structure through its selective feeding on motile protists were more persistent. Taken together, these observations are consistent with the hypothesis that intense <em>Obelia</em> sp. blooms can coincide with transient reorganization of planktonic trophic pathways, although broader inference is limited by the observational nature of the study and the occurrence of a single bloom event.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107906"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146157811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Centennial environmental evolution and human activity impacts recorded by sedimentary diatoms in the Pearl River estuary","authors":"Yaqi Zhao ,&nbsp;Yuanliang Zhao ,&nbsp;Xiangwei Zhao ,&nbsp;Sujata Nilajkar ,&nbsp;Liuling Cheng ,&nbsp;Wenxin Zhou ,&nbsp;You Le ,&nbsp;Yang Lu ,&nbsp;Jun Sun","doi":"10.1016/j.marenvres.2026.107882","DOIUrl":"10.1016/j.marenvres.2026.107882","url":null,"abstract":"<div><div>Sedimentary diatom assemblages are sensitive bio-archives that can be used to reconstruct past environmental conditions in aquatic ecosystems. However, quantitative sedimentary records capable of precisely resolving anthropogenic impacts from natural variability in highly dynamic estuaries remain poorly understood. Here, we conducted a high-resolution diatom analysis of two ²¹⁰Pb-dated sediment cores (Z4-2 and Z5-2) from the Pearl River Estuary (PRE), covering the period 1938–2023 and 1893–2023, respectively. Our results identified a total of 66 diatom species and revealed a profound ecological shift. Prior to 2000, the diatom assemblage was dominated by planktonic taxa such as <em>Cyclotella striata</em> and <em>C. stylorum</em>, whose fluctuations reflected natural climate variability. In contrast, the period after 2000 was characterized by the dominance of the benthic species <em>Paralia sulcata</em>, which exceeded 50% abundance, accompanied by a sharp decline in freshwater species. This trajectory quantitatively demonstrates that anthropogenic forcing, including industrial pollution and coastal development, has surpassed natural climate variability as the primary driver of environmental change in the estuary in recent decades. These findings provide a critical baseline for distinguishing natural cycles from human-induced shifts, thereby offering a scientific basis for informed management decisions in the PRE and other anthropogenically influenced estuary ecosystems.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107882"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146125562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying the effect of biomass magnitude on apparent methylmercury toxicity in marine phytoplankton","authors":"Owhonda Chikeru Ihunwo,&nbsp;Edward A. Laws","doi":"10.1016/j.marenvres.2026.107861","DOIUrl":"10.1016/j.marenvres.2026.107861","url":null,"abstract":"<div><div>Methylmercury (MeHg) is a potent neurotoxin whose ecological impacts begin at the base of marine food webs, yet laboratory toxicity assays often rely on phytoplankton biomass levels far exceeding those found in natural waters. This discrepancy obscures true per-cell sensitivity and complicates cross-species comparisons. Here, we quantify the influence of initial biomass on apparent MeHg toxicity across five ecologically and taxonomically diverse marine phytoplankton—<em>Thalassiosira pseudonana</em>, <em>Cricosphaera carterae</em>, <em>Emiliania huxleyi</em>, <em>Synechococcus elongatus</em>, and <em>Phaeodactylum tricornutum</em>. Dose–response experiments were conducted across a gradient of initial optical densities (OD₇₅₀), and EC₅₀ values were estimated using nonlinear regression. Log₁₀-transformed EC₅₀ values exhibited strong linear relationships with OD₇₅₀ for most species, demonstrating a consistent biomass buffering effect in which higher cell densities reduce apparent MeHg toxicity. Extrapolation of regression models to OD = 0 yielded intrinsic, biomass-normalized EC₅₀ values that converged more tightly across taxa than raw EC₅₀ measurements, revealing a shared physiological sensitivity range once biomass artifacts were removed. <em>Cricosphaera carterae</em> was the most sensitive species (EC₅₀ = 0.0015 μg/L), while <em>Synechococcus elongatus</em> was the most tolerant (EC₅₀ = 43.86 μg/L). These biomass-adjusted EC₅₀ values were used to construct a species sensitivity distribution (SSD), from which an HC₅ of 2.25 x 10⁻<strong>³</strong> μg/L was estimated. Following the EPA acute-criteria relationship (FAV = 2 × HC₅), a Final Acute Value (FAV) of 4.50 x 10⁻<strong>³</strong> μg/L was derived. These findings demonstrate that biomass strongly modulates apparent MeHg toxicity and that biomass-adjusted EC₅₀ values serve as useful upper-bound estimates of per-cell sensitivity. This framework provides a reproducible method for normalizing toxicity data across taxa and improves the interpretation of contaminant sensitivity under low-biomass conditions without directly predicting ecological risk in situ.</div></div>","PeriodicalId":18204,"journal":{"name":"Marine environmental research","volume":"216 ","pages":"Article 107861"},"PeriodicalIF":3.2,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}