Search Results (289)

This study aimed to determine how spatial and seasonal variations influence the trophic structure of fish assemblages in the eastern Yellow Sea during 2023. Carbon and nitrogen stable isotope analyses revealed significant but spatially variable differences in δ¹³C and δ¹⁵N values among seasons and sites, without consistent overarching trends. These results suggest that phytoplankton-derived organic matter predominantly supports the regional food web, with isotopic niche shifts reflecting local differences in prey availability and hydrographic conditions. The findings contribute to the development of adaptive, ecosystem-based fishery management strategies amid increasing anthropogenic and climatic pressures. Full article

Biomass of the plumose anemone Metridium senile has surged in the benthic ecosystem of the North Yellow Sea in recent years. Understanding its diet and the proportional contributions of food sources is essential for assessing the ecological consequences of this expansion. The species is often characterized as a passive suspension feeder, yet laboratory feeding trials have documented shrimp consumption. Because prior dietary information from the region is scarce, conventional stable isotope approaches are poorly constrained. We developed an integrative framework coupling trophic position estimation, isotopic niche metrics, spatial point pattern analysis, and a Bayesian mixing model to improve diet attribution under limited prior information and to test whether M. senile preys on small-bodied and juvenile teleosts and invertebrates under natural conditions. Our analyses showed that: (i) M. senile occupied a high trophic position (TP = 3.09 ± 0.25), exceeding those estimated for putative predators in our dataset, implying weak top-down control; (ii) in isotopic niche analyses, M. senile showed high posterior probabilities of occurring within the niches of cephalopods and medium-sized fishes (78.30% and 63.04%, respectively), consistent with shared prey and inconsistent with a strictly suspension-feeding strategy; (iii) mixing space diagnostics informed by spatial point pattern analysis indicated that including small-sized fishes and shrimps as sources was necessary to reconcile the elevated TP; and (iv) the Bayesian mixing model estimated that small-bodied and juvenile teleosts and invertebrates supplied most long-term nutrition (posterior mean ≈ 0.65), with the remainder from suspension-derived sources, consistent with an opportunistic generalist rather than a strict suspension feeder. Sustained predation on small-bodied and juvenile teleosts and invertebrates could suppress early fish recruitment, impose top-down control on forage species, and alter the local food web structure. Management should monitor M. senile (size structure, population density, and co-occurrence with juveniles and forage biota) and consider targeted removals and seafloor litter cleanups in priority habitats. The framework is applicable to diet studies with limited prior information; adding δ³⁴S, compound-specific amino-acid isotopes (CSIA-AA), and DNA-based dietary evidence should further sharpen source discrimination. Full article

Freshwater ecosystems face increasing contamination by heavy metals, yet their transfer patterns remain poorly understood. This study aimed to assess the extent of pollution by ten potential toxic elements (As, Ni, Zn, Pb, Cd, Cr, Fe, Cu, Mn and Se) in water, sediment, Spirogyra sp., and two endemic fish species (Tropidophoxinellus callensis and Luciobarbus callensis) in the El Mellah River. The element concentrations were measured in four matrices using inductively coupled plasma optical emission spectrometry. Bioaccumulation Factor and Trophic Transfer Factor were used to depict bioaccumulation patterns across the ecological strata and two levels of the food web. The results showed that all sediment samples demonstrated very high ecological risk, consistently exceeding critical thresholds (PLI > 1, RI > 600). Contamination factor and geoaccumulation index revealed moderate to extreme contamination by As and Cd throughout all samples. Both fish species exhibited a bio-accumulation affinity for Cr, Cd, Mn, and Zn from water, while concurrently accumulating As from Spirogyra sp. Muscle tissue concentrations of As, Pb, Cr, and Cd in both species exceeded international guideline values. Health risk assessment indicated that children face elevated exposure risks, with Cd intake exceeding safe limits and total hazard quotient surpassing safety thresholds by 2.6-fold, while carcinogenic risks from Cd and Cr exceeded acceptable levels for both adults and children. These findings provide baseline contamination data for this tributary system and highlight elevated risks to both human health (through fish consumption) and ecosystem integrity, indicating the need for targeted monitoring and risk management measures. Full article

Keystone species play a critical role in sustaining ecosystem structure and function. Thus, accurately identifying keystone species is essential for effective biodiversity conservation. This study investigates the benthic ecosystem of Yanpu Bay’s mangroves, utilizing stable isotope analysis in combination with Bayesian mixture models and ecological network analysis to characterize trophic relationships and topological network structures, with the aim of identifying keystone species within the community. The benthic food web in this study comprised 96 connections and 27 nodes. Among them, Scartelaos histophorus preyed on eight benthos species, constituting 18.51% of the total prey sources in food web. Sedimentary organic matter (SOM) was identified as a critical food source, sustaining 17 consumer species, 62.96% of the total species recorded in the community. Quantitative analysis using criticality indices and key player problem indices identified Cerithidea cingulate, Littorinopsis scabra, Periophthalmus magnuspinnatus, S. histophorus, Bostrychus sinensis, and Metaplax longipes as keystone species. The identification of these keystone species provides valuable insights for developing targeted biodiversity conservation strategies and offers a robust scientific foundation for the restoration and sustainable management of the mangrove benthic food web. Full article

Given the high sensitivity of small estuaries to environmental changes, the present study aimed to investigate how climate-induced stressors—particularly rainfall and salinity—affect zooplankton community structure in the Amazonian Taperaçu estuary (northern Brazil), where limited spatial scale amplifies ecological responses. This study evaluated the effects of the extremely dry 2015–2016 El Niño period on hydrological patterns and zooplankton dynamics in this shallow tropical estuary. Eight sampling campaigns were conducted, with water and zooplankton samples analyzed using standard methods. Salinity, dissolved inorganic nutrients, and chlorophyll-a concentrations were affected by the marked decrease in rainfall caused by the El Niño event. These changes significantly impacted zooplankton community dynamics, especially the densities of marine-estuarine species Acartia lilljeborgii, Euterpina acutifrons, and Oikopleura dioica, which peaked during months of highest salinity. High recruitment of copepod larval stages was also observed, with peak densities coinciding with dominant adult forms. In contrast, coastal and estuarine species such as Acartia tonsa, Pseudodiaptomus marshi, Oithona oswaldocruzi, and Oithona hebes were negatively affected by reduced rainfall. Species richness, diversity, and evenness during the El Niño period were relatively high compared to previously reported values under normal conditions in the same ecosystem. Environmental and temporal variables accounted for over half the variance in predominant taxa density, indicating that El Niño–driven changes influenced zooplankton structure over time. This suggests that El Niño may have strong impacts at the secondary trophic level, likely to cascade throughout the estuarine food web, altering its dynamics and the flow of carbon and energy through the system. Full article

The rapid growth of the human population and industrialization has intensified anthropogenic activities, leading to the release of various toxic chemicals into the environment, triggering significant risks to human health and ecosystem stability. One sustainable solution to remove toxic chemicals from various environmental matrices, such as water, air, and soil, is bioremediation, an approach utilizing biological agents. Microalgae, as the primary producers of the aquatic environment, offer a versatile bioremediation platform, where their metabolic processes break down and convert pollutants into less harmful substances, thereby mitigating the negative ecological impact. Besides the CO₂ sequestration potential, microalgae are a source of renewable energy and numerous high-value biomolecules. Additionally, microalgae can mitigate various toxic chemicals through biosorption, bioaccumulation, and biodegradation. These remediation strategies propose a sustainable and eco-friendly approach to address environmental pollution. This review evaluates the microalgal mitigation of major environmental contaminants—heavy metals, pharmaceuticals and personal care products (PPCPs), persistent organic pollutants (POPs), flue gases, microplastics, and nanoplastics—linking specific microalgae removal mechanisms to pollutant-induced cellular responses. Each section explicitly addresses the effects of these pollutants on microalgae, microalgal bioremediation potential, bioaccumulation process, the risks of trophic transfer, and biomagnification in the food web. Herein, we highlight the current status of the microalgae-based bioremediation prospects, pollutant-induced microalgal toxicity, bioaccumulation, and consequential biomagnification. The novelty of this review lies in integrating biomagnification risks with the bioremediation potential of microalgae, providing a comprehensive perspective not yet addressed in the existing literature. Finally, we identify major research gaps and outline prospective strategies to optimize microalgal bioremediation while minimizing the unintended trophic transfer risks. Full article

Microplastic pollution is pervasive in marine ecosystems and poses a growing threat to marine organisms and human health. This study simultaneously investigates microplastic ingestion and phthalate exposure in Parapenaeus longirostris, a commercially valuable and ecologically relevant Mediterranean crustacean occupying an intermediate trophic position. Specimens were collected from three coastal areas in the central Tyrrhenian Sea (Western Mediterranean): near the Tiber River mouth, one of the most polluted rivers in Italy, and two additional sites to the north and south. The frequency of individuals with ingested microplastics varied among locations: 78% near the Tiber River, 64% at site S, and 38% at site N, reflecting anthropogenic pressure gradients. Analyses confirmed the lower occurrence at site N, indicating higher ingestion near land-based pollution sources. Ingested microplastic polymer types varied among sites, reflecting location-specific contamination. Phthalates were present in shrimp muscle at all sites (5–1122 ng/g w.w.) with the highest average concentration (68.26 ± 55.74 ng/g) at the site with the highest microplastic ingestion. Although no statistical correlation was found, the similar spatial distribution of microplastics and phthalates suggests a potential link influenced by local pollution and individual variability. These findings provide novel evidence of microplastic and phthalate contamination in P. longirostris, highlighting its role as a trophic connector mediating contaminant transfer through the food web. While current levels suggest no potential risk to human health, continued monitoring and further studies on exposure along trophic pathways are recommended. Full article

High doses of the antibiotic azithromycin in freshwater environments can impact planktonic organisms at both the individual and community levels, influencing interactions at the base of the food web. This study investigated the effects of azithromycin on the natural rotifer community feeding on phytoplankton from a eutrophic water body and its potential impacts on rotifer fitness (impaired mastax movement: slow, irregular or reduced frequency), grazing and mortality following acute exposure. The natural plankton community was exposed to three azithromycin concentrations based on the EC₅₀ value (EC₅₀, 1/2 EC₅₀ and 1/3 EC₅₀) and assessed at different exposure times (24, 48 and 72 h) in the microcosm experiments. The results showed that all azithromycin concentrations reduced the fitness of the rotifers, as indicated by impaired mastax movement and/or slow, irregular or reduced movement frequency. Impairment of mastax movement altered rotifer grazing and the abundance of phytoplankton. The rotifers in the control group suppressed abundant phytoplankton growth, suggesting that azithromycin impairs interspecific interactions between plankton species. Rotifer mortality occurred at 48 h after azithromycin exposure in all treated samples. These findings show that the effects of azithromycin can be observed at different trophic levels, affecting both phytoplankton and zooplankton through altered biotic interactions and suppressed grazing. Full article

Elucidating the relationship between changes in insect assemblage structure and diversity and the number of years of ecological restoration will help us evaluate the effectiveness of ecological restoration. Our objective is to investigate the response of the structure and diversity of insect communities in the ecological restoration area of Yimin Surface Mine in Inner Mongolia to different restoration years (1 year, 4 years, 7 years) by monitoring in 2018, 2021, and 2024. A total of 1282 insect specimens were collected using sweep-netting methods, representing 70 species from 46 families across 8 orders. The results demonstrated that as restoration progressed, insect taxa significantly increased from 25 to 55 species (p < 0.01), with key functional groups (Coleoptera and Lepidoptera) showing marked richness enhancement. α-diversity indices (Shannon–Wiener and Margalef) significantly increased, while the Simpson dominance index decreased, indicating a more homogeneous species distribution. β-diversity analysis revealed reduced compositional dissimilarity among plots during later restoration stages, reflecting enhanced assemblage stability. The trophic structure shifted from phytophagous dominance to stabilized proportions across all feeding guilds, signaling food web maturation and ecosystem development. Overall, local ecological restoration projects had a significantly positive effect on insect survival and biodiversity development. Our research addresses a gap in faunal assemblage studies of coal mine rehabilitation zones. Full article

Trace metal (TM) concentrations and carcinogenic risk were determined in ninety-two edible samples of the triggerfish Balistes spp. from the RAMSAR site 1826 San Ignacio-Navachiste-Macapule Lagoon Complex (NAV). The acid digestion method and an atomic absorption spectrophotometer were used to determine TM concentrations. Calibration curves were carried out using TORT-3 reference materials. The blank and certified reference materials were treated using the same procedure as a sample. TM sequence was Zn > Fe > Mn > Cu = Pb > Ni > Cd, and a correlation (p = 0.0169) between size and concentrations was found. No correlation (p = 0.079) was found between weight and concentrations, or sampling sites and the concentrations. The highest concentrations were found during the summer, followed by the spring and winter of 2017, while the lowest was found in the winter of 2018. The Zn was significantly higher in summer-17. The Target Hazard Quotient (THQ) was <1 for Pb, Ni, Cd, Fe, Zn, and Cu, and 1.39 for Mn. Cd and Pb resulted in carcinogenic potential (CsFo < 1) with a very low probability. The TM concentrations and bioaccumulation in triggerfish showed no consumption risk, due to its omnivorous diet, and trophic transfer rates were described for aquatic food webs. Full article

Phytoplankton–mesozooplankton interactions play a central role in shaping Black Sea food web dynamics, yet their trophic coupling has been insufficiently investigated in policy-relevant frameworks. This systematic review of 86 peer-reviewed studies (1987–2025) synthesizes research trends, limitations, and knowledge gaps in the field. The analysis reveals a clear dominance of work on plankton community structure (81%), whereas topics such as modeling and scenario analysis (7%), ecosystem assessment (7%), and bloom dynamics and seasonality (5%) remain comparatively underrepresented. Post-2020 publications indicate a promising shift toward scenario-based frameworks, gelatinous zooplankton impacts, and trait-based indicators, although functional integration remains fragmented. Keyword co-occurrence and network analyses revealed a concentration on nutrient–phytoplankton–zooplankton pathways, while other themes—such as bioluminescence and redoxcline dynamics—appeared only marginally represented in the literature we analyzed. To support ecosystem-based management under the Marine Strategy Framework Directive (MSFD), we highlight three priorities: improving NPZD-type models, using trophic efficiency metrics, and standardizing plankton indicators across the region. Strengthening the mechanistic understanding of planktonic trophic linkages is critical for improving food web assessments and adaptive marine governance in the Black Sea. Full article

With the purpose of understanding the trophic relationships between three herbivores that use humid high-mountain grassland and evaluating a possible interspecific competition between them and depending on the importance of the hydromorphic vegetation formations of high-mountain areas, relations were established between the attributes of these grasslands and the botanical composition of the diet of grey-breasted seedsnipe (Thinocorus orbignyianus), brown hares (Lepus europaeus), and horses (Equus ferus caballus). For two summer seasons, the botanical composition of the grassland and dry matter availability were assessed. In parallel, the botanical composition of the diets of the three herbivores was estimated through fecal microhistology. Based on the botanical composition data for both the grasslands and herbivores’ diets, their relative diversity was estimated. The Pianka index was established among the three herbivores. Hares showed greater dietary diversity (J) than horses and grey-breasted seedsnipes, factors that were negatively correlated in all three cases with the vegetation diversity patch. The same response amplitude was found when analyzing the food web. The dietary diversity for all species showed no relation to the dry matter productivity of the vegetable patches. Through analyzing the correlation of the abundance of two species of Cyperaceae in the grassland with the presence of the same in the diet of herbivores, we found a negative relationship between the abundance of Carex sp. and grey-breasted seedsnipe diet, and a positive relationship between the Eleocharis pseudoalbibracteata species abundance and frequency in the diet of hares and horses. About the group of species content of graminoids in the diet, a dietary overlap of 30% was determined in the animal species assessed; depending on that, it could identify the existence of interspecific competition between herbivores, which would be conditioned by the response of individuals to the environment. However, and according to the magnitude of the dietary overlap, a low probability of interspecific trophic competition among the studied herbivore species can be expected, which enables the use of the highland wet grassland habitat in sympatry. Full article

The slender snipe eel Nemichthys scolopaceus Richardson, 1848 is cosmopolitan in tropical and temperate seas, inhabiting the mesopelagic and bathypelagic zone between 200 and 1000 m depth. It is known to be an active predator in the DSL (Deep Scattering Layer) and the NBA (Near Bottom Aggregation), feeding mostly on decapod and euphausiid crustaceans, and playing a central role in carbon fluxes through meso- and bathypelagic ecosystems. Despite its potential importance in the deep trophic web ecosystem, the trophic ecology of Nemichthys scolopaceus is not well known. The aim of this study was to start to fill this knowledge gap. A total of 35 specimens of N. scolopaceus caught through bottom trawling in the Mediterranean Sea were analyzed in the laboratory for stomach content composition. As expected, mainly decapod crustaceans were found, in particular Plesionika martia, Pasiphaea multidentata, Funchalia woodwardi, and Robustosergia robusta species. The degree of digestion of prey in the stomachs was high in all cases. Our findings seem to confirm the specialist diet of Nemichthys scolopaceus based on shrimp-like crustaceans. Full article

Bemisia tabaci is a major pest of open-field melons in Mediterranean regions. Combining several species of natural enemies can improve pest control but it can give undesirable results when the species engage in antagonistic interactions. This study evaluated the effectiveness of Deraeocoris serenus, Orius laevigatus, and Eretmocerus eremicus as biological control agents and the interactions among the species. This was assessed with the presence–absence of all three species combined in a full-factorial assay. Each microcosm consisted of a melon plant grown in a 5 L pot enclosed in fine mesh, with each of the eight treatments replicated four times. Whiteflies were counted on three leaves per plant, and natural enemies were counted on the whole plants over six weeks. Basal leaves were taken to the laboratory and observed for the emergence of parasitoids. All three natural enemies independently significantly reduced whitefly numbers. Deraeocoris serenus was the most effective biocontrol agent, achieving whitefly reductions of more than 100-fold compared to the control. In contrast, O. laevigatus and E. eremicus achieved reductions of approximately 2.4-fold and 3.6-fold, respectively. No additive or synergistic effects in whitefly control were observed when two or more natural enemies were combined. Deraeocoris serenus and O. laevigatus were found to engage in mutual antagonistic interactions, and these two predators also interfered with the parasitoid. In addition, E. eremicus was also found to interfere with D. serenus. Understanding such interactions is essential for optimizing the management of natural enemies and improving biological pest control. Full article

In this study, we applied a new technique for vegetatively transplanting kelp Eisenia bicyclis to restore macroalgal habitats. We aimed to assess the restoration success of the E. bicyclis bed by comparing the carbon and nitrogen stable isotope ratios of macrobenthic consumers and their isotopic niches in artificial and control (barren ground) habitats. Except for the deposit feeding group, no significant differences were observed in isotopic values of the other feeding groups (suspension feeders, herbivores, omnivores, and carnivores) between the two sites. In contrast, our results showed wider isotopic niche indices for all feeding groups at the transplantation site compared to those at the control site, suggesting increased trophic diversity in the artificial habitat. Overall, these results indicate that the macroalgal bed created using the new method can play an ecological role in restoring functional properties of food web structures via trophic support of degraded coastal ecosystems. Full article