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Abstract The dugong (Dugong dugon), a large marine mammal herbivore of the Indo-Pacific, is vulnerable to extinction at a global scale due to a combination of human-related threats including habitat degradation. The species forages on seagrass habitats (marine phanerogams) and plays a key role in the functioning and sensitivity of these declining coastal ecosystems. The trophic behaviour and plasticity of dugong populations in response to extrinsic and intrinsic factors are therefore crucial features to both dugong and seagrass conservation. Yet, this knowledge remains limited to few visual observations and analyses of mouth, stomach or faecal contents of stranded individuals. We take advantage of a long-term monitoring of stranded individuals from the endangered New Caledonian population to depict features of dugongs’ trophic ecology from Carbon and Nitrogen stable isotopes. A total of 59 dugong skin samples were used to portrait the stable isotope niche of dugongs according to their sex and maturity. In light of previous work conducted in New Caledonia, a subset of these samples was used to model the trophic mix of dugong males and females. Our stable isotope mixing models used C and N isotope values of 10 taxa bbelonging to five divisions of metazoans, plants, and chromists. Our results represent the first estimate of the species dietary niche in the isotopic space. They suggest that the diet of dugong calves overlaps more with that of adult females (δ13C: − 6.38 ± 1.13 ‰; δ15N: 2.49 ± 1.10 ‰) than males (δ13C: − 5.92 ± 1.10 ‰; δ15N: 3.69 ± 1.28 ‰). Further, we highlight differences in the expected trophic mix of dugong adult males and females. From these, we formulate a sex-specific foraging behaviour hypothesis in dugongs, whereby lactating females could forage over smaller spatial ranges but more diverse food sources thanmales. The study emphasizes the importance of long-term stranding monitoring programs to study the ecology of marine mammals.. Finally, it depicts an ecological feature that may contribute to the sensitivity of vulnerable dugongs to ongoing changes on tropical coastal ecosystems.

This essay analyzes a robust body of C and N stable isotopes from human and animal collagen and plant remains (n = 423) in the area of Lower Yangtze River dating to 8000–4300 cal. BP, combined with new isotopic data recovered from the Zhelin site in Shanghai, to explore the dietary differences between coastal region and the inland core area of the Liangzhu culture (5300–4300 cal. BP). Our findings suggest that the food variety of the peripheral inhabitants of the core area of the Liangzhu culture may became less diverse over time, while at the same time their reliance on a few domesticated species (rice and pigs) increased. It may be a result of the growing economic and cultural influence of the populations in the inland core Liangzhu area. [ABSTRACT FROM AUTHOR]

Landscape fragmentation caused by agricultural expansion directly influences the spatial distribution of habitats and resources, favoring populations of pest insects such as the polyphagous whitefly Bemisia tabaci. Therefore, pest insects may constantly be dispersing between large- and small-scale crops that vary in quality and size at the landscape level. We aimed to understand how habitat use, dispersal movement and population dynamics of B. tabaci occur between large-scale and small-scale crops. We conducted a field experiment in large-scale soybean farms and small-scale farms cropping tomato plants in Brazil for two years. We collected soybean and tomato plant samples and adult whiteflies on these plants at different times of the phenological cycle of the crops. We determined the carbon and nitrogen stable isotope ratios of the plants and the whiteflies collected on these plants. We also estimated the population densities of whiteflies over time on these crops. We found that whitefly populations behave as metapopulations connected by dispersal. The isotopic ratios of B. tabaci revealed that large-scale soybean crops are source habitats of whitefly populations that, after harvest, disperse and redistribute among small-scale tomato farms causing a cascading effect on population growth on the latter. Therefore, understanding the spatial dynamics and management of pests such as whiteflies requires regional strategies, including large-scale and adjacent small-scale crops. C and N stable isotopes used here were able to track pest populations at the landscape level and, therefore, could be helpful to subsidize area-wide pest management strategies of whiteflies. [ABSTRACT FROM AUTHOR]

In salt marshes of the Southeastern USA, purple marsh crabs (Sesarma reticulatum), hereafter Sesarma, aggregate in grazing and burrowing fronts at the heads of tidal creeks, accelerating creek incision into marsh platforms. We explored the effects of this keystone grazer and sediment engineer on salt marsh sediment accumulation, hydrology, and carbon (C) and nitrogen (N) turnover using radionuclides (210Pb and 7Be), total hydrolyzable amino acids (THAA), and C and N stable isotopes (δ13C and δ15N) in sediment from paired Sesarma-grazed and un-grazed creeks. Sesarma-grazed-creek sediments exhibited greater bioturbation and tidal inundation compared to sediments in un-grazed creeks, as indicated by larger 210Pb and 7Be inventories. Total organic carbon (TOC) to total nitrogen (TN) weight ratios (C:N) were higher and δ15N values were lower in grazed-creek sediments than in un-grazed-creek sediments, suggesting Sesarma remove and assimilate N in their tissues, and excrete N with lower δ15N values into sediments. In support of this inference, the percent total carbon (TC) and percent TOC declined by nearly half, percent TN decreased by ~ 80%, and the C:N ratio exhibited a ~ threefold increase between Sesarma fore-gut and hind-gut contents. An estimated 91% of Sesarma's diet was derived from Spartina alterniflora, the region's dominant salt marsh plant. We found that, as Sesarma grazing fronts progress across marsh landscapes, they enhance the decay of Spartina-derived organic matter and prolong marsh tidal inundation. These findings highlight the need to better account for the effects of keystone grazers and sediment engineers, like Sesarma, in estimates of the stability and size of blue C stores in coastal wetlands. [ABSTRACT FROM AUTHOR]

Understanding the relationship between suspended particulate matter (SPM), sediment organic C, N stable isotopes, and lake trophic state index (TSI) is essential for managing lake pollution and eutrophication. According to the δ 13C, δ 15N, and C/N we found that the organic C in SPM and sediment of Caohai Lake primarily originated from macrophytes, while N was sourced from chemical fertilizers, phytoplankton, and aquatic plants. Total nitrogen, total phosphorus, NO3−-N, oxidation reduction potential, and Chl.a were identified as key factors influencing the sources and variations of SPM and sediment organic C and N stable isotopes in Caohai Lake, with a significant linear correlation observed between C, N stable isotopes, and TSI in sediments. To mitigate eutrophication in Caohai Lake, it is recommended that farmers apply fertilizers judiciously to minimize nutrient loss and that aquatic plants be regularly harvested to reduce N release from plant residues. [Display omitted] • Stable isotopes identify sources of C and N in lakes and provide recommendations for eutrophication management. • Consistency of organic C sources in lake suspended particulate matter and sediments • The multiple source pathways of organic N indicate the presence of multiple N pollution pathways in the lake. • There was a significant linear correlation between TSI and sediment C and N stable isotopes. • Reducing exogenous emissions and endogenous releases to control eutrophication in lakes [ABSTRACT FROM AUTHOR]

As global environmental change continues, animals face uncertain habitat availability and quality that influences life cycle phenology and population dynamics. For decades, the population abundance and emergence patterns of burrowing mayflies have been used as a sentinel for water quality changes in large freshwater systems around the world. Despite reduced point source pollutants, evidence is mounting that the interactions among habitat loss, contaminants, and changing climate could be causing declines in mayfly production and shifts in emergence timing. We combined radar observations with traditional field measures to identify changes in mayfly populations from nymph to adult. We studied Hexagenia sp. secondary production in a large reservoir, Lake Seminole, which has contrasting water sources and land use on each arm that could contribute to differences in emergence patterns. We predicted that mayfly secondary production would be higher, and emergence would be earlier in the Chattahoochee arm versus the Flint arm because of differences in available nutrients and temperature. Benthic declines in abundance and biomass followed radar observations of emergence. Mean annual water temperature was similar, with the Flint arm having less seasonal variation. Mayfly growth was similar across the lake, but production was higher in the upper Flint arm, perhaps because of temperature stability, higher nutrient concentrations, and more lotic conditions. The natural abundance of nitrogen‐stable isotopes in mayflies showed distinct patterns between the arms and from nymph to adult. Linking benthic sampling with radar observations verified our capability to track mayfly biomass across the landscape and begin to calibrate previous measures of production with radar‐derived abundance. Coupling radar observations with stable isotope and tissue nutrient measurements allowed us to further quantify the subsidies moving from aquatic to terrestrial ecosystems, setting the framework to examine both historic and future population changes and mayfly contributions to cross‐ecosystem subsidies. [ABSTRACT FROM AUTHOR]

Abstract This essay analyzes a robust body of C and N stable isotopes from human and animal collagen and plant remains (n = 423) in the area of Lower Yangtze River dating to 8000–4300 cal. BP, combined with new isotopic data recovered from the Zhelin site in Shanghai, to explore the dietary differences between coastal region and the inland core area of the Liangzhu culture (5300–4300 cal. BP). Our findings suggest that the food variety of the peripheral inhabitants of the core area of the Liangzhu culture may became less diverse over time, while at the same time their reliance on a few domesticated species (rice and pigs) increased. It may be a result of the growing economic and cultural influence of the populations in the inland core Liangzhu area.

The avian vampire fly is an invasive species on the Galapagos Islands, where its hematophagous larvae utilize nestling birds as hosts. It poses a serious threat to populations and species of Darwin finches and other avian species. Prior studies suggest that the avian vampire fly larvae develop more rapidly in nests of small tree finches compared to sympatric green warbler finch nests. Here we investigate factors that may differentially influence larval growth in the two host species, including nest microclimate and nestling diet. We collected nest base temperature and humidity data as proxies for nest microclimate. As indicators of dietary composition and quality, we measured stable isotope δ13C and δ15N composition of nestling blood, used the C:N ratios as an indicator of relative protein content, and assessed the amino acid composition of the blood. The hematophagous larvae living off nestling blood were analyzed for the same parameters except amino acid composition. The effect of nest base humidity on nest base temperature significantly depended on bird species: at low humidity levels nest base temperature was higher in the small tree finch, and declined in both species as nest base humidity increased, which suggests higher stable heat capacity of small tree finch nests. The effect of age group based on the predicted onset of thermoregulation was marginally significant. Nest base temperatures were significantly higher in small tree finch nests during the predicted female brooding period before fully effective thermoregulation. Stable isotope δ13C levels were significantly higher in the blood of small tree finch nestlings compared to warbler finch nestlings, suggesting a difference in nestling food composition and source, while. δ15N levels were similar. The C:N ratios and amino acid composition of nestling blood were not significantly different between the two species, suggesting similar dietary quality. Thus, the faster development of larvae in small tree finch nests may be due to higher nest base temperatures during the early nestling phase rather than host blood quality parameters. [ABSTRACT FROM AUTHOR]

ABSTRACTMountain lakes are sensitive indicators of anthropogenically driven global change, with lake sediment records documenting increased primary production during the twentieth century. Atmospheric nutrient deposition and warming have been attributed to changes in other Western mountain lakes, however, the intensity of these drivers varies. We analyzed a sediment core representing a 270-year record from Santa Fe Lake, New Mexico, to constrain the southern margin of Rocky Mountain lakes and quantify patterns of change in lake biogeochemistry, production, and diatoms since 1750. Lake sediments were dated using 210Pb and analyzed for carbon (C), nitrogen (N), stable isotopes (δ13C, δ15N), diatoms, and phototrophic pigments. The abundance of cyanobacteria, purple sulfur-reducing bacteria, and diatom pigments were elevated during the stable conditions of the Little Ice Age; these phototrophic groups declined in the late 1800s and reached a minimum by 1950. From 1950 to 2020, sediments recorded an increased abundance of cryptophyte, diatom, and chlorophyte groups. The C and N (percentage dry mass) increased after 1950, whereas δ15N and δ13C values declined. Changes since the mid-twentieth century are contemporaneous with warming trends in the Southwest and modest deposition of atmospheric N. Our findings highlight the geographic variability of mountain lake responses to changing environmental conditions.

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Invasive species are often generalists that can take advantage of formerly unexploited resources. The existence of such vacant niches is more likely in species-poor systems like the Baltic Sea. The suspension feeding wedge clam, Rangia cuneata, native to estuarine environments in the Gulf of Mexico, was sighted for the first time in the southeastern Baltic in 2010 and a few years later in the northern Baltic along the Swedish coast. To explore possible competition for food resources between R. cuneata and the three native clams inhabiting Baltic shallow soft bottoms, stable isotope and fatty acid analyses were conducted. There was no overlap between R. cuneata and any of the native species in either stable isotope or fatty acid niches. This suggests efficient partitioning of resources; multivariate analyses indicate that separation was driven mainly by δ13C and by fatty acids reflecting diatoms and cyanobacteria, respectively (e.g. 16:1ω7 and 18:3ω3). R. cuneata reflected seasonal variation in phytoplankton more than other clams reflecting higher trophic plasticity. In conclusion, the addition of R. cuneata to the Baltic shallow soft bottoms suggests the existence of a vacant trophic niche in these sediment habitats, however the long-term effects on other species and nutrient cycling requires further studies focusing on the population dynamics of R. cuneata and its impact on the Baltic Sea ecosystem. [ABSTRACT FROM AUTHOR]

The discovery of cyclonic and dipole eddies in the Mozambique Channel (MC) indicates that the understanding of the mesoscale eddy characteristics in the MC is incomplete. The distributions of anticyclonic, cyclonic, and dipole eddies along the MC were elucidated in this study using satellite observations. It was observed that these eddies exhibit a preference for emergence and movement in the western MC. The occurrence frequencies of anticyclonic and cyclonic eddies are four and three times per year, respectively, in the narrowest section of the MC. In contrast, the frequency of mesoscale eddies reaches its peak at nine times per year in the central region of the MC. The occurrence of dipole eddies also reaches its peak twice per year in the middle MC. Dipole eddies are more prevalent in the MC and exhibit larger dimensions and shorter lifespans compared to anticyclonic and cyclonic eddies. Mesoscale eddies, which traverse the narrowest section of the MC and propagate southward, are predominantly generated within the western Comoros Basin due to barotropic instability. The southward branch of the Northeast Madagascar Current (NEMC) plays a crucial role in transporting these eddies to the middle MC. The eastern middle MC is also a generation site for mesoscale eddies in addition to the Comoros Basin, where cyclonic eddies are generated twice per year. These cyclonic eddies are also generated due to barotropic instability. [ABSTRACT FROM AUTHOR]

East Asia, being the evolutionary center of Coelodonta, offers a unique opportunity to explore the spatiotemporal paleoecologies of this genus. This study utilized bulk and serial stable carbon and oxygen isotope analyses on the Coelodonta nihowanensis and other ungulates from the Longdan fauna as well as two modern goats in the Linxia Basin, aiming to explore the paleoecology of C. nihowanensis at the periphery of the Tibetan Plateau during the Early Pleistocene. The isotopic results of these mammals indicated that C3 vegetation was possibly a major component of the local environment in the Linxia Basin, which was influenced by a seasonal summer monsoon. C. nihowanensis specimens in the Longdan fauna were possibly mixed feeders, as indicated by the wide distribution of their δ13C values and the intermediate δ18O values compared to other coexisting ungulates. Moreover, the comparison of the δ13C and δ18O values of similar taxa from the Linxia and Nihewan basins has revealed spatiotemporal differences in the paleoclimate and paleoenvironments of these two regions throughout the Early Pleistocene. This provides a holistic framework for understanding the paleoecology of the C. nihowanensis. The isotopic results of the C. nihowanensis in the Linxia and Nihewan basins suggested varied foraging ecologies across different sites and time spans during the Early Pleistocene. This underscores the adaptability of the C. nihowanensis to diverse environments from west to east in northern China. By scrutinizing the evolutionary ecological history of the woolly rhinoceroses from its ancestor, Coelodonta thibetana, to its final form, Coelodonta antiquitatis, this study sheds light on the ecological adaptation of this genus from the Pliocene to Late Pleistocene, spanning its migration from the Tibetan Plateau to northern Eurasia. [ABSTRACT FROM AUTHOR]

Guizhou is one of the most important black tea producing areas in China. The purpose of this study was to explore the characteristic flavor compounds of Guizhou black tea and investigate the influence of environmental factors on the formation of black tea flavor components. In this study, HS-GC-IMS was used to identify 143 compounds from black tea samples. OPLS-DA was employed to analyze the data, effectively distinguishing black tea from different origins. A total of 83 significant flavor compounds were selected as potential markers using the VIP variable selection method and OAV screening. Cluster analysis was used to identify the characteristic flavor compounds in black tea samples from different origins. In addition, by investigating the climate environment of various production regions and analyzing the volatile components along with stable C and N isotope ratios of samples, it was discovered that the development of volatile components in black tea could be significantly influenced by ambient temperature and light. In regions with higher temperatures, the concentration of volatile components with floral, fruity, and sweet aromas is higher, resulting in a more intense aroma in black tea. In regions with low ambient temperatures but strong sunlight, black tea contains higher levels of components that give it a fresh and nutty aroma. As a result, the aroma of black tea is relatively elegant and fresh. At the same time, it was found that the stable isotope ratios of C and N in black tea were also significantly affected by ambient temperature and were positively correlated. This study introduces a fresh perspective for the comprehensive examination of Guizhou black tea, offering theoretical guidance for optimizing planting conditions and enhancing product quality. Its positive influence on promoting the development of the Guizhou black tea industry is noteworthy. [ABSTRACT FROM AUTHOR]

Rationale: Hair is known to preserve diet history and other physiological information during its growth period and is often used in chemical analyses. However, the growth patterns and turnover of hair vary according to the animal species or habitat, so understanding these patterns in the target animal is necessary for interpreting the results of hair analyses. In this study, we aimed to elucidate the growth pattern and dietary information of winter coat hair in captive sika deer (Cervus nippon)., Methods: Experiments involving hair-staining and shaving were conducted to elucidate the growth pattern of sika deer hair. A diet-switching experiment was conducted to ascertain what dietary information is reflected in the carbon and nitrogen stable isotope values of the deer winter coat. Hair samples collected from each body site (head, shoulder, back, and hip) were analyzed using an elemental analyser interfaced with an isotope-ratio mass spectrometer., Results: The winter coat grows from early September to early November, and then stops after that. During the growth period of the winter coat, the hair of the shoulder and back grew at a constant rate. The carbon and nitrogen stable isotope values of hair reflected the deer's feeding history during hair growth, but there seemed to be a time lag in the hip hair., Conclusions: The results suggest that the guard hair of the shoulder is suitable for hair analysis in sika deer. The obtained information on growth patterns and isotopic change of hair from captive sika deer according to diet be useful for interpreting the results of future analyses using hair samples of wild deer., (© 2024 John Wiley & Sons Ltd.)

Coastal habitats are crucial for supporting ecological processes and serve as vital ecosystems for diverse fish species, providing essential functions such as feeding, nursery provision, and reproductive habitats. Fish communities are ecologically important components of coastal ecosystems and are affected by multiple environmental factors. Despite their importance, determining the effects of environmental factors on seasonal variations in fish species diversity and community dynamics remains a challenge. The advent of environmental DNA (eDNA) technology, an environmentally conscious approach, has resulted in considerable advancements in recent years and has been progressively adopted for marine fish population monitoring. Here, we used environmental DNA metabarcoding to study seasonal variations in fish community structure on a coastal island, and we assessed the effects of environmental factors in structuring these communities. Our findings revealed a rich diversity of 72 fish species across 40 families and 23 orders in the seawater surrounding an island of the Seto Inland Sea (SIS), Western Japan. Notably, the composition of fish communities varied significantly between seasons, with seawater temperature, salinity, and dissolved inorganic phosphorus (DIP) concentration identified as important factors correlated with fish communities' structures. In conclusion, our study provides useful information of fish diversity, and we suggest that eDNA is a valuable technique for monitoring fish diversity in coastal areas. These findings are crucial for ecological studies and the environmental monitoring of oceanic coastal environments. [ABSTRACT FROM AUTHOR]

Pu-erh tea is a famous tea worldwide, and identification of the geographical origin of Pu-erh tea can not only protect manufacture's interests, but also boost consumers' confidence. However, tree age may also influence the fingerprints of Pu-erh tea. In order to study the effects of the geographical origin and tree age on the interactions of stable isotopes and multi-elements of Pu-erh tea, 53 Pu-erh tea leaves with three different age stages from three different areas in Yunnan were collected in 2023. The δ13C, δ15N values and 25 elements were determined and analyzed. The results showed that δ13C, δ15N, Mg, Mn, Fe, Cu, Zn, Rb, Sr, Y, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu had significant differences among different geographical origins (p < 0.05). Mn content was significantly influenced by region and tree age interaction. Based on multi-way analysis of variance, principal component analysis and step-wised discriminant analysis, 24 parameters were found to be closely related to the geographical origin rather than tree age, and the geographical origin of Pu-erh tea can be 100.0% discriminated in cross-validation with six parameters (δ13C, δ15N, Mn, Mg, La, and Tb). The study could provide references for the establishment of a database for the traceability of Pu-erh tea, and even the identification of tea sample regions with different tree ages. [ABSTRACT FROM AUTHOR]

Following the development of modern genome sequencing technologies, the investigation of museum osteological finds is increasingly informative and popular. Viable protocols to help preserve these collections from exceedingly invasive analyses, would allow greater access to the specimens for scientific research. The main aim of this work is to survey skeletal tissues, specifically petrous bones and roots of teeth, using infrared spectroscopy as a prescreening method to assess the bone quality for molecular analyses. This approach could overcome the major problem of identifying useful genetic material in archaeological bone collections without resorting to demanding, time consuming and expensive laboratory studies. A minimally invasive sampling of archaeological bones was developed and bone structural and compositional changes were examined, linking isotopic and genetic data to infrared spectra. The predictive model based on Infrared parameters is effective in determining the occurrence of ancient DNA (aDNA); however, the quality/quantity of aDNA cannot be determined because of the influence of environmental and local factors experienced by the examined bones during the burial period. [ABSTRACT FROM AUTHOR]

Supplemental feed for free‐ranging deer is often advocated by managers to compensate for winter survival. However, providing extra food has great costs so it is important to know how essential supplemental feed is for deer populations. In our study, supplemental feed is supplied year round for free‐ranging Père David's deer Elaphurus davidianus since early 2019 to help them survive food shortages in the Jiangsu Dafeng Milu National Nature Reserve. To understand use of supplemental feed, we quantified the biomass contributions of C3 plants, C4 plants and supplemental feed consumed by free‐ranging deer by assessing their faecal carbon and nitrogen stable isotope values in May, July, October and December. The diet–faeces trophic shift of deer was assessed using semi‐captive animals. Faeces in both areas were collected and faecal δ13C values revealed more variable diets of free‐ranging deer than semi‐captive deer in different months. MixSIAR model showed that C4 plants contributed greatly to deer diet biomass (75.1, 82, 64.3, 79.4%, respectively in May, July, October and December) compared with C3 plants and supplemental feed. We suggest that managers should consider the efficiency of long‐term supplemental feed and consider the selection of C3 and C4 plants during restoration. [ABSTRACT FROM AUTHOR]

Recent droughts have strongly impacted forest ecosystems and are projected to increase in frequency, intensity, and duration in the future together with continued warming. While evidence suggests that tree diversity can regulate drought impacts in natural forests, few studies examine whether mixed tree plantations are more resistant to the impacts of severe droughts. Using natural variations in leaf carbon (C) and nitrogen (N) isotopic ratios, that is δ 13 C and δ 15 N, as proxies for drought response, we analyzed the effects of tree species richness on the functional responses of tree plantations to the pan-European 2018 summer drought in seven European tree diversity experiments. We found that leaf δ 13 C decreased with increasing tree species richness, indicating less drought stress. This effect was not related to drought intensity, nor desiccation tolerance of the tree species. Leaf δ 15 N increased with drought intensity, indicating a shift toward more open N cycling as water availability diminishes. Additionally, drought intensity was observed to alter the influence of tree species richness on leaf δ 15 N from weakly negative under low drought intensity to weakly positive under high drought intensity. Overall, our findings suggest that dual leaf isotope analysis helps understand the interaction between drought, nutrients, and species richness., (© 2024 The Authors. New Phytologist © 2024 New Phytologist Foundation.)

Streptomyces is a drought-tolerant bacterial genus in soils, which forms close associations with plants to provide host resilience to drought stress. Here we synthesize the emerging research that illuminates the multifaceted interactions of Streptomyces spp. in both plant and soil environments. It also explores the potential co-evolutionary relationship between plants and Streptomyces spp. to forge mutualistic relationships, providing drought tolerance to plants. We propose that further advancement in fundamental knowledge of eco-evolutionary interactions between plants and Streptomyces spp. is crucial and holds substantial promise for developing effective strategies to combat drought stress, ensuring sustainable agriculture and environmental sustainability in the face of climate change., (© 2024. Springer Nature Limited.)

This work intends to identify pollution sources along the margins of Guanabara Bay (GB; SE Brazil) through a multiproxy approach and Bayesian stable isotopic mixture model (BSIMM). For this purpose, 33 surface sediment samples were collected and analyzed for granulometry, geochemistry (heavy metals, total organic carbon-TOC, stable isotopes of carbon and nitrogen-δ 13 C and δ 15 N, Rock-Eval pyrolysis parameters-REPP), and physicochemical parameters. Metal concentrations (E) dissolved in water (E W ), adsorbed by organic matter (E OM ) and by Mn hydroxides (E Mn ), and total extracted concentrations (E T ) were analyzed. Sampling was conducted in 2018 after an oil spill from Reduc Oil Refinery. Potential Ecological risk index (PERI), based on metals, classified 85% of the analyzed stations as having moderate to considerable ecological risk. The metals with the potential to cause the highest ecological risk were Cd W , Cd OM , Pb OM , and Hg OM . The combination of BSIMM and REPP data was an effective proxy for oil spill detection by indicating the presence of polycyclic aromatic hydrocarbons (PAHs). Relatively high TOC contents suggested that the analyzed stations are eutrophicated environments. BSIMM discriminated three groups of stations with different sources of organic matter (OM), endorsing the result previously shown by the cluster analysis: (A) Niterói region, Botafogo marina, Glória marina, Fiscal and Fundão islands with diffuse sources of OM, including marine phytoplankton and material of continental origin from highly polluted rivers and domestic sewage; (B) region near Fundão and Governador islands and Mangue Channel outlet with OM (≃70%) supplied by highly polluted streams and a small contribution of PAHs; (C) Duque de Caxias and Botafogo-Urca inlet with significant contributions of PAHs, materials from C-3 plants and rivers polluted by urban sewage. Results of linear regressions in conjunction with BSIMM indicate that Hg Mn and Pb OM mainly affect Group A's stations. Although the eastern margin of GB (Niterói; Group A) showed greater oceanic interaction than the other groups, it presented substantial concentrations of metals, potentially harmful (i.e., Hg and Pb) to marine biota and human health., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)