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We investigated trophic structures in rocky subtidal ecosystems transitioning from canopy-forming to barren states across coastlines with varying oceanographic conditions. We examined stable isotopes and functional traits of common invertebrate and fish taxa to understand the food-web consequences. We hypothesized that resource exploitation patterns of functional guilds would result in distinct isotopic niches, defining trophic diversity and niche. δ 13 C and δ 15 N ranges of invertebrate functional groups differentiated pelagic from benthic trophic pathways, reflecting flexible dietary use in the absence of macroalgae. Fish production relied on prey using pelagic and benthic basal resources. Trophic redundancy among consumers within functional guilds contributed to intrinsic trophic structure in barren ecosystems. The resulting community-wide trophic diversity has led to consistent niche widths and overlapping niche space. Overall, our findings highlight the crucial roles of consumers that persist with diverse functional guilds in conferring the adaptability of barren rocky ecosystems following habitat disturbance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

We employed Fourier infrared spectroscopy, laser infrared technology, and stable isotope analysis to investigate the relationships between characteristics of ingested plastics and size-related feeding ecology of a mesopelagic predator, longnose lancetfish Alepisaurus ferox. Plastics were detected in 81.48 % of specimens, up to 8.81 ± 8.29 items/individual and 0.59 ± 0.66 items/g wet weight of intestine, and were sized 20.00 μm to 6.50 cm. The majority were granules and fragments in shape, and polystyrene and acrylate copolymer in polymer type. The diversity indices exhibited a correlation with trophic position and body size groups, emphasizing that the ontogenetic dietary shift of A. ferox may influence the diversity of plastics ingested. This study provides new insights into the plastic pathways linking epipelagic and mesopelagic food webs and demonstrates that biochemical ecological tracers can effectively indicate the bioavailability of plastic correlated with growth in mesopelagic predator., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Agricultural nitrogen (N) contributes a dominant percentage to global N pollution in the coastal zone. Emerging research on N isotopes in bivalve shells has shown value for reconstructing historical increases in estuarine wastewater inputs. However, applications for fertilizer N are understudied. Here, we integrate the study of organic N isotopes, in concert with δ 18 O and δ 13 C, in estuarine bivalve shells to investigate spatial and long-term changes in nitrogen inputs and sources. Modern, museum-collected, and subfossil specimens of the genera Mytilus and Ostrea were profiled in a California estuary with an intensely agricultural watershed. Spatial patterns in bivalve isotopic composition reflected gradients in watershed nutrient inputs and productivity parameters. Furthermore, a comparison between modern and historical periods revealed changes in nutrient source or processing over the last 1,000 years. The N isotope values from shells offer perspective on agricultural pollution in estuaries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Macroalgal nitrogen isotope analysis (δ 15 N) is a reliable method for the identification of nitrogen pollutant sources. Understanding δ 15 N geospatial variation within small bays and/or harbour environments can help identify point sources of nitrogen pollution. This study sampled over 300 Fucus vesiculosus and Ulva sp. specimens in September 2022 and May 2023 from Staithes Harbour, North Yorkshire, England. δ 15 N values for Staithes Beck were elevated when compared to sites in Staithes Harbour and the North Sea: this is attributed to sewage effluent and/or agricultural manure. Few sites within Staithes Harbour were significantly different from one another in terms of δ 15 N, suggesting a relatively homogenous nitrogen isotope record of the harbour. Simple harbour environments like Staithes may be relatively well mixed, and thus, sampling one harbour site may be enough to represent the entire harbour. Of course, more complex harbours may require more sample locations to ascertain point sources and mixing in the harbour., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

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 13 C, δ 15 N, 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Limpets are a key taxon regulating the benthic community structure and serving as prey for various predators in rocky shores, however, their role in food web dynamics is still unclear. To determine environmental factors influencing the limpet diet, carbon and nitrogen stable isotopes in limpets and food sources were analyzed on three different coastal habitats. Sediment organic matter contributed the most (86 %) to the limpet diet in bedrocks around tidal flats with abundant sediment supply from the terrestrial matter inflow and the sediment resuspension. Microphytobenthos and macroalgae were the main food sources (57 % and 20 %, respectively) for the limpets around beaches, where benthic flora was abundant. Limpets in bedrocks, erosional habitat, primarily consumed relatively abundant phytoplankton (33 %) and microphytobenthos (28 %). Contrary to previous studies, habitat type, rather than latitude or seawater characteristics, was the most important factor determining the limpet diet. This result also suggests that limpets are non-selective scraper that consume abundant food sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Procellariiform seabirds can accumulate high levels of plastic in their gastrointestinal tracts, which can cause physical damage and potentially provides a contamination route for trace elements. We examined plastic ingestion and trace element contamination of fledgling Manx shearwaters Puffinus puffinus that were harvested for human consumption in 2003 and 2018 on Skúvoy, Faroe Islands (North Atlantic Ocean). Overall, 88% of fledglings contained plastic in their gastrointestinal tracts, with a mean (± SD) of 7.2 ± 6.6 items weighing 0.007 ± 0.016 g. Though the incidence was similar, fledglings ingested significantly more plastic in 2018 compared to 2003. Hepatic trace element concentrations were unrelated to plastic ingestion. Hepatic carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope values were significantly lower in birds sampled in 2018 versus 2003, potentially reflecting further offshore feeding at lower trophic levels. Future research is needed to understand the extent of plastic ingestion by Faroe Islands seabirds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Anthropogenic input of excess nutrients stimulates massive nitrous oxide (N 2 O) production in estuaries with distinct seasonal variations. Here, nitrogen isotopic and isotopomeric signatures were utilized to investigate the seasonal dynamics of N 2 O production and nitrification at the middle reach of the eutrophic Pearl River Estuary in the south of China. Elevated N 2 O production primarily via ammonia oxidation (> 1 nM-N d -1 ) occurred from April to November, along with increased temperature and decreased dissolved oxygen concentration. This consistently oxygenated water column showed active denitrification, contributing 20-40 % to N 2 O production. The water column microbial N 2 O production generally constituted a minor fraction (10-15 %) of the estuarine water-air interface efflux, suggesting that upstream transport and tidal dilution regulated the dissolved N 2 O inventory in the middle reach of the estuary. Nitrification (up to 3000 nM-N d -1 ) played a critical role in bioavailable nitrogen conversion and N 2 O production, albeit with N 2 O yields below 0.05 %., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This paper reports the first record of total mercury (THg) concentrations in albacore (Thunnus alalunga), one of the main tuna species caught from the Western Equatorial Atlantic Ocean and presents a preliminary comparison with other regions and tuna species. Mean, standard deviation and range of concentrations in T. alalunga (515 ± 145 ng g -1 ww; 294-930 ng g -1 ww) with 92 % being of methyl-Hg, are higher than in albacore from other Atlantic Ocean subregions despite their smaller body size. These concentrations are similar to those from the Pacific and Indian oceans, but lower than in the Mediterranean. Compared to other sympatric tuna species, concentrations are higher than those in T. albacares and similar to T. obesus. These results are discussed considering the potential differences in stable isotope values ( 13 C and 15 N) of T. alalunga populations from multiple oceanic areas and compared to other tuna species worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. All data used in this paper is available as supplementary material., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Human activity has led to increased concentrations of mercury (Hg) in the world's oceans. Mercury can bioaccumulate and biomagnify in animal tissues via trophic transfer, thus, becoming most pronounced in larger and older predators. Here, we measured Hg concentrations and their relationship with stable isotopes-based proxies of trophic level (δ 13 C and δ 15 N values) in multiple tissues of Mustelus spp. from the Mediterranean Sea. We found higher Hg concentrations in muscle than in liver and fin tissues. The relationship between Hg concentrations and δ 15 N values in muscle suggested repeated foraging for low trophic level and Hg-poor prey, and biomagnification of Hg at higher trophic levels. Seasonal variations in δ 13 C values could indicate shifts in primary production sources and/or in local prey availability. The HBV Se index suggested no risk to human health, however the safe meal limit recommendations are 4.5 and 2.2 portions per month for adults and children, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To assess the impact of sand mining on resource utilization by the red seabream (Pagrus major) and the trophic structure of fish assemblages two years after mining activities, we compared stable isotope ratios (δ 13 C and δ 15 N) and isotopic niches between aggregated mining and control sites in April and August 2022. Our results showed no spatial differences in the δ 13 C and δ 15 N values of red seabream between the sand mining and control sites, suggesting that the mining did not affect their dietary resources. Furthermore, the considerable overlap among fish consumers suggested that the fish food web in mining areas has trophic functions similar to those in natural habitats after mining activities. Overall, our study enhances our understanding of ecosystem conservation and the ecological-based management of coastal areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The supply and sources of N and Hg in the Geum estuary of the western coast of Korea were evaluated. Triple isotope proxies (δ 15 N NO3 , Δ 17 O NO3 and δ 18 O NO3 ) of NO 3 - combined with conservative mixing between river and ocean waters were used to improve isotope finger-printing methods. The N pool in the Geum estuary was primarily influenced by the Yellow Sea water, followed by riverine discharge (821 × 10 6  mol yr -1 ) and atmospheric deposition (51 × 10 6  mol yr -1 ). The influence of the river was found to be greater for Hg than that of the atmosphere. The triple isotope proxies revealed that the riverine and atmospheric inputs of N have been affected by septic wastes and fossil fuel burning, respectively. From the inner estuary towards offshore region, the influence of the river diminishes, thus increasing the relative impact of the atmosphere. Moreover, the isotope proxies showed a significant influence of N assimilation in February and nitrification in May., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests related to personal relationships that could have influenced the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

Anthropogenic nitrate (NO 3 - ) production has been increasing and is exported to the ocean via river networks, causing eutrophication and ecological damage. While studies have focused on river NO 3 - pollution, what has been lacking is the quantification of the sources of NO 3 - in coastal rivers. This study applied the dual isotopes (δ 15 N/δ 18 O-NO 3 - ) to quantify the sources and their fluxes of NO 3 - in two inflow rivers of the Qinzhou Bay. By adding our results to the NO 3 - source apportionment in Qinzhou Bay, we, for the first time, established the NO 3 - budgets of the terrestrial-to-marine continuum in both high- and low-flow seasons. We quantitatively showed the direct and indirect roles (e.g., the stimulation of nitrification by sewage ammonium-NH 4 + ) of terrestrial sources in driving the high NO 3 - loading in the estuary. The results highlighted the necessity to consider coastal rivers and estuary as a whole, which could shed light on the effective reduction of NO 3 - pollution in coastal environments., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Boat Harbour, Nova Scotia was a tidal estuary that was converted into a wastewater treatment facility for pulp mill effluent in 1967. Treated effluent from Boat Harbour was discharged into the coastal Northumberland Strait, contributing significant nutrient and freshwater inputs into the coastal environment, potentially impacting local biogeochemistry and ecosystem structure. This study used stable isotope analysis of carbon (δ 13 C) and nitrogen (δ 15 N) of representative taxa to assess spatial variability in nutrient sources and trophic dynamics. Results identified stable isotope variation with depleted δ 13 C and δ 15 N values in taxa near Boat Harbour. Blue mussel (Mytilus edulis) and mummichog (Fundulus heteroclitus) were the most suitable bioindicators for identifying variation in nutrient sources. Stable isotope signatures in this study may be reflective of residual pulp mill effluent-derived nutrients, differences in marine versus terrestrial nutrient sources, and a pronounced coastal salinity gradient. The present study defined the baseline nutrient conditions of the Northumberland Strait and will be useful in assessing the effectiveness of remediation activities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Most anthropogenic nitrogen (N) reaches coastal waters via rivers carrying increasing loads of sewage, fertilizer, and sediments. To understand anthropogenic N impacts, we need to understand historical N-dynamics before human influence. Stable isotope ratios of N preserved in carbonates are one way to create temporal N records. However, records that span periods of human occupation are scarce, limiting our ability to contextualize modern N dynamics. Here, we produce a fossil-bound N-record using coral subfossils, spanning 6700 years in China's Greater Bay Area (GBA). We found that during the mid-to-late Holocene, the GBA's coastal N was dominated by fluvial sources. The weakening of the Asia monsoon throughout the late-Holocene decreased river outflow, leading to a relative increase of marine nitrate. This source shift from riverine-to-ocean dominance was overprinted by anthropogenic N. During the late 1980s to early 1990s, human development and associated effluent inundated the coastal system, contributing to the decline of coral communities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Untreated sewage discharged increases the nutrient loads and changes ecosystem functions. It increases the values of the nitrogen isotopic signature (δ 15 N) of primary producers such as seagrasses. Itaparica Island (Bahia, Brazil) has undergone extensive urbanization over 50 years. Most of the island has no sewage treatment, and a bridge's construction could increase its population ten times. We evaluated the effects of sewage inputs on the δ 15 N of seagrass (Halodule wrightii) across Itaparica Island in 14 areas of the island with different degrees of urbanization. Average values of δ 15 N ranged from -3.95 ‰ (±1.04 SD) to 2.73 ‰ (±1.61). The highest human occupation site also has the highest mean value of δ 15 N, and seagrass shoot density. The significant correlation (p < 0.05) between δ 15 N values and shoot density may indicate a possible anthropogenic pressure impacting meadow abundance. Despite a positive correlation, increased anthropogenic nutrient supply can support algae growth and harm seagrass ecosystems., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Matheus Fernandes Andrade reports equipment, drugs, or supplies and travel were provided by National Council for Scientific and Technological Development. Matheus Fernandes Andrade reports financial support was provided by Foundation for Research Support of Bahia State. Ana Cecilia Rizzatti de Albergaria Barbosa reports financial support was provided by National Council for Scientific and Technological Development. Vinicius Faria Patire reports financial support was provided by Coordination of Higher Education Personnel Improvement., (Copyright © 2023. Published by Elsevier Ltd.)

In this study, we assessed spatial and temporal variations in the trophic structure of fish assemblages in the Yellow Sea during spring and summer 2022 and compared their isotopic niches between the Provisional Measure Zone (PMZ) and Korea's west areas (non-PMZ) within the Yellow Sea. Spatial and temporal differences in the diversity and dominant species of fish assemblages were found between the PMZ and non-PMZ areas between the seasons. The mean δ 13 C values of fish assemblages were relatively higher in the non-PMZ areas than in the PMZ areas. In contrast, no significant differences were found in the mean δ 15 N values between the areas. Generally, the isotopic niche indices were relatively narrow in the PMZ areas compared to those in the non-PMZ areas. Overall, these spatial differences between the PMZ and non-PMZ areas suggest different trophic diversity of fish assemblages, resulting from site-specific variations in environmental conditions and community composition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

To assess the basal resources supporting food webs impacted by rainfalls, we compared stable isotope ratios (δ 13 C and δ 15 N) of fish consumers and organic matter sources between up- and down-sites in an estuary between seasons (June and September) and years (2018 and 2019) that showed different patterns of summer monsoon. Our study showed seasonal differences in the δ 13 C and δ 15 N values of basal resources and fish consumers in both years. At the up-site, significant differences of δ 13 C values of fish consumers were found between years, resulting from changing rainfall period, thereby causing a shift in food availability from terrigenous organic matter to periphyton. In contrast, at the down-site, the consistent isotopic values of fishes were observed in both years, suggesting that rainfall shift has a negligible impact on resources for fishes. Overall, the annual shift in resources for fishes in the estuary may be controlled by contrasting rainfall events., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The mitigation of eutrophication in the Pearl River Estuary (PRE) has encountered numerous challenges in regards to source control. Herein, the isotope mixing model (SIAR) was used to quantify the primary nitrate sources in the PRE. The results showed that the nitrate levels were significantly higher in the high-flow season than in the low-flow season. Meanwhile, we found the most important nitrate sources were manure and sewage during the high-flow season, with a contribution ratio of 47 % in the low salt area (LSA) and 29 % in the high salt area (HSA). During the low-flow season, the primary nitrate sources were identified as reduced nitrogen fertilizer in the LSA and manure and sewage in the HSA, which accounted for 52 % and 44 %, respectively. Furthermore, we also suggest that a feasible measure might be to control the pollution caused in the PRE by manure and sewage as well as reduced nitrogen fertilizer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Increased coastal urbanization worldwide has resulted in increased nitrogen inputs to ecosystems, leading to eutrophication and other negative effects. We assessed δ 15 N in the dead-collected shells of three molluscan species in two estuaries in order to evaluate their ability to identify known gradients in wastewater nitrogen input, namely from private septic systems feeding directly into Waquoit Bay and from a groundwater plume reflecting wastewater injection at a municipal treatment plant in West Falmouth Harbor, Massachusetts, USA. Shells of a suspension-feeder (Geukensia demissa), a micro-algal grazer (Littorina littorea), and an omnivore (Nassarius obsoletus) were collected from lower intertidal sediments near the taxon's life habitat. We found that δ 15 N in dead-collected shells decreased significantly along the gradients of wastewater pollution in both estuaries, with similar results across all three trophic groups. These positive results demonstrate the potential of dead-shell assemblages for detecting spatial gradients of wastewater pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Collected sediment samples from the cage fish farm were measured to determine carbon and nitrogen stable isotope compositions and to understand the influence of the aquaculture waste on the sediment. The average δ 13 C of the sediment organic matter was -27.2 ‰ and -26.5 ‰, and the average δ 15 N value was 5.6 ‰ and 6.2 ‰ in October 2017 and November 2018, respectively. A linear mixing model was used to calculate the contribution ratios of the aquaculture waste in sediment organic matter. The contribution ratio of fish feces was 53.9 % and 25.5 %, and the contribution ratio of waste feed was 18.4 % and 52.6 % in October 2017 and November 2018, respectively. The sediment in the "cage fish area" was characterized by high waste feed ratio in sediment organic matter. The sediment organic matter was affected by the aquaculture waste even at sites 1500 m away from the cage fish farm., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

To evaluate the impact of bottom aquaculture on benthic ecosystems, characteristics of benthic food web were studied using stable isotope techniques during four seasons in a Manila clam (Ruditapes philippinarum) bottom aquaculture area in a semi-enclosed bay, China. Results showed that although nitrogen stable isotope values of food sources (particulate organic matter and phytoplankton) had significant seasonal differences, there were no significant seasonal changes for benthic food web structure. Manila clam bottom aquaculture can enhance the secondary productivity and improve the basic trophic pathways by providing bio-deposits. Besides particulate organic matter and phytoplankton, Manila clam could feed on self-generated feces with high nitrogen stable isotope values, and benthic micro- and macroalga with high carbon stable isotope values. Secondary productivity of the stations with a high degree of aquaculture was higher than that of stations with a low degree. Bivalve bottom culture may have a positive impact on benthic ecosystem functioning., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Assessing mercury (Hg) biomagnification requires the description of prey-predator relationships, for each species and ecosystem, usually based on carbon and nitrogen isotope analyses. Here, we analyzed two seabirds from the Humboldt Current ecosystem, the Guanay cormorant (Phalacrocorax bougainvillii) and the Peruvian booby (Sula variegata), as well as their main prey, the Peruvian anchovy (Engraulis ringens). We reported Hg concentrations, Hg biomagnification (BMF) and isotopic discrimination factors (Δ 13 C and Δ 15 N) in seabird whole blood. BMFs and Δ 13 C in our study (on wild birds where diet was not controlled) were similar to other piscivorous seabirds previously studied in captive settings, but Δ 15 N were lower than most captive experiments. We observed lower Hg concentrations in Humboldt seabirds compared to other oligotrophic ecosystems, possibly due to Hg biodilution in the high biomass of the first trophic levels. This work calls for a better characterization of Hg trophic dynamics in productive upwelling ecosystems., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Coastal lagoons are essential nursery habitats of many marine fishes, but they are often sites of intense human activities that impact water quality and potentially the fish using these habitats. We compared the variability in nutrient uptake (using δ 15 N and δ 13 C) and total mercury (THg) levels in juveniles and adults of three common species in two lagoons on the central Mexican coast of the Pacific Ocean during the wet and dry seasons. One of three species, Achirus mazatlanus had higher THg, δ 15 N, and δ 13 C levels in the lagoon with the greatest wastewater inputs (Barra de Navidad). Delta 13 C varied seasonally for all three species and THg was higher in the dry season for Lutjanus argentiventris and in males of A. mazatlanus. Our results demonstrate that mercury and stable isotopes can identify impacts of human activities on estuarine ichthyofauna and the importance of understanding seasonal and spatial variability of measures that could impact monitoring and predictions of impacts in these lagoons., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Rapa Nui is an important hotspot of endemic marine biodiversity, where diffuse land-based sources (e.g., nutrients and organic matter) entering into coastal waters could develop eutrophication in coastal environments, with deleterious impacts on the marine ecosystem. Stable isotopes (δ 13 C and δ 15 N) of intertidal communities (macroalgae and invertebrates) were studied from sites with contrasting human influence (populated and unpopulated), to evaluate the incorporation and transfer of diffuse land-based sources through food webs. Macroalgae showed differences between some sites, and invertebrates showed a 15 N-enrichment pattern at populated areas relative to unpopulated, being these differences significant in gastropods, barnacles and sea urchins. Moreover, trophic structure metrics suggest a higher trophic diversity in populated areas relative to unpopulated and support the isotopic partitioning between sites, associated with the incorporation of sources with 15 N-enriched values. The above suggests that diffuse land-based sources could be incorporated by macroalgae, transferred into benthic consumers, and altering the trophic structure., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The dynamics of contaminants, such as mercury (Hg), in marine trophic webs is a critical topic in the scientific community due to the high concentrations encountered in organisms. In this study we attempted to provide information on total Hg accumulation patterns and possible pathways of trophic transfers assessed in combination with δ 13 C and δ 15 N to understand how this contaminant permeates three sub-Antarctic food webs: the Beagle Channel (BC), the Atlantic coast of Tierra del Fuego (AC-TDF) and Burdwood Bank (BB). We found a site-specific pattern of Hg transfer and biomagnification processes, while the oceanic BB showed major Hg transfer through the pelagic domain, coastal sectors (BC and AC-TDF) indicate a general biodilution process but with Hg concentrations incrementing with the benthivory grade. This represents a dissimilar Hg bioavailability for marine consumers that rely on different diet and forage in different habitats, and may become an issue of important conservation concern for these southern areas., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Mercury (Hg) concentrations and stable isotope values (δ 13 C and δ 15 N) were investigated in micronekton collected from La Pérouse and MAD-Ridge seamounts, Reunion Island and the southern Mozambique Channel. Organisms occupying epipelagic habitats showed lower Hg concentrations relative to deeper dwelling benthopelagic ones. Increasing Hg concentrations with increasing body size were recorded in the Mozambique Channel and Reunion Island. Positive relationships were observed between Hg levels and δ 15 N values in pelagic nekton assemblages collected at MAD-Ridge seamount and the southern Mozambique Channel, suggesting biomagnification of Hg. Concentrations of Hg in organisms across the south-western Indian Ocean were within the same range of values. Total Hg concentrations depend on a range of factors linked to habitat range, body size and trophic position of the individuals. To our knowledge, this is the first study investigating the patterns of Hg concentrations in pelagic nekton assemblages from the south-western Indian Ocean., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

We use a multi-tracer approach to identify catchment sources of nitrogen (N) in the skeletons of nearshore Porites corals within the Great Barrier Reef. We measured δ 15 N, δ 13 C and C:N ratios of particulate organic matter (POM) sampled from the Pioneer River catchment and identified five distinct end-members: (1) marine planktonic and algal-dominated matter with higher δ 15 N values from the river mouth and coastal waters; (2) estuarine planktonic and algal matter with lower δ 15 N values associated with estuarine mixing; (3) lower river freshwater phytoplankton and algal-dominated matter in stratified reservoirs adjacent to catchment weirs, with the 15 N-enriched source likely caused by microbial remineralization and denitrification; (4) upper river low δ 15 N terrigenous soil matter eroded from cane fields bordering waterways; and (5) terrestrial plant detrital matter in forest streams, representing a low δ 15 N fixed atmospheric nitrogen source. The δ 15 N values of adjacent, nearshore Porites coral skeletons is reflective of POM composition in coastal waters, with 15 N-enriched values reflective of transformed N during flood pulses from the Pioneer River., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Benthic marine food webs, which recycle organic matter and sustain unique biodiversity, are an important component of estuarine Patagonian fjords; however, these may be heavily influenced by salmon farming activities. Under the above conditions, this study collected several food sources (sediment organic matter, suspended particulate organic matter, macroalgae) and 26 benthic invertebrate species, and analyzed them using a Bayesian mixing model. Briefly, carbon and nitrogen stable isotopes analyses revealed that the highly variable isotopic niche widths respond to food supplies from marine and terrestrial organic matter. In addition, particulate and dissolved waste from salmon farming activities were found to modify isotopic composition ratios in many suspension feeders. Particularly, our results indicate high δ 15 N values in the sponge Cliona chilensis and the encrusting coral Incrustatus comauensis, which appear to be potential ecological indicators for evaluating stoichiometry imbalances and trace organic pollution sources in fjord environments., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The δ 13 C, δ 15 N and C/N ratio of the particulate organic matter (POM) in western Guangdong waters were determined to evaluate the impacts of the coastal currents on the POM in spring and summer. The predominance of photosynthetic organic matter in the nearshore was triggered by nutrients brought by the coastal currents in spring and summer, while the proportion of terrestrial organic matter in the offshore was very high in spring but low in summer. In spring, the weaker and narrower coastal currents carried insufficient nutrients (phosphate deficiency) to the offshore and prohibited phytoplankton production. This scenario contributes to the dominance of terrestrial organic matter transported by the cyclonic circulation beyond the coastal currents in the offshore in spring. The Bayesian mixing model reveals that the proportion of terrestrial organic matter (with 75.8% of C 3 plants) in the offshore was higher in spring than in summer (with 33.7% of C 3 plants)., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

We sampled mussels (Mytilus edulis) along the coast of the Korean peninsula, and determined their trophic position (TP) using the nitrogen isotope ratio of amino acids (TP glu/phe ). The TP glu/phe of mussels (2.0 to 2.5) is higher than TP of herbivores, suggesting that TP normalization is required to remove the trophic enrichment effect on basal nitrogen isotope ratio. We found similar trends in spatial variation between nitrogen isotopic baseline based on nitrogen isotope ratio of bulk tissue (δ 15 N base-bulk ) and that of phenylalanine (δ 15 N base-phe ) in mussels, reflecting different nitrogen sources among sampling sites. The present study suggests that δ 15 N base-bulk and δ 15 N base-phe are powerful tools to trace nitrogen isotopic baselines from primary consumers as well as higher TP organisms., (Copyright © 2021. Published by Elsevier Ltd.)

Mercury (Hg) concentrations based on dietary sources have shown to predict differences in fish; however, they are usually applied at an individual scale and are rarely directed at a known trophic transfer. We combined gut content analysis and stable isotope analysis (δ 15 N and δ 13 C) to provide a quantitative estimate of Hg and selenium (Se) biomagnification in the striped marlin (Kajikia audax) and blue marlin (Makaira nigricans) food web from the southwestern Gulf of California. Hg and Se concentrations (mean ± SD; μg g -1 , dw) were different among K. audax (Hg = 3.6 ± 2.1, Se = 5.5 ± 5.4) and M. nigricans (Hg = 19.0 ± 29.6, Se = 8.8 ± 10.5). Such variations of element concentrations could be linked to predation with different Hg and Se contents. Diet data presented as prey weight (%W) indicated a higher proportion of large prey fish for the blue marlin than the striped marlin. δ 15 N and δ 13 C indicated pelagic food sources with epipelagic preferences for the blue marlin and mesopelagic for the striped marlin. The relationship between Hg concentrations and δ 15 N was positive along the food web of both marlin species, indicating biomagnification of Hg. However, Se biomagnification was not clearly evidenced, and Se:Hg ratios decreased with δ 15 N, attributed to increasing Hg concentrations with increased trophic level., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Mangroves are among the most productive coastal ecosystems; however, they are prone to anthropogenic pollution due to their land-sea interface position. We used stable nitrogen isotopes and spectrophotometric nitrate analysis to study the anthropogenic pollution in five mangrove ecosystems in Tanzania, including two polluted (Mzinga and Kizinga), one moderate (Kunduchi) and non-polluted (Mbegani and Ras Dege) sites. Also, we tested the suitability of mangrove leaves, roots, sediment, and gastropod as indicators of anthropogenic nitrogen pollution using stable δ 15 N isotope analysis. Results revealed higher than 10‰ δ 15 N values in all analysed components and the highest nitrate concentrations of 16.44 mg L -1 in the interstitial waters at the polluted sites, indicating anthropogenic nitrogen inputs. The δ 15 N enrichment increased in the order: non-polluted < moderate < polluted. The polluted sites are fed by freshwater creeks and probably receive high loads of domestic sewage from the surrounding communities, industries, and agricultural effluents. Therefore, to protect mangrove ecosystems, proper waste and wastewater management upstream are recommended., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The isotopic compositions (δ 13 C and δ 15 N) and C/N ratios of suspended particulate organic matter (POM) were investigated off the east coast of Hainan Island in the South China Sea during summer. Coastal upwelling influenced the nearshore stations of transects S2 and S3, and higher δ 13 C and δ 15 N values suggested that coastal upwelling played a significant role in determining the POM sources. The POM at the nearshore area of transect S1 was controlled by the coastal current and freshwater discharge. Additionally, organic matter may be transported to the offshore area via tidal movements in transects S1 and S3. Based on the stable isotope analysis in an R model, the marine organic matter contribution in the upwelling area (19%) was higher than that in the other areas (transect S1 and the offshore area) (7%). The δ 13 C and δ 15 N values and C/N ratios reflect the carbon and nitrogen sources and their cycling in the upwelling zone off the east coast of Hainan Island., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Stable isotopes (δ 13 C and δ 15 N) in marine ecosystem are useful proxies for environmental record. In this study, a time-series analysis of δ 13 C and δ 15 N in two black coral samples collected from off-shore and near-shore environment was performed to investigate variations in climate and environment changes over the last 110 years. The results showed a decreasing trend of δ 13 C in both samples, implying an increase of fossil fuel consumption in modern age - the Suess effect. Meanwhile, a difference in δ 15 N between the offshore and nearshore black coral samples can be attributed to atmospheric transport of natural terrigenous source input and local anthropogenic activities. This study demonstrates that black coral has advantages as an environmental proxy compared with other traditional ones, and suggests that δ 13 C and δ 15 N in black coral can be used as new proxy indicators for climate changes related to anthropogenic activities., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Spatial and temporal variations in stable isotope values of the coastal communities in the Caspian Sea remain poorly understood. We followed carbon stable isotope ratios (δ 13 C) and nitrogen stable isotope ratios (δ 15 N) of primary (gammarids) and secondary (common carp) consumers at four sites with different organic matter loadings along the southern coastline of the Caspian Sea from May to November 2019. Consumers from the site receiving higher sewage effluent and aquaculture wastes were more enriched in δ 15 N whereas those from the site receiving lower terrestrial-derived organic matter had enriched δ 13 C values. Trophic position of consumers varied among sites as a function of organic matter inputs but was independent of month. The observed temporal and spatial variations in the stable isotope values and C:N ratios of the primary and secondary consumers with regards to organic matter loadings, suggesting a possible effect of anthropogenic disturbance on the Caspian Sea ecosystem function., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nitrate is the major chemical form of N-nutrient to sustain primary production in Changjiang Estuary and adjacent seawaters. We employed δ 15 N-NO 3 - and δ 18 O-NO 3 - to constrain the source, cycling, and sink of nitrate in early spring. Both δ 15 N-NO 3 - and δ 18 O-NO 3 - differentiate significantly among Changjiang Diluted Water (CDW), Yellow Sea Coastal Current (YSCC), and Taiwan Warm Current (TWC). In coastal areas, nitrate distribution and its isotopes are mainly affected by Changjiang inputs. Chemical fertilizers and sewage & manure originated nitrate jointly contribute the most nitrate in CDW. In offshore areas, nitrification contributes 44 ± 21% of the nitrate in YSCC and 17 ± 16% in TWC; assimilation is the dominant process to remove nitrate in TWC (35 ± 16%). Overall, nitrification and assimilation are the key nitrate cycling processes in early spring and co-shape the offshore distribution pattern of nitrate and its dual isotopes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The spatial and seasonal variations in resource use of the lacustrine shrimp Palaemon paucidens were investigated in three different Korean lagoon systems in June and October 2018 by measuring their carbon and nitrogen stable isotope ratios. P. paucidens had much higher δ 13 C values at the permanently open lagoon (PL) as compared to the intermittently open lagoons (ILs), revealing a disparity in resource utilization. Isotopic niches of the shrimp were relatively wider at the PL than at the ILs, suggesting a greater diversity of carbon pathways in the PL system. These results indicate that the degree of water exchange with the sea, associated with lagoon geomorphology, may be a major factor influencing resource availability for P. paucidens. Our findings suggest that the duration and degree of inlet opening may affect dietary variation at the population level, and may be one of the key components of sustainable management for coastal lagoon ecosystems., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Sedimentary nitrogen (SN) provenience and fate in surface and subsurface sediments collected from the Baltic Sea were assessed. SN and sedimentary organic carbon (SOC) concentrations, stable isotopic signatures (δ 15 N SN and δ 13 C SOC ) and SOC/SN molar ratios, were determined in subsequent layers of twenty-four sediment cores dated with 210 Pb/ 137 Cs and fifty-seven surface sediments. Sedimentation rates in the range 66-736 g/m 2 yr -1 (0.05-0.34 cm/year) were measured. Prolonged incubation of sediments in the laboratory led to a 17-37% decrease of SN in surface sediments, and no SN loss in sediments deposited before 1940. Decrease of δ 15 N SN on incubation (1‰ on average), and gradients of δ 15 N SN , between recent - surface (3.5‰) vs. 100 years old - subsurface (2.1‰) sediments were attributed to varying contributions of labile nitrogen to the SN pool. Annual deposition of SN to sediment surface and burial in subsurface sediments amounted, respectively, to 5 ± 2 g/m 2 and 3.5 ± 1 g/m 2 ., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Stable isotopic composition of carbon (δ 13 C POM ) and nitrogen (δ 15 N POM ) in the particulate organic matter (POM) is used to identify sources of organic carbon and nutrients using monthly time-series observation in the coastal Bay of Bengal (BoB). The hydrographic structure indicates that the coastal BoB is influenced by coastal upwelling during March-May, advection of peninsular river discharge during June to September and glacial (Ganges) river discharge during October to December due to reversing of East India Coastal Currents (EICC). C/N ratios in POM were mostly higher values than Redfield ratio in the study region indicating possible contribution of terrestrial origin. Enriched δ 13 C POM were found during March-May associated with coastal upwelling indicating major contribution of POM from the in situ production while lower values were noticed during June to September followed by October to December indicating influence of terrestrial sources. δ 15 N POM displayed strong inverse relation with salinity and linear relation with Chl-a suggesting that anthropogenic nutrients from the land increased coastal phytoplankton biomass. δ 15 N POM linearly decreased with increase in distance from the coast and reached to the typical offshore value of 6-6.5‰ indicating that terrestrial nutrients influence was spread up to a distance of 15 to 20 km from the coast in the study region. Our study suggested that coastal waters are influenced by terrestrial/anthropogenic nutrients and its impact can be noticed up to 15 to 20 km from the coast and its impact on Biodiversity Beyond National Jurisdiction may be negligible than hitherto hypothesized., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

It remains challenging to identify nitrate sources in streams due to complications associated with anthropogenic inputs and in-stream biogeochemical processes. We used dual isotopic analysis of nitrate and a Bayesian isotope mixing model to explore the dynamics of nitrate sources and their associated transformations among three types of headwater watershed with different dominant land use types during four seasons in Jiulong River Watershed, a coastal China watershed. Nitrogen sources were the primary determinant of the δ 15 N-NO 3 and seasonal differences in biogeochemical processes exhibited among watersheds. Nitrate was mostly derived from nitrification in spring and summer, whereas atmospheric deposition greatly influenced the isotopic composition in autumn and winter. Chemical fertilizer contributed the largest to the riverine nitrate, accounting for 36.9 ± 12.3%, followed by soil N (27.2 ± 4.4%), atmospheric deposition (23.9 ± 11.8%) and manure & sewage (12.0 ± 5.9%). This study reveals the seasonality of riverine nitrate sources under changing watershed land use patterns., Competing Interests: Declaration of competing interest No conflict of the interest exits in the submission of this manuscript, and manuscript is approved by all the authors for publication., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Pulau Redang and Pulau Tioman have experienced huge tourism growth over the last two decades, but minimal sewage treatment may threaten the resilience of their coral reefs. This study uses stable isotope techniques to identify suitable bioindicators of sewage nutrients (δ 15 N) at these islands by measuring macroalgae (Lobophora spp.), gastropods (Drupella spp.), scleractinian coral (Acropora spp.), and leather coral (Sinularia spp.). At tourist hubs using seepage septic tank systems, enrichment of Acropora δ 15 N (Redang, +0.7‰) and Sinularia δ 15 N (Tioman, +0.4‰) compared to pristine background levels indicate enhanced sewage nutrient discharge. Carbon isotopes and survey data suggest that sedimentation did not confound these δ 15 N trends. Potential damaging effects of sewage discharge on the coral reef communities at both islands are highlighted by strong correlations between Acropora δ 15 N and regional variation in coral reef community structure, and exclusive occurrence of degraded reefs at regions of high sewage influence., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Organic pollution is a serious environmental problem for the coastal zones of seas. The study tested the hypothesis that allochthonous organic carbon derived from St. Petersburg wastewaters is a significant basal resource of carbon for the benthic food webs. We analyzed stable isotope composition of carbon and nitrogen in suspended organic matter in the Neva Estuary and in the tissues of macroinvertebrates and fish. The Stable Isotope Bayesian mixing model showed that waste waters were an important source of carbon for the most of consumers in the Neva Estuary. The autochthonous carbon produced by phytoplankton was a significant source of carbon only for some macroinvertebrates. The main consumers of the carbon derived from waste waters were tubificid worms, chironomid larvae and alien polychaete, which currently dominate in the zoobenthos of the estuary. These species replaced the former dominants, native crustaceans, which to a lesser extent use anthropogenic carbon., (Copyright © 2019. Published by Elsevier Ltd.)

Sources of organic matter in a polluted coastal embayment (Lake Sihwa) indicated that δ 13 C and δ 15 N of suspended particulate matter (SPM) and sediments could be distinguished by land-use type and surrounding activities. Specifically, low δ 15 N occurred in inland creeks near industrial complex, where severe contamination by persistent toxic substances (PTSs) is evidenced. To identify the sources of 15 N-depleted organic matter and PTSs, the SPM and/or sediments were collected along ~8 km of the Singil Creek and in stormwater drainage pipes that carried pollutants to the creeks from upland areas. Results indicated that stormwater originating in industrial areas was the main source of low δ 15 N and elevated PTSs, which appeared to flow into stormwater drains with rainwater and eventually into the creeks at stormwater outfalls. To improve the water quality of inland creeks, it will be necessary to reduce the amount of untreated stormwater entering stormwater drainage system from industrial complex., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Dual isotope nitrate (NO 3 - ) analysis was performed on the western coast of Guangdong Province to investigate seasonal changes in the main nitrate sources and their biogeochemical processing, which are due to the rapid development of the local economy. In the nearshore area, significant seasonal variations of nitrate sources occurred. The dominant nitrate sources, originating from manure and sewage, suggested that the nitrate along the west coast of Guangdong Province was mainly influenced by local cities despite the westward flow of diluted Pearl River water. In the offshore area, the nitrate loss in the upper and mid water during both two seasons mainly caused by phytoplankton assimilation, whereas coupled nitrification-denitrification could be responsible for the nitrate loss in the bottom waters during summer. Our results suggest that, with the rapid development of local economy, the nitrate sources in the coastal area have shifted to manure and sewage from the local cities., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

To investigate the effects of mariculture on the sources, distribution and preservation of sedimentary organic carbon (SOC), sediments from an mariculture area in Ailian Bay, China, and a control area were analyzed for grain size composition, total organic carbon (TOC), total nitrogen (TN), carbon/nitrogen (C/N) ratio, and stable carbon and nitrogen isotopic composition (δ 13 C and δ 15 N). The sedimentary type of sediments in study area was clay silt. TOC, TN, C/N, δ 13 C, and δ 15 N ranged from 0.58 to 1.21%, 0.06-0.17%, 6.29-9.82, -23.20 to -18.50‰, and 6.17-7.38‰, respectively, and followed similar spatial patterns. TOC, TN and δ 13 C were higher in mariculture area than in control area. Biodeposit and kelp OC contributions greater of SOC in mariculture area than the control area (biodeposits: 20.10 ± 4.84 to 6.2 ± 1.3%; kelp: 15.3 ± 6.63 to 5.2 ± 0.84%). Overall, mariculture activities significantly influence the sources, distribution and preservation of SOC., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

A combined approach merging stable isotopes and fatty acids was applied to study anthropogenic pollution in the Río Negro estuary. Fatty acid markers of vegetal detritus indicated considerable allochthonous inputs at freshwater sites. Correlative evidence of diatom fatty acids, δ 13 C, chlorophyll and particulate organic matter suggested the importance of diatoms for the autochthonous organic matter production at the river mouth. Low δ 15 N values (~0‰) and high fatty acid 18:1(n-7) concentrations in the suspended particulate matter, in combination with the peaks of coliforms and ammonium, indicated a strong impact of untreated sewage discharge. The 15 N depletion was related to oxygen-limited ammonification processes and incorporation of 15 N depleted ammonium to microorganisms. This work demonstrates that the combined use of lipid and isotopic markers can greatly increase our understanding of biogeochemical factors and pollutants influencing estuaries, and our findings highlight the urgent need for water management actions to reduce eutrophication., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Mercury (Hg) biotransformation and biomagnification are processes that affect Hg burdens in wildlife. To interpret variation in Hg in seabird eggs, used as Hg bioindicators in the Arctic, it is important to understand how Hg biomagnifies through the food web. We evaluated the use of δ 34 S, along with other commonly used stable isotope signatures (δ 15 N and δ 13 C), for the determination of possible sources of Hg in an Arctic food web (56 individuals of 15 species of fish and invertebrates). Hg correlated with δ 34 S (R 2  = 0.72). When the combined effects of δ 34 S and δ 15 N were considered in mixed-effects models, both δ 34 S and δ 15 N together described Hg patterns in Arctic food webs better than either isotope alone. Our results demonstrate the usefulness of δ 34 S to account for variation in Hg among marine animals and to study the possible underlying effects that MeHg production may have on Hg pathways in Arctic ecosystems., (Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.)

The present study has evaluated temporal and spatial mercury trends based on surficial sediment samples and 210 Pb-dated sediment profiles. The obtained results show that there are areas close to the main bay's tributary rivers where the Hg content has doubled during the last 15 years and regions where it has decreased by a factor of 2, mainly the area close to the navigation channel, which is submitted to periodic dredging. In the inner part of the bay, the most contaminated region, mercury shows a strong association with sulfide. In the same region, based on the 210 Pb results, it was possible to calculate the yearly increment on the Hg concentration in the surface sediment, 0.62 μg kg -1  y -1 to 0.29 μg kg -1  y -1 , according to the distance to the bay's main tributary rivers., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Nutrient loading from sewage wastewater discharge contributes to the eutrophication of coastal waters. Wastewater from the Gold Coast, Australia is discharged into the Gold Coast Seaway (GCS) for 13.5 h d -1 primarily on the ebbing tide to disperse wastewater seawards. Nitrogen stable isotopes were used to assess how effectively the tidally staged release system dispersed wastewater out of the GCS and identified pathways by which sewage-N was incorporated into food webs. Turf algae, limpets and barnacles were sampled at the GCS, at two coastal sites and at the mouth of a control estuary that lacked point-source discharge. In the GCS δ 15 N values of algae and limpets returned to coastal baseline levels within 250 m of the diffusers. In contrast, δ 15 N of filter-feeding barnacles did not significantly vary indicating wastewater-N does not dominate the pelagic food web. Nitrogen stable isotopes clearly demonstrated that the tidally-staged wastewater release system effectively disperses wastewater offshore., (Copyright © 2018 Elsevier Ltd. All rights reserved.)