Effects of contaminants and trophic cascade regulation on food chain stability: Application to cadmium soil pollution on small mammals – Raptor systems

Ecological impacts and potential hazards of nickel on soil microbes, plants, and human health

Nickel (Ni) contamination poses a serious environmental concern, particularly in developing countries: where, anthropogenic activities significantly contributes to Ni accumulations in soils and waters. The contamination of agricultural soils with Ni, increases risks of its entry to terrestrial ecosystems and food production systems posing a threat to both food security and safety. We examined the existing published articles regarding the origin, source, accumulation, and transport of Ni in soil environments. Particularly, we reviewed the bioavailability and toxic effects of Ni to soil invertebrates and microbes, as well as its impact on soil-plant interactions including seed germination, nutrient uptake, photosynthesis, oxidative stress, antioxidant enzyme activity, and biomass production. Moreover, it underscores the potential health hazards associated with consuming crops cultivated in Ni-contaminated soils and elucidates the pathways through which Ni enters the food chain. The published literature suggests that chronic Ni exposure may have long-term implications for the food supply chain and the health of the public. Therefore, an aggressive effort is required for interdisciplinary collaboration for assessing and mitigating the ecological and health risks associated with Ni contamination. It also argues that these measures are necessary in light of the increasing level of Ni pollution in soil ecosystems and the potential impacts on public health and the environment.

Lead poisoning of raptors: state of the science and cross-discipline mitigation options for a global problem

Lead poisoning is an important global conservation problem for many species of wildlife, especially raptors. Despite the increasing number of individual studies and regional reviews of lead poisoning of raptors, it has been over a decade since this information has been compiled into a comprehensive global review. Here, we summarize the state of knowledge of lead poisoning of raptors, we review developments in manufacturing of non-lead ammunition, the use of which can reduce the most pervasive source of lead these birds encounter, and we compile data on voluntary and regulatory mitigation options and their associated sociological context. We support our literature review with case studies of mitigation actions, largely provided by the conservation practitioners who study or manage these efforts. Our review illustrates the growing awareness and understanding of lead exposure of raptors, and it shows that the science underpinning this understanding has expanded considerably in recent years. We also show that the political and social appetite for managing lead ammunition appears to vary substantially across administrative regions, countries, and continents. Improved understanding of the drivers of this variation could support more effective mitigation of lead exposure of wildlife. This review also shows that mitigation strategies are likely to be most effective when they are outcome driven, consider behavioural theory, local cultures, and environmental conditions, effectively monitor participation, compliance, and levels of raptor exposure, and support both environmental and human health.

Advancing exposure assessment approaches to improve wildlife risk assessment

The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering "all relevant factors." This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment-chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an "exposure matrix." Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking. Integr Environ Assess Manag 2024;20:674-698. © 2023 SETAC.

Application of Chlorophyll Fluorescence Analysis Technique in Studying the Response of Lettuce (Lactuca sativa L.) to Cadmium Stress

To reveal the impact of cadmium stress on the physiological mechanism of lettuce, simultaneous determination and correlation analyses of chlorophyll content and photosynthetic function were conducted using lettuce seedlings as the research subject. The changes in relative chlorophyll content, rapid chlorophyll fluorescence induction kinetics curve, and related chlorophyll fluorescence parameters of lettuce seedling leaves under cadmium stress were detected and analyzed. Furthermore, a model for estimating relative chlorophyll content was established. The results showed that cadmium stress at 1 mg/kg and 5 mg/kg had a promoting effect on the relative chlorophyll content, while cadmium stress at 10 mg/kg and 20 mg/kg had an inhibitory effect on the relative chlorophyll content. Moreover, with the extension of time, the inhibitory effect became more pronounced. Cadmium stress affects both the donor and acceptor sides of photosystem II in lettuce seedling leaves, damaging the electron transfer chain and reducing energy transfer in the photosynthetic system. It also inhibits water photolysis and decreases electron transfer efficiency, leading to a decline in photosynthesis. However, lettuce seedling leaves can mitigate photosystem II damage caused by cadmium stress through increased thermal dissipation. The model established based on the energy captured by a reaction center for electron transfer can effectively estimate the relative chlorophyll content of leaves. This study demonstrates that chlorophyll fluorescence techniques have great potential in elucidating the physiological mechanism of cadmium stress in lettuce, as well as in achieving synchronized determination and correlation analyses of chlorophyll content and photosynthetic function.

Relationships among protozoa, bacteria and fungi in polycyclic aromatic hydrocarbon-contaminated soils

Soil bacterial and fungal communities play key roles in the degradation of organic contaminants, and their structure and function are regulated by bottom-up and top-down factors. Microbial ecological effects of polycyclic aromatic hydrocarbons (PAHs) and trophic interactions among protozoa and bacteria/fungi in PAH-polluted soils have yet to be determined. We investigated the trophic interactions and structure of the microbiome in PAH-contaminated wasteland and farmland soils. The results indicated that the total concentration of the 16 PAHs (∑PAHs) was significantly correlated with the Shannon index, NMDS1 and the relative abundances of bacteria, fungi and protozoa (e.g., Pseudofungi) in the microbiome. Structural equation modelling and linear fitting demonstrated cascading relationships among PAHs, protozoan and bacterial/fungal communities in terms of abundance and diversity. Notably, individual PAHs were significantly correlated with microbe-grazing protozoa at the genus level, and the abundances of these organisms were significantly correlated with those of PAH-degrading bacteria and fungi. Bipartite networks and linear fitting indicated that protozoa indirectly modulate PAH degradation by regulating PAH-degrading bacterial and fungal communities. Therefore, protozoa might be involved in regulating the microbial degradation of PAHs by predation in contaminated soil.

Ecological risk of phenol on typical biota of the northern Chinese river from an integrated probability perspective: the Hun River as an example

Phenol, known for its bioaccumulative nature and severe toxicity to riverine organisms, poses complex challenges for ecological risk assessment. To tackle this issue, we developed a three-stage incremental assessment method, providing an integrated perspective on phenol toxicity risk for aquatic organisms. The findings indicated that phenol concentrations were generally higher in the aquatic environments of northern rivers, such as the Hun River, Taizi River, and Liao River, compared to those in southern China. The evaluation results at individual points showed that the ecological risk of phenol to aquatic organisms ranked from high to low during rainy, dry, and normal seasons, showing seasonal variation characteristics. Regarding spatial variation along the river, the ecological risk of phenol gradually increased from upper reaches, peaked in the middle reaches, and then decreased in the lower reaches. Considering the different species types, fish face a higher risk of toxic effects of phenol than invertebrates when exposed to phenol over a long period of time, probably due to the bioaccumulative nature of phenol. To address ecological risk control at the watershed scale, there is an urgent need to revise China's current river water quality standards. It is essential to increase the emphasis on ecological risk control for aquatic organisms. Developing more targeted and refined ecological risk control strategies for river phenols is crucial to maintain a healthier and more vibrant river ecosystem.

Long-term monitoring of exposure to toxic and essential metals and metalloids in the tawny owl (Strix aluco): Temporal trends and influence of spatial patterns

As a result of regulatory decisions, atmospheric deposition of most toxic metals and metalloids (MEs) has decreased in Europe over the past few decades. However, little is known about how this reduction translates into exposure at higher trophic levels in the terrestrial environment where temporal trends may be spatially heterogeneous due to local current or legacy sources of emissions (e.g., industry) or long-range transport of elements (e.g., marine transport). The aim of this study was to characterize temporal and spatial trends of exposure to MEs in terrestrial food webs using a predatory bird, the tawny owl Strix aluco, as a biomonitor. Toxic (Al, As, Cd, Hg, Pb) and essential/beneficial (B, Co, Cu, Mn, Se) elemental concentrations were measured in feathers of nest-captured females from 1986 to 2016, extending a previous study published over the time-series 1986-2005 (n = 1051), in a breeding population in Norway. A drastic decline over time was shown for the toxic MEs (-97 % for Pb, -89 % for Cd, -48 % for Al, and -43 % for As) except Hg. The beneficial elements B, Mn, and Se showed oscillations but an overall decline (-86 %, -34 %, and -12 %, respectively) whereas the essentials Co and Cu did not exhibit significant trends. The distance to potential sources of contamination influenced both the spatial patterns of concentrations in owl feathers and their temporal trends. The accumulation of As, Cd, Co, Mn and Pb was overall higher in the vicinity of sites recorded as polluted, and a greater temporal decrease of As, B, and Cd concentrations was found in the areas of further distance to polluted sites. The decrease of Pb concentrations was sharper further from the coast during the 1980s than in coastal areas, while the opposite was observed for Mn. The levels of Hg and Se were higher in coastal areas, and Hg temporal trends differed according to the distance to the coast. This study highlights the valuable insights provided by long-term survey of wildlife exposure to pollutants and landscape indicators to reveal regional or local patterns and detect unexpected events, data that are crucial for regulation and conservation of ecosystem health.

Pervasive exposure of wild small mammals to legacy and currently used pesticide mixtures in arable landscapes

Knowledge gaps regarding the potential role of pesticides in the loss of agricultural biodiversity worldwide and mixture-related issues hamper proper risk assessment of unintentional impacts of pesticides, rendering essential the monitoring of wildlife exposure to these compounds. Free-ranging mammal exposure to legacy (Banned and Restricted: BRPs) and currently used (CUPs) pesticides was investigated, testing the hypotheses of: (1) a background bioaccumulation for BRPs whereas a "hot-spot" pattern for CUPs, (2) different contamination profiles between carnivores and granivores/omnivores, and (3) the role of non-treated areas as refuges towards exposure to CUPs. Apodemus mice (omnivore) and Crocidura shrews (insectivore) were sampled over two French agricultural landscapes (n = 93). The concentrations of 140 parent chemicals and metabolites were screened in hair samples. A total of 112 compounds were detected, showing small mammal exposure to fungicides, herbicides and insecticides with 32 to 65 residues detected per individual (13-26 BRPs and 18-41 CUPs). Detection frequencies exceeded 75% of individuals for 13 BRPs and 25 CUPs. Concentrations above 10 ng/g were quantified for 7 BRPs and 29 CUPs (in 46% and 72% of individuals, respectively), and above 100 ng/g for 10 CUPs (in 22% of individuals). Contamination (number of compounds or concentrations) was overall higher in shrews than rodents and higher in animals captured in hedgerows and cereal crops than in grasslands, but did not differ significantly between conventional and organic farming. A general, ubiquitous contamination by legacy and current pesticides was shown, raising issues about exposure pathways and impacts on ecosystems. We propose a concept referred to as "biowidening", depicting an increase of compound diversity at higher trophic levels. This work suggests that wildlife exposure to pesticide mixtures is a rule rather than an exception, highlighting the need for consideration of the exposome concept and questioning appropriateness of current risk assessment and mitigation processes.

In situ and ex situ bioassays with Cantareus aspersus for environmental risk assessment of metal(loid) and PAH-contaminated soils

Environmental risk assessment of contaminated soils requires bioindicators that allow the assessment of bioavailability and toxicity of chemicals. Although many bioassays can determine the ecotoxicity of soil samples in the laboratory, few are available and standardized for on-site application. Bioassays based on specific threshold values that assess the in situ and ex situ bioavailability and risk of metal(loid)s and polycyclic aromatic hydrocarbons (PAHs) in soils to the land snail Cantareus aspersus have never been simultaneously applied to the same soils. The aims of this study were to compare the results provided by in situ and ex situ bioassays and to determine their respective importance for environmental risk assessment. The feasibility and reproducibility of the in situ bioassay were assessed using an international ring test. This study used five plots located at a former industrial site and six laboratories participated in the ring test. The results revealed the impact of environmental parameters on the bioavailability of metal(loid)s and PAHs to snails exposed in the field to structured soils and vegetation compared to those exposed under laboratory conditions to soil collected from the same field site (excavated soils). The risk coefficients were generally higher ex situ than in situ, with some exceptions (mainly due to Cd and Mo), which might be explained by the in situ contribution of plants and humus layer as sources of exposure of snails to contaminants and by climatic parameters. The ring test showed good agreement among laboratories, which determined the same levels of risk in most of the plots. Comparison of the bioavailability to land snails and the subsequent risk estimated in situ or ex situ highlighted the complementarity between both approaches in the environmental risk assessment of contaminated soils, namely, to guide decisions on the fate and future use of the sites (e.g., excavation, embankments, and land restoration). Integr Environ Assess Manag 2022;18:539-554. © 2021 SETAC.

Distribution characteristics, bioaccumulation and trophic transfer of heavy metals in the food web of grassland ecosystems

In this study, according to the classification of biological "classes" and the different trophic levels of the food web, the distribution characteristics, bioaccumulation of heavy metals (HMs) and their trophic transfer in the food web of typical grassland ecosystems were studied and predicted. The results indicated that the accumulation of toxic As was the highest in small mammals and reptiles, Cu was the highest in insects, and the micronutrient Zn in large mammals was higher than that in plants. The metal transfer factor (MTF) by plants at the first trophic level showed that Leymus chinensis had the best ability to absorb HMs from soil. The trophic transfer factor (TTF) of HMs in the second-trophic level insects, birds and some mammals were Zn > As > Cu > Ni > Pb > Co = Cr > Mn > V, in which, biomagnified on Zn, As, and Cu. Organisms at the third trophic level including birds, reptiles and some mammals had the strongest accumulation ability for Pb, V and As, and all were biomagnified. The biomagnification on As and Co of the fourth trophic level Siberian weasel was obviously higher than that of Dione's rat-snake, which had significant biomagnification effect on As by preying on Steppe toad-headed agama. The study showed that the bioaccumulation levels of HMs in organisms at different trophic levels varied significantly with species, prey, and organ type, but they all showed strong bioaccumulation capacity to toxic As, which indicated that As could produce certain toxic effects on animals in the food web through trophic transfer. In addition, organisms at low-trophic levels were more likely to biomagnify Zn, while organisms at high-trophic levels were more likely to biodilute Pb.

Stoichiometric Ecotoxicology for a Multisubstance World

Nutritional and contaminant stressors influence organismal physiology, trophic interactions, community structure, and ecosystem-level processes; however, the interactions between toxicity and elemental imbalance in food resources have been examined in only a few ecotoxicity studies. Integrating well-developed ecological theories that cross all levels of biological organization can enhance our understanding of ecotoxicology. In the present article, we underline the opportunity to couple concepts and approaches used in the theory of ecological stoichiometry (ES) to ask ecotoxicological questions and introduce stoichiometric ecotoxicology, a subfield in ecology that examines how contaminant stress, nutrient supply, and elemental constraints interact throughout all levels of biological organization. This conceptual framework unifying ecotoxicology with ES offers potential for both empirical and theoretical studies to deepen our mechanistic understanding of the adverse outcomes of chemicals across ecological scales and improve the predictive powers of ecotoxicology.

When the average hides the risk of Bt-corn pollen on non-target Lepidoptera: Application to Aglais io in Catalonia

Field cultivation of Genetically Modified (GM) Bt-plants has a potential environmental risk toward non-target Lepidoptera (NTLs) larvae through the consumption of Bt-maize pollen. The Bt-maize Cry protein targeting Lepidoptera species detrimental to the crop is also expressed in pollen which is dispersed by wind and can thus reach habitats of NTLs. To better assess the current ecological risk of Bt-maize at landscape scales, we developed a spatially-explicit exposure-hazard model considering (i) the dynamics of pollen dispersal obtained by convolving GM plants emission with a dispersal kernel and (ii) a toxicokinetic-toxicodynamic (TKTD) model accounting for the impact of toxin ingestion on individual lethal effects. We simulated the model using real landscape observations in Catalonia (Spain): GM-maize locations, flowering dates, rainfall time series and larvae emergence date of the European peacock butterfly Aglais io. While in average, the additional mortality appears to be negligible, we show significant additional mortality at sub-population level, with for instance a mortality higher than 40% within the 10m for the 10% most Bt-sensitive individuals. Also, using Pareto optimality we capture the best trade-off between isolation distance and additional mortality: up to 50 m are required to significantly buffer Bt-pollen impact on NTLs survival at the individual level. Our study clears up the narrow line between diverging conclusions: those claiming no risk by only looking at the average regional effect of Bt on NTLs survival and those pointing out a significant threaten when considering the variability of individuals mortality.

Potential human health hazard due to bioavailable heavy metal exposure via consumption of plants with ethnobotanical usage at the largest chromite mine of India

Usage of native plant species for traditional medicine or nutritional supplement is a popular practice among various cultures. But consumption of plants growing on polluted soil can cause serious human health hazard due to bioaccumulation of toxic heavy metals. Present study deals with the ecological and human health impact of heavy metals, in six native plant species with ethnobotanical significance growing at the largest chromite mine of India. Exchangeable, oxidizable, reducible and residual fractions of the metals in plant rhizosphere were analyzed. Only 2-6% of total Cr (270-330 mg/kg) and Ni (150-190 mg/kg) at the mining site is bioavailable. Cd showed highest bioavailability (~ 60%) in mining site posing very high ecological risk (1055-5291) followed by Ni (1297-2124) and Cr (309-1105). The heavy metals in the shoot of the targeted plants were about 0.7 to 80 times higher than the standard limit as per Indian statutory body. The total hazard quotient (THQ) by the consumption of plants growing in mining region was very high (> 1) and varied from 2.6 to 5.9 in adult and 0.6-1.3 in children, while in non-mining region the THQ of same plants indicates low risk (< 1). This study indicates THQ (adult) in the order of, Euphorbia hirta (5.9) > Calotropis procera (4.9) > Argemone mexicana (3.6) > Vernonia cinerea (3.5) > Pteridium latiusculum (3.4) > Tridax procumbens (2.6) through consumption pathway growing in mine soil. This study concludes that consumption of plants growing in heavy metal polluted soil should be avoided due to their potential health hazard.

Identification and functional characterization of ABCC transporters for Cd tolerance and accumulation in Sedum alfredii Hance

Cd is one of the potential toxic elements (PTEs) exerting great threats on the environment and living organisms and arising extensive attentions worldwide. Sedum alfredii Hance, a Cd hyperaccumulator, is of great importance in studying the mechanisms of Cd hyperaccumulation and has potentials for phytoremediation. ATP-binding cassette sub-family C (ABCC) belongs to the ABC transporter family, which is deemed to closely associate with multiple physiological processes including cellular homeostasis, metal detoxification, and transport of metabolites. In the present work, ten ABCC proteins were identified in S. alfredii Hance, exhibiting uniform domain structure and divergently clustering with those from Arabidopsis. Tissue-specific expression analysis indicated that some SaABCC genes had significantly higher expression in roots (Sa23221 and Sa88F144), stems (Sa13F200 and Sa14F98) and leaves (Sa13F200). Co-expression network analysis using these five SaABCC genes as hub genes produced two clades harboring different edge genes. Transcriptional expression profiles responsive to Cd illustrated a dramatic elevation of Sa14F190 and Sa18F186 genes. Heterologous expression in a Cd-sensitive yeast cell line, we confirmed the functions of Sa14F190 gene encoding ABCC in Cd accumulation. Our study performed a comprehensive analysis of ABCCs in S. alfredii Hance, firstly mapped their tissue-specific expression patterns responsive to Cd stress, and characterized the roles of Sa14F190 genes in Cd accumulation.

Temperature and Estrogen Alter Predator-Prey Interactions between Fish Species

A variety of environmental estrogens are commonly detected in human-impacted waterways. Although much is known about the effects of these environmental estrogens on the reproductive physiology and behavior of individuals within species, comparatively less is known about how these compounds alter the outcomes of interactions between species. Furthermore, few studies have considered how the effects of contaminants are modulated by natural variation in abiotic factors, such as temperature. To help fill this knowledge gap, we conducted a factorial experiment to examine the independent and combined effects of estrone (E1) and temperature on the outcome of predator-prey interactions between two common North American freshwater fishes, fathead minnows (Pimephales promelas) and bluegill sunfish (Lepomis macrochirus). Larval fathead minnows and adult sunfish were exposed to either a low (mean±standard deviation, 90.1 ± 18 ng/L; n = 16) or high (414 ± 147 ng/L; n = 15) concentration of E1 or to a solvent control for 30 days at one of four natural seasonal temperatures (15°C, 18°C, 21°C, and 24°C) before predation trials were performed. Exposure to E1 was associated with a significant increase in larval predation mortality that was independent of temperature. Across all temperature treatments, approximately 74% of control minnows survived; this survivorship significantly exceeded that of minnows exposed to either concentration of E1 (49% and 53% for minnows exposed to the low and high concentrations, respectively). However, exposure to E1 also impaired the prey-capture success of sunfish, partially mitigating predation pressure on exposed minnows. Overall prey-capture success by sunfish showed an inverted U-shaped distribution with temperature, with maximal prey consumption occurring at 21°C. This study illustrates the vulnerability of organismal interactions to estrogenic pollutants and highlights the need to include food web interactions in assessments of risk.

Recommendations to address uncertainties in environmental risk assessment using toxicokinetic-toxicodynamic models

Providing reliable environmental quality standards (EQSs) is a challenging issue in environmental risk assessment (ERA). These EQSs are derived from toxicity endpoints estimated from dose-response models to identify and characterize the environmental hazard of chemical compounds released by human activities. These toxicity endpoints include the classical x% effect/lethal concentrations at a specific time t (EC/LC(x, t)) and the new multiplication factors applied to environmental exposure profiles leading to x% effect reduction at a specific time t (MF(x, t), or denoted LP(x, t) by the EFSA). However, classical dose-response models used to estimate toxicity endpoints have some weaknesses, such as their dependency on observation time points, which are likely to differ between species (e.g., experiment duration). Furthermore, real-world exposure profiles are rarely constant over time, which makes the use of classical dose-response models difficult and may prevent the derivation of MF(x, t). When dealing with survival or immobility toxicity test data, these issues can be overcome with the use of the general unified threshold model of survival (GUTS), a toxicokinetic-toxicodynamic (TKTD) model that provides an explicit framework to analyse both time- and concentration-dependent data sets as well as obtain a mechanistic derivation of EC/LC(x, t) and MF(x, t) regardless of x and at any time t of interest. In ERA, the assessment of a risk is inherently built upon probability distributions, such that the next critical step is to characterize the uncertainties of toxicity endpoints and, consequently, those of EQSs. With this perspective, we investigated the use of a Bayesian framework to obtain the uncertainties from the calibration process and to propagate them to model predictions, including LC(x, t) and MF(x, t) derivations. We also explored the mathematical properties of LC(x, t) and MF(x, t) as well as the impact of different experimental designs to provide some recommendations for a robust derivation of toxicity endpoints leading to reliable EQSs: avoid computing LC(x, t) and MF(x, t) for extreme x values (0 or 100%), where uncertainty is maximal; compute MF(x, t) after a long period of time to take depuration time into account and test survival under pulses with different periods of time between them.

Heavy Metals in Biota in Delaware Bay, NJ: Developing a Food Web Approach to Contaminants

Understanding the relationship between heavy metal and selenium levels in biota and their foods is important, but often difficult to determine because animals eat a variety of organisms. Yet such information is critical to managing species populations, ecological integrity, and risk to receptors (including humans) from consumption of certain prey. We examine levels of cadmium, lead, mercury, and selenium in biota from Delaware Bay (New Jersey, USA) to begin construction of a “springtime” food web that focuses on shorebirds. Horseshoe crab (Limulus polyphemus) eggs are one of the key components at the base of the food web, and crab spawning in spring provides a food resource supporting a massive stopover of shorebirds. Fish and other biota also forage on the crab eggs, and a complex food web leads directly to top-level predators such as bluefish (Pomatomus saltatrix) and striped bass (Morone saxatilis), both of which are consumed by egrets, eagles, ospreys (Pandion haliaetus), and humans. Metal levels in tissues were generally similar in algae, invertebrates, and small fish, and these were similar to those in blood of shorebirds (but not feathers). There was a significant direct relationship between the levels of metals in eggs of horseshoe crabs and mean metal levels in the blood of four species of shorebirds. Metal levels in shorebird feathers were higher than those in blood (except for selenium), reflecting sequestration of metals in feathers during their formation. Levels in feathers of laughing gulls (Leucophaeus atricilla) were similar to those in feathers of shorebirds (except for selenium). Selenium bears special mention as levels were significantly higher in the blood of all shorebird species than in other species in the food web, and were similar to levels in their feathers. Levels of metals in bluefish and striped bass were similar or higher than those found in the blood of shorebirds (except for selenium). The mean levels of cadmium, lead, and mercury in the blood and feathers of shorebirds were below any effect levels, but selenium levels in the blood and feathers of shorebirds were higher than the sublethal effect levels for birds. This is a cause for concern, and warrants further examination.