Mercury Biomagnification Research Articles

A Meta-Analysis of Mercury Biomagnification in Freshwater Predatory Invertebrates: Community Diversity and Dietary Exposure Drive Variability.

Accurate estimates of methylmercury (MeHg) exposure are valuable to actionably assess risk and protect wildlife and human health. MeHg trophic transfer is a critical driver of risk: MeHg is generally biomagnified by a factor of 8.3 ± 7.5 from one trophic level to the next, averaged across freshwater communities (mean ± standard deviation). This variability can produce disparate risks even where basal MeHg concentrations are similar. Taxonomy may be one driver of this variability: physiologically diverse groups, like vertebrates and invertebrates, may assimilate MeHg differently. To determine whether taxonomy affects trophic transfer efficiency, we conducted a meta-analysis characterizing predatory invertebrate MeHg biomagnification. Our analyses estimated that freshwater predatory invertebrates biomagnify MeHg by factors of 2.1 ± 0.2 to 4.3 ± 0.3, with a 98.9 ± 0.4% posterior probability that factors are below 5 (mean ± standard error). When vertebrates or primary producers were included, a site's trophic magnification factor was 18.6 ± 6.2 to 54.1 ± 7.7% higher than estimates for invertebrates alone. Biomagnification was inversely correlated to prey MeHg concentration and varied among systematic and functional groups. These data suggest that predatory invertebrates biomagnify MeHg less efficiently than vertebrates and that a community's diversity and structure determine its biomagnification efficiency. Incorporating organismal variation in trophic transfer estimates may improve the assessment, communication, and management of MeHg risk.

Mercury biomagnification in the food chain of a piscivorous turtle species (Testudines: Chelidae: Chelus fimbriata) in the Central Amazon, Brazil.

Due to their natural history and ecological attributes, turtles are excellent organisms for studies of heavy metal contamination. Turtles have a large geographical distribution, occupy different aquatic habitats, and occupy various trophic levels. The present study investigated mercury bioaccumulation in the carnivorous chelonian Chelus fimbriata (Matamata turtle) and Hg biomagnification in relation to its aquatic food chain in the middle Rio Negro, AM-Brazil. Tissue samples of muscle, carapace and claws were collected from 26 C. fimbriata individuals, as well as collections of autotrophic energy sources found in the turtle's aquatic habitat area. The samples were collected in February-March/2014 and analyzed for THg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotopes. The highest THg levels were found in claws (3780 ng.g-1), carapace (3622 ng.g-1) and muscle (403 ng.g-1), which were found to be significantly different [F(2.73) = 49.02 p < 0.01]. However, THg concentrations in muscle tissue were below the consumption threshold indicated by the WHO and Brazilian Health Ministry. The average δ13C and δ15N values in Matamata samples were -31.7‰ and 11.9‰, respectively. The principal energy source sustaining the food chain of C. fimbriata was found to be terrestrial shrubs, with smaller contributions from emergent aquatic herbaceous plants and algae, while δ15N values showed its trophic position to be two levels above the autotrophic energy sources. There was a positive correlation between THg and turtle size, while a significant relationship was found between THg and δ15N, showing strong biomagnification in the food chain of C. fimbriata: y = 0.21x + 0.46; r2 = 0.45; p < 0.001, for which the slope presented a value of 0.21.

Mercury biomagnification in the food web of Agami Pond, Kaw-Roura Nature Reserve, French Guiana

Freshwater ecosystems are among the most important ecosystems worldwide, however, over the last centuries, anthropogenic pressures have had catastrophic effects on them. Mercury (Hg) is one of the main environmental contaminants which globally affect ecosystems and particularly freshwater wildlife. While Hg originates from natural sources, anthropogenic activities such as agriculture, biomass combustion, and gold mining increase its concentrations.Gold mining activities are the main drivers of Hg emission in tropical ecosystems and are responsible for up to 38% of global emissions. Once in its methylated form (MeHg), mercury biomagnifies through the trophic chain and accumulates in top predators. Due to the toxicity of MeHg, long-lived predators are even more subjected to chronic effects as they accumulate Hg over time.In the present study we quantified Hg contamination in two top predators, the Black caiman Melanosuchus niger and the Agami heron Agamia agami, and in their prey in the Kaw-Roura Nature Reserve in French Guiana and evaluated the biomagnification rate in the trophic chain.Our results show that despite a TMF in the range of others in the region (4.38 in our study), top predators of the ecosystem present elevated concentrations of Hg. We have found elevated Hg concentrations in the blood of adult Black caiman (2.10 ± 0.652 μg g−1 dw) and chicks of Agami heron (1.089 ± 0.406 μg g−1 dw). These findings highlight the need to better evaluate the potential impact of Hg in freshwater top predators, especially regarding reprotoxic effects.

Unveiling the Sources and Transfer of Mercury in Forest Bird Food Chains Using Techniques of Vivo-Nest Video Recording and Stable Isotopes.

Knowledge gaps in mercury (Hg) biomagnification in forest birds, especially in the most species-rich tropical and subtropical forests, limit our understanding of the ecological risks of Hg deposition to forest birds. This study aimed to quantify Hg bioaccumulation and transfer in the food chains of forest birds in a subtropical montane forest using a bird diet recorded by video and stable Hg isotope signals of biological and environmental samples. Results show that inorganic mercury (IHg) does not biomagnify along food chains, whereas methylmercury (MeHg) has trophic magnification factors of 7.4-8.1 for the basal resource-invertebrate-bird food chain. The video observations and MeHg mass balance model suggest that Niltava (Niltava sundara) nestlings ingest 78% of their MeHg from forest floor invertebrates, while Flycatcher (Eumyias thalassinus) nestlings ingest 59% from emergent aquatic invertebrates (which fly onto the canopy) and 40% from canopy invertebrates. The diet of Niltava nestlings contains 40% more MeHg than that of Flycatcher nestlings, resulting in a 60% higher MeHg concentration in their feather. Hg isotopic model shows that atmospheric Hg0 is the main Hg source in the forest bird food chains and contributes >68% in most organisms. However, three categories of canopy invertebrates receive ∼50% Hg from atmospheric Hg2+. Overall, we highlight the ecological risk of MeHg exposure for understory insectivorous birds caused by atmospheric Hg0 deposition and methylation on the forest floor.

Contrasting trophic transfer patterns of cadmium and mercury in the Arctic marine food web of east Hudson Bay, Canada

We investigated trophic transfer of cadmium (Cd) through an Arctic marine food web in Hudson Bay and compared it with mercury (Hg), a metal known to strongly biomagnify. We evaluated blue mussel, sea urchin, common eider, sculpin, Arctic cod, and ringed seal for the influence of dietary and biological variables on variation in Cd and Hg concentrations. Age and size influenced metal concentrations among individuals within a vertebrate species. Consumer carbon and sulfur isotope values were correlated with their Cd and Hg concentrations, indicating habitat-specific feeding influenced metal bioaccumulation. Trophic transfer patterns for Cd depended on the vertebrate tissue, with food web biodilution observed for the muscle but not the liver. Liver Cd concentrations were higher in ringed seal and some common eider relative to prey. In contrast, we observed mercury biomagnification for both tissues. Tissue- and species-specific physiology can explain discrepancies of Cd trophic transfer in this Arctic marine food web.

Compound-specific stable nitrogen isotope analysis of amino acids shows that bulk methods provide higher estimates of mercury biomagnification in the Gulf of St. Lawrence

Compound-specific stable isotope analysis of amino acids (CSIA-AA) provides a method to estimate baseline δ15N values of food chains, allowing less biased estimates of trophic positions for organisms. Greater accuracy in trophic positions can improve estimates of contaminant biomagnification. We calculated trophic positions with various CSIA-AA equations for four species of fish and northern gannets (Morus bassanus) from the Gulf of St. Lawrence. We examined the effect of CSIA-AA-derived trophic positions on mercury biomagnification metrics (trophic magnification factors (TMF) and biomagnification factors) and compared these with trophic position estimates and metrics obtained from traditional bulk stable isotope analysis. The TMFs for the CSIA-AA equations ranged from 10 to 19, and bulk stable isotope analysis produced TMFs of 43, one of the highest TMFs recorded yet in the literature. Biomagnification factors between prey and northern gannets ranged from 20 to 42 using dietary observations and stable isotope mixing models. Our study demonstrates that discrepancies in biomagnification assessed using different approaches may go undetected when using a single approach.

Mercury distribution in fish organs sampled along the Mauritanian Atlantic coast and their potential human health risks

This paper aimed at assessing total mercury concentration in seven common fish species (Auxis rochei, Caranx rhonchus, Sardina pilchardus, Sardinella aurita, Sardinella maderensis, Scomber colias and Trachurus trecae) and a relationship between Hg organotropism and food regimes along the Mauritanian Atlantic coast. Results show that total mercury concentration in fish collected along five sites ranged from 0.027 to 0.533 mg/kg dry weight. Significant differences were observed among species depending on feeding behavior. Muscle tissues of carnivorous fish presented significantly higher levels of total mercury than that of omnivorous fish, except for Scomber colias, suggesting mercury biomagnification through the food chain. Significant differences in mercury concentrations were observed between muscle tissues and liver, for Auxis rochei, Trachurus trecae, and Caranx rhonchus.The mean concentrations in the different species are however low and none of the concentration values exceed the World Health Organization's threshold for human consumption.

Bioconcentration, bioaccumulation and biomagnification of mercury in plankton of the Mediterranean Sea

Plankton plays a prominent role in the bioaccumulation of mercury (Hg). The MERITE-HIPPOCAMPE campaign was carried out in spring 2019 along a north-south transect including coastal and offshore areas of the Mediterranean Sea. Sampling of sea water and plankton by pumping and nets was carried out in the chlorophyll maximum layer. Two size-fractions of phytoplankton (0.7–2.7 and 2.7–20 μm) and five of zooplankton (between 60 and >2000 μm) were separated, and their total mercury (THg) and monomethylmercury (MMHg) contents were measured. Bioconcentration of THg was significantly higher in the smallest phytoplankton size-fraction dominated by Synechococcus spp. The bioaccumulation and biomagnification of MMHg in zooplankton was influenced by size, food sources, biochemical composition and trophic level. MMHg was biomagnified in the plankton food web, while THg decreased toward higher trophic levels. Higher MMHg concentrations were measured in oligotrophic areas. Plankton communities in the Southern Mediterranean Sea had lower MMHg concentrations than those in the Northern Mediterranean Sea. These results highlighted the influence of environmental conditions and trophodynamics on the transfer of Hg in Mediterranean plankton food webs, with implications for higher trophic level consumers.

Metal-specific biomagnification and trophic dilution in the coastal foodweb of the California sea lion (Zalophus californianus) off Bahía Magdalena, Mexico: The role of the benthic-pelagic foodweb in the trophic transfer of trace and toxic metals

Trace metals concentrations along with stable isotopes ratios were measured in marine algae, sea grass, sponges, echinoderms, mollusks, crustaceans, fishes, and the California sea lion, to assess the bioaccumulation potential and detect potential risks for top predators off Bahia Magdalena, Mexico. We assessed the trophic magnification factor (TMF) to determine the potential for biomagnification of 11 trace metals. The concentrations of Fe and Zn were one order of magnitude higher than all other metals. Concentrations of As, Cu, Cd, Co, Cr, Fe, Mn and Ni correlated negatively with trophic level, supporting trophic dilution (TMF < 1, p > 0.05), while Zn and Hg had significant trophic magnification (TMF > 1, p < 0.05) when assessing only the benthic-pelagic foodweb. This research provides a baseline concentration of metals in multiple species, metal-specific foodweb bioaccumulation and biomagnification of mercury, underscoring the key role of the macrobenthic community as biovectors for trophic transfer of Hg through the foodweb to the California sea lion.

Mercury biomagnification and trophic structure patterns in neotropical coastal estuaries impacted by a Chlor-alkali plant in northeast Brazil

The present study reports the concentration of HgT and MeHg in sediments and food webs in estuarine and coastal areas of Northeast Brazil, which have been subject to different impacts, mainly by chlorine and alkali companies. The results showed that the HgT in the sediment varied from 1.7 to 1186 ng g−1 and from 3.3 to 2163 ng g−1 in the organisms. A strong positive relationship between the levels of Hg in the sediment and the organisms was detected. Methylmercury represented 42 to 99% in the muscles of fish and invertebrates. Biomagnification processes were identified for all study areas evaluated according the trophic magnification factor (TMF), which ranged from 3.1 to 12.3. We found significant negative correlations with δ13C values and mercury concentrations and positive correlations between δ15N values and mercury, typical of Hg trophodynamics. This suggests a direct impact of the level of site-specific contamination on local food web and the ecosystem, making continuous monitoring studies necessary to assess food security and the risks that the riverine community is exposed as a result of ingesting mercury contaminated fish.

Understanding trophic transference role in mercury biomagnification and bioaccumulation in the Atlantic spotted dolphin (Stenella frontalis)

Mercury is a metal of toxicological importance that occurs naturally. However, its concentration can be affected by anthropogenic activities and has the potential to bioaccumulate and biomagnify in food webs. Thus, knowing how its concentration varies along the trophic levels allows us to understand its potential risks to the biota. The present study aimed to investigate mercury transfer through the Stenella frontalis food web in Ilha Grande Bay (IGB), Rio de Janeiro state, Brazil. Samples of muscle and liver of S. frontalis were obtained from carcasses (n = 8) found stranded in the IGB, and its potential prey species were collected in fishing landings in the same Bay (n = 145). Total mercury (THg) concentrations were determined by atomic absorption spectrometry, and the δ15N was determined by an isotope ratio mass spectrometer. To investigate how trophic transfer affects mercury contamination in biota, six linear models were applied between THg logarithmic concentrations and δ15N or trophic position (TP). The trophic magnification factor (TMF) was calculated from each model to estimate the trophic transfer. Mean THg concentration in S. frontalis was higher in the liver than in muscle, but no correlation was found with age and δ15N values. Instead, the hepatic and muscular THg concentrations positively correlated with the trophic position. In the summer, THg concentration, TP, and δ15N values in prey species varied significantly, as well as in the winter, except for THg concentration. All trophic transfer models were significant in both seasons, and the TMF >1. The present study showed that trophic transfer is an essential factor in mercury biomagnification in both seasons but is not the unique driver. Both δ15N and TP could explain mercury trophic transfer, but TP better integrates metabolic diversity and seasonality.

Analysis of Liver Histology Several Fish in the Air Kotok River in the Gold Mining Area, Lebong Regency

Fish have habitats that are easily exposed to contamination from the environment such as heavy metal waste which can cause changes in the structure and function of body tissues. One type of waste that enters the river in the Lebong Regency River is gold mining processing waste that uses mercury and cyanide. Heavy metals can enter organisms and accumulation and biomagnification of mercury can occur in the bodies of aquatic biota such as fish. There has been no research related to fish histology in the Lebong gold mining area, so the aim of this research was to determine the histological condition of the liver organs of several fish in the form of Hemibagrus nemurus, Rasbora sp, Trichogaster trichopterus, and Macrognathus circumcinctus in the Air Kotok river in the gold mining area of Lebong Regency. The research was conducted using the paraffin method with hematoxylin-eosin staining. Data were analyzed descriptively qualitatively based on the histology of the fish liver. The results of the research on the liver histology, it shows damage to the fish liver structure which includes vacuolization, congestion, pyknosis, dilated sinusoids, melanomacrophages and leukocyte infiltration. The damage to the hepatocytes of this fish can be used as a bio-indicator of exposure to toxic substances in the Air Kotok river, one of which is heavy metal activity from gold mining, which can be a threat to the health and survival of the fish.Keywords: Bengkulu, gold mining waste, heavy metal, hepa

Mercury Contamination of an Introduced Generalist Fish of Intermediate Trophic Level.

Mercury contamination is a global issue because mercury concentrations in aquatic systems are influenced by both natural and anthropogenic pathways. Here, liver and muscle total mercury (THg) concentrations in black crappie Pomoxis nigromaculatus from three boreal lakes in southeastern Manitoba, Canada, were related to age, morphology and physiological traits to better understand the dynamics of mercury accumulation in an introduced generalist fish species. These THg concentrations were then compared to black crappie mercury concentrations in other Canadian water bodies and to mercury concentrations in other freshwater fishes in southeastern Manitoba. Age and size had strong positive correlations (P < 0.001, r ≥ 0.60) with muscle mercury concentrations. No evidence of acute point source contamination or physiological impairment in black crappie was found in the study area. Analysis of liver THg revealed the possible impacts of seasonal and ontogenetic differences in diet on exposure. Furthermore, THg analysis of liver and muscle tissue showed how generalist foraging may curb the progressively greater mercury exposure and resultant physiological consequences expected from ontogenetic diet shifts in black crappie. Although there appeared to be temporally varied levels of mercury exposure (i.e., liver THg) by sex, there was no sex effect observed in long-term mercury accumulation in the muscle. Black crappie bioaccumulated less mercury at age than primary piscivore species in the region. These results will help foster a better understanding of mercury biomagnification within a region impacted by legacy mercury.

Bioaccumulation and trophic transfer of total mercury through the aquatic food webs of an African sub-tropical wetland system

Anthropogenic activities, including combustion of fossil fuels, coal, and gold mining, are significant sources of mercury (Hg) emissions into aquatic ecosystems. South Africa is a major contributor to global Hg emissions (46.4 tons Hg in 2018), with coal-fired power stations as the main source. Atmospheric transport of Hg emissions is the dominant cause of contamination, especially on the east coast of southern Africa where the Phongolo River Floodplain (PRF) is located. The PRF is the largest floodplain system in South Africa, with unique wetlands and high biodiversity, and provides essential ecosystem services to local communities who rely on fish as a protein source. We assessed the bioaccumulation of Hg in various biota, the trophic positions and food webs, as well as the biomagnification of Hg through the food webs in the PRF. Elevated Hg concentrations were found in sediments, macroinvertebrates and fish from the main rivers and associated floodplains in the PRF. Mercury biomagnification was observed through the food webs, with the apex predator tigerfish, Hydrocynus vittatus, having the highest Hg concentration. Our study shows that Hg in the PRF is bioavailable, accumulates in biota and biomagnifies in food webs.

Selenium in the liver facilitates the biodilution of mercury in the muscle of Planiliza haematocheilus in the Jiaozhou Bay, China

There are increasing evidences that the biodilution effect can significantly reduce the biomagnification of mercury (Hg) in fish. The significant antagonism of selenium (Se) -Hg may have a potential diluting effect on Hg in fish; however, there is still lack of knowledge on such effect. To reveal the Se-Hg interaction and its role in controlling the biodilution effect of Hg, we investigated levels of Hg and Se in the muscle and liver of redlip mullet from Jiaozhou Bay, China, an urbanized semi-enclosed bay highly impacted by human activities. In general, Hg levels in fish muscle were significantly negatively correlated to the levels of Se in the liver and fish size for fish with a size of < 200 mm, indicating that the antagonistic effect of Se on Hg increased with fish growth. This relationship was not significant for fish with a size of > 200 mm, possibly because the normal metabolism of Hg in muscle was hindered by homeostatic regulation or physiological activities such as gonadal development in vivo. Furthermore, the molar ratio of Se in the liver/Hg in the muscle was significantly increasing with Se/Hg in the liver, suggesting that the liver may be the key organ involved in Se-Hg antagonism. Moreover, both ratios continued to decrease with increasing fish size, implying that the antagonistic effect weakens with fish growth. These results indicate that Hg sequestration by liver may be a key mechanism of Se-Hg antagonism in fish and function as a driver for the biodilution effect of Hg, especially at a size of < 200 mm. These findings are further supported by the established linear model of Se-Hg antagonism at different developmental stages.

Mercury biomagnification at higher rates than the global average in aquatic ecosystems of the Qinghai-Tibet Plateau

Mercury biomagnification in aquatic ecosystems is a global issue. Biomagnification patterns and drivers in alpine regions remain poorly understood. Hg biomagnification in the aquatic food web of the Qinghai-Tibetan Plateau (Q-T Plateau) was investigated. A total of 302 fish and macroinvertebrate tissue samples were analysed for total mercury (THg) and nitrogen (δ15N) stable isotope ratios. Overall, 26.75% of fish individuals exceeded the USFWS consumption guidelines. A total of 52.17% of the sampling sites covering different habitats exhibited a significantly positive THg–δ15N relationship, which confirmed the Hg biomagnification potential of Q-T Plateau aquatic ecosystems. The Q-T Plateau Hg biomagnification rates were generally far higher than global averages regardless of the habitat type. Hg in sediments, elevation and population density were positively related to the Hg biomagnification magnitude on the Q-T Plateau, which could be attributed to the disproportionate response of Hg concentrations in macroinvertebrates and fishes along environmental gradients. Our findings offer empirical evidence that fish consumption on the Q-T Plateau poses a substantial Hg exposure risk to people living along river and lake shores. Higher biomagnification rates could further disproportionately accelerate Hg pollution in Q-T Plateau aquatic ecosystems under future anthropogenic activities and climate warming trajectories.

Understanding Trophic Transference Role in Mercury Biomagnification and Bioaccumulation in the Atlantic Spotted Dolphin (Stenella Frontalis)

Understanding Trophic Transference Role in Mercury Biomagnification and Bioaccumulation in the Atlantic Spotted Dolphin (Stenella Frontalis)

Trophic structure and biomagnification of cadmium, mercury and selenium in brown smooth hound shark (Mustelus henlei) within a trophic web

Stable isotopic values of carbon (δ13C) and nitrogen (δ15N) were used to characterize the trophic structure and biomagnification of Cadmium (Cd), Mercury (Hg) and Selenium (Se) in a trophic web of 18 taxa namely zooplankton, crustaceans, mollusks, fishes, and Mustelus henlei shark collected off the western coast of Baja California Sur, Mexico. Isotopic results indicated interspecies variations in the trophic web structure with mean δ13C values of – 20.0‰ (zooplankton) < − 18.2 ‰ (M. henlei) < − 14.1 ‰ (Thaisella kiosquiformis, mollusk). In general, δ15N and δ13C values increased from primary consumers (zooplankton) to predators, following the isotopic patterns of other trophic webs. The concentrations of Cd, Hg and Se were relatively less in most of the organisms except mollusks that presented high concentrations of Cd. The biomagnification factors of the trophic web showed biodilution of Cd (Food Web Magnification Factor, FWMFCd = 0.2), biomagnification of Hg (FWMFHg = 3.34) and Se (FWMFSe = 1.45) respectively. However, the concentrations of Se did not increase consistently from the lower trophic levels to the higher ones. This study documents the dynamics of a marine trophic structure and demonstrates that biodilution/biomagnification processes of metal contaminants are largely species specific and are closely related to physical - chemical and food web structure.

Estimates, spatial variability, and environmental drivers of mercury biomagnification rates through lake food webs in the Canadian subarctic

Biomagnification of mercury (Hg) through lake food webs is understudied in rapidly changing northern regions, where wild-caught subsistence fish are critical to food security. We investigated estimates and among-lake variability of Hg biomagnification rates (BMR), relationships between Hg BMR and Hg levels in subsistence fish, and environmental drivers of Hg BMR in ten remote subarctic lakes in Northwest Territories, Canada. Lake-specific linear regressions between Hg concentrations (total Hg ([THg]) in fish and methyl Hg ([MeHg]) in primary consumers) and baseline-adjusted δ15N ratios were significant (p < 0.001, r2 = 0.58–0.88), indicating biomagnification of Hg through food webs of all studied lakes. Quantified using the slope of Hg-δ15N regressions, Hg BMR ranged from 0.16 to 0.25, with mean ± standard deviation of 0.20 ± 0.03). Using fish [MeHg] rather than [THg] lowered estimates of Hg BMR by ∼10%, suggesting that the use of [THg] as a proxy for [MeHg] in fish can influence estimates of Hg BMR. Among-lake variability of size-standardized [THg] in resident fish species from different trophic guilds, namely Lake Whitefish (Coregonus clupeaformis) and Northern Pike (Esox lucius), was not significantly explained by among-lake variability in Hg BMR. Stepwise multiple regressions indicated that among-lake variability of Hg BMR was best explained by a positive relationship with catchment forest cover (p = 0.009, r2 = 0.59), likely reflecting effects of forest cover on water chemistry of downstream lakes and ultimately, concentrations of biomagnifying MeHg (and percent MeHg of total Hg) in resident biota. These findings improve our understanding of Hg biomagnification in remote subarctic lakes.

Mercury biomagnification in a coastal Louisiana food web following the 2010 Deepwater Horizon oil spill

The estuarine environments surrounding coastal Louisiana create favorable conditions for microbially mediated mercury (Hg) methylation and subsequent bioaccumulation by biota. In 2010, the Deepwater Horizon (DWH) oil spill released large amounts of oil which, despite having low Hg concentrations, had the potential to influence methylmercury (MeHg) bioavailability in the coastal zone. To explore this possibility, we assessed Hg concentrations and trophodynamics in the coastal Louisiana food web prior to and immediately following the DWH oil spill and compared these metrics with an adjacent coastal ecosystem in the northern Gulf of Mexico. We found no differences in MeHg concentrations between oysters collected in years prior to the spill (1986–2007) and those collected during or in the months immediately after the spill (May to December 2010). When comparing tissue MeHg concentrations and carbon and nitrogen stable isotope values across 13 species of bivalves, shrimp, crabs, fishes, and birds we found evidence of significant biomagnification within the coastal Louisiana food web driven by species’ trophic position and their use of differing basal carbon sources. In addition, Hg trophodynamics also differed between two adjacent coastal ecosystems, post-spill coastal Louisiana (2010) and pre-spill coastal Alabama (2008–2009). While there was a higher trophic magnification factor in coastal Louisiana relative to coastal Alabama, food web baseline MeHg concentrations were higher in coastal Alabama. The high degree of biomagnification in coastal Louisiana, and significant regional variation, underscores the need to monitor Hg trophodynamics over space and time to better evaluate the short and long-term ecological consequences of events like the DWH oil spill.