Effect of trophic position on mercury concentrations in bottlenose dolphins (Tursiops truncatus) from the northern Gulf of Mexico

McCormack, Meaghan A.; Nowlin, Weston H.; Dutton, Jessica

doi:10.1016/j.envres.2021.112124

Cited by 5 publications

(2 citation statements)

References 89 publications

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“…Lastly, the R package tRophicPosition (Quezada‐Romegialli et al, 2018; Table 3) incorporates a Bayesian approach to estimate the trophic position of consumers and allows the use of isotopic information of up to two baselines (e.g., benthic and pelagic primary producers). This approach has recently been used to assess whether differences in trophic position among bottlenose dolphins from the northern Gulf of Mexico contributed to the mercury concentrations in skin samples (McCormarck et al, 2022).…”

Section: Methodsmentioning

confidence: 99%

A practical guide on stable isotope analysis for cetacean research

Teixeira

Troina

Daura‐Jorge

et al. 2022

Marine Mammal Science

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Trophic ecology information about cetaceans is essential to understand their role in ecosystem dynamics. Stable isotope analysis is a valuable complementary approach to conventional methods usually applied to the study of the foraging behavior of cetaceans because it provides dietary information over different time scales and can potentially use tissues archived in scientific collections. However, the considerable increase in stable isotope analysis by a growing number of cetacean research groups demands the use of proper protocols to ensure that accurate isotopic data are obtained. We provide a theoretical background of stable isotope analysis and its application to assess cetaceans‘ trophic ecology. We review the factors that can influence isotopic measurements and propose a practical guideline with suitable techniques for sample preparation of biological tissues to be employed by researchers to yield reliability in the interpretation of isotopic data. We summarized the main assumptions and inherent limitations that can lead to confounding interpretations of isotopic data, such as species‐ and tissue‐specific discrimination factors, temporal or spatial variation in prey, and baseline isotopic values in the context of cetacean ecology. Our detailed review offers important guidance for researchers who want to use stable isotope analysis to address different ecological questions with cetacean species.

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Section: Methodsmentioning

confidence: 99%

A practical guide on stable isotope analysis for cetacean research

Teixeira

Troina

Daura‐Jorge

et al. 2022

Marine Mammal Science

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“…Differences in contaminant concentrations among reproductive females may result in variation in the contaminant load transferred to offspring and their subsequent risk of adverse health effects. Individual variation in contaminant concentrations can result from different foraging behaviors that are associated with regional and temporal differences in contaminant exposure from prey 1 , 15 – 20 . Furthermore, maternal age 16 , 21 and whether or not females have previously produced offspring 22 , 23 may also contribute to variability in individual maternal contaminant concentrations.…”

Section: Introductionmentioning

confidence: 99%

Foraging behavior and age affect maternal transfer of mercury to northern elephant seal pups

Peterson,

Ackerman

et al. 2024

Sci Rep

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Deep ocean foraging northern elephant seals (Mirounga angustirostris) consume fish and squid in remote depths of the North Pacific Ocean. Contaminants bioaccumulated from prey are subsequently transferred by adult females to pups during gestation and lactation, linking pups to mercury contamination in mesopelagic food webs (200–1000 m depths). Maternal transfer of mercury to developing seal pups was related to maternal mercury contamination and was strongly correlated with maternal foraging behavior (biotelemetry and isotopes). Mercury concentrations in lanugo (hair grown in utero) were among the highest observed worldwide for young pinnipeds (geometric mean 23.01 μg/g dw, range 8.03–63.09 μg/g dw; n = 373); thus, some pups may be at an elevated risk of sub-lethal adverse health effects. Fetal mercury exposure was affected by maternal foraging geographic location and depth; mercury concentrations were highest in pups of the deepest diving, pelagic females. Moreover, pup lanugo mercury concentrations were strongly repeatable among successive pups of individual females, demonstrating relative consistency in pup mercury exposure based on maternal foraging strategies. Northern elephant seals are biosentinels of a remote deep-sea ecosystem. Our results suggest that mercury within North Pacific mesopelagic food webs may also pose an elevated risk to other mesopelagic-foraging predators and their offspring.

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Mercury concentrations in Seaside Sparrows and Marsh Rice Rats differ across the Mississippi River Estuary

Bonisoli-Alquati,

Jackson,

Eagles-Smith

et al. 2024

Ecotoxicology

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Mercury (Hg) concentrations and their associated toxicological effects in terrestrial ecosystems of the Gulf of Mexico are largely unknown. Compounding this uncertainty, a large input of organic matter from the 2010 Deepwater Horizon oil spill may have altered Hg cycling and bioaccumulation dynamics. To test this idea, we quantified blood concentrations of total mercury (THg) in Seaside Sparrows (Ammospiza maritima) and Marsh Rice Rats (Oryzomys palustris) in marshes west and east of the Mississippi River in 2015 and 2016. We also tested for a difference in THg concentrations between oiled and non-oiled sites. To address the potential confounding effect of diet variation on Hg transfer, we used stable nitrogen (δ15N) and carbon (δ13C) isotope values as proxies of trophic position and the source of primary production, respectively. Our results revealed that five to six years after the spill, THg concentrations were not higher in sites oiled by the spill compared to non-oiled sites. In both species, THg was higher at sites east of the Mississippi River compared to control and oiled sites, located west. In Seaside Sparrows but not in Marsh Rice Rats, THg increased with δ15N values, suggesting Hg trophic biomagnification. Overall, even in sites with the most elevated THg, concentrations were generally low. In Seaside Sparrows, THg concentrations were also lower than previously reported in this and other closely related passerines, with only 7% of tested birds exceeding the lowest observed effect concentration associated with toxic effects across bird species (0.2 µg/g ww). The factors associated with geographic heterogeneity in Hg exposure remain uncertain. Clarification could inform risk assessment and future restoration and management actions in a region facing vast anthropogenic changes.

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Effect of trophic position on mercury concentrations in bottlenose dolphins (Tursiops truncatus) from the northern Gulf of Mexico

Cited by 5 publications

References 89 publications

A practical guide on stable isotope analysis for cetacean research

A practical guide on stable isotope analysis for cetacean research

Foraging behavior and age affect maternal transfer of mercury to northern elephant seal pups

Mercury concentrations in Seaside Sparrows and Marsh Rice Rats differ across the Mississippi River Estuary

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