“Differing Foraging Strategies Influence Mercury (HG) Exposure in an Antarctic Penguin Community”

This Friday, March 17, 2017 the College of the Coast & Environment will be hosting Dr. Rebecka Brasso, Southeast Missouri State University. Dr. Brasso’s topic for the seminar will be “Differing foraging strategies influence mercury (Hg) exposure in an Antarctic penguin community.” Please join us in the Dalton J. Woods Auditorium for this very informative talk.

Abstract:

Differing foraging strategies influence mercury (Hg) exposure in an Antarctic penguin community

Remote regions such as the Antarctic have become increasingly important for investigations into far-reaching anthropogenic impacts on the environment, most recently in regard to the global mercury (Hg) cycle. Pygoscelis penguins are ideal model organisms to track Hg through the Antarctic marine food web as they are long-lived, broadly distributed, and are susceptible to biomagnification due to foraging at relatively high trophic levels. However, using these species as biomonitors requires a solid understanding of the degree of species-specific variation in foraging behaviors act to mediate their dietary exposure to Hg. We combined stomach content analysis along with Hg and stable isotope analyses of eggshell membrane, blood, feathers and common prey items to help explain inter and intra-specific patterns of dietary Hg exposure. Breeding colonies were sampled from four of the major regions of the Antarctic Peninsula to address spatial variation in Hg exposure and diet. In addition, a long-term data set from a single colony where all three species breed sympatrically was used to examine inter-annual variation in Hg and diet. Hg concentrations did not vary significantly among regions of the Antarctic Peninsula and remained fairly consistent over the eight year time period investigated. Hg concentrations did differ significantly among species; Hg concentrations in Chinstrap (Pygoscelis antarctica) penguins were significantly higher than concentrations in Gentoo (P. papua) and Adelié (P. adeliae) penguins. Stable isotope analysis revealed diets of all three species to be dominated by Antarctic krill (Euphausia superba) and to a lesser extent fish. Integrating isotopic approaches with stomach content analysis allowed us to identify species-specific preferences for prey fish insufficiently explained by stable isotope proxies for trophic level. Chinstrap penguins were found to forage on a larger proportion of higher Hg mesopelagic prey fish relative to their congeners targeting epipelagic or benthic prey species. While the potential for adverse effects due to Hg exposure is currently low in Pygoscelis penguins in the Antarctic Peninsula, this approach allowed us to substantiate for the first time, the relatively higher risk of Hg exposure for Chinstrap penguins.

Lunch will be provided immediately following the seminar in the conference room next to the auditorium.

Time: 11:30 a.m. – 12:15 p.m.
Where: Dalton J. Woods Auditorium
LSU Energy, Coast, and Environment Building