1. Spatial and temporal trophic transfer dynamics of mercury and methylmercury into zooplankton and phytoplankton of Long Island Sound.
- Author
-
Gosnell, Kathleen J., Balcom, Prentiss H., Tobias, Craig R., Gilhooly, William P., and Mason, Robert P.
- Subjects
- *
METHYLMERCURY , *ZOOPLANKTON , *PHYTOPLANKTON , *BIOACCUMULATION - Abstract
The foundation of methylmercury (MeHg) bioaccumulation in aquatic systems is uptake and trophic transfer into phytoplankton and zooplankton. Phytoplankton and zooplankton samples were collected seasonally from Long Island Sound (LIS) and its adjacent shelf waters, located along the northeast coast of the United States. Phytoplankton samples were size fractioned into 0.2-5 μm, 5-20 μm, and seston of > 20 μm. Average phytoplankton MeHg concentrations were 0.01-1.5 pmol g−1 (wet weight), and MeHg bioconcentration factors (logBCF) ranged from 2.5 to 5.5. There was higher MeHg concentration and logBCF values with increasing phytoplankton size. Zooplankton samples were size fractioned into 0.2-0.5 mm, 0.5-1.0 mm, 1.0-2.0 mm, and > 2.0 mm classes and analyzed for Hg and MeHg as well as carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotopes. The %MeHg in organisms was highest in the > 2.0 mm size class for coastal LIS and shelf species, indicating higher MeHg bioaccumulation with increasing zooplankton sizes. Eastern LIS zooplankton populations yielded higher overall Hg accumulation than western LIS populations, in alignment with phytoplankton fractions. Seasonal differences were evident for plankton %MeHg, although only ELIS displayed an increase in summertime %MeHg throughout the fractions. The results suggest the importance of biodilution in determining plankton MeHg concentrations. The δ13C values infer that zooplankton were opportunistically feeding on food containing variable levels of Hg and MeHg. The δ15N isotopes indicated enrichment characteristic of anthropogenic input in populations at the western end of LIS. The δ34S isotopes signified that organisms were primarily feeding on pelagic plankton. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF