March 29 Brown Bag Lunch

“Interactions of fish ecology, migration history, food web structure, and mercury bioaccumulation in coastal Arctic lakes”

Presenters

  • Heidi Swanson, PhD

Date

Monday, March 29, 2010, 12:00 – 1:00 p.m.

Location

Golder (#300, 10525 – 170 St)

Description

Heidi Swanson, PhD studied fish migration, fish ecology, food web structure, and mercury (Hg) accumulation in six lakes in the West Kitikmeot region of Nunavut, Canada, during 2006-2008. Three lakes contained partially anadromous populations of Arctic charr (Salvelinus alpinus) whereas three lakes contained no Arctic charr. Through analyses of otolith microchemistry and stable carbon (C;δ13C), nitrogen (N;δ15N), and sulfur (S;δ34S) isotope ratios, I discovered that lake trout (Salvelinus namaycush) can adopt a partially anadromous life history strategy. Anadromous lake trout had significantly higher condition factors and C:N than resident lake trout, and anadromous lake trout began migrating to sea at a significantly older age (mean=13 years) than anadromous Arctic charr (mean=5 years). In contrast to results from freshwater habitats that support anadromous Pacific salmon species, stable isotope analysis did not indicate that significant amounts of marine-derived nutrients are imported into lakes via anadromous Arctic charr. However, resident lake trout were in significantly better condition and had significantly higher C:N in lakes where anadromous Arctic charr were present. Fish mercury concentrations ([Hg]) depended on species, life history type, and whether anadromous Arctic charr were present. Lake trout had significantly lower [Hg] than Arctic charr, anadromous lake trout had significantly lower [Hg] than resident lake trout, and resident lake trout had significantly lower [Hg] in lakes where anadromous Arctic charr were present. Differences in [Hg] were best explained by age-at-size, fish condition, C:N, and Hg biomagnification through food chains. Results of this study illustrate the ecological importance of anadromous Arctic charr in freshwater lakes, and have implications for fish conservation, stock management, and fish-derived Hg intake in humans.

Mark your Calendars for this Free Talk

Members and Non-Members Welcome-Bring Your Lunch!


If you cannot make it in person please contact Angela Holzapfel for information of how to participate remotely

Reminder to ASPB members: 
attending brown bag lunches is just one of the ways 
you can accumulate credits for the CCP!