Assessing toxicity and bioaccumulation of Hamilton Harbour sediments

Session: 04. - Restoring Hamilton Harbour: Tilting at Windmills or a Possible Dream?

Kathleen Stevack, University of Guelph, [email protected]
Paul Sibley, University of Guelph, School of Environmental Sciences, [email protected]
David Poirier, Ontario Ministry of Environment and Climate Change, [email protected]

Abstract

Contaminated sediment has been identified as one of the major impediments to AOC remediation. In summer 2014 and 2015, Hamilton Harbour sediments were sampled from 3 monitoring stations (mid-Harbour, near Cootes Paradise, and Windermere Arm) to assess toxicity and bioaccumulation. In acute laboratory sediment bioassays for all sites, there was no mortality or growth impairment observed compared to control sediments. Chronic exposures using the midge Chironomus dilutus indicated reproductive impairment for Windermere Arm; with delayed time to emergence, decreased percent emergence, and decreased egg production per replicate.

In laboratory bioaccumulation exposures, total PCB levels in fathead minnow tissue ranged from 240-620 ng/g, exceeding  the CCME sediment Probable Effects Level of 277 ng/g. Sport fish were also sampled in the summer of 2015, with yellow perch averaging 20 ng/g total PCBs, and brown bullhead averaging 190 ng/g. The oligochaete Lumbriculus variegatus was utilized for laboratory assessment of PAH uptake, with tissue concentrations averaging between 25-45 ng/g for sum PAHs. Elevated contaminant tissue concentrations in invertebrates, forage, and sport fish indicate mobilization of these contaminants from the sediments into the food web. These elevated tissue concentrations, in addition to observed chronic toxicity may indicate the need to revisit present delisting targets.

1. Keyword
Hamilton Harbour

2. Keyword
sediment quality

3. Keyword
benthos

4. Additional Keyword
bioaccumulation