Your Link to Muskoka's Water!

Interacting effects of multiple stressors on ecotoxicological thresholds (Ca and Cl ecotoxicology)

Norman Yan (PI/York University)
Arran Brown (MSc/York University)

Lakes in the Muskoka area of Ontario have been undergoing significant declines in calcium, due to interactions of climate change, logging and changes in acid deposition, and increases in chloride, due to applications of road salt and dust suppressants to regional roads. At the same time, lake water temperatures have been increasing. All of these can have combined effects on zooplankton such as water fleas (Daphnia species), which in turn may affect the survival of other animals that feed on them such as fish.

The purpose of this study is

1. to understand the interactive effects on daphniids of low (and declining) calcium, high (and increasing) chloride, and climate warming, and
    
2. to quantify the effects of rising chloride and food (algae) scarcity on critical calcium thresholds for daphniids.

These effects are to be determined on Daphnia species using ecotoxicological methods that have been customized for Muskoka waters.

To date, a MSc student, Arran Brown has been secured for the project, and began his research in May of 2012. In the summer of 2012, Arran will complete training in the culturing and handling of algae and daphniid cultures for use in chronic chloride toxicity assays and other ecotoxicological methods for both algae and Daphnia.

A few pilot studies are proposed to be run by Arran this summer, based on the techniques he is being trained upon. These pilot studies will be used to determine ranges of chloride toxicity, food, and calcium levels for Daphnia, for use in future ecotoxicological experiments.

Update - November 2013

 
Calcium and chloride levels are changing in Muskoka lakes. Calcium levels are generally falling, due to interactions of climate change, logging and changes in acid deposition, while chloride levels are rising mainly near winter maintained roads. These water quality changes may be harmful to animal plankton such as water fleas (Daphnia species), which serve both to remove algae, keeping Muskoka lakes clean, and to feed consumers including fish.

The goals of this study were: (1) to understand the interactive effects on daphniids of low/declining calcium and high/increasing chloride, and (2) to quantify the effects of rising chloride and algae scarcity on critical calcium thresholds for daphniids. To accomplish these goals chronic (14-day) bioassays were conducted, during which a single Ontario daphniid clone was exposed to various combinations of algae and chloride salts in a fully-defined bioassay and culture medium designed to mimic the chemistry of healthy, soft-water lakes in Muskoka, Ontario.

To date, our research suggests that the nutrient status of soft-water lakes should be considered in the assessment of the threat of road salt pollution to freshwater aquatic organisms.