Life in the north temperate zones requires the ability to endure sometimes_harsh overwinter conditions. For both aquatic and terrestrial organisms, winter can mean a time of drastically reduced food availability as well as increased susceptibility to freezing. For aquatic organisms, winter conditions include reduced oxygen availability that can occur as ice_cover blocks wind-driven mixing of the water and reduces solar radiation, therefore reducing oxygen production by photosynthesis. Organisms have evolved various behavioral and physiological mechanisms to increase their tolerance of these conditions. In order to avoid tissue damage by ice, some organisms possess cryoprotectants that protect them from freezing and some alter their habitat choice by seeking protected overwintering sites. A mechanism that assists organisms to deal with reduced availability of food and oxygen is to reduce their energetic needs.

By reducing rates of metabolism. In this exercise we will: 1) examine organisms in their overwintering sites; 2) conduct an experiment on the effects of solutes on freezing; and 3) explore the effects of temperature on the metabolic rates (oxygen use) of various invertebrates.

Videos:
Overwintering Lecture
Requires Apple's Quicktime software.

Casey Huckins

Casey Huckins is an Assistant Professor in the Department of Biological Sciences at MTU.