Fish ecology on the boreal plains and western arctic

点击翻译按钮获取中文摘要

In northwestern Canada, freshwater fishes face ecological constraints, disturbances and opportunities. How they affect fish species, populations, and communities is the focus of my NSERC-supported research program. (1)A dominant natural disturbance is "winterkill" caused by low oxygen under the ice. To test if this disturbance is dependent on the location (position) of lakes in a landscape, we will analyze relations between fish occurrence and indices of lake position. (2)Fathead minnows frequently dominate winterkill-prone lakes, but infrequently co-occur with predatory northern pike. Why? Minnows respond behaviourally to chemical signals of pike predation in ways that increase short-term survival, but may affect longer-term survival and reproduction. We will conduct a replicated pond experiment to assess population-level costs to minnows of short-term anti-predator behaviours. (3)In addition to direct effects of predation, minnows co-occurring with pike also differ in life history traits from those in lakes lacking pike. To determine if this reflects a genetic or ecological response, we are conducting a "common garden" experiment that involves raising fish from the two types of populations in adjacent ponds and comparing reproduction and recruitment. (4)Stocking sportfish into lakes adds a non-native predator that can have severe consequences to some lake communities. We are using provincial stocking programs as whole-lake experiments to understand what factors can buffer communities against negative stocking effects. (5)In some Canadian lakes, > 1 variety of a single species co-occur that differ in their morphology and ecology. Surveys in Great Bear Lake suggest that up to 4 varieties of lake trout co-occur in shallow water habitats. We will quantify the morphological differences of these varieties, and determine if they also differ in their ecology and life history. Learning how fish cope with such environmental challenges can help management agencies deal with human-caused disturbance (e.g., cattle grazing adjacent to prairie streams) and the conservation of rare species and varieties that live in such environments.