Regional Projections of Climate Change Effects on Thermal Habitat Space for Fishes in Stratified Ontario Lakes CCRR41

Summary

To better understand the effects of projected changes in climate on suitable habitat space for fish in Ontarios inland lakes, models for ice break-up and freeze-up dates and for seasonal open water temperature profiles were joined to project future thermal regimes in a representative stratified lake for each of Ontarios secondary watersheds under future climates using four global climate models (GCMs) under alternate greenhouse gas emissions scenarios. The seasonal availability of preferred temperature habitat in those representative lakes was projected for fishes in three thermal guilds (cold, cool, and warm). The observed 1971 to 2000 climate averages (referred to as norms) were applied as a baseline to assess changes in suitable habitat availability. Both volume and area habitat availability measures were computed. Four measures of seasonal habitat availability by fish type were assessed: (a) the proportion of the year when suitable habitat was available, (b) the proportion of total lake space (volume or area) supporting suitable habitat, averaged over those parts of the year when some suitable space was present, (c) the proportion of suitable lake space available over a yearthe product of (a) and (b), and (d) the proportion of suitable lake space available on the midsummer day when lake surface temperature reached its peak. The results showed different regional response patterns among the three fish types. Coldwater fish such as lake trout will face longer periods in summer confined to ever smaller suitable thermal spaces. Coolwater fish such as walleye will gain more seasonal habitat space in the north of the province while becoming more constricted in southern areas. Warmwater fish such as smallmouth bass will be able to expand northwards regionally and enjoy more suitable space, although if climate warming reaches the upper bounds projected by some GCMs even they will eventually become constricted. Further development of this thermal habitat model is warranted to account for more factors affecting lakes and their fishes and to allow projections for more than one type of lake.

Published Date: April 30, 2014
Publisher: Science and Research Branch, Ontario Ministry of Natural Resources and Forestry
Author: Charles K. Minns, Brian J. Shuter and Simon Fung

Details

Regional Projections of Climate Change Effects on Thermal Habitat Space for Fishes in Stratified Ontario Lakes CCRR41
ISBN: 978-1-4606-4038-8   (PDF) 2.93 MB