Metabolic theory explains latitudinal variation in common carp populations and predicts responses to climate change

Michael J Weber,Michael L Brown,David H Wahl,Daniel E Shoup

doi:10.1890/es14-00435.1

Abstract

Climate change is expected to alter temperature regimes experienced by fishes, which may also alter life history traits. However, predicting population‐level responses to climate change has been difficult. Metabolic theory of ecology has been developed to explain how metabolism controls a variety of ecological processes, including life history attributes. Thus, this theory may be a useful tool for predicting fish population responses to climate change. To understand how climate change may alter freshwater fish life history, we measured population characteristics (e.g., recruitment, growth, body size, and mortality) of 21 North American common carp Cyprinus carpio populations spanning a latitudinal gradient of >2,700 km. We then evaluated (1) how metabolic rates vary with body size and temperature (i.e., metabolic theory of ecology) to interpret latitudinal patterns in life history traits and (2) how predicted increases in annual temperature as a result of climate change may alter metabolism and population characteristics. Common carp growth and mortality decreased whereas fish size and age increased with increasing latitude. Common carp growth rate was 22% faster but mortality was 31% higher for the most southern population compared to the most northern population. Incorporating latitudinal population patterns into metabolic theory of ecology models explained substantial variation in mortality and longevity among populations and suggested that metabolism will increase with temperature according to three global warming scenarios. The greatest metabolic increase occurred at the largest predicted increase in temperature and metabolism increased more for southern populations compared to northern populations. Combined, our findings suggest common carp and other fishes may experience increased growth and metabolic demands but populations may attain smaller body size due to higher mortality in response to climate change.

Highlights

Global climate change and subsequent longterm alterations in water temperatures are anticipated to have substantial effects on aquatic organisms (Magnuson et al 1990, Sharma et al 2007, Carmona-Catot et al 2011)
Latitudinal patterns in animal population characteristics may be reflective of future population responses to a changing climate (Benejam et al 2009, Walther et al 2009) and could be a useful tool to evaluate possible effects of climate change on populations where long-term datasets are lacking
Common carp displayed a wide range of life history traits and population characteristics across populations (Tables 1 and 2)

Summary

Introduction

Global climate change and subsequent longterm alterations in water temperatures are anticipated to have substantial effects on aquatic organisms (Magnuson et al 1990, Sharma et al 2007, Carmona-Catot et al 2011). Latitudinal patterns in animal population characteristics may be reflective of future population responses to a changing climate (Benejam et al 2009, Walther et al 2009) and could be a useful tool to evaluate possible effects of climate change on populations where long-term datasets are lacking. Counter-gradient growth variation (i.e., faster growth at higher latitudes) can result in similar individual body size in northern versus southern latitudes despite lower temperatures and shorter growing seasons (Conover and Present 1990). Despite our poor understanding of latitudinal patterns of most freshwater fishes, understanding relationships between life history traits and latitude has become increasingly important as ecologists attempt to predict future population responses to climate change (Teplitsky et al 2008, Walther et al 2009, Merila 2012)

Methods

Results

Conclusion