Abstract

Ectotherms are predicted to 'shrink' with global warming, in line with general growth models and the temperature-size rule (TSR), both predicting smaller adult sizes with warming. However, they also predict faster juvenile growth rates and thus larger size-at-age of young organisms. Hence, the result of warming on the size-structure of a population depends on the interplay between how mortality rate, juvenile- and adult growth rates are affected by warming. Here, we use two-decade long time series of biological samples from a unique enclosed bay heated by cooling water from a nearby nuclear power plant to become 5-10 degrees C warmer than its reference area. We used growth-increment biochronologies (12,658 reconstructed length-at-age estimates from 2426 individuals) to quantify how >20 years of warming has affected body growth, size-at-age, and catch to quantify mortality rates and population size- and age structure of Eurasian perch (Perca fluviatilis). In the heated area, growth rates were faster for all sizes, and hence size-at-age was larger for all ages, compared to the reference area. While mortality rates were also higher (lowering mean age by 0.4 years), the faster growth rates lead to a 2 cm larger mean size in the heated area. Differences in the size-spectrum exponent (describing how the abundance declines with size) were less clear statistically. Our analyses reveal that mortality, in addition to plastic growth and size-responses, is a key factor determining the size structure of populations exposed to warming. Understanding the mechanisms by which warming affects the size- and the age structure of populations is critical for predicting the impacts of climate change on ecological functions, interactions, and dynamics.

Keywords

Perca fluviatilis; body growth; size; size-spectrum; mortality; climate change

Published in

eLife
2023, Volume: 12, article number: e82996

SLU Authors

• Lindmark, Max

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Gårdmark, Anna

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Conserve and sustainably use the oceans, seas and marine resources for sustainable development
Take urgent action to combat climate change and its impacts


UKÄ Subject classification

Ecology


Publication identifier

DOI: https://doi.org/10.7554/eLife.82996

Permanent link to this page (URI)

https://res.slu.se/id/publ/123764