Temperature rise improves harvest sustainability in a model system
despite reduction in carrying capacity
Abstract
Stage-structured population models parameterized from benchtop trials of
individual growth, reproduction and survival predicted that temperature
rise should make populations of Daphnia magna more resilient to periodic
harvest perturbation, despite reduced stock abundance. We tested these
predictions under controlled laboratory conditions on 24 populations
maintained under constant levels of food abundance, but subjected to
weekly harvest events over 10 weeks. As predicted, unperturbed Daphnia
populations raised at 15◦C were substantially more abundant by the end
of 10 week trials than those raised at 25◦C, but abundance declined
sharply with harvest intensity and Daphnia populations collapsed
entirely at the highest harvest rate, whereas those populations raised
at 25◦C were little affected by perturbation. Our findings suggest that
projected patterns of climate change should tend to make populations
whose growth rates and rate of maturation increase with temperature
better capable of coping with periodic harvest perturbation, despite
declining levels of abundance.