The short-term stress response of three-spined sticklebacks to climate-related stressors: a mesocosm study

Fish in northern European lakes must cope
with climate change, including frequent extreme
weather events, and eutrophication. In terrestrial
vertebrates the disruption of local environmental
stability can evoke a stress response, with potentially
adverse outcomes for growth, reproduction and survival,
but the effect of extreme weather events on
aquatic vertebrates is not understood. As part of a
mesocosm scale multiple-stressor study we investigated
(i) whether three-spined sticklebacks (Gasterosteus
aculeatus L.) exhibited an acute stress response
(by measuring the steroid hormone cortisol) to simulated
rainfall events, and (ii) whether any such
response was modified by elevated temperature and
nutrient concentrations. On two occasions, sticklebacks
were sampled 1 h and 24 h following the
simulated rainfall event. Cortisol levels were elevated
within 1 h of the rainfall event in November in fish
from heated tanks (with and without nutrient
augmentation). In May, cortisol increased within 1 h
of the rainfall event but only in fish from nutrientenriched
mesocosms (heated and unheated). Cortisol
had declined to control levels within 24 h on both
occasions. This outcome suggests that the acute effect
on fish of transient stressors, such as extreme rainfall
events, may be modified by other environmental
factors, but that interactions between these variables
may be difficult to predict.