Algal blooms impact the quality of nest construction in three-spined sticklebacks

Purpose-built nests for rearing offspring have important fitness consequences. Nests not only provide a protective environment for developing young but also in some species can serve as important signalling devices that reveal crucial information about the quality of the builder. Nesting behaviour and nest structure are often adjusted to suit local environmental conditions. An important question is what happens when conditions are altered as a result of anthropogenic activities. Human-induced eutrophication is an insidious, global problem. Here, we investigated experimentally the impact of algal blooms on nest construction in a fish: the three-spined stickleback, Gasterosteus aculeatus. We found that males took longer to complete their nests under algal conditions. Completed nests were also smaller and possessed wider nest entrances. Together, our results suggest that human-induced algal blooms can have profound effects on nesting behaviour and nest construction, with implications for both offspring survival and the utility of nests as extended phenotypic signals.