But algal blooms triggered by pollution may be hindering fishes’ ability to build these refuges. According to a new study in Animal Behaviour, sticklebacks assemble nests more slowly and make smaller nests in water clouded by algae.
People are releasing nutrients into oceans and lakes, often due to fertilizer run-off from farms. In areas such as the Baltic Sea, these nutrients prompt “the rampant growth of filamentous algae and phytoplankton,” the study authors write. Since male sticklebacks build nests along the Baltic coast, the researchers wanted to find out if the algae explosion affected the fishes’ activity.
The team caught sticklebacks in the Gulf of Finland and transported them to aquariums. Then each male fish was offered the chance to build a nest, once in clear water and once in water with algae.
The males took longer to finish their nests in algae-clouded water, the team reports. In clear water, 70 percent of the male fish completed a nest in less than a day. But in water with algae, that number went down to 47 percent, and the nests were smaller.
The nests in the algae-containing water also had bigger entrances. The wider opening might allow more water to flow through the nest and “prevent algae from settling on, and smothering, the eggs,” the researchers speculate.
One feature of the nests didn’t change: Male sticklebacks like to decorate their nests with red material, so the team provided them with red thread. But the fish were just as likely to spiff up their nests with threads in the clear water as in the algae-containing water. — Roberta Kwok | 3 December 2012
Source: Wong, B.B.M., U. Tuomainen, and U. Candolin. 2012. Algal blooms impact the quality of nest construction in three-spined sticklebacks. Animal Behaviour doi: 10.1016/j.anbehav.2012.09.31.
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