You can't see it, but these fish are spreading nutrients all over. (Credit: Tischenko Irena/Shutterstock) There's something in the water around coral reefs. And that something is fish pee. Although you may cringe at the thought of swimming through clouds of urine, coral reefs wouldn't be the same without fishes' urinary benevolence. Fish excretion may be the furthest thing from your mind as you swim through a vibrant coral reef, but it a plays a vital, though underappreciated, role in supporting the diversity of life under the sea. That’s because it contains two important elements: nitrogen and phosphorous. Fish spread them around by ingesting plants and other fish, extracting the nutrients through the digestive process and then excreting them as they swim. From there, the nitrogen and phosphorus go on to feed the algae that sustain corals.
University of Washington ecologist Jacob Allgeier has been studying the importance of fish ...
