As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Wednesday, 24 May 2017

When birds of a feather poop together: Excessive birds feces and algal blooms




Date: May 17, 2017
Source: American Society of Agronomy

Studying the effects of great cormorant droppings on water reservoirs is a dirty job, but someone's got to do it.

At the Maji Agricultural Reservoir in Wonju, Gangwond-do, South Korea, that someone is Tae Kwon Lee. Lee regularly jogs around the reservoir. One day he noticed large black birds completely covering the small island in the lake. The black birds were great cormorants, a type of large water bird, and the trees on the islet were completely covered in the birds' feces. As time passed, Lee made another observation: the lake suffered a severe algal bloom.
Algal blooms deplete oxygen in lakes, produce toxins, and end up killing aquatic life in the lake. This sequence of events got Lee wondering: Did the bird feces cause or contribute to the algal bloom?

The Maji reservoir is an important water source for local farmers who use the water for their crops in the summer. Maintaining water quality is important. About five years ago, the cormorants showed up and now there are 300-500 great cormorants inhabiting the lake and islet. That's a lot of birds and a lot of bird feces, so it's important to understand how the bird feces affects the water. The bird droppings are rich in phosphorus and nitrogen, and when it gets into the water, it adds those nutrients to the water.

Adding nutrients to an existing ecosystem can have a cascading effect. "The feces can influence not only water quality but also whole ecosystems including plants, soil, and other birds," explains Lee.

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