To rule out the possibility that the unsuccessful search was due to their method, the researchers also used the same approach to look for evidence of the dispersal of aquatic invertebrates. The result shows that no in-depth scientific studies exist to prove that water birds disperse fish eggs. To objectively measure the lack of evidence, the Basel research team conducted a systematic literature review.
The theory is thus that the fish eggs stick to water birds’ feathers or feet the birds then fly from one body of water to the next, where the fish hatch from their eggs.Ī study carried out by environmental scientists from the University of Basel has now shown that although the research community considers this to be a proven theory, no studies have been published to confirm it. This question was already addressed by some of the leading natural scientists of the 19th century such as Charles Darwin, Alfred Russel Wallace and Charles Lyell, who all came to the same conclusion – water birds must be responsible for fish dispersal.Īnd they had a plausible explanation for this: fish eggs of some species are sticky and can survive for some time out of water.
So how do fish reach lakes and ponds that are not connected to other bodies of water? Yet in most of these lakes, there are fish.
Many of these lakes are found in remote, often mountainous areas with no inflow and outflow. Small lakes with a surface area of less than 100 m 2 represent the majority of global freshwater ecosystems.
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