Fish Dispersal

Small lakes with a surface area of less than 100? represent the majority of global freshwater ecosystems. Many of these lakes are found in [blank] , often mountainous areas with no inflow and outflow. Yet in most of these lakes, there are fish. So how do fish reach lakes and ponds that are not connected to other bodies of water? 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 [blank] . And they had a plausible explanation for this: fish eggs of some species are sticky and can survive for some time out of water. The theory is thus that the fish eggs stick to water birds' [blank] or feet; the birds then fly from one body of water to the next, where the fish [blank] from their eggs.