Sea otters are known as a keystone species, filling such an important niche in ocean communities that without them, entire ecosystems can collapse. Scientists are finding, however, that sea otters can have even farther-reaching effects that extend to terrestrial communities and alter the behavior of another top predator: the bald eagle.

Researchers of the Helmholtz Center for Environmental Research have developed two new methods, in order to be able to better estimate the numbers of European Otters (Lutra lutra) and their effects on the fish farming industry.

Ecologists have long observed that when food becomes scarce, animal populations exploit a wider range of food sources. So scientists studying southern sea otters at different sites in California's coastal waters were not surprised to find that the dietary diversity of the population is higher where food is limited.