Eutrophication trends in the coastal region of the Great Tokyo area based on long-term trends of Secchi depth.

Background: The coastal ocean's environment has changed owing to human activity, with eutrophication becoming a global concern. However, oligotrophication occurs locally and decreases fish production. Historically, the Secchi depth has been used as an index of primary productivity.

Multiple preferred escape trajectories are explained by a geometric model incorporating prey's turn and predator attack endpoint.

The escape trajectory (ET) of prey - measured as the angle relative to the predator's approach path - plays a major role in avoiding predation. Previous geometric models predict a single ET; however, many species show highly variable ETs with multiple preferred directions. Although such a high ET variability may confer unpredictability to avoid predation, the reasons why animals prefer specific multiple ETs remain unclear.