American Scientist

A hydraulic jump can be spectacular. When, at the foot of a waterfall or below a boulder, you see a standing wave that rears up as a foaming breaker with a tumbling, undulating crest that seems forever poised to rush upstream without actually doing so, you are looking at a hydraulic jump . . . . The current within the standing wave [makes] . . . a good takeoff point for salmon . . . on their upstream migration to their spawning beds.

Fresh Water
E. E. Pielou
University of Chicago Press, $24

The discharge of nutrients and pollutants into the sea in some coastal areas has led to the disappearance or near-disappearance of some species, an increasing frequency of phytoplankton blooms, and the growth of so-called dead zones where diminished oxygen supplies prevent the grown of marine life. The anoxic dead zone in the Gulf of Mexico lasts approximately eight months a year and can extend over 9,000 square kilometers.

The Ocean, Our Future
Mário Soares
Chair, Independent World Commision on the Oceans
Cambridge University Press, $22.95, paper

Very little is known about this species, Phrynichthys wedli, a small anglerfish inhabiting the waters off the continental shelf on both sides of the Atlantic. No male specimens have ever been found. This juvenile was caught in the Caribbean by the slurp gun of a research submarine at 1,000 meters.

Encyclopedia of Fishes
John R. Paxton and William N. Eschmeyer, consulting eds.
Academic Press, $34.95