The neustonic fauna in coastal waters of the northeast Pacific: abundance, distribution, and utilization by juvenile salmonids

The surface-layer zone, occupying the upper 20 cm of the water column, represents a unique oceanic environment. A diverse assemblage of organisms occupies this zone, either in an obligate or facultative manner (Zaitsev 1970, Hempel and Weikert 1972, Cheng 1975, Peres 1982). Certain animals show morphological or biochemical adaptations to this environment and are generally found in this layer throughout their life cycles. More often, however, species may be found near the surface for only a limited part of their life cycle, as in the case of diel migrants (Zaitsev 1970). These organisms have been collectively referred to as pleuston if they are found at the air-sea interface and neuston if they reside immediately below this interface (Cheng 1975)