Bellis, V.Odum, H.T., B.J. Copeland, and E.A. McMahanCoastal ecological systems of the United States. Volume II.2010-02-152010-02-151974http://hdl.handle.net/1969.3/18860pgs. 358-396This article presents a discussion of the middle estuary. This part of an estuary is difficult to define. An arbitrary working definition has been accepted by many persons in the field: the characteristics of the middle estuary correspond most closely with portions of the estuary having average salinities between 5-18 ppt. The middle estuary is important because the greatest area of many North American estuaries of this type, and it is this coast estuaries seem to have significant middle salinity regions.estuariesplanktonsalinity gradientsmarine fisheriesfood websorganic matterbiomassestuarine ecologyestuariesestuarine oceanographyChapter