The classical models of production and plankton community dynamics in coastal waters include an important role for benthic-pelagic coupling in the form of biogcochemical cycling (the turnover of nutrients in the form of either living matter or its decomposed constituents). We think, however, that biogeochemical explanations of ecosystem functioning underrepresent the actual complexity of the studied phenomena. We suggest that models will be more complete if they incorporate life-cycle patterns of planktonic and benthic organisms. The inclusion of such biological information into an ecological context will enhance the understanding of ecological patterns of global importance. What we presently know provides compelling evidence that new research directions, ranging from sedimentology to systematics and from physiology to molecular biology, are needed.

Seabed cores to a sediment depth of 24 cm were obtained by divers from an anoxic basin in the Pettaquamscutt estuary. The cores were processed to determine the age, viability, and vertical distribution of zooplankton resting eggs in the bottom sediments. Zooplankton eggs were found throughout the upper 24 cm. Copepod nauplii emerged from sediments as deep as 22 cm that were incubated in the laboratory. Based on 210Pb analyses of the sediments, we calculated that the viable eggs ranged in age from <1 yr in the surface layers of the seabed to >40 yr in the deepest portions. These data provide conclusive evidence for the existence of an egg bank.

The occurrence of a resting egg phase in the life cycle of marine and freshwater planktonic copepods is well documented and receiving increasing attention by investigators. The species generally occur in coastal marine waters, freshwater ponds and lakes in areas that undergo strong seasonal fluctuations, though examples have been reported for tropical and sub-tropical areas not subject to such extreme fluctuations. Typically such species disappear from the water column for portions of the year, but remain in the region as benthic resting eggs. Studies to date have focused on the conditions that promote the occurrence of resting eggs, the factors that affect their survival and hatching from sediments, the existence of egg banks in sediments, and the impact of resting eggs on plankton community structure. Benthic resting eggs of copepods include diapause eggs as well as subitaneous (non-diapause) eggs that are quiescent due to conditions in the sediments. As with other groups of organisms the resting egg phase is viewed as being critical for the perpetuation of species year after year, especially those that disappear from the water column for portions of the year. Some data indicate that eggs can survive for many years in sediments which would expand their influence to evolutionary time scales. This paper summarizes our understanding of embryonic dormancy in marine copepods.

During the last 10 yr it has been shown that the eggs of many zooplankters (e.g. copepods,cladocerans, tintinnids) occur in bottom sediments of coastal regions. Accumulations of these eggs on the sea-bottom may represent an important source for the recruitment of individuals into the plankton. We examined vertical distribution and viability of copepod eggs at several locations in Buzzards Bay, Massachusetts USA. Cylindrical cores were obtained by divers. In the laboratory each core was divided at 1.0 cm intervals to a maximum depth of 10.0 cm. From each layer 2 subcores were taken. One was suspended in seawater and incubated for several days at 19 OC. Hatched nauplii were collected, counted, and reared for identification. Viable eggs (evidenced by appearance of nauplii) were found at all depths in the sediment. The greatest densities (106 to 107 m-') often occurred several cm below !he water-sediment interface. Egg abundance was not significantly correlated with sediment grain size. The other subcore was sonified so that the eggs of Labidocera aestiva could be removed, counted, and incubated (to determine viability). Laboratory feeding experiments indicate that diapause and subitaneous eggs of L. aestiva remain viable after being consumed by either Capitella sp. 1 or Streblospio benedicti which are common benthic consumers in regions where eggs occur. The relative importance and influence of physical factors (waves, tidal and wind-driven currents) and biological factors (feeding and bioturbating activities of benthic animals) on the distribution, abundance, and viability of eggs on the sea-bottom is discussed.

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