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Document Type

Book Chapter


Virginia Institute of Marine Science

Publication Date



Project Coordinator, Jackson Davis (VIMS) | Volume Coordinator, Beverly Laird (VIMS)

Book Title

The effects of Tropical Storm Agnes on the Chesapeake Bay Estuarine System


Chesapeake Research Consortium


Chesapeake Research Consortium publication ; no. 54


Tropical Storm Agnes caused major changes in the macroinvertebrate assemblages of both epifauna and infauna in eelgrass, Zostera marina, beds. Species abundance and density of infauna declined by one-third to one-half of values found prior to Agnes. Typical members of the infaunal community such as the amphipods, Ampelisca spp. and Lysianassa alba, the polychaetes Sabella microphthalma and Exogone dispar, ostracods and gastropods were either absent or rare following Agnes. Epifaunal density was much higher than that recorded before Agnes but the number of species was reduced. This high density was attributed to several species, e.g. Molgula manhattensis, which appeared to occupy space left open by the absence of typical members of this community, e.g. Paracereceis caudata and Bittium varium. The abnormally low salinities following Agnes affected various species in different ways. Some species were totally eliminated, severely reduced in abundance or, in a few euryhaline species, not affected at all. In some populations it appeared that adults survived but juveniles suffered high mortalities. Recovery and reestablishment by many species will be complicated by the disappearance of eelgrass in some portions of the Bay.

The effect of Tropical Storm Agnes on the benthic fauna of eelgrass, Zostera marina, in the lower Chesapeake Bay