Document Type



Virginia Institute of Marine Science

Publication Date



Special papers in marine science; No. 1.


A survey was made in southern Chesapeake Bay and its tributaries from April 1965 through March 1968 to determine the species of hydrozoans present, their seasonality and reproductive periodicities. This report discusses 43 hydroid and 27 medusa species known from the study area, of which 23 hydroids and 11 medusae have not previously been found in Chesapeake Bay. Clytia paulensis and the hydroid of Moerisia lyonsi have not been reported before in North American waters, and the hydroid of Amphinema dinema is recorded for the first time from the western Atlantic. The present records extend the northern range of one hydroid (Clytia kincaidi) and two medusae (Podocoryne minima and Phialucium carolinae) and the southern range of three hydroids (Ectopleura dumortieri, Obelia prolifer and Sarsia tubulosa) to Chesapeake Bay. Both hydroids and hydromedusae show greater zoogeographic affinity with the southern Carolinian Province than with the Acadian Province. The life histories of Bougainvillia rugosa and Lovenella Gracilis are studied and described. The genus Calyptospadix Clarke, 1882 is placed in synonymy with Garveia Wright, 1859. Three other hydroids, "Campanopsis" sp., "Campanulina" sp. 1 and "Campanulina" sp. 2, are not described in the literature for this coast and require further life history studies to elucidate their generic and specific identity. Hydroids and hydromedusae were characteristically seasonal in occurrence due to the annual water temperature range, varying from about 2 C in winter to 28 C in summer. Of 23 hydroids whose seasonality was studied in detail, 16 were "summer" species and seven were "winter" species, The seasonal occurrence of the hydromedusae was typically less prolonged, with a maximum diversity in late summer and early autumn, and a minimum diversity in winter.



Hydrozoa -- Chesapeake Bay (Md. and Va.) Hydromedusae -- Chesapeake Bay (Md. and Va.)

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