PATHOGEN SURVEY, GILL Na-K-ATPase ACTIVITY, AND LEUKOCYTE PROFILE OF ADULT DELTA SMELT

摘要

Delta smelt abundance has declined drastically and the species was listed as threatened in 1993. The role of disease in this decline is largely unknown. One hundred and five adult smelt, collected from the lower Sacramento River between January and May 2010, were surveyed for infectious agents, blood leukocyte profile, and gill Na-K-ATPase activity. Few tissue changes or significant parasitic infections were observed in histological specimens and there was a low incidence of bacterial isolations. Asymptomatic Mycobacterium sp. infection was detected in 54% of the samples by PCR; however, this bacterial group was not isolated in culture. Gill Na-K-ATPase activity was lower in the January sample than subsequent month collections. The number of blood granulocytes increased between March and May. Disease did not appear to be an overt influence on the surveyed population in the spring of 2010.