The hydromedusae fauna of the Northern Adriatic Sea has been subjected
to strong environmental stress and many species have disappeared from
that area. Comparison of all available data shows that only a small n
umber of species are characteristic solely of either northern or south
ern region, and the majority are common to the entire Adriatic Sea. Be
cause of the general pattern of water circulation that shifts gelatino
us plankton from the southern to the northern regions, it is supposed
that the hydromedusan fauna of the Northern Adriatic Sea will be slowl
y repopulated.