Responses of a Mediterranean soft bottom community to short-term (1993-1996) hydrological changes in the Rhone river.

摘要: The polychaete fauna of muddy bottoms off the Rhone delta (NW Mediterranean) was seasonally sampled at two sites 70 m depth, from 1993 to 1996. During this period, five severe flood events occurred. A clustering analysis (distance coefficient Whittaker) and three way fixed factor ANOVAs (site x season year) showed strong year-to-year changes in species density community structure, that masked seasonal variations. Total increased by a 3 most significantly following first flooding event. Changes structure were due successive dominance few species. opportunistic species, such as Cossura sp., Mediomastus sp. Polycirrus exhibited peaks 1-3 months after flood. These followed drastic decline. For with long life span, Sternaspis scutata, slower but continuous increase observed which maintained for several months. fluctuations these good correlation river flow time lags 1-2 years. successional dynamics are explained according geographical origin floods biology feeding ecology