Interannual changes of zooplankton in the Amur Bay
Interannual changes of zooplankton are considered for two parts of the Amur Bay (Peter the Great Bay, Japan Sea) on the base of 650 samples collected in 2007–2011, mostly in summer season. Generally, the zooplankton was more abundant in relatively cool summers, when its total number was in 1.5–2.5 times higher than in warm summers. Cold-water species dominated in the years with cold summer, and warm-water ones — in the years with warm summer. Some species change their abundance in strict dependence on thermal conditions, including several dominant species ( Pseudocalanus newmani, Oithona similis, O. brevicornis ) and several minor ones, as Acartia aff. clausi (definition of Brodsky, 1950), Paracalanus parvus, Calanus glacialis, and some others. However, the dependence on temperature was not evident for some other taxonomic groups. Year-to-year changes of salinity influenced less on the zooplankton composition, though some species were sensitive to salinity: C. glacialis, P. parvus, Evadne nordmanni were more abundant in summers with light freshening of the surface layer, but its low salinity was favorable for A. aff. clausi and O. brevicornis.