The zrmanja river estuary ( eastern adriatic sea )

The spatial and temporal distributiQl1 of the diatom genus I'se"do-"il;;.schia was investigated in tile small, highly stratified Znnanja River estual)' (eastern Adriatic Sea) from 1998 to 2004. During this period. I'u'''/o_nil;;.schi'' spp. IlI<)stly dominated the phytoplankton assemblages (al>undance d<»e to 1.3 ~ 10" cells L-', appean:(! in 51% Qf the samples). The maximum abundance of I'se",;h-"il;;.schia spp. was during mid_winter (FebnJary 1999), when it contributed up \Q 85% of the tOlal dialOm abundance. Pseuoo_nilZSchi" bloom was significantly correlated with phosphorous concentnllion and temperamre. whe",as there "'as no significant ool1dation with tOlal ioorganie nitrogen, silicate and salinity. The "el)' broad range of environmental factors o,'er which I'seudo-nil;;.sehio spp. were obsen:ed suggestS tllere was more than one I'se"da-"il:schia species in the diatom assemblage. Morphological analysis has shown that the dominating Pse"do-nilZSehio species com:sponded to PseuckJni';;.scho'o collitmlho. Two other spe<:ies were eneounte",d; Ql1e identified as Pseudo-nil:schia heimii. while other has yet to be identified. This smdy was the first \Q find I'. heimi; in the Adriatic Sea and the first to record the presence ofa potentially \Qxic diatom P. ca/liomhu in an Adriatic estuary.