Ecological niche partitioning of the invasive dinoflagellate Prorocentrum minimum and its native congeners in the Baltic Sea

• Published in: Harmful algae 2016-11, Vol.59, p.100-111
• Main Authors: Telesh, Irena V., Schubert, Hendrik, Skarlato, Sergei O.
• Format: Article
• Language: English
• Subjects: Algal blooms; Baltic Sea; Biological invasions; Dinoflagellates; Ecological niche; Prorocentrum minimum
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2016.09.006

•Prorocentrum minimum shows long delay of first bloom after invading the Baltic Sea.•High Baltic microbial diversity hampered fast bloom formation by P. minimum.•The generalist P. minimum shares ecological niche with 4 congeners in SW Baltic Sea.•Major blooms of P. minimum occur at salinities 7.9±1.8 and temperature 20.8±3.7°C.•Ecological niche of P. minimum in the Baltic Sea is narrower than in Chesapeake Bay. This study analyses three decades of the peculiar bloom-formation history of the potentially toxic invasive planktonic dinoflagellates Prorocentrum minimum (Pavillard) Schiller in the SW Baltic Sea. We tested a research hypothesis that the unexpectedly long delay (nearly two decades) in population development of P. minimum prior to its first bloom was caused by competition with one or several closely related native dinoflagellate species due to ecological niche partitioning which hampered the spread and bloom-forming potential of the invader. We applied the ecological niche concept to a large, long-term phytoplankton database and analysed the invasion history and population dynamics of P. minimum in the SW Baltic Sea coastal waters using the data on phytoplankton composition, abundance and biomass. The ecological niche dimensions of P. minimum and its congener P. balticum were identified as the optimum environmental conditions for the species during the bloom events based on water temperature, salinity, pH, concentration of nutrients (PO43−; total phosphorus, TP; total nitrogen, TN; SiO44−), TN/TP-ratio and habitat type. The data on spatial distribution and ecological niche dimensions of P. minimum have contributed to the development of the “protistan species maximum concept”. High microplankton diversity at critical salinities in the Baltic Sea may be considered as a possible reason for the significant niche overlap and strong competitive interactions among congeners leading to prolonged delay in population growth of P. minimum preceding its first bloom in the highly variable brackishwater environment.