Long-term Trends in Pseudo-nitzschia Complex Blooms in the Black Sea - is there a Potential Risk for Ecological and Human Hazards

The potentially toxic genus Pseudo-nitzschia is constantly present in phytoplankton community in the Black Sea often proliferating to bloom concentrations. Production of domoic acid (DA) has been confirmed by local P. calliantha strain and the presence of the neurotoxin has been detected in cultured molluscs and plankton samples from the Bulgarian Black Sea coast. This study aims to provide an overview of the long-term trends of Pseudo-nitzschia blooms in the Black Sea based on inventory of the available information for the period 1959-2019 and assess the relation with key environmental variables. Pseudo-nitzschia species diversity and identification constraints are critically analyzed along with data about the presence of DA in the basin. The results demonstrate that Pseudo-nitzschia spp. may bloom at any time of the year under different environmental regimes. Application of advanced identification techniques, technologically adequate regular monitoring, complemented by toxin analysis is essential to improve our understanding of Pseudo-nitzschia bloom dynamics in order to protect public and ecosystem health hazards.