New Knowledge on Distribution and Abundance of Toxic Microalgal Species and Related Toxins in the Northwestern Black Sea

Abstract

Numerous potentially toxic plankton species commonly occur in the Black Sea, and phycotoxins have been reported. However, the taxonomy, phycotoxin profiles, and distribution of harmful microalgae in the basin are still understudied. An integrated microscopic (light microscopy) and molecular (18S rRNA gene metabarcoding and qPCR) approach complemented with toxin analysis was applied at 41 stations in the northwestern part of the Black Sea for better taxonomic coverage and toxin profiling in natural populations. The combined dataset included 20 potentially toxic species, some of which (Dinophysis acuminata, Dinophysis acuta, Gonyaulax spinifera, and Karlodinium veneficum) were detected in over 95% of the stations. In parallel, pectenotoxins (PTX-2 as a major toxin) were registered in all samples, and yessotoxins were present at most of the sampling points. PTX-1 and PTX-13, as well as some YTX variants, were recorded for the first time in the basin. A positive correlation was found between the cell abundance of Dinophysis acuta and pectenotoxins, and between Lingulodinium polyedra and Protoceratium reticulatum and yessotoxins. Toxic microalgae and toxin variant abundance and spatial distribution was associated with environmental parameters. Despite the low levels of the identified phycotoxins and their low oral toxicity, chronic toxic exposure could represent an ecosystem and human health hazard.

New tools and recommendations for a better management of harmful algal blooms under the European Marine Strategy Framework Directive

“…Routine monitoring using qPCR or dPCR is already used in the French Atlantic and Mediterranean coasts, the Bay of Biscay, UK, Ireland, the US and New Zealand to provide HAB early warnings (Drouet et al, 2021;Pearson et al, 2021). Metabarcoding methods have also been already widely used to study the dynamics of HAB species and their spatial distribution (Dzhembekova et al, 2022;Gaonkar and Campbell, 2023). Both qPCR/dPCR (Perini et al, 2019) and metabarcoding (Wang et al, 2022) can also be successfully applied to assess the distribution and abundance of toxic dinoflagellate cysts (Perini et al, 2019).…”

Toxic phytoplankton in eutrophic regional seas: an overview

“…According to a recent work by Dzhembekova et al (2022), 27 operational taxonomic units were used and they were assigned to 18 potentially toxic phytoplankton species. The most diversified group in terms of toxic species was the group of dinoflagellates.…”

Official controls for the determination of lipophilic marine biotoxins in mussels farmed along the Adriatic coast of Central Italy

“…There is a global rise in frequency and magnitude of HABs in coastal waters, especially due to the increase of temperatures and anthropogenic sources of nutrients for the phytoplankton community, namely nitrogen and phosphorus, deriving from agricultural run‐offs, inorganic fertilizers, fossil fuels, untreated sewage, and other industrial waste 11 . Potentially toxic microalgae species are widespread globally, but types of poisoning and causative species are generally region specific 12 . DSP is more common in European countries, because of the presence of lipophilic marine biotoxins in bivalve molluscs harvested in the Mediterranean Sea; whereas, PSP is mainly described in Canadian waters, along the Atlantic coasts of the United States (US), as well as in South America and Philippines.…”

“…11 Potentially toxic microalgae species are widespread globally, but types of poisoning and causative species are generally region specific. 12 DSP is more common in European countries, because of the presence of lipophilic marine biotoxins in bivalve molluscs harvested in the Mediterranean Sea; whereas, PSP is mainly described in Canadian waters, along the Atlantic coasts of the United States (US), as well as in South America and Philippines. ASP events affect the Canadian and US coasts of both Atlantic and Pacific Ocean, because of the intense blooms of Pseudo-nitzschia spp.…”