Occurrence and Variability of Marine Biotoxins in Mussel (Mytillus Galloprovincialis) and in Plankton Samples from Bulgarian Coast in Spring 2017

Abstract

Shellfish aquaculture has become an increasingly important factor in Bulgarian economy in the recent years. Marine biotoxins, produced by some phytoplankton species, may accumulate in mussels and present an important challenge in commercialization of shellfish. The aim of this study was to determine the occurrence and variability of hydrophilic toxinsparalytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) as well as lipophilic toxinsincluding diarrheic shellfish poisoning (DSP), pectenotoxins (PTXs) and yessotoxins (YTXs) in plankton, wild and farmed mussel samples from the Southern Black Sea coast, an important shellfish farming area in spring 2017. PSP toxins were determined by HPLC with postchromatographic oxidation and fluorescence detection and domoic acid and lipophilic toxins by liquid chromatograph coupled to tandem mass spectrometry. DA and pectenotoxin-2 were detected in plankton, wild and farmed mussel samples. Yessotoxins were detected only in cultivated mussels and no PSP toxins were detected. The occurrence of phycotoxins differed over both space and time. Toxin profile includes prevalent domoic acid, scarce presence of pectenotoxin-2 and yessotoxins in the samples.

Summer profile of lipophilic toxins in shellfish from the Black Sea, Bulgaria

“…Although only 2 samples of the wild mussels were positive for YTX it is obvious that YTXs levels in wild mussels were much lower than the lowest YTX level in cultivated mussels (Table 5). This result was consistent with our previous work [13] where YTX were only detected in farmed mussels. Ndnot detected…”

“…An interesting aspect of the determination of phytoplankton toxicity is the fact that no other marine toxins are detected in the mussel samples although potentially toxic phytoplankton species were registered ( Table 3). This is in agreement with previous work [13] and leads again to the assumption that geographical isolates within the same species have different or no toxin production [43,44].…”

“…In our previous work [13] YTXs were detected in only few samples from the spring of 2017, whereas YTX levels were much lower than reported here. Mean YTX summer levels were approximately 2-3 times higher than the highest in the spring samples.…”

“…Extraction of average 4.02 g hepatopancreas homogenate was performed following the procedure described in Peteva et al [13].…”

“…No official medical statistics exist on human intoxications caused by HAB toxins. However, recent research on phytoplankton and mussel samples from the Black Sea showed the presence of hydrophilic toxinsdomoic acid [12,13] and paralytic shellfish toxins [14,15] and lipophilic toxinsyessotoxins and pectenotoxins [13,16] in the Black Sea. But still data on occurrence of lipophilic toxins along the Bulgarian coast remain insufficient [17].…”