Environmental features and harmful algae in an area of bivalve shellfish production of the Beagle Channel, Argentina

In December 2013 a study was carried out with the objective of knowing the toxic microalgae species present in the area, the different toxins they produce and the environmental factors that condition the distribution of phytoplankton communities and their structure. An alteration in the phytoplankton community structure with respect to the same period of previous years indicated a delay in the early stages of the classic succession. Said delay influenced the annual pattern of harmful species blooms formation in the channel and, consequently, the levels of toxicity of the bivalves normally recorded at that time of the year. The HPLC analysis showed a scarce number of paralytic shellfish toxins that coincided with a very low concentration of toxic cells. In the samples analyzed, the toxins detected were mainly gonyautoxins, with no amnesic shellfish toxin. The results contribute a more detailed knowledge of the toxic profile of bivalves of commercial interest in the area that complements the ongoing monitoring program. The analysis of the environmental parameters showed that the inner sector of A. Brown Bay is an area with restricted circulation that may function as a potential reservoir for the benthic resistance stages of some dinoflagellates, providing an initial inoculum for blooms or local toxicity events formation. The absence of toxic species blooms and the low level of toxicity of the molluscs in the area in that period were associated to unusual climatic conditions registered in the region during the previous months, event that warns about the need to count on a continuous record of the meteorological variables in order to try to predict the occurrence of harmful algae blooms in the channel