Intensity and extent of harmful microalgae increase

[Chile] The microalgae Alexandrium catenella, which caused the red tide phenomenon that affects the region of Los Lagos, may still be in their growth phase, so it is expected to increase both in intensity and geographical distribution.

This was reported by the Emergency Scientific Advisory Committee which met yesterday to update the information regarding the concentration of the paralytic shellfish poisoning and, at the same time, to estimate the resource detoxification time.

According to the first report issued by the advisory body, formed by Mayor Leonardo de la Prida, especially to analyze the phenomenon, this is the first time it the microalgae bloom causing the shellfish paralytic toxin has been detected at this intensity along the exposed coast of the Region of Los Lagos. This situation contrasts with the previous records of blooms of this species, which had been detected only in the fjords and channels of the southern zone.

The Committee also confirmed that the progress and intensity of the A. catenella bloom is unprecedented towards the north of Chacao Channel and the concentrations of the poisonous shellfish paralytic recorded in the sectors of Carelmapu, Maullin, Rio Negro and Bahia Mansa, reported the Undersecretariat of Fisheries and Aquaculture (SUBPESCA).

According to the report, considering the microalgae life cycle and oceanographic spread mechanisms -. that is to say, the currents –, it is expected that it continues extending and expanding its spatial distribution along the coast.

The document adds that while the existing information is scarce, its presence, intensity and extent could be attributed to the prevailing climatic conditions at local and global scale, influencing the oceanographic characteristics and promoting the growth of this toxic microalgae. The presence of El Niño phenomenon, which has shown superior intensity to the events reported during the last 50 years, is added and would be further enhancing this phenomenon.

Experts also noted that the resource detoxification period will depend on the contamination level present, which may be extended from a month, in the case of the species that have low levels of toxic concentration — to one year, as is the case of the resources that have been exposed to high concentrations of toxin.

In addition to accumulating toxins, these organisms may also be affected by high concentrations of toxins, such as foot “numbness” of the clam, causing them to close, be exposed to waves and get stuck on the bank, as it happened recently in Cucao and Mar Brava, Chiloe Island, the Committee noted.

The paralytic shellfish poisoning has been detected in clams, razor clams, mussels, giant mussels, culengue, tumbao, conchs, barnacles, piure clam and bull kelp. For that reason, the health authority recommends not to consume these products — raw or cooked.

It must be recalled that last Friday the President of the Republic, Michelle Bachelet, declared the coast of the Region of Los Lagos is a disaster area and announced a series of measures to aid the sectors affected by the red tide.

 

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