Abstract

The unexpected Alexandrium catenella bloom in the Pacific Ocean (43°S-39°S) in April-May 2016 caused Paralytic Shellfish Poison (PSP), stranded bivalve mollusks (e.g. Mesodesma donacium) and mortality of birds and marine mammals, besides a strong effect to the social and economic system. The case of four pet dogs, who died after licking kelp fronds (Macrocystis pyrifera; Durvillaea antarctica) at Mansa Bay (40°34’52.3”S; 73°44’13.6”W), region of Los Lagos, is presented. A veterinarian suggested an intoxication by PSP. No samples of poisoned dogs but were collected stranded kelp samples. The frond and stipe presented its surface covered by a barnacle (Lepas australis), which would have been eaten by the dogs. Were performed a HPLC analysis to search PSP in barnacles and wash water of kelp+barnacles and mouse bioassay for kelp wash water. The barnacles had a toxicity between 107-178 μg STX eq.100 g-1, while the wash water of the kelp+barnacle had a lower concentration (0.5 μg STX eq.100 g-1). In the first case, 95% were gonyaulatoxins (GTX2-3) and the remaining 5%, saxitoxin (STX), while in the wash water 53% were GTX2-3 and 48% STX. Kelp wash water had 118 μg STX eq.100 g-1. The adherence of A. catenella vegetative cells to the barnacle’s surface or kelp’s mucous might explain the PSP in the wash water, but no A. catenella cells or cysts in the wash water were observed. The results suggest that both the licking on stranded kelp or kelp+barnacles and the ingestion of toxic barnacles might explain the dogs’ death.