Harmful phytoplankton in the Beagle Channel (South America) as a potential threat to aquaculture activities.

The Beagle Channel is a remote subantarctic environment where mussel aquaculture initiatives have existed since the early 1990s. Here we analyze phytoplankton biomass and composition, and the occurrence of harmful microalgae species and their toxins at three sites during the period 2015-2016. The occurrence of potentially harmful algae was observed throughout the study period, including toxigenic dinoflagellates such as Alexandrium catenella (Group I of the A.

Morphological, molecular, and toxin analysis of field populations of Alexandrium genus from the Argentine Sea.

In the Argentine Sea, blooms of toxigenic dinoflagellates of the Alexandrium tamarense species complex have led to fish and bird mortalities and human deaths as a consequence of paralytic shellfish poisoning (PSP). Yet little is known about the occurrence of other toxigenic species of the genus Alexandrium, or of their toxin composition beyond coastal waters. The distribution of Alexandrium species and related toxins in the Argentine Sea was determined by sampling surface waters on an oceanographic expedition during austral spring from ~39°S to 48°S.

Species occurrence of the potentially toxigenic diatom genus Pseudo-nitzschia and the associated neurotoxin domoic acid in the Argentine Sea.

The marine diatom genus Pseudo-nitzschia, the major known producer of the neurotoxin domoic acid (DA) responsible for the amnesic shellfish poisoning (ASP) syndrome in humans and marine mammals, is globally distributed. The genus presents high species richness in the Argentine Sea and DA has been frequently detected in the last few years in plankton and shellfish samples, but the species identity of the producers remains unclear. In the present work, the distribution and abundance of Pseudo-nitzschia species and DA were determined from samples collected on two oceanographic cruises carried out through the Argentine Sea (∼39-47°S) during summer and spring 2013.

Distribution of Dinophysis species and their association with lipophilic phycotoxins in plankton from the Argentine Sea.

Dinophysis is a cosmopolitan genus of marine dinoflagellates, considered as the major proximal source of diarrheic shellfish toxins and the only producer of pectenotoxins (PTX). From three oceanographic expeditions carried out during autumn, spring and late summer along the Argentine Sea (∼38-56°S), lipophilic phycotoxins were determined by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) in size-fractionated plankton samples. Lipophilic toxin profiles were associated with species composition by microscopic analyses of toxigenic phytoplankton.

THALASSIONEIS SIGNYENSIS (BACILLARIOPHYCEAE) FROM NORTHWEST WEDDELL SEA ICEBERGS, AN EMENDATION OF THE GENERIC DESCRIPTION(1).

We offer an emended description of the genus Thalassioneis based on new observations of the type species, T. signyensis Round, from material sampled in the northwest Weddell Sea. Specimens from algal communities attached to submerged flanks of several icebergs were collected with a remote-operated vehicle (ROV-Phantom DS 2).

Effects of enhanced UV-B on pigment-based phytoplankton biomass and composition of mesocosm-enclosed natural marine communities from three latitudes.

A series of three outdoor mesocosm experiments was undertaken in Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (southern Argentina) to examine the effects of lamp-enhanced UV-B (280-320 nm) on phytoplankton communities isolated from seawater at each site. Detailed pigment composition was used to identify these communities. Each experiment compared three replicated UV-B treatments, consisting of natural sunlight conditions (NUVB), low-level UV-B enhancement corresponding to local 30% ozone depletion (LUVB) and high-level enhancement corresponding to 60% ozone depletion (HUVB).

Ultraviolet-B radiation effects on the structure and function of lower trophic levels of the marine planktonic food web.

The impact of UV-B radiation (UVBR; 280-320 nm) on lower levels of a natural plankton assemblage (bacteria, phytoplankton and microzooplankton) from the St. Lawrence Estuary was studied during 9 days using several immersed outdoor mesocosms. Two exposure treatments were used in triplicate mesocosms: natural UVBR (N treatment, considered as the control treatment) and lamp-enhanced UVBR (H treatment, simulating 60% depletion of the ozone layer).