Vulnerability of marine fish larvae to the toxic dinoflagellate Protogonyaulax tamarensis

Abstract

Fish larvae and early postlarvae proved highly vulnerable to the toxins of the dinoflagellate Protoyonyaulax tamarensis. Capelin Mallotus villosus and Atlantic herring Clupea harengus harengus larvae from the St. Lawrence Estuary, Canada, were exposed to variable concentrations of a toxic strain (treatment) and a non-toxic strain (control) of P. tamarensis. When exposed directly to the dinoflagellate, mortality due to the toxin (treatment minus control) was strongly correlated with the percentage of larvae that ingested cells. At cell concentrations (1500 cells ml-') that compared with local bloom densities, mortality reached 92 and 77 % d-' in capelin and herring, respectively. The mortality of herring postlarvae fed toxic microzooplankton ranged from 17 to 36 % d-' Age-and dosedependent variations in vulnerability were linked to early ontogenetic changes in the feeding efficiency and food selectivity of both species. We conclude that the present proliferation of toxic dinoflagellates in coastal waters could jeopardize the early survival of fish and recruitment to fisher~es by narrowing the spatiotemporal window within which spawning leads to successful reproduction.

Patterns of paralytic shellfish toxicity in the St. Lawrence region in relationship with the abundance and distribution of <i>Alexandrium tamarense</i>

“…Analysis of the Alexandrium cells and cysts showed that the indigenous population contained high concentrations of PSP toxins (Cembella et al, 1988b). Tentative hypotheses were proposed concerning the relationship between the distribution of Alexandrium and the environmental variables, as well as the possible impact of the organism on the entire ecosystem (Gosselin et al, 1989;Desbiens et al, 1990;Robineau et al, 1991;Levasseur et al, 1994;Desbiens and Cembella 1995;Turriff et al, 1995). In 1984, the Department of Fisheries and Oceans of Canada, Inspection Branch, Quebec, assumed responsibility for shellfish monitoring and began to provide more precise information about the temporal and spatial distribution of toxicity along the entire coast.…”

What is a bloom? A commentary

“…At yet another level, ingestion of only 6-11 cells of toxic Alexandrium tamarense was lethal to first-feeding sea bream (Pagrus major) larvae (White ct al. 1989), and only one cell of a more toxic strain was lethal to capelin (Mallotus villolus) and herring (Clupea harengus harengus) larvae (Gosselin et 'al. 1989).…”

Effects of variations of environmental factors and algal bloom on fish larvae in Southern central Vietnam

“…There is either a direct action of the algae on the fish themselves, especially on sensitive organs such as the gills, liver, and tissue of the nervous system, or indirect impacts on food web that lead to mortality of predators which consume herbivores that fed on blooms. Larvae and early post larvae were highly vulnerable when exposed directly to the toxin produced by the dinoflagellate Protogonyaulax tamarensis (Gosselin et al, 1989). The impact of extracted toxin of Alexandrium minutum on oxygen consumption rates or critical oxygen demand of milkfish (Chanos chanos) fingerlings has also been reported (Chen and Chou, 2001).…”