Induction of toxin production in dinoflagellates: the grazer makes a difference

• The dinoflagellate Alexandrium minutum has previously been shown to produce paralytic shellfish toxins (PST) in response to waterborne cues from the copepod Acartia tonsa. In order to investigate if grazer-induced toxin production is a general or grazer-specific response of A. minutum to calanoid copepods, we exposed two strains of A. minutum to waterborne cues from three other species of calanoid copepods, Acartia clausi, Centropages typicus and Pseudocalanus sp. Both A. minutum strains responded to waterborne cues from Centropages and Acartia with significantly increased cell-specific toxicity. Waterborne cues from Centropages caused the strongest response in the A. minutum cells, with 5 to > 20 times higher toxin concentrations compared to controls. In contrast, neither of the A. minutum strains responded with significantly increased toxicity to waterborne cues from Pseudocalanus. The absolute increase in PST content was proportional to the intrinsic toxicity of the different A. minutum strains that were used. The results show that grazer-induced PST production is a grazer-specific response in A. minutum, and its potential ecological importance will thus depend on the composition of the zooplankton community, as well as the intrinsic toxin-producing properties of the A. minutum population.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Keyword

acartia tonsa

alexandrium minutum

centropages typicus

inducible defense

paralytic shellfish toxin

pseudocalanus sp

phaeocystis-globosa prymnesiophyceae

alexandrium-minutum

colony formation

zooplankton

prey

resistance

defenses

copepods

cues

phytoplankton

Publication and Content Type

ref (subject category)

art (subject category)