Lack of allelopathic effects of the domoic acid-producing marine diatom Pseudo-nitzschia multiseries

Abstract

Many Pseudo-nitzschia species produce the toxin domoic acid, which accumulates in the food web during blooms, sometimes causing amnesic shellfish poisoning (ASP) in higher trophic levels, including humans. In addition, Pseudo-nitzschia species have been reported to form longlasting monospecific blooms, and a possible explanation for this could be allelopathic effects of the toxin, since domoic acid has been detected in high amounts in the surrounding medium in stationary growth phase. We therefore examined the potential allelopathic effects of P. multiseries and its toxin domoic acid. In mixed-batch culture studies of domoic acid-producing P. multiseries and the algal test species Chrysochromulina ericina, Heterocapsa triquetra, Eutreptiella gymnastica and Rhodomonas marina, no allelopathic effects of P. multiseries were found. Different growth results using 2 different strains of P. multiseries grown with C. ericina were explained by minor differences in pH. Bioassays testing the effect of domoic acid itself on 9 different phytoplankton species, namely C. ericina, E. gymnastica, Karenia mikimotoi, H. triquetra, Heterosigma akashiwo, Prorocentrum minimum, P. micans, Pyramimonas propulsa and R. marina confirmed a lack of allelopathic effects of the toxin. This lack of allelopathic effect of the shellfish-poisoning toxin domoic acid seems to correspond with the results of phytoplankton species causing DSP (diarrheic shellfish poisoning) and PSP (paralytic shellfish poisoning), where it appears that these shellfish-poisoning toxins do not cause allelopathic effects either.

Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health

“…Mixed culture experiments, however, showed no allelopathic effects of toxic P. multiseries on Chrysochromulina ericina, Heterocapsa triquetra, Eutreptiella gymnastica or Rhodomonas marina (Lundholm et al, 2005b). Similarly, additions of DA alone to the water had no allelopathic effects on 11 different phytoplankton organisms (Windust, 1992;Lundholm et al, 2005b). Thus, there is still no evidence that allelopathic effects are likely to contribute to the formation of long-lasting Pseudo-nitzschia blooms, or serve as an explanation for the evolution of DA production.…”

“…It is therefore reasonable to speculate that this toxin could have an allelopathic effect. Mixed culture experiments, however, showed no allelopathic effects of toxic P. multiseries on Chrysochromulina ericina, Heterocapsa triquetra, Eutreptiella gymnastica or Rhodomonas marina (Lundholm et al, 2005b). Similarly, additions of DA alone to the water had no allelopathic effects on 11 different phytoplankton organisms (Windust, 1992;Lundholm et al, 2005b).…”

Diatom blooms and primary production in a channel ecosystem of central Patagonia

“…In a highly mixed and disturbed environment, enhanced competitive ability for resources is probably the main factor favouring the dominance of certain species. However it is interesting to note that field and laboratory experiments have shown that Skeletonema and Pseudo-nitzschia species can release allelophatic compounds (e.g., Lundholm et al, 2005;Yamasaki et al, 2010;Xu et al, 2015) that could also be a factor in promoting mono-specific blooms in the channel.…”

Induction of domoic acid production in the toxic diatom Pseudo-nitzschia seriata by calanoid copepods

“…Lundholm et al, 2004), and trace metal limitation or toxicity (Maldonado et al, 2002). Evidence of allelopathic effects of DA, however, has not been found (Lundholm et al, 2005). DA is an amino acid and thus nitrogen is needed for its synthesis.…”