Characterization and comparison of toxin‐producing isolates of Dinophysis acuminata from New England and Canada

Abstract

Following the identification of the first toxic isolate of Dinophysis acuminata from the northwestern Atlantic, we conducted detailed investigations into the morphology, phylogeny, physiology, and toxigenicity of three isolates from three sites within the northeastern U.S./Canada region: Eel Pond and Martha’s Vineyard, Massachusetts, and the Bay of Fundy. Another isolate, collected from the Gulf of Mexico, was grown under the same light, temperature, and prey conditions for comparison. Despite observed phenotypic heterogeneity, morphometrics and molecular evidence classified the three northwestern Atlantic isolates as Dinophysis acuminata Claparède & Lachmann, whereas the isolate from the Gulf of Mexico was morphologically identified as D. cf. ovum. Physiological and toxin analyses supported these classifications, with the three northwestern Atlantic isolates being more similar to each other with respect to growth rate, toxin profile, and diarrhetic shellfish poisoning (DSP) toxin content (okadaic acid + dinophysistoxin 1/cell) than they were to the isolate from the Gulf of Mexico, which had toxin profiles similar to those published for D. cf. ovum F. Schütt. The DSP toxin content, 0.01 – 1.8 pg okadaic acid (OA) + dinophysistoxin (DTX1) · cell−1, of the three northwestern Atlantic isolates was low relative to other D. acuminata strains from elsewhere in the world, consistent with the relative scarcity of shellfish harvesting closures due to DSP toxins in the northeastern U.S. and Canada. If this pattern is repeated with analyses of more geographically and temporally dispersed isolates from the region, it would appear that the risk of significant DSP toxin outbreaks in the northwestern Atlantic is low to moderate. Finally, the morphological, physiological, and toxicological variability within D. acuminata may reflect spatial (and/or temporal) population structure, and suggests that sub-specific resolution may be helpful in characterizing bloom dynamics and predicting toxicity.

Characterization of Dinophysis spp. (Dinophyceae, Dinophysiales) from the mid‐Atlantic region of the United States1

“…The ability to use the metrics outlined by Tong et al. () to speciate these Dinophysis was consistent with statistically significant differences in morphometric characteristics. Univariate ANOVA on morphometric data, with post hoc REGWF multiple comparisons tests, indicated that species within the Dinophysis acuminata ‐complex could be separated from each other using a series of morphometrics (Fig.…”

“…In all, 322 individually picked Dinophysis cells were examined using the six metrics outlined in Tong et al. (). From all samples analyzed, five primary morphospecies were identified, measured, and photographed from 24 preserved water samples, a clonal culture of D. acuminata (DADE01) established from Torquay Canal, Delaware, and a clonal culture of D. ovum (DoSS 3195) established from Freeport, Texas.…”

“…Cell measurements followed the morphometric parameters described in Tong et al. (), which included cell body length, cell body depth, left sulcal list length (LSL), anterior cingular list width (ACL), posterior cingular list width (PCL), and total length to depth ratio (L:D). Morphometric data were analyzed using a univariate ANOVA to identify significant differences between Dinophysis morphospecies with post hoc REGWF multiple comparison tests at an Alpha of 0.05 using IBM SPSS v. 20.…”

Potentieel toxisch fytoplankton in productiegebieden van tweekleppige weekdieren : evaluatie van het Nederlandse monitoringsprogramma met voorstellen voor een alternatieve aanpak

“…Het toxine gehalte en de toxine samenstelling van verschillende fytoplanktonstammen kan sterk verschillen. Zo is het bijvoorbeeld van sommige cyanobacteriën en de dinoflaggelaat D. acuminata bekend dat bepaalde stammen niet in staat zijn toxines te produceren, terwijl andere stammen van dezelfde soort dat wel kunnen [87,[116][117][118][119].…”

“…• Het toxine gehalte in de cel binnen een stam kan verschillen als gevolg van veranderende groeiomstandigheden en groeisnelheden [87,[116][117][118].…”