Results of a Kruskal-Wallis nonparametric one factor ANOVA for differences in CTX toxicity among <i>Gambierdiscus</i> and <i>Fukuyoa</i> species.

<p><i>Gambierdiscus excentricus</i> and <i>G</i>. <i>silvae</i> were excluded from the analysis because only a single clone was examined. Abbreviations: n = sample size, M = median toxicity (fg CTX3C eq. cell^-1), <i>H</i> = Kruskal-Wallis test statistic, <i>df</i> = degrees of freedom. Brackets denote result of the Dunn’s follow up test. The statistic is designed to estimate median toxicities to determine if the species partitioned into distinct groups.</p

Representative plots showing the long-term steady state growth of the <i>Gambierdiscus</i> and <i>Fukuyoa</i> isolates achieved in this study.

<p>Exponential growth was achieved by acclimating cells to optimal temperature, light and nutrient conditions and maintained in exponential growth phase by periodic dilution with nutrient rich media.</p

The species, strain designations, isolate locations, replicate growth rates and toxicities of the <i>Gambierdiscus</i> and <i>Fukuyoa</i> strains examined in this study.

<p>The citations in the species column indicate where the species was described. The reference(s) under the strain designation indicate other publications where the strain has been studied. Many of the strains analyzed for CTX-like activity in this study were also assayed for maitotoxicity in separate investigations [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185776#pone.0185776.ref032" target="_blank">32</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0185776#pone.0185776.ref033" target="_blank">33</a>]. The strain growth rates (± standard deviation) were determined from triplicate, independent cultures started for each isolate. Mean species growth rates and average toxicities were determined by averaging all replicate culture data for a given species. Toxicity was normalized both as femtograms (fg) CTX3C equivalents [eq.] cell^-1 and per biovolume attograms (ag) CTX3C eq. μm^-3. Numbers in parentheses in the data cells of the last three columns = coefficient of variation. Correlation coefficients (R²) for the time versus cell number relationships used to the calculate growth rates for each of the cultures exceeded 0.98.</p

Toxin production rates.

<p>This figure shows the estimated toxin production (fg CTX3C eq. cell^-1 d^-1) rate for each species.</p