Table 1.
Species of marine phytoplankton used for exposure experiments to test their toxicity on fish cells RTgill-W1, and production of superoxide radicals.
The nontoxic species Tetraselmis suecica was used as a negative control. Two strains of the raphidophyte Chattonella marina were used.
Fig 1.
Viability of gill cells RTgill-W1 after a 2-hr exposure to seven species of ichthyotoxic microalgae and one nontoxic.
A) Whole algal cells, B) Lysed cells, and C) Correlation between algal biovolume and gill cell viability (blank circles are for lysed algal cells and black circles for whole cells. Trend line and equation correspond to a linear regression). Error bars indicate standard deviations, and letters on top of columns represent significant differences among treatments (whole and lysed cells of three concentrations) within each species. Chattonella marina includes the two strains CMPL01 (Australian) and N118 (Japanese). Tetraselmis suecica was used as a nontoxic control.
Fig 2.
Production of superoxide radicals O2- by algal species under two conditions (whole and lysed cells) at three concentrations each.
Error bars represent standard deviations of production rates (n = 3), and letters on top of columns indicate significant differences among all treatments across species with production rates higher than 0.59 pmol cell-1 hr-1. ANOVA, F0.05;53,108 = 441.
Fig 3.
Activity of the enzyme superoxide dismutase from gill cells exposed to toxic algae (except for TSCS187).
SOD activity in control cells exposed only to GSe medium was 8.9% inhibition, and activity of gill cells with the letter “a” was not significantly different to control cells. Comparisons were performed among all treatments across species. ANOVA, F0.05;54,55 = 70.7.
Fig 4.
Relationship between (A) superoxide production by algae and SOD activity in gill cells, (B) superoxide production by algae and gill cell viability, and (C) gill cell SOD activity and viability after exposure to algae.
Red symbols are for Chattonella marina, and blue symbols for Alexandrium catenella. Trend lines and equations of the adjustment (exponential regression) are shown for all data (black line and top equation) and data from C. marina and A. catenella (red interrupted line and bottom equation in B and C).
Fig 5.
Release of the enzyme lactate dehydrogenase by gill cells (as % of Total Cellular Content) after exposure to harmful microalgae (except TSCS187).
Error bars indicate standard deviations and letters on columns show significant differences among all experimental treatments after comparisons were performed across species. ANOVA, F0.05;54,55 = 210, p<0.001.
Fig 6.
Relationship between LDH-release and viability of gill cells after exposure to microalgae.
Red symbols represent Chattonella marina. Trend line and equation of linear adjustment are presented for all data (black line and top equation in black) and C. marina (red interrupted line and bottom equation in red). Error bars indicate standard deviations of LDH (x-axis) and viability (y-axis).
Fig 7.
Effect of algal extracts on gill cell viability.
Aqueous extracts of Alexandrium catenella (A), methanol extracts (B) and acetone extracts (C) of Chattonella marina, Fibrocapsa japonica and Heterosigma akashiwo (raphidophytes), Prymnesium parvum (haptophyte), and Karlodinium veneficum (dinoflagellate). Error bars represent standard deviations of quadruplicates, and asterisks or letters indicate significant differences among treatments within each concentration tested.
Fig 8.
Viability of gill cells after exposure to increasing concentrations of (A) brevetoxins and (B) PST toxins.
Error bars represent standard deviations of four replicates. Interrupted lines show LC50 values for each phycotoxin: PbTx-2 = 22.1 μg mL-1, PbTx-3 = 35.2 μg mL-1; GTX1&4 = 0.09 μg mL-1 GTX1 with 0.03 μg mL-1 GTX4, C1&C2 = 3.58 μg mL-1 C1 with 1.07 μg mL-1 C2, and STX = 1.71 μg mL-1. The epimer of greatest toxicity was included in the x-axis for toxins that are combined (i.e. GTX1 for the mix GTX1&4, and C2 for C1&C2). Letters next to the symbols in each line indicate significant differences among all treatments.
Fig 9.
Viability of gill cells after exposure to (A) Karlodinium veneficum and equivalent karlotoxin (KmTx-2) concentrations, (B) karlotoxin at different pH, and (C) karlotoxin at higher concentrations.
Error bars represent standard deviations of four replicates. The interrupted line in C shows LC50 values: 380 (3 hrs), 293 (4 hrs), and 203 ng mL-1 (5 hrs). Letters or asterisk on top of columns or next to the symbols in the lines indicate significant differences among treatments.
Table 2.
Fatty acid composition (as % of total fatty acids) in red tide phytoplankton.
Table 3.
Summary of impacts of microalgae on fish gill cells after a 2-hr exposure.
Highest values are in bold.
Table 4.
Summary of impacts of algae or toxins and substances produced by ichthyotoxic phytoplankton on viability of gill cells (RTgill-W1).