Chattonella subsalsa (Raphidophyceae) growth and hemolytic activity in response to agriculturally-derived estuarine contaminants.

The potential for toxic contaminants and nutrient pollution to alter natural cycles of estuarine phytoplankton blooms is well known, yet few studies have examined how these combined stressors affect harmful algal species. Here, a robust testing protocol was developed to enable an ecotoxicological assessment of responses to commonly co-occurring estuarine contaminants by harmful algal bloom species. The population growth and toxicity (as cell density and hemolytic activity, respectively) of a cultured strain of the toxigenic raphidiophycean, Chattonella subsalsa, were assessed in two experiments (duration 10 days and 28 days) across a gradient of atrazine concentrations and N:P ratios simulating nutrient-rich versus nutrient-depleted regimes.

Imbalanced nutrient regimes increase Prymnesium parvum resilience to herbicide exposure.

The toxigenic haptophyte Prymnesium parvum is a mixotrophic phytoplankter with an extensive historic record of forming nearly monospecific, high-biomass, ecosystem-disrupting blooms, and it has been responsible for major fish kills in brackish waters and aquaculture facilities in many regions of the world. Little is known about how this species responds to commonly occurring environmental contaminants, or how nutrient (nitrogen, phosphorus) pollution may interact with environmentally relevant pesticide exposures to affect this harmful algal species. Here, standard algal toxicity bioassays from pesticide hazard assessments were used along with modified erythrocyte lysis assays to evaluate how atrazine exposures, imbalanced nutrient supplies, and salinity interact to influence the growth and toxicity in P.

Assessment of atrazine toxicity to the estuarine phytoplankter, Dunaliella tertiolecta (Chlorophyta), under varying nutrient conditions.

Anthropogenic inputs of chemical environmental contaminants are frequently associated with developing harmful algal blooms, but little is known about how estuarine phytoplankton assemblages respond to multiple, co-occurring chemical stressors in chronically disturbed habitats. The goals of this research were to establish a robust protocol for testing the effects of atrazine on estuarine phytoplankton, and then to use that protocol to compare the effects of atrazine exposure with and without nutrient enrichment on a cosmopolitan estuarine/marine alga, Dunaliella tertiolecta (Chlorophyta). Atrazine sensitivity in nutrient-replete media (96-h growth inhibition [Formula: see text]) was 159.