Low pH preempts bloom development of a toxic haptophyte

• Published in: Harmful algae Vol. 20; pp. 156 - 164
• Main Authors: Prosser, Krista N., Valenti, Theodore W., Hayden, Natanya J., Neisch, Michael T., Hewitt, Natalie C., Umphres, George D., Gable, George M., Grover, James P., Roelke, Daniel L., Brooks, Bryan W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01-12-2012; Elsevier
• Subjects: Algae; Animal and plant ecology; Animal, plant and microbial ecology; anthropogenic activities; Aquatic life uses; Autoecology; Biological and medical sciences; biomass; Cladocera; Climate change; Fundamental and applied biological sciences. Psychology; Harmful algal bloom; Invasive species; lakes; phytoplankton; Plant cytology, morphology, systematics, chorology and evolution; Plants and fungi; population density; Prymnesium; Prymnesium parvum; Thallophyta; toxicity; Water quality; zooplankton; United States; USA; Climate change; Invasive species; Harmful algal bloom; Aquatic life uses; Prymnesium parvum; Water quality; Toxicity; Algae; Haptophyta; Dynamical climatology; Aquatic environment; Bloom; Development; pH; Harmful alga
• ISSN: 1568-9883; 1878-1470
• DOI: 10.1016/j.hal.2012.10.002

► A number of factors influence the development of Prymnesium parvum blooms; pH influences the magnitude of ambient toxicity caused by these blooms. ► In two 21d studies examining pre-bloom and bloom development conditions, neutral pH levels preempted harmful P. parvum bloom development. ► Population densities of P. parvum never reached bloom proportions at pH 7 or 7.5; however, harmful blooms occurred at higher pH (8.5). ► Here we report for the first time that pH appears to govern P. parvum bloom formation and associated toxicity to aquatic life in inland waters.
Harmful blooms of Prymnesium parvum in inland waters continue to expand, in part, due to anthropogenic influences and climate change. Several studies have identified the importance of elevated pH on increasing ambient toxicity associated with P. parvum in inland, coastal and marine systems. Influence of pH on P. parvum bloom dynamics, however, is less understood. Here, we evaluate whether pH influences P. parvum bloom development and ambient toxicity. We manipulated pH levels (7, 7.5, 8.5) of in situ experimental enclosures during 21d pre-bloom and bloom development experiments in Lake Granbury, TX, USA, an impoundment consistently impacted by P. parvum blooms. Neutral pH levels preempted P. parvum bloom development. Population densities never reached bloom proportions and no ambient toxicity to fish or cladocerans resulted. However, higher pH (8.5) allowed bloom formation to occur and resulted in ambient toxicity. During both experiments, reducing pH to 7 and 7.5 did not adversely affect phytoplankton or zooplankton biomass. Observations from this study provide initial evidence that pH appears to be a major factor governing P. parvum bloom formation and associated ambient toxicity in inland waters. This research further highlights the importance of developing an understanding of interactions among harmful blooms of P. parvum and pH responses in inland waters to anthropogenic activities and climatic changes.