Comparative Toxicity ofPrymnesium parvumin Inland Waters1

Brooks, Bryan W., Susan V. James, Theodore W. Valenti, Jr., Fabiola Urena‐Boeck, Carlos Serrano, Jason P. Berninger, Leslie Schwierzke, Laura D. Mydlarz, James P. Grover, and Daniel L. Roelke, 2010. Comparative Toxicity ofPrymnesium parvumin Inland Waters.Journal of the American Water Resources Association(JAWRA) 46(1):45‐62. DOI: 10.1111/j.1752‐1688.2009.00390.x Abstract: Numerous studies have examined the impacts ofPrymnesium parvumto aquatic life, but the majority of information available is from experiments or field studies performed at salinities of marine and coastal ecosystems. Ambient toxicity ofP. parvumhas been characterized within vitroandin vivomodels because reliable quantitation ofP. parvumtoxins in environmental matrices is often precluded by a lack of available analytical standards. Hemolytic activity and fish mortality assays have been used most frequently to characterize toxic conditions; however, relatively fewin vivostudies employed standardized methods. Because the relative sensitivities of different taxa toP. parvumtoxins in inland waters were undefined, we assessed the comparative toxicity ofP. parvumfiltrate from a laboratory study (20°C, 12:12 light:dark cycle, f/8 media, 2.4 psu) to several common standardizedin vitroandin vivomodels. After exposure to cell‐free filtrate hemolytic activity (1 h EC50 = 13,712 cells/ml) and juvenile fish (Pimephales promelas) survival (48 h LC50 = 21,754 cells/ml) were the most sensitive assay responses examined, followed by rotifer (Brachionus calyciflorus) population growth rate [48 h no observable adverse effect levels (NOAEL) = 19,072 cells/ml] and cladoceran (Daphnia magna) reproduction (10‐day NOAEL = 47,680 cells/ml). Green algae (Pseudokirchneriella subcapitata) growth (96 h) was not adversely affected but was instead significantly stimulated byP. parvumtoxins. We further propose an initial species sensitivity distribution approach forP. parvum, which may be used to support future environmental management decisions. Our findings from these laboratory studies indicate that although fish kills are increasingly associated withP. parvumblooms occurring in inland waters, further study is required to define the influences of toxin sensitivities of phytoplankton, zooplankton, and fish communities onP. parvumbloom initiation and termination.