Controlling the Invasive Diatom Didymosphenia geminata: An Ecotoxicity Assessment of Four Potential Biocides

• Published in: Archives of environmental contamination and toxicology Vol. 61; no. 1; pp. 115 - 127
• Main Authors: Jellyman, P. G., Clearwater, S. J., Clayton, J. S., Kilroy, C., Blair, N., Hickey, C. W., Biggs, B. J. F.
• Format: Journal Article
• Language: English
• Published: New York Springer-Verlag 01-07-2011; Springer; Springer Nature B.V
• Subjects: Algae; Analysis; Animal, plant and microbial ecology; Animals; Applied ecology; Aquatic ecosystems; Aquatic plants; Bacillariophyceae; Biocides; Biological and medical sciences; Chlorophyta - drug effects; Cladding; Cladocera; Copper; Copper Sulfate - toxicity; Creeks & streams; Daphnia - drug effects; Diatoms - drug effects; Dicarboxylic Acids - toxicity; Didymosphenia geminata; Earth and Environmental Science; Ecosystems; Ecotoxicology; Ecotoxicology, biological effects of pollution; Edetic Acid - toxicity; Environment; Environmental Chemistry; Environmental Health; Fish; Freshwater; Freshwater ecosystems; Freshwaters; Fundamental and applied biological sciences. Psychology; General aspects; Health risks; Herbicides - toxicity; Interceptors; Introduced Species; Laboratories; Monitoring/Environmental Analysis; Mortality; Native species; Neutralization; New Zealand; Nonnative species; Oncorhynchus mykiss; Perciformes; Pesticides; Pinus - toxicity; Plankton; Plant cytology, morphology, systematics, chorology and evolution; Plant Oils - toxicity; Pollution; Product testing; Rivers; Soil Science & Conservation; Streams; Studies; Thallophyta; Toxicity; Toxicity testing; Toxicity Tests, Acute; New Zealand; Rainbow Trout; Algaecide; Biocide; Fish Mortality; Exposure Solution; Heterokontophyta; Pollution; Bacillariophyta; Ecotoxicology; Toxicity; Algae; Environment; Population dynamics; Invasion
• ISSN: 0090-4341; 1432-0703
• DOI: 10.1007/s00244-010-9589-z

In 2004, an invasive mat-forming freshwater diatom,
Didymosphenia geminata
(didymo), was found in New Zealand causing concern with regard to potential consequences for local freshwater ecosystems. A four-stage research program was initiated to identify methods to control
D. geminata
. This article reports the results of Stage 2, in which four potential control compounds [Gemex™ (a chelated copper formulation), EDTA, Hydrothol
®
191, and Organic Interceptor™ (a pine oil formulation)] selected in Stage 1 were evaluated for their biocidal efficacy on
D. geminata
and effects on non-target organisms using both artificial stream and laboratory trials. Artificial stream trials evaluated the mortality rates of
D. geminata
and fishes to three concentrations of the four biocides, whereas laboratory toxicity trials tested the response of green alga and cladocera to a range of biocide concentrations and exposure times. In artificial stream trials, Gemex and Organic Interceptor were the most effective biocides against
D. geminata
for a number of measured indices; however, exposure of fishes to Organic Interceptor resulted in high mortality rates. Laboratory toxicity testing indicated that Gemex might negatively affect sensitive stream invertebrates, based on the cladoceran sensitivity at the proposed river control dose. A decision support matrix evaluated the four biocides based on nine criteria stipulated by river stakeholders (effectiveness, non-target species impacts, stalk removal, degradation profile, risks to health and safety, ease of application, neutralization potential, cost, and local regulatory requirements) and Gemex was identified as the product warranting further refinement prior to an in-river trial.