TOWARD DEVELOPMENT OF A GREAT LAKES RELEVANT BWMS TESTING PROTOCOL: USE OF STAINS TO ASSESS VIABILITY OF RESTING STAGES

Abstract

United States Coast Guard and International Maritime Organization rules developed to minimize the spread of aquatic nuisance species (ANS) in the ballast of commercial ships regulate indicator microbes, protists and zooplankton, determining protist survival using staining techniques and zooplankton survival based on organism motility. The density of eggs and resting stages in ballast discharge are not regulated when assessing the effectiveness of ballast water treatment systems although they can be present in meaningful densities, potentially increasing the likelihood of ANS spread. To date, viability of freshwater zooplankton resting stages has been determined by grow out methods which are time consuming and use light, temperature and media regimens that may not be appropriate for all species. Stains have been used to assess viability of freshwater protists in the regulated size class, as well as salt water zooplankton resting stages. This paper examines the effectiveness of two stains, aniline blue and TO-PRO-1 Iodide, at assessing viability of Daphnia magna ephippia and Brachionus calyciflorus cysts.