AB 18:209-215 (2013)  -  DOI: https://doi.org/10.3354/ab00509

Separation strategies for invertebrate dormant stages contained in sediment

Elizabeta Briski1,*, Sarah A. Bailey 1, Hugh J. MacIsaac

1Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, Ontario L7R 4A6, Canada
2Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4, Canada

ABSTRACT: To accurately assess community composition of invertebrates, both active and dormant life stages should be considered. Dormant stages are typically produced as a strategy to overcome inhospitable environmental conditions and can also facilitate species dispersal. While they often sink and accumulate in sediment of natural habitats forming ‘egg banks,’ dormant stages are also found in the sediments accumulated in ships’ ballast tanks. Recent studies have used 2 different methods to separate dormant stages from ballast sediment to assess invasion risk associated with ballast tanks: the colloidal silica sol Ludox HS 40 and sugar flotation (i.e. the Onbé-Marcus method). It has been assumed that the Ludox HS 40 method is most effective for separation but reduces dormant stage viability whereas sugar flotation has lower separation efficacy but higher resulting viability. We conducted a comparative assessment of the 2 methods by separating dormant stages from 160 ballast sediments and examining resulting abundance counts, hatching results, DNA extractions and PCR amplifications. We found no difference in the results between the methods. The financial cost of sugar flotation is lower than that of Ludox HS 40, and costs can be further reduced by using only 1 method instead of both due to lower labour costs, particularly for a large number of samples.

KEY WORDS: Colloidal silica sol Ludox HS 40 · Method comparison · Onbé-Marcus method · Sugar flotation

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Cite this article as: Briski E, Bailey SA, MacIsaac HJ (2013) Separation strategies for invertebrate dormant stages contained in sediment. Aquat Biol 18:209-215. https://doi.org/10.3354/ab00509

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