Abstract
Zooplankton with calcareous skeletons are birefringent under cross-polarized light, and thus this technique can be quite useful, indeed sometimes almost essential, for the detection and enumemeration of these types of organisms in plankton samples. A simple and inexpensive application of this technique is described and illustrated with quantitative examples from research on the veligers of the zebra mussel Dreissena polymorpha (Pallas). The time required to detect veligers in plankton samples was decreased by an order of magnitude; the accuracy of counts was substantially improved (15% more than controls), and the time required for counts was greatly reduced (41% of control times). This technique is especially useful in situations in which veligers are difficult to find or see (e.g., at low densities, in samples ‘cluttered’ with extraneous organisms or material) or when the investigator is inexperienced with plankton sampling and planktonic organisms. The major limitations are its inability to discriminate among various bivalve species that have planktonic larvae and the similar appearance of ostracods which also have calcareous shells. Expanded use of this technique should (1) increase our ability to use plankton sampling for the early detection of veligers during range expansion and reproductive cycles and (2) permit more accurate estimates of veliger abundance.
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References
Bennett, H. S., 1950. Methods applicable to the study of both fresh and fixed material: The microscopical investigation of biological materials with polarized light. In R. M. Jones (ed.), McClung's Handbook of Microscopical Technique, 3rd edn. Hoeber, New York: 591–677.
Boolootian, R. A., 1959. A simple technique for studyingin vivo skeletal structures of echinoderm larvae. Turtox News 37: 115.
Conn, D. B., R. A. Lutz, Y. Hu & V. S. Kennedy, 1993. Guide to the identification of larval and post-larval stages of the zebra mussel Dreissena spp. and the false dark mussel Mytilopsis leucophaeata. New York Sea Grant Institute, Stony Brook (NY), 22 pp.
Gallager, S., J. P. Bidwell & A. M. Kuzirian, 1989. Strontium is required in artificial seawater for embryonic shell formation in two species of bivalve molluscs. In R. E. Crick (ed.), Origin, evolution, and modern aspects of biomineralization in plants and animals. Plenum Press, New York: 349–366.
Holland-Bartels, L. E., S. K. Littlejohn & M. L. Huston, 1990. A guide to larval fishes of the upper Mississippi River. USFWS National Fisheries Research Center, La Crosse, WI, 107 pp.
Kraft, C., 1993. Early detection of the zebra mussel. In T. F. Nalepa & D. W. Schloesser (eds), Zebra mussels: biology, impacts, and control. Lewis Publishers, Ann Arbor (MI): 705–714.
Marsden, J. E., 1992. Standard protocols for monitoring and sampling zebra mussels. Illinois Natural History Survey Biological Notes 138, 40 pp.
Nalepa, T. F. & D. W. Schloesser (eds), 1993. Zebra mussels: biology, impacts, and control. Lewis Publishers, Ann Arbor (MI): 810 pp.
Nichols, S. J. & M. G. Black, 1994. Identification of larvae: zebra mussel (Dreissena polymorpha), quagga mussel (Dreissena bugensis), and the Asian clam (Corbicula fluminea). Can. J. Zool. 72: 406–417.
Pennington, J. T. & M. G. Hadfield, 1989. A simple nontoxic method for the decalcification of living invertebrate larvae. J. exp. mar. Biol. Ecol. 130: 1–7.
Roughgarden, J., W. Iwasa & C. Baxter, 1985. Demographic theory for an open marine population with space- limited recruitment. Ecology 66: 54–67.
Schaner, T., 1990. Detection of zebra mussel veligers in plankton samples using sugar solution. Lake Ontario Fisheries Unit Annual Report, LOA 91.1, Ontario Ministry of Natural Resources, Picton (ON), 3 pp.
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Johnson, L.E. Enhanced early detection and enumeration of zebra mussel (Dreissena spp.) veligers using cross-polarized light microscopy. Hydrobiologia 312, 139–146 (1995). https://doi.org/10.1007/BF00020769
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DOI: https://doi.org/10.1007/BF00020769