Bosch, I., E. Beary and  E. Decker, 1996. Lunar Periodicity of Synchronous Spawnings by Dreissena polymorpha in Conesus Lake, New York,  State University of New York, College at Geneseo

Abstract from The Sixth International Zebra Mussel and Other Aquatic Nuisance Species Conference, Dearborn, Michigan, March 1996

Lunar Periodicity of Synchronous Spawnings by Dreissena polymorpha in Conesus Lake, New York

Spawnings in recently established populations of the zebra mussel appear to be highly synchronous. While chemical cues in the spawn likely contribute to the propagation of gamete release within a population, the environmental cue(s) that initiate the spawning episodes have not been identified. We studied the reproductive patterns of a recently established population of zebra mussels in Conesus Lake, western New York, by following the production and growth of larval cohorts on at least a weekly basis during the spring and summer of 1995. The first three of four mass spawnings in the 1995 reproductive season, during which at least 50% of the larvae surveyed were of the smallest size classes (<110µm), occurred sometime between June 1-8, July 8-10 and August 5-10. All three of these spawnings coincided with a series of bright, moon-lit nights, while the July and early August spawning dates encompassed the full moon phase. PAR light measurements indicated that on cloudless nights, moonlight penetrated into shallow waters (<2 m) occupied by significant numbers of adult mussels in Conesus Lake. A fourth, less synchronized spawning of zebra mussels in late August, out of phase with the full moon, may have been triggered by decreasing water temperatures in the lake. Our hypothesis of a lunar periodicity in spawning of the zebra mussel is consistent with observations of synchronized spawnings in Lake Erie, USA during 1989 and 1990 (e.g. Haag and Gordon, 1993) which followed closely the lunar periodicity observed in Conesus Lake. Larval cohort data from studies of older populations (e.g. Sprung 1989) reveal a more irregular pattern of larval production, although large spawnings still occurred about the time of the full moon. Further review of the literature and empirical study should reveal the geneality of this phenomenon.

Keywords: Zebra_mussel, Population_dynamics, Basic_biology
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