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Marine
and Estuarine Science Program BSc University of
New Hampshire (1997) wildsea@earthlink.net |
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Project
Title: Comparative reproductive events of the invasive Varnish clam, Nuttalia obscurata, and the fisheries Littleneck clam, Venerupis philippinarum.
Abstract:
The Purple Varnish Clam (Nuttallia obscurata), a rapidly
spreading introduced species in Washington, has invaded commercial
fisheries beds of the Manila Clam (Venerupis philippinarum).
Characteristics of population biology are important to understanding
the success
of an invading species. This study was conducted to investigate
two
aspects of population dynamics for N. obscurata and V.
philippinarum, the duration of spawning events, and the occurrence
of recruitment. Nuttallia obscurata displayed earlier
spawning events, earlier recruitment events, and greater recruitment
densities than V. philippinarum. There was temporal and
spatial variability in recruitment events for N. obscurata,
maintaining large populations on many beaches. Nuttallia
obscurata recruitment did not appear limited by adult densities,
while V. philippinarum adults are known to negatively impact
recruitment success. Differential larval periods combined with
high adult survival provide an ecological advantage over spatially
competitive species such as V. philippinarum.
I was funded by the Padilla Bay National Estuarine Research Reserve (State of WA Dept. of Ecology, NOAA) and the Biology department at WWU.