SS1.09 Fisheries Population Linkage Spatial and Temporal Variation in Zooplankton
Date: Wednesday, June 12, 2002
Time: 2:45:00 PM
Location: Carson C
 
BourqueJF, GIROQ, Laval University, Quebec, Canada, bourquinet@hotmail.com
Dodson, J, J, GIROQ, Laval University, Quebec, Canada, julian.dodson@bio.ulaval.ca
Marcogliese, D, J, Environment Canada, St. Lawrence Centre, Montreal, Canada, david.marcogliese@ec.gc.ca
 
IMPACT OF THE TRANSMISSION OF A COPEPOD PARASITE ON THE DISTRIBUTION AND GROWTH OF SMELT LARVAE
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The potential links between zooplankton and fish populations are not only trophic ones. In the St. Lawrence Middle Estuary, a population of Eurytemora affinis transfers an intestinal parasite to rainbow smelt larvae (Osmerus mordax). These larvae accomplish vertical migrations to achieve retention in the estuarine turbidity maximum (ETM) and parasitism is suspected to affect this behavior. The larvae were collected in summer 1996 and 2001 before and after the arrival of the parasite in the ETM. We develop a parasite infestation strength index taking into consideration the size of the parasite and the intensity of infection. Individual growth trajectories and hatch-date distributions were reconstructed using otolith microstructure. The parasitism index is not significatively different between larvae found in the bottom and upper layer during ebbs or flood indicating that parasitism is not affecting directly the vertical distribution of the larvae. However, parasitism affects growth rate thus diminishing the survival of larvae. Changes in the dynamics of the first host (E. affinis) may thus impact smelt recruitment.