Étude expérimentale in situ des effets de la densité et de la quantité de nourriture chez le gastéropode Bithynia tentaculata (Mollusca: Prosobranchia)

Abstract

Experiments in a natural environment on the Gastropod Bithynia tentaculata showed that adult density and available food have significant effects on the growth of smaller adults and newborns. Mean length of the new generation at the end of the experiment incresed as adult densities decreased from the initial value and as food abundance increased. The only case of interaction between these two factors can be explained by an increase in the number of young brought about by the addition of food when density was low and by the influence of the density of these young on their growth. Different combinations of density and food can produce the various types of length–frequency histograms observed in a natural environment and during the past 8 years in the St. Lawrence River. There was no significant correlation between these two factors and the adult mortality rate, but density did have a significant effect on the mean number of young per adult.[Journal translation]

Factors affecting the structure of epiphytic gastropod communities in the St. Lawrence River (Quebec, Canada)

“…The total number of gastropods per unit of plant biomass increased considerably in 1984 because of the great abundance of A . tentaculata (Gilbert et al ., 1986 ;Vincent & Letourneau, 1985) are especially important within the epiphytic fraction of the population, which is numerically much important than the benthic fraction (Vincent et al, 1982). We are unable to explain this considerable increase for A .…”