Seasonal reproductive allocation, local-scale variation and environmental infl uences on life history traits of introduced pumpkinseed (Lepomis gibbosus) in southern England
Fox, Michael G.; Villeneuve, François; Copp, Gordon H.
published: Feb 1, 2011
ArtNo. ESP141017803005, Price: 29.00 €
Seasonal reproductive allocation in the wild was assessed during the 2004 spawning season in non-native populations of multiple-spawning pumpkinseed sunfish in England to: i) estimate total seasonal reproductive allocation and assess local-scale variation, ii) determine if differences in population density, somatic growth rate, body mass, body condition or ecosystem productivity can explain differences in local-scale reproductive allocation; and iii) assess whether differences in ecosystem productivity can explain interpopulation variation in growth and life history traits in these populations. In the three physically connected ponds, among-population estimates of mean reproductive allocation of females varied almost two-fold, ranging from 17-37 % of somatic weight in the base model and 5-19 % of somatic weight using a more conservative assumption on the GSI of females assumed to be spawning in a two-week period. Temporal trends in reproductive allocation varied among these populations in both periodicity and intensity, but one population that experienced a recent crash had only a single peak of reproductive activity in late July. Estimates of the number of spawning bouts per female varied more than two-fold between the highest and lowest population. Mean total phosphorus concentration in 14 English ponds containing pumpkinseed varied from 30-338 μg L-1. There were no significant correlations between measures of productivity and either growth or life history traits of pumpkinseed populations in these ponds, suggesting that above a certain level, higher phosphorus concentrations will not influence these traits through bottom-up trophic effects.