Large‐scale synchrony and inter‐annual variability in roach recruitment in the Rhône River: the relative role of climatic factors and density‐dependent processes

摘要: 1. We report patterns of temporal variation in the recruitment roach (Rutilus rutilus). The data consist annual abundance first 2 year-classes, 0 + and 1 fish, at four sites Rhone River (France) between 1987 1997. Over this 11-year period both fish fluctuated strongly. 2. Cross-correlation indicated high spatial synchrony dynamics, although correlations among dynamics were weaker. No clear pattern was apparent relationship level distance pairs sites. 3. could be attributable to large-scale variations weather, influencing water temperature. Total body length correlated with temperature (expressed degree-days over 12 °C), main factor explaining inter-annual cohort size. Monthly abiotic factors (measured by standard deviation discharge) did not influence fluctuations. Correlations June suggest that year-class strength mainly determined during few months life. 4. absence fluctuations suggests little correlation survival conditions year life, other survival. 5. Survival density-dependent. Intraspecific competition within thus older age-classes. 6. implications age- or stage-dependent for species complex life histories are discussed. Studying different history stages enhance our understanding population spatially structured species.