Influence of environmental variables on the growth ofLeuciscus cephalus(Linnaeus 1766), in the River Durance, South-east France

Abstract

The chub, Leuciscus cephalus, colonizes the Durance river from its confluence with the Rhône river (alt. 13 m) up to the Serre Ponçon dam (alt. 780 m.). The Durance has been exposed to strong human pressure, notably dam construction, reduction of flow rate and perturbation of the natural zonation patterns. The linear growth of chub was studied by scale measurement at six stations in the Durance catchment area : two of which are located in its main tributaries, the Buech river and the Verdon. An analysis (ANOVA) of the mean size of fish from one to five years of age shows significant differences between the stations. Principal Component Analysis, in which the stations are characterized by eight nosological variables associated with the density of invertebrates and the number of degree-days above 12° and 22°C established a correlation between chub growth and species habitat, defined in terms of current flow rate, depth and substrate type and temperature. This correlation could be explained in two ways : 1-in slow-flowing homogenous riffle zone, the low water depth and absence of shelters limit the diversity of habitats and the biological richness; nevertheless the abundance of invertebrates does not seem to play an important role ; 2 -in zone of slow flowing riffles subjected to large daily and seasonal variations in water temperature, as in this mediterranean river, temperature might be quite high. Fish older than two years, therefore prefer zones of deep water, where the thermic inertia is stronger. Influences des variables

Influence of temperature on surface sediment disturbance by freshwater fish: a microcosm experiment

“…These species were selected according to their contrasted thermal requirements. B. barbatula is indeed a cold-to cool-water species whose upper tolerance limit does not exceed 19 xC (Elliott et al, 1996), while the two other cyprinid species prefer warmer waters with an optimum temperature ranging between 12 and 25 xC depending on species and regions (Horoszewicz, 1973;Mann, 1976;Elliott, 1981;Bouchard et al, 1998;Gozlan, 1998;Souchon and Tissot, 2012). When modelling the distribution of stream fish species at the European scale, Logez et al (2012) found a thermal range between 14.1 and 22.6 xC for the stone loach and between 14.7 and 25.8 xC for the chub.…”

Microgeographic genetic isolation in chub (Cyprinidae: Squalius cephalus) population of the Durance River: estimating fragmentation by dams

“…Indeed, the upper Durance is dominated by trout (Salmo trutta) while cyprinids such as chub are very rare (Bouchard et al 1998). This study only considered the lower part of the Durance delimited upstream by the reservoir of Serre-Ponçon and downstream by the confluence with the Rhône River.…”

“…This study only considered the lower part of the Durance delimited upstream by the reservoir of Serre-Ponçon and downstream by the confluence with the Rhône River. Indeed, the upper Durance is dominated by trout (Salmo trutta) while cyprinids such as chub are very rare (Bouchard et al 1998). Conversely, the lower parts are mainly inhabited by cyprinid species (e.g.…”

“…Indeed, the frequency of heterozygotes is assumed to be correlated to the population size (Wright 19311937, in Robertson 1962Frankham 1996;). In the case of the chub population of the Durance River, this hypothesis is very likely: (i) the upper part of the Durance section studied is characterised by a narrower channel than the lower one, and fish population sizes are often correlated to the amount of available habitat (Frankham 1996;Hanfling et al 2002); (ii) the fish community of the Durance shifts gradually from cyprinid to salmonid dominance (Bouchard et al 1998), which indicates that the upper parts of the river are suboptimal for cyprinids such as chubs and that a range-edge effect (Arnaud-Haond et al 2006) can occur; and (iii) it was more difficult to catch enough chubs in the most upstream sites. The second hypothesis is that the asymmetrical dispersion between the sampling points, due to the river flow and the obstacles, implies that downstream samples received more new alleles coming from upstream than the contrary.…”

Variability in the growth rate of chub Leuciscus cephalus along a longitudinal river gradient

“…Since the longitudinal river gradient is related to daily and seasonal variability in temperature, it is difficult to disentangle between the relative effects of temperature and habitat. Bouchard et al (1998) suggested that deep‐water areas with low current speed constitute some sort of hydraulic refuges, where low energy consumption associated with movements enhances growth rates. In natural water courses, the frequency of calm deep habitats increases progressively downstream, in accordance with the observed increase in growth.…”