39th Annual Larval Fish Conference, 12-17 juillet, Vienne (Vienna), Autriche
Realis, E., Hamani, V., Fontaine, P., Pasquet, A., Teletchea, F.
2015
Global warming is one of the main human perturbations, with destruction of habitats, introduction of alien species, pollution and overexploitation, that will probably reduce the most biodiversity throughout the world. For fish species, the current models predict that global warming will impact more strongly cold stenothermal species rather than eurytherm or warm stenotherm species. In addition, the impact on the early stages will be more important because these stages are the most stenothermal during the fish life cycle.
The present study aims at evaluating the effect of five temperatures on the ecology valence of eurythermal fish (8, 10, 12, 14 and 16°C) during the entire yolk-feeding period (embryo and larvae). For this study, the effects of temperature on various parameters were analyzed, among which survival rate, malformations, development time and morphometrics (e.g., larval size at hatching), at three specific stages during development: hatching, emergence and mixed feeding. About 60 000 eggs coming from 6 males and 6 females were used for each temperature. During this study we observed these parameters on yolk-feeding period (hatching, emergence and mixed feeding step). This study show that time required to reach a given ontogenetic stage decreased significantly with increasing temperature (between fertilization to hatching at 8°C: 20 days, at 10°C : 14days, at 12°C:10 days at 14°C:9 days and at 16°C: 7 days). Moreover, temperature have a significant impact of during of hatching (average 2 days at each temperature expect 8°C with 5 days) which will create a strong heterogeneity of size. However, the temperature seems to have no effect on survival rate and deformity rate at hatching. This study confirms that temperature is a key abiotic factor for time required to reach a given ontogenetic stage and morphometric parameters of this specie. During this study we tested the ecological valence of northern pike. More in terms of absolute value for the current thermal tolerances an increase or a decrease temperatures hasn’t impact on the survival rate, this rate should be taken into account in the current model, these are based mainly tolerances thermal adults. This data should be taken into consideration into models of forecast for the repartition.
This study and the Phd scholarship were financed by ONEMA.