Fabrice Teletchea

Strong Effects of Temperature on the Early Life Stages of a Cold Stenothermal Fish Species, Brown Trout (Salmo trutta L.).

Temperature is the main abiotic factor that influences the life cycle of poikilotherms. The present study investigated the thermal tolerance and phenotypic plasticity of several parameters (development time, morphometric measures, bioenergetics) for both embryos and fry of a cold stenothermal fish species, brown trout (Salmo trutta L.) in order to allow for a holistic evaluation of the potential effects of temperature. Five temperatures (4°C, 6°C, 8°C, 10°C, and 12°C) were tested, and the effects of temperature were analyzed at three stages: hatching, emergence, and first food intake. A mean of 5,440 (S.E. ± 573) eggs, coming from seven females and seven males (seven families) captured close to Linkebeek (Belgium), were used for each temperature. Maximum survival of well-formed fry at first food intake and better use of energy budget were found at 6°C and 8°C, temperatures at which the possible contribution to the next generation should therefore be greatest. At 12°C, the experimental population fell dramatically (0.9% survival rate for well-formed fry at first food intake), and fry had almost no yolk sac at first food intake. The present results on survival at 12°C are in accordance with predictions of a sharp decrease in brown trout numbers in France over the coming decades according to climate change projections (1°C to 5°C temperature rise by 2100 for France). At 10°C, there was also a lower survival rate (55.4% at first food intake). At 4°C, the survival rate was high (76.4% at first food intake), but the deformity rate was much higher (22% at first food intake) than at 6°C, 8°C, and 10°C. The energetic budget showed that at the two extreme temperatures (4°C and 12°C) there was less energy left in the yolk sac at first food intake, suggesting a limited ability to survive starvation.

Domestication and Genetics: What a Comparison Between Land and Aquatic Species Can Bring?

Domestication , which is by definition a long and endless process, was one of the most significant cultural and evolutionary transitions of human history. In land, the domestication of animals started about 12,000 years ago and resulted in an apparent dichotomy between domesticated and wild animals. Nevertheless, new findings suggest that long-term gene flow between wild and captive land animal populations was much more common than previously assumed challenging assumptions about genetic bottlenecks during domestication, expectations about monophyletic origins, and interpretations of multiple independent domestication events. Besides, it raises new questions regarding ways in which behavioral and phenotypic domestication traits were maintained, and just what a domestic population was. In contrast to land animals, the onset of the domestication of aquatic species is a recent phenomenon, which started in the 1980s for most species. Hence, today there are still lots of exchanges between wild and captive individuals, and thus, captive fish have only slightly changed from their wild congeners. To better describe the diverse strategies for fish production, a new classification was recently developed comprising five levels of domestication with 1 being the least domesticated to 5 being the most domesticated. The recent domestication of fish species, and the diversity of domestication levels, provides a unique opportunity to better understand how genetic variability evolves during the early phases of fish domestication that could also be useful to discuss both the domestication history of land animals and concepts, such as domestication itself and the differences between wild and domesticated animals.

How climate change may affect the early life stages of one of the most common freshwater fish species worldwide: the common carp (Cyprinus carpio)

Abstract The aim of the present study is to test the effects of temperature on the early life stages of one of the most common freshwater fish species worldwide, the common carp. About 16,000 eggs coming from 3-year-old broodstock were randomly distributed into five incubators, one incubator by tested temperature (16, 18, 20, 22, and 24°C). Several parameters (survival and malformation rates, development time, morphometric parameters, and energy values) were studied at three key biological stages (hatching, emergence and first food intake). We found no significant impact of temperature on both survival and malformation rates. However, as expected, development time was three times longer at 16°C than at 24°C. At both 16 and 24°C, the consumption of the yolk sac was highest; yet larvae were smaller at 16°C and largest at 24°C. Our results suggest that the early life stages of common carp developing at 22–24°C could survive better in the wild, which is in accordance with current models that predict a small change of the distribution area of the common carp in France, but probably an extension in Northern European regions, in the next decades consequently to climate change.