Title

The role of temperature in life history traits variability: a case study on the bullhead, Cottus gobio L., at the drainage network scale (Bez, France)  

Author(s) / Editor(s)

Abdoli, A.

Content Language(s)

French

Type of Document

Thesis / dissertation

Document Status

Final

Document Availability

Reference/Abstract

Abstract / Description

Increasing continental water temperature in response to climatic warming will probably change life history traits and geographical distribution patterns of fishes in river habitats. In this study, the hypothesis of environmentally related life history traits (mainly with water temperature) was tested by using between-site comparisons within a spatially structured population of bullhead (Cottus gobio), a small bottom-dwelling species restricted to cold waters. The studied drainage system (Bez river and tributaries, South-Eastern France) is situated in an undisturbed small catchment. It is characterized by a strong thermal heterogeneity, in relation with its complex hydrology and by an active bedload transport of coarse sediment. The effects of water temperature, female length and fish densities on bullhead egg production were investigated for different age classes. All the 6 local populations presented synchronous oocyte development (one single annual batch per female). When statistically significant, fecundity and egg size were always positively correlated with water temperature, and always negatively correlated with fish densities. Fecundity was always positively correlated with female size, whatever the age class considered. In contrast, egg size and net annual reproductive effort were positively correlated with female body size only in females reaching maturity (2 years old), whereas there was no relationship between these parameters for older females (3 and 4 years old). Effects of water temperature on growth rate, age at maturity and longevity were investigated on the same 6 sites. Otolithometry was used to age 545 bullheads. Maximum age observed was 6 years for males and 7 years for females. Age at first reproduction ranged from 1 to 3 years. Females matured quickly and at a larger size when water temperature was higher. Fish longevity was lower in the warmest sites. Water temperature also significantly influenced parameters L∞ and K in von Bertalanffy growth curves, but thermal influence on annual growth rates varied, depending of the age class. Growth rate of young bullheads (0 and 1 ) increased with temperature, whereas it decreased in older fish. The spatial distribution of the different age classes was analyzed in the entire water network, by continously collecting environmental and biological data at a coarse spatial scale (every 750 m). Forty one sampling sites covered the 31 km of the drainage network, and allowed to define the habitat space potentially occupied by bullhead. Bullhead densities varied locally between 0 and 4.4 individuals per m2, leading to a total population size of about 150 to 300.103 individuals. Temperature during the growing season positively affected only the densities of young bullheads (1 and 2 ), and densities of all age classes were negatively correlated with bedload sediment size. Mean age and survival rates of local populations were negatively correlated to water temperature. These results demonstrate that a moderate increase in temperature (3 degrees C, i.e. the range of thermal change predicted by IPCC scenarios) on age-structured populations of bullhead could greatly affect their life history traits, age structure, and densities. Further experimental studies and long-term surveys of populations are needed to confirm these findings. Bullhead appears as a good sentinel species to investigate the effects of global warming on fish populations in rivers.

Keywords

FISH; TEMPERATURE; POPULATION DYNAMICS; POPULATION DENSITY; FECUNDITY; EGGS; SEXUAL MATURITY; HABITAT; RIVERS

Geographic Keywords

SOUTHEASTERN FRANCE

Date of Publication/Issue

May 2005

Publisher (Owner)

University Lyon-1

Publication Location

Lyon, France

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Target Audience

Researchers and Academics; Policy Makers

Topics this item is listed under

Research & Methods [1641]