Habitat quality enhances spatial variation in the self-thinning patterns of stream-resident brown trout (Salmo trutta)

$50.00 plus tax (Refund Policy)

Buy Article:

Abstract:

This study explored the extent to which variation in habitat factors related to growth and density influence self-thinning patterns in stream-living brown trout (Salmo trutta). Analysis of 110 cohorts at 12 sites of four contrasting streams revealed density–mass relationships in two phases. Density of survivors decreased little during the first half of their lifetime. A second phase commenced as individuals attained a threshold mass upon which density declined linearly with increased mass. The slopes of the second phase were greater than predicted by space and food demands. Among sites, these slopes were related to threshold densities at the beginning of the second phase. In turn, elevations, threshold densities, and slopes depicted concave trajectories against site depth, whereas threshold masses increased linearly. Apparently, cohorts remain below the carrying capacity during the first half of their lifetime and self-thin during the second half. Space-limited habitats impose site-specific carrying capacities and site-specific self-thinning coefficients, suggesting a common mechanism underlying self-thinning and an unanticipated, emerging property: two-phase patterns with far more variation in self-thinning coefficients. Variability in growth and density exhibited by brown trout and other salmonids across regions suggests that two-phase patterns may occur broadly, and self-thinning coefficients may vary widely.

La présente étude explore dans quelle mesure la variation des facteurs de l'habitat reliés à la croissance et la densité influence les patrons d'auto-éclaircie chez des truites brunes (Salmo trutta) vivant en eau courante. L'analyse de 110 cohortes à 12 sites dans quatre cours d'eau bien différents indique deux phases dans les relations densité–masse. La densité des survivants diminue peu durant la première moitié de la vie des poissons. Une deuxième phase débute lorsque les individus atteignent une masse seuil au-delà de laquelle la densité diminue en fonction linéaire de l'accroissement de masse. Les pentes de cette seconde phase sont plus fortes que ne permettent de le prédire les besoins en espace et en nourriture. Parmi les sites, ces pentes sont reliées aux densités seuils au début de la seconde phase. En séquence, l'altitude, la densité seuil et la pente décrivent des trajectoires concaves en fonction de la profondeur du site, alors que la masse seuil augmente de façon linéaire. Il semble que les cohortes demeurent sous le stock limite durant la première moitié de leur cycle et procèdent à une auto-éclaircie durant la seconde moitié. Les habitats limités en espace imposent des stocks limites et des coefficients d'auto-éclaircie spécifiques au site, ce qui laisse croire à un mécanisme commun sous-jacent à l'auto-éclaircie et une caractéristique émergente inattendue, soit des patrons biphasiques avec beaucoup plus de variation dans les coefficients d'auto-éclaircie. La variabilité de la croissance et de la densité observée chez la truite brune et d'autres salmonidés dans les diverses régions indique que les patrons biphasiques peuvent se produire sur une grande échelle et que les coefficients d'auto-éclaircie peuvent varier considérablement.

Document Type: Research Article

Publication date: September 1, 2008

More about this publication?
  • Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Terms & Conditions
  • Sample Issue
  • Reprints & Permissions
  • ingentaconnect is not responsible for the content or availability of external websites
Related content

Tools

Favourites

Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more