Environmental determinants of recruitment and their influence on the population dynamics of stream-living brown trout Salmo trutta

• Published in: Oikos Vol. 105; no. 3; pp. 641 - 646
• Main Authors: Lobon-Cervia, J, Rincon, P A
• Format: Journal Article
• Language: English
• Published: Copenhagen Munksgaard International Publishers 01.06.2004; Blackwell Publishers; Blackwell
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Biological and medical sciences; Demecology; Freshwater; Freshwater ecology; Freshwater fishes; Fundamental and applied biological sciences. Psychology; Marine fishes; Population dynamics; Population ecology; Salmo trutta; Stream habitats; Streams; Trout; Vertebrata; Wildlife habitats; Europe; Spain; Salmonidae; Population number; Environmental factor; Ecology; Freshwater environment; Vertebrata; Salmo trutta; Feedback; Pisces; Morphology; Population recruitment; Stream; Population dynamics; Animal population; Population density; Ecological abundance
• ISSN: 0030-1299; 1600-0706
• DOI: 10.1111/j.0030-1299.2004.12989.x

The relative importance of endogenous feedback mechanism vs environmental factors in the dynamics of animal populations is a long-standing, but not fully resolved yet, issue in ecology. We have addressed this subject by examining the dynamics of a stream-resident population of Salmo trutta in a northwestern Spain stream. Recruitment was the major determinant of population size and the abundance of recruits resulted from a combination of regional and local environmental factors. Stream discharge in March determined the amount of stream area suitable for newly emerged trout ( r2=0.59-0.79%), that in turn determined the abundance of recruits at each site ( r2=0.51-0.77%). Stream discharge determines the overall strength of annual recruitment. Discharge, however, combines with stream morphology at the site scale to result in a site-specific area suitable for juveniles and, hence, site-specific recruitment. Thus, our study exemplifies how an environmentally driven animal population may persist on time with little or no operation of endogenous regulatory mechanisms.