Association between biogeographical factors and boreal lake fish assemblages

Five regions in insular Newfoundland Canada, comprising 152 lakes, were studied to identify associations between species composition (presence and absence), geographical location and environmental variables (pH, area, depth, alkalinity, secchi disc depth and shoreline development factor). Correspondence analysis and canonical variate analysis were used to distinguish regional patterns. Five biologically and environmentally distinct areas were identified. The degree of association between biological, environmental and geographical distances were contrasted using Mantel's test. Regional fish community structure was significantly correlated with large-scale geographical distance but not with environmental parameters or small scale distance. It was proposed that large scale processes such as post-glacial dispersion, climate and recent species introductions are important determinates in structuring regional fish assemblages. Differences in individual lake character were important determinates in intraregional variability in fish assemblage type. Sampling strategies for regional modelling and management are discussed.