Temporal changes in replicated experimental stream fish assemblages: predictable or not?

摘要: 1. Natural aquatic communities or habitats cannot be fully replicated in the wild, so little is known about how initially identical might change over time, extent to which observed changes community structure are caused by internal factors (such as interspecific interactions traits of individual species) versus external local abiotic disturbances invasions new species). 2. We quantified seven fish assemblages, that were similar possible, seminatural artificial streams a 388-day trial (May 1998 May 1999), and compared assemblages small pools natural stream during year. The experimental design excluded floods, droughts, immigration emigration. diverged significantly composition exhibited dissimilar trajectories multivariate species space. Divergence among increased from through August, but not thereafter. 3. Differences influenced differences developed year algae cover potential predation (due differential survival sunfish units). 4. In stream, changed more than those units, suggesting exacerbated temporal variation. 5. Our finding isolated most factors, would diverge time suggests lack strong internal, deterministic controls idiosyncratic stochastic components (chance encounters species; vagaries habitat) even within habitat patches can play an important role assemblage systems.