Submerged macrophytes, zooplankton and the predominance of low‐ over high‐chlorophyll states in western boreal, shallow‐water wetlands

摘要: Summary 1. Shallow-water (<2 m deep) wetlands in northern Alberta's western boreal forest tend to have either extremely high-chlorophyll, pea-green water or that is low chlorophyll and clear. The relative importance of top-down processes (e.g. zooplankton grazing) compared with bottom-up nutrient limitation) for regulating the existence these alternate states has yet be explicitly investigated poorly studied waterbodies. 2. To assess relationship between chemical biological factors predominance low-chlorophyll over high-chlorophyll states, a survey 24 shallow-water Alberta was conducted summers 2001 2002. 3. In without fish, statistical analysis indicated high- sites could differentiated 82% accuracy based solely on whether submerged aquatic vegetation (SAV) coverage greater less than 25%. Further, high-SAV lakes communities dominated by large cladocerans were clear 96% time. 4. few supported stickleback populations, absent. However, development small cladocera (Bosmina) calanoid copepods fish-containing corresponded shift from states. 5. Results suggest fishless grazing large, SAV-associated promotes states. also suppression macroinvertebrate predators sticklebacks allowing Bosmina flourish may promote low-chlorophyll, clear-water conditions.