Effects of macrophyte cutting on a whole lake ecosystem

Abstract

Macrophytes are of significant importance to aquatic ecosystems, generating primary production in nearshore environments and providing physical structure and habitat for organisms in the littoral zone of lakes. Macrophyte cutting is a common practice near human settlements, used to dampen the negative perceived effects they have on human activities. As such, understanding the impacts of vegetation cutting on both the lower and higher trophic levels can provide insight into impacts on the whole lake ecosystem. Impacts of macrophyte cutting on the whole-lake ecosystem were assessed at Lake 191 of the IISD-ELA, where 2 years of pre-experimental monitoring (1994 - 1995) were followed by 3 years of macrophyte cutting (1996-1998). After cutting occurred, macrophytes were allowed to re-establish and post-experimental monitoring occurred from 1999 until up to 2003. Results from this experiment showed decreased light penetration and decreased relative macrophyte biomass at 0.5m depth in 2000. Phytoplankton community composition became more variable, and biomass increased during macrophyte cutting. Daphnia pulex, Daphnia catawba, and Daphnia schoedleri collectively and Diaptomus oregonensis saw the greatest biomass changes within the zooplankton community. [...]