Lake Water Quality 2006 Report - Lakefield Herald

How Much Algae Sticks to Macrophytes in the Kawartha Lakes?by Wynona Marleau and Eric SagerIn the 2004 KLSA report, Bev Clark of the Ontario Ministry of the Environment veryeloquently described the alternative states in which shallow lake systems can exist –either a macrophyte (water weeds) dominated state such as we have in the Kawarthasor a phytoplankton (suspended algae) dominated state such as existed in Lake Erie inthe late 1970s. (Previous KLSA reports can be found at the KLSA page on the OliverCentre website: www.trentu.ca/olivercentre.) The latter state often gives the waterthe appearance of thick pea soup. Under high loadings of nutrients, mainlyphosphorus, the potential exists for lakes to shift from a clear-water, macrophytedominated state to one that is dominated by suspended algae. It is believed that oneof the precursors to this shift is the excessive growth of epiphyton (algae that isattached to submersed macrophytes) and metaphyton (algae that commonly originatesfrom true floating algal populations but gets tangled up among macrophytes and otherfloating debris). This excessive growth can lead to photo-inhibition of themacrophytes – they don’t get enough sunlight – which then allows phytoplankton, the45