Influence of lake morphometry on the response of submerged macrophytes to sediment fertilization

In Lake Memphremagog (Quebec-Vermont), biomass increases were on average 2.1 times greater for fertilized plants than for controls. The extent of the growth response was greatest at 1.0 m depth sites. The smaller response at 2.5 m sites was further decreased as exposure to waves increased. The smaller response at 2.5 m (depth of maximum biomass) suggests that factors such as light limitation, length of the growing season, and littoral slope, but not sediment nutrient levels, limit submerged biomass there. The importance of physical factors appears to increase as biomass increases. "Overwintering' plants showed greater response to fertilization than those growing from seeds. Overall, extent of the growth response to sediment fertilization depends on the energy environment (depth, wave exposure, and slope) of the littoral. -from Authors