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The Relationship of Macrophvtes With Epiphvton 

 Epiphytic algae growing in macrophyte beds often exhibit high 

 concentrations of biomass and are responsible for a significant 

 proportion of the primary production in a lake. Allen and Oceuski 

 (1981), for instance, determined that algal epiphytic production in 

 Lake Ohrid, Yugoslavia was higher than the production they 

 observed in littoral or pelagic algae. Cattaneo and Kalff (1980) 

 observed that the epiphytic algae in eutrophic portions of Lake 

 Memphremagog, Quebec fixed more carbon than macrophytes did 

 throughout the growing season. Fontaine and Ewel (1981) estimated 

 that macrophytes and their associated epiphytes were responsible 

 for 56% of the gross production in Little Lake Conway, Florida. 

 The question of macrophytes as a nutrient source for their 

 epiphytic algae has been a much-debated issue often referred to as 

 the "neutral substrate hypothesis" in the literature. Cattaneo and 

 Kalff (1979) observed no significant difference in epiphytic 

 production on Potamogeton richardsonii and artificial plants made of 

 plastic. They concluded that macrophytes functioned as neutral 

 support structures. Carignan and Kalff (1982) studied epiphytic 

 algae growing on fully 32p labelled Myriophyllum spicatum and 

 concluded that epiphytes derived only 3.4-9.0% of their P from the 

 labelled macrophytes, and that macrophytes were more important to 

 epiphytes for support than as a P source. Gough and Gough (1981) 

 took issue with Cattaneo and Kalff (1979), and cited Hutchinson's 

 (1975) statements that macrophytes release by-products of nutrient 

 assimilation, photosynthates and inorganic nutrients. They argued 



