Potential effect of Myriophyllum spicatum on the primary production of phytoplankton

Allelopathic limitation of algal growth by macrophytes

“…Fitzgerald (1969), and found algal growth inhibition while nutrient competition seemed unlikely, but in the case of Fitzgerald (1969), bacteria-sized organisms were suggested to be the actual agents, while in the latter two papers light competition is not clearly excluded. Godmaire & Planas (1983) could exclude competition for light and nutrients, but found stimulation of algal growth by macrophytes. Their results and those of Fitzgerald (1969) point to the fact that allelopathic growth limitation of algae by macrophytes may be rather complex: some algal species are growth-limited, whereas others are not or may even be stimulated.…”

“…Although allelopathy was not mentioned, she did stress the 'beneficial effects' of C. vulgaris on water quality, which are lost when the species is replaced in the succession by other macrophytes. Godmaire & Planas (1983) did an enclosure experiment in which phytoplankton densities and rates of photosynthesis appeared to be enhanced especially in enclosures with M. spicatum but, to a lesser extent, also in those with a mixture of Sparganium sp. and Nuphar microphyllum (Pers.…”

“…Perhaps the concentration of growth mediators in the cultures was much higher than is normal in an aquatic system with macrophyte vegetation. To our knowledge, only Godmaire & Planas (1983) have investigated allelopathic activity in the field. In their enclosures with and without macrophytes in a lake, nutrient differences could not explain the stimulation of phytoplankton production in the enclosures with macrophytes (especially those with Myriophyllum spicatum L.).…”

ALLELOPATHIC GROWTH INHIBITION OF SELECTED PHYTOPLANKTON SPECIES BY SUBMERGED MACROPHYTES1

“…Only the experiments testing the effect of C. demersum on A. flos‐aquae were done with a P‐deficient nutrient medium but were included because A. flos‐aquae can maintain an exponential growth for 3 days without the addition of P if a maximum amount of P is stored (unpublished results; corresponding to the high storage capacity of this cyanobacterium for P measured by Uehlinger [1980]). In contrast to the studies of Godmaire and Planas (1983) and Hootsmans and Blindow (1994), we maintained a continuous influence of submerged macrophytes. The duration of the experiments was kept short to minimize the effect of bacteria that might affect the permeability of the dialysis membrane.…”

“…Anthoni et al 1980, Planas et al 1981, Wium‐Andersen et al 1982, 1983, Gross et al 1996), but this is no proof of their release and activity (Wium‐Andersen 1987). Most of the direct studies on allelopathic interactions between phytoplankton and submerged macrophytes (Hasler and Jones 1949, Fitzgerald 1969, Godmaire and Planas 1983, Forsberg et al 1990, Hootsmans and Blindow 1994, Jasser 1994, Gross et al 1996, Nakai et al 1999) suffer from technical problems. Often, competition for nutrients or light cannot be ruled out or a continuous effect of the released substances on phytoplankton could not be ensured.…”