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Growth enhancement of the macrophyte Ceratophyllum demersum in the presence of the snail Planorbis planorbis : the effect of grazing and chemical conditioning
Author(s) -
UNDERWOOD GRAHAM J.C.
Publication year - 1991
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1991.tb01738.x
Subject(s) - ceratophyllum demersum , macrophyte , snail , biology , grazing , periphyton , botany , ecology , aquatic plant , environmental science , algae
SUMMARY1 The effects of epiphyton grazing and nutrient recycling by the freshwater snail Planorbis planorbis on the growth of the macrophyte Ceratophyllum demersum were examined in laboratory experiments. 2 Ceratophyllum plants grown in the presence of snails, or in water chemically conditioned by snails, were significantly longer, had more healthy nodes of leaves, and more growing tips than Ceratophyllum plants grown in isolation. There were no significant differences between the growth of plants that were grazed by snails, and those plants which received water chemically conditioned by snails. 3 Adult P. planorbis released 3.74 × 10 −4 μg phosphate, 23.9 × 10 −4 μg nitrate, 4.38 × 10 −4 μg ammonia, and 0.79 × 10 −4 μg of urea mg −1 wet weight of snail h −1 . Measurements of these chemicals in the experimental systems suggested that ammonia was an important nutrient in stimulating the growth of Ceratophyllum.4 Removal of epiphyton by grazing snails significantly prolonged the life of individual Ceratophyllum leaves compared to ungrazed leaves.