Regeneration and colonization of aquatic plant fragments in relation to the disturbance frequency of their habitats

Abstract

The regeneration (regrowth into viable plants) and colonization (establish ment in the sediment) abilities of vegetative fragments of 16 aquatic plant species occurring in habitats with different disturbance frequencies were compared through a laboratory experiment. The hypothesis was that plants occurring in habitats frequently disturbed by floods should have higher regeneration and colonization abilities than plants in rarely disturbed habitats. Four types of fragments were collected from the plants and their regrowth and/or rooting into the sediment were recorded over 10 weeks. Numerous species exhibited a trade-off between their regeneration and coloni zation abilities (e.g. Sparganium emersum, Luronium natans), others presented frag ments with high abilities in both fi elds (e.g. Myriophyllum spicatum, Potamogeton coloratus), and others showed fragments with low abilities in both fields (e.g. Utricu laria vulgaris, Potamogeton lucens). The characteristics of two species (Potamogeton coloratus, Ceratophyllum demersum) did not fit in very well with the hypothesis, but this could be explained by their competitive abilities and ecological amplitude. Most species from habitats rarely disturbed by fl oods presented low regeneration and colo nization abilities. As predicted, species from habitats with high or intermediate dis turbance frequencies presented at least one of the two tactics, and this could be related to their adaptation strategies in withstanding disturbance events.

Fertile sediment and ammonium enrichment decrease the growth and biomechanical strength of submersed macrophyte Myriophyllum spicatum in an experiment

“…stress was vulnerable to be damaged by hydraulic force, resulting in allofragments of the plant, rather than autofragments. The allofragments generally have much lower survival potential than the plant autofragments in both field and experiments (Kimbel, 1982;Barrat-Segretain, 1996;Madsen, 1997;Barrat-Segretain et al, 1999), mainly due to their lower carbohydrate storage, which plays an important role in vegetative propagule performance (Spencer & Ksander, 1996;Werger & Huber, 2006). Therefore, our results imply that submersed vegetations grown in eutrophic lakes are prone to produce much more allofragments, indicating much lower survival potential in habitats with frequent disturbances.…”

Effects of water nutrients on regeneration capacity of submerged aquatic plant fragments

“…Interestingly, in four of the tested species here (M. spicatum, M. aquaticum, H. verticillata and C. demersum), regeneration started mostly by the production of new shoots, whereas in E. canadensis, E. nuttallii, E. najas and M. heterophyllum, predominantly a concurrent growth of new shoots and roots was documented right from the beginning of plant regeneration. This might cause higher colonization respectively uprooting rates in the field, but Barrat-Segretain et al (1998) and Barrat-Segretain and Bornette (2000) reported only a low percentage of colonization of regenerated fragments in E. canadensis. Fragments of other species were not found to root in the sediment (Barrat-Segretain and Bornette, 2000), but developed turions in autumn.…”

“…This might cause higher colonization respectively uprooting rates in the field, but Barrat-Segretain et al (1998) and Barrat-Segretain and Bornette (2000) reported only a low percentage of colonization of regenerated fragments in E. canadensis. Fragments of other species were not found to root in the sediment (Barrat-Segretain and Bornette, 2000), but developed turions in autumn.…”

Nature Conservation Against All? Aquatic Macrophyte De-Weeding – Cut or Conserve? A Stakeholder Analysis

“…appear to outcompete other aquatic macrophytes after mechanical clearing of water bodies (HowardWilliams et al 1996;Abernethy et al 1996). Second, many aquatic macrophytes proliferate by cut-off fragments (Barrat-Segretain & Bornette 2000;Mielecki & Pieczynska 2005), making it critical that the method of mechanical cutting not itself be counterproductive.…”