Morphological plastic responses to water depth and wave exposure in an aquatic plant (Myriophyllum spicatum)

Citation
Ja. Strand et Seb. Weisner, Morphological plastic responses to water depth and wave exposure in an aquatic plant (Myriophyllum spicatum), J ECOLOGY, 89(2), 2001, pp. 166-175
Citations number
54
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ECOLOGY
ISSN journal
0022-0477 → ACNP
Volume
89
Issue
2
Year of publication
2001
Pages
166 - 175
Database
ISI
SICI code
0022-0477(200104)89:2<166:MPRTWD>2.0.ZU;2-#
Abstract
1 We investigated morphological responses of the submerged macrophyte Myrio phyllum spicatum L. to water depth and wave exposure when grown in the same substrate at two sites in two eutrophic lakes. Periphyton production was 4 -8 times higher at sheltered than at wave-exposed sites and its influence w as further investigated in a glasshouse experiment. Morphological responses in both experiments were compared by allometric analyses, with shoot weigh t as covariate. 2 In the field study, plants shoots exhibited similar responses (increased plant height and branch length, and decreased branch number) to sheltered c onditions as to deep water. The partitioning between above- and below-groun d biomass however, differed, with below-ground decreasing with an increasin g water depth, but increasing or remaining unaffected at sheltered compared with exposed conditions. 3 In the glasshouse experiment, plant responses to water depth were similar to those in the field study. Furthermore, plant height increased when plan ts were overgrown with periphyton. 4 High production of periphytic algae at sheltered sites appears to cause l ight limitation of macrophytes. However, other factors such as nutrient upt ake also appears to determine morphological responses. At sheltered sites, where leaf nutrient uptake is reduced by abundant periphyton and thick boun dary layers, plants allocate more biomass to roots. At deep and wave-expose d sites, the absence of periphyton allows plants to take up nutrients throu gh their leaves and allocation of biomass to shoots increases photosynthesi s. 5 Overall, relative allocation to shoot and root biomass appears to be prim arily controlled by nutrient availability, whereas allocation of available shoot biomass to particular structures is controlled by light availability.