Document: DOR-3-75-10

Water lily (Nymphaea sp.) as a structuring agent of microhabitats in a shallow marsh.

BOORSE, D.F.*, T.WOLFE and CLINDSAY

Gordon College, Wenham MA 10984 USA ¹

Abstract:
Water quality patchiness may provide environmental heterogeneity and increase biodiversity in shallow marshes. We tested the hypothesis that large sections of water lily (Nymphaea sp.), including growing shoots and roots and associated clumps of detritus, acted as ecosystem engineers by determining the heterogeneity of water temperature and dissolved oxygen. Heterogeneity was defined as the mean of the absolute values of the differences between each measurement and its surrounding neighbors in a grid. After a reference measure of heterogenity was taken, water lily clumps were removed from one portion of a shallow marsh (removed) and moved to another (added). A third, unchanged area was used as a control. We predicted that mean difference between adjacent points would decrease as the habitat became more homogenous in the perturbed areas. After the perturbation, environmental heterogeneity decreased on the bottom in the removed portion than the control and added areas and increasedat the surface in the added area. Dissolved oxygen heterogeneity decreased at the water surface in control and removed areas and increased in sections with added vegetation while pattern was reversed on the marsh bottom. Vegetation pattern may affect microhabitat distribution indirectly through differences in water quality. An interaction between clumps of vegetation and the substrate may account for differences between the bottom and surface effects.

Keywords: dissolved oxygen, heterogeneity, microhabitat, Nymphaea, temperature

This abstract is being presented at: 4:15 PM in session:
Oral Session #65: Wetlands, Estuaries and Salt Marshes.