HR: 09:45h
AN: B51A-06    [Abstracts]
TI: Biotic and Abiotic Patch Dynamics in Two Macrophyte-Dominated Headwater Streams in Lowland UK
AU: * Cotton, J A
EM: j.cotton@qmul.ac.uk
AF: Department of Geography, Queen Mary University of London, Mile End Road, London, E1 4NS United Kingdom
AU: Bass, J
EM: jabb@ceh.ac.uk
AF: Centre for Ecology and Hydrology, Winfrith Technology Centre Winfrith Newburgh, Dorset, DT2 8ZD United Kingdom
AU: Wharton, G
EM: g.wharton@qmul.ac.uk
AF: Department of Geography, Queen Mary University of London, Mile End Road, London, E1 4NS United Kingdom
AU: Davies, A
EM: alice.davies@gmail.com
AF: Centre for Ecology and Hydrology, Winfrith Technology Centre Winfrith Newburgh, Dorset, DT2 8ZD United Kingdom
AB: UK groundwater-fed river systems have characteristically stable temperature and flow regimes with low turbidity. Unshaded shallow reaches support extensive growths of submerged macrophytes (e.g. aquatic Ranunculus spp.). The plant stands create habitat patch mosaics at the meso- and micro-habitat scale by modifying water velocity and depth and trapping fine sediment. The structure, dynamics and functioning of these discrete habitat patches has attracted comparatively few studies. This research investigated spatial and temporal variation in the biotic and abiotic components of such patches for two headwater streams. For both headwater streams, the habitat mosaic of patches at the reach scale incorporated vegetated patches (in-channel and marginal) and non-vegetated patches. However, the two reaches differed in terms of their in-channel and marginal vegetation growth patterns and species diversity and the numbers of dominant associated biota (Oligochaeta). Lower peak flows recorded at one site reduced disturbance and scour and promoted the growth of denser in-channel and marginal vegetation that enhanced sediment trapping and retention. The increased plant biomass caused heightened water levels during the summer stimulating further marginal vegetation growth and augmenting the sediment and nutrient retention of the marginal zone. Our results will be discussed in the context of the patch dynamics concept.
DE: 1800 HYDROLOGY
DE: 1824 Geomorphology (1625)
DE: 1851 Plant ecology
SC: Biogeosciences [B]
MN: 2005 Joint Assembly