Both hydrology and physicochemistry influence diatom morphometry

Abstract

It has been shown that size of planktonic diatoms responds to changes in water chemistry, but little is known about the influence of different types of environmental factors upon benthic diatom size variation. Here we ask whether water chemistry or hydromorphological influences show a stronger effect on benthic diatom morphometry. 10,624 diatom valves / frustules were imaged, identified and measured from 48 samples across eight sites in the Ebro river basin obtained during ten years of biomonitoring work. We analysed how differences in surface-to-volume (S/V) ratio and other morphometric characteristics were related to spatial and temporal variability in environmental parameters. Our results show that both hydrological and physicochemical variables generated significant responses in interspecific and intraspecific morphometric variation. S/V ratio and transapical width showed the strongest responses, followed by (the predominantly used) cell volume. Freshwater benthic diatom morphology seems to respond to diverse environmental factors and could provide complementary ecological information to community composition.