Periphyton Response to Nutrient Manipulation in 3 Lakes of Different Trophic Status: Effects on Density, Taxonomic Composition and Size Spectra
Abstract
Nutrient-diffusing substrata were used to examine nutrient limitation of periphyton communities in 3 Irish lakes that differ in periphyton productivity. Phosphorus addition treatments had significantly higher algal biovolume density than nitrogen addition or control. Canonical correspondence analysis using nominal variables to define treatments indicated both nutrient addition and lake productivity significantly affected taxonomic composition. The flora of the least productive lake was dominated by diatoms characteristic of low alkalinity and Bulbochaete. Phosphorous addition increased Bulbochaete in this lake, but increased Phormidium and Stigeoclonium in the two more productive lakes. Size spectra of algae were significantly affected by either nitrogen or phosphorus in the most productive lake because Stigeoclonium increased relative to smaller cyanobacteria and diatoms. Although nutrient addition increased large filamentous chlorophyte taxa in the two less productive lakes, it did not significantly affect size spectra. The results indicate that increased nutrient loading should increase periphyton area- specific biovolume, increase filamentous chlorophytes, and potentially shift size spectra to larger classes in lakes over a broad range of benthic productivities. The peak size class was smallest in the most productive lake suggesting that size spectra maybe more useful to indicate nutrient changes within a lake rather than define differences between lakes.
- Publication:
-
AGU Spring Meeting Abstracts
- Pub Date:
- May 2005
- Bibcode:
- 2005AGUSMNB32D..05D
- Keywords:
-
- 4239 Limnology