Diatom Community Response to Global Change
Abstract
Diatoms are ubiquitous components of marine and freshwater environments and are responsible for nearly a quarter of the world's primary production. These microscopic algae are excellent indicators of environmental change and are routinely used as indicators of water quality. Diatom frustules have also been used to infer past climate change. With anticipated increases in atmospheric CO2 and eutrophication, understanding the contribution by diatoms as sinks for carbon in the world's oceans and estuaries is crucial. Benthic diatoms are especially significant in this respect due to their interactions with both atmospheric and sedimentary carbon cycling. We investigated changes in marsh sediment diatom community structure in response to elevated atmospheric carbon dioxide and nitrogen input. Twenty plots of brackish marsh were enclosed in environmental chambers and exposed to two levels of atmospheric CO2 (ambient and elevated) crossed with a nitrogen-addition treatment (2 x 2 factorial) beginning in May 2006. DNA was extracted from sediment samples obtained from environmentally controlled marsh plots in June, 2008. Using diatom-specific primers, the diatom community was amplified by PCR and evaluated by denaturing gradient gel electrophoresis (DGGE). The diatom community composition was then compared across the four treatments (Amb, Amb+N, Elev, Elev+N) using multivariate statistical methods. Multidimensional scaling plots revealed clear grouping of samples according to treatment. A global analysis of similarity test was significant, as were all pairwise comparisons of treatments. The greatest changes in community structure occurred in the elevated CO2 group. In contrast, Amb+N was more similar to Elev+N, suggesting that nitrogen effects may mask elevated CO2 effects on diatom community structure in these plots.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFMOS33C1375H
- Keywords:
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- 0428 Carbon cycling (4806);
- 0469 Nitrogen cycling;
- 1630 Impacts of global change (1225);
- 4855 Phytoplankton