Climate change-predicted shifts in the temperature regime of shallow groundwater produce rapid responses in ciliate communities
The ciliates living in a shallow groundwater system in southern Ontario, Canada were subjected to an in situ temperature manipulation over 14 months. Ciliates were collected from the bed surface of a small springbrook and from interstitial water collected at five depths beneath its surface. Mean tem...
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Published in | Global change biology Vol. 15; no. 10; pp. 2518 - 2538 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.10.2009
Wiley-Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | The ciliates living in a shallow groundwater system in southern Ontario, Canada were subjected to an in situ temperature manipulation over 14 months. Ciliates were collected from the bed surface of a small springbrook and from interstitial water collected at five depths beneath its surface. Mean temperature elevations established at each depth (−20, −40, −60, −80, and −100 cm) between the experiment's control and treatment blocks were 1.9, 3.5, 3.9, 3.8, and 3.6 °C, respectively, and were based on global warming projections for the region. In total, 160 species of ciliate belonging to 85 genera were identified. Overall, the treatment block had a higher density (6510±342 cells L−1; ±1 SE) than the control (5797±237 cells L−1), but densities were both vertically and longitudinally variable. Control densities decreased with depth, whereas treatment densities were more equal among depths. Total species richness showed no significant difference between blocks when combining all sampling dates and depths, although species composition changed. The ciliate community was dominated by small (15–50 μm), followed by medium (50–200 μm), and only a few large‐sized (>200 μm) species. Small ciliates contributed 82–97% of the total density. Small ciliates also contributed more to the treatment (94%) than the control block (88%). The most common ciliate feeding groups were bacterivores, omnivores, predators, and algae‐diatom feeders, with bacterivores being most dominant (83–99% of the total numbers collected). Ordination analyses revealed that ciliate distribution was strongly correlated with groundwater temperature, although dissolved oxygen level, concentrations of ammonia and nitrate, and depth also appeared to be influential. Peak densities of many species occurred in either the control or treatment blocks, but not in both. The benefits of using ciliates as a proxy for higher, much longer‐lived, eukaryotes in climate change studies are discussed. |
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Bibliography: | ArticleID:GCB1911 istex:2E81B279D4A7E5530BF698912505B450F9346DB1 ark:/67375/WNG-G9KDZLTQ-Z ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1354-1013 1365-2486 |
DOI: | 10.1111/j.1365-2486.2009.01911.x |