Substantial overnight reaeration by convective cooling discovered in pond ecosystems

ISBN:

0094-8276

Accession Number:

WOS:000383290300030

Other Number:

149

URL:

http://apps.webofknowledge.com/InboundService.do?Func=Frame&product=WOS&action=retrieve&mode=FullRecord&UT=WOS:000383290300030

Keywords:

AIR, AQUATIC ECOSYSTEMS, CARBON-DIOXIDE, co2, convection, dissolved oxygen, DISSOLVED-OXYGEN, ecosystem, gas exchange, GAS-EXCHANGE, Geosciences, Multidisciplinary, LAKES, METABOLISM, pond, reaeration, WATER, WIND-SPEED

Abstract:

Trends in freshwater dissolved oxygen (DO) reflect whole-ecosystem properties and influence organismal survival and behavior. Here we show that small ponds have unique oxygen dynamics that differ from larger lakes. We discovered that ponds undersaturated in DO experienced substantial increases in oxygen concentration overnight. Nighttime increases in DO occurred on 45% of the nights sampled and resulted in DO saturation increasing 12-fold (22% saturation) on average. Oxygen spikes were likely to occur when ponds became at least 1.8 degrees C warmer than the air and later in the season when oxygen levels were low (<31% saturation) and the air was warm (5.8 degrees C). We demonstrate that overnight increases in surface water DO resulted from atmospheric oxygen invasion as opposed to internal production. Convective cooling enhanced turbulence and air-water gas exchange, leading to intense bursts of oxygen invasion during nighttime hours. This mechanism has not been demonstrated before and has important implications for the biogeochemistry of these systems, as well as understanding how organisms survive in hypoxic small ponds.

Notes:

ISI Document Delivery No.: DV9VM<br/>Times Cited: 0<br/>Cited Reference Count: 45<br/>Holgerson, Meredith A. Zappa, Christopher J. Raymond, Peter A.<br/>Raymond, Peter/C-4087-2009<br/>Raymond, Peter/0000-0002-8564-7860<br/>National Science Foundation [DGE-1122492]; Yale University; Yale Institute for Biospheric Studies; Society for Freshwater Science; Friends of Chatham Waterways (Massachusetts); Village Garden Club of Dennis (Massachusetts)<br/>Data used are listed in Table S1 and Figures S1-S4. M.A.H. was supported by a National Science Foundation Graduate Research Fellowship (DGE-1122492) and Yale University. Research funding to M.A.H. came from Yale Institute for Biospheric Studies, Society for Freshwater Science, Friends of Chatham Waterways (Massachusetts), and the Village Garden Club of Dennis (Massachusetts). We thank D. Skelly and D. Post for helpful discussion, the Benoit lab for use of the YSI sonde, A. Subalusky for use of a YSI ProODO meter, and M. Duguid for use of waterproof cases. Thanks to the Yale Myers Forest team for lodging and use of study ponds. This manuscript was improved by comments from four anonymous reviewers.<br/><br/>3<br/>AMER GEOPHYSICAL UNION<br/>WASHINGTON<br/>GEOPHYS RES LETT