Document Detail

Oxygen supply in aquatic ectotherms: partial pressure and solubility together explain biodiversity and size patterns.
MedLine Citation:
PMID:  21905423     Owner:  NLM     Status:  In-Process    
Aquatic ectotherms face the continuous challenge of capturing sufficient oxygen from their environment as the diffusion rate of oxygen in water is 3 x 10(5) times lower than in air. Despite the recognized importance of oxygen in shaping aquatic communities, consensus on what drives environmental oxygen availability is lacking. Physiologists emphasize oxygen partial pressure, while ecologists emphasize oxygen solubility, traditionally expressing oxygen in terms of concentrations. To resolve the question of whether partial pressure or solubility limits oxygen supply in nature, we return to first principles and derive an index of oxygen supply from Fick's classic first law of diffusion. This oxygen supply index (OSI) incorporates both partial pressure and solubility. Our OSI successfully explains published patterns in body size and species across environmental clines linked to differences in oxygen partial pressure (altitude, organic pollution) or oxygen solubility (temperature and salinity). Moreover, the OSI was more accurately and consistently related to these ecological patterns than other measures of oxygen (oxygen saturation, dissolved oxygen concentration, biochemical oxygen demand concentrations) and similarly outperformed temperature and altitude, which covaried with these environmental clines. Intriguingly, by incorporating gas diffusion rates, it becomes clear that actually more oxygen is available to an organism in warmer habitats where lower oxygen concentrations would suggest the reverse. Under our model, the observed reductions in aerobic performance in warmer habitats do not arise from lower oxygen concentrations, but instead through organismal oxygen demand exceeding supply. This reappraisal of how organismal thermal physiology and oxygen demands together shape aerobic performance in aquatic ectotherms and the new insight of how these components change with temperature have broad implications for predicting the responses of aquatic communities to ongoing global climate shifts.
Wilco C E P Verberk; David T Bilton; Piero Calosi; John I Spicer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ecology     Volume:  92     ISSN:  0012-9658     ISO Abbreviation:  Ecology     Publication Date:  2011 Aug 
Date Detail:
Created Date:  2011-09-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043541     Medline TA:  Ecology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1565-72     Citation Subset:  IM    
Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, University of Plymouth, Davy Building, Drake Circus, Plymouth PL48AA, United Kingdom.
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