Document Detail

Direct effects of physical stress can be counteracted by indirect benefits: oyster growth on a tidal elevation gradient.
MedLine Citation:
PMID:  16249896     Owner:  NLM     Status:  MEDLINE    
The paradigmatic gradient for intertidal marine organisms of increasing physical stress from low to high elevation has long served as the basis for using direct effects of duration of water coverage to predict many biological patterns. Accordingly, changes in potential feeding time may predict the direction and magnitude of differences between elevations in individual growth rates of sessile marine invertebrates. Oysters (triploid Crassostrea ariakensis) experimentally introduced at intertidal (MLW+0.05 m) and subtidal (MLW-0.25 m) elevations in racks provided a test of the ability to use duration of water coverage to predict changes in growth. During early-to-mid winter, a depression of 38-47% in shell growth of intertidal oysters matched the 36% reduction in available feeding time relative to subtidal oysters. In late winter as solar heating of exposed oysters increased, growth differences of 52-55% departed only slightly from the predicted 39%. In spring, however, duration of water coverage failed to predict even the correct direction of growth change with elevation as intertidal oysters grew 34% faster despite 39% less feeding time. Intense seasonal development of shell fouling by other suspension feeders like ascidians, mussels, and barnacles on subtidal (94% incidence) but not on aerially exposed intertidal (21-38% incidence) oysters may explain why duration of water cover failed to predict spring growth differences. Less intense fouling develops on intertidal oysters due to the physiological stress of aerial exposure on settlers, especially during higher temperatures and longer solar exposures of spring. Fouling by suspension feeders is known to reduce growth of the host through localized competition for food and added energetic costs. Thus, in springtime, indirect effects of aerial exposure providing a partial refuge from biological enemies overwhelmed direct effects of reduced duration of water coverage to reverse the expected pattern of slower intertidal growth of a marine invertebrate.
Melanie J Bishop; Charles H Peterson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2005-10-25
Journal Detail:
Title:  Oecologia     Volume:  147     ISSN:  0029-8549     ISO Abbreviation:  Oecologia     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2006-02-28     Completed Date:  2006-05-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0150372     Medline TA:  Oecologia     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  426-33     Citation Subset:  IM    
Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC 28557, USA.
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MeSH Terms
Analysis of Variance
Ostreidae / growth & development*
Stress, Physiological*

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