Document Detail

Tracing Mississippi River influences in estuarine food webs of coastal Louisiana.
MedLine Citation:
PMID:  16041544     Owner:  NLM     Status:  MEDLINE    
The Breton Sound estuary in southern Louisiana receives large amounts of Mississippi River water via a controlled diversion structure at the upstream end of the estuary. We used stable isotopes to trace spatial and seasonal responses of the downstream food web to winter and spring introductions of river water. Analysis of delta13C, delta15N, and delta34S in the common local consumers such as grass shrimp (Palaemonetes sp.), barnacles (Balanus sp.), and small plankton-feeding fish (bay anchovies, Anchoa mitchilli) showed that the diversion was associated with two of the five major source regimes that were supporting food webs: a river regime near the diversion and a river-influenced productive marsh regime farther away from the diversion. Mixing models identified a third river-influenced source regime at the marine end of the estuary where major natural discharge from the Bird's Foot Delta wraps around into estuarine waters. The remaining two source regimes represented typical estuarine conditions: local freshwater sources especially from precipitation and a brackish source regime representing higher salinity marine influences. Overall, the Mississippi River diversion accounted for 75% of food web support in the upper estuary and 25% in the middle estuary, with influence strongest along known flow pathways and closest to the diversion. Isotopes also traced seasonal changes in river contributions, and indicated increased plant community productivity along the major flow path of diversion water. In the Breton Sound estuary, bottom-up forcing of food webs is strongly linked to river introductions and discharge, occurring in spatial and temporal patterns predictable from known river input regimes and known hydrologic circulation patterns.
Björn Wissel; Brian Fry
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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:  2005-07-22
Journal Detail:
Title:  Oecologia     Volume:  144     ISSN:  0029-8549     ISO Abbreviation:  Oecologia     Publication Date:  2005 Aug 
Date Detail:
Created Date:  2005-08-31     Completed Date:  2005-09-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0150372     Medline TA:  Oecologia     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  659-72     Citation Subset:  IM    
Department of Oceanography and Coastal Studies, Coastal Ecology Institute, Louisiana State University, 1209 Energy Coast and Environment Building, Baton Rouge, LA 70803, USA.
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MeSH Terms
Carbon Isotopes / metabolism*
Fishes / physiology
Food Chain*
Fresh Water
Nitrogen Isotopes / metabolism*
Palaemonidae / physiology
Sodium Chloride
Sulfur Isotopes / metabolism*
Thoracica / physiology
Time Factors
Reg. No./Substance:
0/Carbon Isotopes; 0/Nitrogen Isotopes; 0/Sulfur Isotopes; 7647-14-5/Sodium Chloride

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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