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U.S. GEOLOGICAL SURVEY
Open-File Report 02-394

NEAR FIELD RECEIVING WATER MONITORING OF BENTHIC COMMUNITY NEAR THE PALO ALTO WATER QUALITY CONTROL PLANT IN SOUTH SAN FRANCISCO BAY: FEBRUARY 1974 THROUGH DECEMBER 2000

Prepared in cooperation with the

CITY OF PALO ALTO, CALIFORNIA

By Janet K. Thompson, Francis Parchaso, and Michelle K. Shouse
 

ABSTRACT

Analyses of the benthic community structure over a 26-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinal clam Macoma balthica from the same area.  The community has shifted from being dominated by several opportunistic species to a community where the species are more similar in abundance, a pattern that could be indicative of a more stable community that is subjected to less stress.  In addition, two of the opportunistic species (Ampelisca abdita and Streblospio benedicti) that brood their young and live on the surface of the sediment in tubes have shown a continual decline in dominance coincident with the decline in metals.  Heteromastus filiformis, a subsurface polychaete worm that lives in the sediment, consumes sediment and organic particles residing in the sediment, and reproduces by laying their eggs on or in the sediment has shown a concurrent increase in dominance.   These changes in species dominance reflect a change in the community from one dominated by surface dwelling, brooding species to one with species with varying life history characteristics.  Analysis of the reproductive activity of Macoma balthica shows increases in reproductive activity concurrent with the decline in metal concentrations in the tissue of this organism.  Reproductive activity is presently stable with almost all animals reproducing during the two reproductive seasons (spring and fall) of most years.
 

CONTENTS

Abstract
Introduction
Previous monitoring of the benthic community in the near field receiving waters
Approach
Objectives
Study Site
Methods
Laboratory Analysis
Data Analysis: Methods
Results and Discussion
Benthic Community
Reproduction of Macoma balthica
Value of Long Term Monitoring
Bibliography
Appendix 1: Palo Alto Benthic Community   
Appendix 2: Palo Alto Macoma balthica Reproduction
Appendix 3: Examples of Environmental Data Used in Analysis of Benthic Community Data (plots taken from Shouse 2002)
 
 

This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader , it is available for free download from Adobe Systems Incorporated.

Download the Report (PDF, 0.79 MB)
 
Link to Appendix 1 Palo Alto Benthic Community (Excel File,  0.26 MB)  

Link to Appendix 2 Palo Alto Macoma balthica Reproduction   (Excel File, 0.04 MB)  

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Send questions or comments about this report to Janet K. Thompson (jthompso@usgs.gov) (650) 329-4364

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