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SCOPE OF SERVICES Background: Past studies of Lake Pontchartrain indicated a stressed benthic invertebrate community. Causes of stress were believed to be shell dredging and toxic compounds in the sediment. Recent studies indicate that recovery from shell dredging has occurred and that sediment contamination is not a major problem, but that saltwater intrusion and episodic hypoxia are serious problems. Unnaturally high salinity bottom water has entered Lake Pontchartrain since the Mississippi River Gulf Outlet was completed in 1963. This saline water produces stratification and bottom hypoxia. Low benthic invertebrate species diversity and the absence of large (> 20 mm) Rangia cuneata clams from a 100 mi 2 north of the IHNC documented in previous studies demonstrated a major impact. During the drought associated with the La Niña climate pattern from 1998 to 2002, benthic invertebrate species diversity and Rangia clam density decreased lake-wide from 374 to 4 clams/m 2 . This decrease in species diversity and in Rangia abundance throughout the lake may have been due to episodes of lake-wide low dissolved oxygen. Salinity has since returned to normal, but Rangia clams have not recovered. Additional studies are needed during 2004 and 2005 to obtain information needed to determine causal factors. These studies would provide information on the effects of salinity shifts on the overall benthic community; possible occurrence and effects of lake-wide hypoxia resulting from salinity stratification; the rate of benthic invertebrate recovery, especially Rangia clams; and Rangia growth rates. Goals: The long-term goal is to provide the knowledge needed to restore the benthic community. Cases of decline and recovery need to be determined and natural variation separated from human-induced changes. The working hypothesis is that saltwater intrusion is the primary cause of stress, but additional data on the extent and degree of stress and benefits of restoration are needed. Information on the effects of Mississippi River diversions is also needed. The primary goal for 2004-2005 studies is to determine the cause of Rangia decline and the rate of recovery. Objectives: (1) Determine the status of the bottom biota of Lake Pontchartrain by conducting lake-wide surveys of the distribution and abundance of benthic invertebrates during 2004 and 2005. (2) Relate 2004-2005 data to historic data to determine status and trends. This analysis will focus on the effects of hypoxia from salinity stratification, but will also include possible changes due to spillway openings/leakage, shell dredging, toxic chemicals, eutrophication, and shifts in overall ecosystem structure. (3) Determine changes in the population dynamics of Rangia clams due to drought driven salinity changes and recovery after a return to normal rainfall. (4) Based on benthic-invertebrate indicator species, evaluate the current area affected by hypoxia from salinity stratification in 2004 and 2005 (100 mi 2 in 1999). Project Methodology: Materials and methods employed in past UNO studies of Lake Pontchartrain benthic invertebrates will be used in this study. Sites on established transects will be sampled (three replicates) with a petite Ponar grab, sieved through a 0.6 mm screen bucket, preserved in formalin with rose Bengal stain in the field, and sorted and identified in the laboratory. Statistical analyses of data will include ANOVA and analyses in PRIMER (Plymouth Routines in Multivariate Ecological Research). All comparisons of data sets, 1
conclusions from data sets and hypothetical projections will be presented with appropriate statistical measures, based on significance within the 95 % confidence interval. Timeline and Milestones: During the 1 st Quarter (September through November), fall transects will be conducted, samples processed, and data entered. A paper will be presented at the ERCLA meeting. During the 2 nd Quarter (December through February), data entry will be completed, statistical analyses performed, results compared to historic data to determine trends and causal relationships, and a semiannual report will be prepared and submitted. Spring transects will be completed, samples processed, and data entered during the 3 rd Quarter (March through May). During the 4 th Quarter (June through August), data entry will be completed and statistical analyses performed. A final report will be submitted by the end of September 2005. Manuscripts for journal publication will be prepared and submitted. Deliverables: Deliverables will include semiannual reports. Results will be made available in the form of student theses, journal publications, meeting abstracts, poster and oral presentations at regional and national conferences, and other reports. Quality Control Measures: A QAPP is not required, but has been prepared for related work funded through EPA. All work will employ appropriate instrument maintenance and calibration, secure data management, trained personnel, control and replicate sampling and statistical testing. Results will be submitted for publication in peer-reviewed academic journals. Techniques for assessing success. All comparisons of data sets, conclusions from data sets and hypothetical projections will be presented with appropriate statistical measures, based on significance within the 95 % confidence interval. Personnel Qualifications: The University of New Orleans is an established research university with laboratories, equipment, BS, MS, and PhD programs, and other resources for conducting the proposed work. The P.I., Dr. Michael Poirrier, has thirty-three years of experience as a research faculty member at UNO. He has authored, or coauthored 13 book chapters, 47 journal articles, 28 technical reports, and 114 presentations at professional meetings, and served as major professor for 28 graduate students. He has conducted research on Lake Pontchartrain since 1969 and many of his publications pertain to Lake Pontchartrain biota and water quality. He has managed large externally funded research projects throughout his career. Dr. Poirrier participated in efforts to establish the Lake Pontchartrain Basin Foundation and served on committees to draft the Lake Pontchartrain Basin Comprehensive Management Plan. Elizabeth Spalding, a full time research associate, has a Masters degree in Biological Sciences and over seven years of experience in environmental science. Carol Franze, a research associate, will work half time on this project. She has an MA degree in Geography with a specialty in environmental analysis and has conducted research in the Pontchartrain Basin for over ten years. 2
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