Project Title: Sediment Recycling: Marsh Renourishment Through Dredged Material Disposal
Principal Investigator(s): Lynn A. Leonard, Martin H. Posey, Troy D. Alphin, Lawrence B. Cahoon, Richard A. Laws

Accomplishments
Scheduled Tasks:

• Vascular plant surveys conducted in Januray, April, June and August 2001.
• Analyses of vascular plant data collected from May 2000 to June 2001.
• Winter water level surveys conducted from January 15th - February 15th, 2001.
• Soil geochemistry measurements collected in March, May, and July 2001.
• Preliminary analyses of soil geochemistry measurements.
• Conducted second and third "post sediment placement" sediment trap survey in March and July 2001.
• Benthic biomass samples collected monthly from January to July 2001.
• Analysis of benthic biomass samples collected from February to October 2000.
• Collection of microalgal taxonomy samples in February, April and June 2001.
• Preparation and processing of microalgal samples for taxonomy.
• Taxonomic identification of microalgae.
• Initiation of "pulsed sediment" experiments and subsequent monitoring of geochemistry and vascular plant biomass.
• Benthic infaunal cores were collected in May at all stations.

Progress on Tasks

• Data collection and analyses have generally proceeded on schedule.
• Initial results were presented at the Southeastern Sectional meeting of the Geological Society of America in Raleigh in April 2001. One of the graduate students funded by the project (A. Croft) gave the presentation entitled: "Effects of Dredged Material Disposal on Salt Marsh Processes".

Difficulties Encountered
Very few difficulties have been encountered during the last six-months of the project. Our biggest problem remains a changeover in project personnel that has hindered our progress in completing the microalgal taxonomy portion of the project. The boardwalks at the study site have begun to deteriorate thus limiting site accessibility for a shor time. We have (or are in the process) of repairing them. In addition, "Hogs Hair" filters were placed over low areas to reduce flow in areas subject to channelization.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period
We are on track to complete project objectives within the project period

Preliminary Results
Vascular Plant Data
Vascular plant data collection has continued on a bi-monthly schedule the last reporting period. We now have over one year of data. Preliminary plant density data were summarized in our last progress report. In general, stem densities in the deteriorated sites are lower than those in the non-deteriorated sites. There appears to be no relationship between stem density and treatment, however, these results have not yet been examine statistically. As expected, the number of live shoots per meter square decreased in the winter, but showed increases during the summer 2001 growing season at the non-deteriorated and the treated deteriorated sites (Figure 1). Vascular plant densities in the deteriorated controls did not show the biomass increases observed by their treated counterparts.

Water Level
Four RDS WL-40 water level recorders were placed in each of the four treatment sites for a one month sampling interval in January-February 2001. Each instrument measured and recorded water level once every six minutes. Raw data collected at each station is shown in Figure 2.

Sediment Geochemistry
Redox potentials have been measaured bi-monthly in each of the three treatment areas within each of the four sample plots since August 2000. Additional measurements have been collected in the control areas. Representative Eh profiles are shown in Figure 3. In general, the sediments have become more oxygenated at all sites over time. Sediment placement appears to have had the greatest impact near the surface in the deteriorated sites when compared to the control. These data are still being analyzed.

Sediment Traps
Sediment deposition was measured using petridish sediment traps in March and July, 2001. Accumaltion rates measured in October 2000 (reported previously) and March 2001 are shown in Figure 4. As reported in our most recent progress report, deposition in deteriorated sites following placement of dredged material continues to exceed deposition in non-deteriorated sites. These trends are consistent with those documented prior to sediment placement. In addition, sediment accumulation measured in the winter months are almost one order of magnitude lower than deposition rates measured in the fall. This seasonal pattern is consistent with deposition rates measured in other natural marsh systems.

Benthic Biomass
Benthic biomass samples have been taken monthly at all project sites since August 2000. Samples collected through October 2000 have been analyzed for benthic chlorophyll production. The remaining samples are either frozen or being prepared for analysis. The mean microalgal biomass measured at healthy sites in fall 2000 was 52.8 and 23.8 mg chla m^-2 for treated and control sites, respectively. For deteriorated sites in fall 2000, mean biomasses were 65.4 and 19.9 mg chla m^-2 for treated and control sites, respectively.

Microalgal taxonomy
All of the microalgal samples have been collected and are in various stages of preparation and anaysis. While identification of some samples has occurred, many samples have been prepared to the slide stage and are awaiting microscopic analysis. Other samples are still in the cleaning stage. Samples collected in June 2001 have not yet been processed.

Benthic invertebrates
Standard benthic benthic cores ~0.01 m² (10 cm diamter X 15 cm deep) were collected in May 2001. This sampling represents the nine month time period following sediment addition and follows the spring recruitment event. Two sets of paired cores were taken in each of the thick, mid, and thin addition treats in both the deteriorated and non-deteriorated plots. This was the second and final set of samples we proposed to collect in the original proposal. interesting patterns. Current efforts have been focused on processing the preliminary samples collected 6 weeks following sediment addition. Preliminary data analysis indicates that infaunal assemblages have been observed in all samples including those from the "thick" sediment additions (those expected to be most impacted by sediment placement). While we cannot at this time say what numerical impact sediment addition had on infauna, we do know sediment additions did not defaunate the underlying substrate.

Tasks and activities for next reporting period

Tasks for the next reporting period

• Continue bi-monthly vascular plant surveys and begin statistical analysis of results
• Continue bi-monthly geochemical measurements and statistical analysis of results
• Conduct additional "post sediment placement" sediment trap surveys
• Conduct textural and compositional analyses on sediment samples
• Continue to collect monthly benthic biomass samples
• Continue laboratory analysis of benthic biomass samples and conduct statistical analyses
• Complete microalgal sample preparation for year 1
• Continue microscopic analyses for microalgal taxonomy (i.e. species identification and counting)
• Initiate statistical analyses once all samples have been counted
• Continued processing and analysis of benthic infaunal samples with emphasis on "one-year" data.
• Once identifications of benthic infauna are complete, representative specimens will be sent for verification by an outside laboratory. This SOP maintains QA/QC and facilitates the creation of a current voucher collection.

Work plan to accomplish tasks

• Selected parameters (microalgal biomass, vascular plant attributes, sediment deposition, redox, benthic invertebrates ) will continue to be monitored according to the schedule of tasks provided. The project currently employs three graduate students and two undergraduate students who assist with data collection, sample preparation, and analyses. One additional graduate student, currently funded on a Teaching Assistantship by UNCW, also works 10-15 hours per week on the project.
• Present data at the Estuarine Research Federation Meeting in Tampa, FL (Nov. 3-8, 2001). We anticipate 2 separate presentations to be authored by graduated students.

Concerns or difficulties

• As always, our greatest concern is site security. Last year, we felt that the edges of the sites were somewhat compromised by non-project personnel who visited the site. We have taken steps to reduce visibility of the site to nearby boaters and also taken steps to mitigate any damage near the site caused by curious onlookers.
• We have also recruited a senior graduate student to assist with taxonomic identification of microalgae.

Expenditures
Expenditures were slightly less than anticipated for the work accomplished to date.