Lake Pontchartrain Basin Research Program (PBRP) 2007 Annual Report
Southeastern Louisiana University Reporting Period: July 23, 2006 – July 22, 2007
1 TABLE OF CONTENTS
ADMINISTRATION ...... 3 LETTER FROM THE DIRECTOR ...... 4 GENERAL STATEMENT...... 6 SCIENCE ADVISORY COMMITTEE...... 6 MISSION STATEMENT ...... 8 TARGET AREAS ...... 8 INFORMATION TRANSFER AND OUTREACH COMPONENTS ...... 9 GRADUATE STUDENT COMPONENT ...... 10 PHASE I PROJECTS ...... 12 PHASE II/III PROJECTS...... 13 PHASE IV PROJECTS ...... 14 PHASE V PROJECTS...... 15 PHASE IV ANNUAL REPORTS...... 17
ESTABLISHMENT OF BASELINE CONCENTRATIONS AND ELUCIDATION OF ENVIRONMENTAL PROCESSES CONTROLLING THE BIOAVAILABILITY AND BIOACCUMULATION OF MERCURY AND 1 OTHER TOXIC METALS IN THE LAKE MAUREPAS BASIN. MARK W. HESTER , ASSAF A. 2 3 1 ABDELGHANI , KYLE R. PILLER , AND JONATHAN M. WILLIS ...... 17
VIABILITY OF MITIGATION IN THE LAKE MAUREPAS AND MANCHAC SWAMP REGION ROBERT 1 2 3 4 5 MOREAU , RICHARD CAMPANELLA , MICHAEL GREENE , RANDY MYERS , THAIS PERKINS , 6 7 GARY SHAFFER , FRED STOUDER ...... 23
HYDRAULIC CONDUCTIVITY AND VULNERABILITY TO XYLEM CAVITATION OF BALDCYPRESS (TAXODIUM DISTICHUM) ALONG A SALINITY GRADIENT AS INDICATORS FOR RESTORATION SUCCESS. VOLKER STILLER ...... 29
SALINITY AS A STRESSOR OF THE FRESHWATER TURTLE, TRACHEMYS SCRIPTA IN THE LAKE PONTCHARTRAIN BASIN. ROLDÁN VALVERDE ...... 35
GENETIC VARIATION BETWEEN LAKE PONTCHARTAIN AND MISSISSIPPI RIVER BASIN FISHES: PHASE II. KYLE R. PILLER ...... 41 EXPLORING YOUR ENVIRONMENT: EYE ON SOUTHEAST LOUISIANA PI: DR. DEBORAH DARDIS...45 PHASE V ANNUAL REPORTS ...... 48
DE-ENERGIZING HURRICANES WITH CYPRESS/TUPELO BUFFERS: A PLAN TO RESTORE THE REPRESSED SWAMPS OF THE LAKE PONTCHARTRAIN BASIN BY USING POINT AND NONPOINT FRESHWATER SOURCES. GARY P. SHAFFER1, HASSAN MASHRIQUI2, AND MOLLY MCGRAW3...... 48
MITIGATING THE SPREAD OF ZEBRA MUSSELS INTO WETLANDS FROM MISSISSIPPI RIVER DIVERSIONS. WILLIAM F. FONT...... 81
DEVELOPMENT OF AN INDEX OF BIOLOGICAL INTEGRITY FOR THE LAKE PONTCHARTRAIN BASIN WETLANDS JANICE BOSSART (PI) AND COLIN JACKSON (CO-PI)...... 87
DETERMINING THE POTENTIAL FOR ALGAL BLOOM IN LAKE MAUREPAS: EFFECTS OF CHANGING NUTRIENT LOAD FROM FRESHWATER DIVERSION AND CHANGES IN HUMAN POPULATION ...... 92
INFORMATION TRANSFER AND OUTREACH PROGRAM FOR THE LAKE PONTCHARTRAIN BASIN 1 2 3 RESEARCH PROGRAM. THAIS PERKINS , ROBERT MOREAU , TIFFANY MCFALLS , DENISE 4 ROUSSEAU-FORD ...... 97
2 Lake Pontchartrain Basin Research Program 2007 Annual Report
Administration
William N. Norton, Ph.D. Director, Lake Pontchartrain Basin Research Program Box 10736 Southeastern Louisiana University Hammond, LA 70402 Telephone: (985) 549-3740 FAX: (985) 549-3851 E-mail: [email protected]
Thais Perkins, M.S. Assistant Director Lake Pontchartrain Basin Research Program Box 10585 Southeastern Louisiana University Hammond, LA 70402 Telephone: (985) 549-2268 FAX: (985) 549-3851 E-mail: [email protected]
3 Letter from the Director
The 2007 year was a relatively quiet period for PBRP as compared to last year when the program experienced a comprehensive external review. PBRP did not have a new allocation to expand its research and education/outreach activities; however, there was a concerted effort to secure additional research funds. Most notably, a number of the program’s current PI’s collaborated with investigators from LSU, UNO, and Tulane to draft an extensive three million dollar multidisciplinary grant proposal for the Louisiana Board of Regents Post Katrina Scientific Initiatives Program. Although the project was not financially supported because of insufficient funds, the proposal was given a very favorable review by a panel of external evaluators. The theme of the proposed project, the conservation and sustainability of cypress ecosystems, will serve as a focal point of research for future proposals submitted to state and federal granting agencies by current and former PI’s of PBRP.
The Information Transfer and Outreach Program of PBRP was very successful during the past year in pursuing its goal of ensuring that the knowledge garnered in the program’s projects will be disseminated widely to technical professionals in the regulatory agencies and to community leaders, as well as to other important stakeholders and decision makers, the general public, and to the news media. Several Research Reports that focus on program supported research projects and their results, as well as a Pontchartrain Basin Update entitled “Understanding the Environmental Impacts of Cypress Mulch” were published and released. A pamphlet entitled “Notable Accomplishments of the Lake Pontchartrain Basin Research Program” was produced and distributed to the Louisiana Congressional Delegation. In addition, an exciting new supplement to this program is the “Swamps to Savannahs” presentation being offered to stakeholders around the basin as a face-to-face method of explaining the causes behind and solutions to Louisiana’s coastal loss. The seminar had been awarded extra funding by NOAA which is now nonforthcoming, and we are actively writing new proposals to continue this effort.
This annual report reflects the research activities of 11 PBRP based projects that have been funded at a total monetary value of approximately one million dollars. The diverse projects include an effort to determine whether genetic variation exists between Lake Maurepas and Mississippi River basin fishes, information that is critical for predicting the effects of fresh water diversion projects. Additional studies focus on the bioavailability and bioaccumulation of mercury and other toxic metals in the Lake Maurepas basin; the degree to which salinity induces stress on the endocrine system of an economically important species of turtle; the establishment of a physiological indicator of restoration success for baldcypress after its exposure to high salinity; and the determination of potential algal blooms in Lake Maurepas as a consequence of nutrient loading from freshwater diversion projects. PBRP is also funding research projects that are attempting to determine methods for mitigating the spread of zebra mussels into the wetlands from diversions of the Mississippi River; to develop an Index of Biological Integrity for Lake Pontchartrain Basin wetlands; and to design a plan to restore the repressed swamps of the Lake Pontchartrain Basin by using point and non- point freshwater sources.
4 PBRP supports essential education and outreach programs, as well as projects that concentrate on aspects of human behavior in the Lake Pontchartrain basin. One important PBRP funded project that pertains to human behavior is designed to develop a “white paper”, a how-to-manual, outreach workshops, and a web-site for Mitigation Banking in the Manchac Swamp. A critical aspect of the education and outreach programs is the hands-on interdisciplinary, educational experiences for both K-12 teachers and their students. The workshop oriented activities introduce participants to the ecology of the basin and attempt to instill in them an understanding of the important link between the region’s ecology and its cultural and economic vitality. Detailed accounts of the projects mentioned in this introduction can be found in the following report.
William N. Norton, Ph.D. Professor of Biological Sciences Director of the Lake Pontchartrain Basin Research Program
5
General Statement
The EPA supported Lake Pontchartrain Basin Research Program (PBRP) concentrates its resources and collective expertise on investigations of the Lake Pontchartrain Basin, an ecosystem that is recognized nationally for its economic and cultural significance. The Lake Pontchartrain Basin forms one of the largest and most important oligohaline coastal ecosystems in the United States. The mission of PBRP is to determine the ecological stresses, including those associated with human behavior, on the Lake Pontchartrain Basin ecosystem and to provide scientific information to decision makers and stakeholders on methods and policies to stabilize, sustain, and/or enhance its environmental and economic recovery in a manner that is harmonious with the Comprehensive Management Plan for the restoration of the Lake Pontchartrain Basin and the Louisiana Coastal Area. PBRP strongly encourages inter- institutional and interdisciplinary collaborations as mechanisms for an integrative approach to the investigation of the Lake Pontchartrain Basin. In addition to its support of projects designed to acquire information concerning the biotic and abiotic variables of the Pontchartrain Basin, PBRP is also committed to studies that focus on possible links between the social, cultural, political, and economic history of the region and the degradation of its ecosystem.
Science Advisory Committee
PBRP is guided by an external Science Advisory Committee (SAC) that consists of twelve individuals who represent academia, federal and state agencies, the local community, and the private sector. The members of SAC provide council and guidance to the Program Director and through a peer review system, critique submitted proposals for merit and compatibility with the Program Mission. SAC makes funding recommendations to the Program Director who then finalizes the ranking and dispersion of funds to the Principal Investigators (PI’s). Annual progress reports are submitted by the PI’s to the Director who then provides them to the members of SAC and to the EPA Project Officer for their review. SAC meets at approximately 6-month intervals to review submitted grant proposals for funding cycles and to review the progress of the projects. The members of the SAC, their profession affiliation, and respective area of expertise are listed below.
6 Members of Science Advisory Committee
Member Affiliation Expertise
Mr. Carleton Dufrechou Lake Pontchartrain Wetland restoration and Chairman of SAC Basin Foundation community involvement
Dr. Dale Manty EPA, Washington DC office Hazardous Substances
Dr. Robert Reimers Health Sciences Center Bioremediation Tulane University
Dr. Kenneth Teague U.S. EPA Region 6 Wetland restoration
Mr. Dan Llewellyn Louisiana Department of Wetland ecology Natural Resources
Dr. Len Bahr Coastal Activities Division Policy/Environmental Office of Governor of Louisiana regulations
Dr. Fred Kopfler U.S. EPA Region 4 Coastal restoration EPA Gulf of Mexico Program
Mr. Gordon Austin Sewerage & Water Board of Treatment of sewage and New Orleans waste water
Dr. Mike Livingston Sobran Environmental Consultants Environmental toxicology
Dr. Marilyn Kilgen Head of Biology Department Environmental Nicholls State University microbiology
Dr. David Constant Professor and Assistant Director Environmental engineering EPA HSRC, LSU
Bill Hawkins Exec. Director GCRL Environmental toxicology Univ. of Southern Mississippi
7 Mission Statement
The mission of PBRP is to determine the ecological stresses, including those associated with human behavior, on the Lake Pontchartrain Basin ecosystem and to provide scientific information to decision makers and stakeholders on methods and policies to stabilize, sustain, and/or enhance its environmental and economic recovery in a manner that is harmonious with the Comprehensive Management Plan for the restoration of the Lake Pontchartrain Basin and the Louisiana Coastal Area.
Target Areas
PBRP has established central themes or target areas for investigators to address. Funded projects in Phase V (the most recent phase) were designed to:
1. Identify the various environmental factors, including biotic and abiotic stressors that both positively and negatively impact the Lake Pontchartrain Basin and determine the extent to which they affect that ecosystem.
2. Determine the social, economic and governmental factors that must be considered in order to achieve environmental recovery and sustainability of the Lake Pontchartrain Basin ecosystem.
3. Employ established and effective environmental models to determine the impact of specific variables of the ecosystem. Of particular interest are models that may be used to investigate various parameters associated with proposed fresh water diversion projects, such as the analysis of water quality, the deposition of particles, and flow rates. Principal Investigators who wish to design projects that focus on environmental models should contact the Program Director prior to the drafting of their proposal to be linked to appropriate operational environmental management models.
4. Design projects that will provide pertinent information regarding freshwater diversion programs. Examples of relevant topics include the proliferation of algal blooms, pollutant loading, nutrient loading, the impact of toxins such as benzene, heavy metals, herbicides, and pesticides, an analysis of the socioeconomic impacts, and the effect on threatened and endangered species.
5. Address factors that are specifically associated with Katrina/Rita-induced demographic changes, especially as they pertain to the North shore of Lake Pontchartrain. Examples include environmental stresses induced by significant increases in population, pollutant loading, land use, and wetland loss. Of particular importance are the effects of development and urbanization in the Pontchartrain watershed on the water quality in the estuaries.
8 Information Transfer and Outreach Components
All proposals submitted to PBRP must have a Information Transfer and Outreach section. Funded PI’s are expected to address their progress in this effort throughout the project. Information Transfer is of paramount importance since state and federal agencies are searching for the most scientifically sound methods of managing the complex ecosystems of southeastern Louisiana. This fact is especially critical in the wake of Hurricanes Katrina and Rita. The ultimate recipients of Information Transfer and Outreach documents will be stakeholders and policy makers who have the authority or resources to promote restoration. The Principal Investigators are consistently reminded that policy makers and stakeholders can not make meaningful and appropriate decisions on the management of our wetlands, including flood protection, unless they are provided meaningful results of research and insightful analysis and recommendations from the individuals who investigate the Pontchartrain ecosystem.
9
Graduate Student Component
An important goal of PBRP is to train a new generation of young scientists who will continue to address significant environmental problems. Southeastern is a master’s level I comprehensive regional university according to the Carnegie classification of universities and colleges. The names of the graduate students who are participating in PBRP funded research projects, their respective Major Professor (Principal Investigator), and the level of their support are presented below.
Phase I Projects
Graduate Student Major Professor (PI) Level of Support
Megan Collins William Font $16,000 David Fox Phil Stouffer $16,000 Ellen Geho Paul Keddy $16,000 Brett Henry Ann Cheek $16,000 Demetra Kandalepas Paul Keddy $16,000 Timothy Menzel Paul Keddy $16,000 Sarah Temple William Font $16,000
Phase II/III/IV Projects
Graduate Student Major Professor (PI) Level of Support
Lisa Cordes Kyle Piller $16,000 Todd Hymel Brian Crother $16,000 Jessica Klopf Penny Shockett $16,000 Eddie Koch Gary Shaffer $16,000 Leonard McCauley Gary Shaffer $16,000 Erica Perrer Penny Shockett $16,000 Joe Ramspott Brian Crother $16,000 Roxanne Rudowicz Colin Jackson $16,000 Tiffany Schriever Brian Crother $16,000 Jack Siegrist Paul Keddy $16,000 Spencer Varnado Gary Shaffer $16,000 Jason Zoller Gary Shaffer $16,000
10 Phase V Projects
Graduate Student Major Professor (PI) Level of Support
Colby Morgan Bill Font $16,000 Chris Lundberg Gary Shaffer $16,000
Total Number of Graduate Students in Phases I-V ……………...…… 21 Total Amount of Financial Support for Graduate Students ………….. $338,000
11 Phase I Projects
Principal Investigators, Their Profession Affiliation, and Area of Expertise
Ann Cheek (SLU), Endocrinology/Physiology Debbie Dardis (SLU), Science Education William Font (SLU), Parasitology Mark Hester (UNO), Plant Physiology Paul Keddy (SLU), Wetland Ecology Rob Moreau (SLU), Environmental Studies Gary Shaffer (SLU), Wetland Ecology Phil Stouffer (LSU), Ornithology
Research Associates, Their Professional Affiliation, and Area of Expertise
Dan Campbell (SLU), Wetland Ecology Jonathan Willis (UNO), Environmental Toxicology Thais Perkins (SLU), Wetland Restoration
Project Titles, Principal Investigators, and Project Budgets
Project Title Principal Investigator Budget Effects of Multiple Stressors on Marshes Paul Keddy, PI $95,000 and Swamps
Ecosystem Health and Restoration Needs Gary Shaffer, PI $197,701 for Swamps
Constraints on Plant Establishment and Mark Hester, PI $187,011 Community Composition
Vegetation and Bird Communities Phil Stouffer, PI $124,519
The Fish Parasite Community William Font, PI $131,960
Effects of Contaminants Ann Cheek, PI $121,425
Teacher Workshops and In-Service Training Debbie Dardis, PI $97,196
Public Outreach and Environmental History Rob Moreau, PI $23,412
12 Phase II/III Projects
Principal Investigators, Their Profession Affiliation, and Area of Expertise
Brian Crother (SLU), Herpetology Debbie Dardis (SLU), Science Education Cliff Fontenot (SLU), Herpetology Maury Howard (SLU), Environmental Chemistry Sam Hyde (SLU), History Paul Keddy (SLU), Wetland Ecology Colin Jackson (SLU), Microbiology Jay Johnson (SLU), Environmental Economics Kyle Piller (SLU), Ichthyology Rob Moreau (SLU), Environmental Studies Gary Shaffer (SLU), Wetland Ecology Phil Stouffer (Louisiana State University), Ornithology Penny Shockett (SLU), Immunology
Research Associates, Their Professional Affiliation, and Area of Expertise
Tiffany McFalls (SLU), Wetland Ecology William Wood (SLU), Wetland Ecology Jason Zoller (LSU), Ornithology
Project Titles, Principal Investigators, and Project Budgets Project Title Principal Investigator Budget Contingent Valuation of the Western Lake Jay Johnson $30,000 Pontchartrain Basin Ecosystem
Amphibian and Reptile Monitoring in the Brian Crother $96,000 Pontchartrain-Maurepas Region
Restoring Biological Diversity to Wetlands of Paul Keddy $260,000 the Greater Manchac Region
The Historical Transformation of the Manchac Basin Sam Hyde $65,000 Ecosystem: Ecological Degradation at the Hands of Man
Organic Matter Processing in Western Lake Colin Jackson $221,000 Pontchartrain Basin Wetlands
A Whole-System Approach for Restoring the Gary Shaffer $340,000 Wetlands of the Western Lake Pontchartrain Basin
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Outreach Component for Southeastern Louisiana Rob Moreau $54,000 University Western Lake Pontchartrain Basin Research Program
Western Lake Pontchartrain Basin Research Debbie Dardis $155,000 Program: Education Outreach Program
Are Polycyclic Aromatic Hydrocarbons Stressors for Penny Shockett $100,000 Lymphocyte Development or Activation in Frog Populations in Bayou Trepagnier?
Genetic Variation Between Lake Maurepas and Kyle Piller $160,000 Mississippi River Basin Fishes
Heavy Metal Contaminants: A Study Investigating the Maury Howard $75,000 Occurrence, Distribution, and Species of Trace Metal Inputs to Western Lake Pontchartrain
Phase IV Projects
Principal Investigators, Their Profession Affiliation, and Area of Expertise
Kyle Piller (SLU), Fish Genetics Assaf Abdelghani (Tulane), Mark Hester (UL Lafayette), Wetland Ecology Jonathan Willis (UNO), Wetland Ecology Robert Moreau (SLU), Environmental Studies Michael Greene (SLU), Biology and Science Education Richard Campanella (Tulane), Geography/ GIS Volker Stiller (SLU), Plant Physiology Roldan Valverde (SLU), Animal Physiology Debbie Dardis (SLU), Science Education
Research Associates, Their Professional Affiliation, and Area of Expertise
Rebecca Johansen (SLU), Fish Genetics William Wood (SLU), Wetland Ecology Jonathan Willis (UNO), Wetland Ecology
14 Project Titles, Principal Investigators, and Project Budgets Project Title Principal Investigators Budget Establishment of Baseline Concentrations and Elucidation Jonathan Willis Kyle Piller, $68,000 of Environmental Processes Controlling the Bioavailability Assaf Abdelghani, Mark and Bioaccumulation of Mercury and Other Toxic Metals Hester, in the Lake Maurepas Basin. Development of White Paper, How-To Manual, Outreach Robert Moreau, Michael $77,148 Workshops and Website for Mitigation Banking in Greene, Richard Manchac Swamp Campanella Hydraulic Conductivity and Vulnerability to Xylem Volker Stiller $77,500 Cavitation of Baldcypress (Taxodium distichum) Along a Salinity Gradient as Indicators for Restoration Success. Salinity as a Stressor of the Freshwater Turtle (Trachemys Roldan Valverde $37,500 scripta) in the Lake Pontchartrain Basin Genetic variation between Lake Maurepas and Mississippi Kyle Piller $70,000 River Basin Fishes Western Lake Pontchartrain Basin Research Program: Debbie Dardis $15,000 Education Outreach Program
Phase V Projects
Principal Investigators, Their Profession Affiliation, and Area of Expertise
Gary Shaffer (SLU), Wetland Ecology Molly McGraw (SLU), Geology Hassan Mashriqui (LSU), Ecological Modeling William Font (SLU, Parisitology Mike Fitzsimmons (LSU) Janice Bossart (SLU), Animal Behavior Colin Jackson (U of Mississippi), Microbiology Assaf Abdelghani (Tulane), Philip Voegel (SLU), Chemistry Pinckney, Sophia Passey (UT Arlington), Robert Moreau (SLU), Environmental Studies Thais Perkins (SLU), Science Communication Denise Rousseau-Ford (LSU), Science Communication
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Project Titles, Principal Investigators, and Project Budgets Principal Project Title Investigators Budget De-energizing Storms with Cypress/Tupelo Buffers: A Gary Shaffer, Molly $136,318 Plan to Restore the Repressed Swamps of the lake McGraw, Hassan Pontchartrain Basin by Using Point and Non-point Mashriqui Freshwater Sources
Mitigating the Spread of Zebra Mussels into Wetlands William Font, Mike $88,492 from Mississippi River Diversions Fitzsimmons
Development of an Index of Biological Integrity for Lake Janice Bossart, Colin $145,817 Pontchartrain Basin Wetlands Jackson, Assaf Abdelghani Determining the Potential for Algal Bloom in Lake Philip Voegel, James $87,512 Maurepas: Effects of Changing Nutrient Load from Pinckney, Sophia Freshwater Diversion and Changes in Human Population Passey
Information Transfer and Outreach for the Lake Robert Moreau, $72,179 Pontchartrain Basin Research Program Thais Perkins, Denise Rousseau- Ford
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Phase IV Annual Reports
Establishment of baseline concentrations and elucidation of environmental processes controlling the bioavailability and bioaccumulation of mercury and other toxic metals in the Lake Maurepas Basin. Mark W. Hester1, Assaf A. Abdelghani2, Kyle R. Piller3, and Jonathan M. Willis1
1Department of Biology 2Department of Env. Health Sci. 3Department of Biol.Sci. University of LA, Lafayette Tulane University Southeastern LA Univ. Lafayette, LA 70504 New Orleans, LA 70148 Hammond, LA 70403
Abstract
Mercury is a toxicant of global concern due the tendency of some of its chemical species to be highly bioavailable and neurotoxic (e.g., methyl mercury chloride) and the word-wide distribution of mercury in even pristine settings due to substantial atmospheric transport. As the methylation of mercury is primarily accomplished by sulfate-reducing bacteria prevalent in wetlands and aquatic sediments, these habitat types require the most intense scrutiny to ensure that human and ecosystem health are not subject to unanticipated risks. The ongoing research described below summarizes the approach and current findings of research designed to investigate vegetative and abiotic factors relevant to mercury bioaccumulation in the Lake Maurepas system.
Primary Objectives
The primary objective of this research is to assess the concentration and bioaccumulation of trace and toxic metals, particularly mercury, in the wetlands of the Lake Maurepas Basin. To best meet this overarching objective, a series of specific sub-objectives have been generated and studies explicitly designed to address these sub-objectives initiated.
1) To determine the current concentrations of toxic metals, particularly mercury, in the soils, interstitial waters, and vegetation of the wetlands of Lake Maurepas.
2) To evaluate the potential transfer of mercury between native sediments, local vegetation, and a common invertebrate.
3) To assess interspecific differences demonstrated by tidal freshwater wetland vegetation in the bioaccumulation and translocation of inorganic mercury.
Results to Date
The greenhouse mesocosm study investigating the transformations of mercury in an oligohaline wetland soil and its uptake by various freshwater wetland plant species and a common freshwater invertebrate is currently underway. Because of damage to the aquatic toxicology facility at Tulane University the study is being conducted at the University of
17 Louisiana at Lafayette’s Center for Engineering and Environmental Technology. Also, two changes in the vegetative species being assessed have been to allow the results to be more relevant to the Lake Maurepas wetlands and the local food webs. First, Spartina patens, which was originally suggested because of its generally wide distribution in olighaline and brackish environments, was dropped in favor of Polygonum punctatum. Recent research has shown that S. patens is unlikely to expand into the Lake Maurepas wetlands, whereas P. punctatum is widespread through the Lake Maurepas wetlands. Also, Peltandra virginica was dropped in favor of Pontedaria cordata, which is generally considered a much more important food source for local wildlife.
All plots have been established for the field study and sampling for the Spring 2007 and Summer 2007 periods completed. All field sites appear generally comparable regarding spring of 2007 and summer 2007 pore water pH (range of 5.5 to 6.5) and Spring 2007 soil redox status (130 to 270 mV). Greater reduction of sediments was seen at Reserve Canal, Tobe Canal, and Turtle Cove sites in Summer of 2007 (- 40 to 45 mV). It should be noted that all soil redox status values were above levels generally associated with sulfate reduction being the dominant microbial metabolic process. This is in agreement with pore water sulfide levels, which were generally below 1 ppm for all sites, and the anecdotal observation that all field plots lacked surficial water at the time of sampling indicating that some re-oxygenation of the soil was likely occurring. Interestingly, all sites with the exception of Turtle Cove were similar in spring and summer of 2007 regarding soil moisture content, soil organic matter and soil pore water salinity. The Turtle Cove site was noted to have lower soil organic matter (~20% versus 40% to 80%) likely related to its geographic location in a more brackish zone. Currently analysis of the methyl mercury content of surficial (top 2 cm) wetland sediment and vegetative tissue is underway. Sediment pore water dissolved total mercury concentrations are representative of uncontaminated wetland environments (Fig. 1). Characterization of surficial wetland soils indicate that sites within the Lake Maurepas wetlands are within the range of typical unpolluted wetlands in regards to total mercury content (Fig. 2 top panel). Also, the aboveground and belowground vegetative tissue concentrations of mercury appear to be within the range typical for an unpolluted site (Fig 2 bottom panel). Other toxic metals (Cd, Cr, Pb, Ni, Cu, and Zn) also appear to occur in pore water, sediment, and plant tissue at trace levels typical of an unpolluted wetland. Structural equation models are currently being generated to investigate relationships among and between total mercury concentrations in various environmental compartments (e.g., sediment, sediment pore water, belowground plant tissue, and aboveground plant tissue) and environmental factors (e.g., soil redox status, pore water pH, pore water total sulfides, pore water chloride). All field and mesocosm studies are anticipated to be completed by late winter of 2008.
Technology Transfer
Project Goal
The intent of these studies to both provide a baseline assessment of current levels of toxic elements, particularly mercury, in the Lake Maurepas wetlands and assess how shifts in various abiotic factors may alter the availability of these toxic components. The focus on mercury results from its high potential bioavailability and toxicity as well as its tendency to accumulate in wetland systems that have do not have a direct industrial input of this contaminant. Assessment of current levels of these contaminants and their seasonal variation, if any, will
18 allow for local resource managers to make informed decisions regarding restoration activities (e.g., spoil bank gapping, river diversions, etc) that could increase the conductivity between the fringing wetlands and the waters of Lake Maurepas. This research has implications beyond the local environment as the elucidation of mercury cycling in wetland soils and vegetation, bioaccumulation risks and possibilities for sequestration can provide insight for scientists managing similar environments in the southeastern United States.
Sustainability Questions
1) What are the current concentrations of methyl and total mercury in the Lake Maurepas wetland soils and interstitial water, and how do they vary seasonally?
2) Do the dominant herbaceous plant species and a common invertebrate of the Lake Maurepas wetlands bioaccumulate mercury?
3) How do edaphic conditions and the potential alteration thereof affect mercury cycling?
Hypotheses
1) Although the concentration of either mercury or methyl mercury in the Lake Maurepas wetlands is currently unknown, methyl mercury concentration is anticipated to vary seasonally with the greatest concentrations in the summer due to microbial activity.
2) It is anticipated that all of the plant species tested, as well as the common invertebrate, will bioaccumulate mercury to some extent.
3) Anoxic soil conditions with moderate levels of available sulfate and labile carbon are expected to lead to maximum methyl mercury production, with increased levels of nitrate tending to ameliorate this production.
Management Recommendations
At its conclusion this research will enable resource managers to make informed decisions about the risk of introducing toxic contaminants from the wetlands surrounding Lake Maurepas into its open waters. Also, local resource users will be provided with a solid database to better understand the potential risks, if any, to the local habitats. The understanding of factors controlling bioaccumulation of toxic elements by plant and invertebrate species will be useful to local and regional scientists, resource managers, and resource users. Preliminary data indicate toxic element concentrations in various environmental compartments are within typical ranges for natural systems, however, no conclusions should be made until all of the data have been analyzed and presented.
Affected Parties
Agencies Louisiana Department of Natural Resources Louisiana Department of Environmental Quality Environmental Protection Agency
Geographies Stakeholders St. John the Baptist Hunters Tangipahoa Fishermen/Shrimpers Livingston Recreational Users
Summary Statement
19 The series of studies comprising this research effort are intended to provide local stakeholders and resource managers information as to the current levels of toxic metal contaminants in the Lake Maurepas wetlands and bioaccumulation risk, thereby allowing for optimal management of this resource. Preliminary data indicate that levels of trace and toxic elements in the Lake Maurepas system are typical of natural wetland environments and do not pose unusual risk. However, no conclusions should be taken from this work until all of the analyses are completed, particularly the determination of methyl mercury in various environmental compartments and the mesocosm evaluations of bioaccumulation.
20 80 Spring 2007
70
60
50
40
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20 Total Pore Water Hg (ng/L)
10
0 Amite River Blind River Joyce WMA Reserve Tobe Canal Turtle Cove Canal Field Sites 80 Summer 2007
70
60
50
40
30
20 Total Pore Water Hg (ng/L)
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0 Amite River Blind River Joyce WMA Reserve Tobe Canal Turtle Cove Canal Field Sites Fig. 1. Effect of site on total pore water Hg (ng/L ; mean +/- se)
21 450 Summer 2007 400
350
300
250
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150
Total Sediment Total Hg (ng/g) 100
50
0 Amite River Blind River Joyce WMA Reserve Tobe Canal Turtle Cove Canal Field Sites 200 Summer 2007 180 Aboveground
160 Belowground
140
120
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Total Plant tissue Hg (ng/g) 40
20
0 Amite River Blind River Joyce WMA Reserve Tobe Canal Turtle Cove Canal Field Sites Fig. 2. Top Panel: Effect of site on summer 2007 total sediment Hg content (ng/g; mean +/- se). Bottom Panel: Effect of site on summer 2007 aboveground and belowground plant tissue concentration (ng/g; mean +/- se). 22
Viability of Mitigation in the Lake Maurepas and Manchac Swamp Region Robert Moreau1, Richard Campanella2, Michael Greene3, Randy Myers4, Thais Perkins5, Gary Shaffer6, Fred Stouder7
1PI, Manager, Southeastern’s Turtle Cove Environmental Research Station 2Assistant Director, Environmental Analysis and Remote Sensing/GIS Specialist, Center for BioEnvironmental Research, Tulane University 3Biologist on Staff and Education/Outreach Coordinator (Turtle Cove ERS) 4Biologist Manager of WMA’s, Louisiana Department of Wildlife and Fisheries 5Assistant Director, PBRP 6, Biology Department, Southeastern Louisiana University 7Marsh Restoration Coordinator (Turtle Cove ERS)
Proposed Study Area (what’s in a name?)
Ponchatoula Swamp Joyce Swamp Maurepas Swamp Manchac Swamp Blind River Ruddock Swamp Swamp Reserve Swamp
10/5/2007 5
Abstract The purpose of this three-year project is to study the viability of wetland mitigation in the area generally know as the Manchac/Maurepas Swamp. Major deliverables are to develop: (1) a detailed “Whitepaper” that designates potentially viable mitigation sites within the study area using a combination of LIDAR data (a new application here), potential sources of freshwater inputs from sewage effluent sites, suitability and land ownership maps, and other GIS overlay information., as well as an overview of protocols on how to establish, promote, and operate a mitigation bank in the area (geared to state agency representatives); (2) a “How- To” manual designed to communicate this information to the public (geared towards land owners and developers); (3) a workshop in the area to explain the concept to interested members of the public; and (4) a Web Site devoted to mitigation banking in the study site. This three-year project is funded at of $77,147.
23 Primary Objectives Primary objectives of the project are to create a series of tools that will aid all stakeholders in the mitigation arena in the identification of viable mitigation sites in the Manchac/Maurepas Swamp. Specific objectives include: (1) Development of a White Paper that is designed to provide mitigation information to local, state and federal agency representatives involved in mitigation in the area. The primary focus of the white paper includes the development of a new technique to map the viability of potentially suitable mitigation sites within the study area. The new technique to be tested is based on LIDAR data on tree canopy height, as well as information and maps on attributes such as: ownership of large tracts of lands (shown as private vs. public); suitability of sites for mitigation (based on LIDAR produced tree canopy data, fresh water inputs, elevation, and salinity data, among others); and other geographic and demographic data. (2) Development of a How-To Manual that is designed to provide the information noted above to land owners, developers, and the general public at large. (3) A workshop at the end of the process, and at a location near the study site, that will promote these and other materials to the various stakeholders addressed in the study (agency representatives, land owners, developers, non profit groups, the general public, etc.). (4) Development of a website that will serve as a clearinghouse of information for the above mentioned deliverables.
Results and Discussion The project was started in February 2006 (a delayed start due to the storms of 2005), and pertinent information learned thus far has been helpful in fine-tuning the remainder of the study. For instance, it was determined early on that viable mitigation sites in the study area would be few and far between due to low elevations and high salinity, but that potential sources of fresh water from multiple (small) sewage effluent sites that surround the study site above the two foot contour could be a compensating factor. Therefore these sources and their locations will be placed in the GIS model along with the LIDAR data on tree canopy height, land ownership and other relevant variables.
Key findings and results learned to date that have helped establish, fine-tune, and in some cases re-direct the research include: (1) The study site was defined as the two-foot contour around the Manchac/Maurepas swamps, and consists of a terrestrial area of approximately 460.5 sq miles (294,735 acres). Establishment of the two foot contour for the study site is appropriate because it divides the land neatly between undeveloped marsh and swamp habitat from more developed agricultural sites. The designation is also cadastrally appropriate; (2) Growth rates along the north shore in St. Tammany parish are nearly five times that of the national average, and habitat developed there is mainly marsh, wetland forest, and scrubbrush wetland (making the Manchac/Maurepas Swamp a natural area for comparable mitigation); (3) Growth rates in St. Tammany Parish are even higher since the storms of 2005 (rates of 40% growth). The population growth rates (seen as a proxy for development) on the north shore, particularly in St. Tammany Parish, points toward the need to have comparable
24 mitigation sites available---the Manchac/Maurepas Swamp is appropriate from that standpoint (if of course appropriate and suitable mitigation sites can be identified); (4) Land ownership designation in the study site is currently broken down into the two major categories of private lands (69%) and public lands (31%), and that ratio is continually changing right now in a positive direction for public lands (i.e., LDWF is in the process of purchasing land for inclusion in their Wildlife Management Areas there); (5) Ownership of land has a significant impact on mitigation potential. In general, public lands may be more difficult to designate as mitigation sites, mainly because such lands are already assigned some sort of management status (and may not be appropriate to “upgrade” into mitigation, since they are already being conserved or preserved in one way or another); (6) Regarding public land ownership, one very interesting development is the capability of public agencies (such as LDWF) to purchase land for public use with mitigation funds, thereby having the land also be “preserved” as a mitigation site thru the mitigation process (e.g., the purchased land, if in good shape environmentally, may provide a large mitigation ratio and may be used to offset development---so it is purchased as an already completed mitigation project, but is in much better value environmentally than traditional degraded land that has to be mitigated); (7) Public lands may also be more difficult to put into mitigation than private lands because of political issues involving price and fund allocation within the agency, as well as the competition that then results between private and public land owners in the mitigation arena. However, the value of public lands in the mitigation arena should not be discarded, but rather reviewed on a case-by-case basis; (8) Impediments to mitigation in the study site include: appropriate land suitability (areas where trees have a chance to grow); land owner ignorance about mitigation; complexity of mitigation guidelines; access to appropriate sites; and, perhaps most importantly, competing land owner choices (other programs besides mitigation); (9) Private landowners have many other government-sponsored programs that compete with mitigation. The list includes, among others, the Conservation Reserve Program (CRP); Wildlife Habitat Improvement Program (WHIP); forthcoming Carbon Sequestration Programs; and others. Most of these programs are sponsored through annual Farm Bill Policy programming, and do not allow for “double dipping” (having land placed under more than one designated category which might include mitigation). Another competing issue to mitigation is land owners’ right and availability to use their land on the “open market” for things such as leasing (hunting and fishing or mineral rights), outright sale of land, and other market-based types of activities, although some of these may allow for simultaneous mitigation as well; (10) There are currently only two mitigation sites in the Maurepas Swamp part of the study site, and they average about $10,000 per acre. One is a private bank that entails 1,000 acres of cypress replanting; the other is a WLF site purchased in an already “preserved” (mitigated) state of about 2,500 acres. On the Manchac side, there is one site managed by Southeastern but with very limited success rates for cypress replanting (due to high salinities and low elevations) and limited acres (180) in play. The lack of more sites suggests that a major impediment to mitigation there is site unsuitability (high salinities/low elevations) and the low probability for long term success of cypress plantings. (11) However, preliminary results from recent related research (reference J. Day and G. Shaffer paper) has shown that proper amounts of waste water effluent delivered to areas--even those areas of low(er) elevation and high(er) salinities--can aid in development and growth of
25 young cypress trees. This has prompted the researchers to include those areas as data points in the GIS mapping exercise.
Results of LIDAR Mapping For wetlands mitigation banking to succeed, managers need an accurate assessment of the health and viability of existing swamp forest resources. Those that are most viable offer the best opportunities for protection/preservation and restoration through mitigation banking. While project researchers have detailed forest inventory data for selected sample points in the Maurepas Swamp, comprehensive coverage for data on tree height is needed as well.
These data may be attainable through LIDAR (Light Detection and Ranging) data. Funded by the Federal Emergency Management Agency (FEMA) and the state, a mapping contractor captured LIDAR data for the most flood-prone parishes of Louisiana during 1999- 2003, including the Maurepas Swamp, to produce topographic maps with unprecedented accuracy. This particular LIDAR sensor, mounted in an aircraft flying at 8,000 feet altitude, emits 15,000-30,000 laser pulses per second aimed at the target site. The exact time and direction of each pulse are recorded as it leaves the sensor and as it returns after reflecting off surface features. Because the speed of light is constant, the system is able to compute the distance to and from the target, and because a Global Positioning System (GPS) is integrated with the sensor, exact geodetic coordinates are associated with each pulse.
From these raw data, analysts are later able to compute the precise longitude, latitude, and elevation of millions of points scattered irregularly upon the target area. Not just the earth’s surface but buildings, cars, most vegetation, and other features are also captured, and must be removed through a post-processing algorithm to map the underlying topographic elevation. A continuous surface is then interpolated from the points, from which are extracted contours at intervals as detailed as 6 inches, or digital elevation models with five-meter- resolution pixels.
As part of this mitigation banking project, we sought to determine the extent to which the "raw" LIDAR data (including tree height) could be used to create accurate and detailed maps of tree canopy height, which would thereby provide information as to where healthy stands of trees are (a component of the equation showing where viable sites for mitigation might be). To do this, we performed the following steps:
Step 1: Obtained forest inventory GPS sampling points (for which measurements on BA06/HA, BA/625m2 of cypress, tupelo, other species, and total stem were measured in the field); Step 2: Processed and mosaicked the raw LIDAR for the portion of the Maurepas swamp sampled with the above data points; Step 3: Built a GIS in which the above datasets and others were spatially referenced and overlaid accurately; Step 4: Wrote an Arc Macro Language (AML) script to compute the following: a. Calculated for a 5x5 pixel (25mx25m) kernel surrounding each of the sample sites the following: mean ground elevation, standard deviation of ground elevation, mean raw LIDAR height including elevation and vegetation in 1999-2000, standard deviation of LIDAR height
26 including elevation and vegetation in 1999-2000, mean 1999-2000 vegetation height with elevation removed, and standard deviation of 1999-2000 vegetation height with elevation removed; b. Computed 8 additional 5x5 kernels immediately adjacent to the center kernel, one to the NW, NC, NE, EC, SE, SC, SW, and WC. Within each, the above summary statistics (average and standard deviation) of tree height and base elevation were dumped out; c. The LIDAR measurements were appended to the original GPS data/forestry measurement spreadsheet and send back to Dr. Gar Shaffer for analysis; Step 5: Forthcoming analysis of the statistical relationships between the field data and the LIDAR data will inform us as to what extent we may be able to use the LIDAR dataset (available for the entire basin) as a valuable base map for directing mitigation banking decisions. Preliminary information on this aspect so far showed that a factor analysis had very high loadings of LIDAR variables and structural variables such as stem density and basal area. LIDAR plus structural data produced almost perfect separation of the three habitat types (degraded, relict, and potentially sustainable). Dr. Gary Shaffer is now working with Richard Campanella on further refining the algorithms and statistical inferences needed to maximize accuracy and use of this data.
Future Plans During the next year, the researchers will do the following: (1) Mesh and refine LIDAR/Ground Truthing relationships in a way that provides the most accurate and comprehensive measurements of tree canopy and ground elevations (Campanella and Shaffer); (2) Incorporate above relationships into overall GIS model, which will also be refined by obtaining up-to-date land ownership data, potential waste water effluent sources, and data from other variables that will be used in the model (Campanella, Myers, Perkins, Shaffer and Stouder); (3) Complete drafts of White Paper, How-To Manual and Mitigation Website (Moreau, Campanella, Perkins and Myers); (4) Design and conduct mitigation workshop in local area, including compilations of participant information (Moreau, Perkins and Myers) (5) Compile lists of designated agencies/entities/persons for distribution of the materials and for inclusion on website as contacts.
Information Transfer This project is, in itself, an exercise in Information Transfer. Information learned in the research of mitigation banking potential in Manchac Swamp will be disseminated to a wide group of decision makers, including: natural resource agency personnel; land owners; financial interest entities; community and environmental groups; local politicians; and other interested members of the public. This information will be transferred through a variety of media incorporated in the deliverables of the project, including: journals (for the white paper); a website; workshops; and of course the availability of a hard copy and internet available “how- to manual.”
27 This project is important for policy makers because it will give those involved in our region accurate and up-to-date information about where viable mitigation sites might exist as development further encroaches on the north shore communities. Local, available, and suitable sites for mitigation is of paramount importance right now in our region as development for both housing and infrastructure (including levees for hurricane protection) continues to increase. It is now widely known that the U.S. Army Corps of Engineers (USACE) is now actively pursing mitigation sites as they begin planning the development of enhanced levee systems throughout southeastern Louisiana—many of these new levee sites will require mitigation. The stakeholders in this arena are many and include the afore-mentioned. Agencies that will be impacted with this information include LDWF, LDEQ, LDNR, USACE, NRCS, and USEPA, among others. Besides land owners and developers, various public interest groups (hunters, fishermen, wildlife enthusiasts, etc.) need to be aware of appropriate mitigation alternatives. All parishes within the Lake Pontchartrain Basin will be impacted and thus will benefit from this information. It is hoped that this research will aid all stakeholders in the region in obtaining the latest knowledge and information about the viability of mitigation activities in this area.
28 Hydraulic conductivity and vulnerability to xylem cavitation of Baldcypress (Taxodium distichum) along a salinity gradient as indicators for restoration success. Volker Stiller
Abstract In the past, considerable efforts have been undertaken to restore Baldcypress trees around Lake Pontchartrain. Vast amounts of cypress trees have been planted with varying rates of success. The project aims at supporting future restoration efforts of Baldcypress by investigating the role of plant hydraulics on restoration success. The specific goals of the study are a) to evaluate the amount of “drought” stress young Baldcypress trees are subjected to, due to increased salinity in their habitat, and b) to evaluate if the xylem of Baldcypress possesses the inherent plasticity to acclimate to increased salinity. The answers to these two, very basic, questions are currently unknown and will provide an invaluable tool in the decision process when and where to plant cypress trees.
Primary Objective The project will achieve its goals by conducting 4 simple experiments. The first experiment will evaluate the vulnerability of Baldcypress to xylem dysfunction by establishing so-called “vulnerability curves”. These curves show the percent loss of hydraulic conductivity in relation to negative xylem pressure and are a fundamental parameter to understand a species ability to grow in a specific environment. In two field experiments, the in situ the hydraulic conductivity and the amount of xylem cavitation in Baldcypress will be measured along a salinity gradient. In addition to these field studies, a greenhouse study will be conducted, in which the ability of cypress trees to acclimate to increased salinity will be evaluated. Baldcypress will be grown in the SLU greenhouse and the salinity of the irrigation water will be gradually increased from 0ppt to 5ppt. Transpiration and growth measurements throughout the experiment will detect possible acclimation to salinity.
Results for 2007 Activities in the fall of 2006 and spring/summer of 2007 focused on the greenhouse experiment. Approximately 50 one-year old, bare rooted seedlings were grown under ambient conditions in the greenhouse of Southeastern Louisiana University. After plants were established, half of the trees were irrigated twice daily with salt water; the other half (control) was watered with fresh water twice a day. The concentration of the salt solution was gradually raised over an 8-week period from 2ppt to 8ppt and was then kept constant at 8ppt for the remainder of the experiment (10 weeks). Throughout the growing season, transpiration rates, stomatal conductances, and relative diameter growth rates were monitored. At the end of the growing season, plants were harvested and vulnerability curves and wood densities were measured on current year stem segments.
29 Salinity reduced transpiration rates (Figure 1) and stomatal conductances (not shown) approximately by half (E = 2.5±0.8 and 4.7±1.0 mmol s-1 s-2; gS = 215±64 and 436±127 mmol s-1 s-2 for salt and control plants, respectively. Mean ± SD, n = 5). Reduced transpiration rates were mirrored by lower relative diameter growth rates (Figure 2) in salt treated plants (RGR= 0.09±0.03 mm/mm and 0.15±0.07 mm/mm for salt and control plants, respectively. Mean ± SD, n = 9).At the end of the growing season (late October to early November), 6-10 treatment and control plants were harvested and xylem vulnerability to cavitation was measured. Vulnerability curves (Figure 3) showed that the P50 of salt treated plants was significantly more negative (–2.57 MPa) compared to control plants (–2.25 MPa; n=9, p<0.001, F-test). Wood density (Figure 4) of salt treated plants was greater (0.33±0.02 g/cm3) compared to control plants (0.29±0.02 g/cm3; n=9, p<0.05). Although P50, RGR and wood density were measured on the same plants, wood density was correlated only with RGR (p<0.05) but not with P50 (Figure 5). 6.0
5.0
4.0
3.0
2.0
1.0 transpiration rate (mmol s-1 m-2 0.0 salt treatment control
Figure 1 Transpiration rate of 1-yr old bald cypress (n=5). Error bars represent 1SD
30
0.250
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0.150
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0.050 relative diameter growth rate (mm/mm) 0.000 salt control
Figure 2 Relative diameter growth rate of 1-yr old bald cypress from Figure 3 during 80d of salt treatment (8ppt). Error bars represent 1SD.
31 Taxodium distichum 2006 100 salt treatment 90 control 80 70 60 50 PLC 40 30 20 10 0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0
Ψxylem [MPa]
Figure 3 Vulnerability curves of 1-yr old stem segments. A Weibull function was fitted to the pooled data for each treatment (n=9). P50 = –2.57 MPa and –2.25 MPa for salt treated and control plants, respectively.
0.400
)
3 0.350
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wood densitywood (g/cm 0.250
0.200 salt control
Figure 4 Wood density of 1-yr old bald cypress from Figure 3 after 80d of salt treatment (8ppt). Error bars represent 1SD.
32
0.3 -1.00
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0.2 -3.00 Weibull P50 0.200 0.250 0.300 0.350 0.400
wood density (g/cm3) 0.15
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0.05 control salt 0 0.200 0.250 0.300 0.350 0.400 0.450 0.500 wood density (g/cm3)
Figure 5 Relative diameter growth rate and P50 (insert) from individual Weibull fits of 1-yr old bald cypress from Figure 3 as a function of wood density
During spring and summer of 2007, the greenhouse experiment was repeated in order to obtain a more robust data set. In addition, a drought stress treatment was implemented. Drought stressed seedlings were irrigated once per week with fresh water. As in the previous year, transpiration and growth rates were monitored and leaf and soil water potentials were measured. Preliminary data analysis indicates that drought stress mimics elevated salinity. At the end of the growing season, vulnerability curves will be measured.
Conclusion and Future Plans Our results show that 1-yr old Baldcypress seedlings are able to acclimate to increased soil salinity by: • reducing transpiration and growth rates, • increasing wood density and • reducing xylem cavitation vulnerability.
Drought stress seems to have the same effects on seedlings than salinity, which would make “stress hardening techniques” in nurseries much easier to implement as not salt would have to be used. However, whether the stress-induced acclimation translates into greater survival rates under field conditions needs to be evaluated in an upcoming field study.
33 Information Transfer The overall goal of the present study aims at supporting future restoration efforts of Baldcypress by investigating the role of plant hydraulics on restoration success. The specific goals of the study are a) to evaluate the amount of “drought” stress young Baldcypress trees are subjected to, due to increased salinity in their habitat, and b) to evaluate if the xylem of Baldcypress possesses the inherent plasticity to acclimate to increased salinity. The answers to these two, very basic, questions are currently unknown and will provide an invaluable tool in the decision process when and where to plant cypress trees.
The anticipated results from this study not only provide new insights into the limitations of water transport in Baldcypress, but also lead to a better understanding of the hydraulic constraints on restoration efforts. These results should be of interest for all groups and management agencies that are involved with the restoration of Baldcypress.
Furthermore, results from the greenhouse “acclimation study” can help develop possible preconditioning treatments for cypress trees in nurseries. Such preconditioning treatments could lead to hardier cypress trees that would be better suited to withstand the transplantation shock when planted in brackish or saline habitats and could be a valuable tool for nurseries that provide the plant material for restoration projects.
34 Salinity as a stressor of the freshwater turtle, Trachemys scripta in the Lake Pontchartrain Basin. Roldán Valverde
Abstract The Lake Pontchartrain System, constituted by Lakes Pontchartrain and Maurepas, are under increasing influence of salt water intrusion from the Gulf of Mexico. This influx of saltwater is thought to place stressful physiological constrains on the biota of the basin, particularly of freshwater species. Research efforts during the first year of the grant have focused on solving logistic aspects of field and lab work, such as developing an effective method to trap turtles and establishing the best set up to expose turtles to various salinities in the lab and testing them for stress. During the second year we focused on trapping turtles and conducting the salinity exposure experiments of wild caught turtles. Currently, laboratory salinity exposure trials have been completed for lab raised turtles. Trapping and salinity exposure trials continue with wild turtles. We are also focused on validating the corticosterone assay kit to measure stress hormones in our turtles.
Primary Objective(s)
The primary objective of this study is to demonstrate that the red-eared slider freshwater turtle is a good physiological model to serve as an environmental sentinel with regard to salinity in the Lake Pontchartrain Basin. This objective will be accomplished by pursuing the specific objectives listed below.
1. To test the hypothesis that red-eared slider turtles living at higher salinity exhibit a hyperactive adrenal gland. This hypothesis is being tested using animals captured in the field. A hyperactive adrenal gland would suggest that the turtle lives in a stressful environment.
2. To test the hypothesis that increases in environmental salinity induce an endocrine stress response in the red-eared slider turtle. This hypothesis is being tested in the laboratory using captive-raised animals.
3. To test the hypothesis that the red-eared slider turtle is more abundant in less saline environments within the Lake Pontchartrain Basin. This hypothesis predicts that red-eared slider is more abundant in a Lake Maurepas’ tributary where salinity is lowest within the Lake Pontchartrain Basin.
Results
1. To test the hypothesis that red-eared slider turtles living at higher salinity exhibit a hyperactive adrenal gland.
During the past year we have dedicated our efforts to identify specific optimal locations on the Lake Pontchartrain basin to trap turtles (Table 1). The main criterion leading our efforts is to
35 find locations that represent the salinity gradient in the Basin where turtles have been observed. The original locations proposed were Natalbany River, near the area where the Tickfaw River drains into North Lake Maurepas (low salinity), Stinking Bayou on Pass Manchac, and Cane Bayou adjacent to Big Branch National Wildlife Refuge. These locations were selected after consulting with colleagues that have several years of experience working in the basin. In every case we were assured that turtles were present in these sites in meaningful numbers. However, after conducting several sampling trips we noticed that the number of turtles was not as abundant as we were led to believe. In addition, we noticed a significant decrease in the number of turtles since these animals became active in March-April of 2006, particularly in the Tickfaw River and in Cane Bayou areas. Also, we have not seen any turtles in Stinking Bayou since the beginning of the field sampling component in the Spring of 2006. Last Fall we decided to change our efforts to the West side of Lake Maurepas, close to the Hope Canal Diversion Project site. We tried without success various locations on the Blind River (Table 1). This summer we decided to deploy different traps (hoop nets and commercial traps) at a new site using chicken legs as bait. This site is located by the boat shed where the turtle cove boat is kept. This area and the new bait yielded excellent results as we were able to trap 10 turtles over night.
Table 1. Location of the various sampling sites in the Lake Pontchartrain Basin.
Site Abbreviation Latitude (N) Longitude (W) Blind River A BR A 30° 13.131 90° 38.388 Blind River B BR B 30° 12.796 90° 37.242 Blind River C BR C 30° 12.821 90° 38.126 Blind River D BR D 30° 14.063 90° 38.573 Tickfaw River A TF A 30° 21.978 90° 29.468 Tickfaw River B TF B 30° 21.960 90° 29.693 Tickfaw River C TF C 30° 22.507 90° 29.949 Stinking Bayou 1 SB 1 30° 18.997 90° 18.752 Stinking Bayou 2 SB 2 30°18.768 90° 19.277
As seen in Table 2, the salinity in the Blind river area is similar to that of the Tickfaw River. This similarity in salinity and the higher number of turtles observed in the Blind River sites suggests that salinity is not reason for the low number of basking turtles observed in the Tickfaw River sites. However, recent data indicate that Tickfaw River area was significantly impacted by floods during Hurricane Katrina (Boundy and Kennedy, 2006). The floods occurred during the Hurricane had the effect of flushing turtles and many other organisms from the Tickfaw River area where we set up the traps at the beginning of the study. Because even the food turtles consume (mostly fish) were also washed away, there appears to be little for these animals to recolonize this area (Jeff Boundy, pers. comm). The process of resettlement is expected to take some time due to the slow recovery of the system and trophic chains in the area.
36 Table 2. Mean temperature and salinity (± standard deviation) measured at the different sampling sites in the Lake Pontchartrain Basin.
Site Temperature (°C) Salinity (‰) TF A 28.10 ± 0.57 1.35 ± 0.07 TF C 28.05 ± 0.64 1.00 ± 0.00 STB 2 28.57 ± 0.21 7.13 ± 0.81 BR A 28.1 ± 0.42 0.95 ± 0.21 BR B 29.30 1.1 BR C 27.55 ± 0.92 1.25 ± 0.07 BR D 28.7 0.7
2. To test the hypothesis that increases in environmental salinity induce an endocrine stress response in the red-eared slider turtle. Our efforts to address this objective have focused on obtaining blood from small experimental turtles. Although the PI has extensive experience obtaining blood samples from large sea turtles, small turtles present a challenge, particularly in light of the intensive sampling regimes that must be followed with a large number of small animals in the lab. Indeed, a single experiment with a control and three different salinities involves 48 turtles. During an experiment, a large proportion of these animals must be sampled within a minute or two. Thus, every experiment requires several individuals to handle turtles, samples, records, etc. During this past year we have succeeded at developing a reliable method to collect blood from the turtles. This breakthrough has allowed us to complete all our exposure experiment with lab-raised turtles. These experiments included testing the effect of various exposure times (12 days, 1 month, 3 months) on the stress system of the turtles to determine which exposure time will show a physiological response. We are currently in the process of validating the corticosterone assay kit to measure stress hormone in all samples collected. Our goal is to have the assay validated and all samples analyzed by the end of the Fall semester.
3. To test the hypothesis that the red-eared slider turtle is more abundant in less saline environments within the Lake Pontchartrain Basin. We had originally planned to address this objective by deploying several basking platforms at key locations representing the salinity gradient of the Lake Pontchartrain basin. However, after testing several platforms at the three originally proposed sites we decided to desist from our efforts. The main reason is that turtles did not use the platforms as actively as we expected. Thus, the platforms appear inadequate to undertake this part of the study. In addition, the weak construction of the platforms (Styrofoam) led the structures to suffer damages, mostly caused by wind. Instead of this approach we have recently developed a new method to generate a relative index of abundance. The methodology consists of determining a trapping per unit time effort. This will be based on the number of traps deployed and the number of turtles trapped at every site with regard to trapping time (i.e., how long the traps were set to capture a given number of turtles). The idea is that the number of turtles trapped per unit of time and number of traps is a direct function of turtle abundance, where the index is expected to be very high in areas where turtles are more abundant and fall in greater numbers
37 in the traps. Since we are advocated at trapping turtles in the Slidell area, we do not have data to report yet.
Future Plans Since the beginning of the project we have overcome several drawbacks. First we identified the best areas on the West of Lake Maurepas to trap turtles. Second, we have developed and refined the blood sampling technique that we have successfully used to complete the salinity exposure experiments and will use to complete the experiments with turtles captured in the wild. Third, the lack of a graduate student supported by this grant has been compensated by hiring very competent undergraduate students. These are a senior (Alex Mattheus) and a freshman (Judd Thompson), who have been certified in the use of University boats through the Turtle Cove boat safety program. These two undergraduates have been heavily involved both in the field and laboratory components of the project. In addition, another undergraduate (Melissa Juno, a junior) has been dedicated at helping with the maintenance of the turtles in the vivarium facilities. All students are now trained on field techniques regarding turtle capture as well as lab techniques involving turtles handling, blood sampling and processing, and are currently training on the conduction of hormonal measurements in the samples taken from the multiple experiments. We plan to have completed all hormonal measurements by the end of the Fall semester. Soon after that we plan to initiate the write up of our data for publication on a scientific journal.
Information Transfer
1. In 5 sentences or less, please describe the overall goal of the project. The overall goal of this project is to demonstrate that the red-eared slider freshwater is an excellent animal model to study the physiological effects of elevated salinity due to saltwater intrusion into the Lake Pontchartrain basin. The main reasons to support this tenet is that this species is abundant in the basin, is not adapted to saltwater and it is easy to manipulate.
2. List the restoration or sustainability questions posed by the study.
a. Does salinity induce a neuroendocrine stress response in freshwater vertebrates? b. Does salinity limit the abundance and distribution of freshwater vertebrates in the Basin? c. Can the data generated by the study provide managers with a dynamic tool to assess the impact of increased salt water intrusion in the Lake Pontchartrain basin?
3. If possible, please list the hypothesized answers to the above questions.
d. I hypothesize that salinity is an environmental stressor to the freshwater turtle. As such, salinity triggers a neuroendocrine stress response in order to mediate the adaptation of this vertebrate to a challenging environment.
38 e. If salinity is stressful to the turtle it is expected to impact the abundance and distribution of the turtle in the Basin.
4. What sorts of management recommendations/implications do you hope to make from this study? The hypotheses of this study have predictive and, as such, management value. For instance, the study can help predict the impact of sustained decreases or increases of salinity in the basin on freshwater vertebrates. This is particularly relevant to water diversion projects as they may need short-term biological indicators to evaluate the effect of increasing freshwater input in the basin. Also, it may help environmental biologists assess the damage to the basin by sustained salt water intrusion as exacerbated by land loss driven by subsidence (long term), seasonal storms (short term), etc.
5. Please list the (a) agencies and geographies (parishes, etc.) and (b) impacted stakeholders (hunters, shrimpers etc.) that will be affected by this study. a) The scope of this project is expected to be of interest to local, state and federal agencies in charge of protecting the environment such as Louisiana Department of Environmental Quality, the Louisiana Department of Wildlife and Fisheries, the Coastal Restoration and Management Division of the Louisiana Dept. of Natural Resources, the US Geological Survey, and the Environmental Protection Agency. The results of the project are expected to be of relevance to all Parishes found in Southeastern and Coastal Louisiana that are affected by salt water intrusion. Among these are the Parishes of New Orleans, St. Tammany, Tangipahoa, St. Bernard, Jefferson, etc. b) Because the project is focused on the effect of salinity on a species of high economic importance to Louisiana, the freshwater red-eared slider turtle, Louisiana turtle farmers are expected to be the most benefited by the results of this project. However, because the project considers the physiological mechanistic impact of salt water intrusion on the turtle the results of the project are expected to have broader implications at the level of the wider Basin as the abundance and distribution of many other freshwater vertebrates may be limited in the Basin by similar mechanisms.
6. With regard to communicating with policy makers and key regulatory agencies, explain how the results of this study may be used to enhance the restoration of Louisiana’s wetlands and/or guide those policy makers in their regional planning efforts.
The value of the results to be derived from this study can be enhanced significantly if conducted also after Mississippi River Diversion projects come into effect. Our study must be seen from the stand point of the establishment of a baseline on the status of salt water-sensitive vertebrates in the basin. If this study is conducted again after Diversion projects come into effect then the impact of such Diversion can be realized from the stand point of these salt- sensitive vertebrates. In essence, the hypothesis of this project predicts that Diversion of Mississippi River waters into the Lake Pontchartrain basin will induce a significant, sustained decrease in salinity throughout the basin. This, in turn, will result in the proliferation of salt water-sensitive species, which will no longer see their distribution limited by salt water intrusion. Specifically, the results of this project may allow managers to determine the optimal
39 amount of freshwater that may be diverted into the Lake Maurepas to provide freshwater species with a suitable environment to live. In specific terms, high salinity is expected to induce an increase in corticosterone, the main stress hormone in turtles. A challenge to this project is to ascertain what the sensitivity of these turtles to salinity stress is.
References:
Boundy, J. and Kennedy, C. 2006. Trapping Survey Results for the Alligator Snapping Turtle (Macrochelys temminckii) in Southeastern Louisiana, with Comments on Exploitation. Chelonia Conservation and Biology, 5(1): 3-9.
40 Genetic variation between Lake Pontchartain and Mississippi River Basin Fishes: Phase II. Kyle R. Piller
Abstract The Lake Pontchartrain Basin harbors a distinctive and every changing fish community that will likely change in the near future due to the construction of an interbasin canal that will connect the Mississippi River and Lake Pontchartrain Basins. Although the influx of water is aimed at restoring the wetlands around Lake Maurepas by providing freshwater to the system, it also may negatively impact the ichthyofauna of basin through homogenization of genetically distinctive stocks of fishes. Human manipulation of stocks via intentional introductions can disrupt locally adapted characteristics through interstock hybridization and concomitant disruption of co-adapted gene complexes, which are often manifested in phenotypic and physiological characteristics, including decreased growth, survival, and reproduction. The PI is currently examining genetic differentiation between Lake Maurepas and Mississippi River Basin fish populations of bluegill (Lepomis macrochirus). This present study expanded the PI’s Phase II-III EPA study and is providing additional data to examine interbasin genetic differentiation from a second recreationally important species that occurs in both basins. Tissue samples have been gathered from multiple populations of bluegill in each basin. High- resolution nuclear markers (microsatellite loci) are being used to quantify and assess levels of genetic divergence between populations in both basins in an effort to determine the potential genetic impacts of this diversion on these populations. The diversion of water for coastal areas has been proposed as a potential tool for coastal restoration. The information derived from this proposed project is critical to future water diversion projects that may be implanted throughout the Gulf Coast.
Results/Discussion
Approximately 200 individual bluegills (Lepomis macrochirus) have been collected from five locations in the Lake Pontchartrain and Mississippi River basins. DNA from all of these individuals has been extracted and microsatellite data has been collected from seven loci (Lma20, 117, 121, 102, 87, 21, and 10) previously used in studies of Centrarchid population genetics.
Locus Comparisons Data suggests that the loci chosen in this study are highly variable and have the power to provide informative information regarding gene flow within and among both drainage basins. Across the seven loci, the number of alleles per locus ranges from 20-36. Locus Lma20 is the most variable locus (36 alleles) whereas Lma87 is the least variable with (20 alleles) (Table 1).
41 Table 1. Summary of genetic variation by microsatellite locus. Numbers represent the number of alleles/locus/population.
Locus Pass Manchac Atchafalaya Devis Amite Blind River Total Number of Average (LP) River (MR) Swamp River (LP) Alleles/Locus Alleles/Locus (MR) (LP) LMA102 15 16 14 19 17 27 18.0 LMA87 10 12 9 11 10 20 12.0 LMA21 24 24 17 27 18 35 24.2 LMA20 22 24 21 29 24 36 26.0 LMA117 17 19 14 20 12 27 18.2 LMA121 15 16 13 15 14 21 15.7 LMAR10 21 19 22 28 20 34 24.0
Population Variation Genotypic data has been gathered from five populations. The Amite River (Lake Pontchartrain basin) is the most genetically variable population, averaging 21.29 alleles per locus (Table 2), whereas the Devil’s Swamp population (Mississippi River basin) is the least variable population, averaging 15.71 alleles per locus.
Table 2. Summary of genetic variation by population.
Sample Population size Loci typed Unbiased Hz Obs Hz # Alleles/locus
Pass Manchac (LP) 40 7 0.908 0.904 17.71
Atchafalaya River (MR) 48 7 0.905 0.908 18.57
Devis Swamp (MR) 31 7 0.867 0.860 15.71
Amite River (LP) 60 7 0.878 0.869 21.29
Blind River (LP) 28 7 0.898 0.929 16.43
The levels of variability for these microsatellite loci are very different from the levels of variability observed among blue catfish from similar locations (Piller and Cordes, unpubl.). This suggests that differences in migratory abilities have likely impacted differentiation and gene flow for these populations. If each population were isolated and divergent, expected heterozygosities (HE) values would be lower than the observed heterozygosity (HO) values. In this study, nearly all HE values are similar to or higher than the HO values which is indicative of recent gene flow among populations and the lack of differentiation among populations. Despite the low dispersal abilities of bluegill, historic and contemporary gene flow has been high among the populations. The fixation index (FST) is a standard measure of population differentiation that ranges from 0 to 1 and high rates of gene flow result in low FST values. In this study, all of the fixation indices are low, but several are statistically significant (Table 3). However, several have questioned the statistical significance of microsatellites with low FST values, like the
42 situation recovered in this study. Due to their high mutation rate, microsatellites often display significance despite low fixation values and this significance often has no real biological meaning. Therefore, other analytical methodologies are often incorporated to confirm whether the significance has a biological explanation.
Table 3. Summary of pairwise FST values of bluegill in the Lake Pontchartrain and Mississippi River basin. Populations that are significantly different are in bold. 1 2 3 4 5 1 Pass Manchac (LP) 0 2 Atchafalaya River (MR) 0.0007 0 3 Devils Swamp (MR) 0.0169 0.0149 0 4 Amite River (LP) 0.0159 0.0186 0.0026 0 5 Blind River (LP) 0.0098 0.0029 0.0133 0.017 0
Isolation by Distance Individuals are often spatially distributed across the landscape and, as a result, populations are often genetically isolated from one another due to the low dispersal or the existence of geographic barriers. If there is significant difference among the populations, one would expect the data to show a pattern of isolation by distance, where geographically distant populations are more genetically differentiated in comparison to geographically proximate populations. The IBD program recovered no isolation by distance patterns (r= 0.4336 p=0.9940) for bluegill in these basins.
Fig. 1. Isolation by distance diagram generated for pairwise comparisons of genetic distance of bluegill in the Lake Pontchartrain and Mississippi River basins.
Summary Multiple independent analyses of the bluegill microsatellite data suggest that the populations are not genetically differentiated from one another within basins or between basins. The lack of differentiation is likely due to the recent (in geologic terms) isolation of populations in the Mississippi River and Lake Pontchartrain basins, and the very large population densities of bluegill which can facilitate gene flow across the landscape. This study suggests that there is genetic homogeneity among bluegill in both basins and indicates that the
43 proposed Hope Canal will likely have minimal impacts on genetic structure of bluegill in these basins.
Information Transfer Freshwater diversions are routinely being offered as a valuable tool for wetland restoration, however, the potential genetic impacts that this type of restoration project has on native species has not been thoroughly investigated. This is particularly the case in Louisiana, which has many on-going or proposed freshwater diversion projects. This present study focuses on the evaluation of this restoration technique and is aimed at assessing the potential impacts that it has on genetic diversity and biodiversity. Not only will quantitative baseline genetic data be beneficial for this particular diversion project, but more importantly, this data will serve as a model study for any future wetland restoration diversion projects that are aimed at preserving biodiversity and genetic integrity while restoring coastal and wetland habitats. The data from this EPA project (bluegill), and the PI’s Phase II-III project (blue catfish) also should provide a comprehensive overview of the impacts of life-history on genetic differentiation for two species with varying fecundities, migratory abilities, and sensitivities to fishing pressure. This data is critical and will be useful to policy makers including state and federal agencies, including the US Army Corps of Engineers and the Louisiana Department of Wildlife and Fisheries, because these two agencies are the principal players in wetland restoration.
44 Exploring Your Environment: EYE on Southeast Louisiana PI: Dr. Deborah Dardis
Abstract
Phase IV of the Western Lake Pontchartrain Basin Research Program’s Educational Outreach Component is a continuation of Phases I - III activities. The project was designed to increase awareness of: the deterioration of southeast Louisiana’s wetlands, the contribution of human activity to this deterioration, the economic, cultural, and social ramifications of the ecosystem’s demise, and the current research performed by local universities on habitat restoration and sustainability.
Educating the teachers of southeast Louisiana is an important first step in the process of educating the general public on these issues. Teachers will, in turn, impact thousands of students of all ages, who will ultimately become the stakeholders and decision-making citizenry of the area. Phase IV money will be used to continue the professional development of area teachers during Spring 2007 and Summer 2008.
Primary Objectives
The objectives were to: provide teachers with an overview of the ecology of the Lake Pontchartrain basin, stimulate an awareness in teachers of the important function the basin plays in the lives of the surrounding population, provide teachers with opportunities to see researchers in action, provide teachers with standards-based activities and lessons for classroom implementation, provide teachers with the opportunity to bring students to the Manchac area to learn about wetland ecology.
Results
No money was spent from this budget last year.
45 Future Plans
Phase IV will be implemented during the Spring and Summer of 2008. Planning for a K-12 teacher workshop will begin in February 2008 and continue through May 2008. Implementation is projected to occur during the month of June.
Technology Transfer
1. In 5 sentences or less, please describe the overall goal of the project.
The project was designed to increase awareness of: the deterioration of southeast Louisiana’s wetlands, the contribution of human activity to this deterioration, the economic, cultural, and social ramifications of the ecosystem’s demise, and the current research performed by local universities on habitat restoration and sustainability.
2. From a policymaker’s point of view, why is this study needed?
Educating the teachers of southeast Louisiana is an important first step in the process of educating the general public on these issues. Teachers will, in turn, impact thousands of students of all ages, who will ultimately become the stakeholders and decision-making citizenry of the area.
3. List the restoration or sustainability questions posed by the study and if possible, the hypothesized answers to the above questions.
NA
4. Please list the (a) agencies and geographies (parishes, etc.) and (b) impacted stakeholders (hunters, shrimpers etc.) that will be affected by this study.
Teachers from surrounding parishes will be recruited. There is potential for teachers, students, parents and the community-at-large to be impacted in the following parishes: St. Tammany, Tangipahoa, Washington, St. Helena, East Baton Rouge, Livingston, St. John, St. Charles, Jefferson, St. Bernard, Plaquemine
5. With regard to communicating with policy makers and key regulatory agencies, explain how the results of this study may be used to enhance the restoration of Louisiana’s wetlands and/or guide those policy makers in their regional planning efforts. (i.e.,
46 What sorts of management recommendations/implications do you hope to make from this study?)
This project does not directly interface with policy makers.
47
Phase V Annual Reports
De-energizing Hurricanes with Cypress/Tupelo Buffers: a Plan to Restore the Repressed Swamps of the Lake Pontchartrain Basin by Using Point and Nonpoint Freshwater Sources. Gary P. Shaffer1, Hassan Mashriqui2, and Molly McGraw3
1Department of Biological Sciences, SLU-10736 3Department of Sociology and Criminal Justice, SLU-10686 1,3Southeastern Louisiana University, Hammond, LA 70402 2Hurricane Center, Department of Oceanography and Coastal Sciences Louisiana State University, Baton Rouge, LA 70803
Abstract
The problem is hurricanes and the flood and wind damage that accompanies them; wetlands offer a partial solution. Wetlands are known to de-energize storms, but not all wetlands are created equal. In particular, forested wetlands dominated by baldcypress (Taxodium distichum) and water tupelo (Nyssa aquatica) are far less susceptible to storm damage than most other wetland types, such as bottomland hardwood forests and fresh and brackish marshes. In this study we will (1) follow the production and compositional response of the herbaceous and woody vegetation of the Maurepas swamp to the 2005 hurricanes, (2) determine the relationship between density of canopy trees and frequencies of midstory wind throw, (3) isolate all substantial point and nonpoint sources of potential freshwater input in the northern Pontchartrain Basin and build a geographic information system (GIS) of these sources and the spatial extent of currently repressed swamp (swamp that has converted to marsh or open water) that could be restored by these sources, and (4) model the relationship of area of swamp and energy reduction of storms of varying strength, and compare this with other types of wetlands. Using point and nonpoint sources of fresh water to restore swamp will serve the dual benefits of improved water quality, through denitrification and assimilation, and improved wetland health. The GIS has been produced in ArcGIS, the same package being used to produce the overall PBRP GIS and all of our data files are Excel-friendly. Point and non-point sources have been mapped and we are in the process of prioritizing them using proximity to wetlands and area of potential benefit. Our monitoring efforts in the Maurepas swamp have clearly identified a relationship between basal area of cypress and tupelo canopy tree and wind throw of midstory maple and ash. We also document a clear trajectory from swamp to marsh and open water over the seven year study and show that the 2005 hurricanes improved marsh production by detrimentally affecting tree production. Modeling the storm surge reduction capacity of baldcypress – water tupelo swamps will be conducted during year 2 of our project.
48
Project Objectives
Baldcypress (Taxodium distichum) – water tupelo (Nyssa aquatica) swamps historically comprised 90% of the wetlands in the Lake Pontchartrain Basin (Saucier 1963). This coverage has been radically reduced and the swamps that remain have been classified as mostly non- sustainable (Chambers et al. 2005, Lake Pontchartrain Basin Foundation 2005, Shaffer and Day 2007, Shaffer et al. 2007). Several projects have been proposed to help restore these swamps, but Hurricanes Katrina and Rita have altered the way we should think about wetland restoration in general. In terms of flood- and wind-damage reduction, swamps may be far superior to other wetland habitat types, even mangrove forests which were instrumental in protecting villages during the recent Asian tsunami (Danielsen et al. 2005). If so, we need to re-think coastal restoration strategies, tailoring them to storm-protection alternatives (Boesch et al. 2006, Costanza et al. 2006). Only live oak (Quercus virginica) and palms are more resistant to wind throw than baldcypress and water tupelo (Williams et al., 1999). Cypress - tupelo swamps faired far better than other forest types in Hurricanes Camille (Touliatos and Roth 1971), Andrew (Doyle et al. 1995), and Hugo (Gresham et al. 1991, Putz and Sharitz 1991). In addition, fresh, intermediate, and brackish marshes suffered vastly greater loss in Hurricanes Katrina and Rita than did cypress - tupelo swamps (Barris 2006). Katrina caused wind throws of up to 80% of the bottomland hardwood forests of the Pearl River Basin (with an estimated loss of 900 million board feet of lumber in the Honey Island swamp alone), while contiguous swamps remained largely intact (Randy Myers, LADWF, pers. comm.; also compare 2004, 2005 imagery on LADNR website). Initial observations in the Maurepas swamp indicate minimal wind throw of overstory trees, but light to moderate crown damage. In contrast, midstory wind throw was severe in certain areas and appears to be a function of overstory density. Herein we quantify the relationship between wind throw and overstory tree density, which could be useful in determining optimal densities of artificial plantings. We also monitor post-hurricane tree and herbaceous ground cover production and compare it with that of normal- and drought-year conditions. Although baldcypress – water tupelo swamps are extremely resistant to wind throw and deep flooding, they are less resistant to saltwater intrusion and thus require a reliable source of fresh water for system flushing following tropical storm events. We have built a geographic information system (GIS) that contains point and non-point freshwater sources on the North Shore from Baton Rouge to the Pearl River. These freshwater sources are currently being prioritized using proximity to repressed swamp and potential area of benefit. The analysis focuses on wastewater treatment facilities and potential Mississippi River diversion sites, as these sources show the highest potential benefits (Shaffer and Day 2007). At present, most of these sources are input to the Basin to maximize drainage efficiency. Freshwater is routed into ditches and canals that carry it directly to the lakes, bypassing wetland contact. This creates a “lose-lose” situation as potential for eutrofication is maximized and the wetlands remain nutrient starved. To solve this problem, we propose “reverse marsh management” (Shaffer and Day 2007). Reverse marsh management calls for re-routing the water to maximize sheet flow, enhance water quality and several of the “multiple lines of defense” proposed by Lopez (2006), increase wetland net primary production, accretion, and carbon sequestration (Trettin and
49 Jorgensen 2003), and decrease saltwater intrusion and storm damage. In addition, implementation of the proposed river diversions at Violet, Bonnet Carre, La Branche, and the Maurepas swamp (Louisiana Coastal Wetlands Conservation and Restoration Task Force and the Wetlands Conservation and Restoration Authority 1998) will greatly enhance restoration of historic salinity conditions. Ultimately, we must close the Mississippi River Gulf Outlet (MR- GO) to help approximate historic salinity regimes and further assist in storm-damage reduction, but that issue is beyond the scope of this report. One concern that managers and the general public have with restoring repressed baldcypress – water tupelo swamps is the amount of time required for swamp-like characteristics to emerge and manifest. Fortunately, given favorable hydrologic conditions, cypress and tupelo seedlings can reach greater than 10-meter heights within one decade (Kruass 2002). One of the main objectives of this study is to isolate freshwater sources to provide such favorable hydrologic conditions.
The research resulting from this effort will: (1) compare post-hurricane production and compositional response of the herbaceous and woody vegetation of the Maurepas swamp to that of “normal” and drought years, (2) determine the relationship between basal area of canopy trees and frequencies of wind throw of midstory trees, (3) isolate all substantial point and non-point sources of potential freshwater input to the degraded wetlands of the northern Pontchartrain Basin and build a geographic information system (GIS) of these sources and the spatial extent of currently repressed swamp that could be restored by utilizing these sources, and (4) model the relationship of area of swamp and energy reduction of storms of varying strength, and compare this with other types of wetlands.
Methodology
The effects of crown damage and wind throw were directly assessed through measurements of wood and litter production. We also have a 7-year record of herbaceous composition and production to compare pre- and post-hurricane measurements. In addition, we have related basal area of overstory trees to wind throw of midstory trees by assessing our fifty two 625m2 permanent stations, which vary from sparse to dense canopy cover. Most of our GIS data were obtained from LADEQ, focusing on small to large wastewater treatment facilities. These data were augmented with data from proposals to divert Mississippi River water at Violet, Bonnet Carre, La Branche, Romeville, Hope Canal, and Bayou Manchac. Now that the GIS is built, this year we will estimate the extent of repressed swamp that could be converted back into healthy swamp, under various management scenarios. Thus far we have concentrated on municipal wastewater treatment facilities, subdivisions treating their own sewage, non-point source drainage features, and potential Mississippi River diversion sites. Eventually this GIS will include data on storm water pumps and non-contact industrial cooling water. At present, most of these sources are input to the Basin to maximize drainage efficiency. Freshwater is routed into ditches and canals that carry it directly to the lakes, bypassing wetland contact and degrading water quality (e.g., South
50 Slough, Reserve Relief Canal, Hope Canal, Amite river Diversion Canal, New Cut Canal). This creates a “lose-lose” situation as potential for eutrophication is maximized and the wetlands remain nutrient starved. In contrast, re-routing the water to maximize sheetflow will improve water quality, increase wetland net primary production, and decrease saltwater intrusion. Most analysis, processing, and mapping was preformed using Arc GIS v9.2 by ESRI. Microsoft Excel was used to modify the latitude-longitude information to an importable format. Subsequent modifications of the tabular data were performed using the Arc GIS v9.2 by ESRI edit toolbar. Raster data: All DOQQs and LIDAR imagery were collected from the Louisiana State Wide GIS. All DOQQs in the area of interest were placed into a personal geodatabase. This was done to stitch all of the images together for ease of viewing (i.e., press one button to see all images as opposed to 144 buttons). All LIDAR imagery was combined to form one image of the area of interest (AOI), namely the upper Lake Pontchartrain Basin. This was performed by using the mosaic tool in ARC Toolbox. Hill-shade imagery was constructed by utilizing the mosaic LIDAR image and the 3D analyst tool for creating hill-shade effects. Vector data: Road data was collected from the Louisiana State Wide GIS. Road information from Ascension, East Baton Rouge, Iberville, Livingston, St. James, St. John the Baptist, St. Tammany, and Tangipahoa parishes were merged using the merge tool. This merged image was clipped to the AOI using the clip tool. This image was then placed in duplicate into the map table of contents. This was done to facilitate the separation of major roads (interstates and highways) from minor roads. Rivers and lake water bodies were acquired from the United States DVD rivers and streams file provided by ESRIs ArcGIS 9 Data and Maps media kit. Data was clipped to the AOI then set to display stream/rivers, canal/ditches, artificial paths, and connectors. Waste discharge facility information was provided by the Louisiana Department of Environmental Quality. They provided the facility name, permit number, permit type, physical address, city, parish, latitude and longitude. Latitude and longitude were converted from degrees minutes and seconds to decimal degrees using the following formula (DD MM SS = decimal degrees when ((DD + (MM * 1/60) + (SS * 1/60 * 1/60)). This tabular information was then imported into a personal geodatadase where it was exported into the GIS. All data points that fell outside of the AOI were eliminated. The general permit types were as follows: LAG53: discharges less than 5,000 gallons per day (gpd) LAG54: discharges between 5,000 and 25,000 gpd LAG56: discharges between 25,000 and 50,000 gpd LAG57: discharges between 50,000 and 100,000 gpd Major Sanitary Discharge: greater than 100,000 gpd These were color and size coded and the level of detail in the GIS varies according to aerial coverage. That is, the overall image is in broad brush and increasing detail is automatically provided as the user increases magnification. Our modeling efforts to quantify the wind- and flood-damage reduction capacities of cypress - tupelo swamps will begin using the parameters derived for mangrove forests subjected to tsunamis (Mazda et al.1997, Massel et al. 1999, Yoshihiro et al. 1997). Research on tsunamis and mangroves is applicable for estimates of storm-surge and wave-energy reduction, but obviously not wind reduction. During October, 2007, we will measure stem density, basal
51 area, and species cover of several plots contiguous with levees in St. Bernard Parish to obtain baseline data on known surge reduction. In general, land reduces the energy of hurricanes in three ways: detachment of the wind from the water, offering friction, and most important for forests that remain intact, damping surge by deflecting it in many directions, which decreases onshore movement while simultaneously de- energizing the storm. Land, in general, will detach the wind from the water. However, forested wetlands offer orders of magnitude more friction and dampening power to decrease wind velocity and, especially, storm surge. This is particularly true of those that are resistant to wind throw such as baldcypress – water tupelo swamps. To model energy reduction, we need to estimate the volume of the vegetation, its extent, and its Reynolds number (Massel et al. 1999, Yoshihiro et al. 1997). Basically the momentum equation simplifies to a balance between the slope of the water surface and the drag and dampening force offered by the land. It also depends on the spectral characteristics unique to each storm, so we will simulate a number of hurricane conditions using models housed at the Hurricane Center of LSU.
Results
Habitat Type Groupings The separate multinomial logistic regression models of habitat type were both significant (year 2000: Likelihood Ratio χ2= 54.15, df=2, p<0.001; year 2001: Likelihood Ratio χ2 = 48.77, df=2, p<0.001). In both datasets, we only retained annual maximum observed salinity and the combined amount of baldcypress and water tupelo litterfall as significant predictors of habitat type. The multinomial logistic models correctly classified 38 out of 40 field-plots with the 2000 data and 36 out of 40 field-plots with the 2001 data. The separation of Throughput and Degraded swamp sites was strong, while the distinction between Relict swamp and either Throughput or Degraded swamp was ambiguous at some sites (Figure 2), leading us to drop 10 of the 40 sites as training sites in the remote sensing analysis.
Environmental Variables The analysis of well-water salinity data revealed that salinity followed a U-shaped pattern from 2000 - 2006 (quadratic contrast F1,259 = 406.16, p < 0.00001; Figure 3) with the highest salinities occurring during the severe drought of 1998 - 2000 followed by 2006, another drought year. Overall, salinity was highest at Degraded sites and lowest at Throughput sites (linear contrast F1,259 = 168.92, p < 0.00001). Soil salinity also was found to decrease with increasing distance from Pass Manchac, as well as with increasing distance from the margin of Lake Maurepas into the interior swamp. Bulk densities differed among site groupings (F2,277 = 72.28, p < 0.00001; Figure 4). The highest bulk densities were found at the Throughput sites (mean = 0.158 ± 0.013 g/cm3) and the lowest at Degraded sites (mean = 0.054 ± 0.001 g/cm3). Relict sites had intermediate bulk densities (mean = 0.086 ± 0.002 g/cm3). Light penetration followed the opposite pattern of the total basal area of trees per plot (Figure 4), with greater amounts of penetration as the swamp varied from Throughput to Relict to Degraded (linear contrast F2,277 = 701.81, p < 0.00001). Light penetration continues to increase
52 annually, as large trees continue to suffer mortality and recruitment is absent at the Degraded sites.
Tree Mortality The Maurepas swamp is in a steady state of rapid decline, perhaps best shown by the mortality of canopy and midstory trees (Figure 5). Over the past 7 years, nearly 20% of the original 1,860 trees in our study plots have suffered mortality, and recruitment of baldcypress and water tupelo saplings is essentially absent. In 2000, almost all of the mortality occurred at the Degraded sites, but the highest rates are now experienced in the Relict sites, largely because there are very few trees left to die at Degraded sites. The few remaining trees at Degraded site are nearly all baldcypress, which is more tolerant to saltwater intrusion events. Mortality is highest for midstory species (Figure 5), nearly all of which are swamp red maple and green ash.
Herbaceous Vegetation Nutrient Enrichment For the uncaged treatments, nutrient enrichment at all levels had little effect on vegetative biomass production (Figure 6), indicating grazers such as nutria and deer had a large impact on the fertilized plots. The cage effect was highly significant for both 2002 (F1,51 = 7.032, p = 0.0102) and 2003 (F1,48 = 12.390, p = 0.00084). Although a clear trend of increased vegetation production with increased nutrient enrichment exists for 2002 (Figure 6), the fertilizer effect was not significant (F3,51 = 2.080, p = 0.154). By 2003, nutrient augmentation showed a highly significant increase in herbaceous production (F3,48 = 4.685, p = 0.0053; Figure 6), with a 50% increase for the loading rate of 11.25 g N m2 year-1 and a 100% increase for the loading rates of 22.5 g N m2 year-1 during spring (2X) and throughout the growing season (2X Biannual), which did not differ from one another.
Annual Production Herbaceous production was highest at the Degraded sites (mean = 697.33 ± s.e. 71.84 g m-2 y- 1) followed by Relict sites (mean = 381.60 ± s.e. 26.11 g m-2 y-1), and lowest for Throughput -2 -1 sites (64.31 ± s.e. 13.64 g m y ; F2,256 = 3.26, p = 0.040; Figure 7). There was a strong linear trend of increased herbaceous production from 2000 – 2006 (linear contrast F = 119.141, p < 0.00001). Depressed production in 2001 and 2002 is thought to be a carryover effect from the drought as it took several years for soil salinities to freshen (Figure 3). Higher production in recent years is partially attributable to a shift to more salt tolerant herbaceous species and decreased competition with tree species with continued high mortality rates, especially at the Degraded sites. Most of the herbaceous biomass production could be attributed to 15 dominant ground-cover species, which together represented 97% of the total herbaceous cover throughout the study. Alligatorweed (Alternanthera philoxeroides), smartweed (Polygomum punctatum), and arrow arum (Peltandra virginica) were the most ubiquitous herbaceous species in the swamps of southern Maurepas. Pickerelweed (Pontederia chordata) decreased in abundance as habitats became saltier and more open, whereas bulltongue (Sagitarria lancifolia) and fall panicum (Panicum dicotomiflorum) became more abundant. Maidencane (Panicum hemitomon) and
53 spike rush (Eleocharis spp.) were generally only present at the interior sites and in ponding areas of lake sites, and appear to be indicator species of marsh converting to open water.
Primary Production of Trees
Total tree primary production differed between habitat types (F2,126 = 14.126, p < 0.00001; Figure 8) and years (F6,126 = 9.997, p = 0.00001; Figure 7). Bulk density and salinity were significant covariables in the model (F1,256 = 12.940, p = =0.00039, F1,256 = 2.058, p = 0.020, respectively), indicating that tree primary production was higher at sites with higher bulk densities and lower salinities. The highest rates of total tree primary production were found at the Throughput sites (mean = 737.03 ± s.e. 37.18 g⋅m-2⋅yr-1), followed by Relict sites (mean = 322.48 ± s.e. 13.88 g⋅m-2⋅yr-1), followed by Degraded sites (mean = 144.36 ± s.e. 37.18 g⋅m- 2⋅yr-1). In general, leaf litter and wood production followed similar patterns through time (Figure 7) with the lowest production overall occurring in 2003 (mean = 104.56 ± s.e. 10.34 g m-2 year-1, 73.03 ± s.e. 24.25 g m-2 year-1, respectively). Interestingly, a general increase in production was experienced by the herbaceous community in 2003, whereas the forest community continued to decline until 2004. For total annual (leaf plus wood) tree production, an interaction existed between habitat type and the three categories of species (F = 17.34, p < 0.00001; Figure 8). The interaction occurred for Relict sites where baldcypress had similar growth rates as water tupelo and ‘Other’. Although baldcypress was the least abundant species of the three categories at almost all sites (Hoeppner, 2002), it had nearly twice the average growth rate (mean = 171.83 ± s.e. 8.33 g m-2 year-1) as water tupelo (96.46± s.e. 5.70 g m-2 year-1) or ‘Other’ (mean = 91.10 ± s.e. 5.53 g m-2 year-1).
Total Primary Production In a period of only 7 years, the Maurepas swamp has switched from an ecosystem dominated by tree production to one dominated by herbaceous production (Figure 9). From 2000 – 2003, overall production was similar, with a decrease in tree production compensated for by an increase in ground cover production. Overall production from 2004 – 2006 was significantly greater than that of 2000 – 2003, yet tree production continued to fluctuate around 400 g m-2 year-1. The BVSTEP Routine (Clarke and Warwick, 2006) determined that the combination of factors that best described community structure was total tree production and herbaceous production (Spearman correlation r = 0.964; Figure 10). These two factors separated the Throughput sites from the Degraded sites, with Relict sites containing some overlap with both, as in the logistic regressions (Figure 2). The ordination, based on non-metric multidimensional scaling, shows a striking temporal trajectory from less forest-like characteristics to more marsh-like characteristics (Figure 10). Degraded sites became completely dominated by herbaceous vegetation from 2000 – 2006, Relict sites late in the study transitioned toward Degraded sites early in the study, and Throughtput sites transitioned toward Relict sites following the severe drought (i.e., 2002), and late in the study.
54 The 2005 Hurricanes The 2005 hurricanes appear to have decreased canopy tree production primarily by snapping limbs, whereas midstory trees suffered extensive wind throw where canopy basal areas fell below about 30 m2 ha-1 (Figure 11; Sites with basal areas < 30 m2 ha-1 that fell on the x-axis had lost all midstory trees prior to the 2005 hurricanes due to saltwater intrusion.). Degraded sites suffered 100% loss of midstory species, whereas Throughput sites, with many more midstory stems, suffered very low mortality due to wind throw (Figure 12).
Potential Surge Reduction by Cypress Swamps Marshes can slow down surge by storing water in the early stage of the storm and large trees can provide obstructions to the surge and wave propagations and reduce dynamic loads on the infrastructures (Figure 13). Field data after hurricanes Katrina and Rita showed that hurricane surge and wave energy could be reduced by non-structural measures such as coastal restoration and wetland creation. Most storm surge estimates are based on 2D models. Generally, a 2D model utilizes Manning’s friction coefficient to represent wetlands in the model. For large vegetation or trees (such as baldcypress – water tupelo swamps) 2D representations under predict the surge propagation by not including physical presence of trees in the models. In this research, we are looking in to model resolutions and node elevations to better represent tress in the model and to create a flow around trees. Initial results suggest that raising nodes can mimic trees that are not totally inundated and can obstruct flows around them and reduce flow velocity (Figures 14-16). At this time, we are working to improve model resolution and other available techniques to better estimate surge reduction by cypress swamps and validate numerical results with field data.
Discussion
Flooding has been reported to have doubled in the Manchac Wildlife Management Area adjacent to the Maurepas swamp since 1955 due to sea-level rise and subsidence (Thomson et al., 2002). Currently, the Maurepas swamps are often lower in elevation than the Lake, rendering flooding semi-permanent. Furthermore, flood control levees and abandoned raised railroad tracks have impounded much of the remaining swamps, causing throughput to be low. These swamps have been cut off from the sustaining, spring floods of the Mississippi River for over a century and are in varying states of decline. Until this study was undertaken, the decline was evidenced by qualitative information such as dead and dying canopies of the predominant water tupelo trees. We now have quantitative information that allows us to compute the likely benefits of a future with a re-introduction of Mississippi River water into the southwestern Maurepas swamp in comparison to the continued demise of the swamp ecosystem in a future without such a project (Shaffer et al., 2003). The Maurepas swamps are characterized by nutrient poor waters with nitrate levels less than 1% of those found in Mississippi River water (Lane et al., 2003). In addition, the soils are of extremely low strength indicative of stress such as saltwater intrusion events that typically occur during late summer and fall. The mean salinity of lake water measured at the Manchac
55 bridge also has increased gradually since 1951 (Thomson et al., 2002). Severe increases in salinity, like those experienced during the droughts in 1999 and 2000, may be prevented or greatly ameliorated by the increased freshwater throughput that the proposed river re- introduction would offer. It is likely that the influences of freshening would be felt in wetlands as distant as Lake Pontchartrain (Figure 13) because the smallest proposed diversion of 42.5 m3 s-1 would replace all of the water in Lake Maurepas twice each year and it can only exit to Lake Pontchartrain through Pass Manchac and North Pass. The soil characteristics at the majority of the study sites are indicative of a lack of riverine influence (lack of sediment input and throughput) as evidenced by high soil organic matter content and low bulk density values (DeLaune et al., 1979; Hatton, 1981; Messina and Conner, 1998). With the exception of Throughput sites, soil bulk densities are in the range of those typically found in fresh and oligohaline marshes that are located interior of streamside hydrology effects (Hatton, 1981). This agrees with the continued mortality of trees and the conversion of the system to a more herbaceous plant community. Our study, and previous studies by Greene (1994), Myers et al. (1995), Boshart (1997), and Effler et al. (2006), indicate that the herbaceous and woody vegetation in the Maurepas swamp is nutrient limited. The dramatic increases in herbaceous standing crop with increased nutrient loading were only evidenced in caged plots as herbivores targeted the vegetation with increased protein content in uncaged, fertilized plots. Fertilizing at a loading rate of 22.5 g N m-2 year-1, which simulates a river diversion of 85 m3 s-1, more than doubled biomass production, when compared with caged control plots. Although the second application of fertilizer during the summer did not increase production over a single application, it is during the fall that saltwater intrusion events generally occur. Therefore engineering the river re- introduction to allow for fall operation remains an important design feature. The difference in forest structure among different areas in the Maurepas swamp also is an indication of the health and future of these sites. Overall, the overstory is dominated by either water tupelo, baldcypress, or both, while the midstory is largely dominated by high numbers of swamp red maple and green ash, both of which are more shade tolerant than either of the dominants (Fowells, 1965). Similar observations have been made in comparable swamps in the Barataria Basin (CONNER and DAY, 1976). Wax mytle (Morella cerifera), Chinese tallow (Triadica sebiferum), and black willow (Salix nigra) dominate the mid-story in areas of disturbance that were characterized by more open canopies and measurable saltwater intrusion effects. Shrub-scrub habitats are often observed on the transitional edges between marshes and forested wetlands or uplands (White, 1983; Barras et al., 1994). Diamond oak (Quercus obtusa) and green ash were found in greater abundance at sites characterized by higher bulk densities, which were indicative of increased throughput and generally less flooding. These observations support similar findings from wetland plant ordinations by White (1983) in the Pearl River, Louisiana, and Rheinhardt et al., (1998) in the forested riverine wetlands of the inner coastal plain of North Carolina. As Chinese tallow has been found to be more shade, flood, and salt tolerant (Jones et al., 1989; Conner and Askew, 1993) than several other native wetland tree species, this invasive species may become more dominant in the coastal wetlands of the southeastern United States (Conner and Askew, 1993). Stem densities at Throughput sites are similar to densities reported for impounded (Conner et al., 1981; Conner and Day, 1992) or continuously flooded (Dicke and Toliver, 1990) swamps throughout Louisiana, whereas stem densities at Relict sites are less than those reported for impounded swamps (Table 1). Average stem densities at Degraded sites are not even half of
56 those reported for impounded swamp sites, most likely due to the fact that neither water tupelo, swamp red maple, or green ash have salt tolerances that could withstand the chronic salinity conditions of 2 - 4 ppt found at these sites. Conner et al. (1997) and Pezeshki (1989) reported that these three species showed signs of stress and reduced growth at salinities as low as 2-3 ppt. Black gum (Nyssa sylvatica var. biflora) seedlings experienced 100% mortality when exposed to chronic flooding with 2 ppt (McCarron et al., 1998). Likewise, the relatively low stem densities observed at the Relict swamp sites (Table 1) are primarily the result of the decreased abundance of green ash and swamp red maple in the impounded and stagnant hydrologic regimes characteristic of these sites. In general, basal area followed very similar patterns as stem density. During our 7-year study, nearly 20% of the monitored trees suffered mortality, with mortality as high as 87% at one Degraded site. In terms of above-ground net tree primary production, only the most productive sites of the Maurepas swamp compare well with natural, periodically flooded cypress-tupelo swamps (Carter et al., 1973; Conner and Day, 1976; Conner et al., 1981; Megonigal et al., 1997) - and then only during years of normal precipitation. The vast majority of the Maurepas swamp is either Relict or Degraded (Figure 13) and these range in total tree production between swamps that have been identified as either nutrient-poor and stagnant (Schlesinger, 1978), just stagnant (Taylor, 1985; Mitsch et al., 1991), or near-continuously flooded cypress swamps (Megonigal et al., 1997). The remarkable linear increase of herbaceous production at Relict and, more emphatically, Degraded sites from 2000 – 2006 is a strong indication that these forested wetlands are converting to marshes (Barras et al., 1994). We believe that the increased herbaceous production in 2006 was largely a result of the 2005 hurricanes (Turner et al., 2006) as up to 1 cm of sedimentation occurred at sites near the lake margin and light penetration was increased by wind throw of midstory species. We expect this trend to reverse itself as the marsh degrades, as it has on the nearby Manchac land bridge. Overall, balcypress was the most productive species in the Maurepas, while water tupelo was the second most productive. This finding agrees with the observation that these two species are the canopy dominants, make up the majority of the basal area found at each site, and are the most flood-tolerant tree species in this ecosystem (Hook, 1984). Furthermore, the higher biomass production of baldcypress also agrees with several studies that reported baldcypress seedlings to be more tolerant of low salinity and permanent flooding than water tupelo, swamp red maple, and green ash (Dickson and Broyer, 1972; Pezeshki, 1989; Keeland and Sharitz, 1990; Conner et al., 1997). The Maurepas swamps are nearly continuously flooded and largely impounded, which prevents seed germination and recruitment of baldcypress and water tupelo (DuBarry, 1963; Harms, 1973; Conner and Day, 1976; Williston et al., 1980; Conner and Day, 1988; Myers et al., 1995; Souther and Shaffer, 2000). Modeling efforts by Conner and Brody (1989) have shown that even though baldcypress and water tupelo are flood-tolerant (Carter et al., 1973; Brown, 1981; Conner et al., 1981; Mitsch and Rust, 1984), the total basal area of both will decline if water levels continue to rise. Thus, continuous flooding, though not immediately detrimental to these swamps, will lead to their gradual death over time (Harms et al., 1980; Mitsch and Rust, 1984; Conner and Day, 1988; Conner and Brody, 1989; Conner and Day, 1992). The different habitat types identified within the Maurepas swamp (Shaffer et al. 2007) appear to be in various stages along this trajectory of swamp decline, ranging from the continuously flooded but productive Throughput sites to the impounded, flood and/or salinity stressed Relict and Degraded sites, respectively.
57
Hurricane Impacts
Only live oak (Quercus virginica) and palms are more resistant to wind throw than baldcypress and water tupelo (Williams et al., 1999). Baldypress – water tupelo swamps faired far better than other forest types in Hurricanes Camille (Touliatos et al., 1971), Andrew (Doyle et al., 1995), and Hugo (Gresham et al., 1991; Putz and Sharitz, 1991). In addition, fresh, oligohaline, and brackish marshes suffered vastly greater loss in Hurricanes Katrina and Rita than did baldcypress – water tupelo swamps (Barras, 2006). Katrina caused wind throws of up to 80% of the bottomland hardwood forests of the Pearl River Basin, while contiguous swamps remained largely intact (Randy Myers, Louisiana Department of Wildlife and Fisheries, pers. comm.). The Maurepas swamp was no different with respect to canopy species that suffered zero wind throw, but a relationship was found between canopy basal area and wind throw of midstory species, in particular swamp red maple. As basal areas of canopy species dropped below about 30 m2 ha-1, a linear increase in wind-thrown midstory trees existed (Figure 11). At the Degraded sites, all of the midstory trees were lost to the 2005 hurricanes (Figure 12), whereas Throughput sites containing a far greater number of midstory stems, lost very few individuals. It appears that the extensive lateral root systems of baldcypress and water tupelo hold the entire ecosystem together when canopy trees are dense. In terms of flood- and wind-damage reduction, baldcypress – water tupelo swamps appear to be far superior to other wetland habitat types, even mangrove forests which were instrumental in protecting villages during the recent Asian tsunami (Williams et al., 1999; Danielsen et al., 2005). We need to re-think coastal restoration and management strategies, tailoring them to storm-protection alternatives (Boesch et al., 2006; Costanza et al., 2006; Lopez, 2006; Day et al., 2007) that include restoring historic levels of baldcypress – water tupelo swamps.
Reversing the Trajectory of Decline
In summary, the Maurepas swamp is characterized by nutrient poor waters, soils of extremely low strength, nearly permanent flooding in most areas, and saltwater intrusions that generally occur during the late summer and fall seasons. The Maurepas swamp is nitrogen limited, and nutrient stress is potentially as important as salt or flood stress. Furthermore, recruitment of baldcypress and water tupelo saplings throughout the swamp is very low, certainly not sufficient to sustain the aerial extent of current forest. Most of the Maurepas swamp appears to be converting to marsh and open water, primarily due to the lack of riverine input. Salt stress is killing trees proximal to the lake, whereas stagnant standing water and nutrient deprivation appear to be the largest stressors at interior sites. Although baldcypress – water tupelo swamps are extremely resistant to wind throw and deep flooding, they are less resistant to saltwater intrusion and thus require a reliable source of freshwater for system flushing following tropical storm events and during droughts. Swamps can survive short-term salinity pulses (Allen et al., 1994; Campo, 1996; Conner et al. 1997). We are in the process of building a geographic information system that contains all substantial point and non-point freshwater sources, including urban and agricultural runoff, storm water
58 pumps, non-contact industrial cooling water, municipal wastewater treatment facilities, and potential Mississippi River diversion sites. At present, most of these sources are input to the Basin to maximize drainage efficiency. Freshwater is routed into ditches and canals that carry it directly to the lakes, bypassing wetland contact. This creates a “lose-lose” situation as potential for eutrophication is maximized and the wetlands remain nutrient starved. In contrast, re-routing the water to maximize sheet flow would improve water quality, increase wetland net primary production, and decrease saltwater intrusion. Furthermore, implementation of the proposed Mississippi River re-introductions at Violet, Bonnet Carre, La Branche, and the Maurepas swamp (Coast 2050, 1998) will greatly enhance restoration of historic salinity regimes. In addition to the benefits mentioned above, increasing swamp acreage will decrease storm damage, may lead to net sediment accretion, will increase carbon sequestration (Trettin and Jorgensen, 2003), enhance biodiversity, and improve several of the “multiple lines of defense” proposed by Lopez (2006). Ultimately, we must close the Mississippi River Gulf Outlet to help approximate historic salinity regimes and further assist in storm-damage reduction. One concern that managers and the general public have with restoring repressed swamps is the amount of time required for swamp-like characteristics to emerge and manifest. Fortunately, given favorable hydrologic and nutrient conditions, baldcypress and water tupelo seedlings can reach greater than 10-meter heights within one decade. For example, a pilot planting of baldcypress seedlings at the Caernarvon diversion (Krauss et al., 2000) has yielded >10 m tall trees in a decade and all of these resisted wind throw during the hurricanes of 2005. In conclusion, if we are to reverse the trajectory of decline of coastal Louisiana swamps, we must find, and wisely use, point and non-point sources of freshwater currently being wasted. Despite the degraded condition of the majority of the baldcypress – water tupelo swamps of the upper Lake Pontchartrain Basin, healthy areas of swamp still exist. Without exception, each of these swamps receives some form of reliable high quality, nutrient rich fresh water. These forests are either receiving non-point sources of fresh water from urban areas (e.g., forests of Hope Canal and Alligator Island), high quality river water (e.g., forests of Pearl River), or secondarily treated sewage effluent (e.g., forests of Joyce Wildlife Management Area and Bayou Chinchuba). Restoration efforts that include the proper combination of River diversions, treated sewage effluent assimilation wetlands, and rerouted non-point source fresh water, should enable restoration of Lake Pontchartrain Basin’s swamps (Shaffer and Day, 2007).
Information Transfer
This proposal is designed to (1) follow the production and compositional response of the herbaceous and woody vegetation of the Maurepas swamp to the hurricanes, (2) determine the relationship between basal area of canopy trees and frequencies of wind throw, (3) isolate all substantial point and non-point sources of potential freshwater input in the Basin and build a geographic information system (GIS) of these sources and the spatial extent of currently repressed swamp that could be restored by using these sources, and (4) model the relationship of area of swamp and energy reduction of storms of varying strength, and compare this with marsh. All four of these objectives are pertinent and relevant to the restoration and sustainability of the Pontchartrain Basin. Policy makers and stakeholders that will be
59 interested in our findings include those interested in nature’s role in storm-damage reduction and all those involved in making decisions concerning wetlands restoration in the Basin. The investigators will ensure that the information produced in this study is transferred to the appropriate policy makers and stakeholders, primarily by attending meetings designed to discuss management issues in the Lake Pontchartrain Basin. These meetings are generally sponsored by state and federal agencies, and environmental groups such as the Lake Pontchartrain Basin Foundation and The Nature Conservancy. We will provide policy makers and stakeholders with solid evidence that wetlands are not created equal with respect to storm- damage reduction and resistance to storm damage. We will provide a mechanism for prioritizing wetlands restoration projects in the Basin by producing a GIS that displays potential point and non-point freshwater sources that could be utilized for nourishing and restoring swamps, improving water quality, and reducing storm damage. Other researchers could use our protocol on the rest of coastal Louisiana to optimize the marriage of storm- damage reduction and wetlands restoration (Boesch et al. 2006). More formal dissemination of the material produced from this effort will occur through completion of a final report (hard bound, CD) and master’s thesis, annual presentations at regional, national, and international conferences, and manuscripts published in international journals. The GIS will be produced in ArcGIS, the same package being used to produce the overall PBRP GIS and all of our data files are Excel-friendly. Finally, we will be working with our Information Transfer personnel to produce “Briefs” and other materials to broaden the dissemination of this effort.
60 References
Allen, J. A., J. L. Chambers, and D. McKinney. 1994. Intraspecific variation in the response of Taxodium distichum seedlings to salinity. Forest Ecology and Management 70: 203-214.
Barras, J.A. 2006. Land Area Changes in Coastal Louisiana After the 2005 Hurricanes: A Series of Three Maps. U.S. Geological Survey Open-File Report -6-1274. Boesch, D. F., L. Shabman, L.G. Antle, J. W. Day, R. G. Dean, G. E. Galloway, C. G. Groat, S. B. Laska, R. A. Luettich, W. J. Mitsch, N. N. Rabalais, D. J. Reed, C. A. Simonstad, B. J. Streever, R. B. Taylor, R. R. Twilley, C. C. Watson, J. T. Wells, and D. F. Whigham. 2006. A New Framework for Planning the Future of Coastal Louisiana after the Hurricanes of 2005. Working Group for Post-Hurricane Planning for the Louisiana Coast. 48pp. Chambers, J. L., W. H. Conner, J. W. Day, S. P. Faulkner, E. S. Gardiner, M. S. Hughs, R. F. Keim S. L. King, K. W. McKleod, C. A. Miller, J. A. Nyman, and G. P. Shaffer. 2005. Conservation, Protection, and Utilization of Louisiana’s Coastal Wetland Forests. Final Report to the Governor of Louisiana. 102p. Campo, F. M. 1996. Restoring a repressed swamp: the relative effects of saltwater influx on an immature stand of baldcypress (taxodium distichum (L). Rich). Master’s Thesis. Southeastern Louisiana University. Hammond, LA. 89 p. Conner, W. H., K. W. McKleod, and J. K. McCarron. 1997. Flooding and salinity effects on growth and survival of four common forested wetland species. Wetland Ecology and Management 5: 99-109. Danielsen, F., M. K. Sorenson, M. F. Olwig, V. Selvam, F. Parish, N. D. Burgess, T. Hiraishi, V. M.Karunagaran, M. S. Rasmussen, L. B. Hansen, A. Quarto, and N. Suryadiputan. 2005. The Asian tsunami: a protective role for vegetation. Science 310: 643. Doyle, T. W., B. D. Keeland, L. E. Gorham, and D. J. Johnson. 1995. Structural impact of Hurricane Andrew on forested wetlands of the Atchafalaya Basin in south Louisiana. Journal of Coastal Research, Special Issue 21: 354-364. Gresham, C. A., T. M. Williams, and D. J. Lipscomb. 1991. Hurricane Hugo wind damage to Southeastern U.S. coastal forest tree species. Biotropica 23: 420-426. Lake Pontchartrain Basin Foundation. 2005. Comprehensive Management Plan for the Lake Pontchartrain Basin. LPBF, New Orleans, LA 125 p. Lopez, J. A. 2006. The multiple lines of defense strategy to sustain coastal Louisiana. White Paper, Lake Pontchartrain Basin Foundation, New Orleans, LA 21 p. Louisiana Coastal Wetlands Conservation and Restoration Task Force and the Wetlands Conservation and Restoration Authority. 1998. Coast 2050: Toward a Sustainable Coastal Louisiana. Louisiana Department of Natural Resources. Baton Rouge, LA.161 p. Mazda, Y., M. Magi, M. Kogo, and P. N. Hong. 1997. Mangrove on coastal protection from waves in the Tong King Delta, Vietnam. Mangroves and Salt Marshes 1: 127-135. Massel, S. R., K. Furukawa, and R. M. Brinkman. 1999. Surface wave propagation in mangrove forests. Fluid Dynamics Research 24: 219. Putz, F. E., and R. R. Sharitz. 1991. Hurricane damage to old-growth forest in Conaree Swamp National Monument, South Carolina, USA. Canadian Journal of Forest Research 21: 1765- 1770. Saucier, R. T. 1963. Recent Geomorphic History of the Lake Pontchartrain Basin. LSU Press, Baton Rouge, LA, USA.
61 Shaffer, G.P, T.E. Perkins, S.S. Hoeppner, S. Howell, T.H. Benard, and A.C. Parsons. 2003. Ecosystem health of the Maurepas swamp: feasibility and projected benefits of a freshwater diversion. Final Report. Dallas, TX: Environmental Protection Agency, Region 6. 105 p.
Shaffer, G.P. and Day, J.W. Jr. 2007. Use of Freshwater Resources to Restore Baldcypress – Water Tupelo Swamps in the Upper Lake Pontchartrain Basin. White Paper, Louisiana Department of Wildlife and Fisheries, Baton Rouge, 44p.
Shaffer, G.P., Wood, W.B, Hoeppner, S.S, Perkins, T.E, Zoller, J.A, and Kandalepas, D. 2007. Degradation of Baldcypress – Water Tupelo Swamp to Marsh and Open Water in Southeastern Louisiana, USA: An Irreversible Trajectory? Journal of Coastal Research. Trettin, C. C. and M. F. Jorgensen. 2003. Carbon cycling in wetland forest soils. Pages 311- 331 in J. M. Kimble et al. (eds.). The Potential of U.S. Forest Soils to Sequester Carbon and Mitigate the Greenhouse Effect. CRC Press, Boca Raton, FL. Whigham, D. F., J. McCormick, R. E. Good and R. L. Simpson. 1978. Biomass and Production in Freshwater Tidal Marshes of the Middle Atlantic Coast. In: R. E. Good, D. F. Whigham, and R. L. Simpson (eds.) Freshwater Wetlands: Ecological Processes and Management Potential. Academic Press, New York.
Williams, K., Z. S. Pinzon, R. P. Stumpf, and E. A. Raabe. 1999. Sea-level Rise and Coastal Forests on the Gulf of Mexico. USGS-99-441. 63 pp.
Wohlgemuth, M. 1988. Estimation of net aerial primary productivity of Peltandra virginica (L.) Kunth using harvest and tagging techniques. Masters Thesis. College of William and Mary, Williamsburg, Virginia.
Yoshihiro, M., E. Wolanski, B. King, A. Sase, D. Ohtsuka, and M. Mayoi. 1997. Drag force due to vegetation in mangrove swamps. Mangroves and Salt Marshes 1: 193-199.
62 Table 1. Measurements of swamp primary production from several different studies including the Maurepas swamp.
Forest Type (State) Tree Standing Litterfall Stem Above- Reference Biomass (kg/m2) (g⋅m-2⋅yr-1) Growth Ground (g⋅m-2⋅yr-1) NPPa (g⋅m-2⋅yr-1)
Reference Locations
Cypress - Tupelo (LA) 37.5b 620 500 1,120 Conner and Day (1976) Impounded managed swamp 32.8b,c 550 1,230 1,780 Conner et al. (LA) (1981) Impounded stagnant swamp (LA) 15.9b,c 330 560 890 Ibid.
Tupelo stand (LA) 36.2b 379 ------Conner and Day (1982) Cypress stand (LA) 27.8b 562 ------Ibid.
Nutrient-poor Cypress Swamp 30.7e 328 353 681 Schlesinger (GA) (1978) Stagnant Cypress Swamp (KY) 9.4 63 142 205 Taylor (1985), Mitsch et al. Sewage enriched cypress strand 28.6 650 640 1,290 Nessel (1978) (FL) Near-continuously flooded --- 553d 443e 996 Megonigal et al. Cypress-Ash swamp (LA) (1997) f Near-continuously flooded --- 438d 216e 654 Megonigal et al. riverine Cypress-Tupelo swamp (1997) f Naturally flooded swamp (LA) --- 487d 338e 825 Megonigal et al. (1997) f Periodically flooded riverine --- 725d 430e 1155 Megonigal et al. swamp (LA) (1997) f Frequently flooded swamp (SC) ------1887 Muzika et al. (1987)
Maurepas Swamp locations (this study)
Relict Sites 11.68 g 179.2 143.3 e,g,h 322.5 g
Degraded Sites 4.0 g 78.0 66.4 e,g,h 144.4 g
Throughput Sites 23.26 g 435.7 301.4 e,g,h 737.0 g
Total Average 12.65 g 203.8 155.6 e,g,h 359.4 g a NPP = net primary productivity = litterfall + stemgrowth b Trees defined as > 2.54 cm DBH (diameter at breast height) c Cypress, Tupelo, Ash only d Litterfall does not include woody litter e Trees defined as > 10 cm DBH f All values are presented as averages of two replicate plots in two consecutive years g Averages of 3-6 sites with 2 sub-stations each h Cypress, Tupelo, Ash, Maple, and Blackgum, where present
63 List of Figures
Figure 1. The Maurepas swamps rim the margin of Lake Maurepas in southeastern Louisiana, and are bounded by urban development to the North, West, and South. Twenty sites were selected to represent the three major habitat types: Throughput sites (green), Relict sites (yellow), and Degraded swamp sites (red).
Figure 2. Results of multinomial logistic regressions classifying three a priori habitat types by maximum observed soil salinity and annual cypress and tupelo litter production. Clear separation occurs between Throughput and Degraded sites with some Relict sites sharing attributes with each.
Figure 3. The average observed soil salinity in the Maurepas swamps was greatly elevated during a severe drought in 1999 - 2000, then declined gradually through 2003 and increased due to drought in 2006. This effect was greatest at the Degraded sites located near Pass Manchac, which is the main salt water conduit into the system.
Figure 4. Soil bulk density (g cm-3), light penetration (%), and basal area of trees (m2 ha-1) summed over each 625 m2 plot for each of the three habitats. Degraded sites have the weakest soils, and the highest light penetration due to mortality of trees. Letters above bars indicate Bonferroni-adjusted significant differences
Figure 5. Cumulative percent mortality occurring in the three habitat types over time. Mortality increases linearly from 2000 – 2006 and is highest for ‘Other’ species and lowest for baldcypress (Taxodium distichum).
Figure 6. Results of nutrient enrichment experiment with and without herbivore exclusion cages. The 1X treatment simulates a Mississippi River re-introduction discharge of 42.5 m3 s-1 and a loading rate of 11.25 g N m-2 year-1. The 2X treatment doubles that loading rate and the 2X biannual treatment applies the timed-release fertilizer in early spring and again in mid- summer.
Figure 7. Annual herbaceous production, wood production, and litter production from 2000 – 2006 for the three habitat types. In general, the trees and ground cover followed inverse patterns through time with production increasing for herbaceous vegetation and decreasing for trees.
Figure 8. The interaction (F4,651 = 17.43, p < 0.00001) between species grouping and habitat type for total (leaf plus wood) production. Baldcypress production dominates in Throughput and Degraded habitats, but not in Relict habitats.
Figure 9. Overall (herbaceous plus tree) annual primary production averaged across habitat types from 2000 – 2006 with trees fluctuating between 200 – 400 g m-2 year-1 and ground cover showing a linear increase.
64 Figure 10. Overall tree and herbaceous production for each of the twenty sites was measured each year from 2000 - 2006. The twenty sites were grouped into three habitat types (Throughput, Relict, and Degraded) and analyzed using nonmetric multidimensional scaling (NMS). Axis 1 separates Throughput sites (the most treed sites) on the left from Degraded (marsh-like) sites on the right, with Relict forming a tree-herbaceous gradient (shown on top). Tree production is highest in Throughput sites (shown in middle). Herbaceous production is highest in Degraded Sites (shown in bottom). Numbers 0-6 represent years 2000 to 2006. Each year is represented within each habitat type.
Figure 11. Percent of midstory species wind thrown by the 2005 hurricanes (y-axis) across different basal areas of baldcypress - water tupelo canopy trees. Wind throw increases dramatically when basal area of canopy trees decreases below about 30 m2 ha-1. Points on x- axis below 30 m2 ha-1 have no midstory trees left to lose.
Figure 12. Average number of individuals of baldcypress, water tupelo, and ‘Other’ (mostly swamp red maple and green ash) species at each habitat type. Hatched areas show number of wind thrown midstory trees, demonstrating that Throughput sites, with the highest number of trees in the ‘Other’ grouping, suffered very low mortality from the 2005 hurricanes.
Figure 13. Photo of wetlands that can absorb storm surge as well as obstruct flow. 2D representation of this physical set up in the model underestimates the role of wetlands in storm- surge reduction.
Figure 14. Nodes elevated to keep surge level below them and force surge to flow around. In a highly dense domain this technique could be used to represent cypress swamps in the model. Resulting surge flow vectors are shown fig 3 and 4.
Figure 15. Flow vector around elevated nodes (top) and regular 2D model nodes (bottom). Flow vectors change direction due to obstructions suggesting a potential surge flow reduction.
65
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67 68 69 70 71 72 73 74 2D Stress: 0.02 Type Relict 0 Throughput 2 3 Lake 0 2 2 3 1 1 3 4
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Figure 13.
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Figure 15
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80 Mitigating the Spread of Zebra Mussels into Wetlands from Mississippi River Diversions. William F. Font
Abstract
The invasion of Louisiana wetlands by exotic zebra mussels via Mississippi River diversions is a real threat that has negative implications for both the environment and economic interests. Surveys are being conducted to determine if zebra mussels have already invaded wetlands or have the potential to invade at some future time. An assessment of potential biological control agents such as parasites, predation, and competition will aid in determining if the spread of zebra mussels can be mitigated.
Primary Objectives
If one were to select a poster child to represent alien species, the zebra mussel, Dreissena polymorpha, might be a good choice. The zebra mussel epitomizes an exotic invader that conforms to the definition of an aquatic nuisance species. Furthermore, although most Americans are notoriously ignorant of, or indifferent to, the consequences of exotic species, knowledge of the zebra mussel’s harmful ecological and economic impacts is widespread outside of the scientific community.
The main objective of this research is to determine if the zebra mussel has dispersed or has the potential to disperse in Louisiana from the Mississippi River into adjacent wetlands. Correlated objectives include documentation of the current geographic distribution of zebra mussels in aquatic habitats in south Louisiana in general, and with particular emphasis placed upon its occurrence in the Lake Pontchartrain – Lake Maurepas estuary. This study also will determine if biological factors exist that might mitigate the spread of zebra mussels.
Among these biological control factors, the primary emphasis will be placed upon documentation of the presence of parasites that are already present in Louisiana wetlands that have the potential to infect zebra mussels and impede their dispersal. The major source of parasites that might control the spread of this alien species of mussel are parasites of native mussels that presently occur in Louisiana wetlands. The native mussels species that stands out as the most promising candidate is Conrad’s false mussel, also known as the dark mussel, Mytilopsis leucophaeta because it is the sister species (i.e. its closest relative) to the zebra mussel. Among the various taxonomic groups of parasites that have the potential to both infect and control populations of mussels, digenetic trematodes represent the parasites that are most likely to be effective. Digenetic trematodes, commonly known as flukes, almost invariably use molluscs as first intermediate hosts in their life cycles. Although most trematodes utilize snails as first intermediate hosts, some species of flukes parasitize members of the Class Pelecypoda (=Bivalvia) which includes, clams, mussels, oysters, and their relatives. Of greatest importance to their potential role as control agents, the trematode life cycle stages that infect molluscs, sporocysts and rediae, are almost invariably parasitic castrators, that is, they totally
81 destroy the reproductive ability of infected hosts. For this reason, this group of parasites offers the greatest promise to serve as a biological agent that mitigates the spread of zebra mussels from the Mississippi River into Louisiana wetlands.
Standard parasitological techniques will be employed to investigate host – parasite relationships of trematode species that have the potential to serve as biological control agents. Surveys of native mussels will be conducted to determine whether they are infected with trematodes and to document rates of infection (i.e. prevalence of parasitized mussels). Life cycle studies will be conducted to determine second intermediate hosts and definitive hosts of these trematode species. (A definitive host is the host in which the parasite becomes an adult. The parasite reaches sexual maturity and produces eggs.) Surveys of prevalence and abundance in definitive hosts will be made. Discovery of the definitive hosts of these parasites is critical for two reasons. First, microscopic examination of adult trematodes parasitizing definitive hosts is essential for determining the specific identity of parasite species. Second, adult trematodes serve as the source of eggs containing miracidia which represent the life cycle stage that is infective for mussels. To complement field studies of parasite distribution, as time permits, an attempt will be made to infect mussels in the laboratory by experimentally exposing them to trematode miracidia.
Other biological factors that will be addressed on a more limited basis that may be relevant to the spread of zebra mussels include potential competition between native mussels and zebra mussels and predation of mussels by vertebrate and invertebrate predators. Field studies of competition will be initiated by documenting what species of native mussels occur in the Lake Pontchartrain – Lake Maurepas basin and determining the distribution of these mussels. Field studies of actual competition are predicated upon finding zebra mussels in wetlands where they occur syntopically with native mussels. Field observations of potential predators of mussels will be recorded. The study of vertebrate predators will focus mainly on fishes that have been reported as molluscivores such as red ear sunfish and drum. Fish will be captured and stomachs and intestines will be examined for the presence of shells of native mussels as well as zebra mussels. Similarly, invertebrate predation will be documented by examining the gut contents of crawfish and crabs for the presence of mussel shells.
Results
Extensive surveys of the geographic distribution of mussels in Louisiana wetlands have been conducted in the past year and have documented the occurrence of several species of freshwater and brackish water mussels. These mussels are potential competitors of zebra mussels and also serve as hosts for parasites that may infect zebra mussels. Freshwater mussels that were collected include several species in the family Unionidae as well as species of Sphaerium (Sphareriidae) which are native to Louisiana, and one exotic species, Corbicula fluminea, which has been introduced from the Orient. Brackish water mussels that were collected in the Lake Pontchartrain basis include Mytilopsis leucophaeta, Rangia cuneata, and Geukensia demissa. With two exceptions, zebra mussels have not yet been detected in the survey work is still underway. In the first exception, examination of the mussels shells
82 removed from cooler units located the CLECO electrical generation station on the Charenton Drainage and Navigation Canal near Baldwin, Louisiana revealed the presence of several species of mussels including two specimens of zebra mussels, Dreissena polymorpha. Following this discovery, an extensive survey of Bayou Teche, which is connected to the Charenton Canal was conducted. No zebra mussels were found in the bayou upstream of the CLECO station, indicating that the spread of zebra mussels into aquatic habitats in that geographic area is not extensive. The second exception was the presence of a single specimen, tentatively identified as a zebra mussel collected in Bayou St. John, New Orleans. Because only a single specimen of zebra mussel was collected at that site among several hundred specimens of Conrad’s false mussel, revisitation of that site is necessary before the presence of zebra mussels in Bayou St. John can be confirmed. Particular attention was paid to conducting zebra mussel surveys in the Bonnet Carre Spillway and Davis Canal because these are existing Mississippi River diversions that have the greatest potential of introducing zebra mussels from the river into adjacent wetlands. No zebra mussels were found in either of these two diversions, although its native sister species, Conrad’s false mussel was abundant in the Bonnet Carre spillway.
Much of the survey work conducted during the past year has focused upon the documentation of the geographic distribution of Conrad’s false mussel because, as the sister species of zebra mussel, this native species and its parasites are likely to have the greatest impact on the exotic mussel. Conrad’s false mussel has a broad geographic range in the Lake Pontchartrain – Lake Maurepas basin. We have collected this species from the eastern border of Lake Pontchartrain where we also found the highest salinities, to the western edge of Lake Maurepas were salinity was lowest. False mussels were collected in the artificial canal paralleling I-55 that was dug to facilitate construction of the elevated portion of the interstate. The salinity in the canal near its terminus south of Ponchatoula was 0.3 ppt, approaching freshwater, and false mussels were collected at that site. Conrad’s false mussel is abundant in Pass Manchac near the Turtle Cove Environmental Research Station, and that site has been selected as a principal study site.
Survey of trematode parasites of Conrad’s false mussel has thus far revealed the presence of two species that appear to be new to science. Life cycle studies are underway using cercariae, formed in sporocysts and rediae that parasitized the mussels. One of these species possesses a trichocercous cercariae that penetrated and infected naked gobies, Gobiosoma bosc that were exposed to it in the laboratory. The second trematode species infecting false mussels has a cystocercous cercariae and naked gobies that ate these cercariae in the laboratory became infected. In examining naked gobies from the site where infected false mussels were collected, we found both of these trematodes parasitizing these fish hosts. The first species has been identified as an undescribed species of Lasiotocus (Family Monorchiidae). It is a highly unusual species in that although it encysts in the musculature of the fish, it reaches sexual maturity precociously and produces eggs. A search is currently underway to determine if a true definitive host containing unencysted adults can be found. The second species of trematode also encysts as a metacercaria in naked gobies. Morphological examination of this species places it near the genus Diplangus in the family Zoogonidae. A search for the definitive host for this second species is also underway. The discovery of the definitive hosts of these two species is important because they serve as sources of eggs
83 containing miracidia that are infective to false mussels, and potentially to zebra mussels as well if they invade this estuary. Our further survey work has found these two parasites in naked gobies from two other areas of the Lake Pontchartrain basin, near Slidell, and near the mouth of Bayou Lacombe in the Big Branch National Wildlife Refuge.
At Big Branch, we have recently discovered that the rainwater killifish, Lucania parva is infected with adult specimens of yet another species of monorchiid trematode. Microscopical examination of these parasites are currently in progress, and thus far the species can only be tentatively identified as a member of the genus Monorcheides or a closely related genus. Because monorchiid trematodes often use mussels as first intermediate hosts (as we have documented for Lasiotocus sp.), we are searching for mussels in the Big Branch wetlands that may be the host of Monorcheides sp. and thus be an additional biological control agent if zebra mussels invade this area.
Future Plans
A continuing effort will be made to extend our survey for zebra mussels in Louisiana wetlands. We will examine areas of the Lake Pontchartrain – Lake Maurepas basin that we have yet to visit and examine areas where our previous survey efforts require more intensive investigation. As one specific example, survey work in the Davis Canal Diversion will be extended into the Lake Cataouatche wetlands where more suitable habitat for mussel establishment exists.
We have recently set out PVC pipes as artificial substrate for colonization of zebra mussels and false mussels. After waiting an appropriate time for settlement and attachment of mussels we shall retrieve these substrates and examine them in the laboratory for signs of colonization. We shall also set out additional artificial substrates in aquatic habitats most susceptible to zebra mussel invasion, including Bonnet Carre Spillway, Davis Canal, and Harvey Canal on the westbank of New Orleans.
An additional technique will be employed to search for mussels. We shall sample water bodies using plankton nets in order to detect the veliger larva and postlarval stages of zebra mussels and other mussel species as they emerge during the reproductive season. The documentation of veliger larvae in habitats such as Davis Canal will be conclusive proof that dispersal of zebra mussels into Louisiana wetlands is indeed occurring. This documentation is significant in that it provides evidence that even if establishment of zebra mussels has not yet occurred, establishment at some time in the future may take place. Specifically, even though the colonization may be precluded at the present time by some environmental factor such as high water temperature of wetlands during summer months, the zebra mussels may, in time, evolve a higher temperature tolerance that may make colonization a reality.
In addition to continuing and extending our survey for zebra mussels, we shall simultaneously continue our survey of biological factors, particularly parasites that may control the present or future spread of zebra mussels into wetlands. Life cycle studies of the new species of Lasiotocus and cf. Diplangus sp. will be broadened, searching for definitive hosts,
84 and developing techniques to harvest parasite eggs in order to infect mussels in the laboratory. Studies on the host specificity of Monorcheides sp. will be conducted to determine whether additional hosts beyond rainwater killifish may harbor the egg producing stage of the life cycle and thus further extend the importance of this trematode as a potential biological control agent. We shall also attempt to determine the first intermediate host of Monorcheides sp. in order to determine whether, as is true for Lasiotocus sp. and Diplangus sp., that host is Conrad’s false mussel, or perhaps another species of mussel that occurs in the Big Branch Wildlife Refuge.
If zebra mussels are found syntopically with false mussels, we shall monitor natural and artificial substrates to determine whether these two species compete for habitat and what the outcome of that competitive interaction might be. We shall also attempt to collect fish and crustacean host from wetlands to conduct a trophic analysis and assess their role as mussel predators that might limit the spread of zebra mussels in wetlands.
Information Transfer
1. The overall goal of this project is to assess the actual or potential threat of dispersal of the exotic zebra mussel, Dreissena polymorpha into Louisiana wetlands. Related to that main goal, the Lake Pontchartrain – Lake Maurepas basin will be surveyed to see if potential biological control agents occur naturally in aquatic habitats that can control the spread of zebra mussels. Examples of biological control agents include competition with species of native mussels, predators that consume mussels, and parasites of native mussels that can infect invading zebra mussels.
2. There exists extensive documentation that the zebra mussel can be categorized as an aquatic nuisance species. The invasion of the United States by this alien species has already caused extensive economic damage to human infrastructure such as industrial equipment, navigation aids, water cooling systems etc. that are located in bodies of water that have been colonized by zebra mussels. The ecological impact of this species on native fauna such as unionid clams has been shown to be severe and is of great concern to wildlife management agencies.
3. Maintenance of our wetlands in their natural state is threatened by the invasion of alien species. Sustainability of wetlands requires that native species are protected from threats imposed by exotic species. Whether zebra mussel invasion of Louisiana wetlands has already occurred or may take place at some future time, it is imperative that we are prepared for this invasion. Adequate preparation involves a more complete knowledge of our native fauna, and which components of that fauna may serve as biological control agents that can mitigate the spread of this exotic species.
4. The threat of zebra mussel invasion impacts all parishes in south Louisiana. Because of the extensive interconnectedness of our waterways and the documented presence of zebra mussels in our major rivers (i.e. Mississippi River, Atchafalaya River), the potential spread of this exotic species affects all geographic regions of south Louisiana. Because the potential
85 negative impact of zebra mussel dispersal affects both the environment and the economy, there are numerous government agencies that are needful of this information. Both federal and state agencies that deal with wildlife or conservation will benefit from the results of this study. Examples of such agencies include: U.S. Fish and Wildlife Service, Louisiana Department of Wildlife and Fisheries, Department of Environmental Quality. Many industries that use Mississippi River water have already been severely impacted economically by zebra mussels. State and federal agencies that are concerned with providing assistance to or regulating these industries are impacted by this invasive threat. Commercial and recreational fishermen may have boats, motors, and equipment encrusted by zebra mussels and be negatively impacted.
5. An example of beneficial communication with an impacted industry has already occurred as a result of the first year of this study. In my survey work for the presence of zebra mussels along Bayou Teche in southwest Louisiana, I had an extensive conversation (followed up with additional communication via email) with Mr. Peter Trimble, a supervisor at the CLECO power plant near Baldwin, LA regarding the threat of zebra mussels and the impact that they might have on his power station. Because of my discussion with him, he mailed to me the mussels that had colonized the coolant water intakes at the facility. Among those mussels, I found specimens of zebra mussels. I informed Mr. Trimble of this discovery and made him aware of its potential impact on his power plant. I think that this serves as a good example of the mutually beneficial relationship that can exist when scientists communicate directly with people in industry or government and work together on a common problem.
There are clear management implications that result from this study. First, it should be made evident that this study is not designed to formulate evidence that would result in the closure of Mississippi River diversions. Clearly, the positive benefits of diversions of freshwater and sediments into wetlands far outweighs the negative impact of introducing zebra mussels into those wetlands. The key point is that we must be aware that the release of zebra mussels via river diversions is inevitable and the mussels either have the present capability of surviving in those wetlands or may evolve that capability at some time in the future. Therefore, we can best prepare for such an invasion by knowing what potential biological control agents exist in the wetlands, and if possible, to determine how these naturally occurring agents may be further augmented in an effort to mitigate the spread of exotic zebra mussels.
86 Development of an Index of Biological Integrity for the Lake Pontchartrain Basin Wetlands Janice Bossart (PI) and Colin Jackson (co-PI)
Abstract
This collaborative study is a comparative, joint analysis of the benthic invertebrate diversity, microbial activities, and water chemistry at a strategic array of sites in the Western Lake Pontchartrain Basin (WLPB). Study sites have been selected to span and anchor both ends of a wetlands disturbance gradient. Their survey will be used to identify consistent, reliable biological indicators (metrics) and determine how these correlate with water quality. Survey data will ultimately allow us to establish a detailed narrative of what constitutes non-degraded versus degraded swamp habitat in the WLPB. The overriding objective of our study is to use these comparative data to develop the first ever biologically-based management tool (an Index of Biological Integrity) for use by conservation managers for rapid bioassessment of Southeastern Louisiana’s cypress swamps.
Primary Objectives • Identify sample sites in the Joyce Wildlife Management Area and Lake Maurepas Wetlands System that form an intact to degraded habitat continuum. • Collect benthic macroinvertebrate, sediment microbial, and water chemistry samples every 4 weeks for one year from the identified sites. • Characterize invertebrate community diversity, microbial activity levels, and water chemistry profiles at each sampling site. • Quantify the relationships among community diversity, microbial activities, and measurements of water chemistry, i.e. dissolved oxygen, pH, salinity, and temperature. • Identify which biological attributes (metrics) show quantitative and predictable responses to measured changes in water chemistry. • Establish the reference set of baseline conditions (biological and physical) that discriminate intact versus intermediate versus degraded swamp habitat. • Establish scoring criteria for each biological metric for development of an IBI.
Results
In this first year of the project, primary project activities have emphasized the 1) logistics of hiring and training of field and laboratory personnel and student workers, 2) boat operation safety and training, 3) scouting and identification of specific field sites, 4) testing, proofing, and implementation of a year-long sampling scheme of multiple sites, and 5) successful transport of sediment samples to co-PI Jackson at The University of Mississippi. Specifically,
On-the-ground scouting forays to potential swamp sites were undertaken to identify the specific array of sites for ongoing and regular sampling. A total of seven primary sites have been identified, four at Joyce Wildlife Management Area (JWMA) and three in the Lake Maurepas Wetlands System (LMWS). Three sub-sites within each of the primary sites have
87 additionally been identified to provide information on within site variation. Three of the JWMA sites, Kleibert’s Ditch, Mainline Boat Trail, and Swamp Boardwalk, represent relatively intact cypress-tupelo swamp but additionally are characterized by slight differences in salinity. The fourth, Three Mile Marsh, is a natural marsh that receives affluent from the Hammond sewage treatment plant. Survey of this natural marsh will provide valuable comparative data with the derived marsh habitat that occurs in severely degraded areas of Lake Maurepas. The three sites in the LMWS represent intact (Alligator Island), partially degraded (Blind River), and severely degraded (Ruddock) swamp habitat.
The on-going, regular sampling was initiated at the 12 JWMA sites (4 primary x 3 sub-sites) in May 2007. To date, more than 1700 benthic invertebrate specimens have been collected (Figure 1). Nearly twice as many specimens have been collected from 3-Mile Marsh and Keibert’s Ditch versus Mainline Boat Trail (Figure 1).
Figure 1. Total number of benthic invertebrates collected from each of the JWMA sites.
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0 3-Mile Marsh Swamp Mainline Kleibert Site
The large number collected at Kleibert’s Ditch mostly results from a single collection date, October 2; the number collected at Three-Mile Marsh however was almost always as great as or greater than the number collected at the other sites on any given date (Figure 2). Given Three-Mile Marsh receives affluent from the Hammond sewage treatment plant, this result could reflect positive correlation between high nutrient levels and number of invertebrates collected. Taxonomic identification of invertebrate samples is just beginning, but Crustecea, Mollusca, Insecta, Annelida, and Nematoda are the major groups represented after preliminary sorting.
88 Figure 2. Average # of specimens collected by sampling date at the JWMA sites.
100 T Three Mile Marsh S Swamp Boardwalk M Mainline K 80 K Kleiberts
60 T 40 T M
T S S K 20 T T T Average # collected MKS S S S K K K M S M M M MK 0 T May 23 Jun 4 Jun 25 Jul 17 Aug 6 Sept 7 Oct 6 Date
Sediment samples collected at each of the sites have been assayed for microbial activity levels. These included activities of seven different microbial enzymes involved in organic matter decomposition (beta-glucosidase, cellobiohydrolase, beta-xylosidase, phenol oxidase, lignin peroxidase) and nutrient cycling (acid phosphatase, N-acetyl-glucosaminidase). Beta- glucosidase activity has generally been highest at the Swamp Boardwalk site, particularly for the July samples (Figure 3). Enzyme activities at the other sites were much lower. These tended to track each other at Mainline and Three Mile Marsh, and to remain relatively constant over the summer at Kleibert’s Ditch (Figure 3).
Figure 3. Beta-glucosidase activity in wetland sediments (open squares = Swamp Boardwalk, open triangles = Kleibert’s, closed squares = Mainline, closed triangles = 3-Mile Marsh).
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Phosphatase activity at Three Mile Marsh and Kleibert’s Ditch has been similar and relatively stable over the summer (Figure 4). Phosphatase activity was much more variable at the Swamp
89 Boardwalk and Mainline boat trail sites, and these activity levels tended to fluctuate in different directions.
Figure 4. Phosphatase activity in wetland sediments (open squares = Swamp Boardwalk, open triangles = Kleibert’s, closed squares = Mainline, closed triangles = 3-Mile marsh).
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Activities of the hydrolytic enzymes involved in organic matter decomposition (beta- glucosidase, cellobiohydrolase, beta-xylosidase) have thus far been closely correlated with each other (r = 0.81 to 0.96), and have tended to be higher at the Swamp Boardwalk site. These activities have also been correlated with N-acetyl-glucosaminidase activity (r = 0.81 to 0.93), likely reflecting the dual role of N-acetyl-glucosaminidase in both organic matter (chitin) decomposition and nitrogen cycling. Activities of the hydrolytic enzymes have only weakly correlated with phosphatase (r = 0.65), likely due to overall higher microbial activity that increases activity of all enzymes. Patterns in the activities of the oxidative enzymes (phenol oxidase, lignin peroxidase) are less clear at this point, and have often been below detection limits. Both of these enzymes have tended to have higher activity at the Three Mile Marsh site; however this trend has not been statistically significant given the limited data set to date.
Future Plans
Sampling of all JWMA sites is slated to continue through May 2008. Sampling at the Lake Maurepas sites will continue through August 2008 because of the later start at these sites. Sample analysis will continue until completion. Microbial activity analyzes are well underway and anticipated to be competed by end December 2008. Taxonomic identification of the benthic invertebrate samples has just been initiated and the characterization of these communities is a major goal for coming year.
Technology Transfer
The overall goal of our project is to provide a scientifically based, management tool for use by conservation stakeholders to assess the condition/health of Louisiana’s cypress-tupelo swamps
90 in the Western Lake Pontchartrain Basin (WLPB). This management tool (an Index of Biological Integrity (IBI)) will be developed based on biological criteria (microbes and benthic invertebrates) and as such will be able to capture the complexity inherent in ecological systems that is not provided by traditional, point-in-time chemical assessments.
Forested wetlands are a predominant habitat in the WLPB. Reversing their loss and degradation has been identified by state and national stakeholders as a chief conservation priority as ecosystem sustainability is vitally linked to their health. Current efforts to evaluate and track the condition of these key ecosystems are stymied by the absence of ecologically based assessment tools. Development of an IBI specific to cypress-tupelo swamps will give stakeholders a “yardstick” by which to measure swamp condition and a powerful tool for compiling the critical ecological data needed by managers and decision-makers. Development of an IBI specific to the WLPB additionally links directly to the imminent restoration activities planned for the Basin. This biologically-based management tool will let stakeholders easily track, for example, changes in the health of Maurepas Swamp resulting from the Mississippi River Freshwater Diversion Project.
Our target groups, microbes and benthic invertebrates, are both superlative and proven indicators of, and directly linked to, ecosystem health. Their survey will provide information on swamp condition over both the short (days-months; microbes) and mid (months-years; invertebrates) term. This will allow decision-makers to more easily assess real time and ongoing changes in these ecosystems that might occur in response to natural events, such as hurricanes, or anthropogenic impacts, such as freshwater diversions or increased North Shore development and pollution. Corrective measures could then be implemented earlier rather than later, resulting in a reduction in the breadth and impact of the disturbance.
91 Determining the Potential for Algal Bloom in Lake Maurepas: Effects of Changing Nutrient Load from Freshwater Diversion and Changes in Human Population
Abstract The concentrations of nutrients in Lake Maurepas are measured on an approximately biweekly basis. The surface temperature of the lake and its water clarity based measurements with a Secchi disk are completed at 9 sites throughout the lake by boat. Water samples are returned to Southeastern Louisiana University where the levels of phosphate and silicate are determined spectroscopically. The pH and nitrate, sodium and chloride ion concentrations are determined potentiometrically. Algae content is determined by HPLC analysis of photopigments in algal cells removed from lake water by filtration. Light microscopy is used to identify phytoplankton species.
Primary Objectives Monitor the concentration of nutrients in Lake Maurepas over the course of the project at 9 locations. Nutrients of interest are phosphate, silicate, and nitrate. Additionally, water surface temperature, water clarity, pH, sodium, chloride, and nitrite levels are monitored. Monitor phytoplankton levels in Lake Maurepas over the course of the project at 9 locations. Phytoplankton are identified by light microscopy. Additionally, HPLC analysis of pigments in phytoplankton is used to classify the types of algae present and to quantify their levels in each sample. Determine which nutrients most strongly influence the amounts and types of phytoplankton present in Lake Maurepas. Determine the nutrient levels that would lead to significant algal growth.
Results Overview: During the first year of this work, temperature, pH, and phosphate levels were successfully recorded during 6 sampling trips from June 8, 2007 to September 9, 2007. Nitrate levels were also measured; however, the concentration of nitrate in Lake Maurepas was below the detection limit for the ISE method for almost all samples. In the future, nitrate and nitrite levels will be measured using a significantly more sensitive spectroscopic method. Silicate levels were determined only for the samples collected on September 9th and will be measured for all future samples. Filtered algae samples were submitted to Dr. Jay Pinckney at the University of South Carolina for processing in September, but results have not yet been communicated. Identification of phytoplankton by light microscopy is also progressing; however, changes are being made in the current procedure to enable Dr. Sophia Passey at the University of Texas at Arlington to provide more accurate identification. Sampling: In April of 2007, 3 samples were taken within 500m of each other at each of 9 locations in Lake Maurepas. No significant differences in nutrient levels or water clarity were observed in the 3 samples from single locations. In order to streamline the monitoring process and make the analyses more efficient with respect to the time spent by undergraduate research
92 students, only one set of samples will be taken at each location. The locations include the four primary inlet streams (Amite, Blind, and Tickfaw Rivers, and Reserve Canal) the two primary outlet streams (Pass Manchac and North Pass), and three main lake sites near the center of the lake (table 1 and figure 1). Each site is located using a Magellan Tracker GPS unit. The latitude and longitude for each site is listed in table 1. Based on the initial measurements of more widely dispersed samples, variations in the sampling location within this limited area will not adversely affect results. At each location, temperature is immediately measured. A grab sample is obtained using a 2.2L water sampler that was fully submerged at the surface and a portion is transferred to a 1L glass bottle that is stored in a cooler for analysis at Southeastern. A second grab sample is obtained in a 500ml plastic bottle that is also stored in the cooler for silicate analysis in the laboratory. All samples are placed in a refrigerator until analyzed.
Table 1. Sampling Locations 30°16.84±0.02N North 30°18.64±0.07N Manchac 90°24.84±0.01W Pass 90°25.25±0.02W 30°20.47±0.04N 30°17.94±0.02N Tickfaw Amite 90°28.51±0.03W 90°33.35±0.01W 30°12.46±0.01N 30°10.35±0.02N Blind Reserve 90°35.20±0.04W 90°32.94±0.01W 30°13.09±0.02N 30°16.23±0.02N Midlake1 Midlake2 90°31.91±0.01W 90°31.69±0.02W 30°16.38±0.02N Midlake3 90°28.25±0.03W
Figure 1. Lake Maurepas Sampling Sites
Analyses: HPLC Analysis of Phytoplankton: 300ml of water from each site are immediately filtered following each sampling trip onto two Whatman 934AH glass fiber filter papers. The filter papers containing phytoplankton are sealed in aluminum foil and stored in ziplock bags at – 70°C. After approximately 5 sampling trips, the filters are shipped on dry ice to Dr. Jay
93 Pinckney at the University of South Carolina for HPLC analysis. The first samples were shipped in September and we are awaiting results of these analyses. Analysis of pH: The pH’s of the natural water samples were determined potentiometrically. Samples taken near inlet streams had the most acidic pH and show greater site-to-site variability than main lake and outlet stream sites. Analyses of water taken near inlet streams also show the widest pH variability over time at single sampling locations. The changes in pH, however did not show any trend over time between sites near inlet streams. While the main lake and outlet stream sites did not show a specific trend, the pH levels at these locations did track each other, rising and falling at the same times, particularly over the first six weeks of the study. Over the study period, pH was overall stable ranging from a minimum of 6.6 at the Amite River on June 22, 2007 to a maximum of 7.6 at the mid-lake #3 site on June 8, 2007. The pH results are summarized in figure 2.
8 8
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5.5 5.5
5 6/1/07 6/21/07 7/11/07 7/31/07 8/20/07 9/9/07 5 6/1/07 6/21/07 7/11/07 7/31/07 8/20/07 9/9/07 M anchac North Pass M idlake 1 M idlake 2 M idlake 3 Reserve Tickfaw Amite Blind
Figure 2: pH at main lake and outlet sites (left) and inlet sites (right)
Analysis of Phosphate: Phosphate concentration is determined based on the absorbance of phosphomolybdic acid (a colored complex formed by the reaction of molybdate, stannous chloride, and phosphate) at 690nm. Initially a simple single beam spectrometer was employed; however to improve sensitivity and reproducibility, it was replaced by a double beam spectrometer. Main lake and outlet stream sites had the lowest average levels of phosphate over the initial study period ranging from 0.11 ppmP for the mid-lake #3 site to 0.15 ppmP at Pass Manchac. In contrast, phosphate levels ranged from 0.18 ppmP (Tickfaw River) to 0.23 ppmP (Blind River) at the inlet stream sites. The variation in phosphate levels for single sampling sites does not show differences between inlet sites and main lake and outlet sites. For phosphate, the largest range of phosphate levels are observed at Reserve Canal with an average concentration of 0.22±0.10 ppmP and ranging from 0.42 ppmP on June 8, 2007 to 0.17 ppmP on August 3, 2007. The smallest variation in phosphate levels are also observed at one of the inlet streams, the Blind River, with an average concentration of 0.23±0.03 ppmP and ranging from 0.26 ppmP on June 8, 2007 to 0.19 ppmP on September 10, 2007. Phosphate results are summarized in figure 3 below.
94 0.5 0.5
0.45 0.45
0.4 0.4
0.35 0.35
0.3 0.3 0.25 0.25 0.2 0.2 0.15 0.15 0.1 0.1 0.05 0.05 0 6/1/2007 6/ 21/2007 7/ 11/2007 7/31/2007 8/20/ 2007 9/9/ 2007 0 6/1/2007 6/ 21/2007 7/ 11/2007 7/31/2007 8/20/ 2007 9/9/ 2007 Midlake 1 Midlake 2 Midlake 3 Manchac Nort h Pass Reserve Tickfaw Amite Blind
Figure 3: Phosphate at main lake and outlet sites (left) and inlet sites (right)
Light Microscopy: Water samples from each site are centrifuged to concentrate phytoplankton into a smaller volume prior to examination under light microscopy. Typical magnification is 40x or 100x. More than 500 digital photographs have been stored thus far and most have been copied to CDs and shipped to Dr. Sophia Passey at the University of Texas at Arlington. After examining the photographs, Dr. Passey requested that permanent wet mount slides be prepared for each site. Additionally, samples are digested to remove organic content from algal cells leaving diatom fristules for microscopic examination. Meltmount is used to prepare permanent dry mounts of the diatom fristules. These slides will be shipped to Dr. Passey in late September or early October.
Other Analyses: The level of nitrate in Lake Maurepas was determined to be below the detection limit offered by potentiometric detection with ion-selective electrodes for most samples. For this reason, spectroscopic analysis of nitrate and nitrite will be used instead for future samples. Silicate analysis has begun and satisfactory results have been achieved with a spectroscopic method.
Future Plans Continued Monitoring: Monitoring at the nine sampling sites will continue throughout the project. Preparation of filtered algae samples for HPLC analysis at University of South Carolina will continue as previously. Analysis of pH, phosphate, and silicate will continue in the same manner as employed during the first portion of the study. Nitrate analysis will be changed to a spectroscopic method and analysis of nitrite and chlorophyll a will be added.
Nutrient Enrichment: During the next year, water samples will be returned to the laboratory and the nutrient levels will be adjusted to observe the effect on algal growth. Water samples will be enriched with phosphate, nitrate, and silicate and the concentration of algae will be measured after one week. The types of algae present before and after enrichment will also be examined.
95 Technology Transfer Goal Statement: This project will monitor the concentration of important nutrients (phosphate, nitrate, and silicate) and algal levels at nine locations in Lake Maurepas to identify nutrients most responsible for algal growth and control of the types of algae present. The project will study the effect of enhanced nutrient levels on algae in the laboratory and will examine both changes in the total algae concentration and the types of algae present in the nutrient enriched samples.
Rationale: The results from this project are potentially of interest to policymakers in several areas. First, a working knowledge of nutrient levels in Lake Maurepas and the likely effect of changing these levels will be of interest in determining the location and extent of freshwater diversions from the Mississippi River which is traditionally higher in nutrients than Lake Maurepas. Second, with increasing human population in the watershed feeding Lake Maurepas, existing water treatment facilities will be stressed. Knowledge of the nutrient levels in Lake Maurepas, particularly at inlet streams may be useful in determining which treatment facilities should be expanded and potential locations for construction of new water treatment facilities. Additionally, general water quality and the ability to predict the potential for algal bloom based on nutrient enrichment studies will be useful to persons and agencies interested in commercial and recreational fishing in the lake.
Impact: Lake Maurepas is bordered by Livingston, St. John the Baptist, and Tangipahoa Parishes. The drainage basin for the three primary inlet streams (Amite, Blind, and Tickfaw Rivers) includes Ascension, East Baton Rouge, East Feliciana, St. James, and St. Helena Parishes. Likely interested governmental agencies include the U.S. EPA, the U.S. Army Corp of Engineers, the Louisiana Department of Natural Resources, the Louisiana Department of Wildlife and Fisheries, and the Louisiana Department of Agriculture and Forestry.
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Information Transfer and Outreach Program for the Lake Pontchartrain Basin Research Program. Thais Perkins1, Robert Moreau2, Tiffany McFalls3, Denise Rousseau-Ford4
1Assistant Director/ Information Transfer Coordinator for PBRP 2Dr. Robert Moreau, Manager of Turtle Cove 3Tiffany Mcfalls, Southeastern Louisiana University 4Denise Rousseau Ford, Gulf South Research Corporation
Abstract
The last year has seen the development of an active in-house Information Transfer and Outreach program for the Lake Pontchartrain Basin Research Program (PBRP). The goal of this program has been to translate the knowledge gained in PBRP research activities to both (a) decisionmakers in the regulating agencies and communities and (b) stakeholders in the basin such as citizens and the news media. Ultimately, our goal is to ensure that the Program’s research is appropriately applied to current environmental and ecological issues and, in particular, to the effective management of the Pontchartrain Basin for human communities and the physical environment. This will be defined by the resulting reduction of environmental and economic damage to the basin and, in turn, the environmental and economic health of the stakeholders and communities of the Pontchartrain Basin.
Primary Objectives
Key objectives of the Information Transfer and Outreach program in the last year have been: 1. Creation of an Information Transfer and Outreach Plan; 2. Redevelopment of the existing website to include the learning styles of multiple audiences while enhancing the interactivity of the site and strengthening content; 3. Development of outreach tools (Research Highlights, Pontchartrain Basin Updates) 4. Creation of a Stakeholder Seminar Series with a stock presentation to be modified by presenters and booking of 4 presentation dates; 5. Employment of other communication tools to further the program’s objectives.
Initially conceived of as a two-year plan, the program was funded as a one-year plan and executed on that timetable instead.
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The purpose of the Information Transfer and Outreach Program is to ensure that the knowledge gained in the Lake Pontchartrain Basin Research Program’s (PBRP) research activities is disseminated widely to decisionmakers and technical professionals in the regulating and regulated communities as well as to other important stakeholders, the general public, and the news media. Both stakeholders and the general public include a variety of audiences vitally tied to the health of the basin such as: communities affected by the quality of the Pontchartrain Basin, the fishing industry, the forest products industry, the tourism industry, and the news media. Technical professionals, also considered stakeholders, would include technically- trained state and federal regulatory individuals as well as the scientific community. The goal is to ensure that the Program’s research is appropriately applied to current environmental and ecological issues and, in particular, to the effective management of the Pontchartrain Basin. Timely dissemination of research results to stakeholders and communities facing the changes brought about by both the hurricanes’ accelerated physical degradation of the basin and the potential degradation due to relocation along the north shore of Lake Pontchartrain is critical to achieving the goal of PBRP. Ultimately, the value of the fundamental research conducted by PBRP is defined by the resulting reduction of ecological and environmental damage to the basin, and in turn, to the environmental and economic health of the stakeholders and communities of the Pontchartrain Basin. Without information transfer and outreach to the stakeholders and communities, who are ultimately the end users, no degradation reduction is possible. Maximizing that information transfer and outreach requires active management within the Program.
Objective 1: Creation of an Information Transfer and Outreach Plan The Information Transfer and Outreach plan has pursued elements of the four objectives throughout the two-year proposed project on a one-year timeline. However, this work was proposed to include three phases: 1) continued establishment of the PBRP’s public profile in year one; 2) translation and dissemination of the Program’s current research products during year one through year two; and 3) compilation of the Program’s research accomplishments since its inception for broad dissemination in year two. An outreach program like this is dependent upon not just creating appropriate materials but establishing a network of organizations and individuals which can help to spread information quickly. As such, it needs time to grow.
Objective 2: Redevelopment of the existing website to include the learning styles of multiple audiences while enhancing the interactivity of the site and strengthening content In the past year, we reevaluated the existing PBRP website and revamped it to meet the learning needs and preferences of each of our core audiences. In the process, we incorporated interactivity into the site in the form of (1) the ability of the user to self-add their email address to a growing list of users, (2) a self-updating calendar of events such as scheduled seminars and (3) a search function. Users can also email PBRP with their questions and concerns about the Basin.
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Figure 1. Screenshot of PBRP’s new website design
Objective 3: Development of outreach tools (Research Highlights, Pontchartrain Basin Updates)
We have developed two tiers of printed publications for PBRP and one online publication:
1) PBRP Research Highlights: these are a 1-page information handout summarizing the research findings of particular PBRP projects, and are meant to facilitate peer-to-peer and decisionmaker communication. PBRP has developed a template and written 6 of these in a year’s time. They are as follows:
• Parasites as Indicators of Pollution | W. Font, M. Collins, and S. Temple • Effect of Wetland Degradation on Bird Communities | P.C. Stouffer and Jason A. Zoller • Use of Lake Maurepas Wetlands by Migrating Birds | P.C. Stouffer and Jason A. Zoller • Ecology and Restoration Potential of the Manchac Wetlands: Simulating a Diversion in the Maurepas Swamps | G. Shaffer, T. Perkins, D. Thomson, S. Howell, and S. Hoeppner • Ecology and Restoration Potential of the Manchac Wetlands: Effects of Contaminants upon Sunfish A. Cheek and B. Henry • Turtle Cove Experimental Marsh: Effects of disturbance and fertility upon the vegetation of a Louisiana coastal marsh. | T. Mcfalls, P. Keddy, G. Shaffer and D. Campbell
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2) PBRP Pontchartrain Basin Updates: these are 2-4 page brochures meant to address stakeholder concerns as expressed by the stakeholder group; ergo, they are not summaries of PBRP research but rather synopses of current environmental issues in the Basin. We have produced one of these thus far (Understanding the Environmental Impacts of Cypress Mulch), as they take far longer to develop a consensus upon content and dissemination.
3) 3) Our proposal stated that we would continue to produce our online newsletters; we have in fact decided to replace these with an email bulletin-type series of announcements to be more timely. These announcements are tiered as well to be more suitable to variable audiences.
Objective 4: Creation of a Stakeholder Seminar Series with a stock presentation to be modified by presenters and booking of 6 presentation dates;
One of the most direct lines of communication between our program and stakeholders in the basin is the traditional, face-to-face communication that comes with personal contact. In that tradition, we have developed a stock seminar entitled “Swamps to Savannahs: The Environmental Status of our Lake Pontchartrain Basin Ecosystems” that can be adapted for many different audiences (historical, gardening, birding, scientific, educational). We have scheduled four presentations at this time at libraries, plant societies, and museums on the northshore and have received funding from the Pontchartrain Restoration Program to continue this work over the next year. These seminars not only give a historical and ecological context to basin issues but also showcases the Program’s work and delivers research results to technical audiences in an interactive format. Stakeholders will be able to interact directly with the PIs and information transfer team, allowing stakeholders and PIs to benefit greatly. Stakeholders can have their questions and concerns addressed immediately during the seminar question and answer session as well as during the reception to be held after the presentations are complete. PIs will be able to develop and discuss research ideas with regulatory agencies so that PIs in the program develop research programs that address the issues on which regulatory agencies need the most information.
100 Finally, these seminars will be evaluated with traditional ‘sunrise sunset’ methods to evaluate our own efficacy.
Objective 5: Employment of other communication tools to further the program’s objectives.
(a) Radio: Our initial proposal envisioned developing collaborations with Southeastern Louisiana University’s other media outlets such as television and radio; we have developed a public service announcement for radio based upon our Pontchartrain Basin Update and will use those as a model for future radio spots. (b) Posters: Other traditional materials such as posters have been employed, such as the poster below, which was taken to the EPA 2007 Community Outreach Conference:
Figure 4: Poster created and displayed at EPA 2007 Community Involvement Conference
(c) Online Tools: Existing networking tools have been folded into the PBRP webpage, such as a Google Groups self-adding mailing list; use of the Google Calendars tool to present our seminar dates in calendar format; and a MySpace page to take advantage of the social networking tendencies of the 18-29 age bracket.
Future Plans
101 We have fulfilled this two-year proposal above and beyond its requirements on a one-year time frame. Our future plans for the program are first and foremost to secure future funding to extend our efforts; we have made small strides towards this goal with the funding of our seminar series grant with PRP, but that does little to extend the Information Transfer and Outreach program as a whole. In fact, we only now feel that we are poised, after a year of development, to reach the stakeholders of the basin. That being said, our future plans are to build upon the work we have done in many ways: • fleshing out the website with new projects; • creating Research Highlights as the recently funded PBRP projects come to completion; • creation of Pontchartrain Basin Updates concerning mitigation potential on the northshore and the use of sewage effluent to improve wetlands in the Basin; • encouragement of further interaction and collaboration amongst peers by interlinking websites; • development of a ‘virtual meeting room’ in which PI’s can interact with busy and far-flung decisionmakers that may not be able to meet physically on location; • further refine our seminar series and learn the information needs of stakeholders in the basin • more….
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