WETLAND
RESTORATION
Louisiana’s extensive
wetland loss threatens biodiversity, has made the state’s
coastal region vulnerable to flooding from storms, has made the
interior vulnerable to saltwater intrusion, and has reduced estuarine
nurseries and habitat. Together these have cast a mantle of economic
and social uncertainty. Louisiana Sea Grant encourages research
in restoration science and engineering to stop or reverse wetland
loss.
Nutrient
Dynamics and Primary Productivity at the Caernarvon Freshwater
Diversion
Day, J., Louisiana State University, Coastal
Ecology Institute
Diversion
of fresh water from the Mississippi River into deteriorating coastal
wetlands is a commonsense strategy for obtaining the nutrients
and sediment needed to restore those wetlands. However, if the
introduced water contains more nutrients than the wetlands can
use for plant growth, the excess nutrients may add to the hypoxic
condition that causes the persistent “dead zone” in
the northern Gulf of Mexico. Another concern is the possibility
that enrichment and dilution of waters in Breton Sound could stimulate
noxious algal blooms and shut down valuable oyster grounds. This
study will investigate the impact of freshwater diversions on
estuarine water quality and determine the effectiveness of coastal
wetlands in processing Mississippi River water before it enters
the Gulf of Mexico. The principal investigator will study the
water chemistry and phytoplankton productivity response of the
Breton Sound estuary to water introduced through the Caernarvon
diversion structure. Objectives include: determining how the introduced
river water changes spatial and temporal patterns of nutrients,
sediments and aquatic primary production in the estuary; determining
the capacity of this estuary to convert dissolved nitrogen compounds
into harmless nitrogen gas; determining the factors limiting aquatic
primary production, especially light nutrient concentrations,
with special reference to the relative proportions of inorganic
nitrogen, phosphorus and silicate; and using linked hydrodynamic
and biological models to investigate changes in nutrient cycling
and phytoplankton productivity in response to riverine freshwater
and nutrient inflows.
Coastal
Wetland Restoration: The Development of Functional Criteria to
Predict the Sustainability of Restored Wetlands
Mendelssohn, I., Louisiana State University,
Wetland Biogeochemistry
Project objectives
are to: determine the degree of sediment enrichment required to
achieve wetland sustainability based on the capacity to maintain
marsh elevation in the face of relative sea level rise (eustasy
plus isostasy); identify the mechanisms by which sediment subsidies
promote wetland sustainability; quantify the beneficial effects
of sediment amendments on ecosystem health via resilience assessments
and evaluation of the relationship between ecosystem health and
sustainability; and compare structural and functional properties
in restored and natural wetlands to establish whether marshes
restored by sediment-slurry enrichment are functionally equivalent
to reference marshes.
Development
of Seed-Based Spartina alterniflora (Smooth Cordgrass)
Propagation Technology for Coastal Wetlands Restoration and Remediation
Utomo, H., Rice Research Station, Louisiana
State University AgCenter
Coastal erosion
and wetland deterioration are serious problems affecting most
coastal regions of the United States, and nowhere is the problem
greater than in Louisiana. The technology for large-scale marsh
creation and marsh enhancement is advancing, with significant
growth in both the number of projects implemented and the acreage
of marsh restored annually. Revegetation following marsh surface
creation and enhancement is a critically important element in
achieving marsh sustainability and functionality in a timely manner.
Inaccessibility of many interior marsh restoration sites and the
high per-unit cost associated with colonial plantings will continue
to limit the use of plant materials as an element of coastal restoration.
Restored and enhanced sites left unplanted will colonize naturally
in a slow and uncertain recovery, often leaving areas bare and
unprotected for extended periods. Consequently, there is a need
to develop plant science technology for rapid and successful vegetative
restoration following large-scale marsh restoration projects.
A set of 13 fertile, superior and genetically diverse S. alterniflora
lines has been developed. These lines will be used to produce
seed of blend cultivars for use in coastal marsh restoration.
This proposed research will focus on developing seed-based restoration
technology and delivery systems that will advance the commercial
production of S. alterniflora seed and large-scale planting
by growers and conservation practitioners.
