Anderson, A. C., Tulane University School of Public Health and Tropical
Medicine, New Orleans, La., RECREATIONAL IMPACT OF FECAL LOADING ON LAKE
PONTCHARTRAIN BASIN STREAMS.
There have been several epidemiological studies addressing the health
implications of exposure to pathogens in recreational waters. These data,
including the study done at Lake Pontchartrain, are reviewed. Based on
these studies, EPA recommended new bacteriological criteria for
recreational water quality: 126 E. coli / 100 ml. fresh water or 33
enterococci / 100 ml. fresh water. Levels of these indicators and
sources of contamination are discussed using the Tangipahoa River as
a model for fecal loading of Pontchartrain Basin streams. The impact
of fecal contamination on other basin streams is also discussed. The
status of adoption of the new criteria organisms as bacteriological
standards for recreational water is reviewed. The steps being taken to
improve recreational water quality in the Pontchartrain Basin are
outlined.
Binet, G., St. Charles Parish, Hahnville, LA, and
Ensminger, A. B., Wetlands and Wildlife Management Co., Inc.,
Belle Chasse, LA, HABITAT DEGRADATION OF THE LABRANCHE WETLANDS AND AN
APPROACH TO ITS RESTORATION.
Considered the most productive wetlands within the Lake Pontchartrain
Basin, the LaBranche Wetlands south of Lake Pontchartrain consists of
over 14,000 acres of brackish to fresh marsh and forested swamp. Before
natural and man-made processes produced massive degradation and habitat
changes of the LaBranche Wetlands, the entire area was a freshwater
swamp and marsh complex. Between 1970 and 1980, one-fourth of the
LaBranche Wetlands habitat was lost due to saltwater intrusion, natural
subsidence, channelization, and shoreline erosion. Major contributing
factors to LaBranche's decline has been the dredging of access channels
for the construction of I-10, the construction of the Mississippi River
Gulf Outlet that periodically brings saltwater into Lake Pontchartrain
from the Gulf of Mexico, shoreline retreat of over 15' per year due to
Lake Pontchartrain wave action, and of course natural sediment depletion
and marsh subsidence.
In 1984, a comprehensive marsh management plan was developed for the
12,460 acres of LaBranche Wetlands owned and managed by the St. Charles
Land Syndicate. The area under management is generally bounded by Lake
Pontchartrain, the Jefferson/St. Charles Parish line, US Highway 61, and
Bayou LaBranche. In February 1987, the Louisiana Department of Natural
Resources/Coastal Management Division issued a coastal use permit for
the plan, and a Section 404 Permit was received from the US Army Corps
of Engineers in May 1988. Since that time, the LaBranche area north of
the Illinois Central Railroad (just south of I-10) has been passively
managed as a brackish to intermediate marsh, while the wetlands south
of the Illinois Central Railroad have been actively managed as a fresh
marsh and swamp complex. Structural modifications that plug or regulate
water flow through man-made canals has greatly improved LaBranche's
habitat for both fisheries and waterfowl production, has halted
saltwater intrusion in the area, and has increased the land to water
ratio within the entire complex. Steps have also been taken to
diversify marsh plants by implementing an annual re-vegetation program
aimed at introducing non-native and more salt tolerant plant species to
the area.
The LaBranche Wetlands is an excellent example of an environmental
public/private partnership. Over $2 million worth of marsh management
techniques have been implemented in LaBranche since the inception of the
plan, utilizing funds in the form of grants, mitigation, donations, and
landowner and Parish participation. The landowner and the Parish
realizes the major habitat role LaBranche plays to the Lake Pontchartrain
Basin, and has assumed an active role in preserving and enhancing its
valuable habitat.
Boebel, R. W., Consultant, New Orleans, LA., and Crawford, Frank C.,
Crawford & Associates, Inc., New Orleans, LA., THE LAKE BORGNE AND LAKE
PONTCHARTRAIN COMMERCIAL SEAFOOD PRODUCTION FROM 1970 TO 1989, VOLUMES
AND VARIATIONS.
Landings data compiled by the National Marine Fisheries Service, U.S.
Department of Commerce, show that the volume of seafood harvested and
sold commercially from lake Borgne and Lake Pontchartrain significantly
increased in the Twenty (20) year span, 1970-1989. The year 1989 is the
last year that this federal agency recorded fishery data from theses two
(2) state lakes.
Six (6) types of seafood (three (3) fish and three (3) shellfish),
comprising more than 99% of the total harvest, show an increase in total
poundage and total exvessel value from 2,075,100 pounds and $492,777 for
year 1970 to 8,946,150 pounds, and $6,103,237 for year 1989. The
species included are Drum (black) sea trout (spotted, white), sheepshead
(Atlantic), blue crab (hard, soft, peeler), shrimp (brown,white),and
oyster. All species increased over the period studied except oyster.
black drum, sheepshead, and blue crab showed the most dramatic
expansions of catch.
Substantial volume variations are present for some species within this
time span. Causal factors may include economic changes, shifting
demographies, and regulatory forces. The introduction of Mississippi
River freshwater and silt into these brackish water lakes probably
caused some fluctuations. Other physical changes in the environment
were occurring. Nevertheless, in 1989 Lake Borgne and Lake
Pontchartrain were not hostile to these members of the biota. Marine
life was alive, well, and harvested in large volumes by the commercial
fishing industry.
Brown, Murray L., Minerals management Service, New Orleans LA., A PUBLIC
DOMAIN SOFTWARE PROGRAM FOR CHARTING ENVIRONMENTAL ATTRIBUTES IN LAKE
PONTCHARTRAIN BASIN.
Although a number of excellent proprietary geographic information
systems (GIS) are in use by environmental resource agencies/groups in
southeastern Louisiana, there remains a need for an easy-to-use, well
documented, public-domain software program that allows general users to
prepare and share basic charts of environmental attributes using simple
ASCII files. The SEAPLOT software program, originally written for use
by oceanographers around the globe, has been expanded to include the
Lake Pontchartrain Basin on its regional selection menu. Although the
available coastline file is still rather crude, instructions are
provided to allow the user to import higher resolution files, if locally
available.
SEAPLOT is a menu-driven, interactive code written in GWBASIC (available
on most DOS personal computers). Using a specific data format described
in the available manual, the user can create, plot, and combine files
that depict locational information. To a lesser degree, certain
oceanographic parameters can be represented graphically, because the
program is provided as source code, the user can easily extend this
aspect of SEAPLOT to include water quality parameters. Locational
information that can be plotted includes boundaries, points, polygons,
as well as associated labels and titles. SEAPLOT is being used in
oceanographic research to plot ocean station locations, the tracks of
drifting buoys, water current and wind vectors, survey areas, stranded
marine mammal sites, oil spill dimensions, instrument sites, shipwreck
locations, and satellite analyses of ocean fronts. A utility routine in
SEAPLOT allows the user to add information to existing files using an
on-screen cursor. There is also a routine to sort data files according
to recommended file-naming conventions.
SEAPLOT Version 1.3 (which includes Lake Pontchartrain), with the draft
manual and a sampler of different data files, can be obtained by sending
one high-density, formatted, 5 1/4 inch floppy diskette to the author at
1201 Elmwood Park Boulevard, New Orleans, Louisiana 70123-2394, U.S.A.
Burns, J. W., Urban Waste Management and Research Center (UWMRC), M. A.
Poirrier, Biological Sciences \ UWMRC and K. Preston, Geography \ UWMRC,
University of New Orleans, New Orleans, LA, THE OCCURRENCE OF
POTAMOGETON PERFOLIATUS L. (CLASPING PONDWEED), A RARE SUBMERGED AQUATIC
VASCULAR PLANT IN LAKE PONTCHARTRAIN.
Submersed plants of both freshwater and marine origin comprise
important communities within estuaries, but their ecology in estuarine
habitats is poorly understood. Potamogeton perfoliatus L. (Clasping
Pondweed) is a submersed aquatic vascular plant which is listed as a
sensitive species in the coastal zone of Louisiana and is considered
extremely rare. Louisiana collections of P. perfoliatus are limited and
restricted to Lake Pontchartrain and its surrounding marshes.
Potamogeton perfoliatus was first recorded for Lake Pontchartrain
by Riddell in 1838 near the Tchefuncta River Lighthouse. Clair A. Brown
also collected a specimen from the beach at Mandeville in 1945.
Although Suttkus, Darnell and Darnell; Perret et al.; Chabreck; Turner,
Darnell and Bond conducted studies which noted the submerged vegetation
of Lake Pontchartrain in 1953-1954, 1971, 1972 and 1980 respectively,
P. perfoliatus was not reported in the lake for the following 28 years.
Montz reported P. perfoliatus to be abundant both before and after the
1973 opening of the Bonne Carré Spillway, at Pointe aux Herbes in the
southeastern sector of the lake. A 1978 icthyological survey by
Thompson and Verret, which noted submerged aquatic vegetation at
specific stations located around the perimeter of Lake Pontchartrain,
did not list P. perfoliatus as a species encountered. During the summer
of 1985, a survey of aquatic vegetation in the lake by Mayer did not
find P. perfoliatus. Efforts to relocate P. perfoliatus in 1988 by
Lester were unsuccessful during an ecological inventory of the sensitive
plants and animals for the coastal zone of Louisiana. Brantley and
Platt recorded a 7 m x 17 m submerged bed of P. perfoliatus 1500 m west
of Bayou Lacombe in June 1990. Additional smaller beds, which yielded
fruiting specimens, were located in the same area in August 1990.
Recent surveys beginning August 1991 to the present have located
submerged beds of P. perfoliatus on both the north and south shores of
Lake Pontchartrain. South shore beds have been located at Pointe aux
Herbes (39 m x 26 m) and at the confluence of Irish Bayou with Lake
Pontchartrain on the west side of the Pointe aux Herbes peninsula (50 m
x 50 m; 15 m x 12 m; 20 m x 15 m). North shore beds were located
between Goose Point and the confluence of Bayou Lacombe with Lake
Pontchartrain (15 m x 20 m; 10 m x 15 m), approximately 4.0 km east of
Bayou Lacombe near Point Platte (150 m x 120 m) and off the swimming
beach at Big Point (several individuals). Attempts to relocate P.
perfoliatus at Big Point during December 1991 were unsuccessful.
Submersed beds of P. perfoliatus reported by Brantley and Platt were
also relocated near Bayou Lacombe.
Factors affecting the distribution of P. perfoliatus in Lake
Pontchartrain are not known. Some areas have been repopulated after an
absence of 18 years, and growth is occurring in previously unreported
sectors of the lake. Its status in Lake Pontchartrain is currently
being monitored and examined for factors which affect its distribution.
Calix, A. G.; Seeger, E.; Velado, L.; Rucker, J.; TGS Technology, Inc.,
U.S. Fish and Wildlife Service, National Wetlands Research Center,
Slidell, La, and Handley, L. R., U.S. Fish and Wildlife Service,
National Wetlands Research Center, Slidell, La, SHORELINE CHANGES OF
LAKE PONTCHARTRAIN 1955-1990.
Lake Pontchartrain plays an important role in the wetland ecosystems of
Louisiana. Over the past few decades the lake has been directly
affected by the urban development of New Orleans and surrounding areas.
Shell dredging, saltwater intrusion, shoreline development, and
pollution are some of the factors contributing to the lake's problems.
Recently, efforts have been made to restore the lake to an ecologically
sound and economically viable habitat for Louisiana. The purpose of
this study is to cartographically demonstrate the changes in the
shoreline of Lake Pontchartrain using historical maps and recent aerial
photography.
Conatser, W. E., New Orleans, La., PETROLEUM INDUSTRY ACTIVITY IN THE
LAKE PONTCHARTRAIN BASIN.
The petroleum industry has had a commercially successful and
environmentally compatible history in the waters of the Lake
Pontchartrain Basin for over 53 years. Gulf Oil Co. completed the first
well in Lake Pontchartrain on July 17, 1938. Since that time 266 wells
have been drilled in the waters of Lake Maurepas, Lake Pontchartrain,
Lake St. Catherine and Lake Borgne. These wells have penetrated more
than 2,762,000' of strata for an average depth of 10,383' per well. The
deepest well to date was drilled to a depth of 25,600' by Placid Oil Co.
on their State Lease 5407 in Lake Borgne. The deepest well to date in
Lake Pontchartrain is the Union Of California - State Lease 6753 #2
which reached a total depth of 22,904'.
The petroleum industry has completed 86 (32.3%) of the wells drilled as
commercial or possibly commercial. The first commercial well was
drilled by Atlantic Oil and Refining at Big Point Field near the north
shore of Lake Pontchartrain in September of 1946. Since that first
completion the wells in the waters of the Lake Pontchartrain Basin have
produced 10,017,352 barrels liquid hydrocarbons and 116,204,782 MCF
natural gas.
It is not possible to predict the future production of oil and gas from
the lakes of the study area but the potential is considered significant.
Currently oil and gas is produced from strata ranging in age from Middle
Miocene through the Upper Cretaceous. Trap types vary from elongate
anticlines, to fault closures, to stratigraphic traps. Prospective
areas remain to be drilled in the study area. New exploration
techniques and recovery advancements could present possibilities for
future petroleum production far exceeding those already produced.
Condrey, Richard, Coastal Fisheries Institute and Department of
Oceanography and Coastal Sciences, Louisiana State University, Baton
Rouge, La, HISTORICAL ECOLOGY OF LAKE PONTCHARTRAIN - BORGNE BASIN:
1699-1950.
Once Iberville passed the buffalo plains and cypress swamps which were
to become New Orleans (because the area had a fine path which led to
Bayou St. John and then Lake Pontchartrain), he began looking for the
right fork of the Mississippi. Failing to find it (since he was on it
and failed to recognize Bayou Lafourche as its left fork), he took a
small bayou chocked with huge log jams (Bayou Iberville, now Bayou
Manchac) through Lake Pontchartrain-Borgne.
Come on a voyage of discovery as we relook at this system through the
writings and illustrations of the early explorers and visitors. From
Iberville and Collot, through Audubon, and Lafcadio Hearn and Rebecca
Harding Davis, watch the massive ecological changes brought by European
settlement. Ponder what the system was as you consider what it might
become.
Caraher, M. F., W. M. Dahl, and D. H. Easley, University of New Orleans,
New Orleans, LA, COMPARISON OF SINGLE-WELL AND TWO-WELL TRACER TESTS FOR
ACQUIRING VELOCITY AND EFFECTIVE POROSITY ESTIMATES IN THE PINE ISLAND
AQUIFER, NEW ORLEANS, LA.
The Pine Island aquifer is a barrier spit sequence located primarily in
the northern portion of Orleans parish, Louisiana. this aquifer is
approximately 25 feet thick in the study area located on the western
edge of the University of New Orleans Lakefront campus. Estimated
transmissivities are approximately 3700 gal/day ft and storativity
estimates are approximately 0.00036. Average linear velocities are
approximately 0.2 feet per day. The aquifer consists of a fine-grained
sand with shell fragments underlain by finer grained bay sediments and
overlain by silt and clay fill pumped from Lake Pontchartrain. This
aquifer provides an ideal site for comparison of tracer tests.
A small well field, which consists of four fully-penetrating wells, have
been installed into the Pine Island Aquifer. Both single-and dual-well
tracer tests may be used to determine estimates of average linear
velocity and effective porosity. These tests may be complicated by
minimal gradient that results in low ground-water velocities, such as
occur in the Pine Island Aquifer. Low velocities require extended
breakthrough monitoring, which may be expensive if shorter well spacing
is impractical.
The intent of this project is to provide an inexpensive, simple, and
relatively rapid method of estimating velocity and effective porosity in
aquifers commonly found south of Lake Pontchartrain. Our study utilizes
the single-well drift and pump-back technique described in Hall et al.
91991) and standard dual-wellpumping tracer tests. The single-well
drift and pump-back method allows the estimation of both average linear
velocity and effective porosity simultaneously. The dual-well test will
be performed as a comparison with the single-well test, using the same
portion of the aquifer. The results are then evaluated to determine
their reliability and overall utility.
Davis, D. W., Louisiana Geological Survey, P.O. Box G - University
Station, Baton Rouge, Louisiana 70893, NEW ORLEANS---NORTH AMERICA'S
PREMIER BELOW SEA LEVEL CITY.
In the current popular and scientific literature one reads with repeated
frequency articles related to the greenhouse effect on sea level rise.
As the world turns up its global thermostat, melting the polar ice caps
and enlarging the world's seas through thermal expansion, coastal cities
will be at risk. With nearly two-thirds of the planet's population and
more than 40 of its largest metropolitan centers within the coastal
lowlands, even a small upward movement in the earth's seas is
significant. A change in temperature of as much as 4o C has been
predicted by 2030, that could elevate sea level enough to flood New
Orleans and other coastal municipalities.
From its inception, New Orleans was isolated from the mainland by
cypress/tupelo swamps, marshes, and Lake Pontchartrain. It was an
"island city" delineated by water courses. When surveyed in 1720 every
block was defined by shallow ditches. From its beginning these small
channels established New Orleans' dependence on a drainage network.
Levee construction began as early as 1718. By 1720 all inhabitants were
instructed to enclose their land in "palisades" or forfeit their
property. Ten years later an embankment 1.6 km long protected the
"Vieux Carre." Levees, therefore, are an old and integral part of the
urban landscape. New Orleans is part of an environmental setting that
requires an extensive levee and pump system to manage the region's
excess water.
The "Vieux Carre" is the older section of the "Crescent City" and is
built on abandoned or modern natural levees. At 4.5 m above sea level,
these features are the region's high ground. They furnished the
earliest inhabitants with a relatively dry, firm foundation for
residential and commercial construction. Draining the surrounding
wetland was a major undertaking. When the water was removed the soils
shrank and settled and eventually subsided below sea level. Even so,
relatively rapid urbanization required additional space. The only
property available were the swamps and marshes that framed the initial
natural levee site. What was delineated as "uninhabitable wasteland"
was slowly reclaimed as the region's incorporated limits increased.
Much of the New Orleans' metropolitan complex has subsided to the point
where in order to drain properly pumps siphon excess rainfall up into
Lake Pontchartrain. Human-induced negative land surfaces are producing,
in many instances, below sea-level citizens. Regional governments have
learned, nevertheless, to live with this and other environmental
dilemmas. Canals, pumps, and large-diameter drainage pipes assist in
keeping the neighborhoods relatively dry. With much of the urbanized
area less than 3 m above mean sea level, the margin of safety is
exceedingly small. This is particularly true for those sections of the
levee-protected metropolitan region 2 m to 4 m below sea level. In as
much as arable land has always been in short supply, the only practical
and realistic solution was to reclaim the "uninhabitable" swamps and
marshes. Soils associated with these aquatic habitats are subaqueous in
origin and high in organic detritus. When air dried, these histosols
lose nearly 85% of their mass. The end result is the surface subsides,
because of the loss of volume within the soil column.
The product of reclaiming these marginal tracts is that the New Orleans'
metropolitan region is sinking. With a projected rise in sea level of
1.2 mm/yr, coupled with a constant battle with subsidence, the New
Orleans metroplex faces a challenging future. In addition, the
metropolitan area is at risk from hurricanes. Under the right
conditions, a tropical depression moving across Lake Pontchartrain's
southeastern quadrant would move considerable water over the lakefront
levees into the below-sea-level bowl that distinguishes parts of
Jefferson and Orleans parishes. For more than two and a half centuries
the "Crescent City" and its satellite communities have been at odds with
the elements. Despite these issues, the region has developed, prospered,
and flourished within this inhospitable environment, but the future must
be considered carefully.
DeLaune, R.D and Pardue, J.H., Wetland Biogeochemistry Institute,
Louisiana State University, Baton Rouge, La. DISTRIBUTION OF HEAVY
METALS IN BAYOU TREPAGNIER BOTTOM SEDIMENT.
The depositional pattern of metals was determined in bottom sediment of
Bayou Trepagnier (located in the La Branche Wetland bordering Lake
Pontchartrain). The majority of flow into the Bayou is from an
industrial outfall. Eight cores were taken from Bayou Trepagnier and one
core from Mississippi Bayou ( a control site ) along a transect
extending to Lake Pontchartrain. Results indicated that Bayou Trepagnier
sediment was contaminated with chromium, lead, and zinc. Chromium levels
of over 5,000 mg/kg of sediment were measured in sediment profiles. Lead
concentrations on the order of several thousand mg/kg were observed in
the lower sediment profile taken near the industrial discharge sites.
Zinc concentrations of greater then 1,000 mg/kg of sediment were
recorded. Concentrations of metal increased with depth in the profile.
Metal concentrations were normalized to Al in the sediments and compared
to uncontaminated sites in Louisiana. Bayou Trepagnier sediments were
shown to be highly enriched with respect to Cr and Pb when compared with
other areas of the state. Sedimentation in recent years (determined from
137Cs dating) was burying or removing metals from the surface
environment where bioavailability is greatest.
Delaune, R.D. and Lindau, C.W.,Wetland Biogeochemistry Institute,
Louisiana State University, Baton Rouge, La, STABLE NITROGEN ISOTOPES
STUDIES FINGERPRINT SURFACE WATER INORGANIC NITROGEN SOURCES ENTERING
THE PONTCHARTRAIN BASIN.
Estuaries such as Lake Pontchartrain are generally nitrogen limiting.
Nitrogen entering the system can influence water quality of the lake. A
recent study investigated the use of natural abundance variations in
15N/14N ratios for identification and tracing surface water inorganic N
sources entering the Pontchartrain Basin.Surface water samples were
collected from selected streams with distance from a point source in the
northern Basin and analyzed for NH4+-N, NO3--N and associated 15N/14N
(d15N%) concentrations. Ammonium-N from domestic sewage sources entering
the Basin was found to have distinct d15N ranges. Domestic sewage
discharge was traced for about 30 km downstream from discharge point
using 15N/14N ratios. At the sewage point source NH4+-d15N values
averaged +43% and increased linearly to +162% with distance from the
discharge. Surface water NO3--d15N values generally ranged from +1 to
+99% and no significant association was observed between d15N values
with distance from the domestic sewage point sources. The discrete
NH4+-d15N signatures of domestic sewage compared to downstream surface
water. NH4+-d15N values demonstrated that N isotopic ratios can be used
as tracers for identifying the sources of nitrogen entering the
Pontchartrain Basin. Such sources include the nitrogen in dairy manure
entering the Tangipahoa river and septic and sewage being introduced
into the Amite and Tickfaw rivers. Expanded studies are currently being
initiated to further quantify nitrogen sources entering the basin.
Demans, Charles R. and Garrison, Charles R., Water Quality Monitoring
Activities of the U.S. Geological Survey in the Lake Pontchartrain and
Lake Maurepas Basins
The Louisiana District of the U.S. Geological Survey Water Resource
Division has been involved in monitoring the water quality of surface-
and ground-water resources of the Lake Pontchartrain and Lake Maurepas
basins since 1927. Surface-water samples and volumetric flow rate
discharge measurements have been made at 210 sites in these two basins.
Surface water quality samples have been collected at 102 sites,
accounting for 2,187 water samples to date. Bed samples have been
collected at 28 of the above sites, accounting for 30 samples. Water
and bottom material have been analyzed for suspended sediment,
nutrients, bacteria, major ions, trace metals, and pesticides.
Currently, there are three active water-quality sites within the two
basins. These data were collected as part of cooperative programs with
the Department of Transportation and Development, the U.S. Army Corp of
Engineers, and the U.S. Geological survey NASQAN program.
Ground water has been sampled at approximately 1,160 sites within the
basins, accounting for 3,823 samples. Ground water has been analyzed
for primarily major ions and selective nutrients, although synthetic
organic compounds, trace metals, and bacteria have been run at selective
sties. Ground-water data have been collected as part of cooperative
programs with the Department of Transportation and Development,
Jefferson Parish Department of Water, and St. John the Baptist Parish
Department of Water.
The U.S. Geological Survey also has completed several interpretive
studies within the Lake Pontchartrain and Lake Maurepas basins. Studies
completed on ongoing include:
- Movement of bacteria in shallow ground water,
- Assessment of trace metals in coastal streams (Pear River,
Tickfaw River),
- Hydrology of Fritchie marsh, coastal Louisiana,
- Ground-water resources of southern Tangipahoa Parish, and
- Several other general water-quality studies.
Devall, Margaret S. and Parresol, Bernard R. Souther Forest Experiment
Station, 701 Loyola Avenue, Rm. T-10210, New Orleans, LA 70113.
ASSESSING THE EFFECTIVENESS OF SEVERAL PROTECTIVE MEASURES AGAINST
HERBIVORY OF CYPRESS TAXODIUM DISTICHUM SEEDLINGS.
Second growth cypress remains an important source of lumber and is
important for its ecological and aesthetic role, and for wetland
preservation. Louisiana contains a larger inventory of baldcypress than
any other state, but subsidence and hydrological modification are
reducing natural regeneration. Planting programs have been instituted,
but nutria and swamp rabbits have become serious deterrents to the
success of cypress plantings in Louisiana. This study examines the
effect of treatments offering possible protection against herbivory by
nutria and swamp rabbits, and assesses seedling growth (height and root
collar diameter) with various treatments. Treatments include
application of tanglefoot, a sticky resin; application of ropel, a
rodent repellent; and the use of plastic tree guards. Study sites are a
marsh that was formerly a cypress swamp on the U.S. Fish and Wildlife
Service's Bayou Sauvage Wildlife Refuge and a marsh on Southeast
Louisiana University's Turtle Cove Research Station near Pass Manchac.
The Study is in its second year.
Dranguet, C. A., Southeastern Louisiana University, Hammond, LA., and
Heleniak, Roman J., Southeastern Louisiana University, Hammond, LA., MAN
IN THE BASIN: HABITATION AND FOREST EXPLOITATION IN THE PONTCHARTRAIN
BASIN.
Man's entrance into the Pontchartrain Basin has been marked by a
degradation of the cypress swamp that at one time surrounded Lake
Pontchartrain. The coming of the railroad to the western shore of the
Lake in 1854 opened the area to commercial exploitation. through war,
flood, and man's utilization of the Basin's resources, the gradual
shrinking of the forest was only inevitable.
The purchase of vast tracts of virgin cypress stands by commercial
lumber interests in the 1880's sealed the eventual fate of the forest.
A short one hundred years elapsed between the introduction of modern
transportation and logging techniques, the establishment of communities,
and the final destruction of the swamp habitat.
Duffy, K. C., Dept. Oceanography and Coastal Sciences, LSU, Baton Rouge,
LA., and Baltz, D. M., Coastal Fisheries Institute, LSU, Baton Rouge
LA., THE INFLUENCE OF THE INTRODUCED EURASIAN MILFOIL (MYRIOPHYLLUM
SPICATUM) AND NATIVE AQUATIC VEGETATION ON FISH NURSERY HABITAT IN LAKE
PONTCHARTRAIN.
Quantitative samples in monospecific stands of submerged aquatic
vegetation (SAV) and bare sands habitats have been collected on a
monthly basis from three stations in the northeastern area of the Lake
Pontchartrain estuary since July, 1991. the samples of the community
associated with the SAV beds are being collected with a Wegener ring
(1.2 m ), in a microhabitat approach to describe the population response
of fish, invertebrate, and SAV species to environmental variables.
these data are being used to evaluate the impact of an introduced SAV
species on the community structure of coastal fishes and invertebrates
in Lake Pontchartrain and its adjacent waters. Historically, the
dominant native SAV species were Vallisneria americana and Ruppia
maritima; however, Myriophyllum spicatum became established and abundant
in the 1970's. In this study, we have seen dynamic changes in the SAV
species composition that may be seasonal or directional and related to
recent changes in lake water quality. Presently, 9 fish and 9
invertebrate species have been identified. From the preliminary
samples, the mean numbers per sample (range) for fishes and
invertebrates, respectively, are 12.5 (0-39), and 235.7 (11-508).
Species of commercial and recreational interest include juvenile spotted
seatrout and blue crab, and post-larval penaeid shrimp.
Earl, C., Hicks, B., and Hull, F., U.S. Army Corps of Engineers, New
Orleans, LA, JEFFERSON AND ORLEANS PARISHES, LOUISIANA, URBAN FLOOD
CONTROL AND WATER QUALITY MANAGEMENT STUDY.
The new Orleans District Corps of Engineers is currently conducting a
reconnaissance study entitled, JEFFERSON AND ORLEANS PARISHES,
LOUISIANA, URBAN FLOOD CONTROL AND WATER QUALITY MANAGEMENT.
the purpose of the study is to consider measures to alleviate rainfall
flooding in the parishes and to improve the water quality of stormwater
discharges into Lake Pontchartrain, Lake Borgne, and the Barataria
Estuary.
Our goal for the water quality management plans under consideration is
to reestablish the designated use of the receiving waterbody, such as
making it swimmable and fishable.
During the reconnaissance phase we rely heavily on existing data. We
determined the impacts of stormwater runoff using a preliminary
screening procedure recommended by EPA. Based on research of the best
available technology, we will estimate the cost and effectiveness of the
various water quality management plans.
The Reconnaissance Report will discuss a wide range of alternatives,
such as source controls, in-line treatment, and end-of-pipe treatment.
Ellis, L. E., Biological Sciences / Urban Waste Management and Research
Center (UWMRC), UNO; Francis, J. C., Biological Sciences / UWMRC, UNO;
and Tracy D. K., Biological Sciences, UNO. DETERMINATION OF FECAL AND
TOTAL COLIFORM LEVELS IN LAKE PONTCHARTRAIN BY POLYMERASE CHAIN REACTION
(PCR).
Fecal coliform and total coliform levels were monitored in Lake
Pontchartrain over a several month period using oligonucleotide primers
for detection of the lacZ and uid DNA sequences by PCR. Good
correlation was realized between PCR detection and standard method
procedures. Refrigerated storage of water samples prior to PCR
detection was evaluated. Bacteria were detectable for 10 days but
showed significant declines after 48 hours. High fecal and total
coliform levels in Lake Pontchartrain appear to be associated with high
turbidity of the water.
Emmer, R. E., College of Urbanand Public Affairs, University of New
Orleans, New Orleans, LA. SHRINKAGE OF THE PONTCHARTRAIN BASIN, THE
NEED FOR A COOPERATIVE REGIONAL APPROACH.
The Pontchartrain basin in shrinking in our perception of its size, the
remoteness of the headwaters, the vastness of its waterbodies, the
supply of natural resources, and the rapidity of population growth and
how soon their presence is felt by neighbors. Tradition segments the
basin into four regions: metropolitan New Orleans or the south shore;
the river parishes from St. Charles to Iberville Parish; the north shore
of St. Tammany, Washington, and Tangipahoa Parishes; and the distant
headwaters, the Amite River watershed including East Baton Rouge,
Livingston, East Feliciana, and St. Helena parishes. these regions have
historically acted independently for several reasons. Culturally, they
were distinct, i.e., Anglo-Saxon vs. French vs. The City. Second, the
regions were separated by distance. Trips between regions as late as the
1940s were major excursions because of the absence of all-weather roads
and bridges over major waterbodies such as the Rigolets, Pass Manchac,
and the many rivers. Third, the economic foundation of each region was
different. Finally, popular beliefs and attitudes ranged from Laisse
lse bons ton rouler to strict biblical followings.
Communities were scattered clusters of homes and businesses along the
Mississippi River; isolated groupings of stores and residences at
cross-roads or spaced along the bayous, railroads, and highways.
Because these enclaves were small they were insulated from their
neighbors and, thus, were little affected by or had little effect on the
nearest villages, much less Lakes Maurepas or Pontchartrain. The
Pontchartrain minimal if any significant adverse impacts extending
beyond the boundaries of the community. Post World War II growth,
improved highways, the automobile, and industrial development have
changed the basin from overall rural to an emerging suburban/urban
system. Time and space are compressed and with an increasing population
problems are magnified. The basin has become one community whether it
wants to be or not. I turn, our common problems must be approached in
new ways.
The Pontchartrain basin as one community faces many institutional and
environmental problems. Federal, state, and local laws and
jurisdictions overlap and, in many instances, conflict in mission and
authority. In addition, the private landowner is concerned with his/her
right to use property in a way that benefits them. Water quality,
wetland loss, harvesting of renewable resources, and extraction of
minerals are issues that confront decision makers in the basin and can
no longer be ignored. Planning offers the vehicle for addressing these
issues in a timely and systematic manner. Former Governor of California
Edmund G. Brown said, "planning is thinking ahead intelligently ..."
and an idea that has received wide acceptance. In fact, it is
methodically avoided by many parishes and municipalities. Such as
negative attitude requires modification if the institutional and
environmental problems of the basin are to be solved in a timely
fashion. The Lake Pontchartrain Basin Foundation through a grant from
the Environmental Protection Agency is undertaking a basin planning
process that will confront many of the most difficult institutional and
environmental problems in the basin. What evolves will be a formal
regional cooperative mechanism for formulating positive actions that
result in a healthier and safer place to live for the people in the
basin.
Farabee, M.V., and R.C. Cashner, Department of Biological Sciences,
University of New Orleans, New Orleans, LA, DISTRIBUTION OF FISHES AND
COMMUNITY STABILITY IN BAYOU LACOMBE.
Bayou Lacombe is a relatively small drainage system tributary to the
northeastern section of Lake Pontchartrain. Based on records from fish
collections made since 1951, a total of 77 resident and migratory
species have been documented for the system. Bayou Lacombe has been the
focus of four major ichthyofaunal surveys. The most extensive study was
done by Sobczak, in which 10 stations were sampled monthly from August,
1973 to August, 1975, and the most recent survey included monthly
samples at five sites from November, 1988 to October, 1989. Numerical
dominants in the upper reaches of Bayou Lacombe include grass pickerel,
chubsuckers, black bullhead, bayou topminnow, mosquitofish, dollar
sunfish, and warmouth. The middle of the river has greater numbers of
cyprinids, blackspotted topminnow, brook silverside, and longear
sunfish. The longitudinal pattern of distribution of fishes in Bayou
Lacombe is characterized by a rather abrupt change in the fauna between
upper, middle, and lower reaches, rather than addition of species.
Morisita's Index (Im) and Percent Similarity Index (PSI) indicate that
the greatest dissimilarities between fish assemblages occur between the
lowermost stations and those above tidal influence. Stations near the
mouth of Bayou Lacombe are characterized by euryhaline forms, such as
bay anchovy, Gulf menhaden, inland silverside, sciaenids, and gobies.
Community similarities were calculated for five common stations between
the 1973-75 and 1988-89 surveys. Relatively low values for Im and PSI
may indicate less stability and persistence of fish communities over
time than reported for midwestern streams. The most abundant species,
the blacktail shiner, collected during the 1973-75 study was not
represented in any of the 60 collections made during the 1988-89 survey.
Francis, J. C., Biological Sciences / Urban Waste Management and
Research Center (UWMRC), UNO; Wijesundera, V., UWMRC, UNO; Barbe, D. E.,
Civil Engineering / UWMRC, UNO; Mulino, M. M., Steimle & Assoc., Inc.,
Metairie, La.; and Poirrier, M. A., Biological Sciences / UWMRC, UNO.
HISTORIC CHANGES IN SECCHI DISK TRANSPARENCY IN LAKE PONTCHARTRAIN.
A major environmental concern about Lake Pontchartrain is an
assumed long-term decrease in water clarity. Available data on Secchi
disk transparency in Lake Pontchartrain from 1953 through 1990 were
examined to determine if changes in water clarity had occurred. Linear
regression analysis of Secchi disk transparency versus time indicated a
statistically significant (5% level) decrease in transparency with time.
The relationship between Secchi disk transparency and two
environmental factors, salinity and wind speed, were studied using
regression analysis. The analysis revealed a statistically
significant, positive relationship between water clarity and salinity,
and a statistically significant, negative relationship between water
clarity and wind speed. Further analysis indicated that neither
average annual salinity nor average annual wind speed had realized a
statistically significant change during the period from 1953 through 1990.
Secchi disk transparency data were adjusted for the effects of
salinity, wind speed, and both salinity and wind speed. The base for
adjustment in each case was the long-term average of the variable for
which adjustment was being made. Regression of Secchi disk
transparency versus time, with adjustment for salinity, revealed a
statistically significant relationship, indicating that adjusting the
data for the effect of salinity had not removed the long-term decrease
in water clarity. However, regression of Secchi disk transparency
versus time, with adjustment for wind speed, indicated that there was no
longer a statistically significant relationship between Secchi disk
transparency and time. Adjusting the data for the effect of wind speed
had removed the long-term decrease in water clarity. Also, regression
of Secchi disk transparency versus time, with adjustment for both
salinity and wind speed, revealed no statistically significant
relationship, indicating that adjusting the data for the effects of
both salinity and wind speed had removed the long-term decrease in
water clarity.
Analysis of variance of monthly salinity data from 1953 through
1990 revealed a statistically significant monthly seasonality with the
highest values occurring in November and the lowest values occurring in
May. Similarly, analysis of variance of monthly wind speed data from
1953 through 1990 revealed a statistically significant monthly
seasonality with the highest values occurring in February and the
lowest values occurring in August. These seasonal effects are not
equally represented in the available data on Secchi disk transparency
in Lake Pontchartrain. When the seasonal bias is removed from the data
set, it no longer supports the conclusion of a statistically
significant change in Secchi disk transparency from 1953 to 1990.
Goyer, R.A., G. J. Lenhard, J. L. Chambers, LA Agricultural Experiment
Station, LSU, Baton Rouge, LA, and V. R. Van Sickle, U.S. Fish &
Wildlife Service, National Wetlands Research Center, Lafayette, LA,
HERBIVORY IN BALDCYPRESS: A THREAT TO THE PONCHARTRAIN BASIN
The future of the baldcypress is closely linked to its ability to
withstand environmental, biological and man-caused stresses. Currently,
all three of these categories of stress are impacting cypress in south
Louisiana and, particularly, threaten trees in and near the Ponchartrain
Basin. Studies underway by the authors are evaluating the impact of an
herbivore - the fruit tree leafroller (Lepidopter: Tortricidae) - on
baldcypress. Further evaluations are being conducted to ascertain the
interaction(s) of herbivory with flooding caused by man made and
environmental changes (e.g., global warming and associated changes in
hydrology). Studies to date have revealed continued expansion of fruit
tree leafroller populations into the periphery of the Ponchartrain
Basin. In areas having experienced repeated defoliation of cypress,
radial growth has shown marked reduction. Additionally, crown
deterioration, increased transparency and dieback have occurred along
with scattered tree mortality. The threat to baldcypress results from
herbivory coupled with changes in hydrology. Sapling and pole-sized
cypress exhibiting high live-crown ratios appear most heavily browsed.
Transect evaluations presently underway are aimed at evaluating severity
of herbivory in relation to seasonal flooding regimes. Rates of
refoliation on both mature and young saplings are compared to further
elucidate the ability of cypress to respond to herbivore and flooding
stresses.
Hardy, J. W., Southern Regional Climate Center, Department of Geography
& Anthropology, Louisiana State University, Baton Rouge, La, 70803,
FRESH WATER INPUT INTO LAKE PONTCHARTRAIN.
Fresh water input into Lake Pontchartrain will be determined for a wet
year and dry year. The amount of runoff generated by each drainage
basin of Lake Pontchartrain will also be examined. Fresh water input
into Lake Pontchartrain will be found in part from measured runoff at
gaging stations along Highway 190. The Thornthwaite water budget model
will be used to estimate the surplus water, hence runoff, for the part
of the Pontchartrain drainage basin below the gaging stations. Actual
evaporation and the change in soil moisture storage will be subtracted
from precipitation to give the surplus for the ungaged uplands. The
freshwater input into Lake Pontchartrain from the ungaged swamps,
marshes, and lakes will be found by subtracting potential evaporation
from precipitation.
Hastings, Robert W., Turtle Cove environmental Research Station,
Southeastern Louisiana University, Hammond, LA, SURFACE DRIFT MOVEMENT
OF LARVAL MARINE FISHES AND OTHER ORGANISMS THROUGH PASSES OF THE UPPER
LAKE PONTCHARTRAIN ESTUARY.
The fish fauna occurring in the oligohaline upper Lake Pontchartrain
estuary consists of about half freshwater species and half marine.
Freshwater species are present throughout the year whereas most marine
species are seasonal in their occurrence, leaving the upper estuary for
the winter. A major occurrence, leaving the upper estuary for the
winter. A major influx of such species occurs in the spring as larvae
and early juveniles. Surface plankton net sampling has been conducted
to monitor patterns of movement for several fish species, such as bay
anchovy (Anchoa mitchilli), gulf menhaden (Brevoortia patronus), gulf
pipefish (Syngnathus scovelli), naked goby (Gobiosoma bosci), and
tidewater silverside (Menidia beryllina), as well as several
invertebrates such as blue crab (Callinectes sapidus ). Samples have
revealed significant seasonal, diel, and spatial patterns of occurrence
for several species common in the estuary. Thus they may exercise
significant control over their movements, even though they are small and
appear to be poor swimmers. Although open waters of the upper estuary
are clearly used as nursery habitats for such species, their use of
enclosed marsh canals and bayous may be more limited. Studies are
continuing to address such movement (or lace of movement) of small
planktonic organisms into enclosed waters, and how diel variation in
activity patterns affects their patterns of occurrence in surface
plankton samples.
Keim, B.D., Southern Regional Climate Center, Department of Geography
and Anthropology, Louisiana State University, Baton Rouge, Louisiana
70803. STORM FREQUENCIES AND STORM RUNOFF INTO LAKE PONTCHARTRAIN.
The large number of recent heavy rainstorms in southeastern Louisiana
has raised concerns about changing frequencies and magnitudes of heavy
rainfall in the area. A changing heavy rainfall climatology over the
Lake Pontchartrain Basin may have noteworthy impacts. Most storm runoff
from New Orleans is discharged into the lake and is obviously important
to the lake's water quality. Furthermore, storm runoff from the rivers
draining the Florida Parishes transports agricultural wastes into the
lake and influences lake salinity levels. This paper examines the
historical storm events in metropolitan New Orleans and the Florida
Parishes from the nineteenth century to the present. The seasonality
and synoptic situations of storm rainfall will also be examined.
Lawler, G. C., Delgado Community College, New Orleans La., and Hartzog,
L., Army Corps of Engineers, New Orleans, LA., BASELINE POLLUTANT DATA
ON WATER COLUMN, SEDIMENT, AND BIVALVE TISSUE SAMPLES FROM THE INNER
HARBOR NAVIGATION CANAL, CHEF MENTEUR PASS, AND THE RIGOLETS.
As part of the environmental impact statement supporting the Army Corps
of Engineers' Hurricane Barrier Protection Plan, pollutants in the water
column, sediment, and bivalves of the Inner Harbor Navigation Canal (
IHNC), Chef Menteur Pass, and The Rigolets were investigated. This
investigation was carried out in tow phases. In phase I, methods were
developed, the three passes were screened for pollutants, and replicate
samples were analyzed to determine the number of samples required to
achieve reasonable analytical precision. Phase I culminated with the
production of a sampling protocol, which included various sampling
options and tables relating numbers of samples to analytical precision.
Phase II, which was designed to detect seasonal fluctuations of
pollutants, was aborted with the Hurricane Barrier Protection Plan was
abandoned. The first samples were collected for analysis in May of
1980. The data generated from these and subsequent analyses qualify as
baseline data for these location and matrices because the analyses were
carried out under rigorous conditions of quality assurance and the
analytical techniques employed were state-of-the-art. The major
analytical effort was directed toward detecting and quantifying EPA
designated priority pollutants. In addition, organic fractions were
routinely searched for compounds of probable anthropogenic origin.
Water samples were analyzed for asbestos, heavy metals, base-neutral and
acid extractable organics, organochlorie pesticides and polychlorinated
biphenyls, volatile organics, acrolein and acrylonitrile, total cyanides
and total recoverable phenolic. Sediment samples were analyzed for
heavy metals, total base-neutral extractable organics, individual
base-neutral extractable organics, organochlorine pesticides and
polychlorinated biphenyls, and volatile organics. Bivalve tissue
samples from oysters (Crassostrea virginica) and clams (Rangia cuneata)
were analyzed for heavy metals, total base-neutral extractable organics,
individual base-neutral extractable organics, organochlorine pesticides
and polychlorinated biphenyls, and voltile organics. The results of
these analyses were compiled in seven data reports submitted to the Army
Corps of Engineers in association with the "Nutrient and Toxic Substance
Chemistry of Chef Menteur Pass, The Rigolets, and Inner Harbor
Navigation Canal, Lake Pontchartrain, Louisiana" program. The results
of dissolved inorganic nutrient analyses conducted on the water samples
were included in the data reports.
Lopez, John A., Amoco Production Co., New Orleans La., POTENTIAL
SIGNIFICANCE OF ACTIVE FAULTS IN LAKE PONTCHARTRAIN.
Examination of conventional seismic data collected in Lake Pontchartrain
leads to the compelling conclusion that the eastward extension of the
Baton Rouge-Denham Springs faults system is within Lake Pontchartrain
and not as previously mapped on the northshore of the lake. The
Pleistocene/Holocene contact previously mapped as faults on the north
shore is probably a depositional contact. The faults within the lake
are presently active as is the Baton Rouge/Denham Springs fault system.
Evidence for recent movement on the faults within the lake is strongly
suggested by offset of the bridges which cross the lake. Offset varies
from 2 to 6.5 inches depending on the age of the bridge. Movement on
the fault is approximately 1 inch per decade (.25 cm / year). Less
detailed mapping suggests the fault system extends into Chandeleur
Sound. Thus the Baton Rouge-Denham Springs fault system is a regional
basement fault system extending 120 miles from Baton Rouge to Chandeleur
Sound. One of the probable effects of this fault system is to trigger
small earthquakes, such as the 1987 Irish Bayou earthquake. Other
historic earthquakes located 5 to 20 miles south of the fault trace may
have also been related to the fault system. Past activity suggests that
an earthquake hazard is minimal. Other consequences or significant
questions in relation to the active faults are:
1) The current high rate of movement on the faults is probably
higher than in the geologic past. So why does movement on the
faults appear to have accelerated in the Holocene?
2) The coincidence of the regional fault system within Lakes
Maurepas, Borgne, and Pontchartrain suggests a genetic
relationship. Do prior models for the formation of Lake
Pontchartrain need to re-evaluated?
3) At least two significant studies of ground water aquifers
in Lake Pontchartrain indicate that some of the faults do seal
some of the aquifers. Since the faults are a series of
discontinuous faults the hydraulic connection of fresh and saline
aquifers is complex and probably intimately related to
faulting in the lake.
4) The high rate of fault movement conflicts with the
interpreted top of the Prairie Terrace accepted by most
workers. Is the second weathered surface and not the first
weathered surface in the lake truly the top of Prairie
Terrace?
Some of these questions may be academic and others may have more civic
significance, but all of these and others can be addressed with further
basic research. Much can be gained by research efforts by greater
exchange of data and ideas between professionals which generally operate
in different institutional or commercial spheres.
Otvos, E. G., Gulf Coast Research Laboratory, Ocean Springs, MS
39564-7000, LAKE PONTCHARTRAIN BASIN EVOLUTION; LATE
PLEISTOCENE-HOLOCENE GEOLOGICAL HISTORY.
The Pleistocene sedimentary cycle that preceded Holocene evolution
of the lake system, climaxed 128-122 ka B.P.during the Sangamonian
Interglacial. It produced the muddy-sandy, microfossil-rich,
marine-to-estuarine Biloxi Formation, c. 13.5 m thick under
Fontainebleau State Park and south Hancock County, MS, and overlain by
the thin regressive alluvial Prairie unit. The oxidized, seaward-sloping
Prairie coastwise surface, cut by approximately E-W-trending faults,
forms the northern border of the Lake. A buried segment of the Gulfport
barrier complex, the Gulfwide Sangamonian high shoreline indicator,
occurs at nearby Port Bienville, MS. The previously reported presence of
another Pleistocene segment beneath the Lake, c. 10 km from the north
lake shore, is not yet proven. (Earlier, this 3-5 m thick sand body,
appearing as channel-filling beneath the muddy lake deposits in the
Causeway foundation-drillholes, has been described as the "Miltons
Island Beach Trend", Saucier's assumed earlier Holocene lake shoreline.)
Stream channels became deeply incised in the general area and clusters
of wind-blown dunes formed along river floodplains in the Florida
Parishes during subsequent marine lowstands of the Wisconsinan glacial
interval. By c. 4.5 ka B.P., Holocene transgression filled most of the
"Pontchartrain Embayment" with higher salinity but still brackish
waters. Westward-directed littoral drift from Pearl River delta shores
5.0 -3.7 ka constructed a chain of sandy underwater shoals, probably
also including small barrier islands in front of the embayment. These
barrier sand bodies are 6-12 m thick. Occasionally, they extend near,
even slightly above the land surface (Pine and Oak "Islands" in New
Orleans East).
Sediment and microfossil data marked steady eastward growth of the
Mississippi delta toward the shoals. A delta spur separated Lake
Maurepas from Pontchartrain. By 4.0 ka, the Morrison Rd. Pit area (at
Frenchmans Wharf Apartments, on Interstate Highway 10, New Orleans
East), was covered by subdelta clays and sandy muds (Otvos, 1978).
Recently obtained radiocarbon dates (Dr. F. Stapor, Jr.) indicate that
shore processes continued 4 km to the east at Bullard Rd. until c. 3.5
ka. As late as 3100-2900 yr B. P. barriers of the separate South
Hancock-Sauvage trend were active shore zones in easternmost Orleans
Parish.
Intensive regional delta growth (St. Bernard and other subdeltas
in present Orleans-St. Bernard Parishes) subsequently buried the two
barrier trends under the extensive marshlands. Pontchartrain's waters
freshened as a wide belt of delta land gradually cut off the bay from
the Gulf. Lake beaches and numerous Indian midden mounds date from this
period. Cessation of delta growth and continuing subsidence soon
increased shore erosion. Improved connection with the Gulf, most
recently through the man-made Gulf Outlet Channel, slightly increased
salinities. Intensive commercial clam shell-dredging in recent decades
(Otvos and Sikora, 1990) liquefied central lake sediments and profoundly
impacted bottom biota, including the Rangia bivalve fauna. Lake tidal
gage data indicate minor subsidence probably along faults. Tectonic and
eustatic changes, sediment compaction and marsh degradation -related to
natural and man-induced causes- will remain critical factors in future
basin development.
William S. Perret, L. Brandt Savoie, John F. Burdon and Karl A. Mapes.
Louisiana Department of Wildlife and Fisheries. The Fisheries of the
Pontchartrain Basin.
the Lake Pontchartrain Lacustrine Basin is bordered by 8 parishes
and drains 8 additional parishes of Southeast Louisiana and numerous
counties of southwest Mississippi. Preliminary data indicate that in
1990, -*-% (-*- pounds) of Louisiana's commercial fishery landings were
within the basin. Historical records indicate that the Basin has
contributed significantly to the states fishery production. Landings
include species caught from freshwaters to adjacent continental shelf
waters of the Gulf of Mexico.
In 1990 a significant number od commercial and recreational
fishermen resided within the Basin. Freshwater recreational fishermen
from the Basin accounted for 22% (108,107) while saltwater anglers
accounted for 42% (88,331) of the states licensed resident population.
commercial licenses sold within the Basin accounted for 31% (32,612) of
the state's total.
Utilization of the Basin's fishery resources by recreational and
commercial groups have continued to increase during the last three
decades but overall fishery production has not kept pace. While
landings may have increased in some cases, the addition of more user's
has resulted in a decreased catch per effort.
The Basin's fishery has been significantly impacted by wetland and
estuarine habitat loss or modification due to such activities as
leveeing, reclamation, subsidence, sea level rise, erosion, toxins and
eutrophication. Salinity modifications often accompany habitat
modifications and may significantly impact the distribution of fishery
species. Point and non-point source discharges of pollutants have
impacted the quality of the harvest waters of many species, especially
the American oyster. Introduction of species or pathogens not endemic
to the Basin may also pose a threat to the fisheries.
Its diverse habitats and resources portray a region that is
providing adequate fishery production, despite its problems. However,
it evident that there are many significant economic and social changes
occurring with more on the horizon. Sustaining or enhancing the fishery
resources of the Basin has no single solution. conservation,
implementing comprehensive wetland management plans, implementing
comprehensive inventories of habitat types, and strengthening the
environmental consciousness of all who live, work and play in the Basin
will help.
*Landing data is forthcoming for NMFS.
Powers, S.P., Poirrier, M.A., and Yund, P.O., Department of Biological
Sciences and the Urban Waste Management and Research Center, University
of New Orleans, New Orleans, Louisiana 70148. THE EFFECTS OF NEW ORLEANS
URBAN RUNOFF ON THE BENTHIC COMMUNITY OF SOUTHERN LAKE PONTCHARTRAIN.
Between the summer of 1991 and the winter of 1992 we conducted a
study of the benthic community of southern Lake Pontchartrain to assess
the impact of New Orleans urban runoff on Lake Pontchartrain. A sampling
grid, which extended North from the shoreline eight kilometers and 5
kilometers East to West, was established in southern Lake Pontchartrain
adjacent to three outfall canals in Jefferson Parish (Parish line,
Duncan, and Elmwood canals). Two macrofauna and two meiofauna samples
were taken from sets of sites within the sampling grid between June 1991
and February 1992. Differences in species diversity, abundance,
dominance, and trophic structure among sites were analyzed to assess the
effect of the outfall canals on the benthic community.
Results from our study indicate that there is a pronounced effect
on the communities immediately adjacent to the outfall canals
(0m-400m(?)). These sites were characterized by low species diversity
values, reduced numbers of mollusks (particularly juveniles), and
increased abundance of nematodes, oligochaetes, and capitellid
polychaetes on all sampling dates. A transient effect was also seen in
the meiofauna community following a period of high rainfall. This short
term effect extended much further than the chronic effect (2.40 km) and
was probably a result of the large input of freshwater into the lake. We
also compared the effects of three different canals, which differed in
discharge capacity and levels of toxins, on the associated benthic
communities. A comparison with previous benthos surveys allowed us to
evaluate the effect of sewage diversion into the Mississippi River,
initiated in 1989.
Preston, K.P., Geography/Urban Waste Management and Research Center
(UWMRC), Poirrier, M.A. and Burns, J.W. Biological Sciences/UWMRC,
University of New Orleans, New Orleans, LA, COMMUNITY STRUCTURE AND
DISTRIBUTION OF SUBMERGED AQUATIC VEGETATION IN LAKE PONTCHARTRAIN,LA.
Submerged aquatic vegetation (SAV) generally occurs along the shallow,
less exposed shoreline areas in the Lake Pontchartrain Basin and
provides a number of important ecological functions. Submerged
grassbeds help stabilize sediments, reduce shoreline erosion, assimilate
pollutants, and release oxygen. Moreover, they provide a protected
habitat for larval and juvenile stages of many estuarine organisms and a
food source for waterfowl, fish, invertebrates, and other aquatic
species. Over the past 40 years several studies have noted a decrease
in grassbed coverage and a decrease in depth of grassbed growth. Areal
coverage of SAV in Lake Pontchartrain has decreased by 50% between 1973
and 1983. While previous studies provide general qualitative
information about the status of grassbeds in Lake Pontchartrain, they
provide little quantitative information concerning community structure
and diversity and seasonal variation in growth and distribution.
Moreover, they fail to take into account the patchy nature of grassbed
distribution when estimating areal coverage thus likely overestimating
the actual coverage of SAV beds in Lake Pontchartrain.
In this study species composition, community structure, and diversity
relations were determined for five grassbed sites in Lake
Pontchartrain. Foliar cover of all SAV species was measured along five
randomly placed transects in each site during the summer of 1991. The
measurements were repeated during the winter of 1992 along a random
subset of transects at each site. The seasonal variation in SAV
distribution and the degree of deciduousness among the dominant species
could thus be ascertained. Foliar cover for each species was stratified
by depth interval and substrate type along each transect in order to
identify the influence of these physical variables on SAV growth. In
addition, the degree of patchiness within grassbeds was used to modify
estimates of grassbed coverage in Lake Pontchartrain.
Rheams, Anne B. Louisiana Department of Environmental Quality, Baton
Rouge, La., LAKE PONTCHARTRAIN BASIN:URBAN NONPOINT SOURCE POLLUTION
PROBLEMS AND SOLUTIONS.
Recent water quality monitoring studies in urban areas have shown
that the highest pollutant loadings and concentrations usually occur
during rainfall events in the first 0-1 inch of rain, commonly referred
to as the "first flush." In urbanizing an area, impervious surface-area
such as streets, parking lots, and rooftops is increased. These smooth,
impenetrable surfaces allow little or no detention or infiltration of
stormwater. As precipitation falls on urban areas, it picks up
contaminants from the air, littered and dirtied streets and sidewalks;
petroleum residues from automobiles, exhaust products, heavy metals and
tar residuals from the roads; chemicals applied for fertilization, weed
and insect control; and, sediments from construction sites. The dumping
of chemicals such as used motor oil and antifreeze into storm sewers is
another source of urban nonpoint source (NPS) pollution.
Lake Pontchartrain is severly impacted by urban runoff and has been
targeted as a priority watershed within the Department of Environmental
Quality's (DEQ) Urban NPS Program. According to the state's 1990 Water
Quality Inventory (305(b) Report) and the 1991 NPS Assessment Report,
Lake Pontchartrain ranks second in the state in total water quality
management subsegments impaired and/or threatened by urban runoff. This
information is based on evaluative data from the DEQ regional offices
and specific water quality monitoring stations in the basin.
In addition to the need for physical, corrective measures such as
best management practices (BMPs) to prevent and reduce urban NPS
pollution, source control through public education regarding NPS
problems and solutions is critical to urban NPS pollutant abatement.
DEQ's urban NPS public education and involvement strategy includes the
dissemination of educational materials such as brochures, posters, fact
sheets, and bumper stickers. DEQ's Storm Drain Stenciling Program has
been initiated in both Jefferson and Orleans Parishes in an effort to
alert basin residents of the connection between storm drains and the
water quality of the lake. The purpose of the stencil program's message
is to serve as a deterrent to people who dump pollutants such as used
motor oil down storm sewers, not knowing that the sewers drain directly
into the lake instead of a wastewater treatment facility. Other
educational and technical assistance activities include an urban NPS
video, a model ordinance report, establishment of WATERWATCH groups, and
a lawn care demonstration project.
DEQ's Urban NPS Program includes a task for the implementation of
urban BMPs and the evaluation of their effectiveness in improving water
quality. DEQ is accepting proposals for BMP projects in priority w
atersheds such as Lake Pontchartrain.
While the Urban NPS Program's strategy for implementation is
non-regulatory, many of the problems related to pollution from urban
runoff will be addressed through EPA's stormwater regulations. Both
Orleans and Jefferson Parishes, bordering the south shore of the lake,
are in the process of applying for stormwater permits.
Rohli, R.V., Southern Regional Climate Center, Department of Geography &
Anthropology, Louisiana State University, Baton Rouge, LA, DEVIATIONS
BETWEEN MODELED AND MEASURED RUNOFF IN THE LAKE PONTCHARTRAIN BASIN.
A Thornthwaite monthly water-budget model is used to estimate monthly
surface runoff into the Lake Pontchartrain Basin from the Comite, Amite,
Tickfaw, Natalbany, Tangipahoa, and Tchefuncte Rivers for the last fifty
years. The modeled outputs for each drainage basin are compared to
measured monthly runoff data obtained from the U.S. Geological Survey
for the same time periods. Statistical tests are implemented to
identify those basins where seasonal and annual ratios of modeled to
measured runoff differ significantly from each other. Hypotheses about
the differences are developed, and model adjustments are recommended for
better estimation of runoff from ungaged areas of the Pontchartrain Basin.
Sabate', R.W., The San'Doil Co., New Orleans; Dewailly, E.L., Lumitox
Gulf, New Orleans; Stiffey, A.V., University of New Orleans: ALGAL
BIOLUMINESCENCE IN TOXICITY TESTING
Environmental quality commonly is determined by bioassays, which measure
the response (primarily death rate) of living organisms to the presence
of toxins. Subject organisms range from indigenous populations to
selected species with demonstrated standard responses, predominantly
minnows and shrimp. Cumbersome culture facilities and laboratory
techniques, which translate to time and expense, together with the
desire for on-site testing, has led to experimentation with monocellular
species. These offer the added statistical advantage of larger numbers
(thousands or hundreds vs tens) of individuals in a sample aliquot.
Lumitox (R) is a new, compact, fast (hours vs days) patented bioassay
that uses the marine bioluminescent dinoflagellate alga Pyrocystis
lunula. When agitated, P. lunula generates a brilliant flash of light.
In the presence of varying concentrations of toxins, this light - as
measured by a patented photometer - is quenched in a predictable
manner. The procedure is very sensitive to small changes in toxic
concentrations both at high and low levels, is repeatable with low
variation, and is effective in turbid or colored media.
The U.S. Navy inventor of Lumitox (R) has demonstrated its testing
efficacy with many substances, including pesticides, defoliants, marine
antifouling paint, waterbottom samples, and oil-well drilling fluids,
the latter confirmed by Louisiana State University. In conjunction with
University of New Orleans, Lumitox (R) will engage in environmental
testing and develop a portable testing unit.
Smith, Sue K., Louisiana State University, Baton Rouge, La., NORTH-SHORE
SOURCES OF SUSPENDED SEDIMENT IN THE SURFACE RUNOFF TO LAKE PONTCHARTRAIN.
The Lake Pontchartrain Basin in southeast Louisiana comprises
Lakes Pontchartrain and Maurepas, along with the surrounding land area.
The major north-shore streams that contribute fresh water into the basin
are the Amite, Tickfaw, Tangipahoa, and Tchefuncte river systems, along
with their tributaries. These streams head in southern Mississippi and
flow southward across a series of down-stepping terraces through a
region that is used mostly for agriculture and forestry. Hydrologic
data are available for approximately 50 years for these streams. The
data show some variations in stage, discharge, and water quality.
Suspended sediment data show distinct differences between the seasons of
the year and between the different rivers. During this time period,
some of the streams have also shown some changes in their planform
dimensions. The nature of these variations and changes are discussed,
and some possible explanations are offered.
Thiyagarajah, A., and Ledet, M. J., college of Pharmacy, Xavier
University of Louisiana, 7325 Palmetto Street, New Orleans, LA
HISTOPATHOLOGICAL ASSESSMENT OF TWO SPECIES OF FISH FROM THE BAYOU
TREPAGNIER.
Bayou Trepagnier is located in the Lake Pontchartrain Basin, in St.
Charles Parish of Louisiana. Bayou Trepagnier receives treated
wastewater and storm water from an oil refinery and manufacturing
complex. According to the Water Pollution Control Division of the
Louisiana Department of Environmental quality reports, benzene, toluene,
ethylbenzene, dichlorobenzene and chloroform were detected in fish and
crabs collected from the lower stations on Bayou Trepagnier. Benzene is
classified by USEPA as a known human carcinogen. The purpose of this
preliminary study is to assess the fish health histologically. We
selected mollies (Poecilia latipinna) and sheepshead minnows (Cyprinodon
yariegatus) as test organisms because these species are very sensitive
to carcinogens. Fish were caught by beach seine twice in November,
1991. Fish were examined grossly, and then processed for histological
assessment. Preliminary observations indicate that the majority of the
lesions are present in the cartilage, muscle, liver, and pancreas.
Liver lesions range from fatty change to precancerous lesions. The
preneoplastic lesions include basophilic cell foci, vacuolated cell
foci, clear cell foci, and spongiosis hepatis. Other lesions include,
fatty change in the exocrine pancreas, fat necrosis, vasculitis,
protozoan and metazoan parasites in various tissues, and inflammatory
lesions. These lesions will be described and discussed.
Thompson, Bruce A., Coastal Fisheries Institute, Louisiana State
University, Baton Rouge, Louisiana 70803-7503, A REVIEW OF FISH STUDIES
ON LAKE PONTCHARTRAIN.
Many questions have been asked over the years about the fish assemblages
of Lake Pontchartrain. The members of this 130 species assemblage play
important roles in both the ecology and economics of the region. Over
the past 40 years there have been four major, multi-gear, year-long
studies of the fishes of Lake Pontchartrain; two in the 50's, and two in
the 70's. The last fish survey was done during 1978, 14 years ago! The
relative abundance of many common fish species in the lake has changed
little between 1953 and 1978 and no change in the community proportion
of marine, estuarine or freshwater fishes was found. The lake serves a
major function as nursery and feeding grounds for large numbers of
juvenile fishes. Certain environmental changes may be impacting the
lake's ability to continue to function as a major nursery. The salinity
regime of the lake, controlled primarily by riverflow, seems to control
which fish species will be dominant. Overall, the fish assemblage
appears to have a "healthy" indication of seasonal change and a lack of
overdominance as found in more disturbed estuarine systems.
Thomson, A., University of New Orleans, New Orleans, La., and LeBlanc,
R.J., Sr., Rufe LeBlanc School of Clastic Sediments, Houston, Tx.,
GEOLOGICAL HISTORY OF LAKE PONTCHARTRAIN.
The Lake Pontchartrain Basin of southeastern Louisiana lies between the
Late Pleistocene Prairie Terrace to the north and the Late Holocene
Mississippi Deltaic Plain Complex to the south, a distance of about 28
miles. The western margin of the Basin is near the present Mississippi
River southeast of Baton Rouge, and the eastern margin of the Basin is
near the western end of the Mississippi Sound. Thus, the width of the
Basin is about 90 miles.
Lake Pontchartrain is the largest lake within the Basin. It has an
areal extent of about 700 square miles and lies to the east of Lake
Maurepas and the west of Lake Borgne. The areal extent of these three
lakes comprises more than half of the Basin.
Considerable research on the geology of the Pontchartrain Basin was
conducted over a period of over 40 yrs (1935-1977) by several Louisiana
State University Geology professors and their graduate students and
former students, with funds provided by the Corps of Engineers and
several oil companies. None of this research has produced any evidence
that the area encompassed by Lake Pontchartrain was once an extensive
deltaic plain.
Research results indicate the origin of the Pontchartrain Basin was
different from the origin of Lake Pontchartrain within the Basin.
Sub-regional tectonic processes (faulting and subsidence) were mainly
responsible for the development of the Basin. In contrast, Lake
Pontchartrain originated as a result of sedimentation processes. After
the last rise in sea level reached its present stand about 5000 years
ago an arm or embayment of the Gulf of Mexico extended inland as far
north as the latitude of Mandeville, La. Later the western portion of
the embayment was isolated from the Gulf by arms of the Cocodrie and St.
Bernard Deltas of the Mississippi River, producing Lakes Maurepas and
Pontchartrain. Thus, in spite of subsidence and some down-faulting
within the embayment, the Mississippi River overwhelmed the region with
sediments, and Lake Pontchartrain remains isolated from the Gulf, with
the exception of the narrow Rigolets outlet into Lake Borgne. After the
St. Bernard Delta was abandoned, the trunk course of the present
Mississippi River contributed little sediment to the lake.
In conclusion, it is highly probable that faulting within the
Pontchartrain Basin (south of the Pleistocene Terrace) has played a
minor role in the origin and development of the lake, but there is
overwhelming evidence that Lake Pontchartrain was created as a result
of Mississippi River diversion and sedimentation.
Turbeville, J.H.Jr., Conoco Inc., New Orleans, La., THE GEOLOGY AND
GEOHYDROLOGY OF AN AREA REPRESENTATIVE OF NEAR SURFACE AQUIFER SYSTEMS
ON THE MISSISSIPPI RIVER FLOOD PLAIN IN SOUTH LOUISIANA.
The Mississippi River Flood Plain is approximately 100 miles wide,
extending from Lake Pontchartrain to Lafayette, and traversing the
entire state of Louisiana from north to south. The near surface aquifer
system created on the floodplain coincides with both the most heavily
industrialized and environmentally sensitive areas in the state. This
includes the great majority of Lake Pontchartrain and wetland areas.
The study area is located outside of Luling, Louisiana, between the
cities of New Orleans and Baton Rouge. It is 1/2 mile south of the
Mississippi River and 10 miles southwest of Lake Pontchartrain. Located
on an industrial park, the area encompasses two separate sources of
known dichloroethane contamination (a dense non-aqueous phase liquid or
DNAPL), the Ethylene Maleic Anhydrite (EMA) and Deep Well Pond sites.
There were 23 wells used in the study that penetrate four stratigraphic
layers. Layers I and III are considered to be aquitards, layers II and
IV are aquifer sands. The aquifer system interval ranges from 2' to 40'
measured from ground surface.
Stratigraphic correlations of the aquifer system were completed by
constructing a series of cross-sections (10) across the area. A total
of 7 geologic maps were then generated on the base, top and thickness of
each aquifer unit. A hydraulic gradient map was constructed, and
coupled with hydraulic conductivities (from slug tests), average linear
velocities of groundwater were calculated.
The penetrated stratigraphy is from Holocene to Recent in age and
consists of 4 units. Layers I and III are organic rich clays deposited
as part of the natural levee system. Layers II and IV are silt to
coarse grained sands in fining upward sequences deposited as overbank or
swale fill that vary in proximity and source direction from the
Mississippi (or paleo Mississippi) River. Maximum vertical relief is
created on the flood plain from the natural levee systems, which
vertically accrete until the river overruns the levee and eventually
abandons the channel.
Both layers II and IV are partially confined aquifers that are
moderately heterogeneous with respect to hydraulic conductivity.
Hydraulic conductivity values are relatively low and range from .1 to 3
ft/day, increasing to the south and in the basal portions of layers II
and IV. Groundwater flow direction averages southwest, with a hydraulic
gradient averaging .0036. The Mississippi River is thought to be a head
boundary that fluctuates with the rivers stage.
Groundwater velocity is relatively slow with a calculated range from
.001 ft/day to .04 ft/day, increasing to the south of the study area.
This is considerably slower than what is observed in areas of known
contamination in the EMA and Deep Well Pond areas. Contaminant
dispersion (spreading out) appears to be a significant factor based upon
contaminant plume delineation from soil vapor analysis relative to known
source area.
There is potential for DNAPL contamination to follow the structural base
of layers II and IV, thereby retarding or accelerating migration
velocity, depending on its directional relationship to groundwater
flow. Sharp basal contacts created from fining up sequences in both
layers enhance this effect.
Vega, A. J., Southern Regional Climate Center, Department of Geography
& Anthropology, Louisiana State University, Baton Rouge, LA, 70803,
LONG-TERM CLIMATIC VARIABILITY OF MODELED AND MEASURED RUNOFF WITHIN THE
LAKE PONTCHARTRAIN BASIN.
This study examines long term climatic variability of modeled and
measured runoff within the Lake Pontchartrain Basin. Runoff estimates
will be determined using a Thornthwaite water-budget model for the
Comite, Amite, Tickfaw, Natalbany, Tangipahoa and Tchefuncte Rivers.
Time series analysis will be employed to determine yearly, seasonal and
monthly climatic trends in association with individual water years
(October to September). Long-term trends will be accessed for each of
the drainage basins and collectively to determine patterns of climate
variability (i.e. wet or dry months, seasons, years). This analysis
will determine associations between the frequency of extreme temporal
precipitation events and global circulation variability.
Wee, James L., Booth, Dennis J. and Bossier, Michael A., Department of
Biological Sciences, Loyola University, New Orleans, Louisiana,
Synurophycean Algae from the Lake Pontchartrain region: A Preliminary
Survey from the Southern Atlantic Coastal Plain of North America.
Forty-three taxa of Synurophyceae were identified by means of
transmission electron microscopy from 10 samples collected in
southeastern Louisiana, USA, on the southern portion of the Atlantic
Coastal Plain Province of North America. Mallomonas prora and Synura
australiensis are reported for the first time from North America.
Samples were collected during a one month time period when water
temperatures ranged from 15.5-24.5 C. Sample pH values ranged from
4.42-7.21. Notable scale morphology variation was described for some
taxa. The flora included three warm water taxa but was dominated by
temperate and cosmopolitan taxa. Comparisons with related studies from
New World, subtropical regions in Florida, USA, and Argentina, were
made, and significant North American range expansions were noted. The
large number of aquatic habitats, 7-8 consecutive months at temperatures
(6-20 C) best suited for development of synurophyte populations, and
proximity to major bird migrations routes are postulated as explanations
for the large number of reported species.