Baseline
Assessment of Instream and Riparian Zone Biological
Resources and Establishment of Benchmark Stations
in the Big Thicket National Preserve, Texas
Contents
HISTORY
The Big Thicket National Preserve
(96,669 acres) has a highly fragmented land base
of nine units connected by four riparian corridor
units. The U.S. Congress recently authorized two
additional riparian corridor units and one land-based
unit that are expected to become part of the the
Preserve in the near future. The two units form
a narrow buffer zone around Village Creek, considered
one of the best canoeing streams in southeast
Texas.
Although the region around the
preserve is largely forested, a trend of increased
urbanization and industrialization is emerging.
Over the past 10 years, there has been a regional
decline in dissolved oxygen levels in streams
of southeastern Texas. As cities within the region
expand, point-source pollutants from increases
in sewage treatment plant effluents could further
reduce dissolved oxygen levels.
Industrial point-source pollutants also are an
issue in the preserve. In 1986 - 87, as part of
the National Bioaccumulation Study, the U.S. Environmental
Protection Agency documented toxic levels of dioxin
in fish tissue samples from the lower Neches River
Corridor Unit in the Big Thicket National Preserve.
The Texas Department of Health (TDH) issued a
fish-consumption advisory for this reach on the
lower Neches River, which remained in effect until
1996. The TDH continues to monitor the situation.
Historically, the most important point-source
impacts on stream in the preserve have been from
oil and gas operations. In 1981, for example,
an oil spill adjacent to the Turkey Creek unit
flowed into a nearby tributary and eventually
into the preserve. Although the spill was quickly
contained, it nearly extirpated the benthic marcoinvertebrate
community along the entire stream reach. More
recently, innovations in three-dimensional seismic
surveying technology have spawned an unprecedented
wave of oil and gas prospecting throughout the
preserve. The preserve resource managers are concerned
about the potential impacts to aquatic resources
from these operations.
OBJECTIVES AND APPROACH
- Provide a baseline assessment of the status of instream biological resources and riparian zone woody vegetation throughout the Big Thicket National Preserve
- Establish a network of permanent biomonitoring benchmark stations to compliment historical and planned basic water-quality monitoring stations and provide the data to develop a predictive tool for assessing the status of instream biological resources
- Provide the Big Thicket Preserve with watershed delineation, basin characteristics and land-use characteristics for all subwatersheds and permanent benchmark monitoring stations
The baseline assessment of the biological resources in
the preserve will be conducted and will include
assessment of (1) channel habitat; (2) fish; (3)
benthic invertebrates; (4) riparian woody vegetation.
The information from this synoptic assessment will
be used to (1) compile an inventory of these resources
for the preserve; (2) establish permanent monitoring
stations to include reference condition, and, for
the more degraded stations, document biological
impairment and watershed land use in the preserve;
and (3) to provide site-specific biological resource
data, physical basin characteristics and land-use
information in the drainage upstream of each site.
WHAT'S
TO BE GAINED
Combined with past water-quality
monitoring efforts, this study should provide
a baseline of water-quality information from which
to detect future change. A synoptic biomonitoring
study will benefit management of the preserve
in several significant ways. First, the study
will provide the preserve with a comprehensive
and current inventory of aquatic fauna for the
existing units and the first-ever inventory of
aquatic fauna for the new units. The last fish
inventory for the existing units was done 20 years
ago, and no comprehensive inventory of aquatic
fauna has ever been done. The biomonitoring effort,
however, will yield more than just an updated
inventory. It will be the first step in developing
a predictive tool for assessing how changes in
land use in the surrounding watersheds can potentially
impact the running waters of the preserve. Instead
of reacting to degraded waters, the preserve managers
eventually will be able to manage proactively
by knowing beforehand how land use changes will
affect aquatic biota. This information is critical
for resource managers to work effectively with
stakeholders within the watersheds and reduce
impact to aquatic resources. The methods and knowledge
gained from this study also will be readily transferable
to other National Park Service units with similar
issues.
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Big Thicket National Preserve - Biological
Crossroads of North America
Once vast, this
land of virgin pine and cypress forest, hardwood
forest, meadow, and blackwater swamp is but
a remnant. |
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U.S. Department of the Interior |
U.S. Geological Survey
