Conservation of Texas Bays and Estuaries
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Conservation of coastal waters and wetlands is intrinsically tied to recreational activities like fishing, hunting, birding and boating. The health of the coastal economy is also tied to the health of the coastal zone. Adequate supplies of clean, fresh water carrying nutrients and sediments to many different coastal wetland habitats like saltmarshes and seagrass beds are essential for economically and ecologically important species of fish, birds and wildlife [Map 23]. As the state agency with responsibility for regulating both commercial and recreational fishing in marine waters, TPWD continually conducts scientific investigations to protect and conserve marine life.
Priority Bay and Estuary Systems
All bay and estuary systems along the Texas coast have great commercial, recreational and conservation value. Each bay has numerous conservation threats that are specific to that system. All systems face conservation challenges to varying degrees, and a specific issue can quickly change priorities and increase the importance of conservation action. The greatest long-term threat to the health and productivity of these systems is diminished freshwater inflows. For many the more immediate challenges include habitat loss, poor water quality, fisheries management conflicts and related issues. The bay systems were evaluated using information compiled from the Shrimp Habitat chapter of the Draft Texas Shrimp Fishery: A Report to the Governor and 77th Legislature. Each bay system was evaluated using the following categories: development, petrochemical production, substrate alterations, exotic species, fishing, water quality, point-source pollution, non-point source pollution and numerous sub-categories (a total of 22 elements). The bay systems were prioritized as High Priority Systems or Priority Systems below [Map 24]. It is difficult not to include most, if not all of bay and estuary systems as a high priority. However, it is important to identify those systems where immediate attention can be most beneficial the fish and wildlife management responsibilities of TPWD.
High Priority Systems
Galveston Bay System
Galveston Bay is the largest
estuary on the Texas coast.
It is part of the National
Program and faces the greatest conservation challenges of any system. This complex is adjacent to the most populated and industrialized area of the state. Suburban and industrial development are reducing critical wetland habitat at a faster rate than anywhere else along the coast. The majority of Texas’ hazardous chemical spills and the largest oil spills occur in this system. Both domestic and industrial wastewater also flow into the bay. Periodic dredging of the channel and bycatch associated with commercial harvest are significant conservation threats to this bay. Exotic species like Chinese tallow, giant salvinia, water hyacinth and grass carp also threaten native habitats throughout the bay. The regional water plan recognizes the importance of freshwater inflows to the bay, but strategies to legally preserve inflows have not been identified.
Matagorda Bay System
The Matagorda Bay system
includes the Matagorda Peninsula
and the Colorado River Delta.
It is home to one of the
largest shrimp fleets on
the coast. The bay is very
popular with recreational
anglers and commercial fishing
fleets, resulting in excess
targeted species and bycatch. Mercury contamination from large smelting operations in the 1970s and 1980s in Lavaca Bay is often exacerbated by frequent dredging activity. Currently, management of inflows is inadequate to protect the bay during water shortages, but further inflow studies are needed to improve management strategies.
Corpus Christi Bay System
The Corpus Christi Bay is also in the National Estuary Program. The primary sources of freshwater inflow are Oso Creek and the Nueces River. However, reservoir construction, increased population and industrial growth in the area have greatly reduced freshwater inflows in this already arid region. Reduced inflows have contributed to salinization of the delta and shoreline erosion. Extensive recreational and commercial fishing cause overharvest and excess bycatch of non-targeted species. Intense industrial, commercial and shoreline development has affected Corpus Christi Bay. Dredging the Intercoastal Waterway and spoil disposition also harm water quality of the system.
San Antonio Bay System
The San Antonio Bay system consists of the primary bays San Antonio and Espiritu Santo and the secondary bays Hynes, Guadalupe and Shoalwater. Several large natural saltwater lakes occur along Matagorda Island and connect with the primary bays via sloughs and small passes. Threats to San Antonio Bay system come from the commercial harvest, trawling and inadvertent bycatch of non-target species, dredge and fill operations along the Intercoastal Waterway and the lack of adequate freshwater inflows.
Sabine Lake System
Sabine Lake makes up the southern border between Texas and Louisiana. It is adjacent to one of the largest petrochemical producing complexes in Texas and both industrial and domestic wastewater are discharged into the Sabine Lake system. Water quality and aquatic health in Sabine Lake has improved since the introduction of the Clean Water Act in 1972 and subsequent regulations. Threats to the system include industrial and commercial development along the shoreline, operation of petroleum and chemical plants and general non-point source pollution primarily from agricultural lands. Gulf waters and tidal streams experience low oxygen levels following tropical storms. Other threats include the proposed dredging of the Sabine-Neches Waterway, increasing salinities that damage wetland habitats and the exotic plants that clog tidal streams and channels.
Lower Laguna Madre Bay System
The lower Laguna Madre is a long shallow bay extending from Port Isabel to the Kennedy Land Cut. The Arroyo Colorado and North Floodway are the main freshwater inflow sources for the bay, which is also hypersaline. Rapid population growth in the Lower Rio Grande Valley is affecting the bay system. As with the upper Laguna Madre, dredging, spoil removal and the presence of excess nutrients are primary threats. High nutrient concentrations come from municipal and industrial discharges, agricultural runoff and discharged wastewaters from the largest shrimp farms in the United States. Another serious concern is that there is currently no connection between the Rio Grande and the Gulf because there is not sufficient freshwater inflow, while exotic plants are constricting the river.
Texas Territorial Sea
The Texas Territorial Sea is that portion of the Gulf of Mexico extending seaward from Texas’ Gulf shoreline out to nine nautical miles. Extensive oil, gas and petrochemical production, marine commerce and transportation are major industries that utilize the Texas Territorial Sea. It is widely used for commercial shrimp trawling, menhaden trawling, longlining, recreational fishing, oil and gas production and recreational scuba diving. Threats to this nearshore gulf area and its associated marine organisms include potential oil and chemical spills, over-harvest of shrimp, finfish and other marine species, bycatch of fish, invertebrates and sea turtles and damages from the hypoxia, or reduced oxygen zone, and harmful algal blooms.
Aransas Bay System
The Aransas Bay complex extends from Aransas Pass to Bayside. Aransas Bay supports an extensive commercial fishery comprised of shrimp, crab, oyster and finfish species. The intense fishing pressure, both recreationally and commercially, threaten the health of the bay. Freshwater inflows are often inadequate to support the rich species diversity in the estuaries and bay area. In addition, the Texas Department of Health has closed several shoreline areas of the bay to all shellfishing because of inadequate sewage treatment.
Upper Laguna Madre System
Located on the lower Texas coast, the upper Laguna Madre system consists of upper Laguna Madre and Baffin Bay systems. The system is a long, narrow and shallow lagoon, bordered on the east by Padre Island and on the west by Corpus Christi. The surrounding areas have very little development and industrialization. The upper Laguna Madre, with no constant openings into the Gulf of Mexico and limited freshwater inflow, is characterized as a hypersaline estuary. The substantial source of freshwater is runoff from various watersheds into Baffin Bay. In the 1990’s, the bay regularly experienced brown tide that increased turbidity and reduced seagrass beds and also negatively impacted tourism and recreational fishing. Dredging, moving the spoils and excess nutrient runoff threaten extensive seagrass beds and may be responsible for harmful algal blooms.
Important Aquatic Habitat Types for TPWD Efforts
As with prairies and riparian habitats on land, there are important, natural water-based resources that cross all ecoregion, river basin and bay system boundaries. These resources are important for wildlife, water quality and quantity and other conservation values and also warrant priority effort by TPWD.
Springs and Aquifers
Groundwater systems in Texas are diverse. Rainfall can be taken up by plants, evaporate over time, form runoff into streams, rivers and estuaries, or it can become groundwater by seeping into soil, sand and other land features. Water that moves into groundwater is recharge. Ground formations that store and transport enough water for human use are aquifers.
Springs are the natural outlets of aquifers. Springs that have run dry have had profound effects on surface water because they often form the base flows that sustain rivers and streams during drought. It is difficult, if not impossible, to restore aquifers that have been drawn down and continue to have withdrawals that greatly exceed the available recharge, but it is possible to conserve springs that depend on aquifers that recharge quickly.
Wetlands in Texas
Wetlands are among the most important habitats in Texas. These interfaces between water and land are integral in supporting a vast array of plants, fish and wildlife. They also perform numerous valuable functions: they trap water, sediments and nutrients and therefore play a major role in improving water quality and decreasing pollution. They are invaluable for their ability to prevent and minimize flooding, protect shorelines and replenish groundwater sources.
Texas has lost thousands of acres of historic wetlands, while human activities, including landscape alteration for agricultural, industrial or urban uses, significantly threaten remaining wetland habitats. Subsurface mineral and water extraction can also destroy wetlands, especially along the coast. Overharvest of timber threatens wooded wetlands as is evidenced in the state’s bottomland hardwoods, pine flatwoods and swamps. Reservoir construction can submerge wetland areas upon filling, or they may be destroyed by diverting or capturing their source of water. Along the coast, reduced flow in rivers and streams can cause loss of freshwater wetlands due to increased saltwater intrusion. In the Panhandle, increased siltation from natural and agricultural erosion threatens playa lakes, which are important habitat for waterfowl and many other wildlife species.
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