Have you ever wondered why San Antonio Bay is the ultimate spot on the Texas coast for great recreational fishing and duck hunting? Areas of extensive shallow water habitat cover the bay bottom and are utilized by fishes at all stages of life. These benthic habitat types vary along the Texas coast and include wetlands, oyster reefs, seagrass, tidal and mud flats. They provide spawning grounds, food and shelter for many commercially and recreationally important species. These benthic habitats are not only utilized by fishes and other aquatic organisms but also by waterfowl and migratory bird species as resting, breeding and feeding grounds. The most common type of benthic habitat is open, muddy bay bottom. These areas do harbor marine life, but not nearly to the extent of other habitat types. Open bay bottom dominates San Antonio Bay but other important benthic habitats such as oyster reefs and seagrass beds are also commonly found. San Antonio Bay comprises approximately 10 percent of all the oyster reefs along the Texas coast and 5 percent of the total seagrass coverage.
Seagrasses are most commonly found along the Matagorda Island shoreline but can also be found growing in areas of shallow water throughout the bay. Seagrasses are true flowering plants that grow rooted and completely submerged underwater. Seagrass beds create highly productive shallow water habitats and perform a variety of ecosystem functions. Their leaves and roots oxygenate the water column and sediment as well as maintain water clarity by trapping loose sediment and fine particles. Their extensive root and rhizome system reduce coastal erosion by stabilizing sediment and their leaves dampen wave energy providing added protection to the coastline. The habitat provides nursery grounds for many juvenile species such as red drum, spotted seatrout, blue crabs and shrimp as well as a direct food source for larger organisms. Sea turtles, waterfowl and manatees can all be seen consuming the seagrass blades, roots and rhizomes.
Five seagrass species can be found on the Texas coast: turtle grass, shoal grass, manatee grass, star grass and widgeon grass. Although five species of seagrass occur along the Texas coast, distribution and species composition varies along the coast as a result of freshwater inflow, salinity, depth and water clarity. San Antonio Bay is comprised mostly of Halodule wrightii (shoal grass) and Ruppia maritima (widgeon grass) most likely because both species are tolerant to wide ranges in salinity and can withstand periods of flooding and drought.
Seagrasses are an indicator species that reflect the overall health of the ecosystem. Identifying threats to seagrass habitat is crucial to managing and conserving habitat for aquatic organisms within the bay. Threats and actual loss of seagrass are attributed to both natural and human-induced processes. Natural disturbances include storms, drought and algal blooms. Human-induced disturbances include hydrological modifications, coastal development and propeller scarring. Seagrass beds are impacted by disturbances either by direct physical damage (uprooting, removal or burial) or indirect damage such as creating unfavorable conditions (decreased water quality or shading).
Propeller scarring is one of the most significant threats to seagrass. A mid- 90s study documented heavy propeller scarring along the Texas coast and spurred a statewide education and outreach campaign by the Texas Parks and Wildlife Department (TPWD) to increase awareness of the importance and value of protecting seagrass. This campaign has since grown to include proper boating practices to avoid damaging seagrass beds, habitat assessments, field sampling coast wide, and implementation of a new state regulation. As of September 1, 2013, it is illegal to uproot seagrass with a boat propeller from the bay bottom anywhere in Texas coastal waters. TPWD Coastal Fisheries Division is coordinating with TPWD Law Enforcement to ensure awareness of the new regulation. Outreach and education materials include literature distribution to local boat dealers and bait shops, billboards and social media. New signs located at your local boat ramp offer general information about the protection of seagrass and encourage good boating practices. Boaters are encouraged to avoid seagrass beds along the coast by remembering to LIFT, DRIFT, POLE OR TROLL: LIFT motors when in shallow vegetated areas; DRIFT by using the wind to cross shallow flats; use of a push POLE through shallow areas; or TROLL with a trolling motor in shallow fishing areas.
