Note: This item is more than 10 years old. Please take the publication date into consideration for any date references.

PrintPlain TextPermalink

News Release
Media Contact:
TPWD News,, 512-389-8030

April 15, 2008

Biologists Launch Study of Two Texas Tidal Streams

AUSTIN, Texas — In March, Texas Parks and Wildlife Department biologists began a two-year study of two tidal streams on the middle coast, sampling fish, bottom-dwelling organisms, and water quality to measure the quality of aquatic life inhabiting these ecologically important areas.

Tidal streams are areas where saltwater from bays mix with freshwater coming down from rivers. They are components of estuaries, a better-known term for areas where freshwater and saltwater converge. Because tidal streams provide a special kind of habitat, they are vital nursery grounds for many types of fish and shellfish, including economically important species like shrimp and game fish.

"Tidal streams are complex ecosystems," said Janet Nelson, a TPWD coastal biologist. "We need to know more about threats to them that could undermine biodiversity in general and our sport and commercial fisheries in particular. There hasn’t been enough study of tidal streams to completely understand what drives changes in these systems."

Nelson said tidal stream salinity varies seasonally with rainfall, and this drives changes in fish populations. Other factors that affect habitat and water quality include hydrology (water movement), freshwater inflow, subsidence, land use in the watershed and wastewater discharges.

The Texas Commission on Environmental Quality has contracted with TPWD to study two tidal streams, the tidal portions of Aransas and Mission rivers connected to Aransas Bay. Field sampling began in late March and will continue until November 2009. Sampling will occur every six weeks during the spring, summer and fall seasons. Water and sediment (bottom) samples will be collected for laboratory analysis. Other parameters that will be measured include dissolved oxygen, pH, temperature salinity, and stream flow.

Fish, shrimp, crabs and other swimming organisms will be collected, identified and measured. Sediment from the bottom of the streams will be collected to see what types of organisms live there. A detailed field study will be done of habitat within the stream and on the banks. Also, a GIS land cover analysis will be done to see how the land surrounding the stream is being used.

When the fieldwork is completed, the final report to is due to TCEQ in 2010. This gives TPWD scientists about one year to analyze and interpret all the data and write a report on the ecological health of each stream.

AR 2008-04-15

More Information:

Publication — Permission is granted to publish, in whole or in part, any news releases on this page.

Print — A print-friendly version of the news release shows only the release with font sizes set to the browser default.

Plain Text — Plain text versions of TPWD news releases are provided for copying and pasting into editing software.

To copy text into an editing software:

  • Click a Plain Text link to display the plain text page in your browser.
  • Select all.
  • Copy.
  • Paste in a document in your editing program.

Permalink — This is a direct link to the news release, omitting the navigation context from the URI.

English/Spanish — News releases posted in both English and Spanish have one of these links.

If you have any suggestions for improving these pages, send an e-mail to and mention Plain Text Pages.

(5.4.16 i)