Water Quality Monitoring of Texas Offshore Artificial Reefs

Artificial reefs provide a habitat for marine organisms and abundant ecosystem services. In reef ecosystems, several organisms tolerate a small range of physical water properties and any change in water quality could affect their survival. Therefore, monitoring how these artificial reefs respond to environmental changes due to natural and anthropogenic causes is essential for management.

 The U.S. Geological Survey (USGS) and the Texas Parks and Wildlife Department (TPWD-ARP) are collaboratively monitoring artificial reefs located in the Gulf of Mexico in order to understand the productivity of these ecosystems, and their response to environmental changes. To accomplish this, TPWD use established protocols for biological monitoring, and the USGS collects physical and chemical water quality data.

The selected artificial reef sites are located nearby national marine sanctuaries to facilitate comparison to natural reefs, but also provide enough spatial variability for comparison purposes. Additionally, the sites differ in artificial reef foundation providing an opportunity to evaluate variability in reefing structure.

Physical water quality parameter profiles are collected to: (1)document variability of water quality between sites, (2)characterize the environmental conditions at the artificial reefs, and (3)monitor the reefs for potential impacts from anthropogenic stresses. Monitors have also been deployed at selected locations between trips to obtain a continuous record of physical water quality parameters. Water quality samples for nutrients, chlorophyll a, Pheophytin a, and an assortment of metal analytes are collected by USGS divers at the top of each artificial reef structure.

Collecting long-term monitoring data with targeted sampling for constituents of concern at artificial reefs may provide a foundation to determine their current status and establish trends that can be used for future management. A record of hydrographic variables could be used to explain and understand potential community structure changes as determined by biological monitoring protocols and provide information on optimal environmental conditions for locations of future artificial reef locations.

Techniques, methods and preliminary results of these water quality monitoring efforts will be discussed.