Water Quality Monitoring at Offshore Artificial Reefs

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USGS Texas Water Science Center scientists are collecting physical and chemical water properties at selected Texas artificial reefs to provide the initial foundation to establish the status and long-term trends in the environment and information essential for sound management decisions and long-term planning.

Artificial reefs are structures placed by humans in the aquatic environment, which alter the habitat to achieve ecosystem benefits. The Texas Artificial Reef Program (ARP) in the Gulf of Mexico is managed by the Texas Parks and Wildlife Department (TPWD).  To date the Texas Artificial Reef Program in Texas has 66 permitted reef sites, including 35 placed in the General Permit Area found in High Island. TPWD has been developing protocols for the ARP biological monitoring. However, the understanding of how water quality and environmental characteristics impact the biological communities found on the TPWD reef sites has not been included in past research plans.

Continued coastal activity and inter-annual climate variability can alter ecosystem diversity and add a complexity of environmental stresses. Understanding how a reef ecosystem responds to changes such as climate change, ocean acidification, harmful algal blooms, ocean current shifts, spawning, migration, and other marine phenomena is essential for managers and researchers. Many biotic species survive only within small ranges of physical water properties. Any significant change in physical or chemical water quality could therefore affect the growth and survival of reef organisms. 

USGS Texas Water Science Center divers collecting water-quality samples at an artificial reef

USGS Texas Water Science Center divers collecting water-quality samples at an artificial reef. (Public domain.)

The USGS Texas Water Science Center has the capabilities to bring in-depth hydrologic data into the TPWD ARP which will provide insight into the characteristics of the water surrounding the artificial reef sites. Collecting long-term monitoring data and targeted sampling for constituents of interest at these sites will provide the initial foundation to establish the status and long-term trends in the environment and information essential for sound management decisions and long-term planning. Additionally, it could provide:

  • An understanding and record of changes in hydrographic variables to correlate to the current biological monitoring protocols in order to determine if there is a change in species structure with slight variations in environmental characteristics.
     
  • A better understanding of optimal environmental conditions for locations of future artificial reef locationsA record for understanding artificial reef response to changes in environmental conditions.
     
  • A basis of comparison to the nearby National Marine Sanctuaries.
USGS Texas Water Science Center divers collecting water-quality samples at an artificial reef.

USGS Texas Water Science Center divers collecting water-quality samples at an artificial reef. (Public domain.)

Data-collection sites were chosen to compare differences in artificial reef environments and variability in reefing structures. Sites include a partial removal rig, a toppled rig, and a standing rig with future plans to be converted to a partial removal site. Sites are located in different proximities to national marine sanctuaries.     

Physical water-quality parameters to be measured are

  • water temperature,
  • specific conductance and salinity,
  • pH,
  • dissolved oxygen concentration,
  • turbidity,
  • chlorophyll,
  • blue-green algae, and
  • light intensity. 

These parameters can characterize the natural environmental conditions at the artificial reef sites as well as monitor the reefs for potential impacts from anthropogenic stresses.

Nutrient and metal concentrations will also be analyzed. When nutrient levels increase it can promote the rapid growth of algae, bacteria, and other organisms harmful to reef systems. Metal concentrations can be a potential indicator for monitoring ocean acidification, and can also damage organisms on a cellular level.