2008 Monitoring Update: Water Quality, Water Temperatures, and Clam Health

Water Quality Monitoring:

A partnership developed by the Shellfish Aquaculture Extension Program (SAEP) with federal and state agriculture agencies allowed for operation and maintenance of water quality and weather monitoring stations, which serve as a decision support tool for the clam industry. Stations were located at five high-density lease areas in four coastal counties (Dixie, Franklin, Indian River and Levy). These stations provided timely information to clam growers, allowing them to make informed management decisions based on temperature, salinity and other measurements. Continuous data and monthly archived data can be found at the UF/IFAS Shellfish Aquaculture Extension’s website http://shellfish.ifas.ufl.edu.

Water Temperature Monitoring:

Water temperature plays an important role in biology and directly affects the bodily functions of aquatic organisms necessary for growth and survival. It also influences water quality parameters, such as dissolved oxygen and pH. An ongoing monitoring project is providing detailed and broad coverage of water temperatures by deploying inexpensive data loggers at multiple clam aquaculture leases to adequately describe variability possibly due to water depth, substrate characteristics, currents, and other parameters. The waterproof data loggers used for this project (pictured at right) are small, allowing them to be placed either inside of or attached to the outside of a clam bag on the lease site. In May 2008, 39 data loggers were deployed in the Cedar Key area providing 10% coverage of the Gulf Jackson and Pelican Reef lease areas and 25% coverage of the Dog Island and Corrigans Reef lease areas. Water temperature trends were different from those observed the previous year. In 2008, water temperatures were not as high with peak temperatures recorded in July and maximum values of 92.9oF reached on July 11. At that same time, temperatures ranged from 88.6oF to 92.7oF at the other lease sites. Water temperatures on the Gulf Jackson leases reached 88°F for 11 to 17 days during July 2008, while 90°F was exceeded on 1 to 10 of those days. Alternately, water temperatures on the Corrigan’s Reef leases reached 88°F for 14 to 15 days during the same month, while 90°F was exceeded on 4 to 6 of those days. These values are important to clam production as clams cease growth processes at approximately 88°F and stop filtering around 90°F.

Clam Health Monitoring:

Baseline health monitoring of cultured aquatic stocks has proven to be an important management tool. The UF Fisheries and Aquatic Sciences (FAS) Diagnostic Lab offered basic water quality parameter analysis; bacterial culture of water, algal stocks, and clam larvae; and histologic examination of clam larvae and adults (all for a modest fee). As soon as mortalities are observed, a sample of animals should be collected and submitted for analysis. Any delay makes disease identification more difficult. The FAS lab can provide specimen jars that contain chemical fixatives, and culture media.

Conducted by:

• Leslie Sturmer, University of Florida IFAS, Shellfish Aquaculture Extension

• B. Denise Petty, University of Florida IFAS, Fisheries and Aquatic Sciences

Funding:

USDA Hatch

2008 Monitoring Update: Water Quality, Water Temperatures, and Clam Health (pdf file)