69    CHARACTERIZATION AND SIGNIFICANCE OF
INDICATOR BACTERIA IN COMMERCIAL
AQUACULTURE PRODUCTION FACILITIES
R.J. Fiederlein, Graduate Research Assistant
University of Texas School of Public Health
Environmental Health Specialist
Galveston County Health District
E.M. Davis, Professor
Environmental Sciences
University of Texas School of Public Health
J.J. Mathewson, Assistant Professor
Center for Infectious Diseases
University of Texas School of Public Health
Houston, Texas 77225
INTRODUCTION
The aquaculture industry in the United States has grown in parallel with the increase in
seafood consumption over the past 10-15 years. Projections suggest that aquaculture will supply
up to 25% of all domestically consumed seafood by the end of the century.1 Catfish production is
the single largest segment of the domestic aquaculture industry. In 1993 alone, approximately
1,500 catfish operations in the U.S. utilized 150,000 surface acres to produce 500 million pounds
of catfish.2
Waste discharges from aquaculture operations are regulated at both the federal and state level.
The federal government regulates surface water discharges from aquaculture facilities using regulations promulgated under the Clean Water Act. These regulations (40CFR Part 122. Subpart B,
Sec 122.24, and Subpart D, App C) designate concentrated aquatic animal production facilities
as point sources of pollution, thus subjecting them to National Pollution Discharge Elimination
Systems (NPDES) permit requirements. To date, the EPA has not issued guidelines regarding
surface water discharges from aquaculture facilities and permits are addressed on a case-by-case
basis.3 At the state level, regulatory actions have increased in recent years. Texas environmental
authorities have issued a small number of permits for aquaculture and mariculture operations and
Florida environmental authorities have developed a general permit for fish farms.4
Previous studies of aquaculture effluents have primarily characterized the organic, chemical,
and physical components of discharged wastewater and have only characterized to a limited extent the microbial component of discharged wastewater.4~* This study was initiated to examine
the levels of four wastewater indicator bacteria groups and to examine to the genus level the
members of one of these groups in wastewater, or potential wastewater, from aquaculture facilities over the course of the growout season of several different species of fish. This study also examined the relationships between these bacterial levels and other water quality parameters and
operational variables and enumerated and characterized Aeromonas hydrophila complex bacteria,
members of which are potential water-borne pathogens. The effectiveness of waste stabilization
ponds in the treatment of aquaculture wastewaters was also evaluated.
Samples were analyzed from each of the two primary aquaculture production techniques utilized in southeastern Texas. Water at several locations throughout a modified raceway system
was analyzed and the water in earthen, static ponds was analyzed to characterize it as a potential
effluent if it were to be discharged, as is often done to facilitate harvest, improve water quality,
or to recondition ponds.
50th Purdue Industrial Waste Conference Proceedings, 1995, Ann Arbor Press. Inc.. Chelsea. Michigan 48118.
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