The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium


SOIL NITRIFYING ENRICHMENTS AS BIOFILTER STARTERS IN
INTENSIVE RECIRCULATING SALINE WATER AQUACULTURE


Amit Gross 1*, Anna Nemirovsky 1, Dina Zilberg 2, Anna Khaimov 1, Asher Brenner 3, Eviatar Snir 4, Zeev Ronen 1 and Ali Nejidat 1

1 Department of Environmental Hydrology and Microbiology, Jacob Blaustein Institute for Desert Research, Ben Gurion University of the Negev, 84990 Israel

2 Department of Dry Land Biotechnologies, Jacob Blaustein Institute for Desert Research, Ben Gurion University of the Negev, 84990 Israel

3 Department of Environmental Engineering, Ben Gurion University of the Negev, 84990 Israel

4 Negev Shrimps Ltd.(Matan), D.N.Haluza, Ramat Negev, 85515 Israel


Abstract

Intensive recirculating aquaculture relies on biofilters to maintain satisfactory water quality in the ponds. Without a start-up, establishment of new biofilters in aquaculture ponds requires a long time, causing significant losses and environmental harm from the discharge of nitrogen-rich effluents. A laboratory scale setup (7 l aquaria stocked with shrimp and fish) demonstrated that an external start-up nitrifying enrichment culture performed similarly to the natural bacterial population of an established pond biofilter, and better than similar biofilters without the start-up culture (control). The ammonia concentration in the control treatment increased daily and reached 18 mg/l during a 14-day experiment whereas in the treated aquaria it averaged less than 2 mg/l.

Fish growth and survival were similar in the established pond and the start-up treatments (average growth 0.45 g/14 days; 95% survival) and significantly higher than in the control (average growth 0.0 g/14 days; 80% survival). The source of the enrichment cultures was soil samples collected from the region where the farm is located. This approach may lead to the development of bacterial amendments (probiotic products) that can be used as start-up cultures for new operations or damaged filters, and potentially enhance nitrification in established filters. Since the cultures are collected from soil, it is unlikely that they will be contaminated with agents that cause diseases in fish. This will improve water quality and, consequently, aquatic animal production.

*email: agross@bgumail.bgu.ac.il

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