Poultry manure fertilization of Egyptian aquaculture ponds brings more cons than pros

• Aquaculture is a crucial sector for Egyptian food production, providing a cheap source of animal protein while securing income and employment for a substantial part Egypt’s population. Nile tilapia (Oreochromis niloticus) is the most commonly produced fish, usually farmed in earthen ponds in the Nile River delta. A common practice among farms is to fertilize ponds with chicken manure (CM) in order to increase nutrient levels and promote phytoplankton, consumed by the fish. However, with reports of use of antibiotics in Egypt’s poultry sector, and that CM contains residues of antibiotics, antibiotic resistant pathogens and antibiotic resistance genes (ARGs) are production benefits large enough to compensate a potential health hazard?Using production data from 499 aquaculture farms and fish pond sediment from 28 ponds we evaluated potential benefits in yields and profitability for farms using CM for fertilization, and used qPCRs to screen sediments for three antibiotic resistance genes coding for resistance to the most commonly used antibiotics in the poultry sector. The analysis shows no significant benefits to fish yields or profitability in farms where CM is applied, but significantly increased nutrient loads. Meanwhile, we detect increased abundances of tetA and tetW resistance genes in fish pond sediment where CM is applied. With eutrophication of local waterways at risk, and dissemination of ARGs, we recommend Egyptian tilapia pond farmers to refrain from using CM fertilization for the purpose of increasing fish yields.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Fisk- och akvakulturforskning (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Fish and Aquacultural Science (hsv//eng)

Nyckelord

Aquaculture

Chicken manure

Eutrophication

ARGs

Profitability

Ecotoxicology

ekotoxikologi

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