Ukuhlolwa Kwekhwalithi Yamanzi Wokufuya iimfesi

© Marinda Louw
Ikhwalithi yamanzi wedamu newomlambo lapho avela khona asetjenziselwa ukufuya iimfesi ngehlelo lokusebenzisa amanzi afretjhi ebizwa nge-freshwater fish farming kufanele ahlolwe ngaphambi kobana kuthome ukufuya iimfesi. Ngasosoke isikhathi thatha amasampula wamanzi kusukela eendaweni ezahlakahlukeneno edamini ungathathi wemaqadi kwedamu kwaphela.

Ngaphezulu kwamanzi: hlola amasampula wamanzi uhlole umoya wokuphefumula (oxygen), pH, inayithrojini (nitrogen) epheleleko, i-amoniya (ammonia), ne-phosphorus (P).
Emanzini athethwe ngaphasi kwedamu: hlola umoya wokuphefumula (oxygen), pH, ne-amoniya (ammonia).

Asampuliwa njani Amanzi Wedamu

Isikhathi esihle sokuthatha amanzi wokusampuliwa esifundeni se-Western Cape yinyanga kaSinyikhaba kufikela kuTjhirhweni, kutjho uHenk Stander onguhlokokulu wamatheknini e-Aquaculture: Department of Animal Sciences at Stellenbosch University.
Sampula amanzi angaphezulu (kusukela ku 1 kuya ku 2 m ukutjhingela phasi) neduze nangaphasi kwedamu ngokusebenzisa isampula yamanzi. Emadamini angatjhingeli khulu, thatha isampula yamanzi ephakathi nendawo yedamu enye uyithathe emaqadi.
Thatha isampula yinye nofana amabili nofana amanengana nakuvuma imali; ukuhlolisisa kuhle elabholatri kuthatha imali engalingana ne R1 500 ne R2 000 (2019). Isampula yesilinganiso esingaba yi 350 ml singanela. Bulunga amanzi ngesiqandisi bese uyawahlahluka nofana uwahlolisise emalangeni amathathu wokuthatha isampula, kuyelelisa uStander.

Izinga Lekhwalithi Yamanzi Afanele Ukufuya iimfesi

©Brian Ginn, North American Lake Management Society (NALMS)
Amasampula wamanzi ahlolelwa izinto ezinengi ezahlukahlukeneko kufaka hlangana ukuhlolelwa amakhemakhali abizwa ngama-heavy metals. Ikhwalithi yamanzi ngaphambi kobana kuthome ukwenziwa ihlelo le-freshwater fish farming kufanele ibe ngendlela elandelako:

Umoya wokuphefumula (Oxygen):
Umoya owaneleko ngaphasi kwamanzi: 7 ukuya ku 12 mg/L.
Izinga eliphezulu lesilinganiso somoya litjengisa ukukhula okunengi kwe-phytoplankton begodu nobungozi obungezelelweko bomoya ophumako lokha i-phytoplankton nayifako.
pH:
Amanzi wangaphezulu i-pH yayo kufanele ibengaphasi kwaka 8 nahlangana ko 5 no 8. Umehluko we-pH hlangana namanzi wangaphezulu nangaphasi ubengaphasi ko 1.5.

Amoniya (Ammonia):
Amazinga we-amoniya (ammonia) ngaphasi kufanele angadluli i-1 mg/L.

TP:
Amazinga apheleleko we-phosphorus (TP) wamanzi wangaphasi kufanele angadluli 50 μg/L (0.05 mg/L).

TN:TP
Iretjhiyo epheleleko yenayithrojini (nitrogen): i-phosphorus epheleleko (TN:TP) ingadluli ku 20. Lokhu kwenzelwe ukubalekela inambitho elingasimnandi efesini elenziwa bulwembu obungakahlwengeki.

Visibility Ukubonakala
Ukubonakala kuhle kufanele kubonakale kufikela ku 50 cm okutholakala ngokufunda i-Secchi-disc.

Translated by Busisiwe Skhosana