Mati yakahle ya khwalithi ya hlohletela kukula kahle ka tihlampfi (good quality water = faster growth), ku humelela ka mavabyi xikan’we na nantswo na muhlovo wa hlampfi. Khwalithi ya mati yivangiwa hileswi landzelaka:
Mahiselo ya mati
Levele ya moya ematini
Level ya Ammonia ematini
pH ya mati (the level of acidity or alkalinity)
Swiphiqo swotala swa khwalithi ya mati eka vufuwi bya tihlampfi swivangiwa hiku hela ka moya ematini, levele yale henhla ya ammonia kumbe levele yale henhla ya pH. Swiphiqo leswi swina vuxaka swinene na levele ya microscopic algae (nkuxu) e matini.
Kukula ka nkuxu lowu swiya hi nhlayo ya swakudya - nitrogen (N) na phosphorus (P) - ematini. Swakudya leswi swinghena e dan’wini hikokwalaho ka:
Laha mati ya humaka kona (inflow of water into the dam).
Mikhukhula leyinghenaka himinkarhi ya timpfula (runoff).
Swakudya swa tihlampfi hinkarhi lowu ti tswalanaka.
Mahiselo ya Mati eka Vufuwi bya Tihlampfi
Trout hi xitalo yikula exikarhi ka 14 na 18°C (16°C optimum water temperature) kambe tinxaka leti tsakelaka kuhisa tofana na sharptooth catfish tikula kahle eka mati lawa ya kufumelaka ya (20 - 30°C) na tilapia yitsakela mahiselo ya mati yale henhlayale xikarhi ka 24 - 34°C.Trout yi chava ngopfu mati lawa ya kufumelaka. Mahiselo lawa ya tlulaka 20°C yata vanga leswaku trout yiyima kukula naswona yata tisa swivangelo swa vuhumelerisi, kufana na khombo leri engetelekeke ra mavabyi na swiphiqo swa moya, kuhlamusela Henk Stander mininjhere nkulu wa swa vuthekiniki e Aquaculture: Department of Animal Sciences, Stellenbosch University.
Swiphiqo leswi (increased disease risk and oxygen reduction) switala kuvangiwa hi nkuxu lowu taleke e matini. Loko mahiselo ya fika eka 21°C na kuya e henhla, nhlayiso wa vukheta wa laveka kusivela rifu ra tihlampfi xikan’we naku thyakisiwa hi nkuxu. Ku thyakisiwa hinkuxu swivangiwa hiku engeteleleka ka nkuxu wa wasi na rihlaza leswi vangiwaka hiku tlakuka ka mahiselo yale henhla ya mati na kukumeka ka swakudya. Nkuxu wu humesa ti khemikali tofana na swin’wani swa misava leswi nuhaka, geosmin. Leswi switswongiwa hi hlampfi naswona swicinca nantswo wa nyama ya hlampfi.
Level ya Moya eka Vufuwi bya Tihlampfi
Swiphiqo swa moya switala ku vangiwa hi nkuxu. Nkuxu wuva na photosynthesis kutani wuhumesa moya. Hi levele yantolovelo ya nkuxu, akungevi na swiphiqo.
Loko levele ya nkuxu yitlakuka, levele ya moya namadyambu ya hunguteka yiva ehansi ka 5 mg/L naswona kutava na swiphiqo swa moya ematini mixo lowu landzelaka.
Xavumbirhi, loko nhlayo yikulu ya nkuxu yi fa swinga languteriwangi (due to cloudy weather conditions or spraying of algaecides), ti aerobic bacteria tita kula hi xihatla swinene kupfuneta ku borisa nkuxu lowunga fa. Ti aerobic bacteria leti tidya moya leswi hungutaka levele ya moya e dan’wini hiku hatlisa naswona swivangela tihlampfi ntshikelelo.
Level ya Ammonia eka Mati yo Tenga
Ammonia yiva hi xivumbeko xa phoyizeni (free ammonia) xikan’we naku pfumala phoyizeni (ionised ammonia) kambe xiyimo xa phoyizeni xitala kuva ehansi ka 10% eka nhlayo hinkwayo ya ammonia leyinga kona. Eka mati yokufumela (+20°C) lawa yangana pH (8.5) yale henhla, levele ya phoyizeni ya ammonia yita tlakuka.
Levele ya ammonia ayitali ku vanga swiphiqo eka madamu handle kaloko kuri eka ndzhawu leyinga entangiki (5 m or less) naswona hi nhlayo yale hansi ya lembe yale hansi ka yin’we. (‘Annual turnover’ is the rate at which a dam’s full water volume is replenished by rain or inflow water).
pH ya Mati ya Damu
Xin’wana xankoka swinene lexinga tlakusaka levele ya pH ikukula ka nkuxu. Kutala ka nkuxu swinga engetela levele ya pH ngopfu ngopfu eka madamu yale mapurasini lawantsongo kuya eka levele yale henhla ka pH 9 (especially in the afternoon). Leswi swivangiwa hiku susiwa ka carbon dioxide hinkarhi lowu kuhumelelaka photosynthesis. Level leyi yale henhla ya pH yita veka tihlampfi ehansi ka ntshikelelo.
Ku tlakusa/antswisa ti levele leti, ku cinciwa ka mati swa laveka, ku cheriwa mati yantshwa loko swikoteka. Kumbe unga chela barley straw.Translated by Ike Ngobeni