Lala I.P. Ray


TEMPORAL VARIATION OF WATER QUALITY PARAMETERS IN INTENSIVELY IMC CULTURED LINED POND

Lala I.P. Ray, P.K.Panigrahi, B. C. Mal

Abstract
Water is a crux in the life of all biological species. Aquaculture, which depends predominantly on water, regular monitoring water quality is given the most importance. An attempt was made at Indian Institute of Technology, Kharagpur, West Bengal, India during 2006-07 to study the response of the growth of Indian Major Carps (IMC) semi intensively cultured in polythene lined ponds. Nine ponds were stocked with IMC at stocking densities of 2.0, 3.5 and 5.0 numbers per square meter. The pond water quality was measured at regular interval to determine the levels of NO3, NO2, NH3 and PO4 pollution. Physio-chemical parameters such as temperature, pH, dissolved oxygen, organic carbon were also monitored along with the above critical nutrients. The average water temperature, dissolved oxygen, and pH during culture period were 15–32.5°C, 6.7–8.6 ppm, 3.1–7.8 ppm and 6.5–8.0 respectively. Nutrients like Total Ammonium Nitrogen (TAN), Nitrate-N, Nitrite-N and orthophosphate-P ranged between 0.2 to 1.2 ppm, 0.1-0.7 ppm, 0.02-0.1 ppm and 0.05-0.4 ppm respectively. Water exchange interval varied between 30 to 42 days for different stocking densities. Nutrient concentration initially increased with time until the water was exchanged. The exchange of water from the pond was carried out before nutrient concentrations reached the critical values. The fluctuation of nutrients in the pond water with higher stocking density (STD-3.5 and 5.0) was higher as compared to the lower stocking density (STD-2.0). The biomass increases with the increase stocking density but water exchange is needed. In this paper an attempt has been made to highlight the variation of important water quality parameters during a perennial culture period and its management by water exchange.

Key words: Water quality, IMC, stocking densities, water exchange

VARIATIA TEMPORALA A CALITATII APEI LA CRAPUL INDIAN CRESCUT ÎN CULTURA INTENSIVA, ÎN BAZINE ARTIFICIALE

Lala I.P. Ray, P.K.Panigrahi, B. C. Mal

Abstract
Apa este un element esential in viata tuturor speciilor biologice. În acvacultura, monitorizarea periodica a calitatii apei are o importanta cruciala. O astfel de preocupare a fost în atentia celor de la Institutul Indian pentru Tehnologie din Kharagpur, West Bengal, India, pe parcursul anilor 2006-2007. Acestia au studiat raspunsul productiv al crapului indian la cultura de tip semiintensiv, desfasurata în bazine artificiale cu pereti din material polietilenic. Noua bazine de acest tip au fost populate cu crap indian, la densitati de 2,0, 3,5 si 5,0 exemplare/m2. Calitatea apei a fost masurata la intervale regulate de timp, pentru a determina gradul de poluare cu NO3, NO2, NH3 si PO4. Câtiva parametri fizico-chimici, ca de exemplu temperatura, valoarea pH, oxigenul solvit, carbonul organic, au fost de asemenea monitorizati în paralel cu nutrientii critici, enuntati anterior. Temperatura media a apei, oxigenul solvit, carbonul organic si valoarea pH au fost de 15–32.5 °C, 6.7–8.6 ppm, 3.1–7.8 ppm si respectiv 6.5–8.0. Unii nutrienti, precum Azotul Amoniacal Total (AAT), Nitratii-N, Nitritii-N si ortofosfatul-P au variat între 0.2-1.2 ppm, 0.1-0.7 ppm, 0.02-0.1 ppm si respectiv 0.05-0.4 ppm. Intervalul de înlocuire al apei a variat între 30 si 42 zile, în functie de densitatea la populare. Initial, concentratia nutrientilor a crescut progresiv, pâna în momentul înlocuirii apei. Aceasta a fost schimbata din fiecare bazin, înainte ca nutrientii sa atinga valori critice ale concentratiei. Fluctuatia nutrientilor a fost mai mare în bazinele cu densitati la populare mai ridicate (3,5 si 5,0 exemplare/m2) comparativ cu bazinul care a avut cea mai redusa densitate initiala (2,0 exemplare/m2). Prin urmare, biomasa s-a dezvoltat mai bine în bazinele cu densitate mai mare la populare, dar aceasta situatie a impus mai devreme schimbarea apei din bazin.

Cuvinte cheie: calitatea apei, crap indian, densitati la populare, schimbul apei