A research on improving the pond systems of earthen pond aquaculture enterprises produces marine fish

Making projects for solving the problems of sector, produces marine fish in earthen ponds that in business in Milas County of Muğla Province, is very important for the sustainability of earthen pond enterprises. Improving pond systems of earthen pond enterprises that produces marine fish and removing the knowledge lacks about the water quality changes in ponds were aimed in that study. Three of erarthen ponds in an earthen pond enterprise in Savran (Milas), were used within the study. Used ponds were coded as control (K), bottom discharged (T) and bottom discharged and aerated (TH). A currently used pond in enterpsises were used as control pond. A bottom discharge system were applied to bottom discharged pond (T). A bottom discharge system and aerating system, that takes water from the pond and draining again to the pond after aerating, were applied to bottom discharged and aerated pond (TH). During a production cycle (11 months) physico-chemical parameters were in situ measured from pond inflow water, outflow water and determinated points in ponds. Moreover night measures were conducted six times from March 2019 to August 2019, when the temperature increases, for screening the daytime-night differencies in physico-chemical parameters. Nitrogen compounds (nitrite, nitrate, ammonium, ammonia), total phosphorus, chlorophyll-a, chemical oxygen demand and total suspended solids amounts were monitored monthly. In addition, for monitoring the changing in organic-inorganic matter content quarterly and for monitoring the changing in element amounts semi annually, sediment samples were taken and analysed. The average water temperature of inflow water were measured as 18.65±0.58 °C during the production period. During the study, the lowest temperature was measured as approximately 9 °C and the highest temperature was measured as approximately 27 °C. The highest dissolved oxygen value was measured as 9.11±0.10 mg/L at the surface of the TH pond in December and the lowest dissolved oxygen value was measured as 3.14±0.27 mg/L at the bottom of control pond in May. Amonia values in water samples were found for K, T and TH ponds averagely as 0,358±0,208; 0,433±0,200; 0,453±0,197 mg/L respectively. Amonium values in water samples were recorded for K, T and TH ponds averagely as 0,685±0,624; 0,624±0,335; 0,593±0,178 mg/L respectively. Nitrite values in water samples were determined for K, T and TH ponds averagely as 0,202±0,191; 0,220±0,181; 0,221±0,175 mg/L respectively. Nitrate values in water samples were recorded for K, T and TH ponds averagely as 0,661±0,155; 0,731±0,227; 0,756±0,231 mg/L respectively. Total phosphorus values in water samples were determined for K, T and TH ponds averagely as 0,121±0,155; 0,168±0,265; 0,220±0,251 mg/L respectively. The total nitrogen amount of sampled sediments from K, T ve TH ponds were determined as 1457±133, 1620±776, 1430±459 mg/kg at the beginning of study and 2847±827, 2797±1116, 2257±165 mg/kg at the end of the study respectively. Also the total phosphorus amount of sampled sediments from K, T ve TH ponds were found as 602±124, 546±49, 558±446 mg/kg at the beginning of study and 1332±96, 1107±83, 1156±230 mg/kg at the end of the study respectively. The aerator system designed with the purpose of increasing disolved oxygen level in pond water and increasing the water current in pond, had increased the dissolved oxygen level of treatment water passes from the system averagely 16.85%. While the organic and inorganic matter content of the waste obtained from outflow water of pond via settling were analysed, the organic matter content was seen as 16.37% in February and 22.47% in August. At the end of study, new bottom discharge system was found more successful than the traditional discharge system used in control pond. The organic matter discharged through the discharge systems used in K, T, TH ponds was determined as the value of 105.4%; 136.1% and 133.1% of the organic matter content of pond waters respectively. In discharging organic matter accumulated in the pond bottom; the new system was about 7 times more effective than the traditional discharge system. As a conclusion, with the use of newly developed bottom discharge system, organic material sinks to the bottom and accumulates during the production period, can be removed significantly. The data produced within the scope of the study will contribute positively to the sustainability of the earthen pond enterprises.