Phosphorus Loading from Fish Farming Activities to Wadaslintang Reservoir Waters

Abstract

Wadaslintang Reservoir located in Wonosobo Regency of Central Java provides to fish farming area using floating net cage. There are 2 feeding system applied that are semi intensively system managed by local community and super intensively managed by PT. Aquafarm. Both different feeding systems resulted in the amount of pollutant load coming into the reservoirs in the form of total P derived from the remaining feed and feces of fish entering into the reservoir. This can trigger the eutrophication condition of the reservoir waters. The purposes of this study were 1) to calculate the capacity of Wadaslintang reservoir to phosphorus load based on its morphometry and hydrology, 2) to evaluate the capacity of wadaslintang reservoir to Phosphorus load from floating net cage activities in wadaslintang reservoir, and 3) to design the program on the reducing load of Total Phosphorus from floating net activities in wadaslintang reservoir. The research was conducted by survey method in the Wadaslintang Reservoir during January 2016 in both locations of floating net cage fish farming. Parameters measured were P content in fish and P content of feed used in both cultivation systems, and P concentration of reservoir water. The amount of pollutant load coming into the reservoir and its impact on the P concentration of water was calculated using the formula. The results showed that Wadaslintang Reservoir to phosphorus load capacity was 106,56 ton P/year. The Phosphorus load from floating net cage was 216,2 ton P/year. The P load from PT. Aquafarm have exceeded the capacity as much as 70,74 ton P/year. In general the existence of fish farming system using floating net cage in Wadaslintang Reservoir has contributed to increase the concentration of P equal to 43,9% or in other words as much as 50% of P load that goes into reservoir of wadaslintang. Programs designed to reduce the phosphorus load could be done by reducing the number of floating net and decreasing all the activities in the catchment area up to 50% to fulfill phosphorus standard of 100 mg/m3.

Journal of Water and Land Development

“…The unpolluted condition was caused by extensive water discharge, which led to pollutant dilution. In the floating net area managed by the local community, the level of pollution was lower than in the area of the PT Aquafarm floating nets; waste production from the community net area (39.2 t•y -1 ) was less than the waste production from the PT Aquafarm facility (177.3 t•y -1 ) [PIRANTI et al 2018b].…”

“…This condition is presumably caused by fish feed residue and fish droppings that fall to the bottom of the reservoir, carrying high phosphorus that drives increases in certain types of phytoplankton able to tolerate high-phosphorus conditions. Based on the findings by PIRANTI et al [2018b], the phosphorus load from floating net cages has exceeded approximately 50% of the reservoir's capacity.…”

“…Based on monitoring of water quality using physicochemical parameters that have been previously reported [PIRANTI et al 2019], the water quality status of Wadaslintang Reservoir was heavily polluted during the dry season, whereas it was moderately polluted during the wet season. The number of parameters that were above the standard was greater in the dry season (10 parameters) than in the wet season (3 parameters) -Table 5.…”

Short Communication: Comparison of the water environment aspects and production of Nile tilapia (Oreochromis niloticus) between biofloc and conventional aquaculture systems in tropical dryland region

“…In addition, the presence of phosphate in the waters is related to stocking density, residual feces, and food residue that fish do not eat. Therefore, phosphate values in aquaculture systems occur in line with an increase in fish density, metabolic waste, and feed waste that fish do not eat (Kunindar et al 2018;Piranti et al 2018). However, both in conventional and biofloc aquaculture, the phosphate values in this study were still below the phosphate quality standard, which was <2 mg/L (Effendi 2016;Putri et al 2019).…”

Water quality assessment based on microbiological parameter indicators for drinking water criteria on the Wadaslintang Reservoir

“…Given the large role of these water resources, good management is needed. Some previous studies show Wadaslintang Reservoir is polluted [3]. One indicator of pollution can be known based on microbiological indicators, because water is a natural habitat of microorganisms [4].…”