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2 2022

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The Variability of Surface Chlorophyll-a in Lake Rawa Pening within Five-Month Observations

Amelia Karla, Nuringtyas Satria Bagus, Setiawan Riza Yuliratno, Setyobudi Eko, Adharini Ratih Ida, Aryudiawan Candra, Maslukah Lilik

Ecological Engineering & Environmental Technology

2022

Vol. 23, iss. 4

173--178

Lake Rawa Pening is a natural lake in the Semarang Regency of Central Java Province, Indonesia, and its existence is pivotal to the surrounding communities as it provides ecological, economic, and social benefits. The ecosystem health of Rawa Pening can be represented by chlorophyll-a concentration because it indicates phytoplankton biomass, nutrient availability, and fish resources. Hence, the present study aims to disentangle the monthly variability of surface chlorophyll-a in Rawa Pening Lake by analyzing water samples that were collected once a month from nine stations within five-month observations (September 2020 to January 2021). The samples were analyzed using spectrophotometric method. Results showed that the highest surface chlorophyll-a concentration (23.33 mg/m3) took place in December, while the lowest concentration (12.64 mg/m3) occurred in October. The monthly variability of surface chlorophyll-a was likely controlled by variation of rainfall, with the highest (18.72 mm) and the lowest (12.33 mm) rainfall happened in December and October, respectively. The present study also indicates the anthropogenic activities such as agricultural activities, floating food stands, aquaculture, and tourist boats may contribute to surface chlorophyll-a variability in Rawa Pening Lake.

Reducing Nitrate and Phosphate Concentrations in Shrimp Wastewater Aquaculture Using Gelidium corneum

Indraswari Nabila, Adharini Ratih Ida

Ecological Engineering & Environmental Technology

2022

Vol. 23, iss. 5

137--144

Shrimp culture wastewater contains residual feed and shrimp metabolism. Shrimp wastewater if not managed properly will be harmful to the long term viability of the farming itself and threatens environmental sustainability. This study aims to determine the potential and effectiveness of Gelidium corneum with different densities as a biofilter for vaname shrimp culture waste. This study used a completely randomized design method consisting of 3 treatments and 3 replications using different density treatments, namely T1 (1 gL-1); T2 (2 gL-1); and T3 (3 gL-1) in an aquarium volume of 30 L. The parameters observed included the concentration of nitrate, phosphate, temperature, TDS, TSS, salinity, DO, pH. Absorption effectiveness and growth of G. corneum were measured at the beginning and end of the study. G. corneum is able to reduce the concentration of phosphate in water is higher than lowering the content of nitrate. G. corneum with a density of 1 gL-1 showed the best performance in absorbing nitrate by 8% on day 15. While the 2 gL-1 treatment was able to reduce the phosphate concentration by 92% in 25 days. Absorption of Total Nitrogen content in the thallus obtained in the treatment of 2 gL-1 was 32% and total phosphate was 58% for 25 days. Therefore G. corneum can be used as a candidate for commodity in Integrated Multi Trophic Aquaculture (IMTA).