Increment of industrial development and energy demands for transportation and electricity have increased diesel-fuel uses to fulfil global energy needs. Carbon emission as impact of high fossil diesel use which pollutes the air gradually increases green house gases (GHG) and increases the intensity of acid rains. Furthermore, scarcity of fossil-fuels resources has caused high price of diesel-fuel which in turn to have increased the prices of all commodities. Nostoc muscorum is filamentous Cyanobacteria species which lives both terrestrial and freshwater aquatic environment. This strain has good ability in producing high biomass and potential in producing lipid. In where, Nostoc muscorum has potential as biodiesel feedstock alternative of food-plants sources. This study was conducting to evaluate the potential of Nostoc muscorum cultured in BG-II medium as biodiesel feedstock source. Evaluation of the nutrient requirement of Nostoc muscorum cultured in BG-II medium was done through assimilation of nitrate (NaNO3)-phosphate (K2HPO4). Biomass production as growth parameter was measured by weighing the dried biomass for 14 days of culture. Daily lipid production was evaluated by lipid extraction using Soxhlet method. The result showed that Nostoc muscorum cultured in BG-II medium required 644.6795 mg/L of NO3 -and 25.1566 mg/L of HPO4 -with the highest biomass production 0.21 grams/300 mL. Furthermore, Nostoc muscorum as multicellular Cyanobacteria could grow well in BG-II medium at SGR 0.0964 µ/day. Lipid production of Nostoc muscorum during cultivation in BG-II for 14 days decreased day by day. The highest lipid production was reached up in day 4 th of culture that was 9.53 mg/g. Based on this study, Nostoc muscorum has good potential as biodiesel feedstock through producing high biomass in BG-II medium.

Pakan merupakan bagian utama dalam menunjang keberhasilan kegiatan budidaya yang dilakukan. Dengan demikian, diperlukan kajian yang intensif untuk mencari formulasi yang tepat agar tujuan tersebut dapat tercapai secara optimal. Penelitian ini dilakukan untuk menguji persentase yang optimal antara ampas tahu dengan pelet untuk meningkatkan pertumbuhan ikan lele sangkuriang dan menekan biaya pakan seminimal mungkin. Metode analisa data yang digunakan berupa rancangan acak kelompok non-faktorial dengan 5 (lima) perlakuan dan 3 (tiga) kali ulangan, selanjutnya data dianalisis dengan uji F. Perlakuan tersebut berupa: 1) Pakan A: Ampas tahu 80% + pelet 20%; 2) Pakan B: Ampas tahu 60% + pelet 40%; 3) Pakan C: Ampas tahu 40% + pelet 60%; 4) Pakan D: Ampas tahu 20% + pelet 80%; dan 5) Pakan E: Pelet 100% (kontrol). Parameter penelitian meliputi efisiensi pakan, laju pertumbuhan ikan, dan kelangsungan hidup. Hasil penelitian menunjukkan bahwa nilai efisiensi pakan terbaik pada pakan kontrol (pelet) sebesar 77,61%, laju pertumbuhan harian ikan lele sangkuriang yang terbaik diperoleh dari pakan pelet (kontrol) sebesar 3,64%. Sementara untuk kelangsungan hidup yang terbaik didapat pada perlakuan pakan B dan C yaitu sebesar 100%.Feed is a major part in the success of farming activities undertaken. Thus, the necessary intensive study to find the right formulation so that these objectives can be achieved optimally. This study was conducted to test the optimal percentage of tofu by product (TbP) with the pellets to increase fish growth and suppress catfish feed costs to a minimum. Data analysis method used in the form of non-factorial randomized design with 5 (five) treatments and 3 (three) replications, then the data were analyzed by F test. These treatments include: 1) Feed A: TbP 80% + 20% pellets; 2) Feed B: TbP 60% + 40% pellets; 3) Feed C: TbP 40% + 60% pellets; 4) Feed D: TbP 20% + 80% pellets; and 5) Feed E: Pellet 100% (control). Parameter research include feed efficiency, growth rate of fish, and survival. The results showed that the best feed efficiency in the control diet (pellets) amounted to 77.61%, daily growth rate of fish catfish are best obtained from feed pellets (control) of 3.64%. While survival is best obtained at treatment of feed B and C equal to 100%.

The purpose of this study was to determine the effectiveness of Spirulina platensis for remediation of vannamei shrimp culture waste. The method used in this study was a Non-Factoral Completely Randomized Design (CRD) with 4 treatments and 3 replications, namely (A) Control; (B) 50% waste (1500 ml waste + 1500 ml water) + technical fertilizer + Spirulina inoculant; (C) 75% waste (2,250 ml of waste + 750 ml of water) technical fertilizer + Spirulina inoculant; (D) 100% waste + technical fertilizer + Spirulina inoculant. Data analysis used ANOVA with 95% confidence level. The results showed that the use of Spirulina platensis as a remediation agent for vaname shrimp culture had a significant effect on reducing levels of waste ammonia, phosphate, nitrate, and density of Spirulina platensis (Fcount > Ftable 0.05).Keywords: Bioremediator; Innoculant; Vanname shrimp; Waste water

Floating net cage activities can cause  water quality to decrease. The feed remains and the metabolism of the fish  from these activities produces nitrogen and phosphorus .  The objective of this study  is to obtain the calculation model and the amount of phosphorus released into the waters of Laut Tawar Lake  as a result of floating  cage activities. The resulting  formula  was Pw = (F x [P]p) – ((It – Io) x [P]i), where their variables were given feed (F), phosphorus concentration of feed ([P]p), the final weight of fish (It), the initial weight of fish (Io), and phosphorus concentration in fishes ([P]i). It can be used to predict the increase in phosphorus waste based on the increase in floating net cage area. The weight of tilapia increases exponentially with the  day of cultivation in the equation Y = 12.70e0.02x and the goldfish followed the formula  Y = 2.28e0.03x. Phosphorus in tilapia varies  from 1.58% to 2.23% with an average of 1.97%. Goldfish contain  1.19 - 2.02% phosphorus, with an average of 1.52%. Goldfish  growth  was not optimal due to inadequate feeding,   so  without excessive feeding and did not generate  phosphorus waste. The cultivation of  tilapia releases  0.09 Kg P/m2 of phosphorus waste from floating cages .

The trophic status of Laut Tawar Lake was increasingly leading to an alarming level of degradation. Efforts to anticipate an increase in trophic status require scientific knowledge of the trophic phenomena of the waters empirically. This research examines the trophic status parameters to produce a model of the trophic status of Laut Tawar Lake. The proposed model was a modification of Carlson's Trophic State Index Method. Analysis of the relationship examined the interaction of water clarity (SD) with chlorophyll-a (Chl), Total Suspended Solid, and Total Dissolved Solids, and the interaction of chlorophyll-a with nutrient concentration (TP, TN). Data were analyzed descriptively quantitatively, correlation, and regression. The results showed that the waters of Laut Tawar Lake contain phosphate (TP) 34 µg/L, Total Nitrogen 687 µg/L, chlorophyll-a 10 µg/L, Total Suspended Solid 47 mg/L, Total Dissolved Solid 84 mg/L, and water clarity 4.0 m. The regression test showed that the abundance of phytoplankton (Chl) was affected by nutrient phosphate with the empirical model equation Chl = 0.565 TP – 9.161. Nitrogen nutrients did not partially affect the concentration of chlorophyll-a in the waters of Laut Tawar Lake. Water clarity is influenced by chlorophyll-a and TSS, where TDS has no effect partially. The empirical model obtained is Ln SD = 1.757 – 0.013 Chl – 0.008 TSS. Modification of Carlson's TSI by substituting the two equations obtained the equation TSIdlt = 13.46 + 8.08 ln TP + 0.04 TP + 0.04 TSS. This model simulation gives an estimation rate of 91.06%.