ABSTRAKDanau Toba merupakan danau terbesar di Indonesia yang terletak di Provinsi Sumatera Utara. Danau Toba banyak dimanfaatkan oleh masyarakat untuk kegiatan budi daya ikan di keramba jaring apung (KJA), pertanian, pariwisata, dan pemukiman penduduk. Aktivitas-aktivitas tersebut akan memberikan masukan berupa bahan organik dan anorganik yang akan memengaruhi kualitas air dan dapat menyebabkan terjadinya eutrofikasi. Beberapa indikator eutrofikasi adalah terjadi peningkatan biomassa fitoplankton dan perubahan struktur komunitas fitoplankton. Tujuan dari penelitian ini adalah untuk mengkaji struktur komunitas fitoplankton di Danau Toba. Penelitian ini dilakukan pada tanggal 2024 Oktober 2014 di 23 stasiun di perairan sekitar Pulau Samosir, Danau Toba. Hasil penelitian menunjukkan bahwa kelimpahan fitoplankton berkisar antara 216-68.319.716 sel/m 3 . Komposisi fitoplankton terdiri dari 35 genus dari empat kelas, yaitu Cyanophyceae, Chlorophyceae, Bacillariophyceae, dan Dinophyceae. Cyanophyceae merupakan kelas fitoplankton yang dominan berdasarkan komposisi kelimpahannya (>40%). Struktur komunitas fitoplankton di Danau Toba didominasi oleh Anabaena.Kata kunci: danau toba, fitoplankton, struktur komunitas ABSTRACT Lake Toba is the largest lake in Indonesia, located in the Province of North Sumatra. Lake Toba is used to aquaculture, agricultural, tourism, and residential areas. These activities will produce organic and anorganic matter that can affect water quality and can cause eutrophication. Some indicators of eutrophication are an increase in phytoplankton biomass and changes in phytoplankton community structure. The aim of this study was to describe the phytoplankton community structure in Lake Toba. This study was conducted on 2024 October 2014 at 23 stations around the Samosir Island, Lake Toba. The results showed that the phytoplankton abundance ranged 216-68.319.716 cells/m 3 . The phytoplankton composition consists of 35 genera from four classes: Cyanophyceae, Chlorophyceae, Bacillariophyceae, and Dinophyceae. Cyanophyceae is a dominant phytoplankton groups based on the composition of abundance (>40%). Structure of phytoplankton communities in Lake Toba dominated by Anabaena.

The case of stunting in Indonesia was higher and still becomes an important issue in poor rural areas. Research objective is to examine the prevalence rate and associated factors with stunting in children aged 6-59 months in rural areas of Bantul, Yogyakarta, Indonesia. This study applied a case-control design. The cases group were stunted children and the control group was not stunted children from October to December 2018. The data was collected by interviewing selected mothers of 6-59 months children and measuring the length/height of 23 children as a case group and 91 children as a control group. Research location used two rural areas in Bantul Yogyakarta. This study used logistic regression analysis to identify the best model of factors leading to stunting in rural areas. Analysis to measure of association used 95% CIs and "Adjusted" ORs. The prevalence of stunting was 20.8% out of which 52.2% were mild, 4.3% were moderate and 43.5% were severe. The mean of children age in the case and control group were 31.78 16.8 and 29.92 15.96 months with the mean of height for age Z score were-3.23 1.03 and-0.14 1.22 respectively. Diarrhea was found significantly as the determinant factor of stunted children in rural areas (AOR=7.79, 95% CI 2.59-23.33, p = 0.001). The results showed diarrhea as determinants factor of stunting in children under five in rural areas, it is important to assist the Indonesian government to develop a program to address the problem of stunting associated with the environment

Abstract. Sulardiono B, Anggoro S, Rudiyanti S, Rahman A. 2019. Assessment of the Holothuria atra (Echinodermata: Holothurians) habitat based on the antibacterial effectiveness approach at Karimunjawa, Central Java Province, Indonesia. Ocean Life 3: 11-17. Sea cucumber Holothuria atra lives in shallow marine benthic habitats and in its life cycle depends on the quality of its environment. Bacteria in the body of sea cucumbers come from the bioaccumulation of bacteria in the sediment that they exposed to through the process of absorption of sediments as a deposit feeder. To inhibit bacterial growth in the body, sea cucumbers release bioactive compounds as antibacterial. The purpose of the study is to determine the effectiveness of sea cucumber inhibition ability of sea cucumber H. atra as an antibacterial in the waters of Karimunjawa. A total of 15 individual sea cucumbers were taken from the waters of Menjangan Besar and 20 individuals from the Alang-alang waters, then cleaned and dissected to take the part of the body wall. The body wall samples obtained from each observation station was as much as 1 kg, which was then sliced into small pieces and preserved in 96% ethanol, and and the bioactive compound was extracted by maceration method. Antibacterial activity test was carried out by disc diffusion method on paper discs (10mm) and using the media of EMBA (Ethylene Methyl Blue Agar) (Merck) for E. coli bacteria and BPA (Baird Parker Agar) for S. aureus bacteria. The obtained antibacterial test results were based on the measurements of the formed clear zone diameter, so that it can be known the effectiveness status of the antibacterial sea cucumbers of each observation station. The results of the study show that the antibacterial effectiveness of sea cucumber H. atra in the Menjangan Besar waters is higher than in the Alang-alang waters. The increase of sea cucumber bioactive compounds in the waters of Menjangan Besar shows that the waters are suitable for the development zone of sea cucumber cultivation

Pencemaran nitrogen secara global begitu meningkat akibat pembuangan air limbah organik bersumber dari aktivitas manusia yang mencemari lingkungan perairan. Peningkatan senyawa nitrogen secara terus menerus dan dalam waktu yang lama menjadi penyebab terjadinya eutrofikasi dan kematian organisme. Proses reduksi nitrogen pada air limbah dapat dilakukan secara ekonomis dan efisien menggunakan bakteri nitrifikasi-denitrifikasi. Teknologi ramah lingkungan yang juga dapat digunakan adalah bioremediasi menggunakan mikroalga seperti Chlorella sp. Adanya hubungan sinergis dari bakteri dan mikroalga berpotensi meningkatkan kinerja reduksi senyawa nitrogen pada air limbah organik. Penelitian yang dilakukan pada bulan Juli hingga Agustus 2020 ini, bersifat eksperimental laboratoris menggunakan Rancangan Acak Kelompok, bertujuan untuk mengetahui laju nitrifikasi dan perubahan kadar nitrat, laju pertumbuhan Chlorella sp., serta pengaruh perbedaan perlakuan dan waktu terhadap perubahan kadar nitrat pada air limbah organik dan hubungan Chlorella sp. dengan bakteri nitrifikasi-denitrifikasi. Air limbah yang diambil berasal dari danau Rawa Pening. Hasil penelitian menunjukkan, laju nitrifikasi secara berturut-turut dari yang tertinggi hingga terendah yaitu perlakuan C 0,2 mg NH4-N/liter/jam, diikuti perlakuan B, D dan A masing-masing 0,169, 0,009 dan 0,008 mg NH4-N/liter/jam. Pola pertumbuhan Chlorella sp. mengalami peningkatan hingga hari puncak (hari ke 6) dan menurun hingga hari terakhir. Persentase perubahan kadar nitrat dari awal hingga akhir pengamatan dari yang tertinggi secara berurutan yaitu perlakuan C (1874%), B (1664%), D (200%) dan A (175%). Hasil analisis sidik ragam menunjukkan terdapat perbedaan antara perlakuan terhadap perubahan kadar nitrat (p value <0,05). Hasil Uji DMRT menunjukkan rata-rata perubahan tertinggi adalah perlakuan C, B, D dan A.

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