ABSTRACT   The objective of this research was to determine the optimum level of organic selenium supplementation in improving the growth performance of Nile tilapia Oreochromis niloticus fed with diet containing low protein level. Basal diet was formulated to contain 28% protein with three different levels of organic selenium supplementation, namely 0 (control), 3, and 6 mg Se/kg feed. Furthermore, to evaluate selenium function on protein utilization and sparring effect, a diet with 30% of protein content was also used as a comparison. In this regard, this study was conducted using a completely randomized experimental design with four treatments and three replications. Nile tilapia with an average body weight of 8.05 ± 0.25 g were reared in the 100×50×50 cm3 aquarium at a density of 15 fish/aquarium. The experimental fish were reared for 60 days and fed three times daily to apparent satiation levels. Dietary supplementation of organic Se resulted in higher fish biomass, lower feed conversion ratio, higher protein retention and daily growth rate compared to the control diets with 28% and 30% protein levels. In conclusion, dietary supplementation of organic Se at 3 mg organic Se/kg feed could significantly increase protein utilization and improve the growth performance of Nile tilapia.   Keywords: tilapia, protein sparing effect, organic selenium, feed   ABSTRAK   Tujuan dari penelitian ini adalah menentukan tingkat suplementasi selenium organic pada pakan untuk meningkatkan kinerja pertumbuhan ikan nila Oreochromis niloticus. Pakan basal diformulasikan mengandung 28% protein dengan tiga tingkat selenium organik yaitu 0 (kontrol), 3, dan 6 mg Se/kg pakan. Selanjutnya untuk mengevaluasi penggunaan selenium pada pemanfaatan protein dan efek sparring, pakan dengan 30% protein juga ditambahkan sebagai perlakuan pembanding. Penelitian ini menggunakan rancangan acak lengkap dengan empat perlakuan dan tiga ulangan. Ikan nila dengan bobot rata-rata adalah 8.05 ± 0.25 g dipelihara dalam akuarium 100 × 50 × 50 cm3 dengan kepadatan 15 ikan/akuarium. Ikan dipelihara selama 60 hari dan diberi pakan tiga kali sehari secara at satiation. Pemberian pakan dengan suplementasi Se organic menghasilkan biomassa ikan yang lebih tinggi, rasio konversi pakan yang lebih rendah, retensi protein dan laju pertumbuhan harian yang lebih tinggi daripada perlakuan control dengan kadar protein 28% dan 30%. Berdasarkan hasil penelitian ini, dapat disimpulkan bahwa suplemtasi pakan ikan nila dengan 3 mg Se organik/kg pakan dapat meningkatkan pemanfaatan protein pakan dan kinerja pertumbuhan ikan Nila.   Kata kunci: ikan nila, protein sparing effect, selenium organik, pakan.

The purpose of this study was to determine the antibacterial activity of Caulerpa racemosa sea grapes against several types of bacteria in fish. This research was conducted from June to July 2022 at the Fishery Products Technology Laboratory, Faculty of Fisheries and Marine Science, and Biology Laboratory, Faculty of Matemathics and Natural Science, Pattimura University. This experiment using four kinds of extract concentration were 25%, 50%, 75%, and 100% and amoxicillin (control). Furthermore, to evaluate the antibacterial activity of C. racemosa seaweed extract, an inhibition zone test was performed against Vibrio parahaemolyticus, Escherichia coli, Salmonella thypii and Staphylococcus aureus bacteria which were seen based on the diameter of the resulting inhibition zone. This study used a completely randomized design with four treatments and three replications. The inhibition zone test was carried out for 1 x 24 hours to see the inhibition zones produced from each treatment. The results of the analysis of the concentration of C. racemosaextract gave no significant effect on the inhibition zone of each type of bacteria (p>0.05). However, the treatment of 100% C. racemosa extract showed the highest inhibition zone value among the extract concentrations of 25%, 50% and 75%. V. parahaemolyticus bacteria had the highest inhibition zones followed by S. thypii, E. coli and S. aureus bacteria of 49 mm, 35 mm, 24 mm and 23 mm, respectively. The results of this study indicate that the higher the concentration of the extract, the larger the inhibition zone producedthe higher the concentration of the extract, the larger the resulting inhibition zone.   ABSTRAK Tujuan dari penelitian ini yaitu mengetahui aktivitas antibakteri dari anggur laut Caulerpa racemosa terhadap beberapa jenis bakteri pada ikan. Penelitian ini berlangsung dari bulan Juni sampai Juli 2022 di Laboratorium Teknologi Hasil Perikanan, Fakultas Perikanan dan Ilmu Kelautan, dan Laboratorium Biologi Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Pattimura. Penelitian ini menggunakan empat macam konsentrasi ekstrak 25%, 50%, 75%, dan 100% dan amoxicilin (kontrol). Selanjutnya untuk mengevaluasi aktivitas antibakteri ekstrak rumput laut C. racemosa dilakukan uji zona hambat terhadap bakteri Vibrioparahaemolyticus, Escherichia coli, Salmonella thypii dan Staphylococcus aureus yang dilakukan selama 1x24 jam dilihat berdasarkan diameter dari zona hambat yang dihasilkan dari setiap perlakuan. Penelitian ini mengunakan rancangan acak lengkap dengan empat perlakuan dan tiga kali ulangan. Hasil analisis konsentrasi ekstrak C. racemosa memberikan pengaruh yang tidak berbeda nyata terhadap zona hambat dari setiap jenis bakteri (p>0.05). Perlakuan ekstrak 100% C. racemosa menunjukan nilai zona hambat yang paling tinggi diantara konsentrasi ekstrak 25%, 50% dan 75%. Bakteri V. parahaemolyticus memiliki zona hambat yang paling tinggi dikuti oleh bakteri S. thypii, E. coli dan S. aureus masing-masing sebesar 49 mm, 35 mm, 24 mm dan 23 mm. Hasil dari penelitian ini menunjukkan bahwa semakin tinggi konsentrasi ekstrak, semakin besar zona hambat yang dihasilkan. Kata Kunci:    Caulerpa racemosa, antibakteri, V. parahaemolyticus, E. coli, S. thypii, S. aureus

Water plays an important role in life and is a vital component that supports biodiversity and secures the existence of ecosystems. Water sampling in this study consisted of 13 stations, namely 10 stations in river waters and 3 stations in estuary areas in the waters of Lurang Village, North Wetar District, Southwest Maluku Regency, Indonesia. The water quality parameter measurement results show that the water quality conditions in several locations are below the optimum limit. Heavy metal test samples were taken from 4 locations, namely RW35, RW36, RW39 and RWBG.Ds to be tested for the metal content of Selenium (Se), Cadmium (Cd), Copper (Cu), Lead (Pb) and Mercury (Hg). The presence of heavy metals in waters is a result of pollution from industrial, agricultural and other waste products. This study aims to determine the water quality and distribution of heavy metals in the river and estuary waters in Lurang Village, North Wetar District, West Maluku Regency.