Bakteri merupakan mikroorganisme yang secara alami berada dalam ekosistem perairan laut dan beberapa spesiesnya bersifat patogen. Penelitian ini bertujuan untuk menentukan pola fluktuasi populasi bakteri secara umum dan Vibrio spp. secara khusus di perairan pantai dan teluk sebagai dampak dari aktivitas baik panti pembenihan, tambak udang, maupun karamba jaring apung (KJA) di pesisir Bali Utara. Sampel air diperoleh dari tiga lokasi sentra budidaya laut dan satu lokasi ekowisata yang berada di Kecamatan Gerokgak Kabupaten Buleleng. Sampel air diambil dari tiga titik sampling di perairan dengan jarak 50 m, 100 m, dan 300 m dari garis pantai di Desa Gerokgak dan Desa Penyabangan. Sampling air dilakukan pada tiga titik sampling di sekitar KJA di Teluk Kaping, Desa Sumberkima, dan satu titik sampling di perairan dengan jarak 100 m dari garis pantai di Desa Pemuteran. Sampling air dilakukan sekali dalam sebulan dari bulan Februari hingga November 2018. Hasil penelitian menunjukkan bahwa total bakteri dan Vibrio spp. di empat lokasi perairan di Kecamatan Gerokgak, Bali menunjukkan populasi tinggi pada bulan Maret hingga Mei dan menurun pada bulan berikutnya. Dan meningkat kembali pada bulan Oktober hingga November. Total bakteri dan Vibrio spp. tertinggi terjadi di perairan pantai Desa Gerokgak hingga 9.067 ± 7.481 CFU/mL dan 1.147 ± 689 CFU/mL dibandingkan dengan dua lokasi sentra budidaya lainnya (Desa Penyabangan dan Teluk Kaping). Total bakteri dan Vibrio spp. teramati pula di perairan Desa Pemuteran hingga 500 ± 52 CFU/mL dan 65 ± 7 CFU/mL yang kemungkinan merupakan dampak dari aktivitas budidaya ikan. Pola fluktuasi populasi bakteri di perairan pantai Kecamatan Gerokgak, Bali dipengaruhi oleh musim dan kegiatan budidaya perikanan. Tingginya populasi bakteri Vibrio spp. pada perairan pantai dapat memengaruhi kesehatan ikan budidaya.Bacteria are a group of microorganisms naturally present in aquatic ecosystems. Some of the bacteria are pathogenic to other organisms and cause severe diseases. This study aimed to determine the fluctuation patterns of bacterial populations, with specific interest to Vibrio spp. in coastal and bay areas of North Bali which constantly receive effluents from nearby mariculture activities. Water samples were collected from three locations in a clustered marine fish farming area and one location in an ecotourism area as a control. Water samples were taken from three sampling points in the coastal area of Gerokgak and Penyabangan villages at a distance of 50 m, 100 m, and 300 m from the coastline. Water samples were also collected at three sampling points around floating net cages (KJA) in Kaping Bay, Sumberkima Village, and one sampling point in Pemuteran Village located 100 m from the coastline. Water sampling was carried out each month from February to November 2018. Results of the study showed that total bacteria and Vibrio spp. were notably higher between March-May and October-November. The total bacteria and vibrio reached the peak number at 9,067 ± 7,481 CFU/mL and 1,147 ± 689 CFU/mL, respectively, which occurred in the coastal waters of Gerokgak Village. The total bacteria and Vibrio spp. of up to 500 ± 52 CFU/mL and 65 ± 7 CFU/mL, respectively, were also observed in the waters of Pemuteran Village which are likely to be the effects of aquaculture activities in these of three locations. This study concludes that the fluctuation pattern of bacterial population in the coastal waters of Gerokgak District, Bali is primarily influenced by the season and activities of the fish farming. The high population of Vibrio spp. in the coastal waters could lead to a fish disease oubreak related to the pathogenic bacterium.
ABSTRAKIkan kerapu raja sunu (Plectropomus laevis) merupakan komoditas ekspor yang bernilai ekonomis tinggi di pasar Asia, namun stoknya di alam sudah langka. Pemberian pakan buatan dalam pemeliharaan larvanya telah dilakukan, namun waktu respon awal larva terhadap pakan buatan secara tepat belum diketahui. Penelitian ini bertujuan untuk mengetahui waktu awal pemberian pakan buatan yang efektif pada pemeliharaan larvanya. Tiga perlakuan pemberian pakan buatan yang diuji yaitu mulai umur 7 hari (D-7) (A), D-10 (B), dan D-13 (C). Parameter yang diamati meliputi perkembangan panjang total, sintasan larva, jumlah rotifer dalam lambung dan histologi organ pencernaan larva. Penelitian berlangsung sampai larva berumur 43 hari, menggunakan rancangan acak kelompok (RAK) dengan tiga kelompok waktu untuk setiap perlakuan. Hasil penelitian menunjukkan bahwa perbedaan waktu awal pemberian pakan buatan berpengaruh terhadap sintasan dan pertumbuhan larva. Panjang total dan sintasan larva umur 43 hari yang tertinggi dicapai pada perlakuan B yaitu 29,3 mm ± 0,36 mm dan 2,61% ± 0,21%; diikuti oleh perlakuan C dengan nilai 28,0 mm ± 0,85 mm dan 1,55% ± 0,18%; dan yang terendah pada perlakuan A adalah 27,0 mm ± 0,25 mm dan 0,85% ± 0,13%. Data ini menunjukkan bahwa waktu awal pemberian pakan buatan yang terbaik adalah mulai larva berumur 10 hari. KATA KUNCI: kerapu raja sunu, larva, pakan buatan ABSTRACT:Larval rearing of blacksaddled coral grouper (Plectropomus laevis) with different initial feeding time with artificial diet. By: Bejo Slamet, Titiek Aslianti, Ketut Maha Setiawati, Wawan Andriyanto, and Afifah Nasukha Blacksaddled coral grouper (Plectropomus laevis) is an export commodity and has high economic value in Asian markets. Wild population of this grouper was already threatened. Trial on aplication of artificial diet on Blacksaddled coral grouper larval rearing in hatchery have been conducted, however the exactly time for the initial feeding response not knew yet. The purpose of the present study is to know the effect of initial feeding with artificial feed on survival rate and growth of Blacksaddled coral grouper larvae. Three feeding time experiments have been conducted namely: artificial feed start from 7 days old larvae (D-7) (A), D-10 (B) and D-13 (C). The experiment was conducted in three PENDAHULUANIkan kerapu raja sunu (Plectropomus laevis) merupakan komoditas ekspor yang bernilai ekonomis tinggi di pasar Asia. Saat ini stok ikan kerapu raja sunu di alam sudah sangat langka sebagai akibat penangkapan yang berlebihan. Usaha ke arah budidaya ikan ini perlu dilakukan dalam rangka perlindungan populasinya di alam, pemenuhan kebutuhan pasar dan diversifikasi usaha budidaya ikan kerapu. Usaha pembenihan ikan kerapu raja sunu perlu dilakukan dalam rangka pemenuhan kebutuhan benih pada upaya budidayanya.
Buangan limbah organik dari kegiatan budidaya ikan berdampak pada naiknya konsentrasi senyawa nitrogen di perairan. Tujuan penelitian ini adalah untuk mengetahui sebaran vertikal konsentrasi total nitrogen (TN), total fosfat (TP), dan amonia pada perairan pesisir yang berdekatan dengan kawasan budidaya ikan laut di Bali Utara. Titik sampling dipilih pada kedalaman 5, 10, 15, 20, dan 30 meter dengan arah tegak lurus garis pantai di kawasan perbenihan ikan dengan tingkat aktivitas tinggi (Desa Gerokgak dan Desa Penyabangan) dan tiga titik sampling di sekitar karamba jaring apung (KJA) di Teluk Kaping, Desa Sumberkima. Sampel air diambil pada bagian permukaan, tengah, dan dasar pada tiap titik sampling. Penelitian ini dilakukan pada tahun 2019 dengan dua periode waktu yaitu bulan April sampai Juni dan Agustus sampai Oktober dengan satu kali pengambilan contoh air setiap bulan. Hasil penelitian menunjukkan bahwa sebaran konsentrasi TN, TP, dan amonia secara vertikal cenderung homogen pada tiap titik pengamatan. Konsentrasi TN, TP, dan amonia selama penelitian berturut-turut adalah 1,2-1,5 mg/L; 0,081-0,090 mg/L; dan 0,054-0,057 mg/L. Nilai tersebut berada di bawah baku mutu air untuk kebutuhan budidaya ikan. Sebaran konsentrasi senyawa nitrogen dan fosfat secara vertikal di lokasi penelitian relatif homogen pada semua lapisan kedalaman air yang diamati. Kondisi tersebut menunjukkan bahwa proses percampuran masa air terjadi secara merata di kawasan tersebut. Kualitas perairan di lokasi penelitian masih sesuai dengan nilai baku mutu untuk kegiatan budidaya laut.Direct discharge of organic waste from aquaculture platforms is likely to increase nitrogen concentration in the surrounding waters. The study aimed to investigate the vertical distribution of total nitrogen (TN), total phosphorus (TP), and ammonia concentration in the coastal waters adjacent to the three densest mariculture sites in North Bali (Gerokgak, Penyabangan, and Kaping Bay). Field surveys were conducted six times within two periods namely April to June and August to October 2019. Samples of different water columns (surface, middle, and bottom) were collected using a Nansen water sampler in each sampling point. The samples were immediately analyzed at the Research Institute for Mariculture and Fishery Extension, Gondol. Total nitrogen, total phosphate, and ammonia were analysed using sulfuric acid destruction and distillation, nitrate-acid destruction, and phenol-spectrophotometer, respectively. The result showed that TN, TP, and ammonia levels were 1.2-1.5 mg/L, 0.081-0.090 mg/L, and 0.054-0.057 mg/L, respectively. The vertical distribution of nitrogen and phosphorus compounds at all layers of water column were relatively homogenous indicating a strong mixing between the seawater layers. Thus, the study concludes that the variations of all water quality parameters are within the water quality standard needed for mariculture activities.
<p>The milkfish (<span style="text-decoration: underline;">Chanos</span> <span style="text-decoration: underline;">chanos</span> Forsskal) seed quality is an important factor for supporting the fisheries industrialization program . The egg fertility and larval rearing management are two main factors to improve the quality of the seed. The aim of this research was to obtain the information about those two indicators on milkfish larvae, reared in different media. About 100,000 eggs were located in 6 units of the outdoor concrete tank with volume of 6 m<sup>3</sup>. Larvae were reared due to the rearing standard procedure while the feeding management was adapted during larvae development. Two different treatments in larval rearing medium were with and without the addition of molasses, subsequently in triple trials. This study started from hatching day (0 DAH) until the end of larval rearing period (16-18 DAH). The growth parameters such as vertebrae analyses and survival were taken in the end of research periods, while protease assessment was analyzed every day using tyrosine and casein standard methods. The results showed that the molasses addition produced a higher growth (TL 12.95±0.87 mm) and survival rate (87.66±1.52%), better vertebral performance (44-45 segments), and higher protease activity (0.1392-0.3863 U/ml/min) than without molasses addition. The results indicated that molasses addition in larvae rearing medium improved the larvae quality.</p> <p>Keywords: Protease enzime activity,milkfish seeds, molasses, vertebrae</p>
Indonesia is globally known as the third biggest grouper producer, but its production lately raises some environmental concerns. Aims of this study were identification of nitrogen and phosphorus concentrations derived from feed and metabolism of hybrid grouper. Simple vessels were built and arranged into five main components in culture system: culturing tank, sedimentation, oxygenation, reservoir and filtration. Two sets of systems were used as study replications. Twenty juveniles of the hybrid were stocked in 100 L culture tanks and fed to satiation. Four testing times were taken: at initial (0), 1, 3 and 6 hours after feeding. Results showed that nitrogen contents (ammonia, nitrite, nitrate and total nitrogen was performing nitrogen cycle starting from 0 and peaked at 3 to 6 hour after feeding time. The highest values were majority found in culture tank at 0.08; 0.0015; and 1.372 ppm for ammonia, nitrite and nitrate, respectively. The highest values of total nitrogen and total phosphates were 1.9 and 0.33 ppm that slightly fluctuated over the period even though still in fair values. This study also documented that feeding intake was relatively high (14.78% of feed/BW) that may indicate greater degree in generating solid waste materials to water media.
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