In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries.

Background and aims – The present study aims to describe a new species of pennate blue diatom from the genus Haslea, H. nusantara sp. nov., collected from Semak Daun Island, the Seribu Archipelago, in Indonesian marine waters. Methods – Assessment for species identification was conducted using light microscopy, Scanning Electron Microscopy and molecular techniques. The morphological characteristics of H. nusantara have been described, illustrated and compared to other morphologically similar blue Haslea taxa, distributed worldwide. Additionally, molecular characterization was achieved by sequencing plastidial and mitochondrial genomes. Key results – This new species, named Haslea nusantara, cannot be discriminated by its morphology (stria density) but it is characterized by its gene sequences (rbcL chloroplast gene and cox1 mitochondrial gene). Moreover, it differentiates from other blue Haslea species by the presence of a thin central bar, which has been previously reported in non-blue species like H. pseudostrearia. The complete mitochondrion (36,288 basepairs, bp) and plastid (120,448 bp) genomes of H. nusantara were sequenced and the gene arrangements were compared with other diatom genomes. Phylogeny analyses established using rbcL indicated that H. nusantara is included in the blue Haslea cluster and close to a blue Haslea sp. found in Canary Islands (H. silbo sp. ined.). Conclusions – All investigations carried out in this study show that H. nusantara is a new blue-pigmented species, which belongs to the blue Haslea clade, with an exceptional geographic distribution in the Southern Hemisphere.

AbstrakPenelitian ini bertujuan untuk melakukan monitoring kualitas air di tambak budidaya udang vaname, membandingkan efektivitas penerapan budidaya dengan sistem pemeliharaan berbeda pada tambak dan variasi pemberian pakan. Pada kegiatan ini, empat tambak budidaya digunakan sebagai tempat pembesaran udang vaname (Litopenaeus vannamei). Parameter yang diukur meliputi parameter fisika dan kimia yaitu suhu, kecerahan, pH, oksigen terlarut, salinitas, amonia, dan alkalinitas; sedangkan performa pertumbuhan organisme budidaya dilihat dengan cara menghitung tingkat kelulushidupan (survival rate) udang pada akhir pemeliharaan, efisiensi konsumsi pakan melalui perhitungan FCR, dan laju pertumbuhan spesifik udang (SGR) dengan menghitung ABW (Average Body weight) dan ADG (Average Daily Growth) udang. Hasil penelitian menunjukan bahwa secara keseluruhan kisaran kualitas air yang diperoleh masih dalam keadaan layak untuk kegiatan budidaya dan bahkan Tambak 3 dan 4 menunjukkan kisaran optimum untuk kualitas air budidaya, sedangkan untuk parameter performa pertumbuhan, pada Tambak 3 dan 4 diperoleh nilai SR lebih dari 80 %, dan Tambak 1 dan 2 mempunyai SR di bawah 70 %. Selain itu, nilai FCR berada di bawah 1.7 pada tambak 3 dan 4, sedangkan pada Tambak 1 dan 2 nilainya lebih dari 1.7. Terakhir untuk nilai SGR, Tambak 3 dan 4 juga menunjukkan presentasi yang bagus jika dibandingkan Tambak 1 dan 2. Secara komprehensif, dapat disimpulkan bahwa penerapan sistem pemeliharaan dengan menggunakan sistem flok pada Tambak 3 dan 4 meningkatkan performa kualitas air dan hasil produksi dibandingkan pada Tambak 1 dan 2.                                                                 AbstractThe aim of this study was to monitor water quality in vaname culture pond and compare the application of different rearing culture system and feeding variations. Four ponds culture were used as vaname (Litopenaeus vannamei) growth place. Measured parameters include physical and chemical factors such as temperature,brightness, pH, DO, salinity, ammonia, and alkalinity, while growth shrimp performance showed by SGR, SR and FCR. The research result of the water quality parameters show an adequate range values for all of the ponds and good enough for shrimp growth, and especially an optimum range value presented in pond three and four. Survival rate (SR) both pond 3 and 4 exhibit a good presentation that is more than 80%, whereas pond 1 and 2 were just less than 70% of SR value. The specific growth rate (SGR) presents also a good presentation in Pond 3 and 4 rather than pond 1 and 2. Based on the feed consumption, pond 1 and 2 show high FCR that is more than 1.7 while pond 3 and 4 present smaller FCR value which is less than 1.7. Finally, it could be concluded that application of floc in culture rearing system of pond 3 and 4 increase water quality and production value than pond 1 and 2.