POTENSI BUDIDAYA IKAN BANDENG SEBAGAI PEMANFAATAN PLANKTON DI PERAIRAN BATU NAMPAR

Perairan Teluk Ekas telah memiliki konsentrasi nutrien yang di atas ambang batas. Nutrien berasal dari pakan ikan rucah yang diberikann oleh pembudidaya ikan sistem Karamba jaring Apung. Nutrien yang berlebihan di perairan akan memicu pertumbuhan besar-besaran plankton atau yang dikenal dengan blooming. Blooming plankton akan berdampak buruk pada biota yang dibudidayakan serta untuk semua organisme yang mendiami perairan tersebut. Plankton yang tumbuh dapat dikendalikan dengan memberikan organisme yang dapat memanfaatkan keberadaannya sebagai pakan. Bandeng banyak digunakan sebagai pemanen /pemanfaatan plankton baik di perairan tawar maupun laut. Bandeng merupakan ikan euryhalin atau memiliki rentang salinitas yang luas. Selain itu ikan bandeng merupakan ikan ekonomis penting. Namun sebelum mengintroduksi ikan bandeng di KJA Batu Nampar perlu dilakukan analisa kesesuaian beberapa parameter lingkungan dan yang tidak kalah pentingnya adalah jenis plankton yang bisa dimanfaatkan oleh bandeng. Oleh karena itu tujuan penelitian ini adalah mengiventaris/mendata jenis plankton di perairan Batu Nampar serta melihat kesesuaian jenis plankton yang ada dengan yang menjadi pakan ikan alami Bandeng. Metode yang digunakan dalam penelitian ini adalah metode survey. Pengamatan lebih dititikberatkan pada pendataan jenis plankton. Pengambilan contoh air dan pengamatan terhadap parameter-parameter kualitas air lainnya dilakukan pada tiap bulan selama 3 kali. Jenis plankton yang teriventarisir pada saat penelitian adalah: Synedra ulna, Fragilaria, Hemiaulus sinensis, Skeletonema costatum, Triceratium taves, Coscinodiscus granii, Pseudo nitzschia, Dytilum sol, Cerataulina smithii, Clamydocapsa sp, Navicula elegans, Aulacodiscus gracilis, Cydotella sp., Globorotolia pumilio, Ceratium sp.,larva crustacean, Pontellina plumata. Plankton yang terdapat lebih banyak dari Bacillariophyceae yang merupakan jenis pakan dari ikan bandeng sehingga perairan KJA Batu Nampar berpotensi digunakan untuk budidaya Bandeng

Seasonal Shift of a Phytoplankton (>5 µm) Community in Bohai Sea and the Adjacent Yellow Sea

In order to better understand the seasonal variations in the phytoplankton community structure in the Bohai Sea (BS) and the North Yellow Sea (NYS), we carried out three cruises during 12 to 24 April 2019, 8 to 18 June 2019, and 12 to 22 October 2019. A total of 212 taxa (75 genera and three phyla) were identified, among which 83 taxa in 40 genera, 96 taxa in 43 genera, and 151 taxa in 62 genera were found in spring, summer, and autumn, respectively. Diatoms including Paralia sulcata and Coscinodiscus granii were the most dominant phytoplankton group during the three seasons, while several species of dinoflagellates, e.g., Scrippsiella troichoidea, Tripos massiliensis f. armatus, Gyrodinium spirale, and Prorocentrum minimum were found in warmer, saltier, and nutrient-poor waters. The diversity index of phytoplankton community was highest in autumn and lowest in summer. Based on cluster and multidimensional scaling analyses, the phytoplankton community of the BS and the NYS was divided into three ecological provinces: the BS, the coastal area, and the NYS. These three ecological provinces differed in physicochemical properties induced by the complicated water masses and circulations. Due to the influence of nutrient concentration, the phytoplankton diversity had the highest value in autumn, followed by spring, and the smallest in summer.

The oomycete Lagenisma coscinodisci hijacks host alkaloid synthesis during infection of a marine diatom

Flagellated oomycetes frequently infect unicellular algae, thus limiting their proliferation. Here we show that the marine oomycete Lagenisma coscinodisci rewires the metabolome of the bloom-forming diatom Coscinodiscus granii, thereby promoting infection success. The algal alkaloids β-carboline and 2,3,4,9-tetrahydro-1H-β-carboline-3-carboxylic acid are induced during infection. Single-cell profiling with AP-MALDI-MS and confocal laser scanning microscopy reveals that algal carbolines accumulate in the reproductive form of the parasite. The compounds arrest the algal cell division, increase the infection rate and induce plasmolysis in the host. Our results indicate that the oomycete manipulates the host metabolome to support its own multiplication.

Struktur Komunitas Plankton sebagai Indikator Kualitas Perairan Budidaya di Tambak Lorok Semarang

Plankton is organisms that had an important role in water as natural feed of fishes and as an indicator. This study aimed to identify water quality which was suitable for fish cultivation reviewed from physics-chemicals parameters of water and its saprobic status in Tambak Lorok Tanjung Mas Kota Semarang. Sampling were take based on 5 stations that could represented from plankton variety of condition water stability . Plankton samples were by using net plankton number 25, then preserved with alcohol 70% and formalin 4%. Variables of ponds water quality measured were temperature, salinity, dissolved oxygen, pH, turbidity, N concentration, and Pb content. Identification of planktons used SRC method under microscop. The result of plankton analysis in Tambak Lorok water showed 42 phytoplankton species, the commonly species found are Coscinodiscus centralis, Coscinodiscus granii, Gyrosigma sp., Navicula radiosa, Pandorina sp., and Melosira sp. Meanwhile, zooplankton found was 22 species with common species are Cyclops, Harpaticoida, Tricodesmium evythraeum, Brachinus plicatilis, and Lensia subtilis. Phytoplankton diversity index are 0.057-0.367 and equity index are 0.025-0.176. Zooplankton diversity index are 0.247-0.360 and equity index are 0.157-0.201. This indices showed that there were low level of species diversity and community stability, dominance since the species occurred. Measurement of water quality variables indicated that Tambak Lorok had been contaminated and needed a preliminary management before d be used as fish cultivation ponds, because the analysis result was not appropriate with Government water quality regulation. Based on the measurement, soprobic index categories on α/β-Mesosaprobic to Oligosaprobic phase and the degree of pollution is very mild to moderate. Keywords : Community Structure, plankton, Tambak Lorok, Tanjung Mas, Semarang

Differences in the optical properties of valve and girdle band in a centric diatom

Diatoms are phototrophic single-celled microalgae encased in a cell wall (frustule) made of amorphous silicate. The frustule comprises two valves connected by a variable number of girdle bands, all exhibiting periodic micro/nanoporous structures. We studied the optical properties in water of girdle bands from the centric diatom Coscinodiscus granii , a frustule part that so far has received little attention by the scientific community. We show that valves and girdle bands exhibit different optical properties, as valves attenuate shorter wavelengths and girdle bands attenuate longer wavelengths of the visible light spectrum. Girdle bands show iridescent coloration in dependence of the light direction. Although the biological meaning of periodic nanoscale structures of frustules is still a matter of debate, the differences of valve and girdle band optical properties indicate that living diatoms are complex optical systems, where valves, girdles and pigments modulate light inside the cell.

Presence and Composition of Planktons’ Organisms in Ships Ballast Water Discharged in Al-Mukalla Harbor, Gulf of Aden

This was the first study in Yemen, and Gulf of Aden aims to investigate the marine organisms in ballast water and sediments, and gives baseline information defines the zooplankton, phytoplankton and invertebrates, associated fuel tankers. Samples from Ballast water were taken from three ships that arrived at Mukalla Port, the Hadhramout coast from ports of Hamriyah port, U.A.E; ports of Taheri, Iran; and Bosaso Somalia (MT: Gulf Petroleum III, MT: Prime Royal, and M T: Breu) respectively. The marine organisms in samples were presented by three taxonomic groups, phytoplankton, zooplankton and benthos. Fifty-eight taxa were identified within this study; which consisted of 17 phytoplankton, 18 zooplanktons and 23 Benthos. The highest density of phytoplankton was 21 Ind/L, with the occurrence of 17 species found in ballast water, while 22 Ind/50cc of 2 species in sediment samples of the tanker Beru, and fewer densities were in Gulf Petroleum and Prim Royal. The most common phytoplankton observed were Coscinodiscus granii, Coscinodiscus jonesianus and Thalassiosira eccentric. The low Zooplankton density was 13 Ind/L with an occurrence of 18 species found in Prim Royal tanker. Copepods were the most dominant zooplankton among the three tankers. Paracalanus parvus had the highest value of dominance followed by Calanopia parathompsoni, Acrocalanus gracilis and Paracalanus denudatus had the lowest occurrence over three tankers. Seven taxa of Dinoflagellates were identified; two of them Ceratium fusus and polykrikos sp. are known to be harmful species.