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Arafura Sea is one of the waters in the eastern region of Indonesia that is rich in marine and fisheries potentials because of its fertile conditions which is suitable for fishing ground. One of the fish resources which have important economic value at the Arafura Sea is big pelagic fish such as Mackerel. Thus this study aims to determine the spatial and temporal distribution of Mackerel in the Arafura Sea based on fishing boat coordinate data, to know the distribution of chlorophyll-a concentration and SST from MODIS satellite data in the Arafura Sea and to determine the correlation of chlorophyll-a and SST to the Mackerel catch distribution. This study was conducted in December 2016 until February 2017 in the Arafura Sea, image data analysis of MODIS level-3 conducted at the Laboratory of Oceanography FPIK UNDIP. The data used are Mackerel catch data, the Chlorophyll-a data and SST from MODIS satellite from June to August 2015. The results of this study showed that the distribution of Mackerel catch from June to August more were caught in August a total of 62.2 tons for 19 trips. While the chlorophyll-a between June and August ranged from 0.30 to 8.04 mg/m3 and SST in June-August ranged from 24.6 °C - 28.4 °C. The correlation between chlorophyll-a and Mackerel catch results showed very strong correlation (correlation coefficient (r) 0.934). While the correlation between SST with the Mackerel catch showed a strong correlation (correlation coefficient (r) 0.664).

The evolution of an extreme positive Indian Ocean Dipole (pIOD) that took place in the tropical Indian Ocean during the late boreal summer to early winter of 2019 is examined in terms of coupled ocean–atmosphere dynamics. The patterns of anomalous sea-surface temperature (SST) revealed a typical pIOD characteristic: cooling (warming) in the southeastern (western) tropical Indian Ocean. Based on the Dipole Mode Index (DMI), the evolution of the event started in mid-July and gradually strengthened with an abrupt weakening in early September before coming to its peak in late October/early November. It quickly weakened in November, and then it terminated in mid-December. During the peak phase of the event, the SST anomaly in the southeastern (western) tropical Indian Ocean reached about −2 °C (+1 °C). The pattern of anomalous SST was followed by an anomalous pattern in precipitation, in which deficit precipitation was observed over the eastern Indian Ocean, particularly over the Indonesia region. Earlier study has shown that dry conditions associated with the pIOD event created a favorable condition for a forest-peat fire in southern Sumatra. The number of fire hotspots has increased significantly during the peak phase of the 2019 pIOD event. In addition, anomalously strong upwelling forced by strong southeasterly wind anomalies along the southern coast of Java and Sumatra had induced a surface chlorophyll-a (Chl-a) bloom in this region. High surface Chl-a concentration was collocated with the negative SST anomalies observed off the southwest Sumatra coast and south Java. [ABSTRACT FROM AUTHOR]

Indonesia is the second largest producer of red algae in the world with one of the major Kappaphycyus. alvarezii farming areas is in Spermonde Islands, Pangkep Regency, South Sulawesi Province. K. alvarezii production in Pangkep Regency increased every year. However, the availability of natural seaweed can be threatened along with the increasing demand so that seaweed cultivation is necessary. Proper site selection is crucial to guarantee the success of the seaweed farming development. A Geographic Information system (GIS) with geospatial modeling approach was applied for identification of the site selection for K. alvarezii cultivation at the Liukang Tuppabiring District, Spermonde Islands by combining various physical and chemical parameters obtained from in-situ data and hydrodynamics modeling. The parameters are Sea Surface Temperature, salinity, pH, substrate type, current speed, wave height, DO, nitrate, phosphate, and Total Suspended Solid. This research also include the accessibility and the restricted area of shipping lanes for determining the area suitability of K. alvarezii cultivation. This research demonstrates a Geographic Information system with the cell-based geospatial modeling can be effectively used and found the the suitable categorized area for K. alvarezii is 4,546.28 ha, which is the combination of the suitable area of 4,463.08 ha and highly suitable criteria with an area of 83.2 ha. The potential productivity of wet-weight seaweed can reach 56,825 tons per cycle or 113,650 tons per year. This result suggests the GIS with geospatial modeling approach for developing the area of K. alvarezii culture can be applied in other area. [ABSTRACT FROM AUTHOR]

The phylogenetic data of the Java eel population is crucial for future catadromous aquaculture in Indonesia. The study aims to know how eel species from Java and West India differ in their evolutionary patterns. Four river estuaries in Central Java and one estuary in West Java, Indonesia, were chosen as samples of Javanese eel origins. Phylogenic comparison data from five regions of the Western Indian Ocean and one region of the Philippines (Pacific Ocean) were examined, taken from GenBank® data. The results showed that BLAST from 25 eels from Central and West Java was Anguilla bicolor bicolor (homology value 96 - 100%). The phylogenetic tree revealed that samples from Java nested into the West Indian Ocean with two Clades but were isolated from the Pacific Ocean eels. There are 25 pairs of monophyletic samples estimated to be the most recent common ancestor among the Indian Ocean eel samples from west to west, east to east, and west to east. [ABSTRACT FROM AUTHOR]

The Java Sea acts as a carbon source that contributes to the release of carbon dioxide into the atmosphere. The blue carbon ecosystems in the Karimunjawa Islands may absorb and store the carbon released from the Java Sea. The carbon stock in Kemujan Island (Karimunjawa Islands), one of these blue carbon ecosystems, was previously estimated using a remote sensing approach. In the present study, we investigated the carbon stock in the seagrass bed at Kemujan Island by conducting field observations and laboratory analysis. The result shows that there are only two seagrass species in the study area--'Enhalus acoroides' and 'Thalassia hemprichii'--which are categorized as nearly dense and very dense, respectively. Regarding the carbon biomass, the carbon stock below the substrate is more than that above the substrate. However, the carbon stock in the seagrass biomass is less than in the sediment. The average carbon stock in the seagrass bed at Kemujan Island is 4901.91 g C/m2, which is much more than the amount estimated by means of remote sensing. Furthermore, this amount is much larger compared with the average carbon stock of other areas in the Karimunjawa Islands. The large amount of carbon stock stored in the seagrass bed at Kemujan Island denotes the role of this seagrass bed as a carbon sink area. [ABSTRACT FROM AUTHOR]

Marine heatwave (MHW) is an extreme phenomenon of warm sea surface temperature anomaly that has a destructive impact on the marine ecosystem and organisms. This phenomenon increases every year in duration, frequency, and area due to the global warming. Almost all of the world's oceans have experienced MHW, including in the seas of the southern Java-Nusa Tenggara. The lack of detailed research in this area motivated us to analyze MHW drivers. MHW was identified with the 99th percentile method and duration of = 5 days as a threshold by using blended product of SST data. In 2013, an MHW event was identified in the seas of the southern Java-Nusa Tenggara. This MHW lasts for 37 days, from 8 June to 14 July. The maximum (mean) intensity of sea surface temperature anomaly reaches 2.60°C (1.83°C) above climatology with an average area of 36.53 × 104 km². Locally, we found that probably the positive downward shortwave radiation affected this anomaly. Furthermore, a remote process of the propagation of downwelling Kelvin wave during negative Indian Ocean Dipole may also affect this anomaly. The strong westerly wind along the equatorial Indian ocean forms downwelling Kelvin wave that propagates to the southern Java-Nusa Tenggara increasing SST in this area. [ABSTRACT FROM AUTHOR]