IMPACT OF THE PANDEMIC COVID-19 TO THE INDONESIA SEAS

This paper presents the effect of the COVID-19 pandemic on the Indonesian seas from April to October 2020. Data were mainly obtained through literature studies focusing on coastal and ecosystem services, noise observation in the ocean, and in-situ data for atmospheric conditions. The results of this study found that the pandemic has given the oceans and ecosystems time to recover from anthropogenic stresses even though the tourism and fisheries sectors have experienced strong economic shocks. A decrease in the amount of pollution in several major cities in Indonesia was also found during the pandemic period.

Moored Observations of Currents and Water Mass Properties between Talaud and Halmahera Islands at the Entrance of the Indonesian Seas

The currents and water mass properties at the Pacific entrance of the Indonesian seas are studied using measurements of three subsurface moorings deployed between the Talaud and Halmahera Islands. The moored current meter data show northeastward mean currents toward the Pacific Ocean in the upper 400 m during the nearly 2-yr mooring period, with the maximum velocity in the northern part of the channel. The mean transport between 60- and 300-m depths is estimated to be 10.1–13.2 Sv (1 Sv ≡ 106 m3 s−1) during 2016–17, when all three moorings have measurements. The variability of the along-channel velocity is dominated by low-frequency signals (periods > 150 days), with northeastward variations in boreal winter and southwestward variations in summer in the superposition of the annual and semiannual harmonics. The current variations evidence the seasonal movement of the Mindanao Current retroflection, which is supported by satellite sea level and ocean color data, showing a cyclonic intrusion into the northern Maluku Sea in boreal winter whereas a leaping path occurs north of the Talaud Islands in summer. During Apri–July, the moored CTDs near 200 m show southwestward currents carrying the salty South Pacific Tropical Water into the Maluku Sea.

Modeling small-pelagic fish biomass in the Indonesian seas: climate variability and climate change impacts

The present study uses the Community Earth System Model, version 1– Biogeochemistry [CESM1(BGC)] to examine the influence of climate variability and climate change on small pelagic fish biomass in the Indonesian seas. The fish biomass was calculated based on a fish production model according to primary production and energy transfer at the tropic level. The primary production data were obtained from results of CESM1(BGC) model from 1850 to 2015. Empirical orthogonal function (EOF) analysis of the calculated fish biomass identifies three regions in the Indonesian seas that are associated with coastal upwelling. These regions are located in (1) southern coast of Central Java Province until west-coast of West Sumatra Province, (2) southern coast of Central Java Province until the southern coast of Bali Province, and (3) Banda-Arafura Seas. Fish production variability in these regions exhibits semi-annual, annual, and IOD-ENSO related signals. Climate change impact for RCP 4.5 scenario produces ‘fish stock increase status’ in 2025 for the three regions, while the ‘fish stock current status’ will reoccur in 2050, except for the western part of Sumatra (part of region-1) which alters to ‘fish stock decrease status’.

Exploring bioactive pigments from marine bacterial isolate from the Indonesian seas

Marine microbes offer a significant source for biodiscovery due to their rich biodiversity and genetic capacity. Particularly, microbial pigments of marine origin are getting more attention in current research due to their widely perceived application as natural food colorants, antioxidant, antimicrobial, and many more. In the past five years, our research group has successfully characterised various bioactive pigments isolated from marine bacteria, including Erythrobacter flavus strain KJ5 that produces unique sulphur-containing carotenoids, Pseudoalteromonas rubra strain PS1 and SB14 that contain antimicrobial prodiginine, and Seonamhaeicola algicola strain CCI for high content of zeaxanthin. This paper describes the challenges we encountered in conducting research in exploring bioactive pigments especially with focus on carotenoid research, reviewed critically on strategy we developed for isolation of isolate as well as identification and elucidation of the pigments, and consideration for future research.

Dissolved oxygen variability of Indonesian seas over decades as detected by satellite remote sensing

The dissolved oxygen (DO) decrease in the ocean is a notable issue because of its potential impacts on marine biogeochemical cycles and ecosystem services. Satellite remote sensing application to support in-situ measurement is a time and cost-saving on wide scales DO monitoring. This study aims to determine the DO variability from 1993 to 2020, identify the potential areas to experience deoxygenation, and investigate the correlation between DO and other ocean parameters in Indonesian seas. The validation between in-situ and satellite-derived DO shows the determination coefficient of 0.73, indicating the satellite dataset reliability for the entire analysis. The multiple regression analysis among the long-term satellite-derived ocean parameters shows that the in-situ DO can be estimated by the combination of the potential temperature, total chlorophyll-a, and salinity. The potential temperature was statistically identified as the parameter with the highest correlation and influence on DO. The results of DO variability analysis show the overall decreasing trend with significant decreases in 1998, 2010, and 2016. There is a distinct difference in DO’s seasonal patterns in the southwestern and northeastern regions. The potential of ocean deoxygenation is detected in western Sumatra waters and the Arafura Sea at the 200–1,000 meters depth.

Population structure of Indian scad fish (Decapterus russelli) that was landed at the Nusantara Fishing Port of Ternate, North Maluku, Indonesia

Indian scad fish (Decapterus russelli) is a small pelagic fish species commonly caught in Indonesian seas. Excessive fishing efforts can cause population degradation, so it is necessary to understand its population structure. The purpose of this study was to analyze the population structure parameters of Indian scad fish, including growth parameters, cohort, and mortality. Sampling was done by Stratified Random Sampling method. Data analysis used the FISAT II application. Study results showed that there were 4 cohorts. The growth parameters of Indian scad fish obtained asymptote length (L∞) of 296.15 mm, coefficient of growth rate (K) of 0.60 per year, and initial age (t0) of -0.66 years. Value of coefficient of growth rate (K) indicated that growth of scad was relatively slow. The total mortality value (Z) was 0.51 per year, natural mortality (M) was 0.0034 per year, and fishing mortality (F) was 0.51 per year. So that the highest Indian scad fish mortality was caused by fishing mortality. The exploitation rate (E) was 1 per year, indicating that the Indian scad fish resources have been overexploited.

The distribution of benthic amphipod crustaceans in Indonesian seas

Amphipod crustaceans are an essential component of tropical marine biodiversity. However, their distribution and biogeography have not been analysed in one of the world’s largest tropical countries nested in the Coral Triangle, Indonesia. We collected and identified amphipod crustaceans from eight sites in Indonesian waters and combined the results with data from 32 additional sites in the literature. We analysed the geographic distribution of 147 benthic amphipod crustaceans using cluster analysis and the ‘Bioregions Infomaps’ neural network method of biogeographic discrimination. We found five groups of benthic amphipod crustaceans which show relationships with sampling methods, depth, and substrata. Neural network biogeographic analysis indicated there was only one biogeographic region that matched with the global amphipod regions and marine biogeographic realms defined for all marine taxa. There was no support for Wallaces or other lines being marine biogeographic boundaries in the region. Species richness was lower than expected considering the region is within the Coral Triangle. We hypothesise that this low richness might be due to the intense fish predation which may have limited amphipod diversification. The results indicated that habitat rather than biogeography determines amphipod distribution in Indonesia. Therefore, future research needs to sample more habitats, and consider habitat in conservation planning.

Extraction and Characterization of Collagen from Sand Sea Cucumber (Holothuria scabra)

Sand sea cucumber (Holothuria scabra) is an aquatic product that belongs to Echinodermata, a habitant in almost all Indonesian seas. The main component of the sea cucumber is protein, one of which is collagen. This study aimed to extract and characterize collagen from the species using the acid-base extraction method. The characterization of sea cucumber collagen includes molecular weight, amino acid components, Fourier transform infrared spectrophotometry, and scanning electron microscopy analysis. This study has successfully extracted collagen from the sample using an extraction system: NaOH 0.1 M; CH3COOH 0.1 M; and distilled water under 45°C treatments, gave 6% yield. The collagen has a molecular weight 110-130 kDa. Based on the infrared spectra, the specific functional groups of the collagen are amide A (3379.29 cm-1), amide B (2924.09 cm-1), amide I (1681.93 cm-1), amide II (1560.41 cm-1), and amide III (1249.87 cm-1). The collagen falls into type I. We suggest an alternative resource of collagen from sand sea cucumber, other than poultry and mammals. Keywords: characterization, collagen, extraction, fishery, sand sea cucumber