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The plastic debris that breaks down smaller than 5 mm is defined as microplastics and the source of these microplastics can come from daily products used like laundry activities. Bogowonto River is a vital component of the aquatic ecosystem that provides water for domestic, agricultural, and industrial needs. This study aimed to determine the abundance and characteristics of microplastics in Bogowonto River. Sampling was conducted in December 2023, totaling 15 water samples and 15 sediment samples with 3 repetitions at 5 stations. Determination of the location point using purposive sampling method in which the sampling station was selected by considering anthropogenic activities. Water sampling was carried out using a plankton net and subsequent destruction of organic matter and filtration. A grab sampler (Van Veen, Hydro-Bios, Germany) was used to take sediment samples, which were then separated by density, and filtered. MP abundance in water samples ranged from 126.67 ± 11.55 to 253.33 ± 64.29 MPs/m³ (... ± SD) and sediment samples ranged from 100.00 ± 45.83 to 236.67 ± 126.62 MPs/kg (... ± SD). The shape of microplastic fiber is the most dominant in the sample, while the red and blue colors are the most dominant colors and consistently appear in all samples. Testing to determine the type of polymer in the sample using the FTIR-ATR method. Polyamide and polypropylene are the two most dominant types of polymers. Waste discharges from the agricultural, construction, hospital, tourism, market, and residential sectors all contribute to microplastic pollution of the river. The meander pattern of the river between stations 3 and 4 has an impact on the transportation of microplastics, which affects their abundance. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the dynamics driving seasonal and interannual surface chlorophyll-a (chl-a) variability in the Karimata Strait (KS). The analysis shows that high chl-a concentrations were observed in the KS during December – February (northwest monsoon season) extending northwestward along the eastern coast of Peninsular Malaysia and northeastward along the northern coast of Borneo Island. This high chl-a concentration contrasts with the low chl-a concentration observed along the southern coast of Sumatra and Java during the same season. A substantial upwelling signal was identified in the central-eastern section of the South China Sea and along the northern coast of Java and the eastern coast of Sumatra from December to February. The positive wind stress curl forced downwelling in the southern section of the KS and the northern half of the Java Sea off the coast of Kalimantan. The elevated chl-a concentration in the KS during the northwest monsoon season could not be attributed to wind dynamics alone. The increase in surface chl-a concentration during the northwest monsoon season was associated with an increase in allochthonous nutrients from river discharges caused by increased precipitation over land. On an interannual timescale, a high chl-a concentration was observed during the southeast monsoon season when the La Niña event occurred in the tropical Pacific. The warm SST, associated with favourable downwelling winds, was observed over the entire the KS. It is suggested that anomalous chl-a that bloomed during the La Niña event was associated with anomalously high precipitation over land that transported nutrients to KS through river discharge. [ABSTRACT FROM AUTHOR]

The purpose of this study is to determine the effect of the escape gap of cylinder folding trap on catch per unit effort (CPUE), trap rate, composition, and size of fish caught in the coastal waters of Tuban Regency. The research was conducted in November 2019 by deploying 60 units in ten experimental fishing trips at different locations. The traps were 20 units without escape gap, 20 units with an escape gap of 3 cm x 6 cm, and 20 units with an escape gap of 4 cm x 7 cm. Overall, the experiments resulted in a collection of 22 species of marine organisms, such as swimming crabs (33% of total weight), snails, shrimps, crabs, fishes (55% of total weight), and cuttlefish. The highest CPUE was found for the traps with escape gaps of 4 cm x 7 cm, i.e., 9.18 gr/trap/trip. There was no significant difference in the total catch, the weight of catches, trap rate, and catch per unit effort (CPUE) among the three types of traps.

This study aimed to determine the composition and catch rate of folded cube fish pots in the seawater of the Tuban Regency. The research was conducted in December 2018 located in the Sokorejo, Tuban Regency, using 30 units of folded cube fish pots with a size of 50x50x50 cm2. The cube folded trap installation was done in 10 times of catch trip and installed in the morning. The catches were collected, identified, and measured for their individual length and weight. The crabs were measured for the length and width of their carapace. The catching result of folded cube fish pots was classified into five types which are fish group (48.97%), crabs group (29.59 %), swimmer crabs (7.1%), Land hermit crab (6.12%), and mud snails (8.16%). The result showed that Two-spined Arm Swimming Crab (Charybdis anisodon) was the most dominant type of catch equal to 29.59% of the total catch, while other types of catch that were quite common are Pig Faced Leather Jacket (Paramonacanthus choirocephalus) (9.18%), and Crescent Pearch (Terapon jarbua) (8.16%). The average catch rate for folding cube was 32%/trip with a weighted average catch of 436.58 gr/trip.

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]

Lake Rawa Pening is a natural lake in the Semarang Regency of Central Java Province, Indonesia, and its existence is pivotal to the surrounding communities as it provides ecological, economic, and social benefits. The ecosystem health of Rawa Pening can be represented by chlorophyll-a concentration because it indicates phytoplankton biomass, nutrient availability, and fish resources. Hence, the present study aims to disentangle the monthly variability of surface chlorophyll-a in Rawa Pening Lake by analyzing water samples that were collected once a month from nine stations within five-month observations (September 2020 to January 2021). The samples were analyzed using spectrophotometric method. Results showed that the highest surface chlorophyll-a concentration (23.33 mg/m3) took place in December, while the lowest concentration (12.64 mg/m3) occurred in October. The monthly variability of surface chlorophyll-a was likely controlled by variation of rainfall, with the highest (18.72 mm) and the lowest (12.33 mm) rainfall happened in December and October, respectively. The present study also indicates the anthropogenic activities such as agricultural activities, floating food stands, aquaculture, and tourist boats may contribute to surface chlorophyll-a variability in Rawa Pening Lake. [ABSTRACT FROM AUTHOR]

The investigation of spatial changes in phytoplankton biomass and turbidity provide essential information for the survival of the coral reef ecosystem. The phytoplankton biomass variations are driven by many factors, such as nutrient inputs from anthropogenic and natural. In turn, turbidity is determined by sediment resuspension or transport from terrestrial systems. The estimation of phytoplankton biomass is represented by the chlorophyll-a concentration. This study aimed to analyze the chlorophyll-a dynamics to water quality parameters, such as turbidity, suspended solids, dissolved oxygen, pH, salinity and temperature. The in-situ data gathered at 26 stations in the waters of the Barrang Caddi Island in August 2020. The results show that chlorophyll-a and turbidity have a negative correlation in the western and eastern regions, since turbidity inhibits the rate of photosynthesis and causes the decreasing of phytoplankton biomass. Nevertheless, the highest concentration of chlorophyll-a was found in the southern location, in small spots around islands and reefs, including near Barrang Caddi Island. Total Suspended Solid has more significant effect on chlorophyll-a than other water parameters, such as turbidity, temperature, salinity in the study area. [ABSTRACT FROM AUTHOR]

This study investigates the concentration of chlorophyll-a (chl-a) using the data of field observation and MODIS Aqua imagery. The field observation data were retrieved by using a conventional method and processed using spectrometric analysis. This study covers the coastal and near land areas which have different levels of anthropogenic activity. The results showed that the coastal waters of Semarang with a high level of anthropogenic activity persistently show a concentration of chlorophyll a (chl-a) twice as large as Jepara coastal waters. This comparison value is obtained based on imagery and field data. Meanwhile, the ratio of chl-a field data in each region shows a value of ±5 times greater than the MODIS data. Field observation data shows a higher value than the MODIS Aqua imagery data. The use of imagery data can be employed as a method of monitoring the eutrophication process on the coast. On the basis of the chlorophyll a classification and field observations, the coastal water of Semarang are classified as eutropic waters and Jepara is categorized as mesotropic category. The classification results will be different if monitoring is carried out using the image data with a location far from the mainland, the Semarang waters are included in the mesotropic category (> 2 mg·m-3) and Jepara is included in the oli gotropic water category (< 2 mg·m-3). [ABSTRACT FROM AUTHOR]