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The real-time monitoring of ocean wave data is a crucial element in marine environmental monitoring and the development of marine resources. It is unfortunate that the majority of wave measurement devices remain challenging, relatively high-priced, and require sophisticated technology. This study investigates the validation of a new type of ocean wave measurement, designed based on the mini wave gauge (MWG), using low-cost materials. The study utilizes an accelerometer sensor, specifically the ADXL335, which is converted to measure wave height, and the GY-271 designed to measure wave direction. This research addresses the validation of MWG by comparing measurements from the acoustic doppler current profiler (ADCP) and HOBO. The validation of wave height demonstrates high accuracy, with a MAPE percentage of 0.46% between MWG and ADCP, and 23.30% between MWG and HOBO. In contrast, the validation of MWG for wave direction by ADCP still requires improvement, with a MAPE of 36.75%. This is due to the sensor's sensitivity to the earth's magnetic field, which requires further improvement of the buoy design to accommodate the direction of incoming waves. Additionally, the MWG's sampling rate in milliseconds allows for analyzing wave characteristics based on wave periods using the fast Fourier transform (FFT) method. [ABSTRACT FROM AUTHOR]

The waters that surround the Indonesian archipelago are home to some of the most fruitful primary resources that can be found anywhere in the southeastern Indian Ocean. In this work, an investigation of seasonal fluctuations in nutrient content within the region, utilizing 30-years reanalysis data generated by Copernicus Marine Service, was presented. The month of September, October, November (SON) exhibits the maximum concentration of nitrate content, primarily observed in the southern region of Java and the Lombok Strait. The concentrations of nitrates experience significant changes that are notably impacted by Indian Ocean Dipole (IOD) occurrences. Specifically, a positive IOD event is associated with elevated nitrate levels, particularly during the period spanning from June to December. Furthermore, in the southern Java region, an inverse correlation was identified between nitrate concentrations and surface zonal currents, commonly referred to as the South Java Current (SJC). Concurrently, the reinforcement of the Indonesian Throughflow (ITF) in the Lombok Strait is consistently accompanied by an elevation in nitrate concentration within the southern region. [ABSTRACT FROM AUTHOR]

Phytoplankton growth is influenced by the presence of nutrients N (nitrogen) and P (phosphor). Each region has a specific N/P ratio, due to the influence of anthropogenic inputs. This study aimed to assess the response of phytoplankton chlorophyll-a (Chl-a) biomass due to differences in N/P ratio by the influence of river flow in the north coast of Java; Jobokuto Bay (Jepara), the coastal waters of Semarang and the front of the Cisadane river. N-nutrients were analyzed in the form of N-NO3 (nitrate), and N-NH4+ (ammonium ions), and orthophosphate ions (P-PO42-). Nutrient analysis was spectrometric, using the reduction methods (nitrate), ammonium (indophenolblue), and phosphate (molybdenum-blue). Test for site differences using Kruskall-Wallis, followed by a posthoc test. The results showed that Semarang waters had a lower N/P (Stoichiometric) ratio than Jepara and Cisadane, which can be used to predict that P nutrient input is higher than N. This high P input impacts microalgal development (chlorophyll-a). In addition, we also found Semarang waters to have higher speciation of inorganic N in the form of ammonium, which is one of the drivers of eutrophication in these waters. The use of a ratio of N/P is very important in estimating the eutrophication process and can be used to estimate the dominance of nutrients entering the water due to anthropogenic activities in the upstream area. [ABSTRACT FROM AUTHOR]

Banjir Kanal Barat (BKB) and Banjir Kanal Timur (BKT) are widely used for various community activities such as residential areas, industry, fish cultivation, and auction. Community activity around BKB and BKT will affect N and P nutrient inputs, which further affects phytoplankton abundance. In this study, phytoplankton biomass was estimated through chlorophyll-a (chl-a) measurements. The purpose of this study was to determine the distribution of the chl-a and determine the influence of phosphate and nitrate in front of the estuary from BKB and BKT. Sampling was carried out at 8 stations from each estuary and was carried out in the dry season. The concentration of chl-a, phosphate, and nitrate is further described in the form of a distribution pattern based on the interpolation method with ArcGIS 10.2 software. The results showed that the average ± sd of chl-a, respectively was 15,781 ± 16.90 mg/m3 and 17,710 ± 15.31 mg/m3, phosphate was 0.0174 ± 0.0057 ppm and 0.0096 ± 0.0164 ppm, nitrate was 2.9086 ± 1.1824 ppm and 1.6919 ± 1.6316 ppm. The distribution pattern of chlorophyll-a and phosphate decreases in concentration towards the sea, while nitrate forms an irregular pattern and has a different pattern in each estuary. Nutrient phosphate has a positive correlation with chlorophyll-a. [ABSTRACT FROM AUTHOR]

The Kendal River estuary receives nutrient input from various community activities from the surrounding waters and will indirectly affect the physical and biological quality parameters of the waters. Phytoplankton biomass is a parameter of biological quality, which can be measured based on the concentration of chlorophyll-a, while suspended particulate matter (SPM) is a parameter of its physical quality. The purpose of this study was to determine the spatial distribution of nutrients and suspended particulate matter and their effect on chlorophyll-a in the Kendal River Estuary. This research was conducted in November 2017. Sampling was carried out at 12 stations representing river, coastal and high seas areas. Chlorophyll-a and nutrients N & P, were measured based on the spectrometric method and SPM using the gravimetric method. Spatial distribution of each parameter using kriging interpolation with ArcGIS. The results showed that chlorophyll-a, nitrate, phosphate, and SPM had a similar spatial distribution pattern, which was high in the estuary area and decreased in concentration towards the sea. The results of the multiple linear regression model analysis between chlorophyll-a on nutrients and SPM followed the formula [chl-a] = -11275 + 5.249 [NO3 -] + 6.987 [PO4 2-] + 0.004 [SPM], with a coefficient of determination (R2) of 0.76 . The most influential water quality is phosphate, followed by nitrate and SPM. Based on the chlorophyll-a value, Muara Kendal is categorized as eutrophic. [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]