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The Variability of Surface Chlorophyll-a in Lake Rawa Pening within Five-Month Observations

100%

Amelia K. , Nuringtyas S. B. , Setiawan R. Y. , Setyobudi E. , Adharini R. I. , Aryudiawan C. , Maslukah L.

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tom Vol. 23, iss. 4

173--178

EN

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.

2

The Chlorophyll-a Response of Phytoplankton to Ratio N/P in Different Coastal Waters

88%

Maslukah L. , Handoyo G. , Wulandari S. Y. , Sihite C. B. , Sarjito

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tom Vol. 24, iss. 9

121--129

EN

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.

3

Variability of chlorophyll-a and diatoms in the frontal ecosystem of Indian Ocean sector of the Southern Ocean

88%

Kanta M. R. , Babula J. , Anilkumar N. P. , Krishna N. R. , Bhaskar P. V. , Soares M. A.

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nr 3

4

Impact of a dipole on the phytoplankton community in a semi-enclosed basin of the southern Gulf of California, Mexico

75%

Durán-Campos E. , Monreal-Gómez M. A. , Salas de León D. A. , Coria-Monter E.

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tom No. 61 (3)

331--340

EN

The present study assesses the impact of a dipole on the abundance and distribution of phytoplankton groups as well as the chlorophyll-a concentration in the Bay of La Paz, Gulf of California, Mexico. Based on in situ observations obtained in a multidisciplinary research cruise during the summer of 2008, a mesoscale dipole (cyclone-anticyclone) was observed; the cyclone had ~25 km diameter and tangential speed of ~45 cm s-1, while the anticyclone had ~15 km diameter and tangential speed of ~40 cm s-1. Strong gradients in conservative temperature and density were observed between both structures, suggesting the presence of an oceanic thermohaline front. Differences in phytoplankton distribution showed minimum abundance of diatoms in the southern bay and close to Roca Partida Island, and maximum in the periphery in the northern cold core. The maximum abundance of dinoflagellates and silicoflagellates occurred at the frontal zone. The chlorophyll-a concentration was high in the region associated with the frontal zone. Although mesoscale eddies are ubiquitous processes in the Bay of La Paz, this study represents the first observational report of the impacts of a dipole on the phytoplankton structure and chlorophyll-a in the region. The observations presented here indicate the existence of a strong association between the mesoscale processes and the phytoplankton community in the study area. This study highlights the value of efforts to improve projections of physical forcing and its influence on the planktonic ecosystem.

5

Inconsistent response of biophysical characteristics in the western Bay of Bengal associated with positive Indian Ocean dipole

75%

Seelanki V. , Nigam T. , Pant V.

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2022

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tom No. 64 (4)

595--614

EN

The Bay of Bengal (BoB) is known to have high primary productivity at its western margin during the Indian summer monsoon season (June–September). This higher coastal productivity is mainly caused due to the near-surface nutrient availability maintained by the local coastal upwelling process. The surface winds in the Indian Ocean significantly vary during El-Niño/La-Niña and Indian Ocean dipole (IOD). The current study examines the sea surface temperature (SST) and Chlorophyll-a (Chl-a) anomalies in the western BoB for the period of 18 years (2000 to 2017), using a coupled regional ocean biophysical model. All considered positive IOD (pIOD) years show discrete behavior of biophysical features in the western BoB. The co-occurrence years of pIOD and El-Niño modes are associated with contrast biophysical anomalies. In the analyzed pIOD events, the years 2006 and 2012 show an enhancement in the Chl-a anomalies whereas, the other two years (2015 and 2017) experience Chl-a decrement. The western BoB was anomalously warmer during the 2015 and 2017 pIOD years compared to the other two pIOD years (2006, 2012). This inconsistent response of biophysical features associated with pIOD years is investigated in terms of local surface flux (momentum, heat, and freshwater) changes over the western BoB. The combined impact of local surface flux changes during the individual years remains the major contributing factor affecting the upper-ocean stratification. Ultimately, the stratification changes are responsible for the observed inconsistent response of biophysical features by significantly altering the upper-ocean mixing, upwelling, and nutrient availability in the western BoB.

6

Strong Negative Indian Ocean Dipole Phenomenon in 2016 Reduce the Upwelling Intensity along the Seas of Southern Java

75%

Undap M. W. B. W. , Suryoputro A. A. D. , Wirasatriya A.

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tom Vol. 24, iss. 9

84--95

EN

The seas of Southern Java are located at the eastern equatorial Indian Ocean and therefore, they are strongly influenced by the Indian Ocean Dipole (IOD). Strong negative IOD occurred in 2016. However, none of the previous studies investigated its effect on the seas of Southern Java. This study aims to reveal the influence of the strong negative IOD in 2016 on the upwelling intensity along the seas of Southern Java as represented by surface temperature and chlorophyll-a. This research was conducted using satellite-based data and the analysis was based on climatology, and anomaly for 15 years (2007–2021). The data used includes sea surface temperature (OISST), wind (ASCAT), IOD index (DMI), chlorophyll-a (OC-CCI), and sea level anomaly (altimetry). The findings show that the strong negative IOD in 2016 had a significant impact on sea surface temperatures which made these waters warmer. The most visible impact is through the sea surface temperature anomaly map where in 2016 throughout the year it experienced a positive anomaly with a value of 2°C higher than the climatological average. The value of chlorophyll-a in these waters has also dropped drastically which, when viewed from the anomaly map, has a value of 0.2 mg/m3 lower than the climatological average, especially during the upwelling month. This means that, strong negative IOD in 2016 reduced the upwelling intensity along the seas of Southern Java. We also found the propagation of downwelling Kelvin waves from the Indian Ocean to the Southern Java waters which bring warm temperatures and cause downwelling events during the strong negative IOD in 2016 that hampers coastal upwelling along the seas of Southern Java.

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Fractionation and bioavailability of phosphorus and its relation to chlorophyll-a at the coastal area of Semarang city

63%

Maslukah L. , Wirasatriya A. , Widada S. , Ismunarti D. H. , Yusuf M. , Salma U. , Zainuri M.

Ecological Chemistry and Engineering. S

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2022

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tom Vol. 29, nr 2

183--197

EN

We investigate the distribution of various fractions phosphorus (P) in sediments at the coastal area of Semarang City. Samples were collected from thirteen locations at the Banjir Kanal Barat, port and Banjir Kanal Timur. Sedimentary parameters such as sand, silt, clay, and organic carbon were analysed in order to find out their relation with various P fractions. The sediment types are predominantly sandy and silty with low clay content. Among all fractions (loosely bound/Ads-P), bound calcium/Ca-P), iron bound/Fe-P), and organic fraction/OP), Ca-P fractions constitute the largest portion (71.2 %) followed by iron-bound (17.0 %), organic fraction (10.4 %) and loosely bound (1.4 %). The bioavailable P fractions range from 20.2 % to 42.0 % of the total P (TP) content with average 28.8 %. Relatively high Ads-P content is observed in offshore locations with comparatively high mud percentage as compared with the near-shore locations. The order of abundance of the main forms of P in the Semarang coastal surface sediments is as follows: Ca-P > Fe-P > OP > Ads-P. The concentration of this fraction causes the abundance of chlorophyll-a from 9.09 to 21.09 mg/m3.

8

Ocena możliwości zastosowania teledetekcyjnych metod pomiaru eutrofizacji śródlądowych zbiorników wodnych

63%

Pierzchała Ł.

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tom Vol. 21, nr 4

27--32

PL

Rozwój satelitarnych technologii obserwacji powierzchni ziemi stwarza możliwości wdrożenia nowoczesnych narzędzi monitoringu jakości wód powierzchniowych. W niniejszym artkule zaprezentowano wyniki badań, których celem było opracowanie zautomatyzowanej metody pomiaru eutrofizacji wód śródlądowych. Przeanalizowano zalety i ograniczenia przedmiotowej technologii oraz oceniono potencjalne możliwości jej wykorzystania. Podstawowym wskaźnikiem stanu troficznego wód powierzchniowych jest koncentracja chlorofilu-a w wodzie. W ramach przeprowadzonych badań uzyskano silny związek pomiędzy wartościami koncentracji chlorofilu-a określonych na podstawie standardowych metod pomiarowych, a wartościami tego parametru obliczonymi na podstawie satelitarnych danych spektralnych. Przedstawiono także funkcjonalności opracowanego oprogramowania pozwalającego na automatyczny pomiaru eutrofizacji wód śródlądowych za pomocą teledetekcji. Pomimo szeregu ograniczeń technologii, wykazano wysoki potencjał aplikacyjny przedmiotowego rozwiązania.

EN

The development of satellite technologies for observing the earth’s surface creates the possibility of implementing modern tools for surface waters quality monitoring. This article presents the results of the research aimed at developing an automated method for assessment of the eutrophication of inland waters. The advantages and limitations of the technology were analyzed and the potential possibilities of its application were described. The basic indicator of the trophic state of surface waters is the concentration of chlorophyll-a in the water. As result of the research, a strong relationship was obtained between the chlorophyll-a concentration values determined on the basis of standard measurement methods, and the chlorophyll-a values calculated on the basis of satellite spectral data. The functionalities of the developed software for automated measuring eutrophication of inland water using temote sensing were also presented. Despite a number of limitations of the technology, high application potential of the solution has been demonstrated.