South Java Research Articles

Seasonal variation of chlorophyll-a in South Java over the past quarter-century

Seasonal variation of chlorophyll-a in South Java over the past quarter-century

Impacts of the Madden‐Julian Oscillation on Marginal Sea Heatwaves of the Southeastern Tropical Indian Ocean

AbstractMarginal seas of the southeastern tropical Indian Ocean (SETIO), including the South Java coasts and the Timor and Arafura Seas, are hotspots of large‐scale marine heatwaves (MHWs) in austral summer with notable impacts on local ecosystems. Yet, the prediction of these MHWs remains challenging. By analyzing 39 MHWs and 45 marine cold‐spells (MCSs) observed in the summers of 1982–2021, this study reveals a robust modulation effect of the Madden‐Julian Oscillation (MJO) on these events. The results show that 56% of MHWs and 51% of MCSs overlapped with MJO events, and their duration is systematically longer than others. Moreover, MHWs in phases 3–4 and MCSs in phases 6–7 of the real‐time multivariate MJO (RMM) index were nearly 2–3 times stronger in intensity than the others. The passage of MJOs drives prominent intraseasonal sea surface temperature (SST) variability in the SETIO through perturbing surface heat fluxes, which in turn modulates the occurrence of MHWs and MCSs. During RMM phases 1–2 (convective center over of the east of Africa or the central‐western Indian Ocean), the SETIO is controlled by a dry condition, with increased surface insolation and suppressed latent heat release. These anomalous fluxes drive a persistent SST increase, facilitating the emergence of strong and prolonged MHWs in the subsequent RMM phases 3–4. Further analysis suggests an 18% probability for MHWs in the SETIO 12 ± 10 days after Phase 1. Therefore, the MJO contributes to the predictability of MHWs/MCSs of the SETIO, with implications for predicting climate extremes and hazards.

New records of Cryptoblepharus cursor Barbour, 1911 (Squamata, Scincidae, Eugongylinae) from Java, Indonesia

he Lombok Snake-eyed Skink, Cryptoblepharus cursor Barbour, 1911 has been recorded in South Java prior to 1940. However, information on its population on the island are scarce. This study presents new records of C. cursor from Java. Visual Encounter Survey were conducted to observe habitat selections and collect skinks as voucher specimens. South Javan C. cursor are restricted to sandy littoral zones with Ipomoea pescaprae (L.) R.Br. – Spinifex littoreus (Burm.f.) Merr. whereas Lombok C. cursor are saxicolous, preferring rocky coasts. They also differ from the scansorial C. balinensis Barbour, 1911, a sympatric congener from Java.

Need Assessment for Coastal Tourism Area in the Face of Tsunami Risk: The Case of Pangandaran

As the fourth world's longest coastline, coastal tourism has become a significant component of Indonesia’s economy. Approximately 57% of this coastline is prone to the deadliest coastal hazard, i.e., tsunami. The progressive development of the tourism industry has created a massive increase in built infrastructure, hotels, roads, electrical and water distribution systems, and an increased number of people, including tourists and tourism workers, in rural coastal tourism areas. Due to the tsunami threat, rural coastal tourism regions' economic and social development faces enormous potential losses in lives and infrastructure and disruption of economic activity, especially for small and medium business enterprises. However, this coastal tourism industry has failed to engage in proper disaster risk reduction strategy and tourism business resilient building in most tourist destination regions in Indonesia. To address these complex problems, this study explores the adaptation of the concept of Business Continuity Plan of a single enterprise to upscale to an area or zone, i.e., the Area Business Continuity Planning, to enhance the holistic disaster-resilient tourism industry in Indonesia, with Pangandaran as the study location. As a newly formed regency, Pangadaran is an emerging super-destination tourism area designated by national and provincial governments. This region experienced a devastating tsunami in 2006, and even today, its coastal communities live under the threat of tsunamis that South Java Megathrust can generate. Based on an in-depth and holistic study, this study finds the Pangandaran coastal tourism resilience level, recognizing critical stakeholders and identifying the collaborative BCP strategies in Pangandaran.

MENINGKATKAN KESADARAN WISATAWAN DALAM MENJAGA KELESTARIAN EKOSISITEM WISATA PANTAI BAHARI DI KECAMATAN JAWAI SELATAN

One of the tourist attractions that attracts the attention of domestic and foreign tourists is the marine beach in Kec. South Java. Looking at the history of this Marine Tourism Beach, it has been around for a long time, this beach is an empty beach and forest that is not managed or developed, since 2019 one of the residents of Jawai Laut Village has taken the initiative to invite local residents to explore this still beautiful beach and form an awareness group. Marine Tourism Beach tourism which has 52 members. The aim of this background is to increase tourist awareness in preserving the marine coastal tourism ecosystem in the Javai Laut village, Javai sub-district. The methods used in the activity include counseling and discussion. Based on outreach activities at the maritime coast of Jawai Laut Village, Kec. This outreach program conveys information regarding tourist awareness in preserving the marine coastal tourism ecosystem in Jawai Laut village, Jawai sub-district the tourists were very enthusiastic in taking part in the outreach that was carried out.

Pure Islamic rationalization of the Muhammadiyah congregation in the hills and south coast of Watulimo-Trenggalek

The diversity of people of the hills and the coast of South Java has a different style from the people of the coast of North Java. This research aims to explore how Muhammadiyah as a puritan Islamic organization can develop and grow during the culture and habits of the hill community as well as the South coast of Watulimo-Trenggalek, and how the social behavior of Muhammadiyah members and congregation of the Watulimo Branch. This study used a qualitative method with Max Weber’s social theory approach regarding changes in society to become modern which looks different between people in the East and West regions. The results showed the success of the Muhammadiyah movement in spreading its teachings in Watulimo using two approaches. The first is by the study route that has been adapted to the cultural context of the south coast community, and the second is by formal education. This study concludes that these two approaches led to the emergence of four Muhammadiyah jemaah groups in Watulimo.

Evaluating Wave Potential and Assessing the Economic Viability of Wave Energy Converters in the South Java Seas

As an archipelagic nation, Indonesia holds substantial potential for wave energy as a renewable resource. Certain coastlines of islands facing the Indian Ocean, particularly in the western and southern regions, exhibit significant wave energy throughout the year. To identify suitable locations for Wave Energy Converter (WEC) installation, it is essential to assess wave hindcast data. This study utilizes NOAA and ERA5 reanalysis wave data to analyze wave characteristics in Indonesia from 2008 to 2018. Data processing with Ocean Data View is employed to estimate key wave parameters at various locations, including significant wave height, mean wave period, and mean wave direction. Two locations in the South Java seas were identified for WEC installation based on this research. The average values for the period 2008 to 2018 indicate a significant wave height of around 2m, with a maximum height of 5m, a wave period of 10–14s, and a wave direction of 195–210 degrees. Notably, NOAA data suggests a higher estimation of significant wave height compared to ERA5 data. The average annual wave power potential based on ERA5 and NOAA is 164.43 MW/m and 252.15 MW/m, respectively. Furthermore, this study incorporates an economic simulation for the construction of a multi-point absorber WEC. The objective is to offer insights into the Levelized Cost of Electricity (LCOE) and compare it with other WEC technologies. Assuming a WEC capacity of 130 kW, the total construction cost is estimated at $2,093,725, resulting in a Levelized Cost of Energy (LCOE) of $91/MWh.

Influence of Anomalous Upwelling on the Water Mass of South Java during Two Positive Indian Ocean Dipole in 2015 and 2019

Upwelling is a phenomenon that often occurs in the ocean. Upwelling can be interpreted as the process of rising sea water masses from below the surface to the surface due to the vacancy of sea water masses at the surface. The upwelling phenomenon will cause many anomalies that have a direct impact on ocean dynamics, one of which is the dynamics that occur in the waters south of Java. The formation of the coastal upwelling phenomenon in the waters south of Java in 2015 and 2019 was the cause of the active Positive IOD in both years. By carrying out time series analysis and spatial data visualization processes as well as correlation methods to determine the relationship between parameters, this research aims to discuss and find out about the influence of coastal upwelling dynamics on the waters of southern Java in 2015 and 2019. The results obtained from this research show that the coastal upwelling phenomenon formed in 2015 and 2019 along the waters of southern Java resulted anomalies in dynamic patterns in the form of decreasing sea surface temperatures and increasing chlorophyll-a concentrations

First photograph record of the segura’s throatspine gudgeon Belobranchus segura Keith, Hadiaty & Lord 2012 in the south of Java, Indonesia (Teleostei: Gobiiformes: Eleotridae)

Segura’s Throatspine Gudgeon Belobranchus segura Keith, Hadiaty & Lord 2012 is an amphidromous fish from the Indo-Pacific region. In Indonesia, B. segura was distributed in Papua, Halmahera, Sulawesi (previously known as Celebes) and Java Island. The finding of this species in the lower stream river of Malang district, south of Java, Indonesia, was firstly recorded here. This study provides the photographs of a single male specimen of B. segura, the description of morphological features of a specimen and their habitat conditions.

Surface Deformation Assessment due to the Grindulu Fault Activities using Sentinel 1 Data by Applying the Small Baseline Subset (SBAS)-InSAR Technique

The location of Grindulu Fault is in the Pacitan Regency on the Southern Coast of Java, which directly faces the South Java Subduction zone. The activities of the fault could contribute to the surface deformation in the surrounding area. The Meteorology Climatology and Geophysics Council in Indonesia (BMKG) reported a 3.1 Mw earthquake on 7 November 2019, possibly related to the Grindulu fault activities. In this research, we assess the surface deformation around the Grindulu Fault using the Sentinel I data by applying the Small Baseline Subset (SBAS) - Interferometry Synthetic Aperture Radar (InSAR) technique. The SBAS-InSAR is one of the techniques that can provide spatial-temporal continuous analysis of the surface deformation over the extent of InSAR data. The SBAS algorithm was applied to twenty-three (23) ascending Sentinel-1B images to assess the surface deformation in Pacitan between 2019 and 2021 using the GMTSAR software. The results showed surface deformation dominated by subsidence over the whole area, except at the northern part of Grindulu Fault, with the mean velocity values ranging from -2.07 to -43.05 mm/yr.

Seasonal and Interannual Variability of Fronts and Their Impact on Chlorophyll-a in the Indonesian Seas

Abstract The spatiotemporal variability of oceanic fronts in the Indonesian seas was investigated using high-resolution satellite observations. The study aimed to understand the underlying mechanism driving these fronts and their impact on chlorophyll-a variability. A high value of frontal probability was found near the coasts of major islands, exhibiting a distinct seasonal cycle with peaks occurrences during austral winter. The distribution variability of chlorophyll-a was generally consistent with the presence of active frontal zones, although a significantly positive relationship between fronts and chlorophyll-a was limited to only some specific areas, e.g., south Java Island and the Celebes Sea. Wind-driven upwelling played a major role in front generation in the Java upwelling region and enhanced frontal activity can promote the growth of phytoplankton, leading to higher chlorophyll-a. Furthermore, the study demonstrated that wind patterns preceded variations in front probability and chlorophyll-a by approximately two months. This lag suggests that the spatiotemporal variability of fronts and chlorophyll-a in this region is primarily influenced by the monsoon system. In addition, the sea surface temperature (SST) simultaneously modulated the chlorophyll-a variability. Negative SST anomalies were typically associated with positive anomalies in front probability the chlorophyll-a in most areas. Notably, the interannual variability of fronts and chlorophyll-a are prominent in the Java upwelling region. During El Niño years, this region experienced an enhanced monsoon, resulting in a negative SST anomaly alongside positive anomalies in front probability and chlorophyll-a. A comprehensive description and underlying dynamics of frontal activity in the Indonesian seas are provided by this study. The findings are helpful to delineate the variability in chlorophyll-a, thereby facilitating the future understanding of local primary production and the carbon cycle. Significance Statement As typical mesoscale processes, oceanic fronts have significant impacts on biological processes and fisheries in marginal seas. The complex spatiotemporal variability of fronts and their effects on biological processes in the Indonesian seas remain poorly understood. This study aimed to address this knowledge gap by investigating the seasonal and interannual variability of fronts and their influence on chlorophyll-a, a key indicator of phytoplankton biomass and primary productivity. The study identified a high frontal probability in south Java Island during austral winter and El Niño years. Wind-driven upwelling was found to be a major factor in front generation and promoting phytoplankton growth. The findings of this study will improve the theoretical knowledge of regional dynamics, local primary production, and the carbon cycle in the Indonesian seas, benefiting fisheries management and ecosystem conservation efforts.

First record of red seabream, Pagrus major existence in the eastern Indian Ocean south of Java, Indonesia revealed by DNA barcoding

Abstract. Nuryanto A, Bhagawati D, Winarni ET, Rofiqoh AA. 2023. First record of red seabream, Pagrus major existence in the eastern Indian Ocean south of Java, Indonesia revealed by DNA barcoding. Biodiversitas 24: 6023-6030. The red seabream, Pagrus major, is widely believed to be mainly inhabited in the Northwest Pacific region. Although there are no previous studies reporting its existence in the Indian Ocean, a morphologically similar species of silver seabream, P. auratus, has been discovered. To comprehensively assess the geographical distribution of both species, there is a need to carry out a taxonomic study using DNA barcoding technique. Therefore, this study aimed to evaluate the taxonomic status of seabream (Sparidae) in the east Indian Ocean south of Java, Indonesia, using the cytochrome c oxidase 1 barcoding. Fish specimens were collected during the June to August 2023 field trips at fishing ports and auction centers along West Java and Banten southern coastlines. A total of 51 specimens were successfully barcoded and 99% genetic similarity was used as a species border. The results showed that three seabream species were identified, with intraspecific genetic similarity ranging from 99.77% to 100% and low genetic distance between 0.000 and 0.005 to one top hit conspecific. Furthermore, 21 specimens were identified as P. major with high genetic similarity ranging from 99.43% to 100% and genetic homology ranging from 99.44% to 100%. This discovery represented the first record of P. major in the east Indian Ocean, South Java, presenting essential data need for capture fisheries management in the region.

Spatial distribution and composition of marine litter on sandy beaches along the Indian Ocean coastline in the south Java region, Indonesia

Marine litter in coastal areas can bring economic, social, and environmental damage, especially the loss of aesthetic value of a tourist site. Therefore, research on the composition of marine litter to identify its sources is important for planning strategic action to minimize the problem. This study analyzed beach litter composition on five beaches (Kondangmerak, Balekambang, Ungapan, Ngudel, and Goa Cina) along the Indian Ocean coastline in the eastern part of the south Java region, Indonesia. All the beaches are known as the famous touristic beaches of Malang City, and receive many visitors, especially during the holiday season. Beach litter composition was obtained by collecting different types of litter in a 5 x 5 m square transect. Five square transects were placed along the beach strandline at each beach, and intervals of 20 m separated each transect. In each transect, the litter was collected and counted based on its category (plastic, paper, rubber, fabric, processed wood, metal, glass, ceramic, and hazardous items) and size (0.5–2.5cm, 2.5–5cm, 5–10 cm, and > 10 cm). There was a statistically significant variation in the number of litters among the sizes (p<0.05). However, the distribution of beach litter remained consistent across beaches regardless of its size. In general, beach litter with a size > 10 cm was found least on all beaches (< 15%), while the other three size categories were found in similar numbers (in the range of 20% to 50%). Plastic was the dominating type of litter on all beaches. Based on the Clean Coastal Index, all beaches were considered dirty to extremely dirty. All litter on the beaches was the product of tourism activities, and littering habits play a significant role as the source of marine litter in the study areas. Since this is the first study on the marine litter composition in the eastern part of south Java, the results of this study can be used as a baseline for future studies to prevent marine debris pollution and to develop management strategies for reducing the impact of marine debris on the environment.

Variability of the South Java Current from 1993 to 2021, and its relationship to ENSO and IOD events

Variability of the South Java Current from 1993 to 2021, and its relationship to ENSO and IOD events

Looking at the Local Participation of Coastal Communities in South Java, Indonesia

This study aims to describe the issues and problems of community participation related to the empowerment program entitled PKPT (Development of Strong Coastal Area) in the coastal areas. This study also discusses the importance of creating a participatory development model. This study is essential because PKPT implementation is specific, combining the top-down participation mechanism from the central government with the bottom-up mechanism, namely the northern coastal communities in South Java. The combination of the two mechanisms illustrates the complexity of issues and problems that are not simple because they involve the interests of the central government and the interests of ordinary citizens in coastal areas. Moreover, the focus of this study has yet to be widely studied by previous studies. This study uses a qualitative method applying an action research approach. The informants of the research are organizers of the coastal community, heads of village and village officials, and personnel of the Marine and Fisheries Service of Kebumen Regency in South Java. The result shows that implementing the PKPT program in coastal areas of Java, especially in Kebumen, uses both top-down and bottom-up mechanisms resulting in low participation of the community in the implementation of PKPT substantively. Thus, implicating the lack of sustainability in the empowerment program. This study presents a participatory development model that is expected to be a reference in organizing a sustainable empowerment program for the coastal areas in the future.

Challenges and Opportunities for Halal Tourism in Banyumas

The tourism sector is one of the sectors that has an important role in the Indonesian economy. Since the concept of halal tourism emerged in early 2010, various reactions have emerged to the development of halal tourism. This year, Indonesia won the title of Top Muslim Friendly Destination of the Year 2023 in the Mastercard Crescent Rating Global Muslim Travel Index (GMTI) 2023 in Singapore. Indonesia's halal tourism rose to number one from the previous number two. This increase is an extraordinary achievement. In 2021, Indonesia is ranked fourth and in 2022 second. As one of the regencies in Central Java located south of Mount Slamet, Banyumas has many natural tourist destinations. Diversity of tourism such as nature tourism, religious tourism, to educational tourism is available in Banyumas. The beauty of this tourism can be seen from the number of tourists both from within and outside the region who visit. The increase in Muslim tourists is an opportunity and challenge to improve the tourism sector in Banyumas. This research uses qualitative research methods. This qualitative research method is used as a research procedure that produces descriptive data. This research concludes that Banyumas Regency as one of the regencies in Central Java Province is known to have tourism potential that is very potential to be developed. The development of halal tourism in Banyumas still has many challenges, namely air transportation access is not yet available. Tourism destinations are not yet evenly distributed, many are concentrated in the Baturraden area. Facilities and infrastructure supporting tourism activities still need to be improved in quality and quantity. Tourism attractions are less varied. There have not been many promotional events carried out related to halal tourism. In addition to the challenges, there are certainly many opportunities for halal tourism in Banyumas, namely the strength of the natural and geographical conditions of Banyumas Regency, which is dominated by a fairly large mountainous area. There are many waterfalls and other water tourism attractions. Location on the South Java crossing route. There are several destinations with religious nuances.

Land-derived litter load to the Indian Ocean: a case study in the Cimandiri River, southern West Java, Indonesia.

The first study related to the characteristics of the riverine litter was carried out at the mouth of the Cimandiri River in the southern West Java to provide a national database, as mandated in the Indonesian Presidential Regulation 83/2018 concerning the handling of marine debris. We examined floating riverine litter entering the South Java Sea at Cimandiri River outlets four times between December 2020 and October 2021 using a Thomsea 1T trawl-net. The amount of litter collected tended to rise throughout the sampling period. Daily floating riverine litter released into the South Java Sea was estimated to be 285,931 ± 133.70 items or 307 ± 192.69kg. Our monitoring data revealed no sampling period differences in litter release into the South Java Sea with no correlation with rainfall. Our data indicate that plastics are the most single abundant type of floating riverine litter entering the South Java Sea from the Cimandiri River, accounting for 99.92% of abundance (285,701 ± 133,464.75 items per day) or 97.78% in terms of weight (300 ± 181.99kg per day) of the total litter collected. As the Cimandiri River is one of the major rivers with an outlet in the south of Java, this land-derived litter information could be an archetype for riverine ecosystems in the nation and region.

Seasonal Migration Zone of Skipjack Tuna (Katsuwonus pelamis) in the South Java Sea Using Multisensor Satellite Remote Sensing

Skipjack tuna (Katsuwonus pelamis) is the most dominating tuna species caught in the Indian Ocean. However, tuna fishermen in the Indian Ocean still face difficulties determining potential skipjack tuna fishing grounds due to limited geographic information. An attempt to improve information regarding potential skipjack tuna fishing grounds is through modeling the SST, SSC, SSH, and SSS oceanographic parameters with skipjack tuna distribution using GIS. The characteristics of the skipjack tuna habitat can be found through the generalized additive model (GAM) statistical analysis using data of skipjack tuna catch and oceanographic parameters from satellite imagery. The integrated GIS and GAM methods can improve the study of the habitat of skipjack tuna species. Therefore, this research is aimed at analyzing the condition and SST, SSC, SSH, and SSS variations in 2016-2021 in the South Java Sea; at predicting the correlation of SST, SSC, SSH, and SSS towards skipjack tuna catch in 2016-2021 in the South Java Sea using GAM; and at creating a map of skipjack tuna seasonal migration zones. The data included skipjack tuna catches, number of trips, and skipjack tuna fishing coordinates in 2016-2021 from PPS Cilacap and PPP Pondokdadap. The oceanographic parameter data in 2016-2021 was derived from Aqua MODIS level 3 (SST and SSC) and CMEMS (SSH and SSS) satellite imagery. The results showed that the average values of oceanographic parameters at skipjack tuna fishing ground coordinates in the South Java Sea (2016-2021) were SST (26.050-30.816°C), SSC (0.094-0.564 mg/m3), SSH (0.268-0.639 m), and SSS (33.075-34.514 psu). The best GAM modeling was the combination of four oceanographic parameter variables with an AIC value of 45357.92. Skipjack tuna in the South Java Sea migrates southeast during the west monsoon season to the first transitional season and tends to migrate northwest during the east monsoon season to the second transitional season.

Discerning geomorphological aspects of tsunami risk in Pangandaran, West Java, Indonesia

The geomorphological understanding of earth dynamics, including the relationship between landforms and their processes, was one of the earliest and most specific contributions to disaster prevention. Disaster geomorphology is one of the approaches in disaster studies, which includes aspects of landforms, processes, and results of physical processes that have the potential and can cause disasters. The landform is of risk factors that can turn natural hazards into natural disasters and determines the damage that disasters can cause to human activities. Following the 2006 South Java Tsunami, infrastructural development occurred massively in the 2006 South Java Tsunami inundation areas. Several tsunami risk mitigation efforts were conducted but solely based on the 2006 tsunami scenario and ignored the existence of more considerable tsunami hazards from the Sunda Megathrust. This consideration may lead to an increasing risk of future tsunamis. We evaluate and appraise favorable and unfavorable geomorphological features to reduce the risk of future tsunamis. Pangandaran has a unique landform compared to other areas on the south coast of Java, and this landform has the potential to reduce future tsunami risk. Typical landforms studied include coastal plains, alluvial plains, Tombolo, tied islands, and structural hills. The results show that the morphological features of the Tombolo and the coastal plain area are categorized as high risk when a tsunami occurs. The tied island is categorized as a favorable morphology where these morphological units have the advantage of elevation and efficient distance to the tsunami risk zone. Evacuation facilities are also needed, especially in the coastal plain and Tombolo areas (with a height of >20 meters), to reduce disaster risk, particularly mortality caused by tsunami events.

Determination of Paleotsunami Inundation Zone Using Finite Difference Method in Southern Coastal Lebak, Banten

Paleotsunami deposits have been found in Indonesia, including in Pacitan, Kulon Progo, Cilacap, Pangandaran, and Sukabumi. This research aims to obtain an ideal model for determining the paleotsunami inundation zone along the southern coastal Lebak, Banten using finite difference numerical modeling through the MOST (Method of Splitting Tsunamis)-based ComMIT software. Field observations were made to identify the presence of paleotsunami deposits in the swale area on the southern coastal Lebak, Banten. Several tsunami scenarios such as Pangandaran in 2006, Indian Ocean Tsunami (IOT) in 2004, Tohoku in 2011, Sunda Strait megathrust segment, and megathrust along the south of Java were used in the modeling process to identify the characteristics of paleotsunami that were produced the tsunami deposits in the study area. Modeling is carried out using two schemes, such as using the ComMIT database unit source (subduction zone segments) and using the earthquake source parameters that are entered manually. The results show the best tsunami scenario that may have ever occurred in research area is the tsunami event with magnitude of 9.1 Mw, with maximum inundation range of 5.2 km, and run-off of up to 32 m, which is estimated as a tsunami event that precipates paleotsunami deposits in study area.