SISTEM PERINGATAN DINI UNTUK MARAK ALGA MENGGUNAKAN CITRA SATELIT DI TELUK JAKARTA

Jakarta Bay is experiencing eutrophication, primarily due to nutrient inflows from agriculture, industry, and urban sources. This abundance of nutrients has led to significant algae blooms. A study using Terra and Aqua MODIS satellite data from 2004 to 2007 monitored these blooms by measuring chlorophyll-a levels. During this period, large-scale fish kills were observed directly related to the algal blooms, as evidenced by high chlorophyll-a concentrations and blooms covering more than a quarter of the bay. Interestingly, not all intense blooms resulted in massive fish kills. The study suggests that this mortality is primarily due to oxygen depletion after peak bloom periods, compounded by poor water circulation in the bay. Using satellite imagery to monitor algal blooms is a practical tool for implementing an early warning system (EWS) in Jakarta Bay. Satellite imagery has proven effective in monitoring these blooms and could help develop an early warning system in Jakarta Bay despite limitations such as cloud cover.Teluk Jakarta telah mengalami eutrofikasi, terutama disebabkan oleh masuknya nutrien dari sumber pertanian, industri, dan perkotaan. Kelimpahan nutrien ini telah menyebabkan terjadinya marak alga yang signifikan. Studi dengan menggunakan data satelit Terra dan Aqua MODIS dari tahun 2004 hingga 2007 telah memantau marak alga ini dengan mengukur tingkat klorofil-a. Selama periode ini, terjadi kematian massal ikan yang secara langsung terkait dengan peristiwa marak alga, seperti yang dibuktikan dengan tingginya konsentrasi klorofil-a dan marak alge yang menutupi lebih dari seperempat teluk. Menariknya, tidak semua marak alge yang intens mengakibatkan kematian ikan massal. Studi tersebut menunjukkan bahwa kematian ini terutama disebabkan oleh kekurangan oksigen setelah periode marak alge mencapai puncak, yang diperburuk oleh sirkulasi air yang lemah di teluk ini. Penggunaan citra satelit untuk memantau marak alga adalah alat yang praktis untuk menerapkan sistem peringatan dini (EWS) di Teluk Jakarta. Citra satelit telah terbukti efektif dalam memantau marak alga ini dan dapat membantu mengembangkan sistem peringatan dini di Teluk Jakarta meskipun terdapat keterbatasan seperti adanya penutupan awan

Ocean color as a proxy to predict sea surface salinity in the Banda Sea

Salinity is an important ocean parameter that greatly influences physical, chemical, and biological ocean properties and processes. Salinity combines with sea temperature and chlorophyll-a (Chl-a) that mostly sourced from remote sensing-based measurements can reveal ocean quality and supports fisheries. However, the satellite-derived Sea Surface Salinity (SSS) dataset (∼ 9 years) is not as temporally adequate as SST and Chl-a datasets (∼3 decades) and thus, preventing a comprehensively spatio-temporal analysis of this water quality aspect. Since (SSS) can be approximated using satellite-derived ocean color products having the similar temporal length of datasets to the available SST and Chl-a datasets, predicted SSS can be produced from these ocean color products to fill the gap of the existing SSS dataset. This study aims to estimate the SSS from ocean color products of Aqua-MODIS satellite with a spatial and temporal resolution of 4 km and 8-daily by developing an empirical model. The ocean color data used were remote sensing reflectance (Rrs) of blue, green and red wavelengths (412, 433, 469, 488, 531, 547, 555, 645, 667 and 678 nm). The absorption coefficients due to detritus material non-algae, Gelbstof and CDOM (ADG) at 443 nm and the absorption coefficient due to phytoplankton (APH) at 443 nm data were also used. The Banda Sea was chosen due to its large-scale upwelling system (∼300 km × 300 km) that providing an important ocean process related to fishery and the availability of in-situ salinity measurements (i.e. CTD casts from series of Research Vessel (R/V) Baruna Jaya III, VII and VIII cruises and Argo floats), which a part of these datasets will be used to validate predicted SSS. Results showed that of all ocean color parameters tested, ADG at 443 nm was strongly correlated with in-situ SSS through the polynomial order 5 regression equation with a high R2 of 0.94 and a low RMES value of 0.101 PSU. Although this empirical model has high accuracy, but based on RMSE analysis results from various locations within and outside the Banda Sea that influenced by the Pacific and the Indian ocean water masses indicates that this model actually good to predict in-situ SSS only for a narrow range SSS of 33.4-34.5 PSU. Nevertheless, this model has a limitation, it is still can be used for predicting and mapping the SSS for Banda Sea as well as for most of the Indonesian waters. The long-term meteorological SSS map (2003-2017) derived by this model together with the SST and Chl-a maps can show clearly the upwelling phenomena of the Banda Sea, which occurred during the southeast monsoon (June-July-August, JJA). This study proves that ocean color data from Aqua-MODIS satellite can be applied to estimate and to map the SSS for most of the Indonesian waters, but validations for this model is still neede

EFEKTIFKAH DAERAH PERLINDUNGAN LAUT (DPL)MENGKONSERVASI IKAN KARANG?STUDI KASUS DI KABUPATEN BIAK-NUMFOR DAN SUPIORI, PAPUA

 Sumber daya ikan karang (SDIK) dari salah satu ekosistem tropika wilayah pesisir yang sangat produktif, namun hingga kini belum diketahui stoknya, sehingga menyebabkan pengelolaan berkelanjutan sulit dilakukan,meskipun kawasan konservasi perikanan (Daerah Perlindungan Laut, DPL)sudah banyak didirikan. Tujuan kajian ini adalah mengetahui keefektifan DPL dalam konservasi SDIK di Kabupaten Biak-Numfor, dan Supiori melalui pembandingan stok SDIK dalam bentuk densitas ikan (ekor/m2) di DPL dan di luar DPL. Hasil kajian menunjukkan bahwa SDIK (ikan Target, Indikator dan Mayor) menurun drastis hampir di semua lokasi kajian, akibat pemanfaatan yang tidak ramah lingkungan pada 1995, 2001 dan 2010-2012.Perbandingan densitas SDIK di luar DPL pada 2010-2012 dan di 20 lokasi DPL tradisonal yang didirikan masyarakat di wilayah kerja Coremap LIPI pada 2008 menunjukkan bahwa densitas SDIK ikan Target, Indikator dan Mayor di DPL masing-masing lebih tinggi 3-4 kali, 3-5 kali dan 2-3 kali. DPL tradisional terbukti efektif mengkonservasi SDIK, oleh karenanya pendirian DPL perlu terus dilanjutkan di banyak lokasi, seperti target pemerintah yang akan mendirikan 20 juta ha DPL hingg 2020. DPL yang telah ada juga perlu dipantau dan dirawat secara periodik agar efektif mengkonservasi SDIK. The reef fishes resources produced from one of productive tropical ecosystem in the coastal zones have not well known yet. Thus, it is difficult to conduct sustainable management on reef fishes, desipite there are many sanctuaries (DPL) have been established in Indonesia waters. This paper aims to assess the effectiveness of DPL in the Biak-Numfor and Supiori Districts by comparing the reef fish stocks expressed as fish density (individuals/m2) between areas inside and outside DPL. Results show that the reef fish stocks (Target, Indicator and Major group) were drastically decreased in almost of study sites due to over exploitation and environmentally unfriendly fishing practises during 1995, 2001 to 2010-2012. Comparison of reef fishes density between outside DPL in 2010-2012 and inside of the 20 locations of traditional DPL established by local communities in 2008 within the Coremap LIPI working areas indicated that the density of reef fishes are 3-4, 3-5 and 2-3 times higher for Target, Indicator, and Major fish groups, respectively. Traditional DPL proves its role and its effectiveness as one of conservation tool to increase the reef fish stocks abundance Threfore, it is needed to estabish more DPL which have been targeted by government to reach 20 million ha of DPL by 2020. The exsisting DPL should be always be maintained in order they are effective in protecting the reef fish resources.

Comprehensive analysis of harmful algal blooms in indonesia: from occurrence to impact

The occurrence and frequency of harmful algal blooms have become a significant problem in Indonesia's coastal waters since 1991. This article aims to thoroughly analyze the diversity of algal species involved in these harmful algal blooms (HABs). It highlights that some algae, such as toxic species, can produce dangerous toxins, while others, such as non-toxic algae, remain harmless. This article reviews research studies that describe the occurrence, frequency, and causative types of bloom events in several contaminated coastal regions of Indonesia. The blooms had many consequences for fisheries, the aquatic environment, the economy, and public health. Among the identified species, Pyrodinium bahamense var. compressum is known for its high toxicity. The most common taxa contributing to bloom tragedy are Chaetoceros, Noctiluca, and Skeletonema. The study recognizes that human-induced nutrient enrichment is a major and significant factor in triggering the bloom phenomena. The paper recommends various management strategies and further research initiatives to prevent and reduce the impacts of HABs in Indonesia

ESTIMASI KEPADATAN DAN KEBERADAAN IKAN DI PERAIRAN KARANG TELUK SLAWI, PULAU KOMODO SUATU PENDEKATAN MELALUI METODE AKUSTIK

Penelitian tentang keberadaan stok ikan di perairan karang perairan pulau pada periode musim tenggara (Juni-Juli 2001). Daerah penelitian dibagi menjadi beberapa sub area yang mewakili perairan pantai utara dan timur. Tujuan penelitian diarahkan untuk mendapatkan keberadaan dan perkiraan kelimpahan sumber daya ikan dikawasan ini. Metode akustik sebagai salah satu perangkat pendugaan stok ikan digunakan sebagai pendukung metode sensus melalui teknik penyelaman dan pengamatan secara visual pada lintasan tansek di daerah terpilih pada masing-masing sub are

Shallow Water Habitat Mapping and Reef Fish Stock Estimation Using High Resolution Satellite Data

Shallow marine waters comprise diverse benthic types forming habitats for reef fish community, which important for the livelihood of coastal and small island inhabitants. Satellite imagery provide synoptic map of benthic habitat and further utilized to estimate reef fish stock. The objective of this research was to estimate reef fish stock in complex coral reef of Pulau Pari, by utilizing high resolution satellite imagery of the WorldView-2 in combination with field data such as visual census of reef fish. Field survey was conducted between May-August 2013 with 160 sampling points representing four sites (north, south, west, and east). The image was analy-zed and grouped into five classes of benthic habitats i.e., live coral (LC), dead coral (DC), sand (Sa), seagrass (Sg), and mix (Mx) (combination seagrass+coral and seagrass+sand). The overall accuracy of benthic habitat map was 78%. Field survey revealed that the highest live coral cover (58%) was found at the north site with fish density 3.69 and 1.50 ind/m2at 3 and 10 m depth, respectively. Meanwhile, the lowest live coral cover (18%) was found at the south site with fish density 2.79 and 2.18 ind/m2 at 3 and 10 m depth, respectively. Interpolation on fish density data in each habitat class resulted in standing stock reef fish estimation: LC (5,340,698 ind), DC (56,254,356 ind), Sa (13,370,154 ind), Sg (1,776,195 ind) and Mx (14,557,680 ind)

CHANGE DETECTION OF CORAL REEF HABITAT USING LANDSAT IMAGERY IN MOROTAI ISLAND NORTH MALUKU PROVINCE

ABSTRACT Scientific information on coral reef habitat changes of Morotai island is very limited to none. This study aimed to detect the change of coral reef habitats between 1996 and 2013, using Landsat imagery integrated with field data in 2012. The research was conducted in the coral reef ecosystem of Morotai Island in North Maluku province. Change detection analyses were conducted using supervised classifications and transformation depth invariant index (DII), with five habitat classes i.e., mixed-habitat, coral, seagrass, sand, and rubble. The result showed that in 1996-2002 there was a significant increase in the mix-habitat and rubble classes (11.3% and 32.5%), however,  there  was  a siginifcant decrease in the sand, seagrass, and coral classes of -14.1%, -14.9%, and -16.6%, respectively. In 2002-2013, mixed-habitat, sand, and seagrass classes were increase by 1.1%, 13.3%, and 24.78%, respectively.  Meanwhile, coral and rubble classes were decrease by -22.7% and -27.0%, respectively. Within the period of 1996-2013, there was about 43.6% loss of coral reef of Morotai island.  This was probably caused by the increase of seas surface temperature nad and the increase of human activities in the region. Keywords: coral reef habitats, Landsat, change detection, Morotai Islan

SHALLOW WATER HABITAT MAPPING AND REEF FISH STOCK ESTIMATION USING HIGH RESOLUTION SATELLITE DATA

Shallow marine waters comprise diverse benthic types forming habitats for reef fish community, which important for the livelihood of coastal and small island inhabitants. Satellite imagery provide synoptic map of benthic habitat and further utilized to estimate reef fish stock. The objective of this research was to estimate reef fish stock in complex coral reef of Pulau Pari, by utilizing high resolution satellite imagery of the WorldView-2 in combination with field data such as visual census of reef fish. Field survey was conducted between May-August 2013 with 160 sampling points representing four sites (north, south, west, and east). The image was analy-zed and grouped into five classes of benthic habitats i.e., live coral (LC), dead coral (DC), sand (Sa), seagrass (Sg), and mix (Mx) (combination seagrass+coral and seagrass+sand). The overall accuracy of benthic habitat map was 78%. Field survey revealed that the highest live coral cover (58%) was found at the north site with fish density 3.69 and 1.50 ind/m2at 3 and 10 m depth, respectively. Meanwhile, the lowest live coral cover (18%) was found at the south site with fish density 2.79 and 2.18  ind/m2 at 3 and 10 m depth, respectively. Interpolation on fish density data in each habitat class resulted in standing stock reef fish estimation:  LC (5,340,698 ind), DC (56,254,356 ind), Sa (13,370,154 ind), Sg (1,776,195 ind) and Mx (14,557,680 ind). Keywords: mapping, satellite imagery, benthic habitat, reef fish, stock estimatio