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I Putu Yogi Darmendra
Program Studi Ilmu Kelautan, Fakultas Kelautan dan Perikanan, Universitas Udayana, Bali, Indonesia
Earth & Planetary Sciences

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Pemetaan Batimetri Perairan Dangkal Menggunakan Citra Satelit Sentinel-2a Dan Landsat 8 Perairan Pantai Matahari Terbit, Bali Ravienkha Raishasaras Budaya; I Gusti iNgurah Putra Dirgayusaa; I Putu Yogi Darmendra
Journal of Marine Research and Technology Vol 6 No 2 (2023): AGUSTUS 2023
Publisher : Department of Marine Sciences, Faculty of Marine and Fisheries, Universitas Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JMRT.2023.v06.i02.p12

Abstract

Bathymetric mapping has an important role for human activities, especially in the marine and fisheries field. However, conventional measurement of bathymetry in coastal areas is quite time consuming, high cost and difficult ship access. With the advancement of current technology, remote sensing technology using satellite imagery is believed to overcome these obstacles. In practice, there are several satellite imagery that can be used, with its own advantages and disadvantages that differ from each other. This study compared two open access satellite imagery with different resolutions Sentinel-2A and Landsat 8 by applying Lyzenga’s algorithm to estimate depth in Matahari Terbit Beach Waters, Bali. The depth data estimated from these satellites imageries then validated with in situ measurement data collected in November 2012. To obtain the absolute depth and know the relation between the relative depth of the image and the in situ depth is carried out Inverse regression analysis. The results of the analysis using Sentinel-2A obtained an estimated absolute depth of 0 – 7.1 meters with R2 = 0.705 and RMSE 6.165324. While the analysis using Landsat 8 obtained an estimated absolute depth of 0 – 5.5 meters with R2 = 0.588 and RMSE 7.086484. The results showed that the data obtained using Sentinel-2A satellite imagery was better than Landsat 8’s imagery, which could be due to differences in image spatial resolution and water conditions when the images were recorded.
Kandungan Mikroplastik Pada Gastropoda di Kawasan Tahura Ngurah Rai, Bali Gulielmus Nanda Iobel Arijuato; I Gede Hendrawan; I Putu Yogi Darmendra
Journal of Marine Research and Technology Vol 6 No 2 (2023): AGUSTUS 2023
Publisher : Department of Marine Sciences, Faculty of Marine and Fisheries, Universitas Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JMRT.2023.v06.i02.p05

Abstract

The mangrove ecosystem can be affected by the dangers of microplastics, indicated by various associated biota that lives in it, one of them being gastropods. This study aimed to determine microplastics’ content in gastropod body mangrove sediments at Tahura Ngurah Rai, Bali using gastropods as bioindicators. This research was conducted from May to June 2022, using in situ and ex situ methods. In situ, data were conducted at Tahura Ngurah Rai, Bali, as the sampling location, and ex situ data were conducted at Udayana University’s marine science laboratory by sample processing. The data taken includes the characteristics of microplastics, including the type, size, color, and abundance of microplastics in gastropods at the sampling station. Results showed that 5 families of gastropods (Ellobiidae, Littorinidae, Muricidae, Neritidae, and Potamididae) were contaminated with microplastics, with the highest abundance found in Potamididae, with the number 4,06 ± 2,19 particles/individual. The types of microplastics obtained were fragments, fibers, and films dominated by fibers collected 210 particles. The color of the microplastics varies and dominated with black colored microplastics was found 78 particles, and the size of microplastics is dominated by < 1 mm particles with several 145 particles. The highest abundance of microplastics was found on site 12 with the number 5,67 ± 4,04 particles/individual.
Analisis Isi Perut Ikan Apogonidae di Teluk Gilimanuk, Bali Ni Luh Putu Emi Trisna Dewi; I Nyoman Giri Putra; I Putu Yogi Darmendra
Journal of Marine Research and Technology Vol 7 No 1 (2024): FEBRUARI 2024
Publisher : Department of Marine Sciences, Faculty of Marine and Fisheries, Universitas Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JMRT.2024.v07.i01.p04

Abstract

The types of natural food consumed by fish can vary according to their species and its age level. The purpose of this study was to determine the types of organisms feed by Apogonidae fishes by observing their gut contents and to determine the type of feeding habits of these fishes. This research was conducted at two sampling sites within Gilimanuk Bay, Bali. Specimen collection was conducted in the morning (07.00 am) using a scoop net while scuba diving. We successfully collected 32 individual Apogonidae, which consist of eight species. Each sample was dissected and the contents of the stomach were removed from the esophagus to the intestine. The stomach contents were preserved using 4% formalin, and then the samples were observed under a binocular microscope with 40x magnification. The results showed that the highest composition of food species found as the main food was the Copepod of 59.86% which was fed by Sphaeramia nematoptera, Cheilodipterus artus, Fibramia thermalis, Pterapogon kaudernii, Zoramia leptacantha, Rhabdamia gracilis, and Ostorhichus hoevenii, Bacillariophyceae by 31.97% were feed by S. nematoptera, C. artus, O. hartzfeldii, F. thermalis, P. kauderni, Z. leptacantha, R. gracilis, and O. hoevenii. The other class of plankton only made up a small part of the food composition of the Apogonidae fishes, which is as much as 8.16%. Based on our results, we conclude that Apogonidae fishes in Gilimanuk Bay were plankton feeders where all the food found comes from phytoplankton and zooplankton organisms.
Pemetaan Terumbu Karang Berbasis Citra Unmanned Aerial Vehicle (UAV) Dan Satelit Sentinel-2A Dengan Metode Object Based Image Analysis (OBIA) Di Perairan Pulau Menjangan Bali Ramadhani Ahmad; I Dewa Nyoman Nurweda Putra; I Putu Yogi Darmendra
Journal of Marine Research and Technology Vol 7 No 1 (2024): FEBRUARI 2024
Publisher : Department of Marine Sciences, Faculty of Marine and Fisheries, Universitas Udayana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/JMRT.2024.v07.i01.p05

Abstract

There is still little research on mapping benthic habitats on Menjangan Island, so the availability of spatial data in this area is still limited. This research aimed to map coral reefs using UAV imagery and Sentinel-2A imagery with the object-based/OBIA classification method and calculate the level of accuracy of classification results in the waters of Menjangan Island. This research was conducted in 4 water areas, especially waters where diving and snorkeling activities often occur. This research used Sentinel-2A satellite data acquired on March 17, 2022, and UAV data acquired on March 30, 2022. Area 1 live coral (KH) with an area of 0.76 Ha for UAV imagery, live coral (KH) on Sentinel imagery -2A, namely 0.64 Ha. Region 2, the area of live coral (KH) in the UAV image is 0.67 Ha, and live coral (KH) in the Sentinel-2A image is 0.49 Ha. Region 3, the area of live coral (KH) in the UAV image is 0.77 Ha; in the Sentinel-2A image, it is 0.60 Ha. The 4 live coral (KH) areas in the UAV image have an area of 0.83 Ha, and the live coral (KH) in the Sentinel-2A image covers an area of 0.62091 Ha. UAV imagery can produce an overall accuracy in each region of 97.96% in Region 1. 98.21% in Region 2, 98.84% in Region 3, and 96.77% in Region 4. The overall accuracy level of Sentinel-2A imagery is 85.71% in Region 1, 83.93% in Region 2, 86.05% in Region 3, and 83.87% in Region 4.
Co-Authors Gulielmus Nanda Iobel Arijuato I Dewa Nym. Nurweda P., I Gede Hendrawan I Gusti iNgurah Putra Dirgayusaa Ni Luh Putu Emi Trisna Dewi Putra, I Nyoman Giri Ramadhani Ahmad Ravienkha Raishasaras Budaya