CD Tesis

Analisis Vegetasi Mangrove Menggunakan Pesawat Nirawak (Drone) dan Kelimpahan Udang Galah Pada Beberapa Sungai di Pulau Bengkalis

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Mangroves on Bengkalis Island have decreased by 2,514.15 hectares between 2000 and 2019. This decline was caused by anthropogenic activities and natural factors, such as abrasion. Anthropogenic activities were carried out by residents along the Jangkang River, Liong River, and Kembung Luar River. These activities include utilizing mangroves as raw materials for charcoal, cerocok (construction poles), and firewood for household use. Additionally, the conversion of mangrove forests into shrimp ponds in several river locations on Bengkalis Island has contributed to organic pollution from feed residues, which can ultimately lead to eutrophication. The degradation of mangrove forests disrupts the life cycle and distribution of giant freshwater prawns, which rely on the waters around mangroves as their habitat. Therefore, updated information on the condition of mangrove forests and the abundance of giant freshwater prawns on Bengkalis Island is needed.
The purpose of this study was to assess the condition of mangroves in four rivers on Bengkalis Island, determine the abundance of giant freshwater prawns in each river, and analyze the relationship between the abundance of giant freshwater prawns, mangrove vegetation conditions, and other environmental parameters.
This study was conducted in March 2024 in four rivers on Bengkalis Island: Jangkang River, Liong River, Kembung Luar River, and Sebauk River. The tools used included a DJI Mavic 2 Pro Quadcopter Drone, nine bubu (shrimp traps) equipped with mounting equipment, and instruments for measuring water chemistry and physics. Cassava and pellets were used as bait.
Mangrove canopy cover was studied by taking aerial photographs using a drone at an altitude of 50 m, with a pixel resolution or ground sample distance (GSD) of 1.81 cm/pixel and 80% overlap. The surveyed area measured 100 m x 100 m. Flight paths were created using the Pix4D application. Sampling was conducted at three stations (upstream, midstream, and downstream). Prawn abundance was studied simultaneously with canopy cover assessments. Shrimp traps with bait were deployed at the three stations at 30-meter intervals and left for approximately six hours. Mangrove vegetation was analyzed by processing aerial photographs with Agisoft software through a mosaicking process. A spatial approach using high-resolution imagery was employed, focusing on canopy appearance and mangrove locations. Mangroves were identified through an on-screen digitizing process. Measurements of physical and chemical parameters were conducted on-site, while biological parameters, such as plankton abundance, were obtained from secondary data.
The results showed a total of 11 mangrove species across all rivers. A total of 29 giant freshwater prawns (Macrobrachium rosenbergii) were caught, with individuals found in all rivers except Kembung Luar River. The relative abundance of giant freshwater prawns was highest in the downstream section of Liong River (100%), followed by the midstream section (86%), upstream Sebauk River (83%), upstream Jangkang River (78%), midstream Jangkang River (43%), and upstream Liong River (14%). The most common size class of giant freshwater prawns was juveniles (3–6 cm). Water temperature ranged from 29°C to 35.4°C, current velocity from 0.04 to 0.27 m/s, and water transparency from 18.5 to 117.5 cm. Salinity ranged from 15 to 25 ppt, while the water pH was between 5.1 and 11.9. Soil pH in mangrove areas ranged from 5.2 to 6.9. Dissolved oxygen (DO) levels varied from 4.5 to 13.6 mg/L. Plankton abundance across all rivers ranged from 366 to 1,400 individuals per liter.
In conclusion, the mangroves in the study area were classified as dense, with canopy cover exceeding 70%. Giant freshwater prawn abundance was highest in Liong River, followed by Sebauk River and Jangkang River, while no prawns were found in Kembung Luar River. There was no significant relationship between mangrove condition and giant freshwater prawn abundance. The most influential factors on giant freshwater prawn abundance were water transparency and salinity.

Keywords: Anthropogenic, aerial photography, supervised image classification, land cover

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Ketersediaan

Informasi Detail

Judul Seri

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No. Panggil

2210247848

Penerbit

Pekanbaru : Universitas Riau Pascasarjana Tesis Pendidikan Biologi., 2024

Deskripsi Fisik

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Bahasa

Indonesia

ISBN/ISSN

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Klasifikasi

2210247848

Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

PENDIDIKAN BIOLOGI

Info Detail Spesifik

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Pernyataan Tanggungjawab

Jaka

Versi lain/terkait

Lampiran Berkas

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