Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia

Reef Manta rays (Mobula alfredi) is an iconic species and under the IUCN Red List of Threatened Species it is classified as vulnerable. Although the decline of population has been reported due to their very high demand and economic value especially for their dried gill plates, they are present all y...

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Main Authors: Awaludin Ahsin, Retno Hartati, Widianingsih Widianingsih, Erlangga D. Sitorus, Hidayati Azizah, Hadi Endrawati
Format: Article
Language:English
Published: Diponegoro University; Association of Indonesian Coastal Management Experts 2022-12-01
Series:Ilmu Kelautan
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Online Access:https://ejournal.undip.ac.id/index.php/ijms/article/view/46537
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author Awaludin Ahsin
Retno Hartati
Widianingsih Widianingsih
Erlangga D. Sitorus
Hidayati Azizah
Hadi Endrawati
author_facet Awaludin Ahsin
Retno Hartati
Widianingsih Widianingsih
Erlangga D. Sitorus
Hidayati Azizah
Hadi Endrawati
author_sort Awaludin Ahsin
collection DOAJ
description Reef Manta rays (Mobula alfredi) is an iconic species and under the IUCN Red List of Threatened Species it is classified as vulnerable. Although the decline of population has been reported due to their very high demand and economic value especially for their dried gill plates, they are present all year round at Manta Sandy, Dampier Strait, Raja Ampat, Indonesia. The appearance of M. alfredi may affected by environmental factors. Therefore, this study was aimed to determine the sighted frequency of M. alfredi and their related environmental factors during east and west monsoon. Underwater Visual Census (UVC) and camera trap (PhotoID) method were used to observe the appearance of M. alfredi. The remotely oceanographic data, such as sea surface temperature, chlorophyll-a, sea surface current and tidal data, in the same M. alfredi observation time were obtained from the web of www.oceancolor.gsfc.nasa.gov, www.Hycom.org, Geospatial Information Agency (GIA) and then analyzed using Seadas, Excel, and ArcMap (Geographic Information System). The results showed that during the west monsoon M. alfredi appeared more often (174 sighting) than in the east monsoon (5 sighting). Those appearances were connected with slightly warmer sea surface temperature and high value phytoplankton which is related to zooplankton. For planktivorous elasmobranch, lower sea surface current and high tidal value affect the distribution of zooplankton in those area, so give high feeding opportunity for M. alfredi. High sighted M. alfredi during west monsoon in Manta Sandy attract tourists, therefore regulation for their conservation need to be implemented.
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language English
publishDate 2022-12-01
publisher Diponegoro University; Association of Indonesian Coastal Management Experts
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spelling doaj-art-c2a6cb8aafe94df08cf221f97b6b0afd2025-08-20T03:29:02ZengDiponegoro University; Association of Indonesian Coastal Management ExpertsIlmu Kelautan0853-72912406-75982022-12-0127433034010.14710/ik.ijms.27.4.330-34021284Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, IndonesiaAwaludin Ahsin0Retno Hartati1https://orcid.org/0000-0002-3131-5166Widianingsih Widianingsih2https://orcid.org/0000-0002-3689-3774Erlangga D. Sitorus3Hidayati Azizah4Hadi Endrawati5Department of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Diponegoro, IndonesiaDepartment of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Diponegoro, IndonesiaDepartment of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Diponegoro, IndonesiaFaculty of Science, University of the Ryukyus, JapanFaculty of Biology, National University, IndonesiaDepartment of Marine Sciences, Faculty of Fisheries and Marine Sciences, Universitas Diponegoro, IndonesiaReef Manta rays (Mobula alfredi) is an iconic species and under the IUCN Red List of Threatened Species it is classified as vulnerable. Although the decline of population has been reported due to their very high demand and economic value especially for their dried gill plates, they are present all year round at Manta Sandy, Dampier Strait, Raja Ampat, Indonesia. The appearance of M. alfredi may affected by environmental factors. Therefore, this study was aimed to determine the sighted frequency of M. alfredi and their related environmental factors during east and west monsoon. Underwater Visual Census (UVC) and camera trap (PhotoID) method were used to observe the appearance of M. alfredi. The remotely oceanographic data, such as sea surface temperature, chlorophyll-a, sea surface current and tidal data, in the same M. alfredi observation time were obtained from the web of www.oceancolor.gsfc.nasa.gov, www.Hycom.org, Geospatial Information Agency (GIA) and then analyzed using Seadas, Excel, and ArcMap (Geographic Information System). The results showed that during the west monsoon M. alfredi appeared more often (174 sighting) than in the east monsoon (5 sighting). Those appearances were connected with slightly warmer sea surface temperature and high value phytoplankton which is related to zooplankton. For planktivorous elasmobranch, lower sea surface current and high tidal value affect the distribution of zooplankton in those area, so give high feeding opportunity for M. alfredi. High sighted M. alfredi during west monsoon in Manta Sandy attract tourists, therefore regulation for their conservation need to be implemented.https://ejournal.undip.ac.id/index.php/ijms/article/view/46537m. alfrediphoto identificationsstchlorophyll-amanta sandy
spellingShingle Awaludin Ahsin
Retno Hartati
Widianingsih Widianingsih
Erlangga D. Sitorus
Hidayati Azizah
Hadi Endrawati
Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
Ilmu Kelautan
m. alfredi
photo identification
sst
chlorophyll-a
manta sandy
title Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
title_full Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
title_fullStr Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
title_full_unstemmed Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
title_short Oceanographic Factors on Coastal Aggregation of Reef Manta (Mobula alfredi) in The Manta Sandy, Raja Ampat, Indonesia
title_sort oceanographic factors on coastal aggregation of reef manta mobula alfredi in the manta sandy raja ampat indonesia
topic m. alfredi
photo identification
sst
chlorophyll-a
manta sandy
url https://ejournal.undip.ac.id/index.php/ijms/article/view/46537
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