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  1. Article ; Online: Residency, movement patterns, behavior and demographics of reef manta rays in Komodo National Park

    Elitza S. Germanov / Simon J. Pierce / Andrea D. Marshall / I. Gede Hendrawan / Ande Kefi / Lars Bejder / Neil Loneragan

    PeerJ, Vol 10, p e

    2022  Volume 13302

    Abstract: Background The reef manta ray (Mobula alfredi) is a globally threatened species and an iconic tourist attraction for visitors to Indonesia’s Komodo National Park (NP). In 2013, manta ray fishing was banned in Komodo NP and its surroundings, preceding the ...

    Abstract Background The reef manta ray (Mobula alfredi) is a globally threatened species and an iconic tourist attraction for visitors to Indonesia’s Komodo National Park (NP). In 2013, manta ray fishing was banned in Komodo NP and its surroundings, preceding the nationwide manta ray protection in 2014. Over a decade ago, a previous acoustic telemetry study demonstrated that reef manta rays had high fidelity to sites within the park, while more recent photo-identification data indicated that some individuals move up to 450 km elsewhere. Characterization of manta ray demographics, behavior, and a focused assessment on site use of popular tourism locations within the park is vital to assist the Komodo NP Management Authority formulate appropriate manta ray conservation and management policies. Methods This study uses a long-term library (MantaMatcher.org) of photo-identification data collected by researchers and citizen scientists to investigate manta ray demographics and habitat use within the park at four sites frequented by tour operators: Cauldron, Karang Makassar, Mawan, and Manta Alley. Residency and movements of manta rays were investigated with maximum likelihood analyses and Markov movement models. Results A total of 1,085 individual manta rays were identified from photographs dating from 2013 to 2018. In general, individual manta rays displayed a higher affinity to specific sites than others. The highest re-sighting probabilities came from the remote southern site, Manta Alley. Karang Makassar and Mawan are only ~5 km apart; however, manta rays displayed distinct site affinities. Exchange of individuals between Manta Alley and the two central sites (~35.5 km apart) occurred, particularly seasonally. More manta rays were recorded traveling from the south to the central area than vice versa. Female manta rays were more mobile than males. Similar demographic groups used Karang Makassar, Mawan, and Manta Alley for foraging, cleaning, cruising, or courtship activities. Conversely, a higher proportion of immature manta ...
    Keywords Elasmobranch ; Photo-ID ; Population structure ; Movement ; Site use ; Tourism ; Medicine ; R
    Subject code 910 ; 333
    Language English
    Publishing date 2022-05-01T00:00:00Z
    Publisher PeerJ Inc.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: THE VULNERABILITY STUDY OF LEMURU (SARDINELLA LEMURU) FISH RESOURCES SUSTAINABILITY IN BALI STRAIT IN CORELLATION WITH ENSO AND IOD

    Candra Saputra / I Wayan Arthana / I Gede Hendrawan

    Ecotrophic: Journal of Environmental Science, Vol 11, Iss 2, Pp 140-

    2017  Volume 147

    Abstract: The aim of this research is to know the relationship between lemuru fish catch to Sea Surface Temperature (SST), El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) phenomenon in Bali Strait. The results showed, that in the period 2007 – ... ...

    Abstract The aim of this research is to know the relationship between lemuru fish catch to Sea Surface Temperature (SST), El-Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) phenomenon in Bali Strait. The results showed, that in the period 2007 – 2016. fluctuations of catches lemuru tends to decline. Sea Surface Temperature (SST) distribution with the lowest temperature 25,28oC at 24,53oC - 27,16oC and the highest temperature is 29,31oC in the range of 28,730C – 30,490C. The lowest temperature occurred in July - September while the highest temperature occurred in January - April. Based on the calculation there is a linkage and relationship between catch and SST as shown on the value of determination and correlation reached 50,0% and 70,73%. Most of the catches occurred in the west season and then the transition II, transition I and East Season. The relationship of ENSO phenomenon to the catch during the El-Nino phase of lemuru catch will increase while in the phase of La-Nina the catch of lemuru will decrease, because time of El-Nino phase of the sea surface temperature (SST) relative low which results in the chlorophyll-a mean case which is a food sources of lemuru fish. Based on Trenberth's theory, (1997), the rise and fall of the ENSO Index of less than six months is not stated in ENSO. From the calculation results during the research of 2007 - 2016 happened three times ENSO phenomenon that is in 2009, 2010 and 2015. At the time of the IOD phenomenon, the IOD (+) phase will result in a decrease in catch while the normal IOD phase and (-) will increase the catch. From the results of this study can also be observed, in the year 2007 - 2011 phenomenon ENSO and IOD have a strong influence on the catch while in the year 2012 - 2016 the influence of the phenomenon of ENSO and IOD has no strong influence caused by the quantity of lemuru fish that have been over exploitation that resulted in the current Bali Strait on Over Fishing status. Keywords : Fish Catch; El-Nino Southern Oscillation (ENSO); Indian Ocean Dipole (IOD)
    Keywords Environmental sciences ; GE1-350
    Subject code 551
    Language English
    Publishing date 2017-11-01T00:00:00Z
    Publisher Universitas Udayana
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: PEMETAAN HABITAT PERAIRAN DANGKAL DI KAWASAN PADAT WISATA TANJUNG BENOA BALI MENGGUNAKAN DATA REMOTE SENSING

    I Wayan Gede Astawa Karang / I Wayan Matsya Deva Nagendra / I Dewa Made Khrisna Putra Astaman / I Gede Hendrawan

    Ecotrophic: Journal of Environmental Science, Vol 13, Iss 2, Pp 227-

    2019  Volume 237

    Abstract: Tourism is a sector that is prioritized in various countries. Most of the tourist objects are distributed along the coast that intersects directly with those that result in the degradation of the ecosystem inside. The southern region of Bali is one of ... ...

    Abstract Tourism is a sector that is prioritized in various countries. Most of the tourist objects are distributed along the coast that intersects directly with those that result in the degradation of the ecosystem inside. The southern region of Bali is one of the regions that has experienced rapid development of tourism activities. The expansion of the tourism area in Tanjung Benoa occurs in coastal areas and directly contacts underwater ecosystems such as seagrass beds and coral reefs, which it have an impact on changes in the area of the ecosystem. Information about the form of distribution of underwater objects can be the first step in making ecological-based tourism policy. Satellite imagery can be used to detect shallow-water habitats. The purpose of this study was to determine the effectiveness of sentinel-2 A images to map shallow water habitat in densely packed tourist areas Tanjung Benoa. The results showed that there were three types of land cover in Tanjung Benoa area, such as seagrass, coral and sand, the accuracy results showed landsat 8 images had higher accuracy than Sentinel-2 A images with total accuracy of 74.83% and kappa accuracy of 46.59%. There are 8 types of seagrasses species in the coastal area of Tanjung Benoa, namely Cymodocea rotundata, Enhalus acoroides, Halodule pinifolia, Halodule uninervis, Halophila ovalis, Thalassia hemprichi Syringodium isoetifolium dan Thalassodendron Ciliatum. Keywords: Remote Sensing; Shallow Water Habitat; Tanjung Benoa; Sentinel-2 A; Landsat 8
    Keywords Environmental sciences ; GE1-350
    Subject code 910
    Language English
    Publishing date 2019-11-01T00:00:00Z
    Publisher Universitas Udayana
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: WATER POLLUTION LEVELS IN THE SUWUNG ESTUARY, BALI, BASED ON BIOLOGICAL OXYGEN DEMAND

    Ni Luh Gede Rai Ayu Saraswati / I Wayan Arthana / I Gede Surya Risuana / I Gede Hendrawan

    Biotropia: The Southeast Asian Journal of Tropical Biology, Vol 25, Iss

    2018  Volume 3

    Abstract: Biological Oxygen Demand (BOD) is generally used for determining water pollution levels in bodies of water. Estuary is a semi-enclosed body of water that can be polluted via land areas or rivers. This study was conducted to determine the spatial ... ...

    Abstract Biological Oxygen Demand (BOD) is generally used for determining water pollution levels in bodies of water. Estuary is a semi-enclosed body of water that can be polluted via land areas or rivers. This study was conducted to determine the spatial distribution of water pollution levels in the Suwung Estuary in Bali based on BOD5 analyses conducted in January and February 2016. Samples were taken in 20 points (19 points in the Suwung Estuary and 1 outside the Suwung Estuary as control). BOD5 samples were then analysed in the laboratory. Our BOD5 analyses used the amperometric method based on the National Field Manual for the Collection of Data Water-Quality, Chapter A7. BOD5 samples were taken at all tide cycles, during low to high tide and high to low tide. BOD5 values ranged from 0.84 mg/L–9.47 mg/L during lowto high tide and 0.96 mg/L–8.75 mg/L during high to low tide. Results of the BOD5 analyses showed slight contamination in the Suwung Estuary during both tidal conditions. The BOD5 values’ spatial distribution showed higher values around cage aquacultures, rivers, the Suwung Landfill, and around the Benoa Harbour.
    Keywords BOD5 ; spatial distribution ; Suwung Estuary ; water pollution level ; Biology (General) ; QH301-705.5 ; Ecology ; QH540-549.5
    Subject code 333
    Language English
    Publishing date 2018-09-01T00:00:00Z
    Publisher SEAMEO, BIOTROP
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Underwater noise from airplanes: An overlooked source of ocean noise

    Erbe, Christine / I Gede Hendrawan / I. Made Iwan Dewantama / Miles Parsons / Rob Williams / Sylvia K. Parsons

    Marine pollution bulletin. 2018 Dec., v. 137

    2018  

    Abstract: The effects of underwater noise pollution on marine life are of increasing concern. Research and management have focussed on the strongest underwater sound sources. Aerial sound sources have understandably been ignored as sound transmits poorly across ... ...

    Abstract The effects of underwater noise pollution on marine life are of increasing concern. Research and management have focussed on the strongest underwater sound sources. Aerial sound sources have understandably been ignored as sound transmits poorly across the air-water interface. However, there might be situations when air-borne noise cannot be dismissed. Commercial passenger airplanes were recorded in a coastal underwater soundscape exhibiting broadband received levels of 84–132 dB re 1 μPa rms. Power spectral density levels of airplane noise underwater exceeded ambient levels between 12 Hz and 2 or 10 kHz (depending on site) by up to 36 dB. Underwater noise from airplanes is expected to be audible to a variety of marine fauna, including seals, manatees, and dolphins. With many of the world's airports lying close to the coast, it is cautioned that airplane noise not be ignored, in particular in the case of at-risk species in small, confined habitats.
    Keywords airplanes ; airports ; coasts ; dolphins ; fauna ; habitats ; liquid-air interface ; noise pollution ; seals ; sounds ; Trichechus ; water pollution
    Language English
    Dates of publication 2018-12
    Size p. 656-661.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2001296-2
    ISSN 1879-3363 ; 0025-326X
    ISSN (online) 1879-3363
    ISSN 0025-326X
    DOI 10.1016/j.marpolbul.2018.10.064
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Contrasting Habitat Use and Population Dynamics of Reef Manta Rays Within the Nusa Penida Marine Protected Area, Indonesia

    Elitza S. Germanov / Lars Bejder / Delphine B. H. Chabanne / Dharmadi Dharmadi / I. Gede Hendrawan / Andrea D. Marshall / Simon J. Pierce / Mike van Keulen / Neil R. Loneragan

    Frontiers in Marine Science, Vol

    2019  Volume 6

    Abstract: Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics and movements. We investigate the population structure ...

    Abstract Manta rays (Mobula spp.) are highly valued in nature-based tourism globally. In Indonesia, although manta rays are protected, critical information is lacking on their habitat use, population dynamics and movements. We investigate the population structure and residency patterns of reef manta rays (Mobula alfredi) in the Nusa Penida Marine Protected Area (MPA). From photo-identification data logged by citizen scientists and trained observers (mantamatcher.org), we identified 624 reef manta rays from 5,913 sightings (January 2012–April 2018) based on their unique ventral coloration patterns. Year-round records were collected from two shallow (<20 m) reefs – Manta Bay (MB; n = 3,029 sightings) and Manta Point (MP; n = 3,058) – that are used frequently by tourism operators. Maximum likelihood techniques and a Markov movement analysis were used to model residency patterns and movement between these sites within the MPA. Manta rays at MB were predominantly male (64%, n = 261 individuals), with immature males (14%, n = 59) being sighted most frequently (39%, n = 1,170). In contrast, few immature individuals were sighted at MP (6%, n = 28), and they were sighted on few occasions (2%, n = 45), while mature female manta rays comprised 26% (n = 127) of the MP community and were the most frequently sighted (48%, n = 1,413). Lagged identification rates indicated high site fidelity at each location. However, 44% (n = 278) of individuals moved between the two sites and cumulative discovery curves showed a continued recruitment of individuals over the 6 years of the study. In addition, the behaviors displayed by the manta rays differed markedly between the two sites: MB appears to be a foraging ground, especially for juveniles, and potentially a nursery, while MP is used mainly for cleaning and courtship, indicating a social and reproductive site. Reproductive behavior coincided with the peak annual sightings in May. To prevent disturbance to this threatened species by tourism, regulations for the number of boats and interactions, especially during key reproductive times should be considered. Further, strict fishing regulation in the area is recommended as fishing gear entanglement was identified as a threat to this population.
    Keywords Mobula alfredi ; citizen science ; photo-identification ; population structure ; animal behavior ; site fidelity ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Subject code 590
    Language English
    Publishing date 2019-05-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Microplastics on the Menu

    Elitza S. Germanov / Andrea D. Marshall / I. Gede Hendrawan / Ryan Admiraal / Christoph A. Rohner / Janis Argeswara / Raka Wulandari / Mahardika R. Himawan / Neil R. Loneragan

    Frontiers in Marine Science, Vol

    Plastics Pollute Indonesian Manta Ray and Whale Shark Feeding Grounds

    2019  Volume 6

    Abstract: The implications of plastic pollution, including microplastics, on marine ecosystems and species are increasingly seen as an environmental disaster. Yet few reports focus on filter-feeding megafauna in regions heavily impacted by plastic pollution, such ... ...

    Abstract The implications of plastic pollution, including microplastics, on marine ecosystems and species are increasingly seen as an environmental disaster. Yet few reports focus on filter-feeding megafauna in regions heavily impacted by plastic pollution, such as Indonesia in the Coral Triangle, a global marine biodiversity hotspot. Here, we evaluate plastic abundance and characterize debris from feeding grounds for manta rays Mobula alfredi and whale sharks Rhincodon typus in three coastal locations in Indonesia: Nusa Penida Marine Protected Area, Komodo National Park, and Pantai Bentar, East Java. A 200 μm plankton net was used to sample the top 0.5 m of the water column (‘trawl survey’) and floating plastics were assessed along ∼440 m long transects (‘visual survey’) during the Indonesian north-west (wet) and south-east (dry) monsoon seasons during 2016–2018. Microplastics were identified visually, measured and categorized from trawl samples, and larger floating plastics were counted and categorized visually from boats. Plastic abundance ranged widely from 0.04 to 0.90 pieces m–3 (trawl survey) and 210 to 40,844 pieces km–2 (visual survey). Results from linear models showed significant seasonal and location differences in estimated plastic abundance for trawl and visual surveys in Nusa Penida and Komodo. Plastic abundance was up to ∼ 44 times higher in the wet than the dry season, with the largest seasonal effect observed in Nusa Penida. Overall, small pieces < 5 mm (≥ 78%), films and fragments (> 50% combined) were the most prevalent plastics. Theoretical plastic ingestion rates were calculated using estimated filtration volumes of manta rays and whale sharks and the mean plastic abundance in their feeding grounds. Upper plastic ingestion estimates for manta rays were ∼63 and 25 pieces h–1 for Nusa Penida and Komodo locations, respectively, and ∼137 pieces h–1 for whale sharks in Java. Analysis of manta ray egested material confirmed plastic ingestion, the consequences of which might include exposure to toxic plastic additives and adhered persistent organic pollutants. Communicating this information to communities who stand to benefit from healthy megafauna populations might help local governments as they work toward reducing plastics in the marine environment.
    Keywords Mobula alfredi ; Rhincodon typus ; marine debris ; conservation ecology ; flagship species ; base-line ; Science ; Q ; General. Including nature conservation ; geographical distribution ; QH1-199.5
    Subject code 333
    Language English
    Publishing date 2019-11-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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