Echolocation Clicks of Irrawaddy Dolphins (Orcaella brevirostris) During Foraging in the Bay of Brunei, Malaysia

Muhamad, Hairul Masrini; Xu, Xiaomei; Zhang, Xuelei; Jaaman, Saifullah Arifin; Muda, Azmi Marzuki; Ismail, Farah Dayana Haji; Azizul, Nurlisa

doi:10.1007/s40857-020-00183-5

Cited by 5 publications

(3 citation statements)

References 51 publications

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“…Under the development of coastal areas and changes in coastal ecosystems, establishing baseline data on the health status and body condition of foraging green turtles is important. Since Brunei Bay remains relatively unpolluted [25,26] and biodiverse [23,24], the values of hematology parameters and Fulton's body condition index in this study will be referred to as baseline data. This study also indicated a seasonal change in size composition possibly related to reproduction.…”

Section: Discussionmentioning

confidence: 99%

“…Brunei Bay, situated in the South China Sea, is an important foraging ground for green turtles [21], accommodating a considerable population of juvenile and adult turtles that originate from Southeast Asian rookeries, particularly the Sulu Sea population [21,22]. The bay's rich marine ecosystem supports diverse wildlife, including the dugong, Dugong dugon [23] and Irrawaddy dolphins, Orcaella brevirostris [24], which forage in the region. Despite the presence of contaminants at relatively low levels [25,26], the activities of humans and industries, such as microplastics, remain a concern [27].…”

Section: Introductionmentioning

confidence: 99%

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Health status and genetic compositions of green turtles (Chelonia mydas) foraging in Brunei Bay

Joseph,

Nishizawa,

Jalimin

et al. 2023

PLoS ONE

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Long-term monitoring of sea turtle aggregations is critical for understanding the impacts of environmental changes on their population health and habitat suitability. Brunei Bay is a significant foraging ground for green turtles in the South China Sea. We analyzed the body size, hematology and body condition of green turtles for their health status in their foraging ground in Brunei Bay over a period of nine years (2011–2019). Additionally, we used mitochondrial DNA (mtDNA) to evaluate changes in the size and genetic composition of green turtle aggregations. Our findings revealed that the size composition of the green turtle population varied seasonally, but there were no significant temporal changes in genetic and size compositions. Hematology parameters and Fulton’s body condition index were consistent with those reported for apparently healthy green turtles. Furthermore, we found that blood reference intervals indicated the turtles were healthy. These results provide valuable baseline data for future comparisons with other foraging aggregations and for long-term monitoring of green turtles in Brunei Bay.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Health status and genetic compositions of green turtles (Chelonia mydas) foraging in Brunei Bay

Joseph,

Nishizawa,

Jalimin

et al. 2023

PLoS ONE

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“…In the Bay of Brunei, whilst Irrawaddy dolphins have been sighted in Brunei waters (Elkin 1992;Gibson-Hill 1950, 1949Jiang et al 2020;Stacey & Letherwood 1997;Weber 1923), much of the literature for the region focuses on the species in Malaysian waters. Past studies on Irrawaddy dolphin in Malaysia side of the bay have been mostly investigated on their distribution, population, abundance, and acoustics (Jaaman et al 2016;Jiang et al 2020Jiang et al , 2019Mahmud 2016;Mahmud et al 2018aMahmud et al , 2018bMuhamad et al 2020Muhamad et al , 2018. Species presence in the bay may be due to favorable environmental conditions.…”

Section: Introductionmentioning

confidence: 99%

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2021

JSM

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The uniqueness of the Bay of Brunei makes it an ideal place to be inhabited by Irrawaddy dolphins. However, the increasing potential impacts of anthropogenic factors and environmental changes on the dolphins are alarming. The objectives of this study were to determine the seasonal occurrence and distribution, and to estimate the group size of Irrawaddy dolphins in the Bay of Brunei. Surveys were conducted between January 2016 and April 2018. The total distance surveyed was 2,439.2 km in 189.13 h (survey effort = 13,081.93 km.h). Forty-nine groups of Irrawaddy dolphins were recorded with a sighting rate of 0.37 per 100 km.h. Thirteen of the groups were observed with calves. Overall, the group size ranged between 1 and 15 individuals with a mean of 4.5 individuals (SD = 3.3). There was no statistical significance in the number of dolphin sightings between four different monsoon seasons (Northeast, Southwest, April Inter-monsoon, and October Inter-monsoon) (χ 2 = 5.66, df = 3, p > 0.05). The number of sightings and number of individuals suggest that Irrawaddy dolphins are residents of the Bay of Brunei and are in need of a conservation management plan.

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A novel age-group classification method for Irrawaddy dolphins based on dorsal fin shape features

Sheng

Wang

et al. 2022

Ecological Informatics

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Echolocation Clicks of Irrawaddy Dolphins (Orcaella brevirostris) During Foraging in the Bay of Brunei, Malaysia

Cited by 5 publications

References 51 publications

Health status and genetic compositions of green turtles (Chelonia mydas) foraging in Brunei Bay

Health status and genetic compositions of green turtles (Chelonia mydas) foraging in Brunei Bay

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A novel age-group classification method for Irrawaddy dolphins based on dorsal fin shape features

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