Modeling potential distribution of Indo-Pacific humpback dolphins (Sousa chinensis) in the Beibu Gulf, China
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Abstract
Background. Mapping key habitats of marine mega-vertebrates with high mobility is crucial for species conservation. Due to difficulties in obtaining sound data in the field, Species Distribution Modeling (SDM) provides an effective alternative to identify habitats. As a keystone and flagship species in inshore waters in southern China, Indo-Pacific humpback dolphins (Sousa chinensis) play an important role in coastal ecosystems. However, our knowledge on their key habitats remained unclear in some waters including the Beibu Gulf of South China Sea.
Methods. We used a maximum entropy (Maxent) modeling approach to predict potential habitats for Sousa chinensis in the Beibu Gulf of China. Models were based on eight independent oceanographic variables derived from Google Earth Digital Elevation Model (DEM) and Landsat images, and presence-only sighting data from boat-based surveys and literatures during 2003-2013.
Results. Three variables, distance to major river mouths, to coast and to 10-m isobaths, were the strongest predictors, consistent with other studies on the dolphin habitat selection. Furthermore, we confirmed that influence of estuaries was the most important and irreplaceable. Besides two known distribution areas as well as data sources, a new area close to the boundary of China and Vietnam, Beilunhe Estuary (BE), was predicted as a potential habitat.
Discussion. Influence of estuaries is likely to indicate feeding preference of the humpback dolphins. The “new” habitat BE should be a key area connecting China and Vietnam dolphins, and deserved to be examined and preserved.
Cite this as
2016. Modeling potential distribution of Indo-Pacific humpback dolphins (Sousa chinensis) in the Beibu Gulf, China. PeerJ Preprints 4:e2101v2 https://doi.org/10.7287/peerj.preprints.2101v2Author comment
We adjusted format of figures, modified some grammer mistakes and improved consistency of the context in the revised version. This version has been submitted to PeerJ for review.
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Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Mei Chen conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.
Yuqin Song conceived and designed the experiments, reviewed drafts of the paper.
Dagong Qin performed the experiments, reviewed drafts of the paper.
Animal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):
Our field work was permitted and supported by the Sanniang Bay Management Committee, which is part of the local government. We conducted boat-based survey approach. When we surveying, trained observers looked for the dolphins with the naked eye. We maintained at least 50-meter distance from the animals unless they swam close to us initiatively, for both observation and following them. There is no touching, feeding, and other improper behaviors with the dolphins. Therefore, approval from animal ethics committee is not required under Chinese Law.
Data Deposition
The following information was supplied regarding data availability:
The raw data has been supplied as a supplementary file.
Funding
The authors received no funding for this work.