Environmental models for predicting habitat of the Indo‐Pacific humpback dolphins in Fujian, China

Abstract

1. The coast of Fujian Province is a key area for the Indo-Pacific humpback dolphin (Sousa chinensis), but the characteristics of their preferred habitats are poorly defined. 2. The species distribution model, MaxEnt, was used to predict suitable habitat distributions of humpback dolphins in Fujian, China. The model indicated that the distance to the coastline (63.5% contribution), chlorophyll-a levels (20.2%) and the bathymetry (15.6%) were important predictors of humpback dolphin habitats. 3. The model predicted 2,043.96 km 2 of highly suitable habitat that was concentrated in five areas. Four are known to be within the area of the current distribution of humpback dolphins; Putian was identified as a new area with suitable habitat, however, it is unclear if dolphins are present. 4. The predicted locations of suitable humpback dolphin habitats provided in this study should be the focus of future research and nature reserve designs.

Mapping habitat protection priority over a marine ecoregion under information gaps

“…In the Gulf of Thailand, known occurrences of humpback dolphins and Irrawaddy dolphins were reported not only in Surat Thani–Khanom waters (Jutapruet et al., 2015, 2017), but also in the eastern and upper Gulf of Thailand (Andersen & Kinze, 2000) which were included in the likely habitats projected by MaxEnt scenarios (Figure 2). Similar consistency was also reported for Indo‐Pacific humpback dolphins in Chinese waters (Chen et al., 2020; Huang et al., 2020). MaxEnt scenarios can help to map likely habitats that are never or seldom investigated over a wide spatial range (Huang et al., 2020).…”

“…Analogous results were also reported in Chinese waters (Huang et al., 2018; Wu et al., 2017), Cambodia (Beasley & Davidson, 2007) and nearby Southeast Asian waters (Jackson‐Ricketts et al., 2020; Minton et al., 2011, 2017). Some studies used distance to river mouth as a variable to describe occurrences of marine megafauna species (Chen et al., 2020; Jackson‐Ricketts et al., 2020). Interestingly, these studies consistently indicate an environment featuring brackish and turbid waters (Jackson‐Ricketts et al., 2020; Wu et al., 2017), the estuary turbidity maxima (ETM) area (Asp et al., 2018; Wu et al., 2017).…”

Estimating the impact of climate change on the potential distribution of Indo-Pacific humpback dolphins with species distribution model

“…The basic niche that is suitable for the growth of Sousa chinensis, such as water temperature, water depth, and distance from shore, was considered in this study. The distribution of Sousa chinensis is negatively correlated with distance from shore and distance from the main estuary (Chen et al, 2020); hence, estuaries have been identified as their preferred habitat (Jefferson & Karczmarski, 2001;Chen et al, 2008;Jefferson & Smith, 2016). Environmental change induced by climate change may also affect the distributions of bait fishes and will indirectly affect Sousa chinensis distributions (Schickele et al, 2020).…”

“…A species lives on a certain environmental niche space, so the change of the dependent environment conditions may change the distribution of this species (Bellard et al, 2012;Faleiro, Nemesio & Loyola, 2018). The distributions of marine mammals have been impacted significantly by the environmental change over the past decades (Nøttestad et al, 2015;Chen et al, 2020). According to these facts, understanding how future climate change will influence species distributions is vital for the better protection of species.…”

Beware of changes: Conservation of Indo‐Pacific humpback dolphins in disturbed habitats

“…Information gaps in the habitat configuration of humpback dolphins mainly arise from an inability to survey potential distribution ranges over a wide spatial extent, both systematically and comprehensively (Huang et al, 2018, 2019), and from using unrepresentative or non‐systematic survey designs when collecting animal occurrence data (Bao et al, 2019). To bridge this information gap, SDM analysis of occurrence data and environmental characteristic layers, based on systematically designed transect surveys, has been shown to be a valid practice (Bao et al, 2019; Chen, Hong, Hao, & Gao, 2020; Huang et al, 2018, 2019). In the northern Beibu Gulf, Wu, Xu, et al (2017) qualitatively presented a distribution gradient of Indo‐Pacific humpback dolphins along the coast of Guangxi, China, based on questionnaire surveys of local ecological knowledge.…”