Abstract
Knowledge of the habitat use of wildlife in highly impacted areas is essential to identify areas of biological importance and to implement appropriate conservation measures. The Arabian Gulf represents one of the most extreme marine environments and is considered one of the regions in the world with the greatest anthropogenic impact. Information on the habitat use and abundance of marine top predator species is, however, lacking, despite being a prerequisite for effective planning of conservation measures. Here, we provide novel information for the Indo-Pacific bottlenose dolphin (Tursiops aduncus) in the Arabian Gulf (Abu Dhabi, United Arab Emirates). Data from 80 daily surveys conducted between June 2014 and November 2019 were used both to assess correlates of bottlenose dolphin habitat use and relative density and to calculate mark-recapture abundance estimates. This study confirms the strong adaptability and tolerance of this top marine predator to extreme environmental conditions within a highly heterogeneous and impacted marine habitat. The observed preferences for areas with less human pressure were likely a result of the interactions of environmental factors with prey availability and human disturbance. This study also provides the first abundance estimates for a bottlenose dolphin population in the Arabian Gulf. Our findings support the call for increased marine-protected areas and the creation of transboundary conservation areas in the region. Regional connectivity should be of value to marine predators whose wide distribution and vulnerability to human activities means that alteration of their habitats can result in population declines and eventual local or regional extinctions.
Highlights
As relatively large top predators, dolphins are key component of marine ecosystems
There is a lack of information on habitat use and population abundance throughout much of the species' range, and it is likely that some bottlenose dolphin populations could be classified as "Threatened", in habitats where rapid recent economic, social, and industrial development has not been adequately compensated by conservation measures (Braulik et al 2019)
A total of 757 bottlenose dolphins were sighted on 34 different days (42.5% of the total number of daily surveys) during seven different months
Summary
As relatively large top predators, dolphins are key component of marine ecosystems. These small cetaceans fulfil ‘‘umbrella’’ and ‘‘flagship’’ criterion and are of high ecological value (Connor et al 2000). Bottlenose dolphins (Tursiops spp.), despite being widely considered some of the most adaptable of the world's cetaceans, are highly susceptible to environmental changes (Bejder et al 2006; Sprogis et al 2018; Díaz López 2019; Methion and Díaz López 2019). Due to their inshore distribution and life history characteristics (i.e., relatively large size, slow growth, late maturation, long gestation period, single births at a time, and long calving interval), bottlenose dolphins are vulnerable to a range of anthropogenic impacts such as habitat modification, overfishing, noise and chemical pollution, bycatch, and boat strikes (Díaz López 2006; Wang and Yang 2009). There is a lack of information on habitat use and population abundance throughout much of the species' range, and it is likely that some bottlenose dolphin populations could be classified as "Threatened", in habitats where rapid recent economic, social, and industrial development has not been adequately compensated by conservation measures (Braulik et al 2019)
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