Abundance and distribution of delphinids in the Red Sea (Egypt)

Animal population density;Red Sea;Animal populations--Measurement;Dolphins

Costa, Marina ; Heinrich, Sonja ; Heinrich, Sonja

University:University of St Andrews

Department:Biology (School of)

关键词: Animal population density;    Red Sea;    Animal populations--Measurement;    Dolphins;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/6802/MarinaCostaPhDThesis.pdf?sequence=6&isAllowed=y

来源: DR-NTU

【 摘 要 】

Knowledge about cetaceans in the Red Sea is limited with only a handful of sporadic orspatially-limited studies carried out to date. Funded by the Italian Cooperation througha Debt-for-Nature Swap programme and carried out in collaboration with the EgyptianNGO HEPCA, this thesis presents the results from the first ever systematic vessel-basedsurveys conducted in the southern Egyptian Red Sea from 2010 to 2013 using linetransectmethodology. The main aims of the thesis were (a) to estimate cetaceanabundance, (b) to determine distribution patterns and habitat use of the cetaceanspecies, (c) to investigate movement patterns for species for which individualrecognition techniques were suitable and (d) to identify areas of conservation concernfor cetaceans with a particular focus on existing protected areas. Eight species wereidentified, of which five were commonly encountered (Stenella longirostris, S.attenuata, Tursiops truncatus, T. aduncus, and Grampus griseus) and three were rare(Pseudorca crassidens, Sousa plumbea, Balaenoptera edeni). Estimates of abundanceusing design-based line transect sampling techniques were obtained for five species: S.attenuata 10,268 (CV=0.26); S. longirostris 6,961 (CV=0.26); T. aduncus 659 (CV=0.69);T. truncatus 509 (CV=0.33), and G. griseus 367 (CV=0.37). Habitat modelling revealedthat the two Stenella species were widely distributed across the study area. Incontrast, T. truncatus was concentrated in waters around Ras Banas peninsula (inparticular Satayah offshore reef), and T. aduncus was mainly found along the coastwith possibly separate sub-populations in the northern and southern study area. G.griseus was only encountered in the southern part. The information provided in thisstudy will allow the development of a conservation strategy for the protected areasand will serve as baseline information to carry out future survey work in the Red Sea.