Πληθυσμιακή δομή, κατανομή και αφθονία ειδών: ζωνοδέλφινο Stenella coeculeoalba, κοινό δελφίνι Delphinus delphis και φυσητήρας Physeter macrocephalus σε περιοχές της Μεσογείου

• Main Authors: Karamitros, Grigorios, Καραμήτρος, Γρηγόριος
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: University of Thessaly (UTH) 2022
• Subjects: Zωνοδέλφινο; Kοινό δελφίνι; Φυσητήρας; Μοντέλο Επιφανειακή Πυκνότητας; Δειγματοληψία Αποστάσεων; Striped dolphin; Common dolphin; Sperm whale; Density Surface Models; Distance sampling; Γεωεπιστήμες και Επιστήμες Περιβάλλοντος; Φυσικές Επιστήμες; Επιστήμες περιβάλλοντος; Άλλες Γεωπονικές Επιστήμες; Γεωπονικές Επιστήμες και Κτηνιατρική; Earth and Related Environmental Sciences; Natural Sciences; Environmental Sciences; Other Agricultural Sciences; Agricultural and Veterinary Sciences; North Atlantic; Physeter macrocephalus
• Online Access: http://hdl.handle.net/10442/hedi/53466; https://doi.org/10.12681/eadd/53466

The study of marine mammal distribution in a wide research area such as Mediterranean Sea, consists a vital procedure in species conservation focusing in highlighting on critical habitats. The understanding of population patterns can be improved significantly with the use of spatial models with environmental covariates. Density Surface Models (DSM) can contribute significantly providing predictions about spatial distribution of marine mammals. These models, require the combination of Geographical Information Systems (GIS) in addition with Generalized Additive Models (GAMs) providing a better understanding of biotic and environmental factors which affect the marine mammal distribution. In this thesis investigated data of transect line Distance Sampling (DS) were collected for seven years with a small catamaran boat. The data were the visual observation for species striped dolphin (Stenella coeruleoalba) and common dolphin (Delphinus delphis) and the visual and passive acoustic observations for sperm whale (Physeter macrocephalus). The study area includes a major part of Mediterranean Sea, as well as a part of contiguous area of North Atlantic Ocean. For model fitting, a series of explanatory factors was investigated such as sea surface temperature, chlorophyll concentrations, depth, slope of sea floor, distance from coast and distance of specific isobaths contours. The striped dolphin was found to be the dominant species with extensive distribution in the study area, while its abundance seems to be affected both by the depth and the distance from the isobaths of 200 m. The distribution of the common dolphin appeared to be influenced by factors, longitude and latitude as well as chlorophyll concentration. The depth, the distance from coast and the chlorophyll concentration were found to influence the distribution of sperm whale, proposing the Greek Trench as an important zone for the species in the Mediterranean Sea. Important areas for the species were also found in the marine areas of Cape Verde, the Canary ...