scholarly journals Intertidal habitat use of bottlenose dolphins (Tursiops truncatus) in Bahía San Antonio, Argentina

2017 ◽  
Vol 98 (5) ◽  
pp. 1109-1118
Author(s):  
Els Vermeulen
Keyword(s):  
Habitat Use ◽  
Intertidal Zone ◽  
Tursiops Truncatus ◽  
San Antonio ◽  
Bottlenose Dolphins ◽  
High Tide ◽  
Marine Conservation ◽  
Shallow Waters ◽  
Encounter Rate ◽  
Western Atlantic

Very little information is available on bottlenose dolphin (Tursiops truncatus) habitat use in the South-western Atlantic. It is, however, essential in understanding their ecology and to improve conservation management. In this study, habitat use of bottlenose dolphins was examined in Bahía San Antonio, an area frequented by the species. Given the large tidal amplitude and extended intertidal zone in this bay, special focus was given to the intertidal vs subtidal habitat use patterns. Bottlenose dolphins were observed in only half of the surveyed area, with on average 1 dolphin group encountered per 100 km surveyed. All dolphin groups were seen in shallow waters <10 m deep. GLM analyses showed that especially during high tide, depth had an important effect on the dolphin encounter rate, with most dolphin groups encountered in the intertidal zone. While in the intertidal zone, most dolphin groups were observed to be engaged in surface feeding activities. The presented data indicate dolphins remained in shallow waters, and moved to the intertidal zone during high tide where they appear to find feeding opportunities. This information is believed to be of high value in understanding this population's ecological needs, and essential when aiming to improve marine conservation efforts at times of increased anthropogenic pressures in the area.

Movements and habitat use of bottlenose dolphins, Tursiops truncatus, in south-eastern Brazil

2020 ◽  
Vol 100 (4) ◽  
pp. 651-662
Author(s):  
Victor Uber Paschoalini ◽  
Marcos César de Oliveira Santos
Keyword(s):  
Habitat Use ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Eastern Coast ◽  
Brazilian Coast ◽  
Preliminary Evaluation ◽  
The South ◽  
Western Atlantic ◽  
Carbon And Nitrogen ◽  
South Eastern

AbstractBottlenose dolphins (Tursiops truncatus) have been surveyed for at least two decades on the southern Brazilian coast. However, little is known about their distribution and habitat use in lower latitudes of the South-western Atlantic Ocean. Aiming to study the movements and distribution of the species along the south-eastern Brazilian coast, we made a comparison of photo-identified individuals of the species catalogued in 21 cruises conducted between 2012 and 2015. Additionally, we performed stable isotope analyses of carbon and nitrogen in skin samples (N = 35) to provide some insights of dolphin habitat use and trophic ecology through comparisons among individuals of distinct surveyed sectors (northern and southern) and sex. A total of 177 individuals were identified. Re-sightings (N = 24) occurred at intervals from 82 to 979 days at distances from 7 to 179 km. No individual was sighted in both sectors, suggesting spatial segregation. Isotopic comparisons showed no significant differences in carbon and nitrogen signatures between distinct sectors. However, ecological divergences were found when we divided the samples by gender. Wider isotopic niches were found for the northern bottlenose dolphins vs the southern ones, which could be related to temporal and spatial variation in the availability of resources, as well as possible differences in the home ranges of males and females in each region. This study represents a preliminary evaluation of ecological aspects of bottlenose dolphins along the Brazilian south-eastern coast, however, long-term studies on the feeding ecology and habitat use of this species are important to further improve our knowledge.

Environmental drivers of habitat use by common bottlenose dolphins ( Tursiops truncatus ) in the Indian River Lagoon, Florida, USA

2020 ◽  
Author(s):  
Rachael Greller ◽  
Marilyn Mazzoli ◽  
Elizabeth Titcomb ◽  
Brandy Nelson ◽  
Richard Paperno ◽  
...  
Keyword(s):  
Habitat Use ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Indian River Lagoon ◽  
Environmental Drivers ◽  
Indian River

scholarly journals Ecoregional and temporal dynamics of dugong habitat use in a complex coral reef lagoon ecosystem

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Solène Derville ◽  
Christophe Cleguer ◽  
Claire Garrigue
Keyword(s):  
Coral Reef ◽  
Habitat Use ◽  
Marine Mammals ◽  
Temporal Dynamics ◽  
New Caledonia ◽  
High Tide ◽  
Marine Species ◽  
Spatial Density ◽  
Shallow Waters ◽  
Aerial Surveys

AbstractMobile marine species display complex and nonstationary habitat use patterns that require understanding to design effective management measures. In this study, the spatio-temporal habitat use dynamics of the vulnerable dugong (Dugong dugon) were modelled from 16 satellite-tagged individuals in the coral reef lagoonal ecosystems of New Caledonia, South Pacific. Dugong residence time was calculated along the interpolated tracks (9371 hourly positions) to estimate intensity of use in three contrasting ecoregions, previously identified through hierarchical clustering of lagoon topographic characteristics. Across ecoregions, differences were identified in dugong spatial intensity of use of shallow waters, deeper lagoon waters and the fore-reef shelf outside the barrier reef. Maps of dugong intensity of use were predicted from these ecological relationships and validated with spatial density estimates derived from aerial surveys conducted for population assessment. While high correlation was found between the two datasets, our study extended the spatial patterns of dugong distribution obtained from aerial surveys across the diel cycle, especially in shallow waters preferentially used by dugongs at night/dusk during high tide. This study has important implications for dugong conservation and illustrates the potential benefits of satellite tracking and dynamic habitat use modelling to inform spatial management of elusive and mobile marine mammals.

scholarly journals Interactions between Mediterranean bottlenose dolphins (Tursiops truncatus) and gillnets off Sardinia, Italy

2006 ◽  
Vol 63 (5) ◽  
pp. 946-951 ◽  
Author(s):  
Bruno Díaz López
Keyword(s):  
Group Size ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Size Analysis ◽  
Encounter Rate ◽  
New Approach ◽  
Annual Loss ◽  
Direct Observations ◽  
Annual Estimate ◽  
Northeastern Coast

Abstract A first attempt at analysing interactions between bottlenose dolphins and gillnets along the northeastern coast of Sardinia (Italy) was conducted between October 1999 and December 2004. A new approach was used: combining interviews with fishers with boat-based direct observations and behavioural and group size analysis. Fishers on monitored boats noted 2556 days on which gillnet damage was caused by bottlenose dolphins, 68.7% of the total fishing days, with no difference between seasons. An annual estimate of the number of bottlenose dolphins caught in the gillnets was 1.47 (0.98 immatures and 0.49 adults). In all, 317 days were spent making observations at sea, of which 330.6 h were spent directly observing the dolphins. There were no changes in the distribution of daily encounter rate among seasons, group size, or number of immatures, in the presence or the absence of gillnets. However, bottlenose dolphins spent more time both in the study area and feeding when gillnets were present. The extent of the estimated bycatch is worrisome in terms of the ability of bottlenose dolphins off Sardinia to sustain such an annual loss.

scholarly journals Distribution and abundance of bottlenose dolphin (Tursiops truncatus) over the French Mediterranean continental shelf

2019 ◽  
Author(s):  
Hélène Labach ◽  
Caroline Azzinari ◽  
Maxime Barbier ◽  
Cathy Cesarini ◽  
Boris Daniel ◽  
...  
Keyword(s):  
Continental Shelf ◽  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Bottlenose Dolphins ◽  
Encounter Rate ◽  
Habitat Directive ◽  
Photo Identification ◽  
Gulf Of Lion ◽  
Capture Recapture ◽  
First Time

AbstractThe Mediterranean bottlenose dolphin (Tursiops truncatus) sub-population is listed as vulnerable by the International Union for Conservation of Nature. This species is strictly protected in France and the designation of Special Areas of Conservation (SAC) is required under the European Habitat Directive. However, little information is available about the structure, dynamic and distribution of the population in the French Mediterranean waters. We collected photo-identification data over the whole French Mediterranean continental shelf all year round between 2013 and 2015. We sighted 151 groups of bottlenose dolphins allowing the individually photo-identification of 1,060 animals. The encounter rate distribution showed the presence of bottlenose dolphins over the whole continental shelf all year round. Using capture-recapture methods, we estimated for the first time the size of the bottlenose dolphin resident population at 557 individuals (95% confidence interval: 216-872) along the French Mediterranean continental coast. Our results were used in support of the designation of a new dedicated SAC in the Gulf of Lion and provide a reference state for the bottlenose dolphin monitoring in the French Mediterranean waters in the context of the Marine Strategy Framework Directive.

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