Habitat preferences and evidence for niche partitioning amongst cetaceans in the waters between Gabon and Angola, eastern tropical Atlantic

2012 ◽  
Vol 92 (8) ◽  
pp. 1735-1749 ◽  
Author(s):  
Caroline R. Weir ◽  
Colin D. MacLeod ◽  
Graham J. Pierce
Keyword(s):  
Water Depth ◽  
Habitat Preferences ◽  
Principal Component ◽  
Sperm Whale ◽  
Interspecific Variation ◽  
Common Dolphin ◽  
Tropical Atlantic ◽  
Cetacean Species ◽  
Pilot Whale ◽  
Species Pairs

The habitat preferences and niches of eight cetacean species inhabiting eastern tropical Atlantic waters between Angola and Gabon (1°N–11°S latitude) were examined. A total of 2873 cetacean sightings, recorded between January 2004 and June 2009, was assigned to 10 × 10 km grid cells and linked to four ecogeographical variables (EGVs): water depth, seabed slope, sea surface temperature (SST) and relative frontal strength. Classification trees revealed that the habitat preferences (in terms of the habitats sampled) of most species were primarily determined by SST (for Bryde's whale, sperm whale, short-finned pilot whale and common dolphin) and water depth (for Risso's dolphin, bottlenose dolphin and Atlantic spotted dolphin). Seabed slope was the most important EGV describing the presence of the striped dolphin. A principal component analysis was used to compare the niches of the species with respect to the four EGVs. Nineteen species pairs (68%) differed significantly in median principal component (PC) score for the first PC axis, suggesting differences in their niche centres for that axis. Sixteen species pairs (57%) differed significantly in PC score variance suggesting differences in the niche widths along the first PC axis. Water depth and SST were the most important variables for the first PC axis. Together, these results suggest that cetacean species inhabiting the eastern tropical Atlantic exhibit interspecific variation in their habitat preferences, and so differ in the niches that they occupy. These differences are most likely related to variation in prey species and foraging strategy.

The cetaceans of Aruba, southern Caribbean

2013 ◽  
Vol 94 (6) ◽  
pp. 1161-1174 ◽  
Author(s):  
Jolanda A. Luksenburg
Keyword(s):  
Killer Whale ◽  
Sperm Whale ◽  
Common Dolphin ◽  
Physeter Macrocephalus ◽  
Cetacean Species ◽  
Additional Species ◽  
Pilot Whale ◽  
Stenella Frontalis ◽  
Spotted Dolphin ◽  
Delphinus Capensis

Aruba is one of the most densely populated islands in the Caribbean. However, very little is known about its cetaceans. In 2010 and 2011, a total of 19721 km (1686 h) boat-based surveys over nearshore transects resulted in 117 positively-identified sightings comprising eight species. New records are also added for one of three previously-documented species. Five additional species were documented from strandings or reports by others. This brings the total number of cetacean species identified in Aruban waters to 16, of which nine are authenticated here for the first time. Atlantic spotted dolphin (Stenella frontalis (N = 59) and bottlenose dolphin (Tursiops truncatus) (N = 33) were the most frequently observed species, with sightings of both year-round, followed by spinner dolphin (S. longirostris) and false killer whale (Pseudorca crassidens). Additional species recorded are pantropical spotted dolphin (S. attenuata), striped dolphin (S. coeruleoalba), common dolphin (Delphinus capensis), rough-toothed dolphin (Steno bredanensis), short-finned pilot whale (Globicephala macrorhynchus), killer whale (Orcinus orca), Risso's dolphin (Grampus griseus), humpback whale (Megaptera novaeangliae), Bryde's/Eden's whale (Balaenoptera brydei/edeni), sperm whale (Physeter macrocephalus) and an unidentified beaked whale (Mesoplodon sp.). All cetaceans were sighted within 22 km of the coast in relatively shallow waters. Sighting rate was low (0.69 cetacean sightings per 100 km). Sightings of calves and neonates indicate that Aruba may be a nursing or breeding area for some species. The presence of several species of cetaceans in Aruba's coastal waters year-round indicates that status and threat assessments are needed to protect them.

Encounter rates of cetaceans in the Mediterranean Sea and contiguous Atlantic area

2010 ◽  
Vol 90 (8) ◽  
pp. 1589-1599 ◽  
Author(s):  
Oliver Boisseau ◽  
Claire Lacey ◽  
Tim Lewis ◽  
Anna Moscrop ◽  
Magnus Danbolt ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Sperm Whale ◽  
Common Dolphin ◽  
Cetacean Species ◽  
Pilot Whale ◽  
Encounter Rates ◽  
Striped Dolphin ◽  
Common Bottlenose Dolphin ◽  
The Mediterranean ◽  
First Time

A series of visual–acoustic surveys were carried out in the Mediterranean Sea between 2003 and 2007 from RV ‘Song of the Whale’. Almost 21,000 km of trackline were surveyed between the longitudes of 14°W and 36°E with an emphasis on regions with low survey effort. Survey tracklines were designed to provide even coverage probability with random start points. Ten cetacean species were positively identified (sperm whale, fin whale, Cuvier's beaked whale, false killer whale, long-finned pilot whale, Risso's dolphin, common bottlenose dolphin, rough-toothed dolphin, striped dolphin and short-beaked common dolphin). Several of these species, plus sei whale and harbour porpoise, were also encountered in the Atlantic contiguous area (the entrance waters of the Mediterranean between the Iberian Peninsula and north-west Morocco). These surveys expand and clarify the known distributions of cetaceans within the Mediterranean basin. New species documented from Libyan waters include sperm whale, striped dolphin and rough-toothed dolphin. False killer whales and rough-toothed dolphins were documented for the first time off Cyprus. Live harbour porpoises were seen for the first time on Morocco's Atlantic seaboard. It is suggested that the status of rough-toothed dolphins in the Mediterranean be revised from visitor to regular species. Substantial new information on encounter rates is now available for the planning of a basin-wide systematic survey of cetaceans within the Mediterranean Sea and contiguous Atlantic waters.

Trends in cetacean sightings along the Galician coast, north-west Spain, 2003–2007, and inferences about cetacean habitat preferences

2010 ◽  
Vol 90 (8) ◽  
pp. 1547-1560 ◽  
Author(s):  
Graham J. Pierce ◽  
Mara Caldas ◽  
Jose Cedeira ◽  
M. Begoña Santos ◽  
Ángela Llavona ◽  
...  
Keyword(s):  
Habitat Use ◽  
Continental Shelf ◽  
Bottlenose Dolphins ◽  
Habitat Preferences ◽  
Common Dolphin ◽  
Pilot Whale ◽  
Important Species ◽  
North West ◽  
Blue Whiting ◽  
Common Dolphins

Since mid-2003, systematic monthly sightings surveys for cetaceans have been carried out in Galicia (north-west Spain) from observation points around the coastline, with the aim of providing baseline data on cetacean distribution and habitat use to underpin future conservation measures. Here we summarize results for September 2003 to October 2007. The most frequently recorded species were the bottlenose dolphin (Tursiops truncatus, seen during 10.7% of observation periods), common dolphin (Delphinus delphis, 3.7%), harbour porpoise (Phocoena phocoena, 1.6%), Risso's dolphin (Grampus griseus, 0.4%) and short-finned pilot whale (Globicephala melas, 0.2%). The three most common species showed different distribution patterns along the coast. In terms of habitat preferences, bottlenose dolphins were seen to be associated with more productive areas (areas with higher chlorophyll-a concentrations) where the continental shelf was wider while both common dolphins and harbour porpoises were seen most frequently in less productive areas where the continental shelf is narrowest. Possible reasons for differences in habitat use include differing diets. In Galician waters, all three main cetacean species feed primarily on fish that are common in shelf waters, and in the case of blue whiting (the most important species in the stomach contents of common and bottlenose dolphins) abundant also on the slope. All three cetaceans feed on blue whiting while scad is important in diets of common dolphin and porpoise. It is also possible that porpoises do not use areas frequented by bottlenose dolphins in order to avoid aggressive interactions. Retrospective evaluation of the sampling regime, using data from the 2500 observation periods during 2003–2007 suggests that the overall sightings rates for all species (taking into account observation time and between-site travel time) would be higher if average observation duration was increased to at least 40 minutes. On the other hand, confidence limits on sightings rates stabilized after around 1000 observation periods, suggesting that the number of sites visited or the frequency of visits could be substantially reduced.

Summer distribution and relative abundance of cetacean populations off north-west Scotland

2003 ◽  
Vol 83 (5) ◽  
pp. 1187-1192 ◽  
Author(s):  
K. Macleod ◽  
M.P. Simmonds ◽  
E. Murray
Keyword(s):  
Relative Abundance ◽  
Sperm Whale ◽  
Abundant Species ◽  
Line Transect ◽  
Migration Route ◽  
Common Dolphin ◽  
Physeter Macrocephalus ◽  
Pilot Whale ◽  
North West ◽  
Line Transect Survey

A line transect survey was conducted in July/August 1998 to investigate the distribution and abundance of cetaceans off north-west Scotland. Over 2156.5 km of survey effort, 304 sightings were recorded of which 184 were identified to species. Nine species were identified: Atlantic white-sided dolphin Lagenorhynchus acutus, fin whale Balaenoptera physalus, sei whale Balaenoptera borealis, long-finned pilot whale Globicephala melas, sperm whale Physeter macrocephalus, common dolphin Delphinus delphis, harbour porpoise Phocoena phocoena, white beaked dolphin Lagenorhynchus albirostris and Risso's dolphin Grampus griseus. The Atlantic white-sided dolphin was the most relatively abundant species. The relative abundance of large whales and dolphins was greatest in the Faroe–Shetland Channel. The continental slopes of this area are undergoing development by oil industries and concerns have been raised about the potential impacts of these activities on cetaceans. These waters are used year-round by cetaceans and provide feeding and breeding grounds and are a migration route for large whales.

scholarly journals A note on concentrations of metals in cetaceans from southern Africa

1999 ◽  
pp. 177-194
Author(s):  
John Henry
Keyword(s):  
Sperm Whale ◽  
Common Dolphin ◽  
Physeter Macrocephalus ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Right Whales ◽  
Beaked Whales ◽  
Common Dolphins ◽  
Hourglass Dolphin ◽  
Pygmy Sperm Whale

Concentrations of zinc, copper, cadmium, mercury and lead were measured by atomic absorption spectrophotometry in samples of the brain, kidney , liver and muscle tissue from 178 individuals of 323 different cetacean species (4 right whales - Eubalaena australis, 2 pygmy right whales - Caperea marginara, 3 minke whales - Balaenoptera acutorostrata, 3 Bryde's whales - B. edeni, 1 humpback whale - Megaptera novaeangliae, 1 sperm whale - Physeter macrocephalus, 11 pygmy sperm whale - Kogia breviceps, 6 dwarf sperm whales - K. simus, 1 southern bottlenose whale - Hyperoodon planifrons, 1 Cuvier's beaked whale - Ziphius cavirostris, 9 Blainville's beaked whales - Mesoplodon densirostris, 5 strap-tooth whales - M. layardii, 2 True's beaked whales - M. mirus, 3 long-finned pilot whales - Globicephala me/as, 30 Risso's dolphins - Grampus griseus, 12 bottlenose dolphins - Tursiops truncatus, 5 striped dolphins - Stenella coeruleoalba, 1 pantropical spotted dolphin - S. attenuata, 1 hump-backed dolphin - Sousa chinensis, 21 dusky dolphins - Lagenorhynchus obscurus, 1 hourglass dolphin - L. cruciger, 12 Heaviside's dolphins - Cephalorhynchus heavisidii and 43 common dolphins - Delphinus delphis). All but the hourglass dolphin were strandings or animals taken incidental to fishing operations or under scientific permit in coastal waters of South Africa or Namibia. Highest concentrations of Zn, Cu and Hg were generally found in the liver and of Cd in the kidney. Comparisons of animals pre-and post puberty indicated accumulation of hepatic mercury in the pygmy sperm whale, Risso's dolphin, dusky dolphin and common dolphin. Loss of a metal (zinc) after puberty was only shown in the common dolphin. No individual analyses exceeded proposed (human) tolerance limits for hepatic mercury and hepatic or renal cadmium

scholarly journals The primary visual cortex of Cetartiodactyls: organization, cytoarchitectonics and comparison with perissodactyls and primates

2021 ◽  
Author(s):  
Jean-Marie Graïc ◽  
Antonella Peruffo ◽  
Livio Corain ◽  
Livio Finos ◽  
Enrico Grisan ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Calcium Binding ◽  
Sperm Whale ◽  
Marine Species ◽  
Lateral Position ◽  
Cetacean Species ◽  
Pilot Whale ◽  
Fin Whale ◽  
Binocular Field

AbstractCetartiodactyls include terrestrial and marine species, all generally endowed with a comparatively lateral position of their eyes and a relatively limited binocular field of vision. To this day, our understanding of the visual system in mammals beyond the few studied animal models remains limited. In the present study, we examined the primary visual cortex of Cetartiodactyls that live on land (sheep, Père David deer, giraffe); in the sea (bottlenose dolphin, Risso’s dolphin, long-finned pilot whale, Cuvier’s beaked whale, sperm whale and fin whale); or in an amphibious environment (hippopotamus). We also sampled and studied the visual cortex of the horse (a closely related perissodactyl) and two primates (chimpanzee and pig-tailed macaque) for comparison. Our histochemical and immunohistochemical results indicate that the visual cortex of Cetartiodactyls is characterized by a peculiar organization, structure, and complexity of the cortical column. We noted a general lesser lamination compared to simians, with diminished density, and an apparent simplification of the intra- and extra-columnar connections. The presence and distribution of calcium-binding proteins indicated a notable absence of parvalbumin in water species and a strong reduction of layer 4, usually enlarged in the striated cortex, seemingly replaced by a more diffuse distribution in neighboring layers. Consequently, thalamo-cortical inputs are apparently directed to the higher layers of the column. Computer analyses and statistical evaluation of the data confirmed the results and indicated a substantial correlation between eye placement and cortical structure, with a markedly segregated pattern in cetaceans compared to other mammals. Furthermore, cetacean species showed several types of cortical lamination which may reflect differences in function, possibly related to depth of foraging and consequent progressive disappearance of light, and increased importance of echolocation.

scholarly journals Cetacean strandings along the German North Sea coastline 1604–2017

2021 ◽  
pp. 1-20
Author(s):  
Carl Christian Kinze ◽  
Richard Czeck ◽  
Helena Herr ◽  
Ursula Siebert
Keyword(s):  
North Sea ◽  
Native Species ◽  
Sperm Whale ◽  
Beluga Whale ◽  
Delphinapterus Leucas ◽  
Common Dolphin ◽  
Physeter Macrocephalus ◽  
Pilot Whale ◽  
Stenella Coeruleoalba ◽  
Fin Whale

Abstract The occurrence of 19 cetacean species along the German North Sea coastline as well as the lower reaches of the major rivers discharging into the German Bight is reviewed for the period 1604–2017 based on records of dead animals, either stranded dead or put to death. The harbour porpoise (Phocoena phocoena) is considered the most abundant and only native species in German coastal and riverine waters. Based on written sources its presence can be traced back to at least 1651, although with statistical data only available from 1990. Finds of further 18 species have been documented: white-beaked dolphin (Lagenorhynchus albirostris), bottlenose dolphin (Tursiops truncatus), Atlantic white-sided dolphin (Lagenorhynchus acutus), common dolphin (Delphinus delphis), striped dolphin (Stenella coeruleoalba), Risso's dolphin (Grampus griseus), long-finned pilot whale (Globicephala melas), killer whale (Orcinus orca), beluga whale (Delphinapterus leucas), narwhal (Monodon monoceros), Sowerby's beaked whale (Mesoplodon bidens), northern bottlenose whale (Hyperoodon ampullatus), sperm whale (Physeter macrocephalus), minke whale (Balaenoptera acutorostrata), sei whale (Balaenoptera borealis), fin whale (Balaenoptera physalus), blue whale (Balaenoptera musculus) and humpback whale (Megaptera novaeangliae). This review corrects several false species assignments earlier introduced in literature based on incorrect scientific or ambiguous German vernacular names and recovers lost records of beluga whale, northern bottlenose whale, sperm whale and fin whale.

scholarly journals Cetaceans observed in Suriname and adjacent waters

2015 ◽  
Vol 10 (1) ◽  
pp. 2-19 ◽  
Author(s):  
Marijke Nita De Boer
Keyword(s):  
Bottlenose Dolphin ◽  
Sperm Whale ◽  
Seismic Survey ◽  
Marine Biodiversity ◽  
Common Dolphin ◽  
Cetacean Species ◽  
Spotted Dolphin ◽  
Common Bottlenose Dolphin ◽  
Delphinus Capensis ◽  
Guiana Dolphin

Very little information exists about the cetaceans in the Guianas: Suriname and its neighboring countries Guyana and French Guiana. During a dedicated cetacean survey carried out from a geophysical seismic survey vessel in the offshore waters of Suriname (May-September 2012), the occurrence of 13 cetacean species was documented and of those, 11 were newly documented for this area. The species observed by the author included sperm whale (Physeter macrocephalus), Bryde’s whale (Balaenoptera edeni), false killer whale (Pseudorca crassidens), melon-headed whale (Peponocephala electra), roughtoothed dolphin (Steno bredanensis), long-beaked common dolphin (Delphinus capensis), Fraser’s dolphin (Lagenodelphis hosei), pantropical spotted dolphin (Stenella attenuata) and spinner dolphin (Stenella longirostris). During transit to the survey area (Trinidad to Suriname) incidental sightings were recorded which included common bottlenose dolphin (Tursiops truncatus) off Trinidad, Stenella sp. off Guyana and Guiana dolphin (Sotalia guianensis) at the entrance of the Suriname River. Opportunistic records originating from the periods December 2008-March 2009 and August-October 2012 were forwarded to the author. These records included common bottlenose dolphin, Atlantic spotted dolphin (Stenella frontalis) and short-finned pilot whale (Globicephala macrorhynchus). There is a growing need to identify critical areas for marine biodiversity conservation, both locally and regionally. This paper describes the general occurrence of the cetacean community encountered in Suriname waters in summer. The study revealed that the offshore cetacean community in Suriname is best described as primarily a tropical community, dominated by odontocetes (dolphins and sperm whales). Although the species diversity was relatively high, the overall cetacean relative abundance index (number of animals per 100km effort) was low, which is consistent for tropical equatorial offshore waters. Apart from the sperm whale and the Guiana dolphin, all the other species recorded represent new species records for Suriname. It is recommended that more continuous monitoring in different seasons be carried out in order to gain a better understanding of the occurrence, distribution and status of the different cetacean species within the region. 

scholarly journals Endoscopic Study of the Oral and Pharyngeal Cavities in the Common Dolphin, Striped Dolphin, Risso’s Dolphin, Harbour Porpoise and Pilot Whale: Reinforced with Other Diagnostic and Anatomic Techniques

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1507
Author(s):  
Álvaro García de los Ríos y Loshuertos ◽  
Marta Soler Laguía ◽  
Alberto Arencibia Espinosa ◽  
Francisco Martínez Gomariz ◽  
Cayetano Sánchez Collado ◽  
...  
Keyword(s):  
Oral Cavity ◽  
Common Dolphin ◽  
Resonance Imaging ◽  
Pilot Whale ◽  
Anatomical Structures ◽  
Vascular Plexus ◽  
Endoscopic Study ◽  
Main Technique ◽  
The Common ◽  
Magnetic Resonance Imaging Mri

In this work, the fetal and newborn anatomical structures of the dolphin oropharyngeal cavities were studied. The main technique used was endoscopy, as these cavities are narrow tubular spaces and the oral cavity is difficult to photograph without moving the specimen. The endoscope was used to study the mucosal features of the oral and pharyngeal cavities. Two pharyngeal diverticula of the auditory tubes were discovered on either side of the choanae and larynx. These spaces begin close to the musculotubaric channel of the middle ear, are linked to the pterygopalatine recesses (pterygoid sinus) and they extend to the maxillopalatine fossa. Magnetic Resonance Imaging (MRI), osteological analysis, sectional anatomy, dissections, and histology were also used to better understand the function of the pharyngeal diverticula of the auditory tubes. These data were then compared with the horse’s pharyngeal diverticula of the auditory tubes. The histology revealed that a vascular plexus inside these diverticula could help to expel the air from this space to the nasopharynx. In the oral cavity, teeth remain inside the alveolus and covered by gums. The marginal papillae of the tongue differ in extension depending on the fetal specimen studied. The histology reveals that the incisive papilla is vestigial and contain abundant innervation. No ducts were observed inside lateral sublingual folds in the oral cavity proper and caruncles were not seen in the prefrenular space.

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