Influence of environmental factors on small cetacean distribution in the Spanish Mediterranean

2008 ◽  
Vol 88 (6) ◽  
pp. 1185-1192 ◽  
Author(s):  
A. Gómez de Segura ◽  
P.S. Hammond ◽  
J.A. Raga
Keyword(s):  
Linear Models ◽  
Bottlenose Dolphins ◽  
Chlorophyll Concentration ◽  
Spatial Models ◽  
Distribution Models ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Striped Dolphin ◽  
Environmental Features ◽  
Risso's Dolphin

Habitat distribution models are one of the most up to date methods to study the habitat usage of wildlife populations. They allow animal distribution to be related to environmental features and also the prediction of the distribution of animals based on this relationship. Seasonal aerial surveys were conducted in central Spanish Mediterranean waters from June 2000 to March 2003 to obtain information on the distribution of cetacean species. Data from the three most common cetacean species (striped dolphin, Stenella coeruleoalba, bottlenose dolphin, Tursiops truncatus, and Risso's dolphin, Grampus griseus) were related, using generalized linear models, to local environmental features: depth, slope, sea surface temperature and chlorophyll concentration. For bottlenose dolphins, no significant relationship was found with any covariate and no dolphins were observed in waters greater than 1000 m. The distribution of both striped and Risso's dolphin was significantly related to depth. The striped dolphin showed a preference for waters between 900 and 1500 m deep and Risso's dolphin for waters more than 1500 m deep. In addition, for the latest two species, maps of distribution were predicted by means of the spatial models. The areas of higher probabilities of occurrence coincide to a large extent with the marine protected areas previously proposed for the conservation of oceanic cetacean species.

scholarly journals Determinants of lungworm specificity in five cetacean species in the western Mediterranean

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rachel Pool ◽  
Clara Romero-Rubira ◽  
Juan Antonio Raga ◽  
Mercedes Fernández ◽  
Francisco Javier Aznar
Keyword(s):  
Bottlenose Dolphins ◽  
Parasite Burden ◽  
Western Mediterranean ◽  
Host Size ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Species Similarity ◽  
Pilot Whales ◽  
Common Dolphins ◽  
Prey Overlap

Abstract Background Current data about Pseudaliidae show contrasting patterns of host specificity between congeneric species. We investigated how both contact and compatibility between hosts and parasites contributed to the patterns of lungworm infection observed in a community of five species of cetaceans in the western Mediterranean. Methods The lungs of 119 striped dolphins Stenella coeruleoalba, 18 bottlenose dolphins Tursiops truncatus, 7 Risso’s dolphins Grampus griseus, 7 long-finned pilot whales Globicephala melas, and 6 common dolphins Delphinus delphis were analysed for lungworms. Parasites were identified by morphology and analysis of ITS2 sequences using both maximum likelihood and Bayesian inference methods. Body length was used as a proxy for lungworm species fitness in different hosts and compared with Kruskal-Wallis tests. Infection parameters were compared between cetacean species using Fisher’s exact tests and Kruskal-Wallis tests. Phylogenetic specificity was explored by collating the overall lungworm species prevalence values in hosts from previous surveys in various localities. To explore the relative importance of vertical and horizontal transmission, Spearman’s rank correlation was used to look for an association between host size and lungworm burden. A Mantel test was used to explore the association between lungworm species similarity and prey overlap using dietary data. Results Halocercus delphini had higher infection levels in striped dolphins and common dolphins; Stenurus ovatus had higher infection levels in bottlenose dolphins; and Stenurus globicephalae had higher infection levels in long-finned pilot whales. These results are congruent with findings on a global scale. Morphometric comparison showed that the larger nematodes were found in the same host species that had the highest parasite burden. Lungworms were found in neonatal striped dolphins and a Risso’s dolphin, and there was a weak but significant correlation between host size and parasite burden in striped dolphins and bottlenose dolphins. There was also a weak but significant association between prey overlap and lungworm species similarity. Conclusions Data indicate that phylogenetic specificity has an important role in governing host–parasite associations, as indicated by the higher infection levels and larger nematode size in certain hosts. However, diet can also influence infection patterns in these preferred hosts and contribute to less severe infections in other hosts.

An insight into the status of the striped dolphins, Stenella coeruleoalba, of the southern Tyrrhenian Sea

2007 ◽  
Vol 87 (5) ◽  
pp. 1321-1326 ◽  
Author(s):  
Caterina Maria Fortuna ◽  
Simonepietro Canese ◽  
Michela Giusti ◽  
Eletta Revelli ◽  
Pierpaolo Consoli ◽  
...  
Keyword(s):  
Line Transect ◽  
Tyrrhenian Sea ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Striped Dolphin ◽  
The Status ◽  
Southern Tyrrhenian Sea ◽  
By Catch ◽  
Aeolian Archipelago ◽  
Insight Into

Drift-nets are known to result in high incidental catches of some cetacean species. Despite a UN moratorium on their use in the high seas and a ban in the Mediterranean by all European Union countries, including Italy (EC Reg. 1239/98), some fisheries continue to operate illegally. In 2002 and 2003 three line-transect surveys were conducted in the southern Tyrrhenian Sea around the Aeolian archipelago. These transects were designed to assess the presence, distribution and population size of cetacean species likely to be affected by accidental captures in this area. Data were only sufficient to estimate abundance for the striped dolphin. The best estimate (and first such estimate for this area) was 4030 individuals (CV=0.30, 95% CI=2239–7253) for May 2003. A rough estimate of striped dolphin by-catch, based on floating carcases, was calculated as 36 by-caught animals over a period of 12 days (CV=0.58, 95% CI=11–113). These results, although approximate, are a cause for concern. Conservation and management implications of the results are discussed.

scholarly journals Cetacean mortality due to interactions with fisheries and marine litter ingestion in the Croatian part of the Adriatic Sea from 1990 to 2019

2021 ◽  
Vol 91 (2) ◽  
pp. 189-206
Author(s):  
Martina Đuras ◽  
◽  
Ana Galov ◽  
Kim Korpes ◽  
Magdalena Kolenc ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Bottlenose Dolphins ◽  
Surveillance Program ◽  
Cetacean Species ◽  
Term Survival ◽  
Stenella Coeruleoalba ◽  
Marine Litter ◽  
Surveillance Programs ◽  
Fisheries Interactions

Various anthropogenic threats negatively influence the survival of cetaceans in all world seas. Thanks to a long-running marine mammal surveillance program, we are able to report the results of a detailed analysis of the influence of cetacean-fisheries interactions and marine litter ingestion on cetacean mortality in the Croatian part of the Adriatic Sea over the last three decades. The total number of dead cetaceans was 459, and included 334 bottlenose dolphins (Tursiops truncatus), 40 striped dolphins (Stenella coeruleoalba), ten Risso’s dolphins (Grampus griseus), six Cuvier’s beaked whales (Ziphius cavirostris) and four fin whales (Balaenoptera physalus). Three hundred of them were examined postmortally. Cetacean-fisheries interaction occurred frequently in the Adriatic Sea, being detected in 96 (20.9%) of the recorded cases. Bycatch was the most abundant cetacean-fisheries interaction, with 66 (14.4%) cases recorded. Good nutritional condition and evidence of recent feeding were the most common findings recorded in bycatch cases, followed by persistent froth in the airways, edematous lungs, bruises and an amputated fluke or tail. Cetacean-fisheries interactions other than bycatch affected 30 animals and included larynx strangulations, long-term tail entanglement and fishing gear in the stomach. Ingestion of marine litter that was not related to fisheries was recorded in four animals. This study reveals the considerable negative anthropogenic influence on cetaceans in the Adriatic Sea, especially the bottlenose dolphin that is considered to be the most numerous cetacean species therein, and demonstrates the need for the urgent development of a cetacean bycatch reduction program. Finally, it also shows the importance of sustaining national surveillance programs to gain scientifically based knowledge important for cetacean protection and prospects for their long-term survival.

scholarly journals Heterogeneity of myoglobin distribution in the locomotory muscles of five cetacean species

2001 ◽  
Vol 204 (2) ◽  
pp. 209-215 ◽  
Author(s):  
L.K. Polasek ◽  
R.W. Davis
Keyword(s):  
Marine Mammals ◽  
Killer Whale ◽  
Bottlenose Dolphins ◽  
Spectrophotometric Analysis ◽  
Storage Site ◽  
Cetacean Species ◽  
Striped Dolphin ◽  
Contour Maps ◽  
False Killer Whale ◽  
Deep Water Species

Myoglobin is an important storage site for oxygen in the swimming muscles of diving marine mammals. However, little is known about its distribution within muscles since previous studies have relied on single samples. The goal of this study was to determine the distribution of myoglobin within the swimming muscles of five species of cetacean: dusky dolphin, false killer whale, striped dolphin, humpbacked dolphin and bottlenose dolphin. The entire dorsal (epaxial) and ventral (hypaxial) swimming muscles were removed from each animal and weighed. Transverse sections were taken from the cranial, middle and caudal regions of each muscle and sampled along a circular grid with a minimum of 30 sites per section. Spectrophotometric analysis was used to measure the myoglobin concentration of each sample. Contour maps of myoglobin concentration were made for each transverse section. Myoglobin concentration was found to be non-uniformly distributed within the muscle. The interior of the muscle lying closest to the vertebrae showed a significantly higher (11 %) mean myoglobin concentration than the exterior of the muscle for all five species. In the epaxial muscles, the mean myoglobin concentration was significantly higher in the caudal region closest to the flukes. The two deep-water species (false killer whale and striped dolphin) had significantly higher myoglobin concentrations than the three species (dusky, humpbacked and bottlenose dolphins) that occur in shallow, coastal waters. These results show that myoglobin is not homogeneously distributed in the locomotory muscle of cetaceans and that levels may be highest in those areas that produce greater force and consume more oxygen during aerobic swimming. Enhancing oxygen stores in those areas of the muscle that work the hardest would theoretically lengthen the aerobic dive limit of the animal during submerged swimming.

Host specificity ofOschmarinella rochebruniandBrachycladium atlanticum(Digenea: Brachycladiidae) in five cetacean species from western Mediterranean waters

2010 ◽  
Vol 85 (1) ◽  
pp. 12-19 ◽  
Author(s):  
P. Mateu ◽  
J.A. Raga ◽  
F.J. Aznar
Keyword(s):  
Host Species ◽  
Bottlenose Dolphins ◽  
Western Mediterranean ◽  
Its2 Region ◽  
Single Individual ◽  
Common Dolphin ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
Pilot Whales ◽  
Common Dolphins

AbstractWe investigated patterns of specificity of liver flukes (fam. Brachycladiidae) in a community of cetaceans from the western Mediterranean. The liver and pancreas of 103 striped dolphins,Stenella coeruleoalba, 18 Risso's dolphins,Grampus griseus, 14 bottlenose dolphins,Tursiops truncatus, 8 common dolphins,Delphinus delphis, and 5 long-finned pilot whales,Globicephala melas, were analysed for brachycladiid species. Two species were found:Oschmarinella rochebruniin striped dolphins (prevalence (P): 61.2%; mean intensity (MI) (95% CI): 34.2 (25.7–45.6)), andBrachycladium atlanticumin striped dolphins (P: 39.8%; MI: 7.1 (4.8–13.1)) and a single individual of common dolphin (P: 12.5%; intensity: 19), which represents a new host record. A molecular analysis using the internal transcribed spacer 2 (ITS2) region of the rDNA gene confirmed that specimens ofB. atlanticumwere conspecific regardless of host species. Available dietary data suggest that Risso's dolphins, bottlenose dolphins and long-finned pilot whales would contact rarely, if at all, the infective stages ofO. rochebruniandB. atlanticum. Neither the prevalence nor the mean abundance ofB. atlanticumdiffered significantly between striped and common dolphins, but a principal component analysis using seven morphometric variables indicated that specimens collected from the common dolphin were stunted. These worms also had fewer eggs compared with specimens typically found in striped dolphins, although the size of the eggs was similar in both host species. Dwarfism and low fecundity have typically been found in helminths infecting unusual host species, and might reflect the lower compatibility ofB. atlanticumfor common dolphins. In summary, bothO. rochebruniandB. atlanticumappear to exhibit a narrow specificity for striped dolphins in the western Mediterranean.

Cetacean stranding and diet analyses in the North Aegean Sea (Greece)

2017 ◽  
Vol 98 (5) ◽  
pp. 1011-1028 ◽  
Author(s):  
C.B. Milani ◽  
A. Vella ◽  
P. Vidoris ◽  
A. Christidis ◽  
E. Koutrakis ◽  
...  
Keyword(s):  
Bottlenose Dolphins ◽  
Aegean Sea ◽  
Cetacean Species ◽  
Stenella Coeruleoalba ◽  
The North ◽  
Aegean Islands ◽  
North Aegean ◽  
Diet Analyses ◽  
North Aegean Sea ◽  
Common Dolphins

Cetacean stranding reports in the North Aegean Sea were recorded since 1998 from Strimonikos Gulf in Chalkidiki up to Alexandroupoli on the Turkish border and in a few northern Aegean islands. On site, the specimens were examined to identify species, gender, approximate age and, when possible, cause for stranding. A total of 26 filled stomachs of five cetacean species collected since 2002 were analysed: bottlenose dolphinsTursiops truncatus(N = 8), common dolphinsDelphinus delphis(N = 8), harbour porpoisesPhocoena phocoena(N = 5), striped dolphinsStenella coeruleoalba(N = 4) and Risso's dolphinsGrampus griseus(N = 1). From the analysed stomachs it was found that the bottlenose dolphins fed mainly on snake blennyOphidion barbatum(34%), bogueBoops boops(22%) and round sardinellaSardinella aurita(13%); common dolphins on round sardinella (17%), picarelsSpicaraspp. (10%) and Cocco's lantern fishLobianchia gemellaris(9%); harbour porpoises on Gobidae (four-spotted gobyDeltentosteus quadrimaculatus41% and black gobyGobius niger37%) and round sardinella (7%); striped dolphins on Myctophydae (Madeira lantern fishCeratoscopelus maderensis51%), and on Pfeffer's enople squidAbraliopsis morisii(10%) and bogue (8%); and Risso's dolphin exclusively on Teuthidae (31%), the umbrella squidHistioteuthis bonellii(30%) and the reverse jewel squidH. reversa(14%). The present work represents the first attempt to investigate the diet up to species level for several cetaceans in Greek waters and for harbour porpoises stranded in the Mediterranean Sea.

Marine mammals are natural hosts of Oceanivirga salmonicida, a bacterial pathogen of Atlantic salmon

2020 ◽  
Vol 139 ◽  
pp. 161-174
Author(s):  
R Palmer ◽  
GTA Fleming ◽  
S Glaeser ◽  
T Semmler ◽  
A Flamm ◽  
...  
Keyword(s):  
16S Rrna ◽  
Atlantic Salmon ◽  
16S Rrna Gene ◽  
Marine Mammals ◽  
Rrna Gene ◽  
Bacterial Disease ◽  
Common Dolphin ◽  
Stenella Coeruleoalba ◽  
Striped Dolphin ◽  
Natural Hosts

During 1992 and 1993, a bacterial disease occurred in a seawater Atlantic salmon Salmo salar farm, causing serious mortalities. The causative agent was subsequently named as Oceanivirga salmonicida, a member of the Leptotrichiaceae. Searches of 16S rRNA gene sequence databases have shown sequence similarities between O. salmonicida and uncultured bacterial clones from the digestive tracts of marine mammals. In the current study, oral samples were taken from stranded dolphins (common dolphin Delphinus delphis, striped dolphin Stenella coeruleoalba) and healthy harbour seals Phoca vitulina. A bacterium with growth characteristics consistent with O. salmonicida was isolated from a common dolphin. The isolate was confirmed as O. salmonicida, by comparisons to the type strain, using 16S rRNA gene, gyrB, groEL, and recA sequence analyses, average nucleotide identity analysis, and MALDI-TOF mass spectrometry. Metagenomic analysis indicated that the genus Oceanivirga represented a significant component of the oral bacterial microbiomes of the dolphins and seals. However, sequences consistent with O. salmonicida were only found in the dolphin samples. Analyses of marine mammal microbiome studies in the NCBI databases showed sequences consistent with O. salmonicida from the common dolphin, striped dolphin, bottlenose dolphin Tursiops truncatus, humpback whale Megaptera novaeangliae, and harbour seal. Sequences from marine environmental studies in the NCBI databases showed no sequences consistent with O. salmonicida. The findings suggest that several species of marine mammals are natural hosts of O. salmonicida.

Modeling cetacean habitat use in an urban coastal area in southeastern Brazil

2020 ◽  
Vol 642 ◽  
pp. 227-240
Author(s):  
L Lodi ◽  
R Tardin ◽  
G Maricato
Keyword(s):  
Habitat Use ◽  
Protected Areas ◽  
Linear Models ◽  
Anthropogenic Activities ◽  
Buffer Zone ◽  
Humpback Whales ◽  
Southeastern Brazil ◽  
Major Influence ◽  
Cetacean Species ◽  
Few Data

Most studies of cetacean habitat use do not consider the influence of anthropogenic activities. We investigated the influence of environmental and anthropogenic variables on habitat use by humpback Megaptera novaeangliae and Bryde’s whales Balaenoptera brydei off the coast of the Brazilian city of Rio de Janeiro. Although there are 2 marine protected areas (MPAs) in this area, few data are available on cetacean habitat use or on the overlap of different cetacean species within these MPAs. Our aim was to evaluate the effectiveness of the MPAs and propose a buffer zone to better protect the biodiversity of the study area. We conducted systematic surveys and developed spatial eigenvector generalized linear models to characterize habitat use by the species in the study area. Habitat use by humpback whales was influenced only by depth, whereas for Bryde’s whales there was the additional influence of anthropogenic variables. For Bryde’s whales, which use the area for feeding, sea surface temperature and the distance to anchorages had a major influence on habitat use. We also showed that neither of the MPAs in the study area adequately protects the hotspots of either whale species. Most of the humpback whale grid cells with high sighting predictions were located within 2 km of the MPAs, while areas of high sighting prediction of Bryde’s whales were located up to 5 km from the MPAs, closer to beaches. Our findings provide important insights for the delimitation of protected areas and zoning of the MPAs.

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