scholarly journals Stranded dolphin stomach contents represent the free-ranging population's diet

2013 ◽  
Vol 9 (3) ◽  
pp. 20121036 ◽  
Author(s):  
Glenn Dunshea ◽  
Nélio B. Barros ◽  
Elizabeth J. Berens McCabe ◽  
Nicholas J. Gales ◽  
Mark A. Hindell ◽  
...  
Keyword(s):  
Bottlenose Dolphin ◽  
Prey Species ◽  
Prey Selection ◽  
Stomach Contents ◽  
Molecular Data ◽  
Habitat Associations ◽  
Fundamental Aspect ◽  
Dolphin Population ◽  
Free Ranging

Diet is a fundamental aspect of animal ecology. Cetacean prey species are generally identified by examining stomach contents of stranded individuals. Critical uncertainty in these studies is whether samples from stranded animals are representative of the diet of free-ranging animals. Over two summers, we collected faecal and gastric samples from healthy free-ranging individuals of an extensively studied bottlenose dolphin population. These samples were analysed by molecular prey detection and these data compared with stomach contents data derived from stranded dolphins from the same population collected over 22 years. There was a remarkable consistency in the prey species composition and relative amounts between the two datasets. The conclusions of past stomach contents studies regarding dolphin habitat associations, prey selection and proposed foraging mechanisms are supported by molecular data from live animals and the combined dataset. This is the first explicit test of the validity of stomach contents analysis for accurate population-scale diet determination of an inshore cetacean.

Intrapopulation variation in the diet of franciscana dolphin (Pontoporia blainvillei) off southern Brazil

2021 ◽  
pp. 1-17
Author(s):  
Manuela Bassoi ◽  
Eduardo R. Secchi ◽  
Daniel Danilewicz ◽  
Ignacio B. Moreno ◽  
Roberta A. Santos ◽  
...  
Keyword(s):  
Sexual Maturity ◽  
Linear Models ◽  
Prey Species ◽  
Prey Availability ◽  
Prey Selection ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Brazilian Coast ◽  
Pontoporia Blainvillei ◽  
Franciscana Dolphin

Abstract The franciscana dolphin (Pontoporia blainvillei) is a coastal dolphin endemic to the western South Atlantic Ocean. The dolphin is listed as vulnerable in the IUCN Red List, with incidental catches in gillnet fisheries the greatest conservation concern for this species. Insights into the feeding habits of this dolphin are essential to understand its distribution, movements and use of habitat, which are fundamental for effective management of the species. The feeding habits of franciscana dolphins were investigated from analyses of stomach contents of animals incidentally caught by two fishing operations from southern and northern regions of the southern Brazilian coast. In this study we investigate the existence of intrapopulation (sexual maturity and sex-related) variation in the diet of the franciscana dolphin, evaluating the spatial (northern and southern geographic areas) and seasonal influences. The analyses were based on Linear and Generalized Linear Models (LM and GLM). The majority of identified prey species were bottom-dwelling teleosts and the squid Doryteuthis sanpaulensis. The most important prey differed spatially and seasonally between northern and southern regions of the study area, and our results revealed significant differences between sexes and sexual maturity stages, mainly related to prey species sizes. This variation might indicate differences in prey selection, availability or habitat use patterns among these groups. In any case, these dietary differences are likely to minimize intraspecific competition for food resources, and/or indicate spatio-temporal variation in prey availability.

scholarly journals Bottlenose dolphins (Tursiops truncatus, Montagu 1821) in central-northern coast of Rio de Janeiro State, Brazil: stranding patterns and insights into feeding habits

10.5597/00228 ◽  
2017 ◽  
Vol 11 (1-2) ◽  
pp. 191-198 ◽  
Author(s):  
Jailson Moura ◽  
Davi Castro Tavares ◽  
Helio K.C. Secco ◽  
Salvatore Siciliano
Keyword(s):  
Body Length ◽  
Bottlenose Dolphin ◽  
Tursiops Truncatus ◽  
Rio De Janeiro ◽  
Prey Species ◽  
Bottlenose Dolphins ◽  
Stomach Contents ◽  
The Body ◽  
Northern Coast ◽  
Janeiro State

The bottlenose dolphin (Tursiops truncatus) may be one of the best known dolphin species worldwide, principally due to its coastal distribution in many regions. However, few studies about ecology, biology and threats have been conducted on the Brazilian coast. The aim of the present work is to analyze the stranding pattern and stomach contents of bottlenose dolphins in the central-north coast of the Rio de Janeiro State, from Saquarema to São Francisco de Itabapoana (~300km of coast line). Forty nine stranding events were recorded through regular beach surveys from 1999 to 2012 and also through access to previous published studies conducted since 1984. The strandings were distributed throughout the study area, but there was a trend of occurrence in the extreme southern and northern regions. Nine specimens showed evidence of accidental mortality in fishing nets. The strandings were more frequently recorded during autumn and winter (χ2; p < 0.05). Male bottlenose dolphins stranded more often than females, showing significant differences in this relationship (χ2; p < 0.05). Most stranded dolphins were classified as adults (> 230cm of body length) (χ2; p < 0.05). The body length varied from 106 to 335cm. Four prey species were found in the stomach contents from the three specimens of bottlenose dolphin analyzed. The most representative prey species was the cutlassfish (Trichiurus lepturus). This study showed that bottlenose dolphins are frequently found dead along the Rio de Janeiro State where they feed mainly on coastal fish. Future studies need to be conducted to improve the knowledge on this poorly known cetacean in Brazil.

PATTERNS OF GASTROPOD MOLLUSK PREDATION ON BIVALVE MOLLUSKS ALONG THE UPPER TEXAS GULF COAST

2018 ◽  
Vol 70 (1) ◽  
Author(s):  
Serena J. Randolph ◽  
Alan D. Maccarone
Keyword(s):  
Shell Thickness ◽  
Prey Species ◽  
Gulf Coast ◽  
Prey Selection ◽  
Drill Hole ◽  
The United States ◽  
Hole Diameter ◽  
Bivalve Mollusks ◽  
Collection Site ◽  
Drill Holes

Abstract Predation on bivalve mollusks by gastropod mollusks is common in coastal regions of the United States; however, few previous studies have examined whether drilling gastropods exhibit prey selection. In 2016, shells with small holes drilled by as many as two gastropod predators were collected at three sites separated by 30 km along the Texas Upper Gulf Coast on the Bolivar Peninsula (29° 40′N, 94° 90′W). The likeliest predators in these waters are the southern oyster drill (Stramonita haemastoma Linnaeus 1767) and the moon snail (Neverita duplicate Say 1822). Collected shells were identified to species and measurements were taken to examine statistical relationships between predators and prey species. These measurements included drill-hole diameter, shell thickness, drill-hole completeness, number of drill attempts, and collection site. Across the three locations, 17 different species of shells with drill holes were collected; of these, we focused on the ten most abundant species (n = 277 shells). The sample showed high variation in drill-hole diameter, shell thickness, and drill-hole completeness. Both the total number of holes and mean drill-hole diameter differed significantly among prey species (ANOVA, both P &lt; 0.0001). In addition, drill-hole diameter correlated directly with prey shell thickness (P &lt; 0.0001). Shells whose drill holes were complete were significantly thinner than shells with incomplete holes (P &lt; 0.0001). Mean prey shell thickness, mean drill-hole diameter, and mean number of drill holes all differed significantly by collection site (all P &lt; 0.0001). Ecological and morphological implications related to gastropod predation on mollusks are discussed.

Molecular determination of the origin of acephalic cysticercus

Parasitology ◽  
2004 ◽  
Vol 130 (2) ◽  
pp. 239-246 ◽  
Author(s):  
J.-Y. CHUNG ◽  
W.-G. KHO ◽  
S.-Y. HWANG ◽  
E.-Y. JE ◽  
Y.-T. CHUNG ◽  
...  
Keyword(s):  
Nadh Dehydrogenase ◽  
Fatal Outcome ◽  
Constitutive Expression ◽  
Molecular Data ◽  
Molecular Characteristics ◽  
Nadh Dehydrogenase Subunit ◽  
Subarachnoidal Space ◽  
Species Specific ◽  
Molecular Determination

Acephalic cysticercus (Ac), a rarely developed multilobulated and nonencysted form of larval Taenia, causes hydrocephalus or adhesive arachnoiditis in the ventricles and subarachnoidal space that often lead to fatal outcome in affected patients. Ac has been proposed to originate from T. solium on the basis of morphological features, while no molecular data supporting the presumption have been available. In the present study, we investigated the immunological properties as well as molecular characteristics of Ac that was obtained surgically from 6 patients. Immunoblotting of the cyst fluid from Ac samples demonstrated the constitutive expression of a T. solium metacestode (TsM) 10 kDa protein. Specific antibodies against the truncated 10 kDa protein, which appears to be species specific for TsM cysticercosis, were detected in both serum and cerebrospinal fluid samples of Ac patients. Nucleotide sequences of mitochondrial cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 1 (ND1) genes of Ac were almost identical to those of T. solium but differed substantially from those of the other Taenia species. In phylogenetic analysis, Ac clustered with T. solium in a well-supported clade. Our results strongly suggest that Ac may have originated from T. solium.

scholarly journals Prey consumed by Guiana dolphin Sotalia guianensis (Cetacea, Delphinidae) and franciscana dolphin Pontoporia blainvillei (Cetacea, Pontoporiidae) in an estuarine environment in southern Brazil

2012 ◽  
Vol 102 (2) ◽  
pp. 131-137 ◽  
Author(s):  
Marta J. Cremer ◽  
Pedro C. Pinheiro ◽  
Paulo C. Simões-Lopes
Keyword(s):  
Prey Species ◽  
Stomach Contents ◽  
Frequency Of Occurrence ◽  
Teleost Fishes ◽  
Southern Brazil ◽  
Sympatric Populations ◽  
Sotalia Guianensis ◽  
Important Prey ◽  
Pontoporia Blainvillei ◽  
Lolliguncula Brevis

The present study provides information about the diet of sympatric populations of small cetaceans in the Babitonga Bay estuary. This is the first study on the diet of these species in direct sympatry. The stomach contents of seven Guiana dolphins Sotalia guianensis and eight franciscanas Pontoporia blainvillei were analyzed. The prey of both cetaceans was mostly teleost fishes, followed by cephalopods. We identified 13 teleost fishes as part of the diet of the franciscanas, and 20 as part of the diet of Guiana dolphins. Lolliguncula brevis was the only cephalopod recorded, and was the most important prey for both cetaceans. Stellifer rastrifer and Gobionellus oceanicus were also important for franciscana, so as Mugil curema and Micropogonias furnieri were important for Guiana dolphins. Stellifer rastrifer and Cetengraulis edentulus were the fishes with the highest frequency of occurrence for franciscana (50%), while Achirus lineatus, C. edentulus, S. brasiliensis, Cynoscion leiarchus, M. furnieri, M. curema, Diapterus rhombeus, Eugerres brasilianus and G. oceanicus showed 28.6% of frequency of occurrence for Guiana dolphins. Franciscanas captured greater cephalopods than the Guiana dolphins in both total length (z= -3.38; n= 40; p< 0.05) and biomass (z = -2.46; n = 40; p<0.05). All of the prey species identified occur inside the estuary, which represents a safe habitat against predators and food availability, reinforcing the importance of the Babitonga Bay for these cetacean populations.

scholarly journals The Flying Saucer: Tomography of the thermal and density gas structure of an edge-on protoplanetary disk

2017 ◽  
Vol 607 ◽  
pp. A130 ◽  
Author(s):  
A. Dutrey ◽  
S. Guilloteau ◽  
V. Piétu ◽  
E. Chapillon ◽  
V. Wakelam ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Direct Determination ◽  
Molecular Data ◽  
Temperature Structure ◽  
Gas Temperature ◽  
Star Forming ◽  
Star Forming Regions ◽  
Flying Saucer ◽  
Grain Properties

Context. Determining the gas density and temperature structures of protoplanetary disks is a fundamental task in order to constrain planet formation theories. This is a challenging procedure and most determinations are based on model-dependent assumptions. Aims. We attempt a direct determination of the radial and vertical temperature structure of the Flying Saucer disk, thanks to its favorable inclination of 90 degrees. Methods. We present a method based on the tomographic study of an edge-on disk. Using ALMA, we observe at 0.5″ resolution the Flying Saucer in CO J = 2–1 and CS J = 5–4. This edge-on disk appears in silhouette against the CO J = 2–1 emission from background molecular clouds in ρ Oph. The combination of velocity gradients due to the Keplerian rotation of the disk and intensity variations in the CO background as a function of velocity provide a direct measure of the gas temperature as a function of radius and height above the disk mid-plane. Results. The overall thermal structure is consistent with model predictions, with a cold (<12−15 K) CO-depleted mid-plane and a warmer disk atmosphere. However, we find evidence for CO gas along the mid-plane beyond a radius of about 200 au, coincident with a change of grain properties. Such behavior is expected in the case of efficient rise of UV penetration re-heating the disk and thus allowing CO thermal desorption or favoring direct CO photo-desorption. CO is also detected at up to 3–4 scale heights, while CS is confined to around 1 scale height above the mid-plane. The limits of the method due to finite spatial and spectral resolutions are also discussed. Conclusions. This method appears to be a very promising way to determine the gas structure of planet-forming disks, provided that the molecular data have an angular resolution which is high enough, on the order of 0.3−0.1″ at the distance of the nearest star-forming regions.

Ingesta particle size, food handling and ingestion in the tammar wallaby (Macropus eugenii Desmarest)

1999 ◽  
Vol 47 (1) ◽  
pp. 75 ◽  
Author(s):  
R. G. Lentle ◽  
K. J. Stafford ◽  
M. A. Potter ◽  
B. P. Springett ◽  
S. Haslett
Keyword(s):  
Particle Size ◽  
New Zealand ◽  
Particle Size Distribution ◽  
Stomach Contents ◽  
Tammar Wallaby ◽  
Food Handling ◽  
Macropus Eugenii ◽  
Food Particles ◽  
Chewing Rates ◽  
Free Ranging

The particle size distribution of stomach contents from 25 tammar wallabies (Macropus eugenii Desmarest) shot in the Okataina State Forest and adjoining farmland near Rotorua, New Zealand, were determined. There was a greater percentage of finer, and a smaller percentage of larger, particles than reported in the stomach contents of larger macropods. The chewing and biting activities of four free-ranging tammars fitted with radio-microphone collars were monitored. Chewing rates (chews per minute) were similar to those of other small herbivorous vertebrates. There were significantly lower rates of chewing and higher chew-to- bite ratios when browsing than when grazing. Observations of browsing by three captive tammars showed inefficient handling by mutually opposed palms and digitopalmar grip, resulting in low rates of ingestion. We suggest that tammars lower the time necessary for fermentation of food by reducing the size of food particles, and that their choice between graze and browse is influenced by food handling and chewing investment.

scholarly journals On the behaviour of an under-studied population of bottlenose dolphins in the Southern Adriatic Sea

2018 ◽  
Vol 99 (4) ◽  
pp. 1017-1023 ◽  
Author(s):  
Flavio Affinito ◽  
Cristobal Olaya Meza ◽  
Aylin Akkaya Bas ◽  
Deborah Brill ◽  
Guy Whittaker ◽  
...  
Keyword(s):  
Group Size ◽  
Bottlenose Dolphin ◽  
Adriatic Sea ◽  
Bottlenose Dolphins ◽  
Anthropogenic Pressure ◽  
Social Predictors ◽  
Dolphin Population ◽  
Autumn And Winter ◽  
Effective Conservation ◽  
Study Monitoring

AbstractPerhaps the world's best-known cetacean, the bottlenose dolphin shows considerable variation in behaviour between and within populations in relation to differences in natural and anthropogenic conditions. Drivers of behavioural variation need to be identified to understand the dynamics of wild dolphin populations. Little research has been published on the bottlenose dolphin population found in the Southern Adriatic Sea. Using a set of spatial, temporal and social predictors, we aimed to investigate what variables are related to the behaviour of an under-studied population of bottlenose dolphins along the coastline of Montenegro. We present the results of a year-long study monitoring the behaviour of bottlenose dolphins along coastal Montenegro. We considered the effect of topography, seasonality and group size. A large proportion of travelling (55%) small groups (mean 4, range 1–9) in shallow waters (<50 m) was observed. We showed that seasonality alone explained behaviour best, with surface-feeding and socializing-resting increasing in autumn and winter. Group size was found to be a result of behavioural choice. We suggest seasonal changes in environmental conditions and anthropogenic pressure may explain the recorded behavioural pattern. This research points to the necessity of increased collaboration in the region to help understand complex patterns in behaviour and habitat use of local dolphin populations if effective conservation measures are to be developed.

Sign in / Sign up

Export Citation Format

Share Document