scholarly journals Opportunistic gut sampling indicates differential diet and plastic ingestion risk in Indian dugongs

2021 ◽  
Author(s):  
Sumit Prajapati ◽  
Chinmaya Ghanekar ◽  
Sameeha Pathan ◽  
Rukmini Shekar ◽  
K. Madhu Magesh ◽  
...  
Keyword(s):  
Marine Mammals ◽  
Tamil Nadu ◽  
Stomach Contents ◽  
Gut Contents ◽  
Dietary Composition ◽  
Seagrass Species ◽  
Fine Spatial Scale ◽  
Direct Observations ◽  
Feeding Biology ◽  
Indian Waters

Dugongs, exclusively seagrass foragers, are globally threatened marine mammals. Knowledge on their feeding biology has been derived from few direct observations and mostly by analysis of stomach contents. Given limitations in data from Indian populations, dugong strandings serve as an opportunity to understand their dietary composition through gut sampling. In this paper, we utilize the gut contents collected from stranded dugongs to detect differences in the seagrass foraging between two isolated pockets of dugong distribution (Tamil Nadu and Gujarat) and supplement existing knowledge on dugong feeding biology in Indian waters. We extracted, enumerated and identified seagrass species from dugong gut contents. The proportion of seagrass leaf fragments were found higher (>40%) than other fragments in all the gut samples analysed. We recorded two seagrass genera (Halophila spp. and Halodule spp.) from Gujarat and five seagrass genera (Halophila spp., Halodule spp., Cymodocea spp., Enhalus spp., Syringodium spp.) from Tamil Nadu dugong individuals. We also obtained anthropogenic debris such as plastic, fishing net and wood fragments from the gut samples. We suggest enhanced monitoring of seagrass habitats and fine spatial scale threat mapping in entire dugong distribution range in India.

scholarly journals The impacts of climate change on marine mammals: early signs of significant problems

Oryx ◽  
2007 ◽  
Vol 41 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Mark P. Simmonds ◽  
Stephen J. Isaac
Keyword(s):  
Climate Change ◽  
Marine Mammal ◽  
Marine Mammals ◽  
Delphinapterus Leucas ◽  
Polar Regions ◽  
Baleen Whale ◽  
Direct Observations ◽  
Management Plans ◽  
Conservation Plans ◽  
Impacts Of Climate Change

Climate change is now known to be affecting the oceans. It is widely anticipated that impacts on marine mammals will be mediated primarily via changes in prey distribution and abundance and that the more mobile (or otherwise adaptable) species may be able to respond to this to some extent. However, the extent of this adaptability is largely unknown. Meanwhile, within the last few years direct observations have been made of several marine mammal populations that illustrate reactions to climate change. These observations indicate that certain species and populations may be especially vulnerable, including those with a limited habitat range, such as the vaquita Phocoena sinus, or those for which sea ice provides an important part of their habitat, such as narwhals Monodon monoceros, bowhead Balaena mysticetus and beluga Delphinapterus leucas whales and polar bears Ursus maritimus. Similarly, there are concerns about those species that migrate to feeding grounds in polar regions because of rapidly changing conditions there, and this includes many baleen whale populations. This review highlights the need to take projected impacts into account in future conservation and management plans, including species assessments. How this should be done in an adequately precautionary manner offers a significant challenge to those involved in such processes, although it is possible to identify at this time at least some species and populations that may be regarded as especially vulnerable. Marine ecosystems modellers and marine mammal experts will need to work together to make such assessments and conservation plans as robust as possible.

Termitivore or detritivore? A quantitative investigation into the diet of the East African caecilian Boulengerula taitanus (Amphibia: Gymnophiona: Caeciliidae)

2004 ◽  
Vol 54 (1) ◽  
pp. 45-56 ◽  
Author(s):  
G. John Measey ◽  
Olivier Gaborieau
Keyword(s):  
Organic Matter ◽  
Stomach Contents ◽  
Gut Contents ◽  
Generalist Predators ◽  
East African ◽  
Quantitative Investigation ◽  
Soil Macrofauna ◽  
Taita Hills ◽  
Specialist Predators ◽  
African Genus

AbstractMost caecilians are thought to be generalist predators of soil ecosystem engineers (earthworms, termites and ants), but it has been suggested that members of the East African genus Boulengerula are specialist predators. Surprisingly, in the only detailed study of diet of any Boulengerula, the authors speculated that B. taitanus is partly detritivorous, based on the large amount of organic matter found in the alimentary canal. Here we test the conflicting hypotheses that B.taitanus is a termitivore or detritivore, using the stomach and gut contents of 47 specimens collected in the Taita Hills, Kenya. Termites and earthworms contribute most significantly to diet by number and mass, respectively. These constitute the major dietary items, together with dipteran larvae and other soil macrofauna. Contents of the intestine are mostly soil and organic matter originating from prey items. The mass content of the intestines averages 69% of total gut contents, and is significantly greater than identifiable stomach contents. The null hypotheses that B. taitanus is a generalist and a predator are not rejected.

Strategies for coexistence in three species of net-spinning caddisflies (Trichoptera) in second-order southern Appalachian streams

1977 ◽  
Vol 55 (11) ◽  
pp. 1829-1840 ◽  
Author(s):  
Diane Malas ◽  
J. Bruce Wallace
Keyword(s):  
Particle Size ◽  
Vascular Plant ◽  
Distribution Patterns ◽  
Gut Contents ◽  
Dietary Composition ◽  
Particle Sizes ◽  
Southern Appalachian ◽  
Fine Particulate ◽  
Animal Material ◽  
Appalachian Streams

Three species of net-spinning caddisflies, Parapsyche cardis, Diplectrona modesta, and Dolophilodes distinctus were studied. Larvae of Dolophilodes are found at the lowest current velocities followed by Diplectrona, then Parapsyche, which prefer the higher velocities. Parapsyche larvae are most abundant on upper surfaces of stones while Diplectrona and Dolophilodes are found primarily on undersides of stones. These distribution patterns are probably related to capture net mesh dimensions which differ greatly for the three species, Parapsyche having the largest and Dolophilodes the smallest meshes. Significant correlations existed for mean foregut particle size and capture net mesh opening size between instars of all species within seasons, between instars of all species throughout the year, and between instars within species throughout the year. These correlations support the contention that particle size selection is an important aspect of feeding differences between species. There are large differences between mesh opening sizes of last-instar Dolophilodes and first- and second-instar Diplectrona larvae. However, based on mean particle size measurements of foregut contents, there is no corresponding gap in the spectrum of particle sizes used for food. Dietary composition also varied between species. Parapsyche consumed primarily animal material. Fine particulate detritus composed over 95% of Dolophilodes gut contents and Diplectrona consumed mostly vascular plant and detritus fragments in late instars and fine particulate detritus in early instars.

scholarly journals Food and Feeding of the Blue Swimmer Crab, Portunus Pelagicus (Linnaeus, 1758) (Decapoda, Brachyura) along the Coast of Mandapam, Tamil Nadu, India

Crustaceana ◽  
2011 ◽  
Vol 84 (10) ◽  
pp. 1169-1180 ◽  
Keyword(s):  
Tamil Nadu ◽  
Carapace Width ◽  
Stomach Contents ◽  
Full Stomach ◽  
Portunus Pelagicus ◽  
Food Items ◽  
Significant Difference ◽  
Size Groups ◽  
Food And Feeding ◽  
Trawl Catches

AbstractFood habits of the blue swimmer crab, Portunus pelagicus were investigated using specimens collected from trawl catches in the Mandapam region, Tamil Nadu, along the east coast of India (9°20-25′N 79°5-10′E), during the period January to December, 1999. The stomach contents of 452 crabs, ranging from 61 to 180 mm carapace width, were analysed. Their diet included crustaceans, molluscs, fishes, unidentifiable matter, and debris. In adult crabs, crustaceans constituted the dominant food source and these were present in 78.43% of the stomachs analysed. The stomach contents of juveniles and sub-adults were dominated by debris. There was no significant difference between sexes in the frequency of occurrence of food items or in their “percentage points” [= the (virtual) percentual contribution to the fullness of a 100% full stomach]. However, there was a difference between the stomachs of ovigerous and non-ovigerous females. There were also significant differences in the preference for food items in the different size groups of the crab. The results collected from the present study showed that P. pelagicus exhibits, in this region at least, a clear preference for crustaceans.

Aspects of the feeding biology of the pectinacean Bathypecten vulcani, a peri-hydrothermal vent bivalve

2003 ◽  
Vol 83 (3) ◽  
pp. 479-482 ◽  
Author(s):  
Gaël LE PENNEC ◽  
Peter G. BENINGER ◽  
Marcel LE PENNEC ◽  
Anne DONVAL
Keyword(s):  
Digestive Tract ◽  
Hydrothermal Vent ◽  
Stomach Contents ◽  
Frontal Surface ◽  
Mineral Particles ◽  
East Pacific ◽  
Feeding Biology ◽  
Crystalline Style ◽  
Bathymodiolus Thermophilus ◽  
Cytological Characteristics

The feeding biology of Bathypecten vulcani, a peri-hydrothermal vent pectinacean, was investigated using histological and scanning electron microscope studies of the gills and stomach contents of specimens sampled from the 9° and 13°N sites of the East Pacific Rise. Salient characteristics were compared with those of Bathymodiolus thermophilus from the same and similar habitats. The gills of Bathypecten vulcani displayed heterogeneous organic and mineral particles on their frontal surface. The digestive tract possessed well-developed structures (whose anatomical and cytological characteristics indicated full functionality), typically found in bivalves from littoral aerobic environments, as well as in Bathymodiolus thermophilus, which is capable of suspension-feeding: oesophagus, stomach, crystalline style, digestive gland, and intestine. Observations of stomach contents revealed diverse particles from the photic zone, including debris from diatoms and coccolithophorans. In contrast to Bathymodiolus thermophilus, bacteria were rarely observed in the digestive tract, indicating a more complete reliance on surface-originating particles.

The Ecology of the Eastern Water Rat Hydromys Chrysogaster at Griffith, N.s.w.: Food and Feeding Habits.

1978 ◽  
Vol 5 (1) ◽  
pp. 59 ◽  
Author(s):  
P Woollard ◽  
WJM Vestjens ◽  
L Maclean
Keyword(s):  
Plant Material ◽  
Feeding Habits ◽  
Starch Content ◽  
South Australia ◽  
Stomach Contents ◽  
Freshwater Mussel ◽  
Time Of Day ◽  
Gut Contents ◽  
South Wales ◽  
Hydromys Chrysogaster

The eastern water rat, Hydromys chrysogaster, lives in inland waters, estuaries, sea beaches and islands from Queensland to South Australia and Tasmania. It is adapted to semiaquatic life and changes in its molar teeth may be an adaptation to diet of crustaceans and molluscs. The present study was of 408 stomach contents and 316 contents of caecum with rectum, collected in New South Wales in 1970-73 from permanent Typha swamp. From elsewhere there were 12 other stomach and 11 gut contents and live rats were observed. At any time of day but particularly in evenings the rats swam along the bank or between logs or reed clumps, foraging and catching fish. Captive rats crushed small mussels and left large mussels to open by exposure. Diet varied with season and included crustaceans, mostly the yabbie, a crayfish (Cherax destructor), spiders, all Araneida with one identified as of the suborder Pisauridae, a fishing spider. Insects were the main food and were eaten in all seasons, and included larvae, nymphs and adults. Only 1% of rats had the freshwater mussel Veksurio ambiguus but the flesh was difficult to identify and empty shells were often found. Fish were eaten all the year, and were found in up to 35% of rats in autumn and winter; fish may be underestimated because flesh is not easily recognised and hard parts are not much eaten. Several species of fish, mostly introduced, were identified, their ages estimated from their scales, and length was calculated to be up to 36 cm. Frogs and macquaria tortoise (Emydura macquarii) were eaten. Birds were eaten all the year and were in up to 10% of stomachs in winter. Personal communications are quoted, from persons having seen H. chrysogaster capture large adult birds including duck and mutton bird (Puffinus tenuirostris). Captive rats were able to open cracked hen's eggs but left intact eggs. Plant material was eaten as food and possibly also in stomachs of prey. For 3 rats half the starch content was plant; 3 other stomachs had 5, 40 and 50% plant material, Azolla fuliculoides. Differences in diet with age are described. H. chrysogaster was an adaptable and opportunist feeder, making use of transient plenty of insects, exploiting plagues among other species and using plants during shortage of food. They may control introduced pests such as perch, or control yabbies in irrigation ditches.

scholarly journals Variability in the diet diversity of catfish highlighted through DNA barcoding

2020 ◽  
Author(s):  
Chinnamani Prasannakumar ◽  
Gunasekaran Iyyapparajanarasimapallavan ◽  
M. Ashiq Ur Rahman ◽  
P. Mohanchander ◽  
T. Sudhakar ◽  
...  
Keyword(s):  
Dna Barcoding ◽  
Monsoon Season ◽  
Stomach Contents ◽  
Hermit Crabs ◽  
Gut Contents ◽  
Reference Database ◽  
Perna Viridis ◽  
Fish Diet ◽  
Diet Diversity ◽  
Post Monsoon

AbstractIdentification and quantification of fish diet diversity was the first step in understanding the food web dynamics and ecosystem energetics, where the contribution of DNA barcoding technique has been important. We used DNA barcoding to identify the stomach contents of a euryhaline, benthophagous catfish Ariius maculatus. From 40 catfish stomach items sampled in two different seasons, we barcoded 67 piscine and macro-invertebrates prey items, identified as belonging to 13 species in 4 major phyla (viz., Chordate, Arthropod, Annelida and Mollusca). It is important to note that the mollusc taxa (Meritrix meritrix and Perna viridis) and a species of fish (Stolephorus indicus) could not be found among the gut contents of A. maculatus sampled during the pre- and post-monsoon season, respectively. Among the piscine diets of A. maculatus, Eubleekeria splendens (23.5%) and Stolephorus indicus (23.5%) were the major prey taxa during pre-monsoon season. The hermit crabs forms the major constituents of both pre- and post-monsoon seasons, among invertebrate taxa. Polychaete, Capitella capitata (25.92%) was abundantly consumed invertebrates next to hermit crabs. We noticed that in pre-monsoon A. maculatus was more piscivorous than post-monsoon. As revealed through Kimura-2 parametric pair­wise distance analysis, the diet diversity was relatively higher in post-monsoon. The accumulation curve estimated 57 haplotypes within 14 barcoded species (including the host A. maculatus). Majority of haplotypes were found among fishes (47.36%) followed by Arthropods (28.07%), Annelids (14.03%) and Mollusca (10.52%), respectively. This study also highlights that there is a growing concern about A. maculatus’s aggressive predation on commercially important stocks of fish and invertebrates. We will continue to expand the coverage of species barcoded in the reference database, which will become more significant as meta- and environmental DNA barcoding techniques become cheaper and prevalent.

scholarly journals Morphological dietary composition of Antarctic toothfish (Dissostichus mawsoni) along the East Antarctic continental slope

2021 ◽  
Author(s):  
Gi Chang Seong ◽  
Seok-Gwan Choi ◽  
Sangdeok Chung ◽  
Doo Hae An ◽  
Hyun-Woo Kim ◽  
...  
Keyword(s):  
Continental Slope ◽  
Morphological Analysis ◽  
Stomach Contents ◽  
Dietary Composition ◽  
Ecosystem Structure ◽  
Antarctic Toothfish ◽  
Dissostichus Mawsoni ◽  
Index Of Relative Importance ◽  
And Function ◽  
Ecosystem Structure And Function

Abstract To predict how the fishing of Antarctic toothfish, Dissostichus mawsoni , would affect the ecosystem, it is necessary to understand the species’ ecological niche. Morphological analysis of the stomach contents of 960 D . mawsoni specimens collected at depths of 946–1,600 m along the East Antarctic continental slope from December 2016 to March 2017 was used to assess dietary composition according to depth, sex, site, and size. Fishes were the most common prey item for D . mawsoni , comprising 97.8% based on the index of relative importance. Among the nine fish families consumed by D . mawsoni , Macrouridae was the dominant taxon. The size of D . mawsoni increased with depth. The dietary composition of D . mawsoni did not show significant differences by depth or sex, but did differ with site and size. D . mawsoni was the top predator in the ecosystem along the East Antarctic continental slope and can be considered an opportunistic feeder, feeding on abundant food in the environment. Therefore, additional studies of the diet of Antarctic toothfish are necessary to maintain the ecosystem structure and function in a changing environment, and the results of this study can be used as a monitoring baseline.

Studies on the Marsupial Glider, Schoinobates Volans (Kerr). 4. Feeding Biology.

1973 ◽  
Vol 21 (2) ◽  
pp. 213 ◽  
Author(s):  
TG Marples
Keyword(s):  
Food Intake ◽  
Tree Species ◽  
Feeding Rate ◽  
Stomach Contents ◽  
Dry Weight ◽  
Daily Food Intake ◽  
Feeding Biology ◽  
Daily Food ◽  
Total Dry Weight

Stomach contents of 133 gliders were examined for total dry weight of food, and calorific values. From four years' collections it was estimated that daily food intake was 20g dry wt. or 108 kcal. The feeding rate was estimated at 2.8g dry wt. hr-1 and was observed to be leaves, buds, and bark of the major tree species. The estimated harvest by the glider population was 6 kg dry wt. ha-1 yr-I (3.2 x 10*4 kcal ha-1 yr-I).

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