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 Applying and refining DNA analysis to determine the identity of plant material extracted from the digestive tracts of katydids

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6808 ◽  
Author(s):  
Laurel B. Symes ◽  
Nicole L. Wershoven ◽  
Lars-Olaf Hoeger ◽  
Jessica S. Ralston ◽  
Sharon J. Martinson ◽  
...  
Keyword(s):  
Plant Material ◽  
Dna Analysis ◽  
Feeding Habits ◽  
Time Of Day ◽  
Barro Colorado Island ◽  
Gut Contents ◽  
Neotropical Forest ◽  
Amplification Success ◽  
Significant Difference ◽  
Primer Sets

Background Feeding habits are central to animal ecology, but it is often difficult to characterize the diet of organisms that are arboreal, nocturnal, rare, or highly mobile. Genetic analysis of gut contents is a promising approach for expanding our understanding of animal feeding habits. Here, we adapt a laboratory protocol for extracting and sequencing plant material from gut contents and apply it to Neotropical forest katydids (Orthoptera: Tettigoniidae) on Barro Colorado Island (BCI) in Panama. Methods Our approach uses three chloroplast primer sets that were previously developed to identify vegetation on BCI. We describe the utility and success rate of each primer set. We then test whether there is a significant difference in the amplification and sequencing success of gut contents based on the size or sex of the katydid, the time of day that it was caught, and the color of the extracted gut contents. Results We find that there is a significant difference in sequencing success as a function of gut color. When extracts were yellow, green, or colorless the likelihood of successfully amplifying DNA ranged from ~30–60%. When gut extracts were red, orange, or brown, amplification success was exceptionally low (0–8%). Amplification success was also higher for smaller katydids and tended to be more successful in katydids that were captured earlier in the night. Strength of the amplified product was indicative of the likelihood of sequencing success, with strong bands having a high likelihood of success. By anticipating which samples are most likely to succeed, we provide information useful for estimating the number of katydids that need to be collected and minimizing the costs of purifying, amplifying, and sequencing samples that are unlikely to succeed. This approach makes it possible to understand the herbivory patterns of these trophically important katydids and can be applied more broadly to understand the diet of other tropical herbivores.

scholarly journals Cladocerans from gut contents of fishes associated to macrophytes from Taquari River Basin, MS, Brazil

2012 ◽  
Vol 24 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Adriana Maria Güntzel ◽  
Ilze Katsue Morita Melo ◽  
Kennedy Francis Roche ◽  
Valéria Flávia Batista da Silva ◽  
Priscila Gusmão Pompiani
Keyword(s):  
River Basin ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Oxbow Lake ◽  
Gut Contents ◽  
Small Fish ◽  
Short Discussion ◽  
Wet Season ◽  
Fish Feeding ◽  
Important Food Source

AIM: The aim of this study was to identify the cladocerans species from the gut contents of fishes sampled in an oxbow lake from Taquari River Basin, MS, with the specific view of investigating the importance of these crustaceans in the fishes diets; METHODS: Sampling was carried out in April and August of 2005 (dry season) and January of 2006 (wet season). The fish were captured with a sieve. In the laboratory, individuals were identified and stomachs were removed and weighed. The stomach contents were identified, and a Feeding Index calculated; RESULTS: The items most consumed by fishes were filamentous algae, Cladocera and detritus. The Cladocera were especially important in the August and January samples, and consisted primarily of Chydoridae; cladocerans were most consumed by species of Serrapinnus and by Mesonauta festivus. Fish fed more in April, with decreases occurring in stomach fullness on the other two sampling dates. CONCLUSIONS: Cladocerans associated with macrophytes may be an important food source for small fish individuals in marginal lakes from Taquari River Basin. The relative importance of the Chydoridae in the guts may have been due to the high relative abundance and species richness of this group in the environment. A short discussion on fish feeding habits was included in the text.

scholarly journals Feeding Habits of Different Fish Species in Negombo Lagoon

2019 ◽  
Vol 8 (2) ◽  
pp. 86-96
Author(s):  
Neetha Punchihewa ◽  
M.P.C. Silva
Keyword(s):  
Fish Species ◽  
Niche Breadth ◽  
Feeding Habits ◽  
Juvenile Fish ◽  
Stomach Contents ◽  
Gut Contents ◽  
Filamentous Algae ◽  
Relative Importance ◽  
Food Items ◽  
Plant Matter

To investigate the feeding habits of different fish species in Negombo lagoon, fish species were collected from Kadolkele and Liyanagemulla sites during February 2015 to July 2015 using a drag net. Collected specimens were preserved in 5% formalin. Later, the fish specimens were dissected, and stomach contents were mixed with water to make a suspension. One ml of suspension was added to the Sedgewick Rafter cell, and examined under the light microscope. The occurrence %, volume %, numbers %, and the Relative Importance Values (RIV) were calculated. The gut contents of 62 samples from 12 fish species were analyzed; 11 species were found to feed on mangroves, 10 on seagrasses, and 8 on filamentous algae. 13 food items were identified. Most of the analysed fish were categorized as omnivores and opportunistic feeders. The juvenile fish mainly feed on a combination of mangroves, seagrasses and filamentous algae. Apart from plant matter, the juvenile fish were found to feed upon Cyclops sp. and mysids. Although Hemirhamphus marginatus is an omnivore, it specially fed on mangroves, seagrasses and filamentous algae. Furthermore, H. marginatus consumed common food items in both habitats except mangroves and molluscs, and the shifting of its diet was depended on the availability of food. The broadest niche breadth was recorded by H. marginatus and the shortest niche breadth by the herbivorous fish species, Siganus vermiculatus and Liza macrolepis. Caranx sexfasciatus exhibited an ontogenetic shift in their diet. The smaller C. sexfasciatus was a carnivore and the larger individuals of the same species were herbivores.

scholarly journals Diet of the lizard Mabuya agilis (Sauria; Scincidae) in an insular habitat (Ilha Grande, RJ, Brazil)

2004 ◽  
Vol 64 (1) ◽  
pp. 135-139 ◽  
Author(s):  
C. F. D. Rocha ◽  
D. Vrcibradic ◽  
M. Van Sluys
Keyword(s):  
Plant Material ◽  
Feeding Habits ◽  
Stomach Contents

We examined the stomach contents of 21 specimens of Mabuya agilis (Sauria; Scincidae) collected during February 2001 at the restinga habitat of Praia do Sul, in Ilha Grande, RJ, Brazil. Diet was composed of various types of small arthropods, with no plant material being eaten. Spiders were the most important items in the diet, followed by orthopterans. Apart from the absence of isopterans, the diet of Mabuya agilis from this insular area was similar to those of other conspecific mainland populations. This suggests that factors such as insularity and the absence of other small sympatric lizards may not have a significant effect on the feeding habits of the Praia do Sul population.

In A Fix: Fixed-Term Parliaments in the Australian States

2013 ◽  
Vol 41 (2) ◽  
pp. 265-298
Author(s):  
Peter Congdon
Keyword(s):  
Western Australia ◽  
Prime Minister ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
Constitutional Amendments ◽  
South Wales

Constitutional systems of Westminster heritage are increasingly moving towards fixed-term parliaments to, amongst other things, prevent the Premier or Prime Minister opportunistically calling a ‘snap election’. Amongst the Australian states, qualified fixed-term parliaments currently exist in New South Wales, South Australia and Victoria. Queensland, Tasmania and Western Australia have also deliberated over whether to establish similar fixed-term parliaments. However, manner and form provisions in those states' constitutions entrench the Parliament's duration, Governor's Office and dissolution power. In Western Australia and Queensland, unlike Tasmania, such provisions are doubly entrenched. This article considers whether these entrenching provisions present legal obstacles to constitutional amendments establishing fixed-term parliaments in those two states. This involves examining whether laws fixing parliamentary terms fall within section 6 of the Australia Acts 1986 (Cth) & (UK). The article concludes by examining recent amendments to the Electoral Act 1907 (WA) designed to enable fixed election dates in Western Australia without requiring a successful referendum.

Feeding ecology of Symbolophorus californiensis larvae (Teleostei: Myctophidae) in the southern transition region of the western North Pacific

2009 ◽  
Vol 90 (6) ◽  
pp. 1249-1256 ◽  
Author(s):  
Chiyuki Sassa
Keyword(s):  
Transition Region ◽  
North Pacific ◽  
Western North Pacific ◽  
Developmental Stages ◽  
Feeding Habits ◽  
Larval Growth ◽  
Trophic Niche ◽  
Size Class ◽  
Gut Contents ◽  
Wide Range

The feeding habits of myctophid larvae of Symbolophorus californiensis were examined in the southern transition region of the western North Pacific where the main spawning and nursery grounds of S. californiensis are formed. This species is a key component of the pelagic ecosystems of this region, and their larvae attain one of the largest sizes among myctophids. To analyse gut contents larvae, including most life history stages after yolk-sac absorption (3.7 to 22.2 mm body length (BL)), were collected in the upper 100 m layer in 1997 and 1998. Feeding incidence was higher during the day than at night (53.1–92.3% versus 0–5.6%), and daytime feeding incidence increased gradually with larval growth. Larvae fed mainly on copepods of various developmental stages. Larvae of S. californiensis showed an ontogenetic change in their diet: larvae ≤7.9 mm BL (i.e. preflexion stage) fed mainly on copepod eggs and nauplii, while the larvae ≥8 mm BL consumed mainly calanoid copepodites such as Pseudocalanus and Paracalanus spp. In the largest size-class (16–22.2 mm BL), the furcilia stage of euphausiids was also an important prey item. There was an increase in the average prey size with growth in larvae ≤11.9 mm BL, while the number of prey eaten positively correlated with growth in larvae ≥12 mm BL. The trophic niche breadth also increased with larval growth, which would ensure a wide range of available food resources for the larger size-class larvae.

Elemental composition of mantle tissue granules in Hyridella depressa (Unionida) from the Hawkesbury-Nepean River system, Australia: inferences from catchment chemistry

2000 ◽  
Vol 51 (2) ◽  
pp. 183 ◽  
Author(s):  
Maria Byrne ◽  
Peter A. Vesk
Keyword(s):  
Freshwater Mussel ◽  
River System ◽  
Direct Analysis ◽  
Common Elements ◽  
Mantle Tissue ◽  
South Wales ◽  
The Common ◽  
Australian Freshwater ◽  
River Site

The Australian freshwater mussel Hyridella depressa sequesters elements in calcium phosphate (CaP) granules that form extensive aggregations in its tissues. Elements contained in these granules were determined by X-ray microanalysis of river and lake mussels from the Hawkesbury–Nepean River system, New South Wales. Granules in freeze-substituted mantle tissue were analysed to determine the variation in element profiles in granules among mussels and among sites. For the common elements Ca, P, Fe, Mg and Mn, granule composition reflected catchment lithology and site trophic status and indicated exogenous input. These were most important for differentiation among lake sites and also indicated differences between lake and river mussels. Site differences seen with some common elements in granules from lake mussels correlated with differences in water chemistry. Trace elements, particularly Al, Cu, Zn and Pb, were also important in lake and river site differentiation. The granules play a major role in element dynamics in freshwater mussel tissues and provide a focal structure for direct analysis of element accumulation by these bivalves. The results indicate that characterization of element content of granules in mussel populations would provide valuable insights into animal–element interactions in freshwater systems for ecological and ecotoxicological investigations.

The Relation Between the Food of the Australian Barracouta, Thyrsites atun (Euphrasen), and Recent Fluctuations in the Fisheries

1957 ◽  
Vol 8 (1) ◽  
pp. 29 ◽  
Author(s):  
M Blackburn
Keyword(s):  
Population Distribution ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
Downward Trend ◽  
Small Fish ◽  
Fish Diet ◽  
Upward Trend ◽  
Independent Evidence ◽  
South Wales

The diet of surface-swimming Australian barracouta was studied from over 10,000 stomachs. The principal prey organisms in Bass Strait are the euphausiid Nyctiphanes australis Sars, the anchovy Engraulis australis (White), and young barracouta, in that order; and in eastern Tasmania Nyctiphanes, Engraulis, and the sprat Clupea bassensis McCulloch, in that order. The pilchard Sardinops neopilchardus (Steindachner) is not an important item of the diet in these regions although it is so in New South Wales, South Australia, and Western Australia. The jack mackerel Trachurus declivis Jenyns is a significant item in eastern Tasmania and New South Wales but not in Bass Strait. These and other features of the fish diet of the barracouta reflect actual availability of the various small fish species in the waters. Barracouta eat Nyctiphanes by herding them into dense masses (or finding them already concentrated) and swallowing them. The movements of the anchovy make it unavailable to Bass Strait and eastern Tasmanian barracouta for much of the summer and autumn period, when the barracouta are thus dependent upon Nyctiphanes for the bulk of their food. A close positive relationship between the availability of barracouta and Nyctiphanes might therefore be expected at those seasons. There is evidence of such a relationship between mean availability (catch per boat-month) of barracouta and mean percentage of barracouta stomachs containing Nyctiphanes, at those seasons, from year to year. For southern Victorian coastal waters both show a downward trend from 1948-49 to 1950-51 and then an upward trend to 1953-54; for eastern Tasmania both show a downward trend (for autumn only) from 1949-50 through 1952-53. The records of catch per boat-month furnish independent evidence that the main variations in this index were effects of availability (population distribution or behaviour) rather than abundance (population size), at least for southern Victoria. It is therefore considered that when scarcity of barracouta occurs in summer and autumn in the coastal fishing areas it may be due to scarcity of Nyctiphanes, forcing the fish to go offshore for this food which is known to be available there. This would take the fish out of range of the fishermen.

The diet of red foxes, Vulpes vulpes L., in Victoria

1973 ◽  
Vol 21 (3) ◽  
pp. 391 ◽  
Author(s):  
BJ Coman
Keyword(s):  
Vulpes Vulpes ◽  
Regional Differences ◽  
Plant Material ◽  
Stomach Contents ◽  
Red Foxes ◽  
Main Food ◽  
Food Items ◽  
Over Time

Stomach contents were examined for 1229 foxes collected in Victoria during 1968-70. Of these, 967 stomachs contained measurable quantities of food. The fox appears to have a very wide dietary range but is predominantly carnivorous. The main food items encountered were rabbits, sheep carrion, and mice. Lesser amounts of native mammals, birds, cold-blooded vertebrates, invertebrates, and plant material were encountered. For many foods, particularly insects, the intake was markedly seasonal. Regional differences in diet were also apparent. Much of the variation in intake of particular foods over time and between regions was explicable in terms of changing availabilities of these foods.

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