Feeding in a Nocturnally active fish, Galaxias brevipinnis, in a New Zealand stream

1989 ◽  
Vol 40 (3) ◽  
pp. 231 ◽  
Author(s):  
GJ Glova ◽  
PM Sagar
Keyword(s):  
New Zealand ◽  
Benthic Invertebrates ◽  
Stomach Contents ◽  
Feeding Habit ◽  
Native Fish ◽  
Selective Feeding ◽  
Chironomid Larvae ◽  
Feeding Periodicity ◽  
Active Fish ◽  
Fish Stomach

To determine the diel feeding periodicity and diet of a lake-inlet population of Galaxias brevipinnis in New Zealand, samples of benthos, drift and fish were collected over a 24-h period in summer. Both numerically and gravimetrically, fish stomach contents revealed that feeding started some time after sunset, peaked towards midnight, and virtually ceased after sunrise. Benthic invertebrates were consumed almost exclusively, with ephemeropterans, trichopterans, and dipterans constituting 95% of the total foods eaten, a major proportion being chironomid larvae. Size of prey eaten compared with size of invertebrates in the benthos differed significantly during the night; this indicated that some size-selective feeding occurred. The benthic feeding habit of Galaxias brevipinnis appears to allow it to forage on relatively small prey during the night, a phenomenon that has been reported for other bottom-dwelling native fish species in New Zealand.

Summer foods of Atlantic walrus, Odobenus rosmarus rosmarus, in northern Foxe Basin, Northwest Territories

1997 ◽  
Vol 75 (7) ◽  
pp. 1166-1175 ◽  
Author(s):  
K. I. Fisher ◽  
R. E. A. Stewart
Keyword(s):  
Benthic Invertebrates ◽  
Stomach Contents ◽  
Male And Female ◽  
Foxe Basin ◽  
Important Prey ◽  
Odobenus Rosmarus ◽  
Serripes Groenlandicus ◽  
Gross Energy ◽  
Odobenus Rosmarus Rosmarus ◽  
Atlantic Walrus

Stomach contents of Atlantic walrus, Odobenus rosmarus rosmarus, taken by Inuit hunters in northern Foxe Basin in July 1987 and 1988 (n = 105) and September 1988 (n = 2) were examined. In July, 20 of 94 stomachs from immature and adult walrus contained > 5 g of food representing 17 prey taxa, including bivalves, gastropods, holothurians, polychaetes, and brachiopods. The bivalve Mya truncata contributed 81.4% of the total gross energy in the diet, with the bivalve Hiatella arctica, holothurians, and the polychaete Nereis sp. contributing 7.5, 3.5, and 2.8%, respectively. The diets of male and female walrus were similar except that females received a significantly (P < 0.05) greater percentage of gross energy in their diet from H. arctica than did males. Walrus less than 3 years old (n = 11) consumed mostly milk, although some benthic invertebrates were eaten. Analysis of the contents of two stomachs collected in September suggested that walrus may feed more intensively in the fall. Mya truncata was again the predominant prey, contributing 59.9% of total gross energy, with the bivalve Serripes groenlandicus (37.9%) replacing H. arctica (0.3%) as the second most important prey.

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.

Accumulation of Mercury by Plankton and Benthic Invertebrates in Riverine Lakes of Northern Manitoba (Canada): Importance of Regionally and Seasonally Varying Environmental Factors

1988 ◽  
Vol 45 (10) ◽  
pp. 1744-1757 ◽  
Author(s):  
Togwell A. Jackson
Keyword(s):  
Organic Matter ◽  
Environmental Factors ◽  
Benthic Invertebrates ◽  
Spring Flood ◽  
Chironomid Larvae ◽  
Decomposition Of Organic Matter ◽  
Preferential Uptake ◽  
Predominant Effect ◽  
Benthic Animals ◽  
Hg Accumulation

Mercury (Hg) concentrations in plankton and benthic invertebrates from riverine lakes of northern Manitoba were generally found to be unrelated, or inversely related, to inorganic and methyl mercury levels and Hg methylation rates in their habitats but were strongly dependent on environmental factors. The relationships suggest that the uptake of Hg by these organisms was controlled largely by suspended and sedimentary Hg-binding substances such as FeOOH, MnOOH, organic matter, sulfides, and clay. The sole exception was midsummer phytoplankton, whose Hg content was a function of Hg levels in local sediments, probably because interference by suspended detritus was minimal; during the spring flood, such interference had a predominant effect. Aeration of lake water by fluvial currents probably enhances the availability of Hg to plankton by promoting decomposition of organic matter and sulfides but decreases the availability of Hg to some benthic animals by causing MnOOH precipitation. FeOOH apparently limits Hg uptake by chironomid larvae but MnOOH limits Hg uptake by oligochaetes, nematodes, and pelecypods, suggesting preferential uptake of certain forms of Hg by particular biological and mineral species. Decreases in temperature may also retard Hg uptake by benthos. Biodilution has no significant effect on Hg accumulation by benthos or plankton.

Studies on the Ecology of the New Zealand Long-finned Eel, Anguilla dieffenbachii Gray

1952 ◽  
Vol 3 (1) ◽  
pp. 32 ◽  
Author(s):  
AMR Burnet
Keyword(s):  
New Zealand ◽  
Population Density ◽  
Mathematical Analysis ◽  
Feeding Habits ◽  
Stomach Contents ◽  
Limiting Factor ◽  
Population Densities ◽  
Baited Traps ◽  
Anguilla Dieffenbachii

Experimental trapping of eels, using carrion-baited traps, was carried out on a number of rivers of various types throughout New Zealand. Where possible, a mathematical analysis has been applied to the trapping results and an estimate of the efficiency obtained. Total trappable population densities of between 30 and 1,368 lb./ac. Were found. An attempt has been made to correlate type of river with the population density. The amount of cover present is apparently the limiting factor. The baited trap takes very few eels of less than 24 in. long and is thus not a very efficient means of keeping a stream free from eels. The feeding habits of the eel are generalized and readily adaptable to most faunas. In most rivers trout occurred only infrequently in the stomach contents.

Diel feeding and prey selection of three size classes of shortfinned eel (Anguilla australis) in New Zealand

1998 ◽  
Vol 49 (5) ◽  
pp. 421 ◽  
Author(s):  
P. M. Sagar ◽  
G. J. Glova
Keyword(s):  
New Zealand ◽  
Prey Selection ◽  
Microhabitat Use ◽  
Night Time ◽  
Fish Prey ◽  
Size Classes ◽  
Anguilla Australis ◽  
Selection Indices ◽  
Feeding Periodicity ◽  
Selection Of

Benthic macroinvertebrates and three size classes of shortfinned eel (Anguilla australis, Anguillidae) were sampled in a lowland New Zealand stream over a 24-h period in summer to investigate diel feeding periodicity and prey selection. Fish of all three size classes fed mostly from post-dusk to dawn, with larger fish tending to consume a greater proportion of their prey during night-time. The number of prey taxa consumed increased with increasing size of fish. Prey selection indices indicated that: (1) the smallest eels (80–100 mm total length, TL) preferentially consumed ostracods (Crustacea) and larvae of Chironomidae (Diptera) and Psilochorema sp. (free-living Trichoptera); (2) medium-sized eels (101–199 mm TL) preferred larvae of Chironomidae, and Costachorema sp., Hydrobiosis sp. and Psilochorema sp.; and (3) large eels (200–300 mm TL) preferred ostracods, Psilochorema sp. and Hudsonema amabilis (cased Trichoptera). Eels of all size classes showed selection for soft-bodied or easily broken prey over those with hard cases which would have been more difficult to digest. There was considerable overlap in the diets of medium and large eels. Differences in the timing of feeding between the three size classes of eel are explained in terms of microhabitat use; differences in diet are explained in terms of prey size, and are also related to eel size.

scholarly journals Population dynamics and feeding ecology of the invasive Caucasian dwarf goby, Knipowitschia caucasica, in a freshwater habitat in Ukraine

2020 ◽  
pp. 26
Author(s):  
Alexander Didenko ◽  
Igor Buzevych ◽  
Yuriy Volikov ◽  
Svitlana Kruzhylina ◽  
Alexander Gurbyk
Keyword(s):  
Population Dynamics ◽  
Littoral Zone ◽  
Diet Composition ◽  
Sampling Site ◽  
Age Groups ◽  
Stomach Contents ◽  
Seasonal Fluctuations ◽  
Chironomid Larvae ◽  
High Diversity ◽  
Two Age Groups

Population dynamics and feeding patterns of invasive Knipowitschia caucasica were studied in the littoral zone of the lower Stugna River. The abundances of this goby showed significant inter-annual and seasonal fluctuations. The studied population of K. caucasica was represented by two age groups (0 and I). Fish die after their first breeding season. In total, 58 prey items were identified in the diet of K. caucasica at the sampling site. The most abundant prey were copepods and cladocerans, while the most frequently encountered prey were copepods and chironomid larvae. Copepods were represented mainly by Cyclopoidae. Cladocerans included 21 taxa, among which the most abundant were Diaphanosoma sp., Acroperus harpae, and Disparalona rostrata; chironomids included 22 taxa, among which the most abundant was Cricotopus sylvestris. The diet composition showed seasonal dynamics, where copepods predominated in January to April and in August-September, chironomid larvae were especially important in May to July, while cladocerans were most important in November-December. The relatively high diversity of both phytophilous and open-bottom-dwelling prey organisms in the stomach contents of K. caucasica indicates that this species fed on a large variety of benthic habitats including among macrophytes and open areas.

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