Food Assimilation Efficiency as a Function of Temperature and Meal Size in Larvae of Chaoborus trivittatus (Diptera: Chaoboridae)

10.2307/4034 ◽  
1981 ◽  
Vol 50 (1) ◽  
pp. 103 ◽  
Author(s):  
Louis A. Giguere
Keyword(s):  
Assimilation Efficiency ◽  
Meal Size ◽  
Food Assimilation

scholarly journals Specific dynamic action, apparent assimilation efficiency, and digestive rate in an arboreal pitviper, Trimeresurus stejnegeri stejnegeri

2008 ◽  
Vol 86 (10) ◽  
pp. 1139-1151 ◽  
Author(s):  
Tein-Shun Tsai ◽  
How-Jing Lee ◽  
Ming-Chung Tu
Keyword(s):  
Assimilation Efficiency ◽  
Specific Dynamic Action ◽  
Meal Size ◽  
Digestive Physiology ◽  
Postprandial Metabolism ◽  
Preferred Temperature ◽  
Time To Peak ◽  
Dynamic Action ◽  
Effects Of Temperature ◽  
Arboreal Snakes

The major aims of this study were to assess the effects of temperature (15–35 °C) and meal size (less than 30% snake mass) on the metabolism and digestive physiology of Trimeresurus stejnegeri stejnegeri Schmidt, 1925 and to compare the results with those of terrestrial snakes. Specific dynamic action (SDA), peak Vo2, and scope of peak Vo2 increased with meal size. Temperature had little effect on SDA. With regression analysis, we found that baseline metabolic rates of T. s. stejnegeri were generally smaller than that for frequent feeders and larger than that for infrequent feeders. We generalized three types of SDA profiles among T. s. stejnegeri and terrestrial snakes (including frequent and infrequent feeders). Trimeresurus stejnegeri stejnegeri had a more shallow and extended profile of postprandial metabolism, which did not support our hypothesis that the pace of digestive metabolism of arboreal snakes is faster than that of terrestrial snakes. The apparent assimilation efficiency (range 0.698–0.884) was significantly lower at 15 °C. At the preferred temperature (26.5–28.8 °C) for a postprandial 50 g snake, the simulated ratios of four parameters (time to peak Vo2, first defecation time, gastric digestion time, and final defecation time) to SDA duration approximated 0.2, 0.5–0.7, 0.7, and 1.1, respectively.

Thermal dependence of food assimilation and locomotor performance in juvenile blue-tailed skinks, Eumeces elegans

2007 ◽  
Vol 57 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Yi-Xin Bao ◽  
Wei-Guo Du ◽  
Lin Shu ◽  
Yi-Wei Lu
Keyword(s):  
Food Intake ◽  
Thermal Sensitivity ◽  
Eastern China ◽  
Assimilation Efficiency ◽  
Age Difference ◽  
Locomotor Performance ◽  
Thermal Dependence ◽  
Physiological Performance ◽  
Effects Of Temperature ◽  
Food Assimilation

AbstractVariation in the physiological performance and behaviour of ectotherms as a result of changes in body temperature can affect important life-history traits. Studies investigating the effects of temperature on physiological performance and behaviour have thus clear ecological significance. We captured juvenile blue-tailed skinks, Eumeces elegans, from a population in Zhejiang, eastern China, and determined the effects of temperature on their food assimilation and locomotor performance. Food intake of the juveniles generally increased with increase in temperatures within the range of 24-30°C and decreased at higher temperatures. The temperature significantly affected the apparent digestive coefficient (ADC) and the assimilation efficiency (AE) of juveniles; the ADC and AE of the skinks at 32°C were higher than those of skinks at other temperatures. The sprint speed increased with increase in temperature within the range of 12-32°C and decreased at higher temperatures. These results suggest the patterns of thermal sensitivity may differ in various functional performances, and hence support the 'multiple optima hypothesis', which suggests that no specific temperature maximises all functional performance. In addition, this study indicates significant between-age difference in thermal physiology by comparing our data with those on adult skinks, including different thermal sensitivity of AE, and different ranges of thermal-performance breadth for food intake and locomotor performance between juvenile and adult E. elegans.

Biomagnification of methylmercury in a marine plankton ecosystem

2020 ◽  
Author(s):  
Peipei Wu ◽  
Emily Zakem ◽  
Stephanie Dutkiewicz ◽  
Yanxu Zhang
Keyword(s):  
Microbial Community ◽  
Food Webs ◽  
Ecological Model ◽  
Assimilation Efficiency ◽  
Trophic Transfer ◽  
Trophic Levels ◽  
Sensitivity Analyses ◽  
Large Species ◽  
Marine Plankton ◽  
Food Assimilation

<p>Methylmercury is greatly bioconcentrated and biomagnified in marine plankton ecosystems, and these communities form the basis of marine food webs. Therefore, evaluating the potential exposure of methylmercury to higher trophic levels, including humans, requires a better understanding of its distribution in the ocean and the factors that control its biomagnification. In this study, a coupled physical/ecological model was used to simulate the trophic transfer of monomethylmercury (MMHg) in a marine plankton ecosystem. The model includes phytoplankton, a microbial community, herbivorous zooplankton (HZ), and carnivorous zooplankton (CZ). The model captured both shorter food chains in oligotrophic regions, with small HZ feeding on small phytoplankton, and longer chains in higher nutrient conditions, with larger HZ feeding on larger phytoplankton and larger CZ feeding on larger HZ. In the model, trophic dilution occurred in the food webs that involved small zooplankton, as the grazing fluxes of small zooplankton were insufficient to accumulate more MMHg in themselves than in their prey. The model suggested that biomagnification was more prominent in large zooplankton and that the microbial community played an important role in the trophic transfer of MMHg. Sensitivity analyses showed that with increasing body size, the sensitivity of the trophic magnification ratio to grazing, mortality rates, and food assimilation efficiency (AE<sub>C</sub>) increased, while the sensitivity to excretion rates decreased. More predation or a longer zooplankton lifespan may lead to more prominent biomagnification, especially for large species. Because lower AE<sub>C</sub> resulted in more predation, modeled ratios of MMHg concentrations between large CZ and HZ doubled when the AE<sub>C</sub> decreased from 40% to 10%. This suggested that the biomagnification of large zooplankton was particularly sensitive to food assimilation efficiency.</p>

Effect of temperature on physiology and bioenergetics of adult Harris mud crab Rhithropanopeus harrisii (Gould, 1841) from the southern Baltic Sea

2014 ◽  
Vol 43 (3) ◽  
Author(s):  
Joanna Hegele-Drywa ◽  
Monika Normant
Keyword(s):  
Production Efficiency ◽  
Assimilation Efficiency ◽  
Ammonia Excretion ◽  
Point Of View ◽  
Effect Of Temperature ◽  
Adult Males ◽  
Mud Crab ◽  
Rhithropanopeus Harrisii ◽  
Physiological Processes ◽  
Food Assimilation

AbstractRates of physiological processes and bioenergetics of the Harris mud crab Rhithropanopeus harrisii were determined during a 7-day experiment on adult males (mean wet weight 0.83 ± 0.16 g) exposed to temperatures of 15°C and 20°C (S = 7). The results show that the change in temperature by 5°C caused detectable changes in locomotor activity, food consumption and faeces production and significant (p < 0.05) changes in metabolic rates. Food assimilation efficiency and the ammonia excretion rate did not change significantly (p > 0.05). The energy expended on metabolic processes was similar at both temperatures (15°C and 20°C) and amounted to 17.7 ± 6.4% and 16.7 ± 4.3% of the assimilated energy, respectively. Similar values were obtained for net production efficiency K2 (P/A) at 15°C and 20°C, i.e. 80.4 ± 22.4% and 82.9 ± 9.7%, respectively. The amount of energy available for production was 2-fold higher at a temperature of 20°C than at 15°C and amounted to 103.69 ± 25.61 and 206.40 ± 20.76 J d−1g−1 wet wt, respectively. The results show that from the bioenergetic point of view, higher experimental temperature is more “profitable” for adult R. harrisii specimens because it provides better conditions for the growth and reproduction.

scholarly journals Secondary Metabolite Emodin Increases Food Assimilation Efficiency of Yellow-Vented Bulbuls (Pycnonotus Xanthopygos)

The Auk ◽  
2003 ◽  
Vol 120 (2) ◽  
pp. 411-417
Author(s):  
Ella Tsahar ◽  
Jacob Friedman ◽  
Ido Izhaki
Keyword(s):  
Food Intake ◽  
Secondary Metabolites ◽  
Secondary Metabolite ◽  
Retention Time ◽  
Dry Matter ◽  
Assimilation Efficiency ◽  
Time Interval ◽  
Mass Coefficient ◽  
Food Assimilation ◽  
Feeding Bout

Abstract We studied the effect of the secondary metabolite emodin on food intake, food assimilation mass coefficient (AMC), feeding bout rate, and defecation rate in a frugivorous bird, the Yellow-vented Bulbul (Pycnonotus xanthopygos). Emodin is found in the ripe fruits of Mediterranean buckthorn (Rhamnus alaternus), which is commonly eaten by P. xanthopygos. Emodin (0.005 and 0.01% wet mass) increased dry matter AMC by 8–10% after isolating the effect of food intake. At a concentration of 0.001%, emodin increased the AMC of nitrogen, fat, and organic remains (mainly carbohydrates and proteins). Apart from emodin, fruits of R. alaternus contain a variety of secondary metabolites that may interact with each other and influence bird digestion. Artificial food laced with crude Rhamnus fruit extract increased food intake and dry matter AMC. Emodin (0.01% wet mass) increased the average time between defecations, but did not affect the time interval between feeding bouts nor the average amount consumed per feeding bout. We speculate that emodin increases food retention time. Longer retention time may explain the observed increase in AMC. Our results suggest that sometimes secondary metabolites in ripe fruit may not be detrimental to frugivores and the presence of emodin in the pulp of ripe buckthorn fruits might be selectively adaptive to the plant.

Pinniped diets inferred from scats: analysis of biases in prey occurrence

2003 ◽  
Vol 81 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Matías Arim ◽  
Daniel E Naya
Keyword(s):  
Empirical Studies ◽  
Assimilation Efficiency ◽  
Size Variation ◽  
Meal Size ◽  
Large Prey ◽  
Ecosystem Monitoring ◽  
Scat Analysis ◽  
Small Prey ◽  
Prey Mass ◽  
Resource Dynamics

The diets of pinnipeds have often been used to study their ecology and resource dynamics and in ecosystem monitoring. Scat analysis is now the most widely used method of inferring the diets of pinnipeds. Using a mathematical model the present study explores the expected biases in prey occurrence that are related to prey mass, proportion of loss of remains, predator assimilation efficiency, size of the scats collected, and meal size. With the exception of meal size, variation in parameters implied variation in the probability of biases in prey occurrence. Biases were asymmetric among prey sizes, but in contrast with previous ideas, the results indicate that small prey have smaller biases than large ones do. Furthermore, the number of scats required to detect a large prey was notably larger than that needed to detect a small prey with the same occurrence. The present study is not limited to a particular pinniped or prey species, so it has the potential to represent a general framework for interpreting the results of scat analysis in pinnipeds. The model complements empirical studies, advancing our comprehension of biases associated with prey occurrence in dietary studies of pinnipeds.

Variation in assimilation efficiency and digestive efficiency of captive harp seals (Phoca groenlandica) on different diets

1997 ◽  
Vol 75 (8) ◽  
pp. 1285-1291 ◽  
Author(s):  
John W. Lawson ◽  
Edward H. Miller ◽  
Elizabeth Noseworthy
Keyword(s):  
Atlantic Cod ◽  
Relative Concentration ◽  
Assimilation Efficiency ◽  
Clupea Harengus ◽  
Meal Size ◽  
Food Type ◽  
Digestive Efficiency ◽  
Greenland Halibut ◽  
Arctic Cod ◽  
Phoca Groenlandica

Digestive efficiency (DE) is influenced by many factors including food type or quality. Assimilation efficiency (AE) and DE of 12 captive harp seals (Phoca groenlandica) were estimated for five prey types in large outdoor seawater tanks. In trials of > 9 days' duration, the seals were fed Atlantic cod (Gadus morhua), Arctic cod (Boreogadus saida), Greenland halibut (Reinhardtius hippoglossoides), Atlantic herring (Clupea harengus), and capelin (Mallotus villosus). Fish were marked with inert tracers so that faecal samples could be matched to individual animals. AE (digestibility of dry matter) was estimated from the relative concentration of Mn2+ in food and faeces. DE (digestible energy) was estimated from the relative concentrations of both Mn2+ and energy in food and faeces. AE and DE values were high, but varied among the fish species (DE: Atlantic cod 93.5%; Arctic cod 93.5%; halibut 94.7%; capelin 95.7%; herring 96.6%). Both estimates of digestive efficiency were positively correlated with prey energy density. For most prey, AE and DE were not correlated with meal size, number of prey in a meal, size of prey, or seal body mass. However, digestive efficiency was greater in seals fed smaller Atlantic cod, or meals of greater mass. Quantifying estimates of digestive efficiency is important for formulating energy-based population consumption models, and so should be improved. It is recommended that more pinniped species be studied in captivity, that experiments last longer, and that the number of individuals studied be increased so that individual differences can be investigated.

Mandibular Protractions and Their Correlation with Meal Size in Juvenile Thai Snakes During Ingestion of Rodent Prey

2011 ◽  
Vol 4 (1) ◽  
pp. 31-33
Author(s):  
Merel J. Cox ◽  
David Chiszar ◽  
Hobart M. Smith
Keyword(s):  
Body Weight ◽  
Body Length ◽  
Meal Size ◽  
Allometric Growth ◽  
Rodent Prey

Nine neonatal and juvenile snakes, four vipers and five nonvipers, were fed rodent meals varying in size, expressed as percent of snake body weight. The number of mandibular protractions and the time to complete swallowing were recorded, with both measures increasing linearly as a function of meal size. These young snakes routinely swallowed meals that were 50% of body weight, and ranged up to 80%, far higher than meals reported by previous workers studying adult vipers (36.4%) and nonvipers (18.4%). Furthermore, the slopes of regressions relating mandibular protractions to meal size in all of our snakes were lower than comparable slopes for adult vipers or nonvipers. We hypothesized that the relatively long and wide skulls of young snakes (i.e., as proportion of body length) were responsible for these ingestive accomplishments, with negative allometric growth being responsible for performance changes during ontogeny.

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