Feeding rates of amphipods in boreal lakes: is there a seasonal shift independent of temperature and photoperiod?

AbstractIndustrialization in the Northern Hemisphere has led to warming and pollution of natural ecosystems. We used paleolimnological methods to explore whether recent climate change and/or pollution had affected a very remote lake ecosystem, i.e. one without nearby direct human influence. We compared sediment samples that date from before and after the onset of industrialization in the mid-nineteenth century, from four short cores taken at water depths between 12.1 and 68.3 m in Lake Bolshoe Toko, eastern Siberia. We analyzed diatom assemblage changes, including diversity estimates, in all four cores and geochemical changes (mercury, nitrogen, organic carbon) from one core taken at an intermediate water depth. Chronologies for two cores were established using 210Pb and 137Cs. Sedimentation rates were 0.018 and 0.033 cm year−1 at the shallow- and deep-water sites, respectively. We discovered an increase in light planktonic diatoms (Cyclotella) and a decrease in heavily silicified euplanktonic Aulacoseira through time at deep-water sites, related to more recent warmer air temperatures and shorter periods of lake-ice cover, which led to pronounced thermal stratification. Diatom beta diversity in shallow-water communities changed significantly because of the development of new habitats associated with macrophyte growth. Mercury concentrations increased by a factor of 1.6 since the mid-nineteenth century as a result of atmospheric fallout. Recent increases in the chrysophyte Mallomonas in all cores suggested an acidification trend. We conclude that even remote boreal lakes are susceptible to the effects of climate change and human-induced pollution.

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Male parent birds exert more effort to reproduce in two desert passerines

Avian Research ◽

10.1186/s40657-021-00273-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Donghui Ma ◽

Mengjie Lu ◽

Zhichang Cheng ◽

Xingnan Du ◽

Xiaoyu Zou ◽

...

Keyword(s):

Reproductive Output ◽

Female Parent ◽

Northwest China ◽

Reproductive Behaviour ◽

Male Parent ◽

Hatching Rate ◽

Feeding Rates ◽

Passerine Species ◽

Arid Desert ◽

Habitat Environment

Abstract Background Parental investment by birds is limited by the habitat environment, and a male parent increases its effort to reproduce in birds that live in high-altitude areas. Methods A study of the reproductive behaviour of the Saxaul Sparrow (Passer ammodendri) and the Isabelline Shrike (Lanius isabellinus) was carried out at the Gansu An’xi Extremely Arid Desert National Nature Reserve in northwest China to determine the reproductive input of passerine species in desert habitats. Results In Saxaul Sparrows, compared to the female parent, the male parent exhibited a significantly higher frequency of nest-defense behaviour (chirping and warning) during nesting, hatching and feeding periods. In addition, in comparison to the female parent, the male parent exhibited almost equal frequencies of nesting and incubation but fed nestlings significantly more times. Similar to the male sparrows, the feeding rates of the male Isabelline Shrikes were significantly higher than those of the females. The hatching rate and fledging rate of the Saxaul Sparrow on average in this study were 81.99 and 91.92%, respectively, while those of the shrike were 69.00 and 96.53%, respectively. Conclusions These two different passerine species living in the same desert environment exhibited the same trend in their reproductive investments. Adapting to desert environments is a strategy that may have evolved in passerines where male parent birds put more effort than females into reproduction to ensure high reproductive output.

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In situ feeding rates and grazing impact of zooplankton in a South African temporarily open estuary

Marine Biology ◽

10.1007/s00227-002-0963-x ◽

2003 ◽

Vol 142 (2) ◽

pp. 357-367 ◽

Cited By ~ 25

Author(s):

I. Kibirige ◽

R. Perissinotto

Keyword(s):

South African ◽

Grazing Impact ◽

Feeding Rates ◽

In Situ Feeding

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Longitudinal Axial Flow Rice Thresher Performance Optimization Using the Taguchi Technique

Agriculture ◽

10.3390/agriculture11020088 ◽

2021 ◽

Vol 11 (2) ◽

pp. 88

Author(s):

Mohamed Anwer Abdeen ◽

Abouelnadar Elsayed Salem ◽

Guozhong Zhang

Keyword(s):

Performance Optimization ◽

Feed Rate ◽

Axial Flow ◽

Feeding Rates ◽

Power Requirement ◽

Rotating Speed ◽

Seed Loss ◽

Harvesting Process ◽

Combine Harvesters ◽

Working Device

Combine harvesters are widely used worldwide in harvesting many crops, and they have many functions that cover the entire harvesting process, such as cutting, threshing, separating, and cleaning. The threshing drum is the core working device of the combine harvester and plays an influential role in rice threshing efficiency, threshing power requirement, and seed loss. In this study, two structures of rice threshers (conical-shaped and cylindrical-shaped) were tested and evaluated for performance under different thresher rotating speeds of 1100, 1300, and 1500 rpm and different feeding rates of 0.8, 1.1, and 1.4 kg/s. The experiment was designed using the Taguchi method, and the obtained results were evaluated using the same technique. The thresher structure and operating parameters were assessed and optimized with reference to threshing efficiency, required power, and productivity. The obtained results revealed that increasing thresher rotating speed and the feeding rate positively related to threshing efficiency, power, and productivity. The highest efficiency of 98% and the maximum productivity of 0.64 kg/s were obtained using the conical-shaped thresher under a 1500 rpm rotating speed and a feed rate of 1.4 kg/s, whereas the minimum required power of 5.45 kW was obtained using the conical thresher under a rotating speed of 1100 rpm and a feed rate of 0.8 kg/s.

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