scholarly journals Predator-prey mass ratio drives microbial activity under dry conditions inSphagnumpeatlands

2018 ◽  
Vol 8 (11) ◽  
pp. 5752-5764 ◽  
Author(s):  
Monika K. Reczuga ◽  
Mariusz Lamentowicz ◽  
Matthieu Mulot ◽  
Edward A. D. Mitchell ◽  
Alexandre Buttler ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Mass Ratio ◽  
Predator Prey ◽  
Dry Conditions ◽  
Prey Mass

Predator–prey mass ratio revisited: does preference of relative prey body size depend on individual predator size?

2016 ◽  
Vol 30 (12) ◽  
pp. 1979-1987 ◽  
Author(s):  
Cheng‐Han Tsai ◽  
Chih‐hao Hsieh ◽  
Takefumi Nakazawa
Keyword(s):  
Body Size ◽  
Mass Ratio ◽  
Predator Prey ◽  
Predator Size ◽  
Prey Mass

Trophic positions and predator–prey mass ratio of the pelagic food web in the East China Sea and Sea of Japan

2016 ◽  
Vol 67 (11) ◽  
pp. 1692 ◽  
Author(s):  
Seiji Ohshimo ◽  
Hiroshige Tanaka ◽  
Koh Nishiuchi ◽  
Tohya Yasuda
Keyword(s):  
Food Web ◽  
Food Webs ◽  
East China Sea ◽  
Sea Of Japan ◽  
Trophic Position ◽  
Mass Ratio ◽  
The East China Sea ◽  
Predator Prey ◽  
Prey Mass ◽  
Scaled Models

Size-based food webs analysis is essential for understanding food web structure and evaluating the effects of human exploitation on food webs. We estimated the predator–prey mass ratio (PPMR) of the pelagic food web in the East China Sea and Sea of Japan by using the relationships between body mass and trophic position. Trophic position was calculated by additive and scaled models based on nitrogen stable isotope ratios (δ15N). The PPMRs based on additive and scaled models were 5032 (95% confidence interval (CI) 2066–15506) and 3430 (95% CI 1463–10083) respectively. The comparatively high PPMRs could reflect low ecosystem transfer efficiency and high metabolic rate.

Phosphorus changes during the leaching and decomposition of hayed-off pasture plants

1969 ◽  
Vol 20 (4) ◽  
pp. 653 ◽  
Author(s):  
OL Jones ◽  
SM Bromfield
Keyword(s):  
Microbial Activity ◽  
Inorganic Phosphate ◽  
Organic Phosphorus ◽  
The Other ◽  
Other Hand ◽  
Dry Conditions ◽  
Pasture Plants ◽  
Inorganic And Organic

Ground samples of hayed-off pasture plants were decomposed in the laboratory under continuously moist, and intermittently moist and dry, conditions. During the course of decomposition they were leached at different frequencies and the resulting changes in inorganic and organic phosphorus measured. The dissolution of superphosphate and its conversion to organic phosphorus were also studied under some of these conditions.Inorganic phosphate was readily leached from the samples when microbes were inhibited. Microbial activity, on the other hand, largely prevented the loss of inorganic phosphate by leaching from a phalaris sample over a period of 3 months. Intermittent drying increased the amount of phosphate leached from decomposing plants but the leaching frequencies examined had little effect. The percentage of the phosphorus leached from plants varied with the type of material. In all cases less than half was recovered as inorganic phosphate, even after decomposition and leaching for 6 months. When superphosphate granules were leached in the presence of decomposing plants the conversion of fertilizer phosphate to organic phosphorus was small, but the dissolution of phosphate was sometimes retarded. The recycling of phosphate in hayed-off pastures is discussed in the light of these results.

The direct and indirect effects of temperature on a predator–prey relationship

2001 ◽  
Vol 79 (10) ◽  
pp. 1834-1841 ◽  
Author(s):  
Michael T Anderson ◽  
Joseph M Kiesecker ◽  
Douglas P Chivers ◽  
Andrew R Blaustein
Keyword(s):  
Indirect Effects ◽  
Prey Capture ◽  
Prey Size ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Predator Prey ◽  
Prey Mass ◽  
Effects Of Temperature ◽  
Logistic Regression Equation ◽  
Probability Of Capture

Abiotic factors may directly influence community structure by influencing biotic interactions. In aquatic systems, where gape-limited predators are common, abiotic factors that influence organisms' growth rates potentially mediate predator–prey interactions indirectly through effects on prey size. We tested the hypothesis that temperature influences interactions between aquatic size-limited insect predators (Notonecta kirbyi) and their larval anuran prey (Hyla regilla) beyond its indirect effect on prey size. Notonecta kirbyi and H. regilla were raised and tested in predator–prey trials at one of three experimentally maintained temperatures, 9.9, 20.7, or 25.7°C. Temperature strongly influenced anuran growth and predator success; mean tadpole mass over time was positively related to temperature, while the number of prey caught was negatively related. At higher temperatures tadpoles attained greater mass more quickly, allowing them to avoid capture by notonectids. However, the probability of capture is a function of both mass and temperature; temperature was a significant explanatory variable in a logistic regression equation predicting prey capture. For a given prey mass, tadpoles raised in warmer water experienced a higher probability of capture by notonectids. Thus, rather than being static, prey size refugia are influenced directly by abiotic factors, in this case temperature. This suggests that temperature exerts differential effects on notonectid and larval anurans, leading to differences in the probability of prey capture for a given prey mass. Therefore, temperature can influence predator–prey interactions via indirect effects on prey size and direct effects on prey.

scholarly journals Using relative brain size to better understand trophic interactions and phenotypic plasticity of invasive lionfish (Pterois volitans)

2020 ◽  
Author(s):  
McKenna Becker
Keyword(s):  
Body Mass ◽  
Brain Size ◽  
Predation Pressure ◽  
Mass Ratio ◽  
Pterois Volitans ◽  
Predator Prey ◽  
Brain Mass ◽  
Body Mass Ratio ◽  
Relative Brain Size ◽  
The Brain

AbstractPredator-prey dynamics provide critical insight into overall coral reef health. It has been shown that predator-prey relationships link the relative brain size of predators to their prey. Predation pressure forces prey to use decision-making skills that require higher cognition by inspecting and identifying predators and then adjusting their behavior to achieve the highest chance for survival. However, the predation pressure that prey face outweighs the pressure predators face to find prey, resulting in prey having larger relative brain sizes than their predators. There is little data on the relative brain size of fishes with few natural predators such as Pterois volitans. This study compared the brain mass to body mass ratio of Pterois volitans, which have very few natural predators and thus very little predation pressure, to the brain mass to body mass ratio of their prey, possible predators, competitors, and taxonomically similar fish. Lionfish had a significantly smaller relative brain size than their predators, prey, and competitors, but was not significantly smaller than taxonomically similar fish. These results demonstrate that the morphological anti-predator adaptation of venomous spines causes little predation pressure. Thus, lionfish do not use the same cognitive skills as other prey or predators and, in turn, have smaller relative brain sizes.

scholarly journals Estimation of predator-prey mass ratios using stable isotopes: sources of errors

2014 ◽  
Author(s):  
Eric Hertz ◽  
James Robinson ◽  
Marc Trudel ◽  
Asit Mazumder ◽  
Julia K Baum
Keyword(s):  
Stable Isotopes ◽  
Food Web ◽  
North Sea ◽  
Trophic Position ◽  
Trophic Levels ◽  
Environmental Stability ◽  
Food Web Structure ◽  
Predator Prey ◽  
Web Structure ◽  
Prey Mass

In aquatic systems, the ratio of predator mass to prey mass (PPMR) is an important constraint on food web structure, and has been correlated with environmental stability. One common approach of estimating PPMR uses nitrogen stable isotopes (δ15N) as an indicator of trophic position, under the assumption that the discrimination between diet and tissue is constant with increasing diet δ15N (an additive approach). However, recent studies have shown that this assumption may not be valid, and that there is a negative trend between the δ15N of the diet and the discrimination value (a scaled approach). We estimated PPMR for a simulated food web using the traditional additive approach and improved scaled approach, before testing our predictions with isotope samples from a North Sea food web. Our simulations show that the additive approach gives incorrect estimates of PPMR, and these biases are reflected in North Sea PPMR estimates. The extent of the bias is dependent on the baseline δ15N and trophic level sampled, with the greatest differences for samples with low baseline δ15N sampled at lower trophic levels. The scaled approach allows for the comparison of PPMR across varying δ15N baselines and trophic levels, and will refine estimates of PPMR.

A length-based approach to predator–prey relationships in marine predators

2016 ◽  
Vol 73 (4) ◽  
pp. 677-684 ◽  
Author(s):  
Francis Juanes
Keyword(s):  
Niche Breadth ◽  
Prey Size ◽  
Trophic Niche ◽  
Aquatic Environments ◽  
Critical Feature ◽  
Predator Prey ◽  
Marine Predators ◽  
Prey Mass ◽  
Aquatic Predators ◽  
Prey Length

Body size is a critical feature of the ecology of most organisms and has been used to describe and understand predator–prey interactions in both terrestrial and aquatic environments. Most previous studies have used prey mass to examine the relationships between predator size and prey size; however, using prey lengths may provide a different perspective, particularly for gape-limited fishes. Using a large database of predator and prey lengths for marine aquatic predators, I found the expected positive wedge-shaped relationship between predator length and prey length and a negative converging relationship between relative prey length (prey–predator length ratio = a measure of trophic niche breadth) and predator length. Distinct patterns in the size scaling of this measure of trophic niche breadth were identified using quantile regression: converging relationships were common among adults but absent among larvae. This difference suggests contrasting ontogenetic foraging opportunities between adults and larvae: a lack of large relative prey sizes for the largest adult predators, and a greater ability of larvae to include larger prey items in their diet as they grow.

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