scholarly journals PAPEL DOS PEIXES NA RECICLAGEM DE NUTRIENTES EM RIACHOS TROPICAIS

2021 ◽  
Vol 25 (02) ◽  
pp. 449-463
Author(s):  
Eugenia Zandonà ◽  
◽  
Priscila Oliveira-Cunha ◽  
Beatriz Moreira-Ferreira
Keyword(s):  
Body Size ◽  
Abiotic Factors ◽  
Nutrient Recycling ◽  
Metabolic Theory ◽  
Nitrogen And Phosphorus ◽  
Nutrient Demand ◽  
Mass Balance Models ◽  
Excretion Rates ◽  
And Behavior

Fish can contribute directly and indirectly to nutrient recycling in aquatic environments, affecting community structure and ecosystem processes. Through the excretion of metabolic waste, fish make inorganic nutrients available in the environment that can be used by algae and bacteria. Nitrogen and phosphorus are often limiting nutrients in streams, so fish can be a relevant source of these nutrients. Many factors can influence excretion rates, including diet, body nutrient demand (for reproduction and growth), ontogeny, body size, temperature and other abiotic factors. Currently, two theories propose to explain which factors control excretion rates: 1) The Theory of Ecological Stoichiometry is based on mass balance models and uses the amount of nutrients in the diet and the fish nutrient demand as predictors of excretion rates; and 2) the Metabolic Theory of Ecology that uses body size and temperature as factors that regulate an organism metabolic rates and, thus, its excretion rates. The relative importance of fish as nutrient recyclers in streams varies depending on species intrinsic characteristics and environmental factors. This includes the magnitude of excretion rates from the entire fish community, the nutrient concentration and nutrient input into the stream, the stream nutrient demand and the period of activity and behavior of the fish. For example, species that are abundant in oligotrophic streams have the potential to represent an important source of nutrients. But other peculiarities, such as diet, specific nutrient demands, or migratory behaviors, can make them important sources or sinks of nutrients in a stream. This article reviews studies that address the role of fish as nutrient recyclers and explains the most common techniques used in this type of studies.

Investigating the role of body size, ecology, and behavior in anuran eye size evolution

2019 ◽  
Vol 33 (4) ◽  
pp. 585-598 ◽  
Author(s):  
Chun Hua Huang ◽  
Mao Jun Zhong ◽  
Wen Bo Liao ◽  
Alexander Kotrschal
Keyword(s):  
Body Size ◽  
Eye Size ◽  
Size Evolution ◽  
And Behavior

scholarly journals Trait overdispersion and the role of sociality in the assembly of social spider communities across the Americas

2018 ◽  
Vol 115 (23) ◽  
pp. 6010-6015 ◽  
Author(s):  
Philippe Fernandez-Fournier ◽  
Jennifer Guevara ◽  
Catherine Hoffman ◽  
Leticia Avilés
Keyword(s):  
Body Size ◽  
Group Size ◽  
Abiotic Factors ◽  
Social Systems ◽  
Null Model ◽  
Niche Space ◽  
Social Spider ◽  
The Social ◽  
Size And Morphology

Among the factors that may lead to differences in resource use among closely related species, body size and morphology have been traditionally considered to play a role in community assembly. Here we argue that for animals that live and forage in groups, level of sociality, reflecting differences in group size and cooperative tendencies, can be an additional and powerful dimension separating species in niche space. We compare 50+ communities of the social spider genus Anelosimus across the Americas against a null model that accounts for known effects of biotic and abiotic factors on the distribution of social systems in the genus. We show that these communities are more overdispersed than expected by chance in either or both body size and level of sociality, traits we have previously shown to be associated with differences in resource utilization (prey size, microhabitat, and phenology). We further show that the contribution of sociality to differences in the size of the prey captured is two to three times greater than that of body size, suggesting that changes in group size and cooperative tendencies may be more effective than changes in body size at separating species in niche space.

scholarly journals Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics

2014 ◽  
Vol 11 (11) ◽  
pp. 2939-2960 ◽  
Author(s):  
Y. Li ◽  
G. Gal ◽  
V. Makler-Pick ◽  
A. M. Waite ◽  
L. C. Bruce ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Nutrient Recycling ◽  
Ecosystem Model ◽  
Microbial Loop ◽  
Phytoplankton Growth ◽  
Microbial Interactions ◽  
Trophic Levels ◽  
Nitrogen And Phosphorus ◽  
Available N

Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton has been investigated in Lake Kinneret (Israel) using a coupled hydrodynamic–ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering (i) the role of bacterial mineralisation, (ii) the effect of micrograzer excretion, and (iii) bacterial ability to compete for dissolved inorganic nutrients. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

Direct and indirect effects of fish on pelagic nitrogen and phosphorus availability in oligotrophic Arctic Alaskan lakes

2010 ◽  
Vol 67 (10) ◽  
pp. 1635-1648 ◽  
Author(s):  
Cody R. Johnson ◽  
Chris Luecke ◽  
Stephen C. Whalen ◽  
Mary Anne Evans
Keyword(s):  
Indirect Effects ◽  
Nutrient Recycling ◽  
Zooplankton Biomass ◽  
Trophic Levels ◽  
Arctic Lakes ◽  
Nitrogen And Phosphorus ◽  
Lake Productivity ◽  
Nutrient Excretion ◽  
Significant Difference ◽  
Excretion Rates

The importance of fish nutrient recycling for lake primary production increases with lake productivity. However, fish in low-productivity lakes may have substantial indirect effects on nutrient recycling from lower trophic levels. We measured nutrient excretion rates from fish and zooplankton in oligotrophic Arctic lakes and investigated direct and indirect fish effects on consumer nutrient recycling. Fish nutrient excretion rates were small relative to phytoplankton nutrient demand. Zooplankton excretion, however, supplied 19%–130% and 37%–200% of phytoplankton nitrogen and phosphorus demand, respectively. Fish had a significant effect on zooplankton biomass; in lakes with fish, this was approximately 80% lower than in lakes without fish. The difference in zooplankton biomass was due primarily to a decrease in zooplankton density; no significant difference in average zooplankton size was observed between fish and fishless lakes. Fish also impacted zooplankton community composition; communities in lakes with fish were dominated by copepods compared with cladoceran dominance in lakes without fish. Because of lower zooplankton biomass, lakes with fish showed lower rates of zooplankton nitrogen and phosphorus excretion relative to lakes without fish. Thus, our results support the hypothesis that fish have major indirect effects on lake nutrient cycles, even when direct excretion from fish is minimal.

scholarly journals A numerical analysis of the role of the microbial loop in regulating nutrient stoichiometry and phytoplankton dynamics in a eutrophic lake

2013 ◽  
Vol 10 (12) ◽  
pp. 19731-19772
Author(s):  
Y. Li ◽  
G. Gal ◽  
V. Makler-Pick ◽  
A. M. Waite ◽  
L. C. Bruce ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Nutrient Recycling ◽  
Eutrophic Lake ◽  
Microbial Loop ◽  
Phytoplankton Growth ◽  
Microbial Interactions ◽  
Trophic Levels ◽  
Nitrogen And Phosphorus ◽  
Available N

Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton is investigated in Lake Kinneret (Israel) using a coupled hydrodynamic-ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering: (i) the role of bacterial mineralization, (ii) bacterial ability to compete for dissolved inorganic nutrients, and (iii) the effect of micrograzer excretion. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

Individual Differences in the Name Similarity Effect

2014 ◽  
Vol 35 (2) ◽  
pp. 111-118
Author(s):  
Daniel J. Howard ◽  
Roger A. Kerin
Keyword(s):  
Individual Differences ◽  
Impression Management ◽  
Interactive Effect ◽  
Purchase Intentions ◽  
Brand Attitude ◽  
Self Monitoring ◽  
Similarity Effect ◽  
And Behavior ◽  
Usage Context

The name similarity effect is the tendency to like people, places, and things with names similar to our own. Although many researchers have examined name similarity effects on preferences and behavior, no research to date has examined whether individual differences exist in susceptibility to those effects. This research reports the results of two experiments that examine the role of self-monitoring in moderating name similarity effects. In the first experiment, name similarity effects on brand attitude and purchase intentions were found to be stronger for respondents high, rather than low, in self-monitoring. In the second experiment, the interactive effect observed in the first study was found to be especially true in a public (vs. private) usage context. These findings are consistent with theoretical expectations of name similarity effects as an expression of egotism manifested in the image and impression management concerns of high self-monitors.

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