Temporal dynamics in foraging behavior of a pelagic predator

2005 ◽  
Vol 62 (11) ◽  
pp. 2494-2501 ◽  
Author(s):  
Jennifer M Scheuerell ◽  
Daniel E Schindler ◽  
Mark D Scheuerell ◽  
Kurt L Fresh ◽  
Thomas H Sibley ◽  
...  
Keyword(s):  
Food Webs ◽  
Foraging Behavior ◽  
Time Scales ◽  
Sockeye Salmon ◽  
Temporal Dynamics ◽  
Zooplankton Community ◽  
Theoretical Models ◽  
Trophic Links ◽  
Lake Washington ◽  
Short Time

A paradox exists between common observations of highly complex food webs in nature and prevailing ecological theory suggesting that complex food webs are unstable. Qualities of food webs, such as dynamic trophic links, that were not previously considered in theoretical models have been suggested to stabilize complex food webs and resolve this paradox. Flexible foraging behavior can result in dynamic trophic linkages between a predator and its prey over short time scales. Using 4 years of data on diets of juvenile sockeye salmon (Oncorhynchus nerka) and the zooplankton community from Lake Washington (Seattle, Washington, USA), we determined that juvenile sockeye show dynamic foraging behavior that depends solely on the density of its preferred prey, Daphnia. Juvenile sockeye consumed only Daphnia when their density was greater than 0.4·L–1. Long-term patterns in Daphnia densities demonstrated that for the last 28 years, trophic links between sockeye and the less preferred copepods are eliminated for approximately 6 months of each year when Daphnia is above this switching density threshold. Our data provide a convincing empirical example of the activation and inactivation of trophic links occurring on short time scales as a result of dynamic foraging and help to explain the commonness of high-complexity food webs.

Example Three: Temporal Patterns in Limpet Foraging

2020 ◽  
pp. 73-85
Keyword(s):  
Foraging Behavior ◽  
Time Scales ◽  
Intertidal Zone ◽  
Dynamic State ◽  
Foraging Activity ◽  
State Variable ◽  
Model Animal ◽  
Energy Assimilation ◽  
Slow Passage ◽  
Short Time

This chapter presents a third example application of state- and prediction-based theory (SPT), again involving a behavior originally modeled via dynamic state variable modeling (DSVM). This example also addresses animal foraging, this time a choice of foraging activity. In this case, physiology has more important and interesting effects on behavior: the model animal, like many herbivores, can consume food relatively rapidly but does not assimilate its energy until the food's rather slow passage through a long gut. This leads to uncoupling of foraging behavior and energy assimilation on short time scales. The example is based directly on the DSVM analysis by Santini et al. of foraging behavior in the limpet Cella grata, which feeds by scraping rocks in the intertidal zone.

Spatial–Temporal Dynamics of Early Feeding Demand and Food Supply for Sockeye Salmon Fry in Lake Washington

2004 ◽  
Vol 133 (4) ◽  
pp. 1014-1032 ◽  
Author(s):  
David A. Beauchamp ◽  
Christopher J. Sergeant ◽  
Michael M. Mazur ◽  
Jennifer M. Scheuerell ◽  
Daniel E. Schindler ◽  
...  
Keyword(s):  
Food Supply ◽  
Sockeye Salmon ◽  
Temporal Dynamics ◽  
Early Feeding ◽  
Salmon Fry ◽  
Lake Washington

The Spread of Pollutants from Harbour Sludge Depots

1984 ◽  
Vol 16 (3-4) ◽  
pp. 623-633
Author(s):  
M Loxham ◽  
F Weststrate
Keyword(s):  
Time Scales ◽  
Molecular Diffusion ◽  
Near Field ◽  
Parameter Analysis ◽  
Migration Patterns ◽  
Long Time ◽  
Dilution Effects ◽  
Short Time ◽  
Harbour Sludge

It is generally agreed that both the landfill option, or the civil techniques option for the final disposal of contaminated harbour sludge involves the isolation of the sludge from the environment. For short time scales, engineered barriers such as a bentonite screen, plastic sheets, pumping strategies etc. can be used. However for long time scales the effectiveness of such measures cannot be counted upon. It is thus necessary to be able to predict the long term environmenttal spread of contaminants from a mature landfill. A model is presented that considers diffusion and adsorption in the landfill site and convection and adsorption in the underlaying aquifer. From a parameter analysis starting form practical values it is shown that the adsorption behaviour and the molecular diffusion coefficient of the sludge, are the key parameters involved in the near field. The dilution effects of the far field migration patterns are also illustrated.

scholarly journals Impact of tumor-parenchyma biomechanics on liver metastatic progression: a multi-model approach

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yafei Wang ◽  
Erik Brodin ◽  
Kenichiro Nishii ◽  
Hermann B. Frieboes ◽  
Shannon M. Mumenthaler ◽  
...  
Keyword(s):  
Time Scales ◽  
Constitutive Relations ◽  
Elastic Tissue ◽  
Metastatic Progression ◽  
Patient Death ◽  
Metastatic Growth ◽  
Tumor Parenchyma ◽  
Short Time ◽  
Model Approach

AbstractColorectal cancer and other cancers often metastasize to the liver in later stages of the disease, contributing significantly to patient death. While the biomechanical properties of the liver parenchyma (normal liver tissue) are known to affect tumor cell behavior in primary and metastatic tumors, the role of these properties in driving or inhibiting metastatic inception remains poorly understood, as are the longer-term multicellular dynamics. This study adopts a multi-model approach to study the dynamics of tumor-parenchyma biomechanical interactions during metastatic seeding and growth. We employ a detailed poroviscoelastic model of a liver lobule to study how micrometastases disrupt flow and pressure on short time scales. Results from short-time simulations in detailed single hepatic lobules motivate constitutive relations and biological hypotheses for a minimal agent-based model of metastatic growth in centimeter-scale tissue over months-long time scales. After a parameter space investigation, we find that the balance of basic tumor-parenchyma biomechanical interactions on shorter time scales (adhesion, repulsion, and elastic tissue deformation over minutes) and longer time scales (plastic tissue relaxation over hours) can explain a broad range of behaviors of micrometastases, without the need for complex molecular-scale signaling. These interactions may arrest the growth of micrometastases in a dormant state and prevent newly arriving cancer cells from establishing successful metastatic foci. Moreover, the simulations indicate ways in which dormant tumors could “reawaken” after changes in parenchymal tissue mechanical properties, as may arise during aging or following acute liver illness or injury. We conclude that the proposed modeling approach yields insight into the role of tumor-parenchyma biomechanics in promoting liver metastatic growth, and advances the longer term goal of identifying conditions to clinically arrest and reverse the course of late-stage cancer.

Variations in the depositional fluxes of cosmogenic beryllium on short time scales

2011 ◽  
Vol 45 (17) ◽  
pp. 2836-2841 ◽  
Author(s):  
M. Mann ◽  
J. Beer ◽  
F. Steinhilber ◽  
J.A. Abreu ◽  
M. Christl ◽  
...  
Keyword(s):  
Time Scales ◽  
Short Time

Horizontal and vertical movements of telemetered rainbow trout (Oncorhynchus mykiss) in Lake Washington

1995 ◽  
Vol 73 (1) ◽  
pp. 146-153 ◽  
Author(s):  
Eric J. Warner ◽  
Thomas P. Quinn
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Average Velocity ◽  
Sockeye Salmon ◽  
Depth Distribution ◽  
Prey Species ◽  
Nearshore Zone ◽  
Vertical Movements ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Lake Washington

In summer and fall 1989, six rainbow trout (Oncorhynchus mykiss) were tracked in Lake Washington with ultrasonic transmitters for a total of 349 h to determine their movements in relation to the distribution of possible prey species. The trout moved primarily in the nearshore area at an average velocity of 12.4 cm/s (~ 0.25–0.3 body lengths/s). Five of the six fish made one more rapid (>1 body lengths/s) excursion across the lake, then continued moving in the nearshore zone. The trout were generally inactive, staying close (<50 m) to shore at night, and became more active near dawn; however, the highest average velocities were at dusk. They spent over 90% of their time in the top 3 m of the water column and 10% in brief (2 min), shallow (mean 6.6 m) dives. Dives occurred most frequently at dawn and during the day (0.8/h), less often near dusk (0.5/h), and seldom at night (0.1/h). The depth distribution and movement patterns suggest that the trout were feeding on Daphnia pulicaria during the day, in both nearshore and offshore areas, supplementing this diet with nearshore fishes such as prickly sculpins (Cottus asper). Predation on pelagic planktivores (longfin smelt, Spirinchus thaleichthyes, and juvenile sockeye salmon, Oncorhynchus nerka) was unlikely because the trout were primarily found nearshore and near the surface, whereas the planktivores are primarily offshore and closer to the bottom.

scholarly journals Nonlinearities of heart rate variability in animal models of impaired cardiac control: contribution of different time scales

2017 ◽  
Vol 123 (2) ◽  
pp. 344-351 ◽  
Author(s):  
Luiz Eduardo Virgilio Silva ◽  
Renata Maria Lataro ◽  
Jaci Airton Castania ◽  
Carlos Alberto Aguiar Silva ◽  
Helio Cesar Salgado ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Time Scales ◽  
Multiscale Entropy ◽  
Time Frequency ◽  
Cardiac Control ◽  
Long Time ◽  
Nonlinear Features ◽  
Short Time

Heart rate variability (HRV) has been extensively explored by traditional linear approaches (e.g., spectral analysis); however, several studies have pointed to the presence of nonlinear features in HRV, suggesting that linear tools might fail to account for the complexity of the HRV dynamics. Even though the prevalent notion is that HRV is nonlinear, the actual presence of nonlinear features is rarely verified. In this study, the presence of nonlinear dynamics was checked as a function of time scales in three experimental models of rats with different impairment of the cardiac control: namely, rats with heart failure (HF), spontaneously hypertensive rats (SHRs), and sinoaortic denervated (SAD) rats. Multiscale entropy (MSE) and refined MSE (RMSE) were chosen as the discriminating statistic for the surrogate test utilized to detect nonlinearity. Nonlinear dynamics is less present in HF animals at both short and long time scales compared with controls. A similar finding was found in SHR only at short time scales. SAD increased the presence of nonlinear dynamics exclusively at short time scales. Those findings suggest that a working baroreflex contributes to linearize HRV and to reduce the likelihood to observe nonlinear components of the cardiac control at short time scales. In addition, an increased sympathetic modulation seems to be a source of nonlinear dynamics at long time scales. Testing nonlinear dynamics as a function of the time scales can provide a characterization of the cardiac control complementary to more traditional markers in time, frequency, and information domains. NEW & NOTEWORTHY Although heart rate variability (HRV) dynamics is widely assumed to be nonlinear, nonlinearity tests are rarely used to check this hypothesis. By adopting multiscale entropy (MSE) and refined MSE (RMSE) as the discriminating statistic for the nonlinearity test, we show that nonlinear dynamics varies with time scale and the type of cardiac dysfunction. Moreover, as complexity metrics and nonlinearities provide complementary information, we strongly recommend using the test for nonlinearity as an additional index to characterize HRV.

A BARGAIN WITH NATURE

PEDIATRICS ◽  
1978 ◽  
Vol 62 (6) ◽  
pp. 1035-1035
Author(s):  
R. J. H.
Keyword(s):  
Nervous System ◽  
Time Scales ◽  
Genetic Information ◽  
Human Species ◽  
Genetic Inheritance ◽  
New Learning ◽  
Short Time

Humans have a longer childhood relative to our lifespan than any other species. This provides immense plasticity-ability to learn from their environment and their culture. Most organisms on Earth depend on their genetic information which is prewired into their nervous system. While our behavior is still significantly controlled by our genetic inheritance, we have, through our brains, a much richer opportunity to blaze new behavioral and cultural pathways on short time scales. We have made a bargain with nature; our children will be difficult to raise, but their capacity for new learning will greatly enhance the chances of survival of the human species.

Attempts to Reconcile the Long and the Short-Time Scales in Cosmogony

Science ◽  
1935 ◽  
Vol 82 (2116) ◽  
pp. 53-53
Author(s):  
Paul S. Epstein
Keyword(s):  
Time Scales ◽  
Short Time
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