Predator populations differ in their foraging responses to acute seawater acidification

2020 ◽  
Vol 646 ◽  
pp. 69-78
Author(s):  
GM Contolini ◽  
KJ Kroeker ◽  
EP Palkovacs
Keyword(s):  
Current System ◽  
Search Time ◽  
Handling Time ◽  
Prior Exposure ◽  
Source Population ◽  
California Current System ◽  
Seawater Acidification ◽  
Environmental Regimes ◽  
Experimental Acidification ◽  
The Individual

Local adaptation can cause predator populations to vary in traits and their effects on prey, but few studies have tested whether divergent predator populations respond differently to acute environmental stressors. We tested how Nucella dogwhelks from 3 populations with natural exposure to distinct environmental regimes in the California Current System altered consumption of mussel prey (Mytilus californianus) in ambient (pH 8.0, 429 µatm partial pressure of CO2 [pCO2]) and acidified (pH 7.6, 1032 µatm pCO2) seawater. Overall, experimental acidification increased the variation in consumption time observed among populations. We found reduced consumption time for the population that experienced more frequent exposure to low pH conditions in nature but not for populations with less prior exposure. Exposure to acidification also altered the individual components of consumption time—search time and handling time—depending on source population. These results indicate that impaired predator performance is not a universal response to acidification, that predation responses to acute acidification can be population specific, and that individual population responses may relate to prior exposure. Our study highlights how population-specific responses to climate change can lead to differences in ecological effects that may restructure prey communities at local scales.

scholarly journals Reconstruction of Diffusion Coefficients and Power Exponents from Single Lagrangian Trajectories

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 111
Author(s):  
Leonid M. Ivanov ◽  
Collins A. Collins ◽  
Tetyana Margolina
Keyword(s):  
Black Sea ◽  
Diffusion Coefficients ◽  
Current System ◽  
Mean Square Displacement ◽  
California Current ◽  
The Black Sea ◽  
Mean Square ◽  
California Current System ◽  
The Mean ◽  
Non Gaussian

Using discrete wavelets, a novel technique is developed to estimate turbulent diffusion coefficients and power exponents from single Lagrangian particle trajectories. The technique differs from the classical approach (Davis (1991)’s technique) because averaging over a statistical ensemble of the mean square displacement (<X2>) is replaced by averaging along a single Lagrangian trajectory X(t) = {X(t), Y(t)}. Metzler et al. (2014) have demonstrated that for an ergodic (for example, normal diffusion) flow, the mean square displacement is <X2> = limT→∞τX2(T,s), where τX2 (T, s) = 1/(T − s) ∫0T−s(X(t+Δt) − X(t))2 dt, T and s are observational and lag times but for weak non-ergodic (such as super-diffusion and sub-diffusion) flows <X2> = limT→∞≪τX2(T,s)≫, where ≪…≫ is some additional averaging. Numerical calculations for surface drifters in the Black Sea and isobaric RAFOS floats deployed at mid depths in the California Current system demonstrated that the reconstructed diffusion coefficients were smaller than those calculated by Davis (1991)’s technique. This difference is caused by the choice of the Lagrangian mean. The technique proposed here is applied to the analysis of Lagrangian motions in the Black Sea (horizontal diffusion coefficients varied from 105 to 106 cm2/s) and for the sub-diffusion of two RAFOS floats in the California Current system where power exponents varied from 0.65 to 0.72. RAFOS float motions were found to be strongly non-ergodic and non-Gaussian.

scholarly journals Persistent spatial structuring of coastal ocean acidification in the California Current System

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
F. Chan ◽  
J. A. Barth ◽  
C. A. Blanchette ◽  
R. H. Byrne ◽  
F. Chavez ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Current System ◽  
California Current ◽  
Coastal Ocean ◽  
California Current System ◽  
Spatial Structuring

scholarly journals How is the effectiveness of immune surveillance impacted by the spatial distribution of spreading infections?

2015 ◽  
Vol 370 (1675) ◽  
pp. 20140289 ◽  
Author(s):  
Ulrich D. Kadolsky ◽  
Andrew J. Yates
Keyword(s):  
Spatial Distribution ◽  
Immune Surveillance ◽  
Critical Density ◽  
Search Time ◽  
Handling Time ◽  
Mass Action ◽  
Mass Action Kinetics ◽  
Expected Time ◽  
Target Ratio ◽  
Infected Cells

What effect does the spatial distribution of infected cells have on the efficiency of their removal by immune cells, such as cytotoxic T lymphocytes (CTL)? If infected cells spread in clusters, CTL may initially be slow to locate them but subsequently kill more rapidly than in diffuse infections. We address this question using stochastic, spatially explicit models of CTL interacting with different patterns of infection. Rather than the effector : target ratio, we show that the relevant quantity is the ratio of a CTL's expected time to locate its next target (search time) to the average time it spends conjugated with a target that it is killing (handling time). For inefficient (slow) CTL, when the search time is always limiting, the critical density of CTL (that required to control 50% of infections, C * ) is independent of the spatial distribution and derives from simple mass-action kinetics. For more efficient CTL such that handling time becomes limiting, mass-action underestimates C * , and the more clustered an infection the greater is C * . If CTL migrate chemotactically towards targets the converse holds— C * falls, and clustered infections are controlled most efficiently. Real infections are likely to spread patchily; this combined with even weak chemotaxis means that sterilizing immunity may be achieved with substantially lower numbers of CTL than standard models predict.

scholarly journals Surface Stress and Atmospheric Boundary Layer Response to Mesoscale SST Structure in Coupled Simulations of the Northern California Current System

2019 ◽  
Vol 148 (1) ◽  
pp. 259-287
Author(s):  
R. M. Samelson ◽  
L. W. O’Neill ◽  
D. B. Chelton ◽  
E. D. Skyllingstad ◽  
P. L. Barbour ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Stress ◽  
Current System ◽  
California Current ◽  
Heat Fluxes ◽  
Neutral Stability ◽  
Northern California ◽  
Coupling Coefficients ◽  
California Current System ◽  
Northern California Current

Abstract The influence of mesoscale sea surface temperature (SST) variations on wind stress and boundary layer winds is examined from coupled ocean–atmosphere numerical simulations and satellite observations of the northern California Current System. Model coupling coefficients relating the divergence and curl of wind stress and wind to downwind and crosswind SST gradients are generally smaller than observed values and vary by a factor of 2 depending on planetary boundary layer (PBL) scheme, with values larger for smoothed fields on the 0.25° observational grid than for unsmoothed fields on the 12-km model grid. Divergence coefficients are larger than curl coefficients on the 0.25° grid but not on the model grid, consistent with stronger scale dependence for the divergence response than for curl in a spatial cross-spectral analysis. Coupling coefficients for 10-m equivalent neutral stability winds are 30%–50% larger than those for 10-m wind, implying a correlated effect of surface-layer stability variations. Crosswind surface air temperature and SST gradients are more strongly coupled than downwind gradients, while the opposite is true for downwind and crosswind heat flux and SST gradients. Midlevel boundary layer wind coupling coefficients show a reversed response relative to the surface that is predicted by an analytical model; a predicted second reversal with height is not seen in the simulations. The relative values of coupling coefficients are consistent with previous results for the same PBL schemes in the Agulhas Return Current region, but their magnitudes are smaller, likely because of the effect of mean wind on perturbation heat fluxes.

scholarly journals Universities of the Russian Empire in Autobiographies of Historians in the 19th – early 20th Centuries: “Events”, “Actors”, “Stories”

2019 ◽  
Keyword(s):  
Life Experience ◽  
Current System ◽  
Professional Community ◽  
Moral Code ◽  
Teacher Student ◽  
University Life ◽  
Life Path ◽  
The Russian Empire ◽  
The Individual ◽  
The University

The paper provides an analysis of the 19th – early 20th centuries autobiographies by I. Snehyrov, N. Ustrialov, S. Soloviov, K. Bestuzhev-Riumyn, M. Maksymovych, N. Kostomarov, V. Antonovych, M. Drahomanov, V. Semevskyi, etc. Such concepts as «life events», «actors», «stories» act as key notions of the research. This research focuses on the «event» saturation at various stages and different spheres of the university life of memoirists, as well as the peculiarities of interpretation and presentation of the corresponding «events». Particular attention is paid to the analysis of «stories», which are a complete narration and give some «events» the status of «key» or «turning». In addition, the paper analyzes the circle of communication of memoirists (so-called «significant others»), which allows to talk about the relationships in the system «teacher – student», «client – patron», etc. Understanding autobiographical texts as cultural and intellectual constructs influenced by a lot of factors (cultural and historiographic tradition, life experience of a memoirist, etc.), makes it possible to understand more deeply not only the individual «life path» of the university historian, but also the phenomenon of the university as a whole. In particular, the appearance in the autobiographies of historians of the younger generation of reflections on their current system of education, attempts to understand the moral code of «university person», the emphasis on the recognition of their scientific achievements by their colleagues. This is what indicates the beginning of the formation process of a professional community and awareness of the university values.

Sign in / Sign up

Export Citation Format

Share Document