Temporal and spatial dynamics of predation in a robber fly (Efferia staminea) population (Diptera: Asilidae)

1992 ◽  
Vol 70 (8) ◽  
pp. 1546-1552 ◽  
Author(s):  
Kevin M. O'Neill
Keyword(s):  
Prey Availability ◽  
Spatial Scales ◽  
Large Population ◽  
Spatial Dynamics ◽  
Population Level ◽  
Management Program ◽  
Small Scale ◽  
Generalist Predator ◽  
Robber Flies ◽  
Temporal And Spatial

To determine the effect of short-term temporal and small-scale spatial variation in availability of specific prey groups, field studies of prey use by a population of the robber fly Efferia staminea were undertaken. In one study, the appearance of mating swarms of winged males of the ant Formica subpolita was associated with a rapid increase in the proportion of E. staminea observed feeding, and an increase in the proportion of these ants taken as prey. The change in diet occurred over the same time scale as the change in the activity of the ants. When the swarms were absent from the same area, the fewer E. staminea observed feeding utilized a greater diversity of prey taxa and sizes. The proportion of conspecifics in prey records during swarms of F. subpolita was only one-tenth of that during non-swarm intervals, suggesting that high alternative prey availability decreases the incidence of cannibalism in this species. In the second study, E. staminea used a wider diversity of prey on an area of grassland with native vegetation than on a nearby area of grassland that had been reseeded with the grass Agropyron intermedium as part of a range-management program. In the latter area, a large population of crambine moths supplied a major portion of the robber flies' diet. The results of this population-level study illustrate the fine scale over which the composition of the diet of E. staminea varies, and show that the diet of a generalist predator is a function of the temporal and spatial scales over which sampling occurs. The implications of the data for interpreting the composition of the diet, population dynamics, and impact upon prey communities of robber flies are discussed.

scholarly journals Detailed Patterns of Methane Distribution in the German Bight

2021 ◽  
Vol 8 ◽  
Author(s):  
Ingeborg Bussmann ◽  
Holger Brix ◽  
Götz Flöser ◽  
Uta Ködel ◽  
Philipp Fischer
Keyword(s):  
Spatial Resolution ◽  
German Bight ◽  
Methane Concentration ◽  
Spatial Dynamics ◽  
Methane Flux ◽  
Accurate Estimation ◽  
Small Scale ◽  
Input Concentration ◽  
Temporal And Spatial ◽  
Methane Distribution

Although methane is a widely studied greenhouse gas, uncertainties remain with respect to the factors controlling its distribution and diffusive flux into the atmosphere, especially in highly dynamic coastal waters. In the southern North Sea, the Elbe and Weser rivers are two major tributaries contributing to the overall methane budget of the southern German Bight. In June 2019, we continuously measured methane and basic hydrographic parameters at a high temporal and spatial resolution (one measurement per minute every 200–300 m) on a transect between Cuxhaven and Helgoland. These measurements revealed that the overall driver of the coastal methane distribution is the dilution of riverine methane-rich water with methane-poor marine water. For both the Elbe and Weser, we determined an input concentration of 40–50 nmol/L compared to only 5 nmol/L in the marine area. Accordingly, we observed a comparatively steady dilution pattern of methane concentration toward the marine realm. Moreover, small-scale anomalous patterns with unexpectedly higher dissolved methane concentrations were discovered at certain sites and times. These patterns were associated with the highly significant correlations of methane with oxygen or turbidity. However, these local anomalies were not consistent over time (days, months). The calculated diffusive methane flux from the water into the atmosphere revealed local values approximately 3.5 times higher than background values (median of 36 and 128 μmol m–2 d–1). We evaluate that this occurred because of a combination of increasing wind speed and increasing methane concentration at those times and locations. Hence, our results demonstrate that improved temporal and spatial resolution of methane measurements can provide a more accurate estimation and, consequently, a more functional understanding of the temporal and spatial dynamics of the coastal methane flux.

Algae concentrated by frazil ice: evidence from laboratory experiments and field measurements

1989 ◽  
Vol 1 (4) ◽  
pp. 313-316 ◽  
Author(s):  
D.L. Garrison ◽  
A.R. Close ◽  
E. Reimnitz
Keyword(s):  
Laboratory Experiments ◽  
Spatial Scales ◽  
Field Measurements ◽  
Small Scale ◽  
Natural Setting ◽  
Langmuir Circulation ◽  
Frazil Ice ◽  
Laboratory Results ◽  
Temporal And Spatial ◽  
High Concentrations

A number of studies have suggested that high concentrations of organisms in sea ice may be the result of harvesting and concentration by frazil ice. Laboratory experiments have shown that frazil ice can concentrate organisms from two to four times above levels in the underlying water. The concentrations in nature, however, can be considerably higher. The apparent discrepancy between laboratory results and field observations can be explained by the longer temporal and spatial scales that allow more contact of ice crystals with particles and with one another in the sea. It is also likely that small-scale circulation features, such as Langmuir circulation, enhance the ability of frazil ice to concentrate organisms in a natural setting.

scholarly journals Geocoding Large Population-level Administrative Datasets at Highly Resolved Spatial Scales

2013 ◽  
Vol 18 (4) ◽  
pp. 586-603 ◽  
Author(s):  
Sharon E. Edwards ◽  
Benjamin Strauss ◽  
Marie Lynn Miranda
Keyword(s):  
Spatial Scales ◽  
Large Population ◽  
Population Level ◽  
Administrative Datasets

The value of a broad temporal and spatial perspective in understanding dynamics of kelp forest ecosystems

2016 ◽  
Vol 67 (1) ◽  
pp. 14 ◽  
Author(s):  
Daniel C. Reed ◽  
Andrew R. Rassweiler ◽  
Robert J. Miller ◽  
Henry M. Page ◽  
Sally J. Holbrook
Keyword(s):  
Forest Ecosystems ◽  
Spatial Scales ◽  
Kelp Forest ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Short Term ◽  
Spatial Perspective ◽  
Ecological Responses ◽  
Temporal And Spatial

Many ecological processes play out over longer time scales and larger spatial scales than can be studied in a traditional 2–4-year grant cycle. Uncertainties in future funding hinder efforts to implement comprehensive research programs that integrate coupled time series observations of physical variables and ecological responses, manipulative experiments and synthetic analyses over the long term. Such research is essential for advancing our understanding of ecological responses associated with climate change, and the physical and biological processes that control them. This need is perhaps greatest for ecosystems that display highly dynamic and spatially complex patterns that are difficult to explain with short-term, small-scale studies. Such is the case for kelp forest ecosystems, which often show tremendous spatial and temporal variability in resource supply, consumer control and physical disturbance across spatial scales of metres to hundreds of kilometres and temporal scales of hours to decades. Here we present four examples from the Santa Barbara Coastal Long-term Ecological Research project that demonstrate the value of a broad temporal and spatial perspective in understanding the causes and ecological consequences of short-term local dynamics of giant kelp forests of California, USA.

Quantification of Temporal and Spatial Dynamics of Bean pod mottle virus at Different Spatial Scales

2010 ◽  
Vol 11 (1) ◽  
pp. 36
Author(s):  
E. Byamukama ◽  
A. E. Robertson ◽  
F. W. Nutter
Keyword(s):  
Spatial Scales ◽  
Spatial Dynamics ◽  
The United States ◽  
Mottle Virus ◽  
Field Scale ◽  
Bean Pod Mottle Virus ◽  
Growing Seasons ◽  
Prevalent Virus ◽  
Temporal And Spatial ◽  
Field Plots

Bean pod mottle virus (BPMV) is the most prevalent virus infecting soybean (Glycine max) in the United States; however, the temporal and spatial dynamics in BPMV at varying spatial scales has not been elucidated. To quantify the temporal and spatial dynamics of BPMV at a field scale, a quadrat-based method was developed in which six soybean rows, each consisting of 30-cm-long quadrats, were established within soybean cv. NE3001 field plots (i.e., 150 quadrats per plot) in BPMV-inoculated and non-inoculated plots. Quadrats were sampled by selecting the youngest fully expanded leaflet from each of four plants within each quadrat beginning 25 days after planting, and continued at 8- to 11-day intervals until crop senescence. Leaf sap was extracted from each 4-leaflet (bulked) sample (from each quadrat), and tested for presence of the BPMV by ELISA. Quadrat position (plot, row, and quadrat number) and the date of sampling that each quadrat first tested positive for BPMV was recorded and mapped. The rate of BPMV incidence in 2006 ranged from 0.09 to 0.12 logits/day, indicating that BPMV incidence was doubling every 5.3 to 7.7 days in 2006. Doubling times for BPMV incidence in 2007 were slower, ranging from 17.3 to 34.7 days. Analysis of spatial patterns using ordinary runs revealed that BPMV-infected quadrats were predominantly clustered within both BPMV-inoculated and non-inoculated plots throughout both growing seasons. In addition to within field plot studies, a threeyear statewide disease survey (2005-2007) was conducted in Iowa to quantify county and field scale BPMV prevalence and incidence by systematically selecting 30 plants/soybean field (8 to 16 soybean fields per county). Leaf samples were then tested for BPMV by ELISA and county-level BPMV incidence maps were generated using ArcGIS software. End-of-season BPMV prevalence was 39/96 counties in 2005 (40%), 90/99 counties in 2006 (90.1%), and 74/99 counties in 2007 (74.7%). The incidence of BPMV within Iowa counties ranged from 0 to 100% and BPMV incidence significantly increased statewide from north to south. Spatial autocorrelation (dependence) analysis using Moran's I revealed clustering for BPMV incidence among Iowa counties, indicating that BPMV incidence among counties was not random. The elucidation of the within-field temporal and spatial dynamics of BPMV and the statewide geographic distribution of BPMV in Iowa has important implications with regards to sampling, plant disease forensics, BPMV management, and risk prediction of BPMV. Accepted for publication 28 January 2010. Published 26 May 2010.

scholarly journals Origin of quiet-Sun magnetic fields revealed with Hinode

2012 ◽  
Vol 8 (S294) ◽  
pp. 143-148
Author(s):  
Ryohko Ishikawa
Keyword(s):  
Magnetic Fields ◽  
Spatial Scales ◽  
Small Scale ◽  
Quiet Sun ◽  
Convective Motions ◽  
Temporal And Spatial ◽  
The Relationship

AbstractQuiet-Sun magnetic fields are enigmatic in terms of their properties, and their origin is not well understood. One likely possibility is that they are a consequence of interactions with turbulent convective motions of various temporal and spatial scales. Here we investigate the relationship between small-scale magnetic fields and various convection flows. We demonstrate that in addition to granulation and supergranulation, mesogranulation also plays an important role in structuring quiet-Sun magnetic fields. We also study the vector magnetic fields in the quiet Sun, and propose that emerging granular-scale bipolar loops are major sources of the quiet-Sun magnetic fields.

Temporal and Spatial Scales in Phytoplankton Ecology. Mechanisms, Methods, Models, and Management

1980 ◽  
Vol 37 (5) ◽  
pp. 877-900 ◽  
Author(s):  
Graham P. Harris
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Low Frequency ◽  
Small Scale ◽  
Frequency Variation ◽  
Phytoplankton Ecology ◽  
Variable Environments ◽  
Phytoplankton Communities ◽  
Nonsteady State ◽  
Temporal And Spatial

This article is essentially a review of the temporal and spatial scales of variability in both marine and freshwater planktonic environments and the algal responses to those scales. I assert that there are problems with our present understanding of these scales and the use of inappropriate assumptions concerning the occurrence of steady-state conditions. In a nonsteady-state environment the concepts of limiting nutrients must be changed, and the extrapolation from culture to field conditions is fraught with problems. In this paper I review the evidence for the existence and importance of small-scale, high frequency and large-scale, low frequency variation in the planktonic environment and show that such variation fundamentally affects our understanding of existing processes. Methodology and models must also reflect the true scales of variability which exist. I show that there are, at present, problems with our understanding of planktonic processes which greatly affect our ability to manage water quality. New concepts and models are urgently needed. Finally I propose a new model of community structure and process in variable environments which accounts for the correct 'algal' scales of perturbation and response and allows certain predictions to be made. It is possible to reconcile certain problems and controversies in the literature by the use of such a model. An enhanced ability to manage planktonic systems should result from an improved understanding of the true scales of variability which exist.Key words: lakes, oceans, phytoplankton, communities, nutrients, models, management, eutrophication, fluctuations, scales

Spatial and temporal variation in the structure of estuarine macroinvertebrate assemblages: implications for assessing the health of estuaries

2007 ◽  
Vol 58 (9) ◽  
pp. 866 ◽  
Author(s):  
A. J. Hirst ◽  
R. Kilpatrick
Keyword(s):  
Human Impacts ◽  
Spatial Scales ◽  
Reference Points ◽  
Tidal River ◽  
Spatial And Temporal Variation ◽  
Small Scale ◽  
Spatial Differences ◽  
Spatial Replication ◽  
Temporal And Spatial ◽  
Suitable Reference

As human impacts in estuaries are often pervasive (estuary-wide) and/or pre-existing, the identification of suitable reference points, from which to assess the extent of impacts, is problematic. One solution is to compare potentially degraded estuaries with estuaries deemed to be largely unmodified by human activities. However, there is a perception that individual estuaries are too spatially and temporally dynamic to allow valid comparisons to be made using such an approach. We tested this idea for a commonly used indicator, benthic macroinvertebrates, using a factorial design incorporating both temporal and spatial scales between and within three adjacent meso-tidal river estuaries in northern Tasmania. Variation in macroinvertebrate assemblage structure was analysed using permutational multivariate analysis of variance. Most variance occurred within estuaries (68–82% variance) relative to spatial differences between estuaries (24–14%) corresponding with a strong upstream estuarine gradient and small-scale spatial patchiness. Seasonal variation accounted for 9–4% of total variance indicating that temporal differences were relatively insignificant when contrasted against spatial variability within and between estuaries. We suggest that with sufficient spatial replication at the within estuary-scale, entire estuaries may act as whole reference systems, allowing studies to examine potential impacts within estuaries with spatially diffuse, pre-existing human impacts.

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