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.

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.

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.

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.

Application of RBF-STARMA Model in Shipping Flow Forecasting

2010 ◽  
Vol 108-111 ◽  
pp. 893-897 ◽  
Author(s):  
Hong Qiong Huang ◽  
Shu Lan Lin ◽  
Tian Hao Tang ◽  
Ji Fang Li
Keyword(s):  
Neural Network ◽  
Hybrid Model ◽  
Spatial Data ◽  
Large Scale ◽  
Linear Trend ◽  
Moving Average ◽  
Original Data ◽  
Spatial And Temporal Variation ◽  
Small Scale ◽  
Temporal And Spatial

Based on the idea of the neural network, intelligent computing methods are used to analyze temporal and spatial data. We present the temporal and spatial autocorrelation moving average (STARMA) model based on the in-depth systematic study on time sequence of hybrid model. Firstly this paper uses radial basis function neural network to extract the temporal and spatial sequence which is non-stationary caused by large-scale non-linear trend, secondly this paper presents STARMA modeling of small-scale random spatial and temporal variation. Comparative analysis between the original data and the forecasting data shows that proposed hybrid model has better performance of fitting and generalization.

Optimising occupancy models and detection probability for conservation monitoring in a forest-dwelling small mammal

2019 ◽  
Author(s):  
Fraser John Combe ◽  
Jonathan S Ellis ◽  
Simone Bullion ◽  
Paul Chanin ◽  
Phillip C Wheater ◽  
...  
Keyword(s):  
Small Mammal ◽  
Detection Probability ◽  
Spatial Scales ◽  
Spatial And Temporal Variation ◽  
Sampling Effort ◽  
Occupancy Models ◽  
Effective Population ◽  
Temporal And Spatial ◽  
Elusive Species ◽  
Hazel Dormouse

The ability to determine the survey effort required to detect species presence is critical for the conservation of populations in order to monitor changes in distribution or abundance, a challenge for rare and elusive species. While designing an effective population survey may be of concern to scientists, it may also be a legal requirement for protected species. We analysed how spatial and temporal variation in sampling effort impacts detection probability in the hazel dormouse (Muscardinus avellanarius), a small mammal that naturally occurs at low density in forest habitat. We used presence and absence data from 144 sites in England, UK. We found that detection probability was strongly affected by survey intensity, with a 37.5% increase in detection probability when sampling effort was increased from 16 to 50 nest tubes per site. We also show that detection probability is highly temporally dependent; monitoring early in the year results in low detection probability (21%-53%; April-June), whilst detection dramatically increased later in the year (89%; September). Our results suggest that variation in detection probability can be complex and influenced by effects at temporal and spatial scales, and by sampling effort. We show that sampling effort can be minimised depending on seasonal variation in detection probability, however this is likely to be species and method dependent.

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 variability in elemental composition of otoliths: implications for determining stock identity and connectivity of populations

2002 ◽  
Vol 59 (4) ◽  
pp. 669-679 ◽  
Author(s):  
Bronwyn M Gillanders
Keyword(s):  
Temporal Variation ◽  
Elemental Composition ◽  
Juvenile Fish ◽  
Spatial And Temporal Variation ◽  
Otolith Chemistry ◽  
Temporal And Spatial Variability ◽  
Spatial Differences ◽  
Elemental Fingerprint ◽  
Temporal And Spatial ◽  
Over Time

Interannual variability in elemental composition of otoliths may confound spatial interpretations. The elemental fingerprints of otoliths of juvenile fish were determined for fish collected from 12 to 15 estuaries in each of three consecutive recruitment years to determine temporal variation in otolith chemistry for each estuary. It was also examined whether there is overlap in elemental fingerprints of fish collected in different years and from different estuaries that may confound subsequent spatial comparisons. Significant differences in otolith chemistry were found among years for individual elements (lithium, manganese, strontium, and barium) and for multi-element fingerprints. Some estuaries showed large variation in multi-element fingerprints among years, whereas others showed little variation among years. There was some overlap of elemental fingerprints of different estuaries, but these were not always for fish collected in the same year. The significant spatial and temporal variation in elemental fingerprints meant that it was possible to confound spatial differences with temporal differences. Therefore, if the natal estuary of the adults is to be determined, a library of elemental fingerprints needs to be built up over time for each estuary rather than a single year-class of juveniles being used as the elemental fingerprint for a number of year-classes of adults.

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 variability in diet, condition and growth of juvenile plaice (Pleuronectes platessa) at sandy beach nursery grounds on the south-west coast of Ireland

2010 ◽  
Vol 91 (6) ◽  
pp. 1215-1223 ◽  
Author(s):  
F. De Raedemaecker ◽  
J. Keating ◽  
D. Brophy ◽  
I. O'Connor ◽  
D. Mc Grath
Keyword(s):  
Habitat Quality ◽  
Large Scale ◽  
Spatial Scales ◽  
Condition Index ◽  
Spatial And Temporal Variation ◽  
Small Scale ◽  
Suitable Habitat ◽  
Pleuronectes Platessa ◽  
Wide Range ◽  
South West Coast

Characterization of suitable habitat for settlement of juvenile flatfish is important for the management of nursery areas. Food availability is one important determinant of habitat quality that can affect the condition and growth, and thus survival, of flatfish. Spatial and temporal variation in diet has been widely studied for several species of flatfish. However, levels of intraspecific variation in diet at small spatial scales are relatively unknown, with most studies focusing only on large scale variability. This study investigates how diet, growth and condition of juvenile plaice, Pleuronectes platessa, varies over two spatial scales (10s of kilometres and 100s of metres). Juvenile plaice were collected from three beaches and from three replicate hauls on each beach using a beach seine in September 2007 and 2008. Gut content analyses of 108 juvenile plaice within the size-range of 70–90 mm were carried out. Diet composition in plaice guts differed among beaches and hauls suggesting that food abundance and availability differed at both spatial scales. A significant positive correlation was observed between a morphological condition index and the prey diversity in the gut. This suggests that fish which specialize on a limited number of prey items (perhaps due to a greater abundance of certain prey) may do better than fish which feed on a wide range of prey types. Significant differences in condition were observed between hauls and between beaches, while recent and total otolith growth varied between beaches but not between hauls. The results highlight the importance of considering small scale variation when attempting to link habitat quality to feeding, growth and condition of juvenile flatfish.

Präzisions-Forstwirtschaft – was ist das? | Precision forestry – what's that?

2007 ◽  
Vol 158 (8) ◽  
pp. 235-242 ◽  
Author(s):  
Hans Rudolf Heinimann
Keyword(s):  
Business Processes ◽  
Spatial Scales ◽  
Supply Chain Coordination ◽  
Sensor Technology ◽  
Small Scale ◽  
Soil Physics ◽  
Coordination Problem ◽  
Precision Engineering ◽  
Precision Forestry ◽  
And Control

The term «precision forestry» was first introduced and discussed at a conference in 2001. The aims of this paper are to explore the scientific roots of the precision concept, define «precision forestry», and sketch the challenges that the implementation of this new concept may present to practitioners, educators, and researchers. The term «precision» does not mean accuracy on a small scale, but instead refers to the concurrent coordination and control of processes at spatial scales between 1 m and 100 km. Precision strives for an automatic control of processes. Precision land use differs from precision engineering by the requirements of gathering,storing and managing spatio-temporal variability of site and vegetation parameters. Practitioners will be facing the challenge of designing holistic, standardized business processes that are valid for whole networks of firms,and that follow available standards (e.g., SCOR, WoodX). There is a need to educate and train forestry professionals in the areas of business process re-engineering, computer supported management of business transactions,methods of remote sensing, sensor technology and control theory. Researchers will face the challenge of integrating plant physiology, soil physics and production sciences and solving the supply chain coordination problem (SCCP).

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