Temporal and spatial patterns of spawning in jack mackerel, Trachurus declivis (Pisces:Carangidae), during 1988-91 in eastern Tasmanian waters

1995 ◽  
Vol 46 (5) ◽  
pp. 831 ◽  
Author(s):  
A Jordan ◽  
G Pullen ◽  
J Marshall ◽  
H Williams
Keyword(s):  
Thermal Structure ◽  
Shelf Break ◽  
Eastern Coast ◽  
Jack Mackerel ◽  
Spatial And Temporal Patterns ◽  
Cold Event ◽  
Temporal And Spatial ◽  
High Concentrations ◽  
Break Region ◽  
Eggs And Larvae

Ichthyoplankton surveys conducted during the summer and autumn of 1988-89, 1989-90 and 1990-91 along the eastern coast of Tasmania were used to examine the spatial and temporal patterns of eggs and larvae of jack mackerel, Trachurus declivis. Results indicate that the species spawns along the entire eastern coast during summer. Trachurus declivis eggs were most abundant at shelf-break stations, indicating that spawning is concentrated in this region, although high concentrations of eggs were present on the inner shelf in 1988-89, which can be attributed to rapid onshore transport in that year. Larvae were evenly dispersed over the shelf, with the distribution of larval ages showing no indication of inshore recruitment. Considerable interannual differences in sea surface temperatures and vertical thermal structure were apparent, with the warmer waters and strong thermal stratification in the summer of 1988-89 resulting from the influx of subtropical East Australian Current (EAC) water onto the shelf, which corresponded with a major La Nina 'cold event' at that time. It is suggested that the distribution of spawning is unaffected by the interannual variations in oceanography as the mature population spawns in deeper water in the shelf-break region that is unaffected by the warming in surface waters.

Methanogenesis in freshwater sediments: inherent variability and effects of environmental contaminants

1981 ◽  
Vol 27 (2) ◽  
pp. 198-205 ◽  
Author(s):  
D. Pedersen ◽  
G. S. Sayler
Keyword(s):  
Relative Concentration ◽  
Environmental Contaminants ◽  
Significant Inhibition ◽  
Freshwater Sediments ◽  
Temporal And Spatial Variation ◽  
Temporal And Spatial Variability ◽  
Total Variability ◽  
Temporal And Spatial ◽  
High Concentrations ◽  
Freshwater Reservoir

Temporal and spatial variability of methanogenesis and the effects of environmental contamination on methanogenesis were examined in freshwater sediments. Temporal and spatial variation was found to be significant in uncontaminated freshwater reservoir sediments. The relative concentration of organic matter and temperature explained approximately 43% of the total variability. Known environmental contaminants marginally inhibited methanogenesis and only a coal conversion effluent and phenanthrene, 100 mg L−1, demonstrated statistically significant inhibition of methanogenesis under acute dosing conditions. Methyl viologen, a potent inhibitor of pure culture methanogenesis, inhibited sediment methanogenesis at high concentrations, i.e., 2570 mg L−1, indicating that the sediment environment protected the methanogenic population from the toxic effects of the environmental contaminants.

Net Primary Production in the Shortgrass Steppe

2008 ◽  
Author(s):  
William K. Lauenroth ◽  
Daniel G. Milchunas
Keyword(s):  
Global Change ◽  
Primary Production ◽  
Net Primary Production ◽  
Regional Scale ◽  
Ecosystem Dynamics ◽  
Shortgrass Steppe ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Spatial And Temporal Patterns ◽  
Temporal And Spatial

Net primary production (NPP), the amount of carbon or energy fixed by green plants in excess of their respiratory needs, is the fundamental quantity upon which all heterotrophs and the ecosystem processes they are associated with depend. Understanding NPP is therefore a prerequisite to understanding ecosystem dynamics. Our objectives for this chapter are to describe the current state of our knowledge about the temporal and spatial patterns of NPP in the shortgrass steppe, to evaluate the important variables that control NPP, and to discuss the future of NPP in the shortgrass steppe given current hypotheses about global change. Most of the data available for NPP in the shortgrass steppe are for aboveground net primary production (ANPP), so most of our presentation will focus on ANPP and we will deal with belowground net primary production (BNPP) as a separate topic. Furthermore, our treatment of NPP in this chapter will ignore the effects of herbivory, which will be covered in detail in chapter 16. Our approach will be to start with a regional-scale view of ANPP in shortgrass ecosystems and work toward a site-scale view. We will begin by briefly placing ANPP in the shortgrass steppe in its larger context of the central North American grassland region. We will then describe the regional-scale patterns and controls on ANPP, and then move to the site-scale patterns and controls on ANPP. At the site scale, we will describe both temporal and spatial dynamics, and controls on ANPP as well as BNPP. We will then discuss relationships between spatial and temporal patterns in ANPP and end the chapter with a short, speculative section on how future global change may influence NPP in the shortgrass steppe. Temperate grasslands in central North America are found over a range of mean annual precipitation from 200 to 1200 mm.y–1 and mean annual temperatures from 0 to 20 oC (Lauenroth et al., 1999). The widely cited relationship between mean annual precipitation and average annual ANPP allows us to convert the precipitation gradient into a production gradient (Lauenroth, 1979; Lauenroth et al., 1999; Noy-Meir, 1973; Rutherford, 1980; Sala et al., 1988b).

scholarly journals Spatial and Temporal Wildfire Decomposition as a Tool for Assessment and Planning of an Efficient Forest Policy in Galicia (Spain)

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 811
Author(s):  
Jesús Barreal ◽  
Gil Jannes
Keyword(s):  
Forest Policy ◽  
Spatial Behavior ◽  
Spatial And Temporal Patterns ◽  
Monthly Data ◽  
Forest Policies ◽  
Spatial Trends ◽  
Index Decomposition ◽  
Temporal And Spatial ◽  
Autumn And Winter ◽  
Forest District

Wildfires in Galicia have various temporal and spatial trends. This temporal and spatial behavior must therefore be studied and taken into account in order to design more efficient forest policies. Since both factors are inhomogeneous, it was proposed to study them using a Gini index decomposition. The number of fires and the affected forest area were studied in terms of the months and the forest districts, which serve as basic temporal and spatial elements. The objective of this methodology is to know the months in which the fires are most concentrated throughout the administrative geographical districts of the various provinces of Galicia, and the elasticity of each month with respect to the global concentration. It is also used to know the temporal inequality in each forest district of Galicia and its contribution to the global index. To apply this methodology, monthly data are taken from 2006 to 2015 for each of the Galician forest districts. It is found that there is a high spatial concentration of fires in the autumn and winter months, and a much lower one in the remaining months. On the other hand, most districts register a great temporal inequality in the occurrence of fires. Tentative suggestions of how the forest policy in Galicia could be improved by taking into account both these spatial and temporal patterns are discussed.

CLASSIC MAYA WARFARE AND WEAPONS: Spear, dart, and arrow points of Aguateca and Copan

2005 ◽  
Vol 16 (2) ◽  
pp. 291-304 ◽  
Author(s):  
Kazuo Aoyama
Keyword(s):  
Distribution Patterns ◽  
Classic Maya ◽  
Late Classic ◽  
Temporal And Spatial Distribution ◽  
Maya Civilization ◽  
Temporal And Spatial ◽  
High Concentrations ◽  
Human Conflict ◽  
Copan Valley

To provide some insights into the nature and role of warfare in the rise, development, and decline of Classic Maya civilization, this article discusses spear, dart, and arrow points used by the Classic Maya elites at the rapidly abandoned fortified city of Aguateca, Guatemala, and their temporal and spatial distribution patterns in and around Copan, Honduras. Both the royal family and elite scribes/artists at Aguateca used spear and dart points for intergroup human conflict as well as for artistic and craft production under enemy threat. An important implication is that the ruler and elite scribes/artists were also warriors. The unusually high concentrations of identifiable weaponry at the Early Classic hilltop center of Cerro de las Mesas as well as the Acropolis and other Late Classic locations in the Copan Valley, along with other lines of evidence, indicate that warfare was critical in the development and downfall of Classic Maya civilization at Copan.

Evaluation of emission strength efficacy in simulating black carbon burden with CHIMERE: estimating wintertime radiative effect over Indo-Gangetic Plain

2020 ◽  
Author(s):  
Sanhita Ghosh ◽  
Shubha Verma ◽  
Jayanarayanan Kuttippurath
Keyword(s):  
Black Carbon ◽  
Transport Model ◽  
Indian Subcontinent ◽  
Chemical Transport ◽  
Climate Impacts ◽  
Eastern Coast ◽  
Spatial And Temporal Patterns ◽  
Gangetic Plain ◽  
Bc Aerosols ◽  
Indo Gangetic Plain

<p>Black carbon (BC) aerosols over the Indian subcontinent have been represented inadequately so-far in chemical transport models restricting the accurate assessment of BC-induced climate impacts. The divergence between simulated and measured BC concentration has specifically been reported to be large over the Indo-Gangetic Plain (IGP) during winter when a large BC burden is observed. In this study, we evaluate the BC transport simulations over the IGP in a high resolution (0.1º × 0.1º ) chemical transport model, CHIMERE. We examine the model efficiency to simulate the observed BC distribution executing five sets of simulation experiments: <em>Constrained </em>and<em> bottomup</em> (<em>Smog, Pku, Edgar, Cmip</em>) implementing respectively, the recently estimated India-based constrained BC emission and the latest bottom-up BC emissions (India-based: Smog-India, and global: Coupled Model Intercomparison Project phase 6 (CMIP6), Emission Database for Global Atmospheric Research-V4 (EDGAR-V4) and Peking University BC Inventory (PKU)). The mean BC emission flux over most of the IGP from the five emission datasets is considerably high (450–1000 kg km<sup>-2</sup> y<sup>-1</sup>) with a relatively low divergence obtained for the eastern and upper-mideastern IGP. Evaluation of BC transport simulations shows that the spatial and temporal gradient in the simulated BC concentration from the <em>Constrained </em>was equivalent to that from the <em>bottomup</em> and also to that from observations. This indicates that the spatial and temporal patterns of BC concentration are consistently simulated by the model processes. However, the efficacy to simulate BC distribution is commendable for the estimates from <em>Constrained</em> for which the lowest normalised mean bias (NMB, < 20%) is obtained in comparison to that from the <em>bottomup</em> (37–52%). 75–100% of the observed all-day (daytime) mean BC concentration is simulated most of the times (>80% of the number of stations data) for <em>Constrained</em>, whereas, this being less frequent (<50%) for the <em>Pku, Smog, Edgar</em> and poor for <em>Cmip</em>. The BC-AOD (0.04–0.08) estimated from the <em>Constrained</em> is 20–50% higher than the <em>Pku</em> and <em>Smog</em>. Three main hotspot locations comprising of a large value of BC load are identified over the eastern, mideastern, and northern IGP. Assessment of the effect of BC burden on the wintertime radiative perturbation over the IGP shows that the presence of BC aerosols in the atmosphere enhances atmospheric heating by 2–3 times more compared to that considering atmosphere without BC. Also, a net warming at the top of the atmosphere (TOA) by 10–17 W m<sup>-</sup><sup>2</sup> is noticed from the <em>Constrained</em>, with the largest value estimated in and around megacities (Kolkata and Delhi) that extends to the eastern coast. This value is higher by 10–20% than that from <em>Cmip</em> over the IGP and by 2–10% than that from <em>Smog</em> over Delhi and eastern part of the IGP.</p>

Spatial and temporal groupings of water main pipe breakage in Winnipeg

1988 ◽  
Vol 15 (1) ◽  
pp. 91-97 ◽  
Author(s):  
I. C. Goulter ◽  
A. Kazemi
Keyword(s):  
Water Distribution ◽  
Interval Parameter ◽  
Pipe Failure ◽  
Spatial And Temporal Patterns ◽  
Exponential Decrease ◽  
Spatial Interval ◽  
Ground Conditions ◽  
Temporal And Spatial ◽  
Pipe Breakage ◽  
The City

The spatial and temporal patterns of water distribution pipe failure in the City of Winnipeg are examined. The failures are shown to be strongly clustered in space, where 22% of the total failures examined occur within 1 m of another failure and 46% occur within 20 m of another failure. A strong temporal clustering is also apparent, with 42% of all failures that occur within 1 m of another found also to occur within 1 day of the initial failure in the group. An exponential decrease in the marginal rates of failure with respect to both the temporal and spatial interval parameter is also observed. Earlier failures in a particular location appear to be an important key to assessing potential failures in that vicinity. These results suggest that a fruitful area for further examination for the reduction of failure rates is the change in the ground conditions resulting from an initial leak and its subsequent repair. Key words: failures, groupings, marginal rates, pipes, space, time, water distribution, Winnipeg.

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