Distance effects on short-term recolonization of Sargassum stenophyllum by mobile epifauna, with an analysis of gammarid life habits

2004 ◽  
Vol 84 (5) ◽  
pp. 901-910 ◽  
Author(s):  
Marcel O. Tanaka ◽  
Fosca P.P. Leite
Keyword(s):  
Small Scale ◽  
Dominant Group ◽  
Short Term ◽  
Free Living ◽  
Representative Species ◽  
Life Habits ◽  
Colonization Patterns ◽  
Faunal Distribution ◽  
Colonization Rates ◽  
Mobile Epifauna

We evaluated experimentally whether distance between patches of the brown alga Sargassum stenophyllum relative to the source of colonizers influenced colonization patterns by (1) mobile epifauna and (2) gammarid amphipods with distinct life habits. Amphipods were the dominant group, commonly dispersing to patches up to 8 m distant from the algal bed, with low densities of other faunal groups. Assemblage structure of both faunal groups and gammarid amphipods on defaunated algae generally converged to that of controls during the experiments in less than eight days. Gammarid amphipods were dominated by tube-dwellers, but free-living nestlers also colonized the available substrate, and both reached control densities during the study. The same pattern was observed for representative species within each group. Colonization rates were related to faunal densities on the algal bed for most groups, suggesting that mobile organisms disperse more to new habitat patches in high density conditions. Thus, species with direct development can rapidly establish new aggregations at favourable sites, and contribute to small-scale heterogeneity in faunal distribution.

Short-term responses of plants and invertebrates to experimental small-scale grassland fragmentation

Oecologia ◽  
2000 ◽  
Vol 125 (4) ◽  
pp. 559-572 ◽  
Author(s):  
Samuel Zschokke ◽  
Claudine Dolt ◽  
Hans-Peter Rusterholz ◽  
Peter Oggier ◽  
Brigitte Braschler ◽  
...  
Keyword(s):  
Small Scale ◽  
Short Term

scholarly journals An On-Line Low-Cost Irradiance Monitoring Network with Sub-Second Sampling Adapted to Small-Scale PV Systems

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3405 ◽  
Author(s):  
Manuel Espinosa-Gavira ◽  
Agustín Agüera-Pérez ◽  
Juan González de la Rosa ◽  
José Palomares-Salas ◽  
José Sierra-Fernández
Keyword(s):  
Sensor Networks ◽  
Low Cost ◽  
Monitoring Network ◽  
Absolute Error ◽  
Small Scale ◽  
Photovoltaic Systems ◽  
Real Time Control ◽  
Short Term ◽  
Time Control ◽  
Cloud Motion

Very short-term solar forecasts are gaining interest for their application on real-time control of photovoltaic systems. These forecasts are intimately related to the cloud motion that produce variations of the irradiance field on scales of seconds and meters, thus particularly impacting in small photovoltaic systems. Very short-term forecast models must be supported by updated information of the local irradiance field, and solar sensor networks are positioning as the more direct way to obtain these data. The development of solar sensor networks adapted to small-scale systems as microgrids is subject to specific requirements: high updating frequency, high density of measurement points and low investment. This paper proposes a wireless sensor network able to provide snapshots of the irradiance field with an updating frequency of 2 Hz. The network comprised 16 motes regularly distributed over an area of 15 m × 15 m (4 motes × 4 motes, minimum intersensor distance of 5 m). The irradiance values were estimated from illuminance measurements acquired by lux-meters in the network motes. The estimated irradiances were validated with measurements of a secondary standard pyranometer obtaining a mean absolute error of 24.4 W/m 2 and a standard deviation of 36.1 W/m 2 . The network was able to capture the cloud motion and the main features of the irradiance field even with the reduced dimensions of the monitoring area. These results and the low-cost of the measurement devices indicate that this concept of solar sensor networks would be appropriate not only for photovoltaic plants in the range of MW, but also for smaller systems such as the ones installed in microgrids.

scholarly journals Short-term post-mortality scavenging and longer term recovery after anoxia in the northern Adriatic Sea

2013 ◽  
Vol 10 (11) ◽  
pp. 7647-7659 ◽  
Author(s):  
M. Blasnig ◽  
B. Riedel ◽  
L. Schiemer ◽  
M. Zuschin ◽  
M. Stachowitsch
Keyword(s):  
Adriatic Sea ◽  
Time Lapse ◽  
Hermit Crabs ◽  
Small Scale ◽  
Short Term ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Hexaplex Trunculus ◽  
Distinct Sequence ◽  
And Function

Abstract. The northern Adriatic Sea is one of nearly 500 areas worldwide suffering widespread mortalities due to anoxia. The present study documents post-anoxia macrofauna dynamics after experimentally inducing small-scale anoxia in 24 m depth (2 plots, each 50 cm × 50 cm). Time-lapse camera deployments examined short-term scavenging of the moribund and dead organisms (multi-species clumps consisting of sponges and ascidians) over two 3-day periods (August 2009: 71.5 h, September 2009: 67.5 h). Longer term recovery (days to 2 yr) in the same two plots was examined with an independent photo series. Scavengers arrived quickly and in a distinct sequence: demersal (Gobius niger, Serranus hepatus) and benthopelagic fishes (Diplodus vulgaris, Pagellus erythrinus), followed by hermit crabs (Paguristes eremita, showing a clear day/night rhythm in presence) and gastropods (Hexaplex trunculus). This sequence is attributed to the relative speeds and densities of the organisms. The sessile fauna was largely removed or consumed within seven (August plot) and 13 (September plot) days after anoxia, confirming our first hypothesis that decaying organisms are quickly utilised. The scavengers remained in dense aggregations (e.g. up to 33 P. eremita individuals at one time) as long as dead organisms were available. No recovery of sessile macroepibenthos macroepibenthos occurred in the experimental plots one and two years after anoxia, undermining our second hypothesis that small denuded areas are more rapidly recolonised. This study underlines the sensitivity of this soft-bottom community and supports calls for reducing additional anthropogenic disturbances such as fishing practices that further impede recolonisation and threaten benthic community structure and function over the long term.

scholarly journals How big is the influence of biogenic silicon pools on short-term changes in water-soluble silicon in soils? Implications from a study of a 10-year-old soil–plant system

2017 ◽  
Vol 14 (22) ◽  
pp. 5239-5252 ◽  
Author(s):  
Daniel Puppe ◽  
Axel Höhn ◽  
Danuta Kaczorek ◽  
Manfred Wanner ◽  
Marc Wehrhan ◽  
...  
Keyword(s):  
Water Soluble ◽  
Small Scale ◽  
Testate Amoeba ◽  
Short Term ◽  
Plant Materials ◽  
Main Driver ◽  
Key Factor ◽  
Calamagrostis Epigejos ◽  
Biogenic Silicon ◽  
Future Work

Abstract. The significance of biogenic silicon (BSi) pools as a key factor for the control of Si fluxes from terrestrial to aquatic ecosystems has been recognized for decades. However, while most research has been focused on phytogenic Si pools, knowledge of other BSi pools is still limited. We hypothesized that different BSi pools influence short-term changes in the water-soluble Si fraction in soils to different extents. To test our hypothesis we took plant (Calamagrostis epigejos, Phragmites australis) and soil samples in an artificial catchment in a post-mining landscape in the state of Brandenburg, Germany. We quantified phytogenic (phytoliths), protistic (diatom frustules and testate amoeba shells) and zoogenic (sponge spicules) Si pools as well as Tiron-extractable and water-soluble Si fractions in soils at the beginning (t0) and after 10 years (t10) of ecosystem development. As expected the results of Tiron extraction showed that there are no consistent changes in the amorphous Si pool at Chicken Creek (Hühnerwasser) as early as after 10 years. In contrast to t0 we found increased water-soluble Si and BSi pools at t10; thus we concluded that BSi pools are the main driver of short-term changes in water-soluble Si. However, because total BSi represents only small proportions of water-soluble Si at t0 (< 2 %) and t10 (2.8–4.3 %) we further concluded that smaller (< 5 µm) and/or fragile phytogenic Si structures have the biggest impact on short-term changes in water-soluble Si. In this context, extracted phytoliths (> 5 µm) only amounted to about 16 % of total Si contents of plant materials of C. epigejos and P. australis at t10; thus about 84 % of small-scale and/or fragile phytogenic Si is not quantified by the used phytolith extraction method. Analyses of small-scale and fragile phytogenic Si structures are urgently needed in future work as they seem to represent the biggest and most reactive Si pool in soils. Thus they are the most important drivers of Si cycling in terrestrial biogeosystems.

scholarly journals The Unbearable Lightness of Trust: Trade, conviviality, and the life-world of Indian export agents in Yiwu, China

2021 ◽  
pp. 1-31
Author(s):  
Filippo Osella
Keyword(s):  
United Arab Emirates ◽  
Small Scale ◽  
Export Trade ◽  
Short Term ◽  
Economic Interests ◽  
Life World ◽  
Extreme Caution ◽  
The World ◽  
Ethnographic Data ◽  
World Centre

Abstract Drawing on ethnographic data collected in China, the United Arab Emirates (UAE), and India, this article explores the life-world and practices of small-scale Indian export agents based in Yiwu, China, the world centre for the export of small commodities. It shows that in a market overdetermined by fast-moving goods, short-term gains, and low margins, export agents have to steer their way between acting with extreme caution or taking risks with their clients and suppliers. These apparently contradictory dispositions or orientations are negotiated by the judicious exercise of mistrust and suspicion. The article suggests not only that mistrust is valued and cultivated as an indispensable practical resource for success in Yiwu's export trade, but that contingent relations of trust between market players emerge at the interstices of a generalized mutual mistrust, via the mobilization of practices of hospitality, commensality, and masculine conviviality. Indeed, feelings of amity and mutuality elicited by the performance of modalities of social intimacy become the affective terrain upon which divergent economic interests might be reconciled and taken forward. That is, mistrust might not lead to generalized distrust, instead a situational or contingent trust might actually emerge through the judicious exercise of mistrust.

scholarly journals Supporting Spatial Management of Data-Poor, Small-Scale Fisheries With a Bayesian Approach

2021 ◽  
Vol 8 ◽  
Author(s):  
Jennifer Rehren ◽  
Maria Grazia Pennino ◽  
Marta Coll ◽  
Narriman Jiddawi ◽  
Christopher Muhando
Keyword(s):  
Spatial Distribution ◽  
Marine Conservation ◽  
Environmental Drivers ◽  
Small Scale ◽  
Target Species ◽  
Short Term ◽  
Conservation Areas ◽  
Bayesian Hierarchical ◽  
Small Scale Fisheries ◽  
Spatial Management

Marine conservation areas are an important tool for the sustainable management of multispecies, small-scale fisheries. Effective spatial management requires a proper understanding of the spatial distribution of target species and the identification of its environmental drivers. Small-scale fisheries, however, often face scarcity and low-quality of data. In these situations, approaches for the prioritization of conservation areas need to deal with scattered, biased, and short-term information and ideally should quantify data- and model-specific uncertainties for a better understanding of the risks related to management interventions. We used a Bayesian hierarchical species distribution modeling approach on annual landing data of the heavily exploited, small-scale, and data-poor fishery of Chwaka Bay (Zanzibar) in the Western Indian Ocean to understand the distribution of the key target species and identify potential areas for conservation. Few commonalities were found in the set of important habitat and environmental drivers among species, but temperature, depth, and seagrass cover affected the spatial distribution of three of the six analyzed species. A comparison of our results with information from ecological studies suggests that our approach predicts the distribution of the analyzed species reasonably well. Furthermore, the two main common areas of high relative abundance identified in our study have been previously suggested by the local fisher as important areas for spatial conservation. By using short-term, catch per unit of effort data in a Bayesian hierarchical framework, we quantify the associated uncertainties while accounting for spatial dependencies. More importantly, the use of accessible and interpretable tools, such as the here created spatial maps, can frame a better understanding of spatio-temporal management for local fishers. Our approach, thus, supports the operability of spatial management in small-scale fisheries suffering from a general lack of long-term fisheries information and fisheries independent data.

scholarly journals Effects of agricultural credit on wheat productivity of small farms in Sindh, Pakistan

2018 ◽  
Vol 78 (5) ◽  
pp. 592-610 ◽  
Author(s):  
Abbas Ali Chandio ◽  
Yuansheng Jiang ◽  
Feng Wei ◽  
Xu Guangshun
Keyword(s):  
Wheat Yield ◽  
Considerable Proportion ◽  
Small Scale ◽  
Small Farms ◽  
Short Term ◽  
Agricultural Credit ◽  
Data Set ◽  
Content Type ◽  
The Impact

Purpose The purpose of this paper is to evaluate the impact of short-term loan (STL) vs long-term loan (LTL) on wheat productivity of small farms in Sindh, Pakistan. Design/methodology/approach The econometric estimation is based on cross-sectional data collected in 2016 from 18 villages in three districts, i.e. Shikarpur, Sukkur and Shaheed Benazirabad, Sindh, Pakistan. The sample data set consist of 180 wheat farmers. The collected data were analyzed through different econometric techniques like Cobb–Douglas production function and Instrumental variables (two-stage least squares) approach. Findings This study reconfirmed that agricultural credit has a positive and highly significant effect on wheat productivity, while the short-term loan has a stronger effect on wheat productivity than the long-term loan. The reasons behind the phenomenon may be the significantly higher usage of agricultural inputs like seeds of improved variety and fertilizers which can be transformed into the wheat yield in the same year. However, the LTL users have significantly higher investments in land preparation, irrigation and plant protection, which may lead to higher wheat production in the coming years. Research limitations/implications In the present study, only those wheat farmers were considered who obtained agricultural loans from formal financial institutions like Zarai Taraqiati Bank Limited and Khushhali Bank. However, in the rural areas of Sindh, Pakistan, a considerable proportion of small-scale farmers take credit from informal financial channels. Therefore future researchers should consider the informal credits as well. Originality/value This is the first paper to examine the effects of agricultural credit on wheat productivity of small farms in Sindh, Pakistan. This paper will be an important addition to the emerging literature regarding effects of credit studies.

Short-term and long-term variability of indices related to nutritional status. I: Ca, Cu, Fe, Mg, and Zn.

1989 ◽  
Vol 35 (3) ◽  
pp. 369-373 ◽  
Author(s):  
S K Gallagher ◽  
L K Johnson ◽  
D B Milne
Keyword(s):  
Superoxide Dismutase ◽  
Nutritional Status ◽  
Iron Status ◽  
Short Term ◽  
Free Living ◽  
Analytical Technique ◽  
Metabolic Unit ◽  
Biological Component ◽  
Analytical Variation

Abstract Five free-living women (ages 28-38 y) and five women (ages 23-44 y) residing in a metabolic unit and eating a constant diet were assessed for variation in indices related to mineral nutrition. Blood was sampled once a month for five months, once a week for five weeks, and once a day for five days to assess analytical and biological variability. Analytical variability was determined by using concurrently run duplicate control samples prepared from plasma or serum pools. Of the measured indices, serum ferritin varied most, with intra-individual variance of 4.72% to 18.0%. Much of this variance may have been because of changes in iron status or in the analytical technique used. Intra-individual month-to-month variance for other indices ranged from 17% for superoxide dismutase (EC 1.15.1.1) to 1.5% for calcium. Correction for long-term analytical variation indicated that most of the variance was associated with the biological component. The higher biological variabilities of some indices, including ferritin or superoxide dismutase, need to be considered when nutritional status is being evaluated or when serial observations are made over a protracted period in clinical studies or trials.

scholarly journals Short-term, but not long-term, increased daytime workload leads to decreased night-time energetics in a free-living song bird

2019 ◽  
Vol 222 (14) ◽  
pp. jeb199513 ◽  
Author(s):  
Marcel E. Visser ◽  
Coby van Dooremalen ◽  
Barbara M. Tomotani ◽  
Andrey Bushuev ◽  
Harro A. J. Meijer ◽  
...  
Keyword(s):  
Short Term ◽  
Night Time ◽  
Free Living ◽  
Song Bird

Spatial aggregation patterns of free-living marine nematodes in contrasting sandy beach micro-habitats

2010 ◽  
Vol 91 (3) ◽  
pp. 615-622 ◽  
Author(s):  
Ruth Gingold ◽  
Silvia E. Ibarra-Obando ◽  
Axayácatl Rocha-Olivares
Keyword(s):  
Negative Correlation ◽  
Sandy Beach ◽  
Distribution Patterns ◽  
Significant Negative Correlation ◽  
Small Scale ◽  
Spatial Distributions ◽  
Biological Processes ◽  
Marine Nematodes ◽  
Free Living ◽  
Biological Similarity

In the absence of chemical or physical gradients, random displacement of organisms can result in unpredictable distribution patterns. In spite of a limited locomotive capability, marine nematodes may choose where to settle after re-suspension and may maintain their position in the sediment under calm conditions, leading to small-scale (<1 m) spatial variability. However, in more energetic environments, nematodes become re-suspended with sediments and re-distributed at distances dependent on prevalent hydrodynamic regimes, from metre- to decametre-scale or more. In this study, we tested the hypothesis that micro-habitats (i.e. runnels and sandbars) in a macrotidal sandy beach influence the distribution patterns of free-living marine nematodes by exhibiting contrasting hydrodynamic regimes. Specifically, we predicted patchier distributions in the calmer environment (runnel). We sampled nematodes in each habitat from <1 m to decametre scales. Our results show more heterogeneous spatial distributions in the runnel, presumably owing to a predominance of active displacement under calmer conditions and sediment cohesion by algal films. Biological similarity among runnel replicates was low, whereas replicates from the sandbar exhibited higher similarity, presumably because of homogenization of the sediment and inhabiting fauna by tidal currents. A significant negative correlation between biological similarity and sampling distance was found in the runnel, but not in the sandbar. The most similar samples were the closest in the runnel and the most distant in the sandbar. More patchily distributed taxa were found in the runnel and a larger fraction of homogeneously or randomly distributed taxa in the sandbar. We conclude that different hydrodynamic regimes in contrasting intertidal micro-habitats significantly influenced the nematofaunal distribution, resulting in different spatial patterns next to one another in the same beach. This has significant implications for sampling and monitoring designs and begs the need for detailed studies about the physical and biological processes governing meiobenthic communities.

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