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Robert J W Brewin - One of the best experts on this subject based on the ideXlab platform.
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Phytoplankton Size Structure in Association with Mesoscale Eddies off Central-Southern Chile: The Satellite Application of a Phytoplankton Size-Class Model
MDPI AG, 2018Co-Authors: Andrea Corredor-acosta, Robert J W Brewin, Carmen E. Morales, Pierre-amaël Auger, Oscar Pizarro, Samuel Hormazabal, Valeria AnabalónAbstract:Understanding the influence of mesoscale and submesoscale features on the Structure of phytoplankton is a key aspect in the assessment of their influence on marine biogeochemical cycling and cross-shore exchanges of plankton in Eastern Boundary Current Systems (EBCS). In this study, the spatio-temporal evolution of phytoplankton Size classes (PSC) in surface waters associated with mesoscale eddies in the EBCS off central-southern Chile was analyzed. Chlorophyll-a (Chl-a) Size-fractionated filtration (SFF) data from in situ samplings in coastal and coastal transition waters were used to tune a three-component (micro-, nano-, and pico-phytoplankton) model, which was then applied to total Chl-a satellite data (ESA OC-CCI product) in order to retrieve the Chl-a concentration of each PSC. A sea surface, height-based eddy-tracking algorithm was used to identify and track one cyclonic (sC) and three anticyclonic (ssAC1, ssAC2, sAC) mesoscale eddies between January 2014 and October 2015. Satellite estimates of PSC and in situ SFF Chl-a data were highly correlated (0.64 < r < 0.87), although uncertainty values for the microplankton fraction were moderate to high (50 to 100% depending on the metric used). The largest changes in Size Structure took place during the early life of eddies (~2 months), and no major differences in PSC between eddy center and periphery were found. The contribution of the microplankton fraction was ~50% (~30%) in sC and ssAC1 (ssAC2 and sAC) eddies when they were located close to the coast, while nanoplankton was dominant (~60–70%) and picoplankton almost constant (<20%) throughout the lifetime of eddies. These results suggest that the three-component model, which has been mostly applied in oceanic waters, is also applicable to highly productive coastal upwelling systems. Additionally, the PSC changes within mesoscale eddies obtained by this satellite approach are in agreement with results on phytoplankton Size distribution in mesoscale and submesoscale features in this region, and are most likely triggered by variations in nutrient concentrations and/or ratios during the eddies’ lifetimes
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the influence of the indian ocean dipole on interannual variations in phytoplankton Size Structure as revealed by earth observation
Deep-sea Research Part Ii-topical Studies in Oceanography, 2012Co-Authors: Robert J W Brewin, Takafumi Hirata, N J Hardmanmountford, Samantha Lavender, Shubha Sathyendranath, R BarlowAbstract:Abstract Using a decade of satellite ocean-colour observations and a model that links chlorophyll-a to the Size of the phytoplankton cells, parameterised using pigment data from the Indian Ocean, we examine the implications of the Indian Ocean Dipole (IOD) for phytoplankton Size Structure. The inferred interannual anomalies in phytoplankton Size Structure are related to those in sea-surface temperature (SST) and sea-surface height (SSH), derived using satellite radiometry and altimetry, and stratification, derived using the Simple Ocean Data Assimilation (SODA) database. In regions influenced by the Indian Ocean Dipole, we observe a tight correlation between phytoplankton Size Structure and the physical variables, such that interannual variations in the physical variables accounts for up to 70% of the total variance in phytoplankton Size Structure. For much of the Indian Ocean, low temperature, low SSH and low stratification (indicative of a turbulent environment) are correlated with larger Size classes, consistent with theories on coupling between physical–chemical processes and ecosystem Structure. To the extent that phytoplankton function is related to its Size Structure, changes in physical forcing are likely to influence biogeochemical cycles in the region and the pelagic food web. The limitations of our approach are discussed and we highlight future challenges in satellite ocean-colour monitoring, should climate change lead to any modification in our marine ecosystem.
R Barlow - One of the best experts on this subject based on the ideXlab platform.
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the influence of the indian ocean dipole on interannual variations in phytoplankton Size Structure as revealed by earth observation
Deep-sea Research Part Ii-topical Studies in Oceanography, 2012Co-Authors: Robert J W Brewin, Takafumi Hirata, N J Hardmanmountford, Samantha Lavender, Shubha Sathyendranath, R BarlowAbstract:Abstract Using a decade of satellite ocean-colour observations and a model that links chlorophyll-a to the Size of the phytoplankton cells, parameterised using pigment data from the Indian Ocean, we examine the implications of the Indian Ocean Dipole (IOD) for phytoplankton Size Structure. The inferred interannual anomalies in phytoplankton Size Structure are related to those in sea-surface temperature (SST) and sea-surface height (SSH), derived using satellite radiometry and altimetry, and stratification, derived using the Simple Ocean Data Assimilation (SODA) database. In regions influenced by the Indian Ocean Dipole, we observe a tight correlation between phytoplankton Size Structure and the physical variables, such that interannual variations in the physical variables accounts for up to 70% of the total variance in phytoplankton Size Structure. For much of the Indian Ocean, low temperature, low SSH and low stratification (indicative of a turbulent environment) are correlated with larger Size classes, consistent with theories on coupling between physical–chemical processes and ecosystem Structure. To the extent that phytoplankton function is related to its Size Structure, changes in physical forcing are likely to influence biogeochemical cycles in the region and the pelagic food web. The limitations of our approach are discussed and we highlight future challenges in satellite ocean-colour monitoring, should climate change lead to any modification in our marine ecosystem.
Wenzhao Liang - One of the best experts on this subject based on the ideXlab platform.
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phytoplankton Size Structure in the western south china sea under the influence of a jet eddy system
Journal of Marine Systems, 2018Co-Authors: Wenzhao Liang, Danling Tang, Xin LuoAbstract:Abstract A northeastward jet in the western South China Sea (SCS) usually induces phytoplankton blooms during summertime. This jet is often sandwiched by a cyclonic eddy in the north and an anticyclonic eddy in the south. Using in situ and satellite data, the present study analyzes the combined impact of the northeastward jet and two eddies on the phytoplankton Size Structure (PSS) from August to September 2014. Generally, picophytoplankton is the major Size fraction in surface water, contributing 73% of the total chlorophyll a concentration. The data showed that a high chlorophyll a belt (av. 0.29 ± 0.18 μg L−1) with a large percentage of microphytoplankton (av. 14%) appeared in the northeastward jet. Meanwhile, similar chlorophyll a concentrations were observed in the cyclonic (av. 0.072 ± 0.019 μg L−1) and anticyclonic eddies (av. 0.087 ± 0.02 μg L−1), but microphytoplankton contributed 6.7% more in the anticyclonic eddy. Below the surface, however, the dominant Size of phytoplankton switched from pico to nano and micro with increasing depth. In contrast to the observations at the surface, the jet and anticyclonic eddy presented a lower microphytoplankton contribution than the cyclonic eddy. Horizontally, advection of coastal upwelling water by the northeastward jet enhanced the growth of phytoplankton and influenced the surface PSS. Meanwhile, divergence/convergence in cyclonic/anticyclonic eddy interaction with the northeastward jet formed the high chlorophyll a belt at the edge of the eddy and increased the microphytoplankton contribution through water mass transport and mixing. Nutrient supply and weakening of the light intensity below the surface layer synergistically influenced the concentration and Size Structure of phytoplankton in the cyclonic/anticyclonic eddies at different depths. Finally, this study proposed a ‘jet-eddy system’ to explain summer spatial characteristics of PSS in the western SCS. Source water (riverine and coastal upwelling water) that feeds the ‘jet-eddy system’ is another key factor affecting phytoplankton biomass and its Size Structure.
Allen N Berger - One of the best experts on this subject based on the ideXlab platform.
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does market Size Structure affect competition the case of small business lending
Journal of Banking and Finance, 2007Co-Authors: Allen N Berger, Richard J Rosen, Gregory F UdellAbstract:Abstract Market Size Structure refers to the distribution of shares of different Size classes of local market participants, where the Sizes are inclusive of assets both within and outside the local market. We apply this new measure of market Structure in two empirical analyses of the US banking industry to address concerns regarding the effects of the consolidation in banking. Our quantity analysis of the likelihood that small businesses borrow from large versus small banks and our small business loan price analysis that includes market Size Structure as well as conventional measures yield very different findings from most of the literature on bank Size and small business lending. Our results do not suggest a significant net advantage or disadvantage for large banks in small business lending overall, or in lending to informationally opaque small businesses in particular. We argue that the prior research that excluded market Size Structure may be misleading and offer some likely explanations of why our results differ.
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the effect of market Size Structure on competition the case of small business lending
2001Co-Authors: Allen N Berger, Richard J Rosen, Gregory F UdellAbstract:Banking industry consolidation has raised concern about the supply of small business credit since large banks generally invest lower proportions of their assets in small business loans. However, we find that the likelihood that a small business borrows from a bank of a given Size is roughly proportional to the local market presence of banks of that Size, although there are exceptions. Moreover, small business loan interest rates depend more on the Size Structure of the market than on the Size of the bank providing the credit, with markets dominated by large banks generally charging lower prices.
I. Maguire - One of the best experts on this subject based on the ideXlab platform.
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Size Structure, maturity Size, growth and condition index of stone crayfish (
EDP Sciences, 2011Co-Authors: I. Maguire, G. KlobučarAbstract:Austropotamobius torrentium (Schrank, 1803), the smallest species of freshwater crayfish from the family Astacidae, is considered a vulnerable species, protected by international laws. Since it has never been economically important, it has not been frequently studied. Therefore, the results presented in this paper are a contribution to the knowledge on stone crayfish’s population Size Structure, Size at maturity, growth, and condition index throughout the year, as a possible tool for evaluating protection and restocking measures of this threatened species. The research included three stone crayfish populations with 1492 specimens in the “Medvednica” Nature Park, north-west Croatia, during a period of 18 months. In all the populations studied, crayfish of a total length between 5 and 8 cm prevailed. Activity of different Size classes had a seasonal pattern that could be connected to different crayfish activities throughout the year. Appearance of sexual maturity within the populations coincides with the crayfish total length between 5 and 6 cm, after which allometric growth of males’ claws was recorded. On average males gain 0.42–0.72 cm and 2.65–4.30 g per moult, while females gain 0.44–0.70 cm and 2.04–3.83 g. Crayfish condition varied throughout the year with, in general, both juvenile and adult males having higher condition indices than juvenile and adult females in all three populations. In addition, adult crayfish were in significantly better condition in the autumn, whereas juveniles had higher condition indices in the summer
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Size Structure, maturity Size, growth and condition index of stone crayfish (Austropotamobius torrentium) in North-West Croatia
2011Co-Authors: I. MaguireAbstract:Key-words: stone crayfish, growth, maturity Size, condition index, Croatia Austropotamobius torrentium (Schrank, 1803), the smallest species of freshwater crayfish from the family Astacidae, is considered a vulnera-ble species, protected by international laws. Since it has never been eco-nomically important, it has not been frequently studied. Therefore, the results presented in this paper are a contribution to the knowledge on stone crayfish’s population Size Structure, Size at maturity, growth, and condition index throughout the year, as a possible tool for evaluating protection and restocking measures of this threatened species. The re
