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Benthic community patterns reflect water column processes in the Northeast Water polynya (Greenland)
Dieter Piepenburg William G. Ambrose Jr. Angelika Brandt Paul E. Renaud Michael J. Ahrens Preben Jensen 《Journal of Marine Systems》1997,10(1-4)
Benthic community patterns were investigated in the Northeast Water polynya (Greenland) during the summers of 1992 and 1993 to elucidate to what extent the bottom fauna is influenced by the dynamics of the overlying water. Five different fractions of the benthos (foraminiferans, nematodes, polychaetes, peracarid crustaceans, and epibenthic megafauna), ranging in average adult body size over 6 orders of magnitude (from about 100 μm to about 10 cm), were sampled quantitatively at 69 stations in water depths from 40 to 515 m. Total abundances of nematodes, polychaetes and peracarid crustaceans were found to be primarily correlated with parameters characterizing the potential benthic food supply (water column pigment and nitrate concentrations, sediment bound pigments and sediment biological activity), whereas abundances of foraminiferans and megabenthos were largely associated with seabed properties. Four benthic zones were distinguished by separately analyzing the faunistic composition and distribution of the five community fractions for Ob Bank, Western Westwind Trough, Eastern Westwind Trough, and Belgica Trough. This pattern was shown principally to reflect pelagic regimes differing in surface water hydrography, ice cover and euphotic productivity. This is the first time that a synoptic study of several benthic community portions spanning such a range in sizes and life styles has been performed in a polar shelf ecosystem. Our results indicate that abundances as well as composition of Arctic benthos are largely influenced by mesoscale pelagic processes, and thus provide further evidence for the importance of the benthic-pelagic coupling in high latitude seas. 相似文献
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Using hedonic price functions, we study the influence of access to public railway stations on the prices of surrounding condominiums in Hamburg, Germany. The study examines the influence of rail infrastructure on residential property prices, not only of individual lines, but for the entire rail network of a metropolitan region. We test the stability of the coefficients for different sets of control variables. The study also estimates public-transit-induced increases in tax revenues due to real estate price increases for a study area outside the United States. We control for spatial dependence and numerous variables correlated with the proximity of railway stations and show that access to the public transit system of the city of Hamburg is to be rated with price increases of up to 4.6%. Such premiums for higher-income neighbourhoods and for subterranean stations tend to be higher. The premiums calculated are significantly lower than average price premiums reported in previous studies, which were mostly based on much fewer variables that rail access might be correlated to. 相似文献
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Mintesnot G. Woldeamanuel Rita Cyganski Angelika Schulz Andreas Justen 《Transportation》2009,36(4):371-387
For economic and environmental policy formulation and with the effort of creating less car dependent societies, it is important
to study the changing characteristics of car ownership in a household through time as well as factors responsible of these
variations. There is a vast body of literature on empirical studies of car ownership and use. These studies have investigated
the socio-economic background of the decision maker, the built environment and the perception associated with owning a car
as determinant factors of car ownership and use. In most cases, these analyses have been carried out using cross-sectional
data sets. However, the analysis of factors determining changes in travel behavior of an individual or household requires
information on their behavior over time (longitudinal data set). In this study, the German Mobility Panel (1996–2006) is used
to examine variation of car ownership through time and across households. The panel data modeling results showed that there
are variations of car ownership between households whereas changes in car ownership of a given household over time (within
household variations) are insignificant. The influence of other factors such as the households’ socio-economic background,
the availability of public transportation and shopping/leisure facilities, perception on parking difficulties and satisfaction
with existing public transportation services on the car owning characteristics of households is also presented and discussed
in this paper.
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Andreas JustenEmail: |
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