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Anthropogenic factors and habitat complexity influence biodiversity but wave exposure drives species turnover of a subtropical rocky inter‐tidal metacommunity 
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下载免费PDF全文 Coastal ecosystems are complex and species rich, but are vulnerable to degradation from a variety of anthropogenic activities. Nevertheless, information on inter‐tidal community composition in the Caribbean Basin and at other oceanic sites is lacking. Such information is essential to developing a more comprehensive understanding of rocky inter‐tidal systems and their responses to global change. The goals of this study were to determine the relative importance of environmental (wave power density, wave height), habitat (e.g. algal cover, slope, complexity of rock surfaces) and anthropogenic (distance to roads, population density) factors associated with the structure of local assemblages at multiple shore heights and the regional metacommunity of mobile invertebrates on oceanic rocky inter‐tidal habitats. Environmental characteristics associated with habitat complexity (algal cover, rock surface complexity) and human population density were most strongly associated with abundance and biodiversity of invertebrates. Species richness was positively correlated with surface complexity, but abundance was negatively correlated with both surface complexity and per cent algal cover. By contrast, abundance of invertebrates was positively correlated with human population density, and diversity was negatively correlated with human population density. Abundance of invertebrates was greatest in the mid inter‐tidal zone, whereas diversity was greatest in the lower inter‐tidal zone. Metacommunity structure was Gleasonian, but the gradient along which species turnover occurred was correlated with measures of wave exposure, rather than anthropogenic activity. Unlike in previous studies, mostly at mainland sites, human activity primarily altered dominance patterns of communities, while having relatively little effect on species richness or composition. 相似文献
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H. Htún M.R. Payne G. Beaugrand P.C. Reid A.B. Sand H. Drange B. Hansen J.A. Jacobsen D. Bloch 《Progress in Oceanography》2009,80(3-4):149-162
Pronounced changes in fauna, extending from the English Channel in the south to the Barents Sea in the north-east and off Greenland in the north-west, have occurred in the late 1920s, the late 1960s and again in the late 1990s. We attribute these events to exchanges of subarctic and subtropical water masses in the north-eastern North Atlantic Ocean, associated with changes in the strength and extent of the subpolar gyre. These exchanges lead to variations in the influence exerted by the subarctic or Lusitanian biomes on the intermediate faunistic zone in the north-eastern Atlantic. This strong and persistent bottom-up bio-physical link is demonstrated using a numerical ocean general circulation model and data on four trophically connected levels in the food chain – phytoplankton, zooplankton, blue whiting, and pilot whales. The plankton data give a unique basin-scale depiction of these changes, and a long pilot whale record from the Faroe Islands offers an exceptional temporal perspective over three centuries. Recent advances in simulating the dynamics of the subpolar gyre suggests a potential for predicting the distribution of the main faunistic zones in the north-eastern Atlantic a few years into the future, which might facilitate a more rational management of the commercially important fisheries in this region. 相似文献
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A humic acid extracted from a peat was easily hydrolysed by 6N HCl after oxidation with peracetic acid. The proportion of amino-acids in the hydrolysate was high (11,7 g of aminoacids per 100 g of humic acid), when the proportion of NH3 was relatively low. 17 aminoacids were identified and titrated. On the opposite, a humic acid with the same origin, which was not oxidised with peracetic acid, gave less amino-acids on hydrolysis, but tenfold more NH3, which is probably produced by partial decomposition of the amino-acids. 相似文献
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Grzegorz Karasiński Michał Posyniak Magdalena Bloch Piotr Sobolewski Łukasz Małarzewski Jakub Soroka 《Acta Geophysica》2014,62(2):316-339
Two significant volcanic eruptions, i.e., Eyjafjallajökull (April–May 2010) and Grímsvötn (May 2011) took place recently in Iceland. Within a few days after eruptions, layers of high aerosol concentration have been observed by multiwavelength lidar of the Polish Polar Station at Hornsund, Svalbard. Measurements of the aerosol’s optical properties indicated a possible presence of volcanic ash transported over the Station. The latter presumption was confirmed by the computed backward trajectories of air masses, showing their paths passing over the location of volcanoes. 相似文献
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Results of mercury and organochlorine analyses in pooled muscle and blubber samples representing in all 417 long-finned pilot whales (Globicephala melas) sampled in 1997 in the Faroe Islands are presented. The 28 pooled muscle samples from (in all) 9 pods were analysed for total mercury and the same number of pooled blubber samples were analysed for PCB (IUPAC CBs no. 28, 52, 99, 101, 105, 118, 128, 138, 153, 170, 180, 183 and 187), p,p′-DDT and metabolites and o,p′-DDT and metabolites, cis () and trans (γ)-chlordane, cis- and trans-nonachlor, oxychlordane, mirex, hexachlorobenzene, β-HCH and toxaphene (Parlars no. 26 (T2), 32, 50 (T12), 62 (T20) and 69. 相似文献
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Jared M. Maruskin Daniel J. Scheeres Fred C. Adams Anthony M. Bloch 《Celestial Mechanics and Dynamical Astronomy》2008,100(1):43-62
The rosette-shaped motion of a particle in a central force field is known to be classically solvable by quadratures. We present
a new approach of describing and characterizing such motion based on the eccentricity vector of the two body problem. In general,
this vector is not an integral of motion. However, the orbital motion, when viewed from the nonuniformly rotating frame defined
by the orientation of the eccentricity vector, can be solved analytically and will either be a closed periodic circulation
or libration. The motion with respect to inertial space is then given by integrating the argument of periapsis with respect
to time. Finally we will apply the decomposition to a modern central potential, the spherical Hernquist–Newton potential,
which models dark matter halos of galaxies with central black holes. 相似文献
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Since October 2009, a ground-based Raman lidar system has been deployed to perform a regular, night-time, vertical sounding of a water vapour content in the lower and middle troposphere above Polish Polar Station at Hornsund (77.00°N, 15.55°E, 10 m a.s.l.) in the Arctic. The water vapour mixing ratio profiles were obtained for the atmosphere up to 6 km altitude, based on analysis of inelastic Raman backscattering signals from nitrogen molecules (at 387 nm) and water vapour particles (at 407 nm), calibrated with the data from a local Vaisala’s automatic meteorological station. The results obtained for winter seasons in the years 2009–2012 are in a good general agreement with the results obtained from the atmospheric infrared sounder (AIRS) on the Aqua satellite. 相似文献
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Dr. M. R. Bloch 《International Journal of Earth Sciences》1964,54(1):515-522
The eustatic changes of the ocean in prehistoric and historic times are linked with the fate of the ocean based salt industry, and recognized as erratic. A hypothesis is proposed to explain these erratic changes with albedo changes of the polar ice caps, caused in turn by erratic volcanic dust fallout. Ash layers in Antarctic ice cores are connected with historic dislocations of maritime civilizations.Albedo changes through the dusting of the ice caps are proposed to be the cause for the decline of glaciation periods generally. Such albedo changes are connected with volcanic activity on the one hand, and loess formation on the other, caused in turn by the growth of the ice caps. 相似文献
9.
To evaluate climate and atmospheric deposition induced physical and water chemical changes and their effects on phytoplankton
communities, we used complete time series (14 years, monthly measurements during the growing season) of 18 physical and chemical
variables and phytoplankton data from 13 nutrient-poor Swedish reference lakes along a latitudinal gradient. We found numerous
strong significant changes over time that were most coherent among lakes for sulfate concentrations, conductivity, calcium,
magnesium, chloride, potassium, water color, surface water temperature and the intensity of thermal stratification. Despite
these pronounced coherent physical and water chemical changes over Sweden, the phytoplankton biomass and species richness
of six phytoplankton groups, measured at the same time as the water chemical variables, showed only few and weak significant
changes over time. The only coherent significant change over Sweden, occurring in seven lakes, was observed in the species
richness of chlorophytes. The number of chlorophyte taxa significantly declined over Sweden. Using a partial least square
model for each lake, we attributed the decline primarily to an increase in water temperatures and water color, which were
among the most important variables for the model performance of each lake. All other taxonomic groups were driven primarily
by non-coherent changes in nutrient concentrations, pH and probably also non-coherent grazing pressure. We concluded that
coherent phytoplankton responses can only be achieved for taxonomic groups that are driven primarily by coherent physical/chemical
changes. According to our study, chlorophytes belong to such a group, making them possible global change indicators. Our findings
give new insights into global change effects on different phytoplankton taxonomic groups in nutrient-poor lakes. 相似文献
10.
Salman Bloch 《Geochimica et cosmochimica acta》1980,44(2):373-377
Low-temperature alteration of the oceanic crust is a major sink for the U supplied to the oceans and may account for about 50% of the estimated present-day input of this element. Uranium uptake by organic-rich sediments and coexisting phosphorites on continental margins is also important and may remove in excess of 10% of the total supply. High-temperature alteration of oceanic basalts, metalliferous sediments, carbonate sediments, and sediments in anoxic basins deeper than 200 m play a relatively minor role in the removal of U. Each of these sinks is responsible for the uptake of less than 5% of the overall input. 相似文献
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