Potential impact of climate change on ecosystems of the Barents Sea Region     

Hedwig Roderfeld  Eleanor Blyth  Rutger Dankers  Geir Huse  Dag Slagstad  Ingrid Ellingsen  Annett Wolf  Manfred A. Lange 《Climatic change》2008,87(1-2):283-303

The EU project BALANCE (Global Change Vulnerabilities in the Barents region: Linking Arctic Natural Resources, Climate Change and Economies) aims to assess vulnerability to climate change in the Barents Sea Region. As a prerequisite the potential impact of climate change on selected ecosystems of the study area has to be quantified, which is the subject of the present paper. A set of ecosystem models was run to generate baseline and future scenarios for 1990, 2020, 2050 and 2080. The models are based on data from the Regional Climate Model (REMO), driven by a GCM which in turn is forced by the IPCC-B2 scenario. The climate change is documented by means of the Köppen climate classification. Since the multitude of models requires the effect of climate change on individual terrestrial and marine systems to be integrated, the paper concentrates on a standardised visualisation of potential impacts by use of a Geographical Information System for the timeslices 2050 and 2080. The resulting maps show that both terrestrial and marine ecosystems of the Barents region will undergo significant changes until both 2050 and 2080.  相似文献   

Feedback Mechanisms Between Cyanobacterial Blooms,Transient Hypoxia,and Benthic Phosphorus Regeneration in Shallow Coastal Environments     

Mindaugas Zilius  Marco Bartoli  Mariano Bresciani  Marija Katarzyte  Tomas Ruginis  Jolita Petkuviene  Irma Lubiene  Claudia Giardino  Paul A. Bukaveckas  Rutger de Wit  Arturas Razinkovas-Baziukas 《Estuaries and Coasts》2014,37(3):680-694

We investigated the dissolved oxygen metabolism of the Curonian Lagoon (Baltic Sea) to assess the relative contributions of pelagic and benthic processes to the development of transient hypoxic conditions in shallow water habitats. Metabolism measurements along with the remote sensing-derived estimates of spatial variability in chlorophyll a were used to evaluate the risk of hypoxia at the whole lagoon level. Our data demonstrate that cyanobacterial blooms strongly inhibit light penetration, resulting in net heterotrophic conditions in which pelagic oxygen demand exceeds benthic oxygen demand by an order of magnitude. The combination of bloom conditions and reduced vertical mixing during calm periods resulted in oxygen depletion of bottom waters and greater sediment nutrient release. The peak of reactive P regeneration (nearly 30 μmol m^?2 h^?1) coincided with oxygen depletion in the water column, and resulted in a marked drop of the inorganic N:P ratio (from >40 to <5, as molar). Our results suggest a strong link between cyanobacterial blooms, pelagic respiration, hypoxia, and P regeneration, which acts as a feedback in sustaining algal blooms through internal nutrient cycling. Meteorological data and satellite-derived maps of chlorophyll a were used to show that nearly 70 % of the lagoon surface (approximately 1,000 km²) is prone to transient hypoxia development when blooms coincide with low wind speed conditions.  相似文献   

Preface   总被引：1，自引：1，他引：0  

Margareta Wahlström 《Landslides》2015,12(4):629-629

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Seismicity and seismotectonic implications in the southern Baltic Sea area     

Rutger Wahlström  Gottfried Grünthal 《地学学报》1994,6(2):149-157

An updated list of earthquakes and earthquake parameters (location, homogenized magnitude, macroseismic data) for the southern Baltic Sea area reveals activity north of the sea, whereas there are very few epicentres in the sea itself and in the region south of it. This is the first study to combine seismological data for the whole region to cover also the sea. Macroseismic data for the 1930 earthquake were reinvestigated leading to an intensity of V–VI (MM or MSK scale), a radius of perceptibility of 135 km and an unusually big focal depth of about 40 km. It is difficult to correlate individual earthquakes with specific faults, but some seismotectonic relations are suggested, e.g. for the Tornquist zone, the predominant structure of the region. Only few reliable focal-mechanism solutions exist. Possible seismogenic processes (ridge push, isostasy, etc) are discussed.  相似文献   

The European-Mediterranean Earthquake Catalogue (EMEC) for the last millennium   总被引：10，自引：3，他引：7  

Gottfried Grünthal  Rutger Wahlstr?m 《Journal of Seismology》2012,16(3):535-570

The catalogue by Grünthal et al. (J Seismol 13:517?C541, 2009a) of earthquakes in central, northern, and north-western Europe with M _w????3.5 (CENEC) has been expanded to cover also southern Europe and the Mediterranean area. It has also been extended in time (1000?C2006). Due to the strongly increased seismicity in the new area, the threshold for events south of the latitude 44°N has here been set at M _w????4.0, keeping the lower threshold in the northern catalogue part. This part has been updated with data from new and revised national and regional catalogues. The new Euro-Mediterranean Earthquake Catalogue (EMEC) is based on data from some 80 domestic catalogues and data files and over 100 special studies. Available original M _w and M ₀ data have been introduced. The analysis largely followed the lines of the Grünthal et al. (J Seismol 13:517?C541, 2009a) study, i.e., fake and duplicate events were identified and removed, polygons were specified within each of which one or more of the catalogues or data files have validity, and existing magnitudes and intensities were converted to M _w. Algorithms to compute M _w are based on relations provided locally, or more commonly on those derived by Grünthal et al. (J Seismol 13:517?C541, 2009a) or in the present study. The homogeneity of EMEC with respect to M _w for the different constituents was investigated and improved where feasible. EMEC contains entries of some 45,000 earthquakes. For each event, the date, time, location (including focal depth if available), intensity I ₀ (if given in the original catalogue), magnitude M _w (with uncertainty when given), and source (catalogue or special study) are presented. Besides the main EMEC catalogue, large events before year 1000 in the SE part of the investigated area and fake events, respectively, are given in separate lists.  相似文献   

Harmonization check of M w within the central, northern, and northwestern European earthquake catalogue (CENEC)     

Gottfried Grünthal  Dietrich Stromeyer  Rutger Wahlström 《Journal of Seismology》2009,13(4):613-632

Large data sets covering large areas and time spans and composed of many different independent sources raise the question of the obtained degree of harmonization. The present study is an analysis of the harmonization with respect to the moment magnitude M _w within the earthquake catalogue for central, northern, and northwestern Europe (CENEC). The CENEC earthquake catalogue (Grünthal et al., J Seismol, 2009) contains parameters for over 8,000 events in the time period 1000–2004 with magnitude M _w ≥ 3.5. Only about 2% of the data used for CENEC have original M _w magnitudes derived directly from digital data. Some of the local catalogues and data files providing data give M _w, but calculated by the respective agency from other magnitude measures or intensity. About 60% of the local data give strength measures other than M _w, and these have to be transformed by us using available formulae or new regressions based on original M _w data. Although all events are thus unified to M _w magnitude, inhomogeneity in the M _w obtained from over 40 local catalogues and data files and 50 special studies is inevitable. Two different approaches have been followed to investigate the compatibility of the different M _w sets throughout CENEC. The first harmonization check is performed using M _w from moment tensor solutions from SMTS and Pondrelli et al. (Phys Earth Planet Inter 130:71–101, 2002; Phys Earth Planet Inter 164:90–112, 2007). The method to derive the SMTS is described, e.g., by Braunmiller et al. (Tectonophysics 356:5–22, 2002) and Bernardi et al. (Geophys J Int 157:703–716, 2004), and the data are available in greater extent since 1997. One check is made against the M _w given in national catalogues and another against the M _w derived by applying different empirical relations developed for CENEC. The second harmonization check concerns the vast majority of data in CENEC related to earthquakes prior to 1997 or where no moment tensor based M _w exists. In this case, an empirical relation for the M _w dependence on epicentral intensity (I ₀) and focal depth (h) was derived for 41 master events, i.e., earthquakes, located all over central Europe, with high-quality data. To include also the data lacking h, the corresponding depth-independent relation for these 41 events was also derived. These equations are compared with the different sets of data from which CENEC has been composed, and the goodness of fit is demonstrated for each set. The vast majority of the events are very well or reasonably consistent with the respective relation so that the data can be said to be harmonized with respect to M _w, but there are exceptions, which are discussed in detail.  相似文献   

Effect of macrofaunal bioturbation on bacterial distribution in marine sandy sediments, with special reference to sulphur-oxidising bacteria     

Marisol Goi-Urriza  Xavier de Montaudouin  Rmy Guyoneaud  Guy Bachelet  Rutger de Wit 《Journal of Sea Research》1999,41(4):170

We have studied the impact of the bioturbating macrofauna, in particular the lugworm Arenicola marina and the bivalve Cerastoderma edule, on abundances and distribution patterns of total bacteria and of bacteria of selected functional groups in sandy intertidal sediments. The selected groups comprised the colourless sulphur-oxidising bacteria and the anoxygenic phototrophic bacteria, which are expected to occupy small zones at the oxygen–sulphide interface in stable (non-bioturbated) sediments. The presence of a wooden wreck buried in the sediment at 10 cm depth within a large area of intertidal sand flat colonised by lugworms provided a unique opportunity to confront field observations with laboratory simulations. The site with the wooden wreck, which was used as control site, was devoid of both A. marina and C. edule, while the composition of the rest of the zoobenthic community was rather similar to that of the surrounding area. In the field, the density of total bacteria was approximately one order of magnitude higher in the control site than in the natural (bioturbated) site. This can be explained by the higher contents of silt and clay particles (higher surface-area/volume ratio) and higher total organic-carbon contents found at the control site. It appears that the presence of macrofauna affects sedimentation processes, which indirectly influence bacterial dynamics. Samples from the control site have been incubated in the laboratory with A. marina and C. edule added (bioturbated core), while an unamended core served as a control. The laboratory experiments contrasted with the field observations, because it was found that total bacteria were actually higher in the deeper layers of the bioturbated core. Moreover, the populations were more homogeneous (less stratified) and colourless sulphur bacteria were on average less numerous in the bioturbated core. In general, laboratory incubations resulted in a decrease of total bacteria with a concomitant increase of colourless and phototrophic sulphur-oxidising bacteria and thus in modifications of the bacterial community structure. Hence, our results demonstrate that care must be taken in extrapolating results from laboratory experiments (e.g. mesocosm research) to field situations.  相似文献   

Formation and fragmentation of a late Miocene supradetachment basin in central Crete: implications for exhumation mechanisms of high‐pressure rocks in the Aegean forearc     

Willem Jan Zachariasse  Douwe J.J. van Hinsbergen  Anne Rutger Fortuin 《Basin Research》2011,23(6):678-701

We present a new lithostratigraphy and chronology for the Miocene on central Crete, in the Aegean forearc. Continuous sedimentation started at ～10.8 Ma in the E–W trending fluvio‐lacustrine Viannos Basin, formed on the hangingwall of the Cretan detachment, which separates high‐pressure (HP) metamorphic rocks from very low‐grade rocks in its hangingwall. Olistostromes including olistoliths deposited shortly before the Viannos Basin submerged into the marine Skinias Basin between 10.4 and 10.3 Ma testifies to significant nearby uplift. Uplift of the Skinias Basin between 9.7 and 9.6 Ma, followed by fragmentation along N–S and E–W striking normal faults, marks the onset of E–W arc‐parallel stretching superimposed on N–S regional Aegean extension. This process continued between 9.6 and 7.36 Ma, as manifested by tilting and subsidence of fault blocks with subsidence events centred at 9.6, 8.8, and 8.2 Ma. Wholesale subsidence of Crete occurred from 7.36 Ma until ～5 Ma, followed by Pliocene uplift and emergence. Subsidence of the Viannos Basin from 10.8 to 10.4 Ma was governed by motion along the Cretan detachment. Regional uplift at ～10.4 Ma, followed by the first reworking of HP rocks (10.4–10.3 Ma) is related to the opening and subsequent isostatic uplift of extensional windows exposing HP rocks. Activity of the Cretan detachment ceased sometime between formation of extensional windows around 10.4 Ma, and high‐angle normal faulting cross‐cutting the detachment at 9.6 Ma. The bulk of exhumation of the Cretan HP‐LT metamorphic rocks occurred between 24 and 12 Ma, before basin subsidence, and was associated with extreme thinning of the hangingwall (by factor ～10), in line with earlier inferences that the Cretan detachment can only explain a minor part of total exhumation. Previously proposed models of buyoant rise of the Cretan HP rocks along the subducting African slab provide an explanation for extension without basin subsidence.  相似文献   

Distribution of the energy release, b-values and seismic hazard in Egypt     

A. El-Sayed  R. Wahlström 《Natural Hazards》1996,13(2):133-150

A review of the seismicity and seismic history of Egypt indicates areas of high activity concentrated along Oligocene-Miocene faults. This supports the idea of recent activation of the Oligocene-Miocene stress cycle. There are similarities in the spatial distribution of recent and historical epicenters. Destructive earthquakes in Egypt are mostly concentrated in the highly populated areas of the Nile Valley and Nile Delta. Some big earthquakes located near the plate boundary as far away as Turkey and Crete were strongly felt in Egypt. The distribution of the energy release shows a possible tectonic connection between active zones in Egypt and the complicated tectonic zones in Turkey and Crete through geologically verified fault systems. The distribution of intensity shows a strong directivity along the Nile Valley. This is due to the presence of a thick layer of loose sediments on top of the hard rock in the Nile Valley graben. The distribution of b-values indicates two different zones, comparable with stable and unstable shelf areas. Stress loads in the northern Red Sea and northern Egypt are similar. Geologically, northern Egypt is a part of the Unstable Shelf area. The probability to have an earthquake with intensity V or larger within 94 years is more than 80% in the Nile Valley and Nile Delta areas, Egypt-Mediterranean coastal area, Aswan High Dam area, Gulf of Aqaba-Levant Fault zone and in the oil fields of the Gulf of Suez. The maximum expected intensity in these areas and within the same period is V–VI for a 80% probability and VII–VIII+ for a 10% probability. Intensity VIII–IX has been reported for several earthquakes in both historical and recent time.  相似文献   

Arm regeneration frequency in eight species of ophiuroidea (Echinodermata) from European sea areas     

Mattias Sköld  Rutger Rosenberg 《Journal of Sea Research》1996,35(4):353-362

Eight ophiuroid species, six from the northern Kattegat-eastern Skagerrak and three from the northern Adriatic Sea, were examined for regeneration of arms. The species were separated into groups based upon mode of feeding and habitat. Comparison between groups collected in the northern Kattegat-eastern Skagerrak showed that infaunal suspension- and deposit-feeding species (Amphiura filiformis and A. chiajei) had significantly more scars per arm (mean number 0.78) than epibenthic suspension feeders (Ophiothrix fragilis and Ophiocomina nigra, 0.29) or epibenthic carnivores and deposit feeders (Ophiura ophiura and O. albida, 0.13). Spatial variation in arm regeneration incidence was found between sampling sites in the northern Kattegat-eastern Skagerrak for Amphiura filiformis and in the northern Adriatic Sea for Ophiothrix quinquemaculata. The ash-free dry weight (AFDW) and nitrogen (N) contents were measured in arms of six species of brittle-stars from the northern Kattegat-eastern Skagerrak. Differences between species were found, with highest concentrations of AFDW and N in Amphiura filiformis, intermediate in A. chiajei, Ophiocomina nigra and Ophiothrix fragilis, and lowest in Ophiura ophiura and O. albida. As the infaunal suspension- and deposit-feeding brittle-stars (Amphiura spp.) had the highest proportions of damaged arms and highest AFDW and N contents in their arms in this comparison, it is suggested that selective cropping of arms by demersal fish is the main cause of arm damage on Amphiura spp. in this area.  相似文献