Abundance and biomass of the benthic infauna of the North Sea

In 1986 participants of the Benthos Ecology Working Group of ICES conducted a synoptic mapping of the infauna of the southern and central North Sea. Together with a mapping of the infauna of the northern North Sea by Eleftheriou and Basford (1989, doi:10.1017/S0025315400049158) this provides the database for the description of the benthic infauna of the whole North Sea in this paper. Division of the infauna into assemblages by TWINSPAN analysis separated northern assemblages from southern assemblages along the 70 m depth contour. Assemblages were further separated by the 30, 50 m and 100 m depth contour as well as by the sediment type. In addition to widely distributed species, cold water species do not occur further south than the northern edge of the Dogger Bank, which corresponds to the 50 m depth contour. Warm water species were not found north of the 100 m depth contour. Some species occur on all types of sediment but most are restricted to a special sediment and therefore these species are limited in their distribution. The factors structuring species distributions and assemblages seem to be temperature, the influence of different water masses, e.g. Atlantic water, the type of sediment and the food supply to the benthos.

List of plant species found on Victoria Island

While engaged in geoecological field work on Victoria Island, 277 new plants could be recorded for the vicinities of Holman, Cambridge Bay, Wellington Bay, Mt. Pelly, Richardson Islands, Hadley Bay, and Minto lnlet; 8 of them were new for Victoria Island, 6 for the western Canadian arctic archipelago.

Spores, pollen and dinoflagellates in Cretaceous sediments of ODP Hole 129-802A

Lower Cretaceous and Jurassic sediments from Ocean Drilling Program Leg 129 (Sites 800, 801, and 802) and Deep Sea Drilling Project Sites 167, 195, 196, and 463 were analyzed for palynomorphs. In contrast to Atlantic occurrences, all Cretaceous pelagic sediments at these sites in the Pacific are barren of preserved palynomorphs. This absence of palynomorphs appears to be independent of facies, sedimentation rate, paleodepth, and paleolatitude. Except for one sample, the dinocyst-bearing sediments also contain spores and pollen grains. The only palynomorphs observed were in redeposited material having sources near former emergent seamounts. Among the dinoflagellate cysts at Site 802, Dingodinium cerviculum, Odontochitina operculata, Canninginopsis colliveri, and Oligosphaeridium complex are the most important species. Based on the presence of these species and their known biostratigraphic ranges, this basal interval of Site 802 is considered to be Aptian/earliest Albian in age. The lack of dinocysts within the Pacific pelagic sediments may be the result of ubiquitous oxygenated bottom waters throughout the Cretaceous or may indicate that open-marine dinoflagellate populations in this ocean did not produce cysts.

Neogene diatoms of the Japan Sea

A series of excellent upper Miocene through Quaternary diatomaceous sequences recovered at four sites during Leg 127 was examined for diatoms. The diagenetic transition from opal-A to opal-CT is a diachronic horizon from the uppermost part of the Denticulopsis katayamae Zone (8.5 Ma) at Hole 797B to the uppermost part of the Neodenticula kamtschatica Zone (5.73 Ma) at Hole 795A. The diatom zonation of Koizumi (1985) best divides the upper Miocene to Quaternary sequences above the opal-A/opal-CT boundary and also is useful to date carbonate concretions including diatoms below the boundary. Forty diatom datum levels were evaluated biostratigraphically based on the sediment accumulation rate curve, and several isochronous datum levels are newly proposed for the Japan Sea area. A warm-water current did not penetrated into the Japan Sea through the Tsushima strait during the late Miocene and Pliocene time, because subtropical warm-water diatoms are essentially not present in such sediment samples. The occurrences of diatom are cyclic throughout the Quaternary sediments and are affected by eustatic sea level changes.

Miocene to Holocene diatom biostratigraphy of ODP Leg 105 sites

Diatoms occur sporadically in lower Miocene to Holocene sediments recovered at ODP Site 645 and in upper Pliocene to Holocene sediments at ODP Site 646. The diatom assemblage at Site 645 contains rare stratigraphic indicators. Fragmentation of frustules and the occurrence of species characteristic of high-latitude shelf, upper-slope environments suggest current transportation from the shelf. The diatom abundance and preservation at Site 646 probably reflect climatic changes and are also affected by dissolution, but it is not possible to detect the dominant factor. Therefore, the stratigraphic ranges of the primary and secondary biostratigraphic indicators are often unreliable.

Pollen record and age determination of sediment core Fersina 2

Pollen analysis of samples taken from the core of the water well Fersina 2 (Adige Valley, Prov. Trento, NE Italy) did not reveal any indication of an interglacial or Holocene age of the uppermost 190 m in the sediment sequence deposited in the over-deepened Adige River Valley. The sediment sequence dates entirely from late-glacial times. Four radiocarbon ages of pieces of wood indicate that about 165 m of the upper part of the profile are of Younger Dryas age. The lower part of the sequence dates from the Allerød or Bølling/Allerød and a preceding cold phase, probably the Oldest Dryas. Accordingly the deposition of the sequence took about 2500 or 3500 years and was completed long before the onset of the Neolithic. Our results are in excellent agreement with findings in other formerly glaciated alpine valleys (e.g. the Traun, Salzach and Enns valleys in the Northern Alps). The final depth of the Fersina 2 well is 190 m. It is very likely that the sediment sequence found below this level in the nearby 423 m deep Fersina 1 well was also deposited after the deglaciation of the Adige Valley at the end of the last glacial period.

Pollen and macroremains from three sediment cores from Göttingen, Germany

In a borehole in the southern outskirts of the town of Göttingen, limnic sediments of several Pleistocene warm periods occur intercalated with coarse solifluction debris and gravel of the river Leine. Pollen analysis of the limnic sediments in a borehole at Ottostrasse gave evidence of three warm periods of interglacial character, followed by three interstadial phases. The warm phases are separated one from another by stadial phases with, at least in one case, indications of periglacial solifluction. This sequence belongs to the Brunhes magnetic epoch. The pollen data allow to exclude an Eemian or Holsteinian age of the warm period sediments. Thus a Cromerian age is assumed, though the exact position of the newly described warm periods within the ''Cromerian'' remains uncertain. A section in a borehole at Akazienweg is of Holsteinian age.

Tab. 1: Distribution of important species along a topographical transect in a siliceous boulder talus near Vårsolbukta, Bellsund

The vegetation pattern of siliceous boulder snow beds (Dicranoweision crispulae all. nov. prov.) of Svalbard was investigated by using transect studies in several places on Spitsbergen. Dicranoweisia crispula is the best diagnostic species. It is found throughout the whole snow bed, is a good differential species against Racomitrium lanuginosum communities above the snow bed, and does not occur on basic rocks. Three Andreaea spp. are also among the most important members of these communities. They are all acidophilous, but with different pH preferences. Eight weakly acidophilous species lacking both on basic and on gneissic/granitic rocks, are reported from Svalbard. Half of these are characteristic species of Dicranoweision crispulae on Svalbard.

Response of nannoplankton to major changes in sea-surface temperature at the South Chatham Rise, southeastern New Zealand

A high-resolution history of paleoceanographic changes in the subpolar waters of the southern margin of the Subtropical Convergence Zone during the last 130 kyr, is present in foraminiferal assemblages of DSDP Site 594. The foraminifera indicate that sea-surface temperatures during the Last Interglacial Climax were warmer than today, and that between substage 5d through to the end of isotope stage 2, temperatures were mostly cooler than Holocene temperatures. The paleotemperatures suggest that (1) the Subtropical Convergence was located over the site during substage 5e, later moving further north, then moving southwards to near the site during the Holocene, and (2) the Polar Front was positioned over the Site during glacial stages 6, 4, 2 and possibly parts of stage 3. Several major events are indicated by the nannofloral assemblages during these large changes in sea-surface temperature and associated reorganization of ocean circulation. First, the time-progressive trends between E. huxleyi and medium to large Gephyrocupsa are unique to this site, with E. huxleyi dominating over medium Gephyrocupsa during stages 5c-a, middle part of stage 4 and after the middle point of stage 3. This unusual trend may (at least partly) be caused by the shift of the Polar Front across the site. Second, upwelling flora (E. huxleyi and small placoliths) increase in abundance during stages 1, 3 and 5, suggesting that upwelling or disturbance of water stratification took place during the interglacials. Thirdly, there are no significant differences between the distribution patterns of the various morphotypes of medium to large Gephyrocupsu, and the combined value of all medium Gephyrocupsu increases in abundance during glacials (stages 2 and 4 and the end of stage 6), similar to the abundance trends in benthic foraminifera. Finally, subordinate nannofossil taxa also show distinctive climatic trends during the last glacial cycle: (1) Syrucosphaera spp. are present in increased abundance during warmer extremes in climate (substages 5e, 5a, and stage 1); (2) Coccolithus pelagicus and Culcidiscus leptoporus dominate the subordinate nannofossil taxa, and their relative proportions seem to provide a useful paleoceanographic index, with C. pelagicus dominating when the Polar Front Zone is over the site (stages 6, 4 and 2), whilst C. leptoporus is relatively more abundant when the STC is positioned over the site (stages 1 and 5e). Increased abundance of C. pelagicus also can indicate intensified coastal upwelling.