Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial

Kjellström, E., Brandefelt, J., Näslund, J.‐O., Smith, B., Strandberg, G., Voelker, A. H. L. & Wohlfarth, B. 2010: Simulated climate conditions in Europe during the Marine Isotope Stage 3 stadial. Boreas, 10.1111/j.1502‐3885.2010.00143.x. ISSN 0300‐9483. State‐of‐the‐art climate models were used to simulate climate conditions in Europe during Greenland Stadial (GS) 12 at 44 ka BP. The models employed for these simulations were: (i) a fully coupled atmosphere–ocean global climate model (AOGCM), and (ii) a regional atmospheric climate model (RCM) to dynamically downscale results from the global model for a more detailed investigation of European climate conditions. The vegetation was simulated off‐line by a dynamic vegetation model forced by the climate from the RCM. The resulting vegetation was then compared with the a priori vegetation used in the first simulation. In a subsequent step, the RCM was rerun to yield a new climate more consistent with the simulated vegetation. Forcing conditions included orbital forcing, land–sea distribution, ice‐sheet configuration, and atmospheric greenhouse gas concentrations representative for 44 ka BP. The results show a cold climate on the global scale, with global annual mean surface temperatures 5 °C colder than the modern climate. This is still significantly warmer than temperatures derived from the same model system for the Last Glacial Maximum (LGM). Regional, northern European climate is much colder than today, but still significantly warmer than during the LGM. Comparisons between the simulated climate and proxy‐based sea‐surface temperature reconstructions show that the results are in broad agreement, albeit with a possible cold bias in parts of the North Atlantic in summer. Given a prescribed restricted Marine Isotope Stage 3 ice‐sheet configuration, with large ice‐free regions in Sweden and Finland, the AOGCM and RCM model simulations produce a cold and dry climate in line with the restricted ice‐sheet configuration during GS 12. The simulated temperature climate, with prescribed ice‐free conditions in south‐central Fennoscandia, is favourable for the development of permafrost, but does not allow local ice‐sheet formation as all snow melts during summer.     

Synergistic effects of an oil dispersant and low temperature on the freezing tolerance and solute concentrations of the blue mussel (Mytilus edulis L.)

Exposure of blue mussels ( Mytilus edulis L.) to an oil dispersant in increasing concentrations caused increased degree of injury in the mussels. The oil dispersant seemed to affect mechanisms responsible for the distribution of inorganic ions (Na⁺, K⁺, CI⁻) and free amino acids across the cell membranes. The dispersant caused a marked reduction in the ability of the mussels to survive freezing at −10°C. Freezing also caused more pronounced alterations in the transmembrane ionic distributions observed following exposure to the dispersant. This may indicate that the injuries caused by freezing are qualitatively the same as those caused by exposure to the dispersant alone, but brought into more extreme conditions. Thus, freezing appears to potentiate the effect of environmental pollutions by concentrating them in the fluid fraction of the frozen body fluids.     

Depositional environment and development of Danian bryozoan biomicrite mounds (Karlby Klint, Denmark)

The lower Danian bryozoan mounds exposed in the cliff at Karlby are described. Analyses of some sixty samples taken from a single mound reveal that the limestone is composed of about 30% of bryozoan fragments in a fine grained matrix. The texture and the grain-size distribution show that two distinct sedimentary facies can be recognized: (1) the northwestern flank and the basins with fine bryozoan fragments, a relatively small amount of matrix, and grain-supported texture; (2) the southeastern flank and the summit with coarse bryozoans, a larger amount of matrix and partly mud-supported texture. It is shown that the differences in the size of the bryozoan fragments are due to adaptations to changes in the water-movement rather than a result of significant transport. Thus, currents were roughly from the southeast producing more agitated water on the southeast flank and the summit and more gentle water on the northwest flank and in the basins. The unusual relationship between the velocity of the water-movement and the sedimentary facies is caused by an influence of the bryozoans on the depositional environment. On the southeast flank the higher current velocity favoured the growth of bryozoans, resulting in a relatively dense cover that was able to trap and bind the matrix. On the northwest flank the currents were slower and less favourable for growth, and the ability of the bryozoans to bind the sediment was correspondingly smaller.     

Physiological adaptations in Coleoptera on Spitsbergen

Metabolic rates and Q₁₀ values were determined for three species of Spitsbergen Coleoptera, Amara quenseli, Simplocaria metallica and Rhynchaenus flagellum . The beetles had metabolic rates which were elevated compared to values of Coleoptera from other regions. This is interpreted as an adaptation to the prevailing low temperatures and short activity period on Spitsbergen.
A. quenseli had rates of water loss comparable to values of beetles in temperate and tropical xeric habitats, indicating that the habitat of the beetles on Spitsbergen at least occasionally is xeric.
Determination of cold-hardiness parameters such as supercooling point and haemolymph melting point of A. quenseli beetles revealed that the beetles had values corresponding to those of active insects in the temperate and tropical region. They had no thermal hysteresis factors. Thus, during summer they show no physiological adaptations to cold.     

Ecophysiological studies on arthropods from Spitsbergen

The cold-hardiness, high temperature tolerance and metabolic activity of summer specimens of staphylinid beetles ( Atheta graminicola ), collembolans ( Onichiurus groenlandicus ), spiders ( Erigone arctica ), and prostigmatid mites ( Molgus littoralis ) from Spitsbergen were investigated. The animals displayed cold-hardiness and haemolymph melting points within the normal ranges for summer insects from temperate regions, but were less tolerant to high temperatures. Haemolymph from spiders and from one species of collembolans ( Isotoma sp.) was found to contain thermal hysteresis factors. The beetles, collembolans, and mites were found to have oxygen consumption rates above the values of their relatives in other climatic zones, whereas the spiders had values within the range of temperate arachnoids. The study supports the view that polar arthropods have activation energy values lower than those of temperate animals.     

Thermal hysteresis antifreeze agents in fishes from Spitsbergen waters

The occurrence of macromolecular antifreeze agents (so-called Thermal Hysteresis Factors) in blood plasma of fishes from Spitsbergen waters was investigated in August 1983, October 1984, and January 1986.
Thermal hysteresis was found in the plasma of three species of Spitsbergen fishes: shorthorn sculpin (Myoxocephalus scorpius) , polar cod (Boreogadus saida) , and sea snail (Liparis liparis) . This is the first time thermal hysteresis is reported from the sea snail. Seasonal changes in the amount of thermal hysteresis were observed in blood plasma of the shorthorn sculpin and the sea snail.
With the exception of the polar cod, blood plasma of deep water fishes displays no thermal hysteresis. The reason for this is probably that the polar cod also occurs in shallow ice laden sea water, where an'antifreeze'would be needed to protect against inoculative freezing.
No thermal hysteresis was observed in blood plasma of the saithe (Pollachius virens) , despite the fact that the saithe was observed swimming in ice laden sea water at a temperature of -1 to – 1.5°C under natural conditions, and was rapidly killed when it came into contact with ice in the laboratory. It is not known how the saithe survives in ice laden water under natural conditions.