Kinetics of hepatic phase I and II biotransformation reactions in eight finfish species

Hepatic microsomes and cytosols of channel catfish (Ictalurus punctatus), rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), red tilapia (Oreochromis sp.), largemouth bass (Micropterus salmoides), striped bass (Morone saxatilis), hybrid striped bass (M. saxatilis × M. crysops), and bluegill (Lepomis macrochuris) (n = 8) were used to study the kinetics of phase I (ECOD, EROD, PROD, BROD) and phase II (UDP-glucuronosyltransferase (UDPGT)-, sulfotransferase (ST)- and glutathione-s-transferase (GST)-mediated) reactions. The best catalytic efficiency for ECOD and GST activities was performed by channel catfish, Atlantic salmon, rainbow trout and tilapia. The highest EROD catalytic efficiency was for Atlantic salmon. None of the species had either PROD or BROD activities. Rainbow trout had very similar UDPGT catalytic efficiency to tilapia, channel catfish, Atlantic salmon, largemouth bass and bluegill. Sulfotransferase conjugation had no significant differences among the species. In summary, tilapia, channel catfish, Atlantic salmon and rainbow trout had the best biotransforming capabilities; striped bass, hybrid striped bass and bluegill were low metabolizers and largemouth bass shared some capabilities with both groups.     

Deep sediment transport induced by storms and dense shelf-water cascading in the northwestern Mediterranean basin

Downward particle fluxes and hydrodynamics in the northwestern Mediterranean basin were measured by a sediment trap and a current meter deployed at 2350 m depth, 250 m above bottom, from November 2003 to April 2005. During the winter of 2003–2004 there were high river discharges, two strong E–SE storms and several moderate storms and short periods of moderate dense shelf-water cascading during which dense shelf water did not reach the deep basin. Downward particle fluxes at the basin site were low during most of this winter but increased above one order of magnitude as a consequence of the strong storm and moderate cascading event that occurred in late February 2004. During the winter of 2004–2005, neither important river floods nor strong storms occurred but there were very intense and persistent dense shelf-water cascading events from February to April 2005. Dense shelf water, mixed with offshore convection water, reached the basin site in early March 2005, increasing downward particle fluxes by more than two orders of magnitude for more than 1 month. These observations indicate that events of significant sediment transport to the northwestern Mediterranean basin can be caused by severe winter E–SE storms associated with moderate cascading events or by exceptionally intense and persistent dense shelf-water cascading episodes alone. On the other hand, river floods, severe storms during water column stratification conditions (without cascading) and moderate storms concurrent with moderate dense shelf-water cascading did not generate sediment transport events able to reach the basin.     

Observational Study of Sunspot Oscillations in Stokes I,Q, U,and V

Time series of 2-dimensional spectro-polarmetric data were obtained with the intent of studying the temporal behavior of velocity, magnetic flux, and characteristics of the Stokes V profile in a small region of a larger sunspot. Full Stokes profiles in I, Q, U, and V were obtained. Velocity oscillations were found at frequencies of 3.3 mHz in each of the profiles. Acoustic power maps indicate that locations of highest power correspond to areas in which the polarization signal was greatest, therefore no conclusion about the type of wave mode participating in the oscillations can be made. Velocity amplitudes were I: 71 m s^–1, Q: 47 m s^–1, U: 65 m s^–1 and V: 86 m s^–1. Oscillatory behavior was also detected in longitudinal field strength, with an r.m.s. amplitude of 22 G, at 2.6 and 3.3 mHz. The power was localized at the umbral/penumbral boundary. A phase analysis indicates a –130° phase difference with Stokes V velocity oscillations at 3.3 mHz and a 75° difference at 2.6 mHz. Results are consistent with magnetic field lines swaying in response to a p-mode driver. No oscillatory behavior was seen in Stokes V asymmetry or amplitude splitting.     

Basic limnological characteristics of the shallow eutrophic lake Grimnitzsee (Brandenburg, Germany)

The medium shallow lake Grimnitzsee (maximum depth: 9.9 m; mean depth: 4.6 m; area: 7.7 · 10⁶ m²) which is situated in the biosphere reserve “Schorfheide-Chorin” in northern Brandenburg (Germany) was studied in 1994 and 1995. A bathymetric map of Grimnitzsee is given for the first time. The lake is usually polymictic although in 1994 and 1995 relatively long summer stratification was observed due to very high global radiation input. Nutrient concentration, light climate, oxygen status, phytoplankton biomass and the species composition of littoral diatoms characterize the lake as eutrophic. Special features deducible from the lake's polymictic character were the multiple development of aerobic or anaerobic strata above the sediment, the fast recovery of silicon concentration in the water column after diatom sedimentation, the importance of resuspension for the success of planktonic diatom populations, and an only moderate correlation between chlorophyll a concentration and light attenuation as well as seston dry weight probably due to the influence of suspended particles.     

On the natural variability of the pre-industrial European climate

We suggest that climate variability in Europe for the “pre-industrial” period 1500–1900 is fundamentally a consequence of internal fluctuations of the climate system. This is because a model simulation, using fixed pre-industrial forcing, in several important aspects is consistent with recent observational reconstructions at high temporal resolution. This includes extreme warm and cold seasonal events as well as different measures of the decadal to multi-decadal variance. Significant trends of 50-year duration can be seen in the model simulation. While the global temperature is highly correlated with ENSO (El Nino- Southern Oscillation), European seasonal temperature is only weakly correlated with the global temperature broadly consistent with data from ERA-40 reanalyses. Seasonal temperature anomalies of the European land area are largely controlled by the position of the North Atlantic storm tracks. We believe the result is highly relevant for the interpretation of past observational records suggesting that the effect of external forcing appears to be of secondary importance. That variations in the solar irradiation could have been a credible cause of climate variations during the last centuries, as suggested in some previous studies, is presumably due to the fact that the models used in these studies may have underestimated the internal variability of the climate. The general interpretation from this study is that the past climate is just one of many possible realizations and thus in many respects not reproducible in its time evolution with a general circulation model but only reproducible in a statistical sense.     

Multi-variable error correction of regional climate models

Climate change impact research needs regional climate scenarios of multiple meteorological variables. Those variables are available from regional climate models (RCMs), but affected by considerable biases. We evaluate the application of an empirical-statistical error correction method, quantile mapping (QM), for a small ensemble of RCMs and six meteorological variables. Annual and monthly biases are reduced to close to zero by QM for all variables in most cases. Exceptions are found, if non-stationarity of the model’s error characteristics occur. Even in the worst cases of non-stationarity, QM clearly improves the biases of raw RCMs. In addition, QM successfully adjusts the distributions of the analysed variables. To approach the question whether time series and inter-variable relationships are still plausible after correction, we evaluate the root-mean-square error (RMSE), autocorrelation and inter-variable correlation. We found improvement or no clear effect in RMSE and autocorrelation, and no clear effect on the correlation between meteorological variables. These results demonstrate that QM retains the quality of the temporal structure in time series and the inter-variable dependencies of RCMs. It has to be emphasised that this cannot be interpreted as an improvement and that deficiencies of the RCMs in those features are retained as well. Our results give some indication for the performance of QM applied to future scenarios, since our evaluation relies on independent calibration and evaluation periods, which are affected by climate variability and change. The effect of non-stationarity, however, can be expected to be larger in far future. We demonstrate the retainment of the RCM’s temporal structure and inter-variable dependencies, and large improvements in biases. This qualifies QM as a valuable, though not perfect, method in the interface between climate models and climate change impact research. Nonetheless, in case of no correlation between re-analysis driven RCM and observation, one should consider that QM does not correct this correlation.