Using Satellite Remote Sensing to Estimate the Colored Dissolved Organic Matter Absorption Coefficient in Lakes

Given the importance of colored dissolved organic matter (CDOM) for the structure and function of lake ecosystems, a method that could estimate the amount of CDOM in lake waters over large geographic areas would be highly desirable. Satellite remote sensing has the potential to resolve this problem. We carried out model simulations to evaluate the suitability of different satellite sensors (Landsat, IKONOS, and the Advanced land Imager [ALI]) to map the amount of CDOM in concentration ranges that occur in boreal lakes of the Nordic countries. The results showed that the 8-bit radiometric resolution of Landsat 7 is not adequate when absorption by CDOM at 420 nm is higher than 3 m⁻¹. On the other hand, the 16-bit radiometric resolution of ALI, a prototype of the next generation of Landsat, is suitable for mapping CDOM in a wider range of concentrations. An ALI image of southern Finland was acquired on 14, July 2002 and in situ measurements were carried out in 15 lakes (18 stations). The results showed that there is a high correlation (R² = 0.84) between the 565 nm/660 nm ALI band ratio and the CDOM absorption coefficient in lakes. Analysis of 245 lakes in the acquired satellite image showed a normal distribution of CDOM concentration among the lakes. However, the size distribution of lakes was highly skewed toward small lakes, resulting in the CDOM concentration per unit lake area being skewed toward high values. We showed that remote sensing enables synoptic monitoring of the CDOM concentration in a large number of lakes and thus enables scaling up to the level of large ecosystems and biomes.     

Microsatellite markers reveal clear geographic structuring among threatened noble crayfish (Astacus astacus) populations in Northern and Central Europe

Noble crayfish (Astacus astacus L.), the most highly valued freshwater crayfish in Europe, is threatened due to a long-term population decline caused mainly by the spread of crayfish plague. Reintroduction of the noble crayfish into restored waters is a common practice but the geographic and genetic origin of stocking material has rarely been considered, partially because previous genetic studies have been hampered by lack of nuclear gene markers with known inheritance. This study represents the first large scale population genetic survey of the noble crayfish (633 adults from 18 locations) based on 10 newly developed microsatellite markers. We focused primarily on the Baltic Sea area (Estonia, Finland and Sweden) where the largest proportion of the remaining populations exists. To allow comparisons, samples from the Black Sea catchment (the Danube drainage) were also included. Two highly differentiated population groups were identified corresponding to the Baltic Sea and the Black Sea catchments, respectively. The Baltic Sea catchment populations had significantly lower genetic variation and private allele numbers than the Black Sea catchment populations. Within the Baltic Sea area, a clear genetic structure was revealed with population samples corresponding well to their geographic origin, suggesting little impact of long-distance translocations. The clear genetic structure strongly suggests that the choice of stocking material for re-introductions and supplemental releases needs to be based on empirical genetic knowledge.     

Factors controlling long-term changes of the eutrophicated ecosystem of Pärnu Bay,Gulf of Riga

Phytoplankton, mesozooplankton, mysids and fish larvae were studied during 15–29 annual cycles measured weekly to monthly in Pärnu Bay, the Gulf of Riga. The monthly variability of the biological data was related to temperature, ice conditions, salinity, influx of nutrients, the North Atlantic Oscillation (NAO) index, cloudiness and solar activity. Phytoplankton development was mainly a function of the NAO index. For the whole study period the abundance of zooplankton increased with increasing water temperature and solar activity. Significant correlations between phytoplankton and zooplankton densities were found until 1990. After the invasion of the predatory cladoceran Cercopagis pengoi in 1991, the zooplankton community was likely to be regulated by the introduced species rather than phytoplankton dynamics. The increased abundances of rotifers and copepods triggered the increase in mysid densities. The development of herring larvae was positively affected by the high density of copepods and rotifers but also by increased eutrophication. Until 1990 there was no significant relationship between the density of zooplankton and herring larvae. A negative relationship between the density of zooplankton and herring larvae in the 1990s suggests that the major shift in zooplankton community resulted in food limitation for herring larvae. The results indicated that (1) atmospheric processes in the northern Atlantic explain a large part of the interannual variation of the local phytoplankton stock, (2) trophic interactions control the development of pelagic communities at higher trophic levels, and (3) the introduction of an effective intermediate predator has repercussions for the whole pelagic food web in Pärnu Bay.     

First records of the non-indigenous signal crayfish (<Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis>) and its threat to noble crayfish (<Emphasis Type="Italic">Astacus astacus</Emphasis>) populations in Estonia

This study gives an overview of status and distribution of signal crayfish (Pacifastacus leniusculus), the first NICS in Estonia and its influence on native noble crayfish (Astacus astacus) populations. The first specimen of signal crayfish was caught during the monitoring of noble crayfish in North Estonia in 2008. The signal crayfish has since been found in three additional sites. Test fishing has indicated that the abundance of signal crayfish has been fluctuating between years and among localities. It has had strong negative impact on abundance of one noble crayfish population. The disconnected distribution of signal crayfish strongly suggests that these populations are the result of human-assisted introductions. Real-time PCR analyses proved that signal crayfish carry the causative agent of the crayfish plague, an oomycete Aphanomyces astaci, thus contributing to its spread. Mortalities in noble crayfish populations had been caused by A. astaci strains from A, B and E genotype group.     

Daily Liquorice Consumption for Two Weeks Increases Augmentation Index and Central Systolic and Diastolic Blood Pressure

Background

Liquorice ingestion often elevates blood pressure, but the detailed haemodynamic alterations are unknown. We studied haemodynamic changes induced by liquorice consumption in 20 subjects versus 30 controls with average blood pressures of 120/68 and 116/64 mmHg, respectively.

Methods

Haemodynamic variables were measured in supine position before and after two weeks of liquorice consumption (daily glycyrrhizin dose 290–370 mg) with tonometric recording of radial blood pressure, pulse wave analysis, and whole-body impedance cardiography. Thirty age-matched healthy subjects maintaining their normal diet were studied as controls.

Results

Two weeks of liquorice ingestion elevated peripheral and central systolic and diastolic blood pressure (by 7/4 and 8/4 mmHg, 95% confidence intervals [CI] 2-11/1-8 and 3-13/1-8, respectively, P<0.05), and increased extracellular volume by 0.5 litres (P<0.05 versus controls). Also augmentation index adjusted to heart rate 75/min (from 7% to 11%, 95% CI for change 0.3-7.5, P<0.05) and aortic pulse pressure (by 4 mmHg, 95% CI 1-7, P<0.05) were elevated indicating increased wave reflection from the periphery. In contrast, peripheral (−3/−0.3 mmHg) and central blood pressure (−2/−0.5 mmHg), aortic pulse pressure (−1 mmHg), and augmentation index adjusted to heart rate 75/min (from 9% to 7%) decreased numerically but not statistically significantly without changes in extracellular volume in the control group. Heart rate, systemic vascular resistance, cardiac output, and pulse wave velocity did not differ between the groups.

Conclusions

Two weeks of daily liquorice consumption increased extracellular volume, amplified pressure wave reflection from the periphery, and elevated central systolic and diastolic blood pressure.

Trial Registration

EU Clinical Trials Register EudraCT 2006-002065-39</url>ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01742702","term_id":"NCT01742702"}}NCT01742702     

Male-biased size dimorphism in ichneumonine wasps (Hymenoptera: Ichneumonidae) – the role of sexual selection for large male size

Abstract.  1. Sexual differences in body size are expected to evolve when selection on female and male sizes favours different optima.
2. Insects have typically female-biased size dimorphism that is usually explained by the strong fecundity advantage of larger size in females. However, numerous exceptions to this general pattern have led to the search for selective pressures favouring larger size in males.
3. In this study, the benefits of large size were investigated in males of four species of ichneumonine wasps, a species-rich group of parasitoids, many representatives of which exhibit male-biased size dimorphism.
4. Mating behaviour of all ichneumonine wasps are characterised by pre-copulatory struggles, in the course of which males attempt to override female reluctance to mate. A series of laboratory trials was conducted to study the determinants of male mating success.
5. A tendency was found for larger males as well as those in better condition to be more successful in achieving copulations. Size dimorphism of the species studied, mostly male-biased in hind tibia length but female-biased in body weight, indicates that sexual selection in males favours longer bodies and appendages rather than larger weight.
6. The qualitative similarity of the mating patterns suggests that sexual selection cannot completely explain the considerable among-species differences in sexual size dimorphism.
7. The present study cautions against using various size indices as equivalents for calculating sexual size dimorphism.
8. It is suggested that female reluctance in ichneumonine wasps functions as a mechanism of female mate assessment.     

Localization of monoaminergic neurons in the central nervous system of Astacus astacus Linné (Crustacea)

Summary The cellular localization of biogenic monoamines in crustaceans was studied by means of a highly specific and sensitive fluorescence method devised by Falck and Hillarp. It was found that neurons displaying specific fluorescence in the central nervous system were confined to the protocerebrum, the medulla externa and interna and the ventral nerve cord. The method allows a distinction between the fluorophores of 5-hydroxytryptamine (and 5-hydroxytryptophan), which emit the yellow light, and the fluorophores deriving from the catecholamines (and DOPA), which emit the green light. Green-fluorescent neurons occurred abundantly in the aforementioned parts of the central nervous system while yellow-fluorescent neurons were sparsely present in the same parts.The present work has been carried out at the departments of Histology and Zoology at the University of Lund. The authors take great pleasure in expressing their warmest thanks for laboratory facilities, provided by Professors Erik Dahl (Zoological Institute) and Bengt Falck (Histological Institute).The research reported in this document has been sponsored by the Air Force Office of Scientific Research under Grant AF EOAR 66-14 through the European Office of Aerospace Research (OAR), United States Air Force and by a grant from the Swedish Natural Science Research Council 99-32 (nr 5995).     

Temperature responses of dark respiration in relation to leaf sugar concentration

Changes in leaf sugar concentrations are a possible mechanism of short‐term adaptation to temperature changes, with natural fluctuations in sugar concentrations in the field expected to modify the heat sensitivity of respiration. We studied temperature‐response curves of leaf dark respiration in the temperate tree Populus tremula (L.) in relation to leaf sugar concentration (1) under natural conditions or (2) leaves with artificially enhanced sugar concentration. Temperature‐response curves were obtained by increasing the leaf temperature at a rate of 1°C min^?1. We demonstrate that respiration, similarly to chlorophyll fluorescence, has a break‐point at high temperature, where respiration starts to increase with a faster rate. The average break‐point temperature (T_RD) was 48.6 ± 0.7°C at natural sugar concentration. Pulse‐chase experiments with ¹⁴CO₂ demonstrated that substrates of respiration were derived mainly from the products of starch degradation. Starch degradation exhibited a similar temperature‐response curve as respiration with a break‐point at high temperatures. Acceleration of starch breakdown may be one of the reasons for the observed high‐temperature rise in respiration. We also demonstrate that enhanced leaf sugar concentrations or enhanced osmotic potential may protect leaf cells from heat stress, i.e. higher sugar concentrations significantly modify the temperature‐response curve of respiration, abolishing the fast increase of respiration. Sugars or enhanced osmotic potential may non‐specifically protect respiratory membranes or may block the high‐temperature increase in starch degradation and consumption in respiratory processes, thus eliminating the break‐points in temperature curves of respiration in sugar‐fed leaves.     

Body build classes as a method for systematization of age-related anthropometric changes in girls aged 7-8 and 17-18 years

A total of 462 schoolgirls aged 7-8 and 17-18 years were examined anthropometrically (45 body measurements and 10 skinfolds) in a cross-sectional study. The data were processed in two age groups: 7-8-year-olds (n = 205) and 17-18-year-olds (n = 257). Relying on average height and weight in the groups, both groups were divided into five body build classes: small, medium, large, pyknomorphous and leptomorphous. In these classes, the differences in all other body measurements were compared, and in both age groups, analogous systematic differences were found in length, width and depth measurements and circumferences. This enabled us to compare proportional changes in body measurements during ten years, using for this ratios of averages of basic measurements and measurement groups in the same body build classes. Statistical analysis by the sign test revealed statistically significant differences between various body build classes in the growth of averages. Girls belonging to the small class differed from the girls of the large class by an essentially greater increase in their measurements. Our results suggest that the growth rate of body measurements of girls with different body build can be studied by the help of body build classification.