Regionaler Klimawandel Sachsen

Goal and Background

Since consequences of global climate change include even contradicting directions and trends in different regions and seasons, regional studies are a necessity to understand regional problems and risks. Extreme precipitation is a highly variable climate element in time and space with serious economic and ecological impacts. The analysis of changes in the Saxonian precipitation characteristics is one constituent in our understanding of global climate change and regional climate-related risk assessment.

Methods

Changes of regional precipitation patterns and their extremes were analysed based upon data from 21 stations in Saxony from 1934 to 2000. Eighteen stations delivered 50-year data sets (1951–2000) and three stations (Altmörbitz, Chemnitz, Neuhausen) delivered daily precipitation data over 67 years (1934–2000). Differentiated by season and half-year periods, trends were calculated for the relevant parameters by linear regression. The trend significance was determined by the non-parametric Mann-Kendall-trend test.

Results and Conclusion

In the summer half of the year, distinctively more dry conditions developed. Over the same period, the winter half of the year became more wet. Regarding trends of extreme precipitation, a strong dependency to the size of the choosen treshold value exists. During the summer, size and excess frequency of the 90^th and 95^th percentiles have increased, whereas they decreased in the winter. On the other hand, the half year trends of the 99^th percentile are predominantly positive. Particularly the trend towards more dry conditions in summer is of substantial relevance for the economy and water management.

Recommendations and Perspective

The additional analysis of further precipitation data sets, provided by the Saxonion Climate database, will advance the regional accuracy of the presented findings. In addition work on the adjustment of an extreme distribution to daily and monthly precipitation sums is needed, and an effect-related definition of dry periods needs to be developed.     

Length-weight relationships and coefficient of condition of Euphausia superba and Thysanoessa macrura (Crustacea: Euphausiacea) in southwest Indian Ocean during summer

Samples of antarctic euphausiids, Euphausia superba and Thysanoessa macrura were obtained during the MD 25 FIBEX expedition of the R. V. Marion Dufresne, in February 1981, to the southwest Indian Ocean. Individual and mean coefficients of condition (K _m) were calculated from variations in weight as a function of total length and of carapace length. In E. superba, no significant differences were found as a function of sex or development stage in either total length and weight or carapace length and weight. In T. macrura, a significant allometric difference emerged in the wet weight of juveniles, males and females as a function of total length, and in wet weight as a function of carapace length between adults and subadults. In both E. superba and T. macrura, wet weight as a function of total length differed significantly among stations, and also between species, with a greater weight increase for T. macrura in summer. The coefficients of condition calculated for all wet weight-total length relationships showed that the morphologically different Group II males were heavier than Group I males and mature females. K _m in T. macrura was higher for females than for juveniles or males, indicating a greater weight gain by the females. These differences probably reflect real differences in physiology and may affect the distribution of these two species.     

Quecksilber Erfassung von Immissionswirkungen Biomonitoring mit der Standardisierten Graskultur: Eignungstest

An approach to biomonitoring of immission-induced mercury contents (= immission effects) in standardized grass cultures was made at locations with different settlement structures and in the vicinity of two waste incineration plants in the context of a research project dealing with “Active biomonitoring of immission effects in the testing area of Munich”. In 1992, mercury could be found in most grass samples using the method of cold vapor atomic absorption spectrometry (CVAAS) with an analytical detection limit of 20 µg/kg dry mass. With a new detection limit of 5 µg/kg dry mass attained by a better analytical procedure, mercury could be detected in all grass samples of 1993. An influence of the two examined waste incineration plants on the mercury content in grass could not be detected, although a relationship between mercury contents in the standardized grass culture and settlement structures is indicated.     

Symbiontic bacteria in the gut of the blood-sucking Antarctic fish parasite Gnathia calva (Crustacea: Isopoda)

Structure and ultrastructure of the digestive tract of the ectoparasitic stages of the Antarctic isopod Gnathia calva, collected in the Weddell Sea and around the Antarctic Peninsula in the 1984–1985 season, are briefly described. There are only two digestive glands, with an ultrastructure similar to that of other isopods. The gut is divided into six regions: oesophagus, stomach, dilatable reservior for sucked-in blood, sphincter, rectal vesicle with symbiontic bacteria, and rectum. The highly dilatable anterior hindgut (reservoir) takes part in the resorption of nutrients and stores lipids and glycogen. The rectal vesicle has an epithelium with all the features of an organ with high metabolism and the capacity for the transportation of small molecules. The surface is increased by irregular microvilli. A very thin intima and a basal labyrinth are present. The presence of symbiontic bacteria is discussed in correlation with the haematophagous nutrition of G. calva.     

Diet of some Antarctic nudibranchs (Gastropoda,Opisthobranchia, Nudibranchia)

Austrodoris kerguelenensis feeds on sponges of the genera Rosella and Scolymastra; Aegires albus, on Hexactinellida (Porifera); and Tritoniella belli, probably on non-determined synascidians. Bathydoris clavigera and B. hodgsoni are omnivorous.     

Anaerobic metabolism of the common cockle Cardium edule

Changes in the level of the adenylates (ATP, ADP, AMP), arginine phosphate, arginine, octopine, D-lactate, succinate, and aspartate were determined in the foot of Cardium edule, after 12 h of anoxia and after aerobic recovery for up to 12 h. Control levels of the adenylates, the calculated energy charge and the arginine phosphate content were restored after about 1 h of recovery. On the other hand, the recovery of the D-lactate, succinate, and aspartate pools was a slow process, taking place over about 12h.     

Verteilung chemischer Elemente in der Nahrung und Milch stillender Mütter

Goal and Scope

The transfer of various chemical elements from maternal food into human milk was investigated. Transfer factors (hereafter TF) food/mother’s milk were taken to represent those nuclides pertinent to radiation protection in order to estimate possible radioactive burdens of breast-fed babies.

Methods

A total of 23 mothers, mainly from the Euroregion Neisse (PL, CZ, D; all being in their mature phases of lactation), took part in this study (1998–2001), for time periods between two to eight weeks (8805 samples were analyzed). The diurnal uptake of elements was determined by the duplicate method.

Results and Conclusions

TF values determined for Ag, Au, Ba, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, I, La, Mn, Mo, Nb, Ni, P, Pb, Ra, Rb, Re, Ru, Sb, Sr, Te, Th, Ti, U_o, Y, Zn, Zr were theoretically analyzed with the following result: metal ions transfer into mother’s milk mainly in coordinated states (i.e. bound to anionic ligands), with TF values which increase according to complex stabilities. Therefore it can be assessed that neither Cd nor Ba, both forming only weak complexes, pose hazards to breastfed children.

Outlook

There are relationships between transfer factors pertaining to certain elements and the amounts of others consumed by the mother; i.e. (changes in) consumption of one element influence the transfer towards women’s milk of another element. Accordingly, strategies can be developed to keep off hazardous substances — including fissiogenic radionuclides — from milk which is far more efficient than traditional isotopic dilution; however, iodide tablets are useful here, too.     

The migrating herdsman Dolichoderus (Diabolus) cuspidatus: an ant with a novel mode of life

Summary The Malayan ant Dolichoderus cuspidatus lives in obligatory symbiosis with the pseudococcid Malaicoccus formicarii and other species of the same genus. The assemblies, which may be encountered up to 25 m away from the nest, are constantly covered with a great number of worker ants who protect them and receive honeydew. In the event of heavy rain the workers from a dense protective cluster, clinging to each other on top of the mealybugs. Neither hunting behavior nor active search for protein sources was observed in D. cuspidatus, although dead insects were accepted as food. When not searching for new plants, the activity of the ants outside the colony is limited to visiting the mealybugs. During the night and parts of the day the ants stay in their nest. Ant colonies deprived of their mealybugs are not viable due to their dependence on the symbiosis and because of the competition of other ants. Antless M. formicarii are likewise not viable. The mealybugs are extremely polyphagous and feed on many different monocotylous and dicotylous angiosperms. They feed exclusively on the phloem sap of young plant parts which are rich in amino acids. Dolichoderus cuspidatus workers carry the mealybugs to such locations. During the picking up and carrying process both partners display typical behavioral patterns. The colonization of new feeding sites takes place in well organized mass processions. During the foundation or disintegration of large feeding complexes, provisional depots with waiting mealybugs and ants are set up. The pseudococcids are carried not only while shifting the feeding sites, but also whenever the colony leaves its former nesting site and especially when any kind of disturbance occurs. They are even carried about without any apparent external cause, which leads to the fact that, at all times of trail activity, on average more than 10% of all ants using the trails carry mealybugs. Mealybugs are also present within the nest, especially adult females which are viviparous and give birth to their offspring there. Censused colonies each consisted of over 10 000 workers, about 4000 larvae and pupae, more than 5000 mealybugs and one ergatoid queen. Male winged ants were observed in large numbers during the dry season (January–February) and during the rainy season (September–October). The colonies form typical clumplike bivouac nests consisting of clusters of workers clinging to each other, thereby covering the brood and the mealybugs. The nesting site is in no way altered by constructive measures and is mostly found close to the ground. The preferred nesting sites are clusters of leaves, and cavities in wood or soil, although a freely hanging bivouac between a few branches may be set up as well. As soon as the distance between the nest and the feeding site is too great the colony moves to the feeding site, whereby the brood and the mealybugs are carried along in a well organized manner. During such nest-moving the establishment of intermediate depots can be observed. A shift of nest sites can also be induced by disturbances or by a change in the microclimate in the vicinity of the nest. Colonies multiply by budding. The tropical rain forest continuously offers different sprouting plants, the utilization of which requires extreme mobility on the part of the consumer. The unique behavioral strategy of D. cuspidatus, to carry constantly their polyphagous mealybug partners to new feeding sites and to take the whole colony there has enabled this ant and its symbiont to occupy this rich food niche. Dolichoderus cuspidatus is the first true nomad found in ants.     

Terrestrische ökotoxikologische Testmethoden für die Tropen

Goal, Scope, and Background

Soil organisms play a crucial role in the terrestrial ecosystem. Plant Protection Products (PPPs) are known to affect soil organisms and might have negative impacts on soil functions influenced by these organisms. Little research has been done to day on the impact of PPs on tropical ecosystems. Therefore, in this study it was investigated whether fate and effects of pesticides differ between tropical and temperate regions and whether data generated under temperate conditions can be used for the Environmental Risk Assessment (ERA) in tropical regions.

Methods

In the first part of this study, the effects of two fungicides (Benomyl and Carbendazim) and one insecticide (lambda-Cyhalothrin) on soil invertebrates (i.e. earthworms and arthropods) were evaluated in laboratory tests modified for tropical conditions (temperature, soil, test species). Besides using some native species, the tests were done mainly with two (temperate and tropical) strains of earthworms (Eisenia fetida) and the peregrine isopod speciesPorcellionides pruinosus as standard test species. The chemicals were spiked in two natural and two artificial soils. A tropical artificial soil (TAS), containing a tropical fern product (Xaxim) or coconut coir dust as organic matter, was developed in this study.

Results and Conclusions

The results from the laboratory tests showed that all three test chemicals differed from those gained under temperate conditions. In the case of the fungicides the toxicity was lower but in the case of the insecticide higher under tropical than under temperate conditions. The native tropical earthwormPontoscolex corethrurus reacted more sensitively against Carbendazim in comparison to the standard test speciesEisenia fetida.

Recommendation and Perspective

Details of the environmental risk assessment of the three model chemicals based on the results of the laboratory described here (and including the results of higher tier tests (semi-field and field tests)) will be described in Part 2 of this series