Diurnal and seasonal fluctuations in wood ant (Formica polyctena) nest temperature in two geographically distant populations along a south – north gradient

Temperature changes were recorded continuously in eleven nests of Formica polyctena located in Southern Finland and the Czech Republic. Nest temperatures were recorded in the Czech site from 2003 to 2005 and in Finland during 2004 – 2005. Seasonal changes in nest temperature were very similar in both locations. During summer, the ants maintained a relatively high and constant temperature in their nest in both locations. Summer nest temperatures in Finland were higher than those in Czech during 2004 –2005 but did not differ from those in Czech during 2003– 2004. This indicated that the geographical differences were less important than difference between seasons. Nest temperature peaked in June. During summer, daily temperature fluctuations were significantly lower in Finland than in Czechia probably due to shorter nights in Finland. Apparent differences in daily temperature patterns were found in nests with different moisture in both locations. In dry nests, temperature peaked in the evening and decreased overnight, whereas the apparent increase was delayed to the night in wet nests. The spring increase in temperature in wet nests was much steeper that that in the dry ones when whole spring period is considered. During one day, temperatures fluctuated much more in dry nests than in wet ones. These differences seem to be caused by differences in thermal capacity between dry and wet nests. Received 24 July 2006; revised 19 February 2007; accepted 19 May 2007.     

Coherent phenomena in photosynthetic light harvesting: part two—observations in biological systems

Considerable debate surrounds the question of whether or not quantum mechanics plays a significant, non-trivial role in photosynthetic light harvesting. Many have proposed that quantum superpositions and/or quantum transport phenomena may be responsible for the efficiency and robustness of energy transport present in biological systems. The critical experimental observations comprise the observation of coherent oscillations or “quantum beats” via femtosecond laser spectroscopy, which have been observed in many different light harvesting systems. Part Two of this review aims to provide an overview of experimental observations of energy transfer in the most studied light harvesting systems. Length scales, derived from crystallographic studies, are combined with energy and time scales of the beats observed via spectroscopy. A consensus is emerging that most long-lived (hundreds of femtoseconds) coherent phenomena are of vibrational or vibronic origin, where the latter may result in coherent excitation transport within a protein complex. In contrast, energy transport between proteins is likely to be incoherent in nature. The question of whether evolution has selected for these non-trivial quantum phenomena may be an unanswerable question, as dense packings of chromophores will lead to strong coupling and hence non-trivial quantum phenomena. As such, one cannot discern whether evolution has optimised light harvesting systems for high chromophore density or for the ensuing quantum effects as these are inextricably linked and cannot be switched off.     

Comparison between airborne pollens in Torino and Perugia (Italy) 1982–83–84

Summary By means of two Burkard Volumetric Spore-Traps situated in the center of Torino and Perugia, pollen was sampled between March and August for three years (1982–83–84). The two pollen spectra, with special reference to trees, were compared for pollen levels and duration of season in the two cities. Comments on vegetation in and around Torino and Perugia and meteorological data are compared with the two pollen spectra.      

Primary production of aquatic macrophytes and their epiphytes in two shallow lakes (Peipsi and Võrtsjärv) in Estonia

In shallow lakes with large littoral zones, epiphytes and submerged macrophytes can make an important contribution to the total annual primary production. We investigated the primary production (PP) of phytoplankton, submerged macrophytes, and their epiphytes, from June to August 2005, in two large shallow lakes. The production of pelagic and littoral phytoplankton and of the dominant submerged macrophytes in the littoral zone (Potamogeton perfoliatus in Lake Peipsi and P. perfoliatus and Myriopyllum spicatum in Lake Võrtsjärv) and of their epiphytes was measured using a modified ¹⁴C method. The total PP of the submerged macrophyte area was similar in both lakes: 12.4 g C m^?2 day^?1 in Peipsi and 12.0 g C m^?2 day^?1 in Võrtsjärv. In Peipsi, 84.2% of this production was accounted for by macrophytes, while the shares of phytoplankton and epiphytes were low (15.6 and 0.16%, respectively). In Võrtsjärv, macrophytes contributed 58%, phytoplankton 41.9% and epiphytes 0.1% of the PP in the submerged macrophyte area. Epiphyte production in both lakes was very low in comparison with that of phytoplankton and macrophytes: 0.01, 5.04, and 6.97 g C m^?2 day^?1, respectively, in Võrtsjärv, and 0.02, 1.93, and 10.5 g C m^?2 day^?1, respectively, in Peipsi. The PP of the littoral area contributed 10% of the total summer PP of Lake Peipsi sensu stricto and 35.5% of the total summer PP of Lake Võrtsjärv.     

Linkages between common wheat yields and climate in Morocco (1982–2008)

In Morocco, wheat production shows a high inter-annual variability due to uncertain rainfall. In view of the importance of this resource to the country’s economy, it is important to gain a better understanding of the natural large-scale climate oscillation governing this variability. In this study, we analyzed de-trended (1) time series of common wheat yields (1983–2008) from 11 agricultural provinces that account for 80 % of national wheat production; (2) monthly rainfall and 10-day temperature from ten meteorological stations; (3) 10-day normalized difference vegetation index (NDVI) from the AVHRR sensor; (4) monthly atmospheric climate indices [North Atlantic Oscillation (NAO) and Scandinavian Pattern (SCA)] and monthly 500 hPa geopotentials fields; and (5) monthly sea surface temperature (SST) fields and indices (NIÑO3, Tropical North Atlantic and Tropical South Atlantic). The relationship between rainfall and temperature during tillering in early winter and grain filling in early spring and wheat yields already observed at the plot scale was also found to be significant at the provincial scale. The linkages between wheat yields and large scale climate have been analyzed for the first time over Morocco. In agreement with previous studies, results show a complex and competing influence of different climate phenomena. The NAO is found to be significantly related to yields during the early stage of wheat growth in December, whereas the SCA correlates with yields later in the season, in January and February. Interesting lagged correlations with higher lead time are also highlighted, with the leading modes of SST variability in the equatorial Atlantic during October (the “Atlantic Niño” mode) and in the North Atlantic (the “Atlantic tripole” mode) in February. Our conclusion is that regional climate indices and variables represent valuable information with which to increase lead time and skill regarding wheat yield predictions in Morocco.     

Distribution and Density of Seals in Pil'tun Bay (Northeastern Sakhalin) in the Summer–Autumn Period

The results of seal counts performed during the summer–autumn period of the years 1999–2001 in Pil'tun Bay from onboard Zodiak motor boats and Mi-8 and Mi-8MTV helicopters have been analyzed. The information is presented on the density of seals in the bay. The heterogeneous distribution pattern of seals in the bay and the presence of intermittent migrations provide favorable conditions for foraging in young animals.     

Distribution of denitrifying bacterial communities in the stratified water column and sediment–water interface in two freshwater lakes and the Baltic Sea

We have studied the distribution and community composition of denitrifying bacteria in the stratified water column and at the sediment–water interface in lakes Plußsee and Schöhsee, and a near-shore site in the Baltic Sea in Germany. Although environmental changes induced by the stratification of the water column in marine environments are known to affect specific populations of denitrifying bacteria, little information is available for stratified freshwater lakes and brackish water. The aim of the present study was to fill this gap and to demonstrate specific distribution patterns of denitrifying bacteria in specific aquatic habitats using two functional markers for the nitrite reductase (nirK and nirS genes) as a proxy for the communities. The leading question to be answered was whether communities containing the genes nirK and nirS have similar, identical, or different distribution patterns, and occupy the same or different ecological niches. The genes nirK and nirS were analyzed by PCR amplification with specific primers followed by terminal restriction fragment length polymorphism (T-RFLP) and by cloning and sequence analysis. Overall, nirS-denitrifiers were more diverse than nirK-denitrifiers. Denitrifying communities in sediments were clearly different from those in the water column in all aquatic systems, regardless of the gene analyzed. A differential distribution of denitrifying assemblages was observed for each particular site. In the Baltic Sea and Lake Plußsee, nirK-denitrifiers were more diverse throughout the water column, while nirS-denitrifiers were more diverse in the sediment. In Lake Schöhsee, nirS-denitrifiers showed high diversity across the whole water body. Habitat-specific clusters of nirS sequences were observed for the freshwater lakes, while nirK sequences from both freshwater lakes and the Baltic Sea were found in common phylogenetic clusters. These results demonstrated differences in the distribution of bacteria containing nirS and those containing nirK indicating that both types of denitrifiers apparently occupy different ecological niches.     

Acidification of lakes in Šumava (Bohemia) and in the High Tatra Mountains (Slovakia)

Acidification of lakes takes place when pH of rainwater is less than 4.5 and the catchments lie on sensitive geology. Both conditions are met for most lakes in Bohemia and Slovakia. Since 1978 we have studied mountain lakes in the Sumava and in the High Tatra Mountains. In Šumava the three lakes under study are of glacial origin. The catchments are small, with steep sides covered by spruce. The bedrocks are biotite-rich paragneiss, together with gneiss, quartzite and granite. In summer 1936 surface pH was 5.7–6.9 in the Lake Čertovo and 6.9–7.0 in the Lake Černé. Now the pH values are 4.3–4.8 in the two lakes and in the Lake Prášilské as well. Old reports on zooplankton are from the years 1871, 1892–96, 1935–37, 1947 and 1960. Since 1979 we have not found any planktonic Crustacea in the lakes Černé and Čertovo. Lake Prášilské is inhabited by Daphnia longispina and Cyclops abyssorum. In July 1989 the pH values were 4.4, 4.7 and 4.7, concentrations of labile monomeric Al were 0.83, 0.68 and 0.24 mg l^-1 in the lakes Čertovo, Černé and Prašilské, respectively. High levels of toxic Al compounds might be responsible for the extinction of planktonic Crustacea in the lakes Čertovo and Černé. All the three lakes are void of fish at present. In the High Tatra Mts. we examined more than 40 lakes above timberline in altitudes 1612–2145 m. They are all clearwater, naturally fishless lakes. The bedrock is granite. Owing to different levels of calcium the lakes are now in different stages of acidification. According to recent changes in the zooplankton they can be divided into three groups: (1) Species composition of planktonic Crustacea has not changed. (2) Planktonic Crustacea were present until 1973 but are absent now. (3) From the original species of Crustacea only Chydorus sphaericus is present. The three groups are well separated along the gradients of calcium, ANC and pH. They can be identified with the Henriksen's bicarbonate (our group 1), intermediate (our group 2) and acid (our group 3) lakes. We suppose that in the process of acidification the lakes of the group (2) have been shifted from oligotrophy to ultraoligotrophy.     

Effect of fluctuations in water level on phytoplankton development in three lakes of the Paraná river floodplain (Argentina)

The effect of fluctuations in water level on phytoplankton development (abundance, biomass, size structure, taxonomic composition, species diversity and rate of community compositional change) in three vegetated lakes of the Paraná River floodplain (27° 27′?S; 58° 55′?W) were studied. Between September 1995 and June 1996 there were two inputs of lotic water. Ordering of physical and chemical parameters (Principal Component Analysis) allowed the differentiation of two phases: I) without lotic influence (limnophase) and II) with lotic influence (potamophase). Two-hundred fifty-eight algal taxa were identified, of which Euglenophyceae showed the highest number of taxa (65% of total). Small Chlorophyceae and Cryptophyceae (C-strategists) predominated in density in both periods. During potamophase, the input of nutrients from a flood event produced an increase in algal biomass and a shift in phytoplankton composition from a Chlorophyceae (C-strategists), to a Cyanophyceae and Euglenophyceae (S-strategists), dominated comunity. Bacillariophyceae, Chrysophyceae, Dinophyceae and Xanthophyceae were best represented during limnophase. All phytoplankton attributes showed significant differences between phases (limnophase vs potamophase) but not among lakes. These results support the hypothesis that hydrology (floods) clearly exerts an overall impact on the phytoplankton community composition in lakes of the Paraná River floodplain. Hydrology effects the lake water chemistry, conditioned by the isolation time prior to a flood, the horizontal dragging and exchange of algae during floods, and the water residence time and aquatic vegetation coverage.     

Climate–water quality relationships in three Western Victorian (Australia) lakes 1984–2000

To achieve robust simulations of past and future climate and their effect on aquatic biota, it is desirable to integrate results from palaeolimnology, contemporary monitoring and process modelling. Here we analyse over 15 years of water quality monitoring data from three lakes, Purrumbete, Colac and Bullen Merri from Western Victoria, Australia and their relationship to climate. In the context of a large number of limnological and palaeoenvironmental studies from the region, we seek to refine understanding of the primary forcing mechanisms that explain present, past and potentially future water quality variability in the lakes. Our analysis shows that there are strong relationships between climate and water quality in these lakes of varied size and salinity (average conductivity range 740–14,000 μS cm⁻¹). The strongest climate–water quality relationship exists between air and water temperature, particular during the colder months. Strong relationships also exist with air temperature and other parameters, most notably nutrient concentrations. Effective precipitation also appears to exert a strong influence on water quality in these lakes. This influence is, by contrast with the influence of air temperature, less direct. Nevertheless, these lakes of varying salt concentration exhibit a coherent pattern of conductivity response to variation in effective precipitation, particularly during times of high moisture stress.     

The human T-cell receptor β-chain repertoire: longitudinal fluctuations and assessment in MHC matched populations

The influence of the environment and of the major histocompatibility complex (MHC) in shaping the human T-cell receptor -chain variable region (TCRBV) repertoire has not been systematically studied. Here, expression of TCRBV gene families was estimated by a sensitive polymerase chain reaction (PCR)-based method. Serial studies of peripheral blood, performed at 2-week intervals over a 3-month period, revealed that fluctuation in the expression of many TCRBV genes occurred in healthy individuals and in the absence of clinically evident infections. Fluctuation of TCRBV4, TCRBV5.2, TCRBV9, and TCRBV13.1 genes were present in all subjects. Additional TCRBV genes fluctuated in some but not in other individuals. Comparison of the TCRBV repertoire between these unrelated individuals indicated differences in the mean expression of TCRBV5.1, TCRBV9, TCRBV11, TCRBV15, TCRBV17, and TCRBV20 genes. For any TCRBV gene, intersubject differences were generally of a magnitude of twofold or less. Larger differences characterized the TCRBV repertoire of CD4 compared to CD8 cells. Some differences, for example over-representation of TCRBV2 and TCRBV5.1 on CD4, and TCRBV10, TCRBV14, and TCRBV16 on CD8 cells, were present in most subjects. Individuals homozygous for DR2- or DR3-bearing extended MHC haplotypes displayed similar individual variability of TCRBV expression. These data indicate that the circulating TCRBV repertoire in humans is both dynamic and diverse. Both environment and MHC effects contribute to the diversity of TCRBV expression.     

Seasonal variations of pollution biomarkers in two populations of Corbicula fluminea (Müller)

Seasonal variations of pollution biomarkers have been studied in two populations of Corbicula fluminea (Müller) for 2 years. Clams were collected from the Sanguinet lake and the Dronne river (Southwest France), sites characterised by water of excellent and passable quality, respectively. Biological parameters studied were enzymatic activity (catalase, propionylcholinesterase, glutathione S-transferase, NADPH-cytochrome c reductase and NADH-cytochrome c reductase activities) and indicators of physiological (protein, carbohydrate, lipid and ash contents, fresh and dry tissue weights, condition factor) and reproductive (amount of oocytes present in gonads and clams incubating larvae in gills) status. Environmental parameters (e.g. water temperature, chlorophyll a concentration) were also monitored. Effects of site, sampling date and season (from spring to winter) were studied, as well as relationships between abiotic and biotic factors. Finally, an index of variability was calculated for each biomarker. Catalase, propionylcholinesterase, NADH-cytochrome c reductase and lipids experienced the most pronounced seasonal fluctuations, whereas glutathione S-transferase, NADPH-cytochrome c reductase and proteins suffered less pronounced ones. For some parameters, results differed depending on the site. Most seasonal changes were related to the reproductive cycle and/or water temperature. Implications of such variations in the use of pollution biomarkers in environmental surveys are discussed.     

Two newly identified mutations (Thr233Ile and Leu152Met) in partially adenosine deaminase-deficient (ADA–) individuals that result in differing biochemical and metabolic phenotypes

Deficiency of adenosine deaminase (ADA^–) results in autosomal recessive immunodeficiency disease of varying severity. Partial ADA^– [ADA deficiency in erythrocytes (RBCs) but substantial ADA in non-RBCs] has also been identified, primarily by population screening of healthy adults in Africa and newborns in New York State. Normal immune function and/or minimal elevations of toxic metabolites in childhood suggested that partial ADA deficiency was benign and therefore that six mutations identified in partially ADA-deficient newborns and expressing 8–80% of normal ADA in non-RBCs were not pathogenic. However, the lowest activity mutation (Arg211Cys) has now been reported in patients with adult-onset immunodeficiency. We have now molecularly and biochemically studied two additional individuals whom we found to represent opposite ends of the spectrum of partial ADA deficiency as to biochemical abnormalities and age of ascertainment. Homozygosity for a newly identified Leu152Met mutation expressing considerably less activity than the pathogenic Arg211Cys mutation was found in a currently healthy 10-year-old Afghanistani child (ascertained at birth). He had the highest accumulation of the metabolite dATP among 13 partially ADA-deficient patients studied, but considerably lower than in those with immunodeficiency. Homozygosity for a newly identified Thr233Ile mutation expressing somewhat greater ADA activity than Arg211Cys was found in a healthy young adult Kung individual, associated with very low metabolite concentrations. Biochemical findings and a family history suggestive of immunodeficiency in prior offspring support the idea that the Leu152Met mutation could result in disease in homozygous individuals challenged by severe environmental insult or in heterozygosity with a null mutation. The pathogenicity of the Thr233Ile mutation, as well as a previously described Ala215Thr mutation with relatively lower activity is less likely but will only be determined by long-term observation of individuals carrying these mutations. Although, in contrast to other partial mutations, neither of these two mutations are at CpG hot spots, the frequency of CpG mutations remains high for partial mutations but is also similarly high in ADA^– immunodeficient patients (5/8 vs 12/21). Received: 7 August 1996 / Accepted: 29 November 1996     

Zooplankton–phytoplankton relationships in shallow subtropical versus temperate lakes Apopka (Florida,USA) and Trasimeno (Umbria,Italy)

This study compares and contrasts the dynamics of phytoplankton, zooplankton, and nutrients in two of the largest shallow lakes in the USA (Lake Apopka, Florida) and Europe (Lago Trasimeno, Umbria, Italy) and considers particularly the biomass ratio of zooplankton to phytoplankton (BZ:BP) in relation to nutrient levels and in the context of data from other subtropical and temperate lakes. Lake Apopka is hypereutrophic with higher concentrations of total phosphorus (TP), nitrogen (TN), and nearly an order of magnitude higher BP than Lago Trasimeno. However, combined data from the two lakes can be fit to a single log–log regression model that explains 72% of the variability in BP based on TP. In contrast, BZ has a significant positive log–log relationship with TP only for Lago Trasimeno, and is much lower than expected based on the TP concentrations observed in Lake Apopka. Lake Apopka has a fish assemblage that includes high densities of gizzard shad (Dorosoma cepedianum) and threadfin shad (D. petenense), similar to other eutrophic Florida lakes that also have extreme low BZ. The ratio BZ:BP is below 0.01 in Lake Apopka, 10-fold lower than in Trasimeno and among the lowest values reported in the literature. Although stress of high water temperature and a greater proportion of inedible cyanobacteria may be contributing factors, the collective results support an emerging view that fish predation limits the biomass of crustacean zooplankton in subtropical lakes. Handling editor: S. I. Dodson     

Phenotypic plasticity of abdomen pigmentation in two geographic populations of Drosophila melanogaster: male–female comparison and sexual dimorphism

In Drosophila melanogaster male, the last abdominal tergites (A5–A6) are completely dark due to a strong internal constraint while, in female, all abdominal tergites (A2–A7) are phenotypically variable and highly plastic. Male A2–A4 are quite similar to those of female, but their plasticity was never investigated. In this paper, we compared the phenotypic plasticity of A2–A4 in both sexes in order to know if the major dimorphism (SD) expressed in male A5–A6 also extended toward the more anterior segments. We also compared two geographic populations living under very different climates in order to know if adaptive differences, previously observed in females also existed in males. With an isofemale line design, pigmentation variation according to growth temperature was investigated in the two populations from France and India. Male and female data were compared and sexual dimorphism (SD) analyzed in various ways. Reaction norms were quite similar in both sexes for A2 and A3, but clearly different for A4. Considering the total pigmentation (A2 + A3 + A4) males were darker than females at low temperatures and either identical to them (France) or lighter (India) above 25°C. SD (male–female difference) was genetically variable among lines and significantly different among segments. Reaction norms of SD exhibited an overall decrease with temperature and also a significant difference among populations, suggesting a local adaptation of SD to thermal conditions. The three plastic segments in male (A2–A4) seem to react adaptively to the thermal environment more efficiently than the same segments in female, in agreement with the thermal budget hypothesis. To our knowledge, it is the first time that a SD trait exhibits an adaptive difference between geographic populations.     

Species composition and seasonal abundance of zooplankton in two Ethiopian Rift Valley lakes — Lakes Abiata and Langano

The composition and annual cycle of the zooplankton of two Ethiopian Rift Valley soda lakes is described. Lake Langano has a conductivity of 1 400 to 1800 µS cm^–1 and a permanent mineral turbidity. Lake Abiata is more concentrated (conductivity 19 000 to 23 000 µS cm^–1) and more alkaline but less turbid; it is characterised by dense phytoplankton blooms, mainly cyanophytes.The zooplankton assemblage is typically tropical, with relatively few species of Cladocera and Copepoda. There was a marked difference in zooplankton between the two lakes, Lake Abiata showing much higher concentrations and greater wet season/ dry season differences. The species composition was also different. Lake Abiata lacked Cladocera, and calanoid copepods occurred only during the wet season with lower conductivities. These two phenomena were attributed to high sodium bicarbonate concentration and to dense cyanophyte blooms. Eleven species of rotifers occurred in Lake Abiata, including six Brachionus spp. but B. rubens was the only rotifer found in Lake Langano. The seasonal variation of the zooplankton is discussed in relation to seasonal fluctuations in conductivity and Chl a concentration.     

Effects of Al on nitrogen (NH 4 + and NO 3 − ) uptake,nitrate reductase activity and proton release in two sorghum cultivars differing in Al tolerance

After growth for 17 to 36 days on nutrient solutions with NH₄NO₃ as nitrogen source (pH 4.2) dry matter of sorghum genotype SC0283 was much less affected by Al (1.5 and 3.0 ppm) than that of genotype NB9040. In the absence of Al both cultivars released protons into the nutrient solution as a result of an excess of cationic nutrients taken up. When Al was present, this proton efflux per unit dry weight increased drastically, especially with the sensitive genotype NB9040. Chemical analysis of plant material and continuous analyses of NO ₃ ⁻ and NH ₄ ⁺ in the nutrient solution indicated, that the Al-induced shift in H⁺-balance of both genotypes could almost completely be attributed to a decreased NO ₃ ⁻ /NH ₄ ⁺ uptake ratio. In vivo nitrate reductase activity (NRA) was reduced in the shoot of NB9040 and to a lesser degree in SC0283. Al-induced decrease in NRA was accompanied by similar percentual decreases in NO ₃ ⁻ tissue concentrations. Therefore this decrease is interpreted as being indirect,i.e., the consequence of the reduced NO ₃ ⁻ uptake of the plants. A direct repression of NRA by Al seems also unlikely because nitrate reductase activity of the roots (where cellular Al-concentrations should be higher than in shoots) was not affected in Al-treated plants of either genotype.     

Feeding and intoxication–detoxification dynamics in two populations of the mussel Mytilus chilensis (Hupé, 1854) with different histories of exposure to paralytic shellfish poisoning (PSP)

Individuals of Mytilus chilensis with different histories of exposure to paralytic shellfish poisoning (PSP) were exposed to a diet containing the dinoflagellate Alexandrium catenella. Feeding and intoxication–detoxification dynamics were evaluated over a period of 12–16?days. Feeding activity was reduced during the first days of exposure, followed by a period of recovery from day 5 to the end of the experiment. Mussels from Corral population (no history of PSP exposure) exceeded the concentration of 80?μg STX eq. 100?g^?1 tissue, although filtration activity was significantly lower compared with individuals from Melinka (frequent PSP exposure). The higher feeding activity and the lower degree of toxin accumulation in the Melinka population appear be associated with frequent exposure to PSP in the natural environment. The use of A. catenella as food resource and the capacity of a rapid intoxication of both populations showed that M. chilensis is an adequate indicator for early detection of PSP.     

Population fluctuations of chironomid and simuliid Diptera at Myvatn in 1977–1996

Aquatic dipterans dominate the macrozoobenthos of Lake Myvatn and the River Laxá and are important in the food web. As benthic sampling is time-consuming and expensive, a window trap was developed in order to facilitate the monitoring of the zoobenthos resource. Four window traps were operated at Myvatn and Laxá during 1977–1996. The results yielded population indices for about 20 species of chironomids and one simuliid. Numbers of the most abundant midge species showed close correlations between 2 trap sites on the lake shore, 5 km apart; Cricotopus tibialis did not show such synchrony. At the River Laxá, the dominant blackfly (Simulium vittatum) showed correlation between 2 trap sites, at the outlet and 3 km downstream; while the chironomids, apart from Micropsectra atrofasciata, did not. The dominant midge of Lake Myvatn, Tanytarsus gracilentus showed 3 cyclic oscillations during the 20-year period. The fluctuations were tracked by Micropsectra lindrothi, Procladius islandicus, Orthocladius consobrinus, Psectrocladius barbimanus and Chironomus islandicus. A group of non-cyclic species included Cricotopus sylvestris and Orthocladius oblidens.     

Variation in Ambrosia pollen concentration in Southern and Central Poland in 1982–1999

The aim of the study was to investigate theAmbrosia pollen concentrations inselected Polish cities and for Kraków torelate it to some meteorological factors.Sampling was carried out in Kraków in1982–1997 and in Rabka in 1992–1996 with theuse of the gravimetric method. In Zakopane,Kraków, Ostrowiec witokrzyski,Warszawa and Pozna in 1995–1996 both thegravimetric and volumetric methods (Burkardtrap) were employed. In Kraków themonitoring has been performed since 1994 usingthe volumetric method. The results show theragweed pollen presence in August and Septemberwith the tendency to appear more frequently inAugust in some years. In Kraków (1994–1999)Ambrosia pollen was found either in thelast two weeks of August or in the first twoweeks of September which seems to be a regularand repeatable pattern every two years.Seasonal fluctuations of Ambrosia pollenconcentration do not show a clear increasingtendency except at Warszawa and Ostrowiecwitokrzyski in 1996 and at Krakówin 1999. Percentage of Ambrosia pollen inannual sums of total pollen is very low anddoes not exceed 1% except at Ostrowiecwitokrzyski in 1996 (1.2%) and atKraków in 1999 (2%). For Kraków theanalysis of some meteorological factors (Tmax,Tmin, precipitation, wind direction) wasperformed. High temperature and lack of rain orlow precipitation correlate well with ragweedpollen concentrations. During the Ambrosia pollen seasons ESE, E, S, SE, WSW, SWwind directions prevailed which could suggest along-distance transport from Ukraine, the CzechRepublic, Slovakia and also from Hungary, one ofthe most ragweed-polluted countries.