Three types of epidermal cultures of fish were used for toxicological investigations, a primary cell culture and a tissue culture prepared from the rainbow trout <i>Oncorhynchus mykiss</i> Walbaum and the cell line EPC, derived from a skin tumour of the carp <i>Cyprinus carpio</i> L. Two studies were carried out to compare the different culture systems. In the first cultures were incubated with nonylphenol and in the second set of experiments the cell cultures were exposed to a wastewater sample containing low concentrations of nonylphenol (NP). Both cell cultures were similarly sensitive to nonylphenol with respect to the endpoints cell viability (LC₅₀ (24 h) 47.1 μM NP (primary cell culture) and 44.2 μM NP (EPC)) values and apoptotic rate (significantly increased apoptotic rate after exposure to 50 μM NP for 24 h, <i>p</i> < 0.001 (primary cell culture), <i>p</i> = 0.008 (EPC)). The explant culture was slightly less sensitive (increased apoptotic rate after exposure to 50 μM NP for 24 h, but not significant: <i>p</i> = 0.385), which could be due to the capabilities of a differentiated tissue, providing more protective repair mechanisms, compared with single cells. All cultures revealed a concentration–response relationship for the endpoint apoptotic rate after the application of nonylphenol for 24 h. After wastewater exposure, a significant decrease in the apoptotic rate was measured in the primary cell culture (dilution wastewater : medium 1:1:<i>p</i> = 0.018; dilution wastewater : medium 1:2:<i>p</i> = 0.003), whereas the cell line EPC did not reveal any effects. Our results show that the endpoint apoptotic rate is more sensitive than the parameter cell viability for detecting adverse effects of a wastewater sample.

Most environments periodically impose severe stress that may cause high mortality and alter population structure, for example, by removing sick and old individuals. We examined how anoxic conditions and starvation of the host affect virulence of two closely related trematode parasites, <I>Rhipidocotyle campanula</I> and <I>R. fennica</I>. These parasites differ by prevalence of infection and by exploitation rate of individual hosts (freshwater clam, <I>Anodonta piscinalis</I>). Infection by <I>R. campanula</I> is rare (<5% prevalence of infection) and destroys on average 90% of the gonad tissue of the individual host. Infection by <I>R. fennica</I> is more common (20–60% prevalence of infection) and leads to on average 30% gonad destruction. In the end, both infections lead to host infertility. We predicted that <I>R. campanula</I> induces higher host mortality than <I>R. fennica</I> under host stress. In two laboratory experiments, we exposed naturally-infected and uninfected clams to anoxia and to starvation. Anoxia occasionally takes place during winter in eutrophic lakes, while some degree of starvation should occur seasonally. We found that mortality rate of clams was much higher under anoxia than under starvation, and that infection increased mortality rate under both types of host stress. As predicted, <I>R. campanula</I> induced higher host mortality than <I>R. fennica</I>. Host survival was population-specific, suggesting that clams of different origins carried different amount of energy reserves. Severe environmental perturbation may remove <I>R. campanula</I> infected individuals from the host population, but recolonization from the fish host is likely to prevent extinction of the parasite suprapopulation. The observed high host mortality induced by <I>R. campanula</I> may be one ecological explanation for the consistently lower prevalence of infection of <I>R. campanula</I> when compared to <I>R. fennica</I>.

The behavior, morphology and response to stimuli in biological systems are dictated by the interactions between their components. These interactions, as we observe them now, are therefore shaped by genetic variations and selective pressure. Similar to what has been achieved by comparing genome structures and protein sequences, we hope to obtain valuable information about systems' evolution by comparing the organization of interaction networks and by analyzing their variation and conservation. Equally, significantly we can learn whether and how to extend the network information obtained experimentally in well-characterized model systems to different organisms. We conclude from our analysis that, despite the recent completion of several high throughput experiments aimed at the description of complete interactomes, the available interaction information is not yet of sufficient coverage and quality to draw any biologically meaningful conclusion from the comparison of different interactomes. Thus, the transfer of network information obtained from simple organism to evolutionary distant species should be carried out and considered with caution. By using smaller higher-confidence datasets, a larger fraction of interactions is shown to be conserved; this suggests that with the development of more accurate experimental and informatic approaches, we will soon be in the position to study the network evolution.

The effects of elevated pCO₂ on net ecosystem CO₂ exchange were investigated in managed Lolium perenne (perennial ryegrass) and Trifolium repens (white clover) monocultures that had been exposed continuously to elevated pCO₂ (60 Pa) for nine growing seasons using Free Air CO₂ Enrichment (FACE) technology. Two levels of nitrogen (N) fertilization were applied. Midday net ecosystem CO₂ exchange (mNEE) and night-time ecosystem respiration (NER) were measured in three growing seasons using an open-flow chamber system. The annual net ecosystem carbon (C) input resulting from the net CO₂ fluxes was estimated for one growing season. In both monocultures and at both levels of N supply, elevated pCO₂ stimulated mNEE by up to 32%, the exact amount depending on intercepted PAR The response of mNEE to elevated pCO₂ was larger than that of harvestable biomass. Elevated pCO₂ increased NER by up to 39% in both species at both levels of N supply. NER, which was affected by mNEE of the preceding day, was higher in T. repens than in L. perenne. High N increased NER compared to low N supply. According to treatment, the annual net ecosystem C input ranged between 210 and 631 g C m^-2 year ^-1 and was not significantly affected by the level of pCO₂. Low N supply led to a higher net C input than high N supply. We demonstrated that at the ecosystem level, there was a long-term stimulation in the net C assimilation during daytime by elevated pCO₂. However, because NER was also stimulated, net ecosystem C input was not significantly increased at elevated pCO₂. The annual net ecosystem C input was primarily affected by the amount of N supplied.

Effects of different combinations of stressors (viz. temperature, food level) on growth, developmental and survival rates of <I>Rana temporaria</I> tadpoles from two geographically widely (≈ 1500 km) separated populations were studied in a common garden experiment. In both populations, low temperature and low food level lead to towered growth rates and delayed metamorphosis, whereas high temperature and high food level had the opposite effect. Tadpoles from north metamorphosed earlier and exhibited higher growth rates than tadpoles from south, suggesting local adaptation to shorter growth period and cooler ambient temperature in north. Size at metamorphosis did not differ between the two populations, but when the differences in metamorphic age were accounted for, then the tadpoles from north were larger than those from south. These results suggest considerable adaptive genetic differentiation in growth rates, size and timing of metamorphosis between northern and southern <I>R. temporaria</I> populations. In both populations, high food levels tended to reduce tadpole survival rates and there was a negative correlation between growth and survival rates across different treatments in both populations. In general, tadpoles from north experienced high mortality rates in high food level - low temperature treatments, whereas southern tadpoles experienced high mortality in high food level-high temperature treatments. This suggest that there may be genetic differences among different populations as how they would be influenced by high nutrient loads, such as brought along for example by fertilization of forest or agricultural soils.

Euthrophication-associated changes in the physical and biological environment of lakes and ponds are potentially a source of major stress for many aquatic organisms. In Scandinavia, the nitrate concentrations in lakes and ponds decrease towards north due to a naturally lower productivity of the habitats, but also due to lower supplementation of anthropogenic nitrogen. A chronic experiment using ecologically relevant concentrations of sodium nitrate (0–5000 μ gl^-1) was used to test whether common frog (<em>Rana temporaria</em> L<em>.</em>) larvae from northern parts of Scandinavia are less well adapted to cope with high nitrate concentrations than those from the southern parts. Slight, but significant differences in nitrate tolerance, as measured in terms of growth rate and size at metamorphosis, between the two regions were found. High concentrations of nitrate reduced the growth rates and metamorphic size in north, but not in south. However, there was no clear-cut impact of high nitrate concentrations on developmental rate or on mortality until metamorphosis. The general lack of large effects of nitrate treatment on the response variables suggests that nitrates per se do not pose any significant threat to the development of <em>R. temporaria</em> tadpoles under a natural range of concentrations. This was confirmed in an acute test where results suggest that ammonia and nitrite, compounds seldom found in high concentrations in Fennoscandian lakes, are possibly responsible for the larger negative effects of ‘nitrate’ observed in previous studies of amphibians.

1. Conditions experienced during the early stages of development may have carry-over effects on performance during later life. The egg laying period and embryonic development of temperate and boreal zone amphibians often coincides with peak acidity resulting from spring snow-melt, but the effects of acid conditions during embryonic stage on subsequent performance are unknown.<br/> 2. We investigated the potential carry-over effects of acidity during the embryonic stage on performance up to metamorphosis in the common frog (<I>Rana temporaria</I>) tadpoles. There were four combinations of acid (4.5) and neutral (7.5) pH treatments applied to the egg and larval stages in a factorial laboratory experiment. In addition, we studied the difference in embryonic and larval tolerance of acidity between two populations originating from circumneutral (pH 6.6) and acidic conditions (pH 4.8).<br/> 3. The effects of acid conditions during the embryonic stage were sublethal, as indicated by delayed development and reduced size. Under acid conditions, tadpoles that had been raised in neutral water as embryos at first grew more slowly than tadpoles raised under acid conditions as embryos. At metamorphosis, no effects of embryonic acidity were detectable indicating that tadpoles were able to compensate fully for the initial reduction in growth.<br/> 4. Acid conditions during the larval period had a strongly negative effect on survival, size and age at metamorphosis. The amount of food consumed was lower under acid conditions, suggesting that reduced food consumption was at least partly responsible for the negative effects.<br/> 5. Although the two populations differed in the length of larval period, there was no indication of a differential response to the treatments in any of the metamorphic traits studied.<br/> 6. These results suggest that, although moderate acid conditions during embryonic development affect growth and development negatively, this influence does not persist after conditions have returned to normal. However, even moderately acid conditions during the larval period may have a strong negative influence on survival and performance of the tadpoles.

Although the negative effects of ultraviolet-B (UV-B) radiation on the development of many amphibian species have been demonstrated, some species—such as the common frog (<I>Rana temporaria</I>)—seem to be tolerant of UV-B radiation. The amount of UV-B radiation received is likely to vary among populations of the same species, but little is known about geographic variation in UV-B tolerance. Similarly, although UV-B radiation can have synergistic effects with other stressors, no studies have focused on geographic variation of these effects on amphibians. We investigated the synergistic effects of UV-B radiation and low pH on hatchability and early development of <I>R. temporaria</I> embryos in a factorial laboratory experiment with animals originating from southern and northern Sweden. Newly fertilized eggs were exposed to three different UV-B treatments (no UV-B [control], 1.254 k/J/m<SUP>2</SUP> [normal] and 1.584 k/J/m<SUP>2</SUP> [26% enhanced]) and two pH treatments (4.5 [low] and 7.6 [neutral]). Ultraviolet-B radiation in combination with low pH lead to markedly (approximately 50%) reduced survival rates and increased (approximately 30%) frequency of developmental anomalies in the northern but not in the southern population. The UV-B-exposed embryos hatched at smaller size in the southern population, whereas low pH reduced hatchling size in both populations. In both populations and pH treatments, embryos in the normal UV-B treatment developed significantly faster than embryos in the enhanced or control UV-B treatments. No interaction between pH and UV-B on developmental rates or hatchling size was detected. The results demonstrate—contrary to earlier belief—that <I>R. temporaria</I> embryos are not insensitive to increased levels of UV-B radiation. The lethal effects of UV-B radiation may, however, become manifested only in combination with other stressors, such as low pH, and the effects of this synergism may differ among different populations of the same species.

Spatially varying directional selection together with restricted gene flow among populations is expected to lead to local adaptation. One environmental factor that potentially causes strong directional selection, but is little explored in evolutionary terms, is naturally and anthropogenically induced acidity. We studied local adaptation to acidity in four Swedish populations (two originating from areas that have suffered from severe anthropogenic acidification during the 1900s and two from areas which have remained neutral due to higher buffering capacity) of the moor frog <I>Rana arvalis</I> in a laboratory experiment by investigating whether differences in acid tolerance correspond to population origin. Embryos were raised from fertilization to hatching at three different pH levels (pH 4.0, 4.25 and 7.5), corresponding to levels experienced by these populations in nature, and acid stress tolerance was measured in terms of embryonic survival, hatchling size, and age. Evidence for local adaptation in all of these traits was found, the acid origin embryos having higher survival and less impaired growth performance under acid conditions than the neutral origin embryos. Our estimated rates of divergence (0.007-0.102 haldanes) suggest a rapid adaptation process in response to anthropogenic environmental change, and that the different traits have evolved at relatively similar rates.

Adaptive genetic differentiation along a climatic gradient as a response to natural selection is not necessarily expressed at phenotypic level if environmental effects on population mean phenotypes oppose the genotypic effects. This form of cryptic evolution – called countergradient variation – has seldom been explicitly demonstrated for terrestrial vertebrates. We investigated the patterns of phenotypic and genotypic differentiation in developmental rates of common frogs (<I>Rana temporaria</I>) along a ca. 1600 km latitudinal gradient across Scandinavia. Developmental rates in the field were not latitudinally ordered, but displayed large variation even among different ponds within a given latitudinal area. In contrast, development rates assessed in the laboratory increased strongly and linearly with increasing latitude, suggesting a genetic capacity for faster development in the northern than the southern larvae. Experiments further revealed that environmental effects (temperature and food) could easily override the genetic effects on developmental rates, providing a possible mechanistic explanation as to why the genetic differentiation was not seen in the samples collected from the wild. Our results suggest that the higher developmental rates of the northern larvae are likely to be related to selection stemming from seasonal time constrains, rather than from selection dictated by low ambient temperatures <I>per se</I>. All in all, the results provide a demonstration of environmental effects concealing substantial latitudinally ordered genetic differentiation understandable in terms of adaptation to clinal variation in time constrains.

Given sufficient time and genetic variation, populations of ectothermic animals living in different thermal environments are expected to diverge in their thermal optima for growth. Several recent studies have used common frog (<I>Rana temporaria</I>) tadpoles as models to study animal adaptation to geographic variation in ambient temperatures, but little attention has been paid to how the growth of different body parts responds to variation in temperature. We examined the variation in early growth in body. tail and relative tail length of common frog tadpoles in a common garden experiment that subjected individuals from six populations situated along a 1600-km latitudinal gradient to different temperature and food treatments. We found a high degree of latitudinally unordered inter-populational differentiation in relative tail length, and that increasing levels of environmental stress (low temperature and restricted food) lead to increased mean relative tail length. This occurred mainly because of changes in body growth, not because of changes in tail growth <I>per se</I>. This suggests that growth of the tail itself is less sensitive to environmental stress than body growth, but at the same time the relative length of tail can be a good indicator of growth conditions experienced by individuals. In general, the results do not support the earlier proposition that common frog tadpoles in the south have relatively longer tails due to increased risk of predation, but indirect evidence was found to support the contention that the populations along the latitudinal gradient have different thermal optima for growth as indicated by latitudinally ordered differences in how relative tail length changed in response to temperature treatments.

<I>Sphingomonas</I> sp. strain TTNP3 degrades 4(3',5'-dimethyl-3'-heptyl)-phenol and unidentified metabolites that were described previously. The chromatographic analyses of the synthesized reference compound and the metabolites led to their identification as 2(3',5'-dimethyl-3'-heptyl)-1,4-benzenediol. This finding indicates that the nonylphenol metabolism of this bacterium involves unconventional degradation pathways where an NIH shift mechanism occurs.

The aerobic degradation of the natural hormone 17-β-estradiol (E2) and the synthetic hormone 17-α-ethinyl estradiol (EE2) was investigated in batch experiments with activated sludge from a conventional and a membrane sewage treatment plant. E2 was converted to estrone (E1), the well known metabolite, and further completely transformed within 3 days. The turnover rates of E2 did not differ greatly between conventional and membrane activated sludge. EE2 was persistent in both sludges. By several transfers into fresh E2-medium an enrichment culture could be selected that used E2 as growth substrate. Further enrichment and isolation led to a defined mixed culture consisting of two strains, which were identified by a polyphasic approach as <I>Achromobacter xylosoxidans</I> and <I>Ralstonia</I> sp., respectively. The culture used E2 and E1 as growth substrates and transformed estriol (E3) and 16-α-hydroxyestrone but not the xenoestrogens bisphenol A, α-zearalenol, mestranol or EE2. The turnover rates of E2 were 0.025–0.1 μg h^-1 cfu^-1 and did not depend on the steroid concentration.

For monitoring groundwater at tar oil contaminated sites a simple method of analysis was developed for the simultaneous detection of several NSO heterocyclic compounds, homocyclic compounds, mobile two- and three-cyclic PAHs and selected metabolites. The groundwater samples are enriched using SPE with polymer material at pH 4. Chromatographic separation and detection is performed by LC with diode array UV or fluorescence detection. The recoveries of 25 selected compounds were mostly between 80-110% and the detection limits were 0.4-2.4 μg/L for UV detection and for the fluorescence detectable compounds 0.4-140 ng/L. The method was successfully applied to groundwater samples from a wood preserving facility. Especially benzo(<I>b</I>)thiophene showed an increasing dominance downgradient of the source. Detection of metabolites, such as 1-hydroxyiso-, 2-hydroxyquinoline and 2-hydroxy-4-methylquinoline, 2-naphthoic acid, and 1-indanone, indicating in situ biodegradation, was confirmed by LC-ESI-MS analysis.

Human metabolism of the monoterpene cyclic ether 1,8-cineole was investigated in vitro and in vivo. In vitro, the biotransformation of 1,8-cineole was investigated by human liver microsomes and by recombinant cytochrome P450 enzymes coexpressed with human CYP-reductase in Escherichia coli cells. Besides the already described metabolite 2α-hydroxy-1,8-cineole we found another metabolite produced at high rates. The structure was identified by a comparison of its mass spectrum and retention time with the reference compounds as 3α-hydroxy-1,8-cineole. There was a clear correlation between the concentration of the metabolites, incubation time and enzyme content, respectively. CYP3A4/5 antibody significantly inhibited the 2α- and 3α-hydroxylation catalyzed by pooled human liver microsomes. Further kinetic analysis revealed that the Michaelis-Menten <I>K</I>_m and <I>V</I>_max for oxidation of 1,8-cineole in position three were 19 μM and 64.5 nmol/min/nmol P450 for cytochrome P450 3A4, and 141 μM and 10.9 nmol/min/nmol P450 for cytochrome P450 3A5, respectively. To our knowledge, this is the first time that 3α-hydroxy-1,8-cineole is described as a human metabolite of 1,8-cineole. We confirmed these in vitro results by the investigation of human urine after the oral administration of cold medication containing 1,8-cineole. In human urine we found by GC-MS analysis the described metabolites, 2α-hydroxy-1,8-cineole and 3α-hydroxy-1,8-cineole.

Wastewater reclamation holds promise as an important water resource as the desire to develop arid regions continues to place increasing demands on finite water resources. The debate surrounding the consumption of reclaimed wastewater finds risk managers pondering the question of what types of water quality standards might be set in order to provide the proper level of safety associated with the use of reclaimed wastewater. We propose quality categories for different reuses such as irrigation or indirect aquifer recharge with different requirements towards microbial and chemical parameters. Based on recent existing guidelines and risk estimations, microbial and chemical limits for each category were compiled. Since economic calculations are very important, analytical costs are included and measurements frequency is proposed. Biological parameters have to indicate all potential pathogenic organisms including viruses, bacteria and parasites from different origins. The selected biological indicator parameters most used in rules and regulations are coliforms and <I>E coli</I>, indicating the occurrence of a former faecal contamination and the possible presence of all pathogens occurring in faeces of warm-blooded animals. In the case of wastewater reuse, biological parameters have to indicate all potential pathogens causing infection diseases and/or intoxication in all living beings including plants and animals. The large number of possible chemical parameters in relation with wastewater reclamation and reuse has to be adapted and minimized with respect to the origin of the sewage, the extent of the treatment process and the intended use. These parameters must cover a broad spectrum of toxicological and ecological risks as well as possible technical disorders. Risk assessment and risk management are also necessary.

<I>Sphingomonas</I> sp. strain TTNP3 has been previously described as a bacterium that is capable of degrading the technical mixture of nonylphenol (NP) isomers and also the 4(3',5'-dimethyl-3'-heptyl)-phenol single isomer of NP. Until recently, 3,5-dimethyl-3-heptanol was the only reported metabolite of 4(3',5'-dimethyl-3'-heptyl)-phenol. A short time ago, the detection of an intracellular metabolite resulting from the oxidation of 4(3',5'-dimethyl-3'-heptyl)-phenol which was identified as 2(3,5-dimethyl-3-heptyl)-benzenediol has been reported. A decisive element for this identification was the occurrence of some slight differences with the two most probable metabolites i.e. 4(3',5'-dimethyl-3'-heptyl)-resorcinol and 4(3',5'-dimethyl-3'-heptyl)-catechol. These facts led us to hypothesise some NIH shift mechanisms explaining the formation of 2(3',5'-dimethyl-3'-heptyl)-benzenediol. In the present work, we describe the steps that led to the detection of these metabolites in the intracellular fraction of Sphingomonas sp. strain TTNP3. The formation of analogous intracellular metabolites resulting from the degradation of the technical mixture of NP is reported. To further elucidate these degradation products, studies were carried out with cells grown with 4(3',5'-dimethyl-3'-heptyl)-phenol as sole carbon source. The description of the syntheses of reference compounds, i.e. 4(3',5'-dimethyl-3'-heptyl)-resorcinol and 4(3',5'-dimethyl-3'-heptyl)-catechol and their comparative analyses with the intermediates of the degradation of 4(3',5'-dimethyl-3'-heptyl)-phenol are presented.

This paper reviews the rapidly expanding literature on the ecological effects of cyanobacterial toxins. The study employs a qualitative meta-analysis from the literature examining results from a large number of independent studies and extracts general patterns from the literature or signals contradictions. The meta-analysis is set up by putting together two large tables – embodying a large and representative part of the literature (see Appendix A). The first table (Table A.1) reviews the presence (concentrations) of different cyanobacterial toxins in the tissues of various groups of aquatic biota after exposure via different routes, experimentally in the lab or via natural routes in the environment. The second table (Table A.2) reviews the dose dependent effect of toxins on biota. The great majority of studies deal with the presence and effects of microcystin, especially of the MC-LR congener. Although this may partly be justified – MC-LR is an abundant and highly toxic protein – our review also emphasizes what is known about (i) other MC congeners (a number of studies showed a preferred accumulation of the less toxic variant MC-RR in animal tissues), (ii) nodularin (data on a range of biota from studies on the Baltic Sea), (iii) neurotoxins like anatoxin-a(s), which are conspicuously often present at times when mass mortalities of birds occur, (iv) a few studies on the presence and effects of cylindrospermposin, as well as (v) the first examples of ecological effects of newly identified bioactive compounds, like microviridin-J. Data were reorganized to assess to what extent bioconcentration (uptake and concentration of toxins from the water) or biomagnification (uptake and concentration via the food) of cyanobacterial toxins occurs in ecosystems. There is little support for the occurrence of biomagnification, and this reduces the risk for biota at higher trophic levels. Rather than biomagnification biodilution seems to occur in the foodweb with toxins being subject to degradation and excretion at every level. Nevertheless toxins were present at all tropic levels, indicating that some vectorial transport must take place, and in sufficient quantities for effects to possibly occur. Feeding seemed to be the most important route for exposure of aquatic biota to cyanobacterial toxins. A fair number of studies focus on dissolved toxins, but in those studies purified toxin typically is used, and biota do not appear very sensitive to this form of exposure. More effects are found when crude cyanobacterial cell lysates are used, indicating that there may be synergistic effects between different bioactive compounds. Aquatic biota are by no means defenseless against toxic cyanobacteria. Several studies indicate that those species that are most frequently exposed to toxins in their natural environment are also the most tolerant. Protection includes behavioral mechanisms, detoxication of MC and NODLN by conjugation with glutathione, and fairly rapid depuration and excretion. A common theme in much of the ecological studies is that of modulating factors. Effects are seldom straightforward, but are dependent on factors like the (feeding) condition of the animals, environmental conditions and the history of exposure (acclimation and adaptation to toxic cyanobacteria). This makes it harder to generalize on what is known about ecological effects of cyanobacterial toxins. The paper concludes by summarizing the risks for birds, fish, macroinvertebrates and zooplankton. Although acute (lethal) effects are mentioned in the literature, mass mortalities of – especially – fish are more likely to be the result of multiple stress factors that co-occur during cyanobacterial blooms. Bivalves appear remarkably resistant, whilst the harmful effects of cyanobacteria on zooplankton vary widely and the specific contribution of toxins is hard to evaluate.

Lake Victoria had a fish fauna dominated by 500+ species of haplochromine cichlids that made up more than 80% of the fish mass. The five main trophic groups caught with bottom trawlers in the sub-littoral areas of the Mwanza Gulf were: detritivores, zooplanktivores, insectivores, molluscivores and piscivores. The detritivores (13+ species) formed the most important guild, making up 60-80% of the number of individuals, followed by the zooplanktivores (12+ species), which comprised 10-30%. In the 1980s the haplochromines from the sub-littoral and offshore areas (estimated at some 200 species) vanished almost completely. Commercial trawl fishery, the upsurge of the introduced Nile perch, and an increase of eutrophication were potential causes of this decline. In the 1990s, when Nile perch was heavily fished, a recovery of some haplochromine species was observed. We studied the decline and partial recovery of the different haplochromine trophic groups in the northern part of the Mwanza Gulf. The rate at which the trophic groups declined differed; the relatively large piscivores, insectivores and molluscivores were the first to disappear from the catches. The small detritivores and zooplanktivores declined at lower rates, especially the latter group. From the beginning of the 1990s a resurgence of both groups was observed. By 2001, the zooplanktivores had reached their previous level of abundance, but their diversity declined from more than 12 species to only three. Though four detritivorous species began being regularly caught again, they constituted only about 15% of the number of individuals, while the zooplanktivores made up more than 80%. The patterns of decline and recovery indicate that, though fishery played a role locally, predation by Nile perch and eutrophication were the main factors determining the fate of the haplochromines. However, it has so far been impossible to establish the causal relationship between the two, and the relative impact of each of these phenomena separately. The potential effects of the changed trophic dominance, and the importance of the haplochromines for the ecosystem and a sustainable fishery, are discussed.

The degradation of radiolabeled 4(3′,5′-dimethyl-3′- heptyl)-phenol [nonylphenol (NP)] was tested with resting cells of <I>Sphingomonas</I> sp. strain TTNP3. Concomitantly to the degradation of NP, a metabolite identified as hydroquinone transiently accumulated and short-chain organic acids were then produced at the expense of hydroquinone. Two other radiolabeled isomers of NP, 4(2′, 6′-dimethyl-2′-heptyl)-phenol and 4(3′,6′-dimethyl-3′-heptyl)-phenol, were synthesized. In parallel experiments, the 4(2′,6′-dimethyl-2′-heptyl)-phenol was degraded more slowly than the other isomers of NP by strain TTNP3, possibly because of effects of the side-chain structure on the kinetics of degradation. Alkylbenzenediol and alkoxyphenol derivatives identified as metabolites during previous studies were synthesized and tested as substrates. The derivatives were not degraded, which indicated that the mineralization of NP does not proceed via alkoxyphenol as the principal intermediate. The results obtained led to the elucidation of the degradation pathway of NP isomers with a quaternary α-carbon. The proposed mechanism is a type II <I>ipso</I> substitution, leading to hydroquinone and nonanol as the main metabolites and to the dead-end metabolites alkyl-benzenediol or alkoxyphenol, depending on the substitution at the α-carbon of the carbocationic intermediate formed.

We develop an agent-based model for forest harvesting to study how interactions between neighboring land parcels and the degree of information flow among landowners influence harvesting patterns. We assume a forest is composed of a number of land parcels that are individually managed. Each parcel is either mature forested, just-harvested, or immature forested. The state transition of each parcel is described by a Markov chain that incorporates the successional dynamics of the forest ecosystem and landowners' decisions about harvesting. Landowners decide to cut trees based on the expected discounted utility of forested vs. harvested land. One landowner's decision to cut trees is assumed to cause the degradation of ecosystem services on the downstream forested parcels. We investigated two different scenarios: in a strongly-connected society, landowners are familiar with each other and have full information regarding the behavior of other landowners. In a weakly-connected society, landowners do not communicate and therefore need to make subjective predictions about the behavior of others without adequate information. Regardless of the type of society, we observed that the spatial interaction between management units caused a chain reaction of tree harvesting in the neighborhood even when healthy forested land provided greater utility than harvested land. The harvest rate was higher in a weakly-connected society than that in a strongly-connected society. If landowners employed a long-term perspective, the harvest rate declined, and a more robust forested landscape emerged. Our results highlight the importance of institutional arrangements that encourage a long-term perspective and increased information flow among landowners in order to achieve successful forest management.

Deforestation often has been studied in terms of land-use models, in which natural processes such as ecological succession, physical disturbance and human decision-making are combined. In many land-use models, landowners are assumed to make decisions that maximize their utilities. However, since human understanding of ecological and social dynamics is clouded by uncertainty, landowners may not know true utility values, and may learn these values from their experiences. We develop a decision model for forest use under social learning to explore whether social learning is efficient to improve landowners' decisions and can lead to effective forest management. We assume that a forest is composed of a number of land parcels that are individually managed; landowners choose whether or not to cut trees by comparing the expected utilities of forest conservation and deforestation; landowners learn utility values not only from their own experiences, but also by exchanging and sharing information with others in a society. By analyzing the equilibrium and stability of the landscape dynamics, we observed four possible outcomes: a stationary-forested landscape, a stationary-deforested landscape, an unstable landscape fluctuating near an equilibrium, and a cyclic-forested landscape induced by synchronized deforestation. Synchronized deforestation, which resulted in a resource shortage in a society, was likely to occur when landowners employed a stochastic decision and a short-term memory about past experiences. Social welfare under a cyclic-forested landscape can be significantly lower than that of a stationary-forested landscape. This implies that learning and remembering past experiences are crucial to prevent overexploitation of forest resources and degradation of social welfare.

The effect of group size on the routine metabolic rate and activity of the two shoaling percids, Eurasian perch <I>Perca fluviatilis</I> and ruffe <I>Gymnocephalus cernuus</I>, was studied by using twin-flow intermittent respirometry and time-lapse video techniques. In both species, we found a clear group effect. In isolated fish, oxygen consumption was as much as twice that in groups of eight fish, with intermediate values in groups of four fish. The routine metabolic rate was highest during twilight in both species, irrespective of group size. Eurasian perch consumed more oxygen and were more active during the day than during the night, whereas the oxygen consumption and activity of ruffe were higher during the night than during the day. With increasing group size, the differences between day and night decreased and the diel cycle was less pronounced. Individual fish may benefit from the presence of conspecifics through a calming effect that reduces their energetic costs. We advise that the social behavior of a species be more thoroughly considered when planning behavioral, growth, and respiration experiments. Because bioenergetic model parameters for many species are based on data gained from isolated fish, we conclude that without considering group size the results of bioenergetic modeling may be seriously biased.

Two twin short gravity cores and a long piston core recovered from the deepest part of proglacial Lake Bramant (Grandes Rousses Massif, French Alps), under and overlying a large slump identified by high-resolution seismic profile, allow the investigation of Holocene natural hazards and interactions between human activity and climatic changes at high-altitude. Annual sedimentation throughout the cores (glacial varves) is identified on photographs, ITRAX (high-resolution continuous microfluorescence-X) and CAT-Scan (computerized axial tomography) analyses and is supported by (1) the number of dark and light laminations between dates obtained by radionuclide measurements (<SUP>137</SUP>Cs, <SUP>241</SUP>Am), (2) the correlation of a slump triggered by the nearby AD 1881 Allemond earthquake (MSK intensity VII) and of a turbidite triggered by the AD 1822 Chautagne regional earthquake (MSK intensity VIII), (3) the number of laminations between two accelerator mass spectrometry (AMS) <SUP>14</SUP>C dates, and (4) archaeological data. In Lake Bramant, dark layers are coarser, contain less detrital elements, but more neoformed elements and organic matter content. These darker laminations result from calm background sedimentation, whereas the lighter layers are finer and rich in detrital elements and reflect the summer snowmelt. Traces of mining activity during the Roman civilization apogee (AD 115–330) and during the Early Bronze Age (3770–3870 cal BP) are recorded by lead and copper content in the sediments and probably result from regional and local mining activity in the NW Alps. Warmer climate during the Bronze Age in this part of the Alps is suggested by (1) two organic deposits (4160–3600 cal BP and 3300–2850 cal BP) likely reflecting a lower lake level and smaller glaciers and (2) evidence of a different vegetation cover around 2500 m a.s.l. The onset of clastic proglacial sedimentation between 3600–3300 cal BP and since 2850 cal BP is synchronous with periods of glacier advances documented in the Alps and high-lake levels in west-central Europe. This major change in proglacial sedimentation highlights the development of a larger St. Sorlin glacier in the catchment area of Lake Bramant.

The removal of ammonium ion from wastewater is an important part of tertiary wastewater treatment and is increasingly necessary to meet drinking water and discharge standards being applied in much of the developed world. The use of nitrification filters is an established technology which involves the biological oxidation of ammonium ion to the more benign nitrate ion. An alternative technique for ammonia removal is the use of ion-exchange however the capital costs can be significant and the economics of chemical regeneration may be prohibitive for large volume applications. In this paper we examine the combination of nitrification and ion-exchange in a packed bed system using the natural zeolitic ion-exchangers, clinoptilolite, and mordenite on which colonies of nitrifying bacteria are cultivated. The combined system intensifies ammonia removal and offers the possibility in principle of a more robust technique less sensitive to rapid perturbations in ammonia concentration and less costly than in a single ion-exchange process. One limitation of this approach is the rapid consumption of oxygen in the biologically active column. The paper demonstrates a novel technique for enhancing the oxygen concentration in a combined ion-exchange and nitrification packed column. The performance of fixed beds of clinoptilolite and mordenite in the presence of nitrifying bacteria is compared to that in columns in which only ion-exchange is occurring. Two modes of aeration are compared: (1) external aeration in which the feedwater is aerated conventionally by gas bubbling; (2) in situ aeration in which a membrane-aeration unit is incorporated into the packed bed. The ammonia removal in the presence of the nitrifiers is significantly intensified. Both methods of aeration provided a comparable further enhancement. In the case of the membrane system the air consumption was reduced by a factor of 60.

Gas–water phase transfer associated with the dissolution of trapped gas in porous media is a key process that occurs during pulsed gas sparging operations in contaminated aquifers. Recently, we applied a numerical model that was experimentally validated for abiotic situations, where multi-species kinetic inter-phase mass transfer and dissolved gas transport occurred during pulsed gas penetration–dissolution events [Balcke, G.U., Meenken, S., Hoefer, C. and Oswald, S.E., 2007. Kinetic gas–water transfer and gas accumulation in porous media during pulsed oxygen sparging. Environmental Science & Technology 41(12), 4428–4434]. Here we extend the model by using a reactive term to describe dissolved oxygen demand reactions via the formation of a reaction product, and to study the effects of such an aerobic degradation process on gas–water mass transfer and dissolution of trapped gas in porous media. As a surrogate for microbial oxygen reduction, first-order oxygen demand reactions were based on the measured oxidation of alkaline pyrogallol in column experiments. This reaction allows for adjusting the rate to values close to expected biodegradation rates and detection of the reaction product. The experiments and model consistently demonstrated accelerated oxygen gas–water mass transfer with increasing oxygen demand rates associated with an influence on the partitioning of other gases. Thus, as the oxygen demand accelerates, less gas phase residues, consisting mainly of nitrogen, are observed, which is in general beneficial to the performance of field biosparging operations. Model results additionally predict how oxygen demand influences oxygen mass transfer for a range of biodegradation rates. A typical field case scenario was simulated to illustrate the observed coupling of oxygen consumption and gas bubble dissolution. The model provides a tool to improve understanding of trapped gas behavior in porous media and contributes to a model-assisted biosparging.

The present distribution of freshwater fish in the Alpine region has been strongly affected by colonization events occurring after the last glacial maximum (LGM), some 20 000 years ago. We use here a spatially explicit simulation framework to model and better understand their colonization dynamics in the Swiss Rhine basin. This approach is applied to the European bullhead (<I>Cottus gobio</I>), which is an ideal model organism to study fish past demographic processes since it has not been managed by humans. The molecular diversity of eight sampled populations is simulated and compared to observed data at six microsatellite loci under an approximate Bayesian computation framework to estimate the parameters of the colonization process. Our demographic estimates fit well with current knowledge about the biology of this species, but they suggest that the Swiss Rhine basin was colonized very recently, after the Younger Dryas some 6600 years ago. We discuss the implication of this result, as well as the strengths and limits of the spatially explicit approach coupled to the approximate Bayesian computation framework.

We examined acute (2 h exposure of 5-day-old larvae) and subchronic (exposure from fertilization up to an age of 11 days) effects of NiCl<SUB>2</SUB>·6H<SUB>2</SUB>O on embryos and larvae of zebrafish (<I>Danio rerio</I>), both alone and in combination with oxygen depletion. The following endpoints were recorded: acute exposure: locomotory activity and survival; subchronic exposure: hatching rate, deformations, locomotory activity (at 5, 8 and 11 days) and mortality. In acute exposures nickel chloride (7.5–15 mg Ni/L) caused decreasing locomotory activity. Oxygen depletion (≤2.45 ± 0.16 mg O<SUB>2</SUB>/L) also resulted in significantly reduced locomotory activity. In the subchronic test, exposure to ≥10 mg Ni/L resulted in delayed hatching at an age of 96 h, in decreased locomotory activity at an age of 5 days, and increased mortality at an age of 11 days (LC<SUB>20</SUB> = 9.5 mg Ni/L). The observed LOEC for locomotory activity (7.5 mg Ni/L) is in the range of environmentally relevant concentrations. Since locomotory activity was already affected by acute exposure, this parameter is recommended to supplement commonly recorded endpoints of toxicity.

The conjecture that the deleterious effects of mutations are amplified by stress or interaction with one another remains unsatisfactorily tested. It is now possible to reapproach this problem systematically by using genomic collections of mutants and applying stress-inducing conditions with a well-recognized impact on metabolism. We measured the maximum growth rate of single- and double-gene deletion strains of yeast in several stress-inducing treatments, including poor nutrients, elevated temperature, high salinity, and the addition of caffeine. The negative impact of deletions on the maximum growth rate was relatively smaller in stressful than in favorable conditions. In both benign and harsh environments, double-deletion strains grew on average slightly faster than expected from a multiplicative model of interaction between single growth effects, indicating positive epistasis for the rate of growth. This translates to even higher positive epistasis for fitness defined as the number of progeny. We conclude that the negative impact of metabolic disturbances, regardless of whether they are of environmental or genetic origin, is absolutely and relatively highest when growth is fastest. The effect of further damages tends to be weaker. This results in an average alleviating effect of interactions between stressful environment and gene deletions and among gene deletions.

Seismic reflection studies in the maar lake Laguna Potrok Aike (51°58′ S, 70°23′ W) revealed an erosional unconformity associated with a sub-aquatic lake-level terrace at a water depth of 30m. Radiocarbon-dated, multi-proxy sediment studies of a piston core from this location indicate that the sediment below this discontinuity has an age of 45kyr BP (Oxygen Isotope Stage 3), and was deposited during an interval of high lake level. In comparison to the Holocene section, geochemical indicators of this older part of the record either point towards a different sediment source or to a different transport mechanism for Oxygen Isotope Stage 3 sediments. Holocene sedimentation started again before 6790cal. yr BP, providing a sediment record of hydrological variability until the present. Geochemical and isotopic data indicate a fluctuating lake level until 5310cal. yr BP. During the late Holocene the lake level shows a receding tendency. Nevertheless, the lake level did not drop below the 30m terrace to create another unconformity. The geochemical characterization of volcanic ashes reveals evidence for previously unknown explosive activity of the Reclús and Mt. Burney volcanoes during Oxygen Isotope Stage 3.

Scientists working closely on issues of water reuse are far from having solved all concerns related to the practice. From the very beginning of a water reuse project, scenarios must be prepared from the 'zero scenario' (no reuse) through to more complex and expensive ones (e.g. reverse osmosis for potable water treatment) to help stakeholders to select the best option for increasing available water resources, the ultimate purpose of reuse. In any case, the use of adequate tools to build scenarios is paramount. From Decision Support Systems to the simplest analytical tools, all knowledge is valuable. Detailed studies must be undertaken to identify necessary technologies, schemes and control tools. As public health concerns are normally among the main constraints for reuse any scenario will need to include detailed risk assessments. To achieve an adequate risk assessment, data pertaining to microbiological, chemical and biological factors is necessary. Unfortunately, suitable techniques and criteria are not always established by rules and regulations. However, several strong attempts have been made in some countries. Once the basic calculations were performed, a final decision whether the scheme can be implemented should be based on three phases of risk assessment; analysis, calculation and communication. This will allow fulfilling the key objectives of reuse: increasing the amount of water resources available, under an acceptable risk with a public full knowledge.

We examined vertical changes in microbial lipid composition and functional genes in the 4.5 m deep water column of a highly contaminated, meromictic lake in eastern Massachusetts. Lipid based techniques and compound specific isotopic analysis indicate marked differences in community structure between the sulfate and methane laden hypolimnion and the aerated epiliminon. The major intact polar lipids (IPLs) detected throughout the water column include diacyl phosphatidylethanolamine, its methylated derivatives phosphatidylmethylethanolamine and phosphatidyldimethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, and the glycolipids monoglycosyldiacylglycerol and glycuronic acid dialkylglycerol. These compounds are attributed mainly to bacteria. The predominance of betaine lipids in the epilimnion is consistent with the dominant role of eukaryotic photoautotrophs in the oxic surface. Bacteriohopanepolyols and slight negative inflections of δ<SUP>13</SUP>C values of bacterial phospholipid-bound fatty acids (PLFAs) at the metalimnion indicate a low contribution of methanotrophic bacteria to the pool of metalimnic bacteria. In the hypolimnion, dialkylglycerol-phosphatidylethanolamine, C<SUB>17</SUB>-PLFAs and dsrAB gene sequence data suggest the presence of sulfate reducing bacteria (SRB). Five distinct groups of sulfate reducers and methanogens were detected in the hypolimnion. While SRB appear to inhabit the hypolimnion, the methanogens most likely entered the lake through the inflow of methane laden groundwater. We did not detect either of the methyl-coenzyme M reductase genes or characteristic lipids related to known anaerobic methane oxidizing Archaea although the hypolimnion exhibited conditions conducive to anaerobic methanotrophy. The large amount of dissolved organic carbon appears to be the major pool of carbon for the lake's microbial biomass.

A multichannel, high-resolution seismic reflection survey was conducted with an airgun source in the closed lake system of Lago Cardiel, Argentina (49°S). As part of an ongoing study of interhemispheric correlations in climate change, it was intended to determine the maximum age and depth of the lake sediments and better understand the origin and evolution of the lake basin. In agreement with previous single-channel, 3.5-kHz surveys, six major seismic sequences throughout the lake's subsurface were mapped. The stronger seismic source of this study allows the deepest sequence (Sequence VI) to be interpreted as folded Cretaceous marls with a highly eroded surface. Further examination of this sequence reveals various stratigraphic signatures and mechanisms of the generally east-west orientation of tectonic compression. The nature and continuity of Sequence VI do not indicate a volcanic or impact-related origin of the lake. The original basin has a maximal depression of 154 ms (∼114 m) deep beneath the modern lake surface and is overlain by an alluvial fan (Sequence V) of likely Pleistocene age in the western portion and late Quaternary lacustrine sediments (Sequences I-IV) everywhere else. The data confirm that southern Patagonia was dominated by extremely contrasting climatic conditions during the Quaternary.

Information exchange in policy networks is usually attributed to preference similarity, influence reputation, social trust, and institutional actor roles. We suggest that political opportunity structures and transaction costs play another crucial role and estimate a rich statistical network model on tie formation in the German toxic chemicals policy domain. The results indicate that the effect of preference similarity is absorbed by institutional, relational, and social opportunity structures. Political actors choose contacts who minimize transaction costs while maximizing outreach and information. We also find that different types of information exchange operate in complementary, but not necessarily congruent, ways.

In 2005, the European Parliament rejected the directive ‘on the patentability of computer-implemented inventions’, which had been drafted and supported by the European Commission, the Council and well-organised industrial interests, with an overwhelming majority. In this unusual case, a coalition of opponents of software patents prevailed over a strong industry-led coalition. In this article, an explanation is developed based on political discourse showing that two stable and distinct discourse coalitions can be identified and measured over time. The apparently weak coalition of software patent opponents shows typical properties of a hegemonic discourse coalition. It presents itself as being more coherent, employs a better-integrated set of frames and dominates key economic arguments, while the proponents of software patents are not as well-organised. This configuration of the discourse gave leeway for an alternative course of political action by the European Parliament. The notion of discourse coalitions and related structural features of the discourse are operationalised by drawing on social network analysis. More specifically, discourse network analysis is introduced as a new methodology for the study of policy debates. The approach is capable of measuring empirical discourses both statically and in a longitudinal way, and is compatible with the policy network approach.