Environmental issues in lakes and ponds: current state and perspectives

Lakes and ponds are habitats of great human importance as they provide water for domestic, industrial and agricultural use as well as providing food. In spite of their fundamental importance to humans, freshwater systems have been severely affected by a multitude of anthropogenic disturbances, which have led to serious negative effects on the structure and function of these ecosystems. The aim of the present study is to review the current state of lake and pond ecosystems and to present a likely scenario for threats against these ecosystems for the time horizon of the year 2025. Predictions are based on a review of the current state, projections of long-term trends, for example in population and global climate, and an analysis of the trends in publications in the scientific literature during the past 25 years (1975-2000). The biodiversity of lake and pond ecosystems is currently threatened by a number of human disturbances, of which the most important include increased nutrient load, contamination, acid rain and invasion of exotic species. Analysis of trends suggests that older, well known threats to biodiversity such as eutrophication, acidification and contamination by heavy metals and organochlorines may become less of a problem in developed countries in the future. New threats such as global warming, ultraviolet radiation, endocrine disruptors and, especially, invasion by exotic species including transgenic organisms will most likely increase in importance. However, in developing countries where priorities other than environmental conservation exist, the threat of eutrophication, acidification and contamination by toxic substances is predicted to continue to increase. Although the future of biodiversity in lakes and ponds is seriously threatened, growing concern for environmental problems, implementation of new environmental strategies and administrations, and international agreements, are positive signs of changes that should improve the ability to manage old as well as new, yet undiscovered, threats

UVB-induced inflammation gives increased d-dopachrome tautomerase activity in blister fluid which correlates with macrophage migration inhibitory factor.

UVB light was used to induce an experimental inflammation in normal human skin in order to investigate its correlation with the activity of the newly described enzyme d-dopachrome tautomerase (DDT) in the fluid of experimental blisters. Macrophage migration inhibitory factor (MIF) activity was determined as a closely related marker of inflammation. DDT and MIF activities were demonstrated in blister fluids in all 10 healthy subjects. All but one of these subjects showed increased activity of DDT and MIF after three minimal erythemal doses (MED) of UVB. The mean activity of DDT increased approximately twofold and the mean activity of MIF also increased twofold after UVB in our experimental model. We found a strong correlation between DDT and MIF activities. The presence of DDT in epidermis and its increase at UV irradiation was confirmed by immunohistochemical studies. In this study, DDT is for the first time demonstrated in the skin. It is also the first time DDT can be related to inflammation, and its covariation with MIF strengthens this observation

Invading herbivory: The golden apple snail alters ecosystem functioning in Asian wetlands

We investigated the effects of an exotic snail, the golden apple snail (Pomacea canaliculata) on biodiversity and ecosystem functioning in tropical wetland ecosystems. This large snail (up to 80-mm shell height) has invaded large parts of Southeast Asia during recent decades. A survey of natural wetlands in Thailand showed that high densities of the snail were associated with almost complete absence of aquatic plants, high nutrient concentrations, and high phytoplankton biomass, that is, a complete shift in both ecosystem state and function. A field experiment demonstrated that grazing by the snail can cause the loss of aquatic plants, a change toward dominance of planktonic algae, and thereby a shift toward turbid water. Estimates of biologically fixed nutrients released through snails grazing on aquatic plants revealed that phosphorus releases were sufficient to explain the recorded increase in phytoplankton biomass. Hence, our study demonstrates how an herbivore may trigger a shift from clear water and macrophyte dominance to a turbid state dominated by planktonic algae. This shift and the continuing aggressive invasion of this exotic species are detrimental to the integrity and functioning of wetland ecosystems, and to the services these provide in Southeast Asia

Metastable Markov chains: from the convergence of the trace to the convergence of the finite-dimensional distributions

We consider continuous-time Markov chains which display a family of wells at the same depth. We provide sufficient conditions which entail the convergence of the finite-dimensional distributions of the order parameter to the ones of a finite state Markov chain. We also show that the state of the process can be represented as a time-dependent convex combination of metastable states, each of which is supported on one well

Mesopolobus incultus auct. (Hymenoptera: Pteromalidae) contains two distinct species: Mesopolobus incultus (Walker, 1834) and Mesopolobus amyntor (Walker, 1845)

Mesopolobus incultus auct. is hypothesized to consist of twodifferent species, M. amyntor (Walker) and M. incultus (Walker). This hypothesis is supported bymolecular(cytochromec oxidase subunit I, i.e. COI), morphological and biologicaldata.Mesopolobus amyntor is a primary parasitoid of Mecinus pascuorum (Gyllenhal) and M. labilis (Herbst) (Coleoptera: Curculionidae) on Plantago lanceolata. Mesopolobus incultus is a primary parasitoid of Protapion fulvipes (Geoffroy) (Coleoptera: Apionidae) on Trifolium repens and T. pratense, and hasalso been inferred to act as a secondary parasitoid (hyperparasitoid) of Spintherus dubius (Nees) (Hymenoptera: Pteromalidae) or Bruchophagus gibbus (Boheman) (Hymenoptera: Eurytomidae). The results of this study lead to following nomenclatural changes: M. amyntor is removed from synonymy under M. incultus, and Pteromalus urgo, P. belesis and P. berecynthos, all described by Walker, are synonymized under M. amyntor. The species are diagnosed with characters illustrated

Störningar inom kontrollzon

This paper is partially a literature study of human error and interruptions and partially an investigation of pilots and Air Traffic Control. The aim of the investigation was to find out where interruptions occur and how to reduce or eliminate them. The objective of this paper was to investigate what type of interruptions pilots and ATC deals with and during which phases they occur. The paper has revealed that private pilots causes more interruptions for ATC personnel than commercial pilots. The cause for this is probably the less experienced private pilot and the fact that Swedish is used before English by private pilots in communication with ATC. Further on the paper has revealed that communication with ATC causes most interruptions for commercial pilots and that interruptions caused by flight attendants have decreased. The latter is probably caused by the Crew Resource Managment courses. It is when using approach checklist most interruptions occur and there are three different techniques for memorizing the item on the checklist: "Thumb in track", callout "Hold at item..." or simply just memorize present item. The latter technique is not to be recommended due to the limited resources of the human working memory

Seasonal Migration Determined by a Trade-Off between Predator Avoidance and Growth

Migration is a common phenomenon in many organisms, terrestrial as well as aquatic, and considerable effort has been spent to understand the evolution of migratory behaviour and its consequences for population and community dynamics. In aquatic systems, studies on migration have mainly been focused on commercially important fish species, such as salmon and trout. However, seasonal mass-migrations may occur also among other freshwater fish, e.g. in cyprinids that leave lakes and migrate into streams and wetlands in the fall and return back to the lake in spring. In a conceptual model, we hypothesized that this is an adaptive behaviour in response to seasonal changes in predation (P) and growth (G) and that migrating fish change habitat so as to minimise the ratio between predation mortality and growth rate (P/G). Estimates from bioenergetic modelling showed that seasonal changes in the ratio between predator consumption rate and prey growth rate followed the predictions from the conceptual model and also gave more precise predictions for the timing of the habitat change. By quantifying the migration of more than 1800 individually marked fish, we showed that actual migration patterns followed predictions with a remarkable accuracy, suggesting that migration patterns have evolved in response to seasonally fluctuating trade-offs between predator avoidance and foraging gains. Thus, the conceptual model provides a mechanistic understanding to mass–migration in prey fish. Further, we also show that the dominant prey fish is actually absent from the lake during a major part of the year, which should have strong implications for the dynamics of the lake ecosystem through direct and indirect food-web interactions

Putative ligand binding sites of two functionally characterized bark beetle odorant receptors

Background: Bark beetles are major pests of conifer forests, and their behavior is primarily mediated via olfaction. Targeting the odorant receptors (ORs) may thus provide avenues towards improved pest control. Such an approach requires information on the function of ORs and their interactions with ligands, which is also essential for understanding the functional evolution of these receptors. Hence, we aimed to identify a high-quality complement of ORs from the destructive spruce bark beetle Ips typographus (Coleoptera, Curculionidae, Scolytinae) and analyze their antennal expression and phylogenetic relationships with ORs from other beetles. Using 68 biologically relevant test compounds, we next aimed to functionally characterize ecologically important ORs, using two systems for heterologous expression. Our final aim was to gain insight into the ligand-OR interaction of the functionally characterized ORs, using a combination of computational and experimental methods. Results: We annotated 73 ORs from an antennal transcriptome of I. typographus and report the functional characterization of two ORs (ItypOR46 and ItypOR49), which are responsive to single enantiomers of the common bark beetle pheromone compounds ipsenol and ipsdienol, respectively. Their responses and antennal expression correlate with the specificities, localizations, and/or abundances of olfactory sensory neurons detecting these enantiomers. We use homology modeling and molecular docking to predict their binding sites. Our models reveal a likely binding cleft lined with residues that previously have been shown to affect the responses of insect ORs. Within this cleft, the active ligands are predicted to specifically interact with residues Tyr84 and Thr205 in ItypOR46. The suggested importance of these residues in the activation by ipsenol is experimentally supported through site-directed mutagenesis and functional testing, and hydrogen bonding appears key in pheromone binding. Conclusions: The emerging insight into ligand binding in the two characterized ItypORs has a general importance for our understanding of the molecular and functional evolution of the insect OR gene family. Due to the ecological importance of the characterized receptors and widespread use of ipsenol and ipsdienol in bark beetle chemical communication, these ORs should be evaluated for their potential use in pest control and biosensors to detect bark beetle infestations