Ecology of<Emphasis Type="Italic"> Leptothorax</Emphasis> ants: impact of food,nest sites,and social parasites

In a long-term field manipulation, we demonstrate strong reactions of Leptothorax longispinosus ant colonies to food- and nest-site supplementation. Demographic and genetic responses varied over small geographic scales, and the two ecological factors interacted with the presence of the social parasite Protomognathus americanus. We conducted a 2×2 experiment in three blocks and found that the blocks, which were less than 100 m apart, reacted very differently to the treatments. Blocks differed in degree of polygyny, intranest relatedness, colony size, productivity, and sexual investment. Furthermore, these differences were associated with the presence of slave-making ants and the local availability of nest sites. Nest-site supplementation had a strong effect only in the site with the highest prevalence of social parasites, influencing there the density and investment patterns of colonies. L. longispinosus ants in the least parasitized area were strongly affected by both food- and nest-site supplementation. There, food supplementation led to a decrease in the number of queens per colony and consequently to an increase in intranest relatedness, while colonies in nest-site-supplemented areas invested fewer resources in males and produced a female-biased allocation ratio. By contrast, in a third block with a very low intracolonial relatedness, food supplementation induced an absolute and relative higher investment in males. We conclude that ecological factors influencing social organization in insect societies cannot be studied in isolation, because the interactions among factors produce far richer responses than any one variable.Communicated by L. Sundström     

Hochwasser 2002

In August 2002, highly contaminated areas in the region of Bitterfeld, e.g. the floodplain of the creek Spittelwasser, as well as the adjacent regions of Jeßnitz and Raguhn, were submerged by the river Mulde. An input of mobilized contaminated sediments in residential areas was the matter of concern. The objective of the present study was to estimate the pollutants load on the basis of chemical and biological data and identify the sources of pollutants. Deposited sludge and flood water samples were assessed on the basis of biological and chemical analyses and in comparison with administrative reference values. The pollution of the investigated sites was rather heterogeneous. At several sites, tolerance limits of the German Klärschlammverordnung or the Bundesbodenschutzverordnung were clearly exceeded, e.g. for Pb, As and HCH. Organic extracts exhibited significant effects in several biotests. This may be relevant with respect to direct particle uptake via ingestion or respiration. Pollution patterns for heavy metals as well as for organic pollutants differed significantly from the pattern found in the Spittelwasser flood plain before the inundation, which is in contrast to the initial hypothesis of a possible transport of contaminated Spittelwasser sediments into residential areas. Interestingly, a correlation of chemical load and the overall biological effect could be shown. From the viewpoint of the precautionary principle, the identification of the compounds exerting toxic effects and of the respective pollutant sources would be desirable.     

Improving marine water quality by mussel farming: a profitable solution for Swedish society

Eutrophication of coastal waters is a serious environmental problem with high costs for society globally. In eastern Skagerrak, reductions in eutrophication are planned through reduction of nitrogen inputs, but it is unclear how this can be achieved. One possible method is the cultivation of filter-feeding organisms, such as blue mussels, which remove nitrogen while generating seafood, fodder and agricultural fertilizer, thus recycling nutrients from sea to land. The expected effect of mussel farming on nitrogen cycling was modeled for the Gullmar Fjord on the Swedish west coast and it is shown that the net transport of nitrogen (sum of dissolved and particulate) at the fjord mouth was reduced by 20%. Existing commercial mussel farms already perform this service for free, but the benefits to society could be far greater. We suggest that rather than paying mussel farmers for their work that nutrient trading systems are introduced to improve coastal waters. In this context an alternative to nitrogen reduction in the sewage treatment plant in Lysekil community through mussel farming is presented. Accumulation of bio-toxins has been identified as the largest impediment to further expansion of commercial mussel farming in Sweden, but the problem seems to be manageable through new techniques and management strategies. On the basis of existing and potential regulations and payments, possible win-win solutions are suggested.     

Hypoxia-induced structural changes in the diet of bottom-feeding fish and Crustacea

Interactive effects of three alternating normoxia-hypoxia cycles on benthic prey exploitation by mobile fish (spot, Leiostomus xanthurus; and hogchoker, Trinectes maculatus) and a burrowing crustacean (Squilla empusa) were investigated in the York River, Chesapeake Bay, Virginia, USA, in 1989. Predators collected in four depth strata (A: 5 to 10 m; B: 10 to 14 m; C: 14 to 20 m; D:>20 m) variously affected by hypoxia were separated into size classes (three for spot and two each for hogchoker and mantis shrimp) to examine potential ontogenetic influences in prey selection. The most severe effects of hypoxia on the benthos occurred in the two deepest strata (C and D) and decreased in shallower strata (B>A), with Stratum A never affected by low oxygen. Predators investigated exhibited dietary evidence of optimal prey exploitation during or immediately after hypoxic events. In most instances gut contents contained significantly larger, deeper-burrowing prey during periods of low oxygen than during alternating peroids of normal oxygen levels. Spot consumed a greater biomass (45 to 73%) of polychaetes than other prey, with crustaceans initially also constituting a main dietary component but decreasing in importance later in the study period. The deep-burrowing anemone, Edwardsia elegans, was an important prey species for spot, particularly in the lower depth strata affected by hypoxia. Prey consumed by 10-to 15-cm-long spot increased significantly in size during some hypoxic events, suggesting a sublethal effect of hypoxia on large benthic species. Polychaetes (primarily Glycera americana, Notomastis latericeus and Loimia medusa) were dominant dietary components in hogchoker, making up between 85 and 98% of the diet. Bivalve siphons became important prey for hogchoker in the three deepest strata and were only consumed after the August hypoxia. Stomach contents of mantis shrimp were difficult to identify in most instances due to the near complete mastication of consumed prey. Crustaceans were important prey initially but became less conspicuous in the diet subsequent to the July hypoxia event, when hydroids became more dominant. Overall, predator species exhibited optimal exploitation of moribund or slowly recovering benthos affected by hypoxia. The sublethal effects of hypoxia through increased availability of benthos to resident predators can have important consequences for energy flow in areas such as the York River which experience periodic low-oxygen cycles.     

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter

In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60 days using a real farmer''s pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability.     

The Swedish joint action method against drink driving—a study of suspected drink drivers' own experiences

Objective: In Sweden, a joint action method called SMADIT is in use, where the police quickly offer help from the social services or the dependency care and treatment service to suspected drink drivers. The objective of this article is to analyze the experiences of suspected drink drivers who accepted the offer of help and what it meant for them. The knowledge can be used to improve procedures and consultations. Furthermore, it can allow the basic premises of the method to be examined; for example, the importance of offering help quickly.

Methods: To enable comparisons over time, in-depth interviews were conducted with 12 suspected drink drivers on 2 occasions with 1 year between.

Results: To varying degrees the informants knew about their alcohol problems but were unsure whether they would have sought help by themselves. Therefore, the original ideas of the method with an initial contact with the social services or the dependency care and treatment service within 24 h was found to be important. However, the results also showed that some of the informants needed some time before the first meeting because they were in shock from the drink driving incident or in need of sleep. Therefore, the drink driver's situation and individual wishes always have to be considered. The article also shows that an encouraging attitude among the police, the social services, and the dependency care and treatment service is important for the success of the SMADIT method.

The informants are satisfied with the method and in retrospect the incident and the SMADIT offer of help are described as a turning point in their lives. One year after being offered help the informants were no longer focused solely on the personal consequences of drink driving, as they were shortly after the incident. Instead, they had gained insights into the harm they could have done to other road users when they drove while drunk.

Conclusions: One conclusion from this article is that SMADIT, as an innovative method that can be deployed more rapidly than other alcohol-impaired driving countermeasures, should be considered as a good complement to conventional methods to deal with drink driving. Based on the results, we recommend a trial of the joint action method against drink driving in other jurisdictions.     

Leaching of benzimidazole antiparasitics in soil columns and in soil columns amended with sheep excreta

Environmental Science and Pollution Research - Benzimidazoles are anthelmintics frequently used in sheep farming due to the high susceptibility of these animals to parasitic diseases. Sheep excreta...     

Climate change in a regional context: relative vulnerability in the Australasian skier market

The concept of relative vulnerability allows for comparisons between analogous units in a regional context. It is utilised within tourism studies to consider how climate change might affect demand and perceived attractiveness of destinations relative to their competitors. This paper examines Australian tourists travelling to New Zealand’s ski fields, responding to the intergovernmental panel on climate change (IPCC) assertion that, “tourist flows from Australia to New Zealand might grow as a result of the relatively poorer snow conditions in Australia” (Hennessy et al. 2007: p 523). This travel flow is not a new phenomenon; however, it is forecast to increase as climate change impacts upon Australia’s natural and man-made snowmaking capacity with implications for the viability of the ski industries in both Australia and New Zealand. The Queenstown Lakes Region (South Island, New Zealand) serves as the field area for this study. The empirical research utilises a qualitative methodology for which in-depth, semi-structured interviews were conducted with New Zealand ski industry representatives and Australian tourists during the southern hemisphere winter season of 2011. Findings suggest that the social context of vulnerability creates difficulty in forecasting the outcomes and behaviours associated with relative vulnerability. While tourism representatives’ focus on snow reliability and availability to conceptualise relative vulnerability, Australian tourists are influenced by a broader range of factors including their own travel experience. This paper demonstrates a clear need to move beyond a focus on snow reliability to consider the broad range of factors that contribute to regional variations in vulnerability. In doing so, it confirms the critical importance of situating relative vulnerability within a social context.     

Comparison of microbial pyrene and benzo[a]pyrene mineralization in liquid medium, soil slurry, and soil

The microbial degradation of 14C-pyrene and 14C-benzo[a]pyrene by a bacterial mixed culture was studied within a mixture of the PAHs phenanthrene, anthracene, pyrene, fluoranthene, and benzo[a]pyrene as sole carbon source in the different culture systems: (i) liquid medium, (ii) soil slurry (surface and grinding influence), and (iii) soil. The fate of these two labeled compounds was followed in these systems with an emphasis on mineralization to carbon dioxide, extractability, and adsorption to humic materials and formation of unextractable residual. Mineralization showed the most obvious differences: soil slurries achieved the best results both concerning the extent of mineralization and the time required. The highest extent of pyrene mineralization (54% within 21 days) was observed in soil slurries; in liquid media, pyrene mineralization was slower, but reached approximately the same extent (54% in 150 days); in soils, mineralization reached only 36% of added pyrene after 160 days. Benzo[a]pyrene was mineralized in a mixture of PAHs in soil slurries to an extent of 34% within 70 days, whereas mineralization in liquid medium and soil occurred in the range of 5% (70 days). Mineralization of benzo[a]pyrene in sand slurries was lower compared to soil slurries (19% in sand slurries vs. 32% in soil slurries within 50 days).