The Intergovernmental Panel on Climate Change (IPCC) Technical Paper Climate Change and Water draws together and evaluates the information in IPCC Assessment and Special Reports concerning the impacts of climate change on hydrological processes and regimes, and on freshwater resources – their availability, quality, use and management. It takes into account current and projected regional key vulnerabilities, prospects for adaptation, and the relationships between climate change mitigation and water. Its objectives are:

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Climate change and water.

1 Plant ecology at high elevations.- The concept of limitation.- A regional and historical account.- The challenge of alpine plant research.- 2 The alpine life zone.- Altitudinal boundaries.- Global alpine land area.- Alpine plant diversity.- Origin of alpine floras.- Alpine growth forms.- 3 Alpine climate.- Which alpine climate.- Common features of alpine climates.- Regional features of alpine climates.- 4 The climate plants experience.- Interactions of relief, wind and sun.- How alpine plants influence their climate.- The geographic variation of alpine climate.- 5 Life under snow: protection and limitation.- Temperatures under snow.- Solar radiation under snow.- Gas concentrations under snow.- Plant responses to snowpack.- 6 Alpine soils.- Physics of alpine soil formation.- The organic compound.- The interaction of organic and inorganic compounds.- 7 Alpine treelines.- About trees and lines.- Current altitudinal positions of climatic treelines.- Treeline-climate relationships.- Intrazonal variations and pantropical plateauing of alpine treelines.- Treelines in the past.- Attempts at a functional explanation of treelines.- A hypothesis for treeline formation.- Growth trends near treelines.- Evidence for sink limitation.- 8 Climatic stress.- Survival of low temperature extremes.- Avoidance and tolerance of low temperature extremes.- Heat stress in alpine plants.- Ultraviolet radiation - a stress factor.- 9 Water relations.- Ecosystem water balance.- Soil moisture at high altitudes.- Plant water relations - a brief review of principles.- Water relations of alpine plants.- Desiccation stress.- Water relations of special plant types.- 10 Mineral nutrition.- Soil nutrients.- The nutrient status of alpine plants.- Nutrient cycling and nutrient budgets.- Nitrogen fixation.- Mycorrhiza.- Responses of vegetation to variable nutrient supply.- 11 Uptake and loss of carbon.- Photosynthetic capacity of alpine plants.- Photosynthetic responses to the environment.- Daily carbon gain of leaves.- The seasonal carbon gain of leaves.- C4 and CAM photosynthesis at high altitudes.- Tissue respiration of alpine plants.- Ecosystem carbon balance.- 12 Carbon investments.- Non-structural carbohydrates.- Lipids and energy content.- Carbon costs of leaves and roots.- Whole plant carbon allocation.- 13 Growth dynamics and phenology.- Seasonal growth.- Diurnal leaf extension.- Rates of plant dry matter accumulation.- Functional duration of leaves and roots.- 14 Cell division and tissue formation.- Cell size and plant size.- Mitosis and the cell cycle.- From meristem activity to growth control.- 15 Plant biomass production.- The structure of alpine plant canopies.- Primary productivity of alpine vegetation.- Plant dry matter pools.- Biomass losses through herbivores.- 16 Plant reproduction.- Flowering and pollination.- Seed development and seed size.- Germination.- Alpine seed banks and natural recruitment.- Clonal propagation.- Alpine plant age.- Community processes.- 17 Global change at high elevation.- Alpine land use.- The impact of altered atmospheric chemistry.- Climatic change and alpine ecosystems.- References (with chapter annotation).- Taxonomic index (genera).- Geographical index.- Color plates.- Plant life forms.- The alpine life zone.- Environmental stress.- The human dimension.

Alpine plant life

The Domain-specific Probe EUB338 is Insufficient for the Detection of all Bacteria: Development and Evaluation of a more Comprehensive Probe Set

The discovery that viruses may be the most abundant organisms in natural waters, surpassing the number of bacteria by an order of magnitude, has inspired a resurgence of interest in viruses in the aquatic environment. Surprisingly little was known of the interaction of viruses and their hosts in nature. In the decade since the reports of extraordinarily large virus populations were published, enumeration of viruses in aquatic environments has demonstrated that the virioplankton are dynamic components of the plankton, changing dramatically in number with geographical location and season. The evidence to date suggests that virioplankton communities are composed principally of bacteriophages and, to a lesser extent, eukaryotic algal viruses. The influence of viral infection and lysis on bacterial and phytoplankton host communities was measurable after new methods were developed and prior knowledge of bacteriophage biology was incorporated into concepts of parasite and host community interactions. The new methods have yielded data showing that viral infection can have a significant impact on bacteria and unicellular algae populations and supporting the hypothesis that viruses play a significant role in microbial food webs. Besides predation limiting bacteria and phytoplankton populations, the specific nature of virus-host interaction raises the intriguing possibility that viral infection influences the structure and diversity of aquatic microbial communities. Novel applications of molecular genetic techniques have provided good evidence that viral infection can significantly influence the composition and diversity of aquatic microbial communities.

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Virioplankton: viruses in aquatic ecosystems

The finding that total viral abundance is higher than total prokaryotic abundance and that a significant fraction of the prokaryotic community is infected with phages in aquatic systems has stimulated research on the ecology of prokaryotic viruses and their role in ecosystems. This review treats the ecology of prokaryotic viruses ('phages') in marine, freshwater and soil systems from a 'virus point of view'. The abundance of viruses varies strongly in different environments and is related to bacterial abundance or activity suggesting that the majority of the viruses found in the environment are typically phages. Data on phage diversity are sparse but indicate that phages are extremely diverse in natural systems. Lytic phages are predators of prokaryotes, whereas lysogenic and chronic infections represent a parasitic interaction. Some forms of lysogeny might be described best as mutualism. The little existing ecological data on phage populations indicate a large variety of environmental niches and survival strategies. The host cell is the main resource for phages and the resource quality, i.e., the metabolic state of the host cell, is a critical factor in all steps of the phage life cycle. Virus-induced mortality of prokaryotes varies strongly on a temporal and spatial scale and shows that phages can be important predators of bacterioplankton. This mortality and the release of cell lysis products into the environment can strongly influence microbial food web processes and biogeochemical cycles. Phages can also affect host diversity, e.g., by 'killing the winner' and keeping in check competitively dominant species or populations. Moreover, they mediate gene transfer between prokaryotes, but this remains largely unknown in the environment. Genomics or proteomics are providing us now with powerful tools in phage ecology, but final testing will have to be performed in the environment.

Ecology of prokaryotic viruses

Transformation of organic and inorganic material in the atmosphere has been presumed to be caused by physical and chemical processes in the gas phase and in aerosol particles. Here we show that bacterial metabolism can play a measurable role in the production and transformation of organic carbon in cloud droplets collected at high altitudes, even at temperatures at or well below 0 degree(s)C. Although bacterial abundance and biomass in cloud water is low, compared to other oligotrophic aquatic environments, growth and carbon production rates per cell are approximately as high as in aquatic ecosystems. We hypothesize that microorganisms could play a crucial role in the transformation of airborne organic matter and the chemical composition of snow and rain. It has been recognized, the microbes can act as cloud condensation nuclei but we consider the impact on the global climate as low. With an increasing trend in cloudiness cloud systems can be seen as an ecosystem for active microbes with a seeding effort both for aquatic and terrestrial realms. Furthermore, air currents can distribute microbes over long distances to remote areas e.g. like ice caps and snow fields.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Clouds as habitat and seeders of active bacteria

Lakes of Europe show a great variability in their characteristics, with boreal lakes at northern latitudes as the most abundant lake type. The variability is a result of large gradients in climate, geological history, land use, and atmospheric deposition, mainly along a north–south axis. Worldwide, the best known lakes are probably Europe's lakes in the Alp region, most likely due to their spectacular surroundings and their long tradition of providing good research facilities with all necessary infrastructure. Lakes of Europe, including very remote lakes, are subjected to multiple stressors, climate change and atmospheric deposition being examples. These stressors can cause water quality problems. One of the most common water quality problems occurring in all European countries have been and still are harmful algal blooms.

Lakes of Europe

Despite their remoteness, mountain lake ecosystems throughout the arctic and alpine regions of the world are under pressure from a range of environmental threats acting singly or in combination. These include acid deposition, toxic meta! and toxic organic compounds, uv-b radiation, and greenhouse gas-forced climatic warming. The importance of studying how lakes respond to these pressures is apparent, and such studies have added significance as the lakes, together with their unique sediment records, act as environmental sensors of change for the wider arctic and alpine environment. This paper provides a summary of a major collaborative project (Table l) on remote mountain lakes sponsored by the European Commission. The project began in 1991 as tbe AL:PE Project (WATHNE et al. 1995). In the early phase of AL:PE much of the work carried out was exploratory, aimed at characterising the chemistry and biology of the sites and assessing their pollurion status from lake sediment records. In the current MOLAR project the focus is on detailed studies of a smaller number of key sites to provide high resolution spatial and temporal data that can be used in the development and calibration of predictive models.

Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change (the MOLAR project)

For more than half a year, the ice-cover of high altitude lakes builds a bridge between adjacent ecosystems the lake, its catchment and the atmosphere. Microorganisms of pelagic, benthic and airborne origin inhabit the different snow-slush layers of the winter cover oflakes in high alpine regions with relatively high precipitation. The autotrophic and heterotrophic assemblages differ significantly between lake water and ice-cover (FELIP et al. 1995, 1999, ALFREIDER et al. 1996, PSENNER et al. 1999). Therefore, this habitat can be considered as an ecotone which is newly formed each year. We observed the evolution of the ice-cover of the shallow high-mountain lake Gossenkiillesee, situated in the Central Austrian Alps. We measured the rates of algal primary production and bacterial secondary production simultaneously in situ in the winter cover and in the water column over one winter and one summer period. At the time of maximum ice thickness, the winter cover represented about 38% of the whole lake volume and inhibited light transmission up to 99.9%, while in the uppermost slush layer 16% of the incoming light was still available. In early winter when the ice-cover was growing, pelagic algae and bacteria were infiltrated from the lake water in to the establishing slush layers of the winter cover. Phytoplankton in the water column declined (7.53-0.31 flg Chl a V) until ice break at the end of June. The decrease of these pelagic algae resulted in enhanced bacterial production in both the pelagic zone and the winter cover (up to 0.22 pg C V h-'). On top of the ice-cover, a new algal assemblage developed, dominated by Chlamydomonas sp., but also high densities of benthic diatoms, e.g. Cyclotella gordonensis and Achnanthes sp. (KOINIG et al. 2000), were observed. Preliminary results show a maximum photosynthetic rate (P mJ at a light intensity of 340-360 fJmol m·' ç', and the primary production rate increased from 0.003 up to 3.5 flg C L-' h-'. Algae from the deeper slush layers and from the water-column showed a P ma between 40 and 100 flmol m·' ç' suggesting low light adaptation. Except for the time of maximum ice thickness, the lake was found to be an autotrophic system whereas the winter cover itself seemed to be mainly heterotrophic. Finally, with the establishment of a new algal assemblage, autotrophic production of the winter cover exceeded heterotrophic production 570fold.

Lake ice microbial communities (LIMCO) — biology of a periodic ecotone

In spring 2004, a massive infestation of the whitefish population in the Austrian Lake Achensee with Triaenophorus crassus was observed. Procercoids, the larval stage of parasitic cestodes, infest copepods as their first intermediate host. Therefore, in spring 2011, zooplankton samples were taken weekly at two sampling sites and depth ranges to determine the abundances of crustaceans as well as percentages of infected copepods and temporal occurrence of parasites. In addition, whitefish ( Coregonus lavaretus ) stomach contents were analysed for food spectrum and parasite infestation. From the end of June to mid-August, procercoids of Triaenophorus spp. were detected in Cyclops abyssorum , the only first intermediate host for this parasite in Lake Achensee. Highest percentages of infected copepods were reached in mid-July (prevalence: 0.38%). Furthermore, an infestation of Proteocephalus sp. was observed in this copepod species, which occurred earlier until the end of the sampling period (prevalence: 1.34%). Besides C. abyssorum , also Eudiaptomus gracilis was occasionally infected with Proteocephalus (prevalence: 0.05%). The procercoids were found in both depth ranges, with no clear vertical infestation preference. More female C. abyssorum were Triaenophorus -infected than males, while the opposite was observed for Proteocephalus infection. The whitefish stomachs contained large numbers of Proteocephalus and Triaenophorus procercoids, coinciding with the occurrence of these parasites in the copepods.

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Roland Psenner

Papers

Clouds as habitat and seeders of active bacteria

Lakes of Europe

Measuring and modelling the dynamic response of remote mountain lake ecosystems to environmental change (the MOLAR project)

Lake ice microbial communities (LIMCO) — biology of a periodic ecotone

Infestation of zooplankton with Triaenophorus and Proteocephalus procercoids (Cestoda) in a deep oligotrophic lake