Does the Danube exist? Versions of reality given by various regional climate models and climatological datasets

We present an intercomparison and verification analysis of several regional climate models (RCMs) nested into the same run of the same Atmospheric Global Circulation Model (AGCM) regarding their representation of the statistical properties of the hydrological balance of the Danube river basin for 1961-1990. We also consider the datasets produced by the driving AGCM, from the ECMWF and NCEP-NCAR reanalyses. The hydrological balance is computed by integrating the precipitation and evaporation fields over the area of interest. Large discrepancies exist among RCMs for the monthly climatology as well as for the mean and variability of the annual balances, and only few datasets are consistent with the observed discharge values of the Danube at its Delta, even if the driving AGCM provides itself an excellent estimate. Since the considered approach relies on the mass conservation principle and bypasses the details of the air-land interface modeling, we propose that the atmospheric components of RCMs still face difficulties in representing the water balance even on a relatively large scale. Their reliability on smaller river basins may be even more problematic. Moreover, since for some models the hydrological balance estimates obtained with the runoff fields do not agree with those obtained via precipitation and evaporation, some deficiencies of the land models are also apparent. NCEP-NCAR and ERA-40 reanalyses result to be largely inadequate for representing the hydrology of the Danube river basin, both for the reconstruction of the long-term averages and of the seasonal cycle, and cannot in any sense be used as verification. We suggest that these results should be carefully considered in the perspective of auditing climate models and assessing their ability to simulate future climate changes.Comment: 25 pages 8 figures, 5 table

Direct Economic Impact Assessment of Winter Honeybee Colony Losses in Three European Countries

Honeybees are of great importance because of their role in pollination as well as for hive products. The population of managed colonies fluctuates over time, and recent monitoring reports show different levels of colony losses in many regions and countries. The cause of this kind of loss is a combination of various factors, such as the parasitic mite Varroa destructor, viruses, pesticides, management practices, climate change, and other stress factors. Having in mind that the economic aspect of honeybee colony losses has not been estimated, a pioneer effort was made for developing a methodology that estimates the economic impact of honeybee colony losses. Winter loss data was based on 2993 answers of the COLOSS standard questionnaire survey of honeybee winter colony losses for 2016/2017. In addition, market and financial data were used for each country. In a comparative analysis, an assessment on the economic impact of colony losses in Austria, Czechia, and Macedonia was made. The estimation considered the value of the colonies and the potential production losses of the lost colonies and of surviving but weak colonies. The direct economic impact of winter honeybee colony losses in 2016/2017 in Austria was estimated to be about 32 Mio; in Czechia, 21 Mio; and in Macedonia, 3 Mio. Economic impact reflects the different value levels in the three countries, national colony populations, and the magnitude of colony losses. This study also suggests that economic losses are much higher than the subsidies, which underlines the economic importance of honeybees for the agricultural sector

Hydrological cycle in the Danube basin in present-day and XXII century simulations by IPCCAR4 global climate models

We present an intercomparison and verification analysis of 20 GCMs (Global Circulation Models) included in the 4th IPCC assessment report regarding their representation of the hydrological cycle on the Danube river basin for 1961–2000 and for the 2161–2200 SRESA1B scenario runs. The basin-scale properties of the hydrological cycle are computed by spatially integrating the precipitation, evaporation, and runoff fields using the Voronoi-Thiessen tessellation formalism. The span of the model- simulated mean annual water balances is of the same order of magnitude of the observed Danube discharge of the Delta; the true value is within the range simulated by the models. Some land components seem to have deficiencies since there are cases of violation of water conservation when annual means are considered. The overall performance and the degree of agreement of the GCMs are comparable to those of the RCMs (Regional Climate Models) analyzed in a previous work, in spite of the much higher resolution and common nesting of the RCMs. The reanalyses are shown to feature several inconsistencies and cannot be used as a verification benchmark for the hydrological cycle in the Danubian region. In the scenario runs, for basically all models the water balance decreases, whereas its interannual variability increases. Changes in the strength of the hydrological cycle are not consistent among models: it is confirmed that capturing the impact of climate change on the hydrological cycle is not an easy task over land areas. Moreover, in several cases we find that qualitatively different behaviors emerge among the models: the ensemble mean does not represent any sort of average model, and often it falls between the models’ clusters

Spatial clusters of Varroa destructor control strategies in Europe

Publication history: Accepted - 18 May 2022; Published online - 29 June 2022Beekeepers have various options to control the parasitic mite Varroa destructor in honey bee colonies, but no empirical data are available on the methods they apply in practice. We surveyed 28,409 beekeepers maintaining 507,641 colonies in 30 European countries concerning Varroa control methods. The set of 19 diferent Varroa diagnosis and control measures was taken from the annual COLOSS questionnaire on honey bee colony losses. The most frequent activities were monitoring of Varroa infestations, drone brood removal, various oxalic acid applications and formic acid applications. Correspondence analysis and hierarchical clustering on principal components showed that six Varroa control options (not necessarily the most used ones) signifcantly contribute to defning three distinctive clusters of countries in terms of Varroa control in Europe. Cluster I (eight Western European countries) is characterized by use of amitraz strips. Cluster II comprises 15 countries from Scandinavia, the Baltics, and Central-Southern Europe. This cluster is characterized by long-term formic acid treatments. Cluster III is characterized by dominant usage of amitraz fumigation and formed by seven Eastern European countries. The median number of diferent treatments applied per beekeeper was lowest in cluster III. Based on estimation of colony numbers in included countries, we extrapolated the proportions of colonies treated with diferent methods in Europe. This suggests that circa 62% of colonies in Europe are treated with amitraz, followed by oxalic acid for the next largest percentage of colonies. We discuss possible factors determining the choice of Varroa control measures in the diferent clustersOpen access funding provided by University of Graz. The authors have no relevant financial or non-financial interests to disclose. COLOSS and its supporters had no influence on the study design or the decision to publish

Outcome of the workshop

On 4th and 5th of February 2014, 18 researchers from 13 countries attended the workshop in Graz, Austria. The workshop was supported by COLOSS, University of Graz, the Dean of the Faculty of Science and the Austrian Research Association. An authorized questionnaire that was drafted before the workshop was finalised during the workshop after necessary extended discussion. The questionnaire will be published on the COLOSS website to make it available to all interested countries. Deadlines and important dates for the 2014 monitoring and submission of data were established. The use of additional databases (meteorological and land use) which could be relevant for better understanding of the past and future loss data collected using the COLOSS questionnaire was explored, with input from specialists from other fields. So far only winter losses have been considered, however in southern countries summer losses appear to be more important. This issue was discussed and a decision was taken to further explore summer losses in specific southern areas ideally using a randomized approach. The general feeling was that the monitoring group currently acts as an European entity which attracts other countries, but which may require to develop a stronger European profile. For COLOSS, it would be a good initiative for similar entities to be developed independently in other continents by honey bee researchers based in those continents. Further exploration of specific requirements and conditions is needed. The issue of compliance with the EU regulations on data protection was discussed for future implementation. A jointly authored publication on winter 2012-2013 colony losses which is in press and soon to appear in the Journal of Apicultural Research was welcomed by the participants of the workshop and would be accompanied by an IBRA press release to publicise this article

Outcome of the workshop : C.S.I. Pollen – training the national agents in Graz

On 6th and 7th of February 2014, 26 researchers attended a workshop in Graz, Austria. The workshop was supported by COLOSS, the University of Graz and the Dean of the Faculty of Science. Pollen is the only source of proteins for honey bee colonies and is needed to feed brood, for organ development of adult honey bees and build-up of reserves to become long lived winter bees. All participants welcomed the initiative and agreed that the pollen nutrition of honey bees is of great importance for colony health and survival, and needs to be adequately studied. A means to study the biodiversity of pollen in the supply of honey bee colonies on a large scale is through the involvement of beekeepers as Citizen Scientists (C.S.). As beekeepers cannot perform full palynological analyses, we have developed a simple estimation of pollen diversity according to the colour of corbicular pollen pellets. This allows us to obtain information on a large number of samples, but also requires standardized protocols in all participating countries. National coordinators from the following countries agreed to conduct a common investigation in 2014 and 2015 using the protocols developed for C.S.I. Pollen in pilot studies in 2013: National coordinators of the following countries were present: Austria, Croatia , Denmark, England, France, Ireland, Italy, Netherlands, Norway, Romania, Scotland, Slovenia, Spain, Sweden, Switzerland and Wales. We will re-evaluate the protocols after one year, and also invite other countries to join. As a second step, samples collected by the beekeeper can be analysed to connect pollen diversity derived from colour differentiation of pollen pellets, to the number of plant species identified by palynological analysis. The funding for this second level investigation is to be left to the national coordinators. Traditional melissopalynological methods are not as suitable for the analysis of corbicular pollen pellets compared to honey, so standardized methods for this will be developed. The methods of sub-sampling, storage and transport need to be developed. The first level C.S. Investigations in the different countries will be coordinated and data collected for joint analyses and publication