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| Biological water quality of the Lower Danube (IAD 1996); once the heavilly polluted water from the tributaries (red colour) reaches the Danube the pollution is diluted |
Recognising the need to support and coordinate the increasing activities in the fields of limnology, water resources management and protection against pollution in the Danube River Basin, the Viennese Reinhard Liepolt founded the IAD in the frame of the XIII congress of the Societas Internationalis Limnologiae (SIL) held in Helsinki in 1956. This Association made the "iron curtain” semi-permeable for scientific experts of Western and Eastern Europe. In pursuing his goals Liepolt worked with the Austrian Academy of Sciences, the national committees, ministries and scientific institutes, and linked in cooperative activities the Danube scientists from Switzerland, Germany and all the riparian countries downstream to Ukraine.
Investigating damage and negative trends
Today, IAD strives towards innovative steering and coordination of water research in the Danube River Basin, including the implementation of joint projects by scientific representatives of the 13 member countries: Germany, Switzerland, Austria, Slovakia, Czech Republic, Hungary, Croatia, Bosnia-Herzegovina, Serbia andMontenegro, Bulgaria, Romania, Ukraine and Moldova. Its 13 Expert Groups covering all major fields of aquatic sciences promote ecological studies, particularly long-term analyses, to improve the water quality and restore the ecomorphological structure of the Danube. It is crucial for transboundary rivers such as the Danube that analytical methodologies be standardized and that they meet the existing norms ranging from those pertaining to sampling methods, conservation, preparation and measurement of samples down to data processing, evaluation and documentation of results. One of IAD’s main objectives is to investigate the damage and negative trends in the aquatic ecosystem, to develop ecological concepts and models for river management, and to inform the public of the urgency of improvements.
Main research activities for a healthy Danube
Examples of IAD activities that are part of a detailed work program developed in 1997 include:
• elaboration of GIS-based water quality and ecomorphological maps,
• investigation of river sediments contaminated by toxic pollutants,
• application of long- and short-term bioaccumulation tests to monitor contaminant concentration,
• performance of long-term exotic benthos species surveys,
• establishment of macrophyte inventories and studies about ecotones and floodplains,
• development of concepts for the revival of the endangered sturgeons, and
• support of automatic monitoring stations as early warning systems.
In 2000, the IAD published a map of the biological water quality of the Danube
River, based on the saprobic system (the Lower Danube is shown in Figure 1). The
Upper Danube is mainly water class II (moderately polluted), the Middle Danube
class II-III (critically polluted). Downstream of Vienna, large cities and industries
are major sources of nutrients and toxic substances, thus turning the large tributaries
into classes III and IV (heavily to excessively polluted). However, a high discharge
and self-purification capacity of the Danube River keeps the Lower Danube mostly
between class II and III.
Sediment contamination with seven heavy metals was investigated by introducing
a classification system based on the six compartments: filtered river water, untreated
river water, suspended matter and fine-grained sediment, fish muscles, zoobenthic
species, and phytobenthic species (for example lead, Figure 2). Hence, heavy metal
contamination is quantified by using one compartment and extrapolating to the
others. The same colour scheme as with water quality classes can be applied, and
the values can be compared with the threshold values developed by ICPDR in line
with the EU-Water Framework Directive. With the help of these classification schemes
and maps, water authorities can plan measures to mitigate heavy metal pollution
in an optimal and economically feasible way.
The IAD has been monitoring the fauna exchange triggered by the completion of
the Rhine-Main-Danube-Canal in 1992. Many benthos species have since then actively
migrated between the Danube and the Rhine rivers or they have been passively transported
by water or by ships. Alien species of pontocaspian origin have been found as
well as other newcomers that threaten the native populations by competing with
them for food and habitat. Further ecological studies are aiming at macrophyte
mapping and investigations of ecotones, the biologically active zones between
terrestrial and aquatic ecosystems. In particular, biogeochemical cycles, population
structures and biomass production in particular, as well as the structuring of
landscape units were studied in the floodplains of the Danube and the Morava rivers.
Such research leads to an understanding of the ecological function of floodplains
and their role as "hot spots” of biodiversity and, in combination with
hydrological studies, their function as water and nutrient retention areas. Scientists
from Austria´s "Danube Floodplains” and Hungary´s "Gemenc
Beda - Karapacsa” national parks have successfully cooperated on the project.
Under the umbrella of IAD, Romanian ecologists at the institutes of Galati, Tulcea,
and Bucharest have intensified scientific investigations of the Danube Delta restoration
and the protection of the endangered anadromous sturgeons along the Lower Danube,
including the Stellate, the Beluga and the Russian sturgeons. These "living
fossils” are now the flag animal of IAD, and the long-term project "Sturgeon
2020” aims at sturgeon revival along the Danube similar to the successful
Rhine River "Salmon 2000” programme.
IAD scientists also acted as consultants in large and detailed investigations
of the Bavarian Danube tributaries the Naab, the Regen and the Salzach. Two automatic
on-line measurement stations in the River Naab were equipped with continuous biotests
(luminescent bacteria, Scenedesmus algae, Dreissena mussels). In 1997 these two
biomonitoring stations were installed in the River Danube, thus functioning as
early accident warning system at the German-Austrian border (Figure 3). Future
early warning systems are being developed by IAD using genetic methods and biomarkers
to detect sub-lethal effects of organic pollutants and hormone-active substances
on microorganisms and fish respectively.
Towards integrated river management
Beyond the qualitative aspect of water protection, the river morphology providing
habitats for aquatic animals and plants is of crucial importance. Dams and channelization,
above all in the Upper and Middle Danube, have among other effects drastically
changed the natural hydrological regime, disrupted the river´s longitudinal
continuum, enhanced riverbed erosion and disconnected the riparian zones and floodplains.
These technical impacts have led to a decrease in biodiversity and fish stocks
as habitats were destroyed and migration was disturbed. Hence, IAD is promoting
a basin- wide, integrated river protection strategy by providing a sound scientific
basis for the river managers aiming at a morphological integrity of riverine ecosystems.
Since the EU accession countries in the Danube River Basin need to fulfil the
EU environmental standards, all the activities of IAD are in line with the EU
Water Framework Directive and other EU directives. By actively participating as
observer in the ICPDR, IAD bridges the gaps between basic and applied science,
thus contributing to the implementation of ecological measures in the Danube River
Basin. The ultimate goal is achieving a "good ecological status” of
the rivers, the ultimate requirement of the EU Water Framework Directive.