Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Commission research helps identify causes of loss of wildlife in the Baltic Sea in summer 2002

18.09.2003


The dramatic loss of marine wildlife recorded last year in the Western Baltic Sea between Denmark, Germany and Sweden is largely the result of extreme weather conditions and an increase in man-made nutrients, according to the findings of a report recently released by the Helsinki Commission (HELCOM), to which the European Commission provided significant input. Last autumn, the two organisations joined forces to investigate exceptional oxygen depletion in the Western Baltic that had led to hundreds of dead fish being washed ashore along the east coast of Jutland, Denmark. The report reveals that the oxygen deficiency was caused in part by heavy rain and snow, leading to the run off of higher levels of nutrients from agriculture, urban wastewater and air pollution into the sea. In addition, low wind levels and high air pressure minimised exchanges between different water levels in the Baltic. The report recommends stricter controls on nutrients reaching this inland sea to prevent future oxygen depletion.



Research Commissioner Philippe Busquin said: “We must do more to reduce the level of man-made nutrients polluting the Baltic Sea and the destruction of its precious ecology. We cannot ignore nature’s alarm calls, and must ensure that our research findings help shape appropriate international policies.”

A preliminary version of the report was used in the preparatory work for the HELCOM Ministerial Meeting, which took place on 25th June 2003 in Bremen. Environment Commissioner Margot Wallström participated at this meeting on behalf of the European Commission. A wide-ranging package of measures for the protection of the Baltic marine environment was agreed upon by the Ministers. With regard to combating eutrophication , this package included the following agreements to:

  • make agriculture more environmentally sustainable;
  • ensure that EU directives such as the Nitrate and Urban Waste Water Directives are fully implemented;

  • improve agricultural practices to ensure efficient use of nutrients while minimising any adverse impact on the environment;
  • reduce pollution by nutrients from other sources.

Tackling a wildlife disaster

Widespread and long lasting severe oxygen depletion was observed in the Kattegat, the Sound and the Baltic Sea in late summer and autumn 2002 – amongst the worst ever recorded. In several areas, extreme oxygen deficiency led to the release of highly toxic hydrogen sulphide from marine sediments. As a result, creatures living near to the bottom of the sea died and, in October 2002, a large amount of dead marine wildlife was washed up on the Jutland coast.

Following the initiative of the HELCOM Monitoring and Assessment (MONAS) Group, an expert group was set up with Denmark, Germany, Sweden and the European Commission to analyse the development and causes of this worrying situation.

Eutrophication is still a major problem in the Baltic Sea. The symptomatic problems of eutrophication – serious oxygen deficiency, extensive algal blooms and floating mats of decaying seaweed in coastal waters – remain all too common, in spite of substantial efforts to reduce nutrient inputs over a wide area. In the EU as well, intensive agricultural methods make farmland a major source of waterborne nutrient pollution.

Analysis of the development and causes of the 2002 oxygen depletion required expertise from several disciplines, including marine biology, oceanography and satellite remote monitoring. The experts formed a Working Group to seek explanations and recommendations for decision-makers.

Identifying the cause


Comparisons between recent years marked by specific weather events in the area revealed the key roles of snow, rain, and wind and air pressure in the oxygen balance of marine bottom waters. The amount of snow and rain largely controls the nutrient loading of surrounding rivers by soil erosion. Unseasonably late rains, combined with sunlight can also indirectly enhance marine plant production in surface waters. Wind and air pressure acts on the local supply of oxygen through water exchanges with the oxygen-rich waters of the Skagerrak.

Field measurements show that in 2002 there was a higher nutrient discharge in the Baltic Sea in June and July as a result of above average rainfall. Microalgae biomass, measured by both traditional means and satellite remote sensing, showed slightly higher levels in July compared with previous years. However, 1999 levels were substantially higher than 2002, yet oxygen conditions were better.

Comparable results from three independent hydrological models (Denmark, Sweden and the Commission) provided the main explanation for particular sensitivity to oxygen consumption in 2002. August was marked by almost no water exchange at the bottom of the sea, between the Skagerak (oxygen-rich) and the Belt Sea area (oxygen-poor), and there was substantially lower inflow than usual in July and from September to November. Deep bottom oxygen depletion (at 15 to 60 metres) resulted from this particular low water exchange, the latter controlled mainly by wind and air pressure above the North and Baltic Seas. In addition, unusually low winds severely limited mixing in surface waters (down to 15 metres) and were responsible for oxygen deficiencies at shallow levels.

Reduced nutrient levels essential

While weather conditions were the main trigger of the 2002 event, investigations revealed that the Baltic Sea is particularly vulnerable to oxygen depletion. Permanent separation of water strata, minimal reaction with the sea bottom, restricted flow patterns resulting from semi-enclosed bays and estuaries and shallow bowl shapes in the sea bottom all favour the isolation of bottom water masses and therefore limit reoxygenation.

The Baltic Sea region is one of the most naturally sensitive to oxygen deficiency in Europe. Some confined regions – such as the Little Belt – were already experiencing oxygen deficiencies 100 years ago, when nutrient discharges were relatively low. For several decades the main original cause of extended oxygen deficiency has been the nutrient supply in surface marine waters.

The Commission contribution indicates that the Belt Sea area has a very limited capacity to digest the organic matter and, indirectly, to assimilate any additional supply of nutrients. Further efforts are necessary to meet the 50% nutrient reduction target set by HELCOM. But even this might turn out to be insufficient to drastically reduce the likelihood of severe oxygen depletion in terms of geographical coverage and duration in the Western Baltic.

Fabio Fabbi | European Commission
Further information:
http://www.dmu.dk/1_om_dmu/2_afdelinger/3_hav/oxdep2002/default.asp
http://ies.jrc.cec.eu.int/Units/imw/
http://www.helcom.fi/

More articles from Ecology, The Environment and Conservation:

nachricht Dune ecosystem modelling
23.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>