"There is no romantic adventure or skullduggery at work here," said Professor Fred Dobbs from Old Dominion University, Virginia, USA. Ships pump water in and out of ballast tanks to adjust the waterline and compensate for cargo loading, making the ship run as efficiently as possible. These tanks can hold thousands of tonnes of water. "Any organisms in the water are likely to be released when it is next pumped out."
Many non-native animals and plants have been taken to new environments and become invasive, threatening the survival of local species; some fundamentally alter the ecosystem. Zebra mussels were introduced in North America and the comb jelly in the Black Sea and both have had enormous ecological and economic impacts.
For more than 20 years we have known that a variety of large phytoplankton and protozoa are transported in this way, but we know very little about smaller microbes like bacteria and viruses. "It is inevitable that hundreds of trillions of micro-organisms enter a single ship's ballast tank during normal operations," said Professor Dobbs. The majority of these microbes are harmless, but some are a potential risk to public health.
"Vibrio cholerae, which causes cholera in humans, can be carried in ballast tanks," said Professor Dobbs. "There have been no known outbreaks of disease associated with ballasting activities, but the water is only sampled very rarely." Other disease-causing microbes in the tanks include Cryptosporidium parvum and Giardia duodenalis, which cause stomach upsets.
Some people say microbes are present everywhere; they may be easily dispersed because they are so small. However, many experts believe micro-organisms have a "biogeography", a natural home, which means they could become invasive if moved and have a negative effect on different environments. There is some evidence for this argument: two phytoplankton species called diatoms were introduced to the English Channel from the North Pacific Ocean
The International Maritime Organisation, which sets rules and standards for the global shipping industry, has proposed an upper limit to the numbers of Vibrio cholerae, E. coli, and intestinal enterococci contained in discharged ballast water. A few ships are also using different treatments to reduce and even eliminate the microbes in their ballast water. "A number of techniques are being looked at for this purpose, from filtration to biocides, ultrasound to ultraviolet irradiation," said Professor Dobbs. "Our understanding of the issues involved will increase as more studies are carried out, particularly those employing the tools of modern molecular biology."
Lucy Goodchild | alfa
Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory
How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy