|Ballast water: an investigation into the presence of plankton organisms in the ballast water of ships arriving in Dutch ports, and the survival of these organisms in Dutch surface and port waters|
Wetsteyn, L.P.M.J.; Vink, M. (2001). Ballast water: an investigation into the presence of plankton organisms in the ballast water of ships arriving in Dutch ports, and the survival of these organisms in Dutch surface and port waters. Rapport RIKZ = Report RIKZ, 2001(26). Ministerie van Verkeer en Waterstaat. Rijksinstituut voor Kust en Zee (RIKZ): Middelburg. 71 pp.
Part of: Rapport RIKZ = Report RIKZ. Rijksinstituut voor Kust en Zee (RIKZ): s-Gravenhage. ISSN 0927-3980, more
Ballast; Ecological crisis; Harbours; Marine organisms; Plankton; Public health; Marine; Brackish water
|Authors|| || Top |
- Wetsteyn, L.P.M.J.
- Vink, M.
The world-wide transport of ballast water has been shown to be an effective distribution vector for numerous non-native organisms. Discharge of this ballast water may lead and has led to the introduction of these organisms into all kinds of fresh, brackish and seawater environments. In many cases, these unintended introductions had serious economic, ecological or public health consequences.The International Maritime Organization is developing regulations to tackle the ballast water problem. To define a Dutch point of view, the North Sea Directorate of the Ministry of Transport, Public Works and Water Management, initiated a number of ballast water studies. The objectives of this ballast water study were to answer the following questions: 1) which organisms are imported with ballast water in ships arriving in Dutch ports? and 2) do these organisms survive in Dutch surface and port waters?During the period November 1998 -November 2000 ballast water samples were taken on board of 30 ships (container ships, multi- purpose ships, chemical tankers and bulk carriers) in the port areas of Rotterdam, Amsterdam and Vlissingen. In most cases the investigated ballast water was taken up in European ports or estuaries, but also mixtures of estuarine and oceanic waters were sampled. The temperatures of ballast water almost always differed by a few degrees from those of port water. Most of the sampled ballast water originated from brackish and seawater environments; port water samples almost always could be classified as brackish.A large number of plankton species was found in the analysed ballast water samples. The number of phytoplankton species and cell numbers increased significant I y when the residence time of the ballast water in the tanks had been shorter. In the analysed ballast water samples a conservative distinction was made between species analysed to species- genus or group level. 122 phytoplankton species (mainly diatom and autotrophic dinoflagellate species), 37 microzooplankton species (mainly heterotrophic dinoflagellate and rotifer species) and 12 mesozooplankton species (cladoceran and copepod species) were determined to species level. Most species were known already from the Dutch phytoplankton monitoring programme, from other programs and from literature. Only 3 non-native dinoflagellate species were found in the ballast water samples. Furthermore, we found diatom, bluegreen and dinoflagellate species with recorded toxic effects on humans and animals, in 6 to 19% (depending on the species) of the investigated ballast tanks.In the analysed port water samples, 72 phytoplankton species (mainly diatom and autotrophic dinoflagellate species) and 17microzooplankton species (mainly heterotrophic dinoflagellate species) were determined to species level. Mesozooplankton species were not recorded because of the small sample volume.Incubation of ballast water at temperatures of 10 and 20 °C in different media and in filtered port water with salinities of 0.3 to 30 psu, always resulted in growth of approximately 5 to 20 phytoplankton species.Also a few potentially toxic phytoplankton species, that were observed in the ballast water samples, grew in the media used. A significant relation between the number of growing species and difference in salinity (salinity of the medium used minus the salinity of ballast water) was not found, very probably because of the large salinity tolerance range of phytoplankton.Obviously, many living plankton species are imported with ballast water into Dutch ports, including unwanted non-native, toxic and potentially toxic phytoplankton species. After the ballast water is discharged, part of the imported organisms is able to survive in Dutch surface and port waters. We sampled only a very small fraction of ballast water on board of each ship. Extrapolating our results to the scale with which ballast water is discharged in Dutch surface and port waters, we may assume that unwanted species are released in large numbers into these waters. If these species are being released regularly and in large numbers, there is a great chance of interfacing with specific abiotic conditions, such as a great river run-off for example. that may favour these unwanted species. In summary, ballast water discharged into Dutch ports. is certainly not free from risks, such as, for example, the growth of non-native, toxic or potentially toxic phytoplankton species.