Expedition Tohoku
A team of European and Japanese scientists embarked on a Japanese scientific research cruise on R/V Tansei Maru (Fig.) to investigate the impact of the tsunami on the marine ecosystem and recovery of the seafloor environment following the tsunami. From the Netherlands a team from Utrecht University (Dr. Gert-Jan Reichart, Dr. Karoliina Koho and Dr. Lennart de Nooijer) joined the expedition. They specifically targeted changes in the chemical conditions at the seafloor, which will be related to the eclogical community structure, and later via trace metal analyses of the foraminiferal shell look at the long term effects.
Video
Blog
Read the blog of Dutch scientist about the Expeditie Tohoku:
Day 1: First glimpse of the ship
Day 2: Sailing outDay 3: Sampling low-oxygen stationsDay 4: Found the Tsunami deposit?
Ecological impact of the Japan earthquake
Friday March 11th 2011, Japan was struck by one of the most powerful earthquakes in the country’s history, measuring up to magnitude 9 on Richter scale. This earthquake triggered a massive tsunami wave devastating the coastal areas and resulting in the Fukushima nuclear power plant disaster. The extensive devastation on land is evident, but to what extend the underwater world was affected by the event is still unknown but most likely also widespread.
Impact on the marine ecosystem
A team of European and Japanese scientists embarked on a scientific research cruise on R/V Tansei Maru (Fig.) to investigate the impact on the marine ecosystem and recovery of the seafloor environment following the tsunami. The team studied benthic foraminifera, microscopic unicellular organisms that are abundant in all marine setting.
Foraminifera as 'recorders' of their environment
Foraminifera (Fig.) are sensitive recorders of the ambient environment, different species having their own ecological niches. Due to the opportunistic nature of some species, environmental changes are quickly observed in the community structure and composition.
Furthermore, additional information can be gained through chemical analyses of the foraminiferal calcite shell. The trace metal content of the foraminiferal shell can be related to in situ growth conditions, like temperature, salinity and oxygenation.
Image captions
Fig. 1: Sediment sampling for pore water and sediment chemistry. Changes due to massive sediment transported such as possibly associated with tsunamis can be reconstructed this way. From the same cores the sea floor fauna will be investigated
Fig 2: Scanning electron microscope picture of benthic foraminifera Uvigerina mediterranea. These foraminifera can be used as very sensitive recorders of 9transient) changes in the environment at the sea floor. Both their relative abundances and changes in their test chemistry will be studied in relation to the tsunami.