First results hard substrates test
The Wadden Mosaic research continues even in autumn, during strong winds and rain. As the days are getting shorter and the wind stronger, the Wadden Mosaic team is sailing through the western Wadden Sea and checking the cages containing hard substrates. In the western Wadden Sea, these have been installed in the Eijerlandse Gat, the tidal inlet between Texel and Vlieland. Despite the lower temperatures, the research team was able to assess biological growth on the hard substrates in all 42 cages. The remaining 18 cages, in the eastern Wadden Sea, will be visited in two weeks.
Although the full results are not known until after the laboratory analysis, the first visual examinations are already showing promising results. A lot of life has been found, especially on the more complex substrates, such as lumps of wood. For example, in one of these cages the researchers found multiple individuals of the green sea urchin (Psammechinus miliaris): a species that is associated with hard substrates and is not so often observed. Of course, there are also cages on which much less life is found, such as the cages that have been completely sanded in.
These sanded-in blocks are quite difficult to lift from the bottom for further investigation. After several attempts, the crew of the Navicula – a research vessel of the NIOZ – managed to get all the intended cages in the Eijerlandse Gat on board, but it was not easy! As with all fieldwork, something inevitably went wrong here: wind, waves and tide, along with the “cage” infrastructure, managed to temporarily shut down our zodiac engines and rudders. The field team managed to fix this, despite repairs on (and in) the water that resulted in extremely cold hands and some inventive field adjustments.
The researchers involved were therefore pleased to enjoy a few dry, warm days before having to return to sea to visit the cages in the eastern Wadden Sea.