Settlement success of the blue mussel Mytilus edulis on artificial substrates
The Bay of Jade (see Fig. 1) near the city of Wilhelmshaven, aroused by tremendous storm tides during the 13th and 16th century, is characterised by strong tidal currents and high tidal ranges combined with enormous changes in salinity during one tidal cycle. Due to the existents of large natural beds of blue mussels, highest larval concentrations are recorded every spring. But, because of the morphological situation, water exchange of the Bay is week, leading to high concentration of macro parasites and to high infestation rates of mussels. Therefore commercial on-bottom culture of mussels was stopped, by official orders. In the Jade-Project running since April 2006 blue mussels (Mytilus edulis) are cultivated under near-shore conditions. The aim of the project is, to compare all analysed relative parameters (e.g. settlement success) with those found by offshore grown mussels from the area of Nordergründe (see MytiFit-Project) and ODAS (see AquaLast-Project).
In cooperation with the port authorities (NPORTS) of Lower Saxony a cargo bridge (see Fig. 2), for the coal supply of a nearby power plant, is used to test mussel spat collectors of different style and surface material (see Fig. 3 & 4). Analogue to the MytiFit-Project the focus of investigation are the settlement success and attachment strength of mussels using different artificial substrates, the shell stability, the loads of micro and macro parasites (analysis in cooperation with LAVES) and the lysosome membrane stability of the digestive gland cells as an indicator of the overall energy status of the mussel (analysis in cooperation with the International University of Bremen, IUB). Samples are taken monthly from long collector ropes (see Fig. 5) fixed at a service pontoon under the cargo bridge (see Fig. 6 & 7).
In close cooperation with the Universities of the region this project is fully organised by Bachelor or Master students supported by technicians from the AWI (see Fig. 8 & 9).