The facilities of the Marine Biology department include a 3m straight flume channel and 2 annular flumes of 64cm in diameter each.
The large flume was built in 1995 at the GEOMAR institute in Kiel in the course of the
PhD work of Dr. Barbara Springer. It was developped for the study of the interactions
of benthic organisms, the near-bed flow and the sediment surface. These interactions
are often complex and variable in the field. In a flume channel, the different effects
can however be simulated and studied separately. The main channel has lateral walls
made of acrylic glass and it is 3m long, 40cm wide and 40cm deep. The return pipe has a
diameter of 20cm and contains a cooling system and the flow-driving propeller. The
entire flume channel has a total volume of 360 litres. Depending on the water level and
the gear ratio of the adjustable electrical motor, flow velocities range from 1cm/s to
20cm/s - in exceptional situations even up to 60cm/s. The return pipe surrounds the
test section area laterally in order to allow the insertion of 3 multicorer samples
from below (cf. "Methods: Instruments at sea").
Alternatively, a box rack can be adapted to the test section for
experiments with larger quantities of sediment like e.g. burrowing animals such as the
bivalve Arctica islandica. Ontop of the main channel, a rail system is used to
support different sensors and to move them to any position inside the flume channel.
currently, these sensors are an acoustic Doppler current meter (NorTek ADV) and a
relief scanning laser system. The positioning and data recording are
computer-controlled and can be programmed according to the needs.
More details on the principles of operation
of the ADV and laser scanner are given on an extra page.
Left: Sketch of the flume, right: experiment combining flow measurements
and behavior studies of Balanids.
Sp: sensor positioning unit, Se: flow sensor, ReLa: relief laser, Ts: test section,
Sh: sample holder
Mo: motor, Pp: propeller, Tr: temperature regulation unit, Im: insulating material, G:
collimator grid
Two annular flumes made of acrylic glass were built in 2001 during the project DYNAS. They are designed to measure changes in seston concentration or chlorophyll, linked to filtration or resuspension by benthic organisms, within a smaller water volume than the large flume. The flumes have an outer diamater of 64cm and an inner diameter of 40cm. Between these walls, the actual channel is 12cm wide and it has a surfac area of 0.2 square metres. With a sediment layer of 10cm, the water volume is 66 litres for each flume. The flow is generated with a submerged rotating ring (adjustable 12V electrical motor) of acrylic glass which entrains the water. Five valves situated along the outer side wall are used for water sampling purposes.
Annular flume setup with sediment and observation camera