SCIENCE REVIEW 1987 - Bedford Institute of Oceanography

Research
Fig. 6 An example of the operation of the underice incubator.
surface during the spring months. Lab
experiments with these animals are difficult
since they are physically disturbed when
removed from their habitat, partly due to
the method of their removal. Figure 8
shows the amphipod collector which was
designed to entrap amphipods and to
accomplish recovery in the most delicate
manner possible. The collector net
mounted on the arm is directed into the
tidal current flow which results in animals
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trapped in a transparent cod end bucket.
As the arm is released in the recovery
position, the neck of the collector net
becomes pinched as the bucket falls to the
vertical position thereby entrapping all the
collected animals. The arm is then recovered
through the ice hole with the animals
still swimming in about one-half liter of
seawater in the bucket.
Knowledge of current direction is
required for the proper orientation of the
Fig. 7 Production profiles measured (one month
apart) with the underice incubator.
amphipod collector net. A current meter
deployable through an ice hole was
designed for this purpose and is shown in
Figure 9. The current vane aligns itself
horizontally in the flow direction while
folding in a vertical position for deployment
and recovery. During operation, the
rotational position of the vane is transferred
to surface and displayed by a mechanical
pointer or measured electronically with a
potentiometer. Flow magnitude is also
measured by mounting an electromagnetic
flow sensor.
Fig. 8 An amphipod collector net used to capture
amphipods at the undersurface.