Marine sampling techniques
There are many situations in which the naturalist will be able to simply pick
up interesting objects, just at her/his feet. One example for those non-ending treasures
are the foraminifera in the Lopar region on the Croatian island called Rab.
They are true antiques, made some tenths of millions of years before our time.
Typical scenario at Lopar, Croatia (on the island of Rab)
Fossil foraminifera at Lopar
Fossil foraminifera from Lopar,
simply picked up from the ground. It is quite fascinating to see those morphological
details which have been preserved over millions of years. Diameter ca. 2 cm
As avid microscopists we are aware of the fact that the
modern siblings of those fossil foraminifera (though being different, smaller species) can
be picked up from the ground too, but most easily from the ground of the oceans.
Foraminifera are quite common in the sands of shallow sea water bays and their shells
or shell fragments will be present in many romance-driven dry sand collections as well.
Living foraminifera from see sand at Lopar.
Diameter ca. 1mm (i.e. a small fraction of the much bigger fossil counterparts shown above).
Terrestrial tardigrades are no problem to sample as well: we simply pick up
small portions of moss cushions which can be found almost everywhere. Moreover
some marine tardigrades, in particular Batillipes species can be simply shovelled in
from the shoreline, even without making our feet wet. But most of us will think twice
before sampling in deeper water. And there are many places close to the ocean
where swimming might be not possible, e.g. when travelling on a ferry or walking along the bay of a harbour.
So, how should we proceed without snorkling equipment or in the vicinity of a harbour?
The early scientific literature about the investigation
of marine organisms is full of sampling devices. Some of them appear rather primitive
and rude, e.g. when heavy equipment is moved along the ocean ground destroying
a great percentage of the scientific prey before it could be recovered. On the other
hand you will find descriptions of much more sophisticated equipment which might be
able to selectively probe a small sample of water at a given depth. And nowadays
we have robots and electronic devices as well ... but most of this will not
be available for an amateur.
We hoped to get some insight into the philosophy of fishing when taking part
in a tourists' fishing boat tour. It was quite useful in so far as to become
aware of the fact that a lot of cruelty has to happen before a typical fish meal.
Furthermore we have come to appreciate the hard work of the fishermen, in particular
when keeping in mind that an incredibly huge fishing net has to be moved across the sea
for a long time, sometimes with rather modest results.
After this lesson by the true fishermen we were aware that
most of our tardigrade fishing might be destructive as well, the only difference
being in scale - and that we will not be able to visually assess the sampling
damages by means of the bare eye.
In former times scientists took all what they could get out of any medium whether
on earth or on sea, just in order to get hold of as many samples as possible. As late as in the second half of the 20th century
scientists become more scrupulous about marine organisms, too. For example the marine
biologist Wolfgang Luther stated in the middle of the last century that any kind of collecting of marine organisms
should follow some rules. He made clear that e.g. harpooning without subsequent
eating of the fish should be considered as a terrible misbehaviour. And he reminded of
those times when tourists shot at the ocean birds - just for the fun of it. Animal life in general
was merely considered as a commercial quantity, marine life being worth even less when seen from a moral point of view.
Times have changed, so we would like to suggest that you should proceed moderately as well,
even when sampling small marine animals. There are many of them, of course, but does
this fact actually give us the right to kill them?
As we have already reached our usual text and image limit
we have to delay the presentation of our dedicated, deep water
marine tardigrade fishing device and hope for your understanding.
Wolfgang Luther, Kurt Fiedler: Die Unterwasserfauna der Mittelmeerküsten.
2nd ed., Hamburg and Berlin 1967, p. 194 [in German only, sorry].
© Text, images and video clips by
Martin Mach (firstname.lastname@example.org).
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