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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.

[ Lopar, Rab island, Croatia ]

Typical scenario at Lopar, Croatia (on the island of Rab)

[ Fossil foraminifera at Rab ]

Fossil foraminifera at Lopar

[ Macro view ]

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 Lopar ]

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.

[fishing 1]

[fishing 2]

[fishing 3]

[fishing 4]

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  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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