The EcoSCOPE is an optical sensor system deployed from a small remotely operated vehicle (ROV) or fibre optic cable to investigate behavior and microdistribution of small organisms in the ocean. Although the ROV is very small and quiet it is impossible to approach feeding herring closer than 40 cm. From this distance, however, their prey copepods in front of the herring are invisible due to the deflection of light by phytoplankton and microparticles in highly productive waters where herring live.

By imitating the long and thin snout of the garfish protruding into the security sphere of the alert herrings, an endoscope with a tip diameter of 11 mm is used. The endoscope is camouflaged to reduce the brightness-contrast against the background: the top is black and the sides are silvery. Additionally, the front of the ROV is covered by a mirror, reflecting a light gradient resembling the natural scene and making the instrument body virtually invisible to the animals. The ecoSCOPE allowed observation of feeding herring from a distance of only 4 cm. The predators are illuminated by natural light, the prey by a light sheet, projected via a second endoscope from strobed LEDs (2 ms, 100% relative intensity at 700 nm, 53% at 690 nm, 22% at 680 nm, 4% at 660 nm, 0% at 642 nm). A second sensor is imaging other copepods, phytoplankton and particles at very high magnification. Another advantage of these small "optical probes" is the minimal disruption of the current-field in the measuring volume, allowing for less disturbed surveys of microturbulence and shear.

Video (50 %, looping, each image shifted to compensate the rolling microturbulences from the waves) of feeding juvenile herring (38 mm) on copepods - the fish approach from below and catch each copepod individually. In the middle of the image a copepod escapes successfully to the left

Another video is mounted on the pages for Atlantic herring

An ecoSCOPE was also deployed to measure the dynamics of particles in a polluted estuary: see image on Particle (ecology), another as an underwater environmental monitoring system, utilizing the orientation capacity of juvenile glasseel :

It is a product of the new initiative of "Ocean Online Biosensors": a synthesis of IT-sensoric and the sensing capability of ocean organisms. It is the opinion of many scientists that eels developed the finest nose of the planet. They can sense concentrations of one part in 19 trillion. This is the same concentration as one glass of alcohol in the waters of all Great Lakes.

Depicted on the image is the central-unit. On all four corners are little entrances, through which water from different sources enter (rivers and creeks in New Jersey). It flows through a small labyrinth and mixes in the central chamber. It exits through a small tube in the middle. The glasseels migrate through this small tube heading into the current. In the middle is the entrance for the eels. They test the different Water qualities and migrate towards the corner, where they exit. For the eels the sensoric impressions are probably as diverse as the colors visible for us. The system is submerged, and a digital camera observes the exits. The software package dynIMAGE (sponsored by VOLKSWAGEN STIFTUNG ) monitors the frequency of decisions per exit. Many thousand of glasseels pass through the system on a single day. The three exits in the left lower corner carry water from polluted sources (one is a drinking water reservoir). EcoSCOPE systems raised already quite some turbulences (on the political level, tracking water pollution and its effect on fish and plankton behavior in Europe and USA). For many months systems have been online, and for the future it is anticipated to deploy ecoSCOPEs contineously online, within the project LEO Projekt off New York, visible for all. Tests have also been performed with different qualities of drinking water and with solutions of runoff juice from different samples of meat (fish).

Short movie of migrating glasseels : Glasseelu.mov

Detail of the mixing chamber - Closeup on the migrating glasseels - visible through the transparent skin are the gills and the heart

The little tube extending from the nose is visible

See also: American eel and Eel story

External links

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