Scientists develop ‘free-fall’ biodetectors in water to find plankton

Media New Atlas reported that marine life near the sea is known to be very different from those living in the deep sea. To better understand the differences in these regions, scientists have created a biodetector that can “freely fall” in water. The device was developed by a team from the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution and is called EcoCTD. It is part of an existing class of oceanographic detectors, CTD, which measures the conductivity, temperature and depth of water. They also usually collect water samples, which are then checked to detect life forms such as plankton.

Scientists develop 'free-fall' biodetectors in water to find plankton

Typically, a research ship carrying a CTD must stop and wait because the probe needs to be put into the water to collect data before lifting it up. This limits the geographic areas that can be covered for a certain period of time. There are some types of CTD that can be deployed and recycled without stopping, but the disadvantage of these types of CTD is that water samples cannot be collected. This is where EcoCTD works — it is designed to be used during the travel of a ship, but it also measures the concentration of chlorophyll, the green pigment produced by phytoplankton. The presence of plankton, in turn, suggests that there may be other larger organisms.

As soon as the probe falls into the water, a heavy ring of lead falls into the water at a rate of about 3 meters (9.8 feet) per second. Even when the cable-tied host ship is still cruising in front, this rapid descent allows EcoCTD to reach a depth of 500 meters (1,640 feet) in about two minutes — more than the depth that photosynthesis can occur. The crew then used a crane to lift the detector back to the surface. EcoCTD caught up with it in about 12 minutes, covering a vertical distance of about 500 meters.

Scientists develop 'free-fall' biodetectors in water to find plankton

When the device is traveling in the water, an on-board sensor called EcoPuck emits red and blue light pulses. By analyzing how these light is scattered, the sensor is able to determine how much chlorophyll is present. In addition, another sensor called Rinko III Do can measure oxygen concentrations at different depths, which in turn can be used to estimate how much oxygen any microbiome absorbs.

EcoCTD has been successfully tested in 2018 and 2019 on cruises in the Mediterranean and Atlantic oceans.