Ocean drifter
The sky is a mesmerising canvas of cobalt blue. The waters of the Andaman shimmer mysteriously under the sun’s searing rays. Already in the warm azure water, complete with floppy sunhat and what appears to be a net in his hand, is the intrepid young marine biologist leading a small group of enthralled resort guests as they wade further and further from the beach. They too are holding the net-like contraption in their hands, trailing it in the water as if taking an invisible dog for a walk.
Ploughing my feet through the water like a piston, eyes squinting desperately against the glare of the late morning sun, I eventually find myself next to Jonathan, who proceeds to hand me the ‘equipment’ that everyone else is holding.
It’s a plankton net, he explains, an equipment used for collecting samples of plankton in standing bodies of water. Comprising a towing line and bridles (the upper part), nylon-mesh net (middle part and used to filter the plankton in the water sample according to the size of the mesh) and a cod end (lower part, at the end of the funnel. Comes with collecting cylinder and a valve for opening and closing), plankton nets are considered one of the oldest, simplest and inexpensive methods of sampling plankton.
The net can be used for both vertical and horizontal sampling. “We can analyse plankton both quantitively (cell density, cell colony or biomass) as well as qualitatively in water samples from the environment,” explains Jonathan.
Taking slow, measured steps so as not to accidentally step on anything underwater (like a sting ray), the Klang-born biologist adds:”Just drag the net through the water as if you’re walking a dog. Although you can’t see anything, believe me, there’ll be lots of stuff in there for us to analyse later.”
Like children given a new toy, we happily trail our nets, following behind Jonathan like obedient school children. He continues to explain: “The word plankton comes from the Greek word planktos, which means wanderer or drifter. There are two main groups of plankton: Phytoplankton and Zooplankton. Phytoplankton is like the plant plankton, while the zoo plankton is the animal plankton.”
All the plankton are food for fish, which in turn are eaten by other sea creatures, like sharks and seals. The latter are then eaten by larger predators such as killer whales. The baleen whale, the largest mammal on Earth, also eats the plankton. Suffice to say, the plankton food web determines the amount of life in the sea. No plankton, no fish for us humans — or other creatures