Solving the Lasker food paradox to show how ocean life eats and lives

At the 181st Meeting of the Acoustical Society of America, Kelly Benoit-Bird will discuss how sonar or active acoustics can identify biological hotspots in ocean life, revealing the answer to the food paradox in the sea.

Using active acoustics, researchers could analyze returning echoes from sound pulses to find small activity hotspots throughout the ocean. Conventional sampling often misses these, giving rise to the Lasker food paradox proposed in the 1970s, which found that laboratory animals fed the average concentration of ocean food did not survive, despite their ocean-dwelling counterparts doing fine.

"We're using systems much like those used to find the depth of the ocean, but instead of interpreting echoes from the seafloor, we're using more sensitive systems that allow us to map layers of life in the water. What we've found is that animals of all different sizes, from millimeter-long plankton to large predators, are unevenly distributed, and this variation is really important to how life in the ocean functions," said Benoit-Bird.

The presence of concentrated pockets of ocean food and biota, varying by depth and location, suggests animals must find and capitalize on aggregated resources to survive. Higher concentrations of resources reduce the energy they must expend continuously hunting for a steady supply of food.

"For example, if a bucket's worth of popcorn was spread out evenly throughout the volume of a room, and you had to fly around to capture each kernel, you would spend a lot of energy searching and it would be hard to get enough to be full. If instead, the popcorn was all grouped together, the popcorn would be a much more satisfying snack. The amount of popcorn is the same but changing how it is grouped determines whether you end up with a full belly," said Benoit-Bird.

Benoit-Bird expanded by saying that the acoustic tools provide the high spatial resolution and long duration sampling necessary to detail and explore the organismal processes and interactions beneath the ocean surface. To effectively manage marine resources, we must understand how many animals live in the ocean and their distribution.