In the episode, Laura and Justin transform themselves into a pair of dolphins and explore the waters of Shark Bay, Australia to figure out what happened when a mysterious heatwave wreaked havoc on the local dolphin population.

Rising ocean temperatures pose a serious threaten to marine species, including dolphins. A seemingly innocent, short-term rise in ocean temperature off the west coast of Australia had devastating and long-term consequences for a number of plant and animal species in Shark Bay. The local population of Indo-Pacific bottlenose dolphins saw a drop in their population numbers, as well as low birth rates after the heatwave. Eight years later, the population is slowly recovering.

The article being discussed in this episode is:

Sonja Wild, Michael Krützen, Robert W. Rankin, William J.E. Hoppitt, Livia Gerber, Simon J. Allen. Long-term decline in survival and reproduction of dolphins following a marine heatwave. Current Biology, 2019; 29 (7): R239 DOI: 10.1016/j.cub.2019.02.047

Here's a link to more info about the article article:

https://www.sciencedirect.com/science/article/pii/S0960982219302179