The biggest migration happens every night in the ocean. Plankton come up from the twilight zone to eat, safe from daytime predators. And then they go back to the deep ocean before dawn. Debbie Steinberg says that these plankton are helping us to manage our carbon output by taking it back to the deep ocean. And: The rustic boardwalk that winds through the marsh carrying visitors down to the water’s jagged edge at Ragged Island is getting shorter. Due to erosion, two feet of the boardwalk has been cut back each year for the past twenty years. Rob Atkinson and Gary Whiting say it won’t be a generation before homes are threatened and the biodiversity and carbon storage would be lost. They’re working with students to try to divert that unfortunate outcome.

Later in the show: As sea levels rise, groundwater in coastal areas is getting saltier. This has been a real issue for farmers because many things don’t grow well in salty water. But some do -- and that could mean a new specialty crop. Josh Dusci is testing the hypothesis that tomatoes grow sweeter in saltier water. Plus: For years, the United Kingdom and Germany had used Icelandic waters for fishing. But when Iceland became an independent nation, its leaders realized they’d need the economic benefits of their own waterways to sustain themselves. So they claimed exclusive rights of fishing in their waters. Ingo Heidbrink walks us through the three big conflicts of the so-called Cod Wars.