The Story: "Earth's Final Hour!" by Mike Friedrich, Dick Dillin, and Joe Giella. The story opens with...yes, Aquaman!--Aquaman discovering that all the plankton on the ocean floor is being stripped away.
As he tries to discover why this is happening, a mysterious figure hits a button on a machine causing a rock slide, crushing Aquaman, but note before hitting his JLA transmitter.
We then flash back to the story of our bad guy, named Theo Zappa(!), whose inventions made him a billionaire industrialist(I wonder if Bruce knows him). His ultimate goal, though, is to run the world, of course! He is met an by an alien named Panja Darr who asks him for help, since his world has destroyed all of its plankton due to pollution, and asks Zappa to build an invention to take it from Earth and give it to them. Zappa agrees, but secretly decides to play both ends against the middle.
Anyway, we go back to the JLA, who are responding to Aquaman's signal. He explains to them that without plankton for sustenance, all the fish in the world will go mad, then beach themselves and die, leading to a chain of events that could destroy the world! Arthur is a real glass half-empty kind of guy.
The teams of Superman and Aquaman, and Hawkman and Flash, are stymied by Zappa's machines, but when Batman and Atom investigate Zappa's lab, they run into the alien who started all this in the first place. He has discovered Zappa's true plan(to "hold" the plankton hostage, blackmailing both worlds) and asks our two heroes for help.
The Atom decides its his skills as a scientist that are needed, and reverts back to being Ray Palmer to examine the machine that Zappa is going to use for his plan. They need a power source for it, and Darr tells them they have some on their planet, so they teleport to it, where Zappa has already declared himself the boss! Luckily, even with some cockamamie ray gun, he's no match for them, and Atom knocks him out.
It's now up to the JLA--Superman specifically--to talk to the people of this world and tell them what has happened, and that they have to save their own planet from their own short-sightedness, not simply poach from another world. Superman offers them temporary help, but also they must come up with their own plan to save their world...just like Earth does!
Roll Call: Superman, Batman, Aquaman, Flash, Atom, Hawkman
Notable Moments: Of course, it's great to have Aquaman back. In Michael Eury's super-fun JLA Companion book(Volume One), he asks Friedrich why Aquaman was back, after being out entirely during O'Neil's run. No big mystery, Friedrich just figured, hey, he's a member, why not use him? This AquaFan thanks you, Mike!
This issue has an unusual ending, what with with Superman's sober speech about pollution rather than having him whip up some Super-Solution. Denny O'Neil is listed as "Script Consultant" and at the end Neal Adams is thanked for his special help with this story.