The LO/KPOJ "Lost Limerick Challenge"

This morning's Oregon news limericks, as written by me, read by quizmaster TJ of Loaded Orygun, and answered (usually) by Carl, Christine,and Paul on the KPOJ 620AM Morning Show, are posted at LO.

And once again p3's Literary R & D department ended up with an extra limerick that didn't make it on the air, so you can play along at home. Fill in the blank with the word or phrase from this week's Oregon news:

First, sea creatures were there--then they weren't.
Because nutrients, once there, now eren't.
There's a place off the coast
Where marine life is toast--
Due to shifts in the earth's _____________ .

(The answer can be found in the Comments below, or in this week's Spanning the State at Loaded Orygun.)