By bringing back the kelp, they seek to control the sea. That is the Merman nature: control.
Islanders float with the waves and the winds and the currents. Mermen would control these forces and control us.
Islanders bend with things that might otherwise overwhelm them. They are accustomed to change but grow tired of it. Mermen fight against certain kinds of change - and are growing tired of that.
Now, I come to my view of what Ship did with us. I think it is the nature of our universe that life may encounter a force that could overwhelm it if life cannot bend. Mermen would break before such a force. Islanders bend and drift. I think we may prove the better survivors.
***
We bear our original sin in our bodies and on our faces.
The cold slap of a sudden wave over the side snapped Queets Twisp full awake. He yawned, unkinked his overlong arms where they had tangled themselves in the tarp. He wiped the spray from his face with his shirtsleeve. Not yet full sunrise, he noted. The first thin feathers of dawn tickled the black belly of the horizon. No thunderheads cluttered the sky and his two squawks, their feathers preened and glistening, muttered contentedly on their tethers. He rubbed the circulation back into his long arms and felt in the bottom of the coracle for his tube of thick juice concentrates and proteins.
Blech.
He made a wry face as he sucked down the last of the tube. The concentrate was tasteless and odorless, but he balked at it just the same.
You'd think if they made it edible they could make it palatable, he thought. At least dockside we'll get some real food. The rigors of setting and hauling fishing nets always built his appetite into a monumental thing that concentrates could support, but never satisfy.