This is from a webpage.
Twitter user Tara Neilson shared photos of the orca while it was
stranded. It appeared to be lodged in seaweed-slicked rocks.
I wonder what ‘seaweed-slicked’ means in the above context.
My sense is that it means ‘covered with seaweed and having a smooth surface’.
Am I right?
The Free dictionary defines slick as "smooth, glossy, and slippery". It means the rocks have been made slick by the seaweed. This is presumably because they are covered with seaweed, as you suggested. "Slick" would have been used because of their slipperiness.