Sea of Pearls — Elaine Lowe

Standalone sequel to Seeds of Garnet.
 
After a company shakeup, cast-iron bitch Ivani Gorl finds herself powerless and on the edge of a nervous breakdown. Time for rest and relaxation. Saving Lake Silith on planet Lithos presents a beautiful challenge.
 
Hydrologist Garom Sesh is also at the lake. But he doesn't just live for the water, he breathes in it. A merman, Garom resents being chained to this planet. Though the water is silky, the pearly pebbles stuck in his gills are driving him mad!
 
Nothing lots of steamy, wet sex won't fix. And Ivani is more than willing to work very, very closely with him.