Artist Meghann Riepenhoff works primarily as a photographer, yet you’d never know it watching her make pictures on a recent morning at Rodeo Beach — without a camera, film or need of a darkroom. She unfurls yards of chemically treated paper at the crashing surf’s foamy edge, submerges it in the water, then runs back up the sand, working quickly to lay out the wet sheets on a tarp, weighting them with found rocks before scattering sand on their surface.