To hear Anne Seelbach talk about the painting, stencils, and bas-relief collages she’s been doing recently — “to bring awareness of the effects of industrial and chemical pollution on the marine environment” — one might easily conclude that she has become political, but it is not the case. “I am first an artist, not an activist,” she said at her Sag Harbor studio, adding, however, that “it is also true that I hope to bring awareness to nature as I see it.”