With festive costumes and 13 site-specific, environmentally themed performance-art pieces, the Hudson River Pageant wended its way along the Lower West Side waterfront Saturday. Events included a live-fish release, oyster planting, river cleansing and a “dance” of kayaks and Whitehall rowboats with a harmonic chant. The pageant’s goal is to restore the river’s endangered species and habitats and to address climate change.