How much life passes through one cubic foot of water in the San Francisco Bay every day? Photographer David Liittschwager set out to answer that question over the course of 14 days this past spring. From a small sailboat anchored in the shadow of the Golden Gate Bridge, he and a team of scientists collected and photographed whatever plants and animals were carried by the bay’s currents into a metal square-foot cube submerged in the upper water column.

The sounds and smells of the bustling Coliseum swap meet—frustrated honking from the overcrowded parking lot and the hot fried dough aroma of fresh churros—drifted over Seminary Creek Saturday morning, as volunteers clad in neon-yellow work vests trolled its steep banks looking not for a bargain, but for trash.