HUNTINGTON BEACH, Calif. (AP) — After a crude oil sheen was detected on the waters off the Southern California coast, environmentalists feared the worst: A massive spill that would wreck the ecosystem. A week later, the region and its signature beaches appear to have been spared a potentially calamitous fate, though the long-term toll on plant and animal life remains unknown. “Based on what we’re seeing, it’s a lighter impact than expected of a worst-case discharge,” California Fish and Wildlife Lt. Christian Corbo said. Officials initially feared Huntington Beach — dubbed Surf City USA — could be off-limits to surfers and swimmers for months. But Mayor Kim Carr on Thursday said she was “cautiously optimistic” they could be back in the water in weeks.