Scientists say they’ve seen disturbing new signs that the ailing Salton Sea is entering a dangerous phase. Biologists Chris Schoneman and Tom Anderson of the Sonny Bono Salton Sea National Wildlife Refuge say it appears reproduction might be stalling for a once-hardy fish species. Meanwhile, some birds that normally flock to the lake are nowhere to be found. Schoneman and Anderson say this could signal a long-anticipated tipping point in the ecosystem at California’s largest lake.