For Southern California surfers, there's going to be a lot going on this summer—and they may want to keep an eye on more than just the forecast in the coming months. With ocean temperatures rising and forecasters watching the development of El Niño in the Pacific, marine scientists are warning that warmer water could bring an increase in some of the ocean's most notorious residents—including juvenile great white sharks . "We predict it's going to be a very sharky summer," said Dr. Chris Lowe, director of the California State University Long Beach Shark Lab , in recent weeks and months. But there's something else, attracted by the warmer waters, that will be lurking beneath as well. The warning comes as sightings of juvenile great white sharks are already increasing along Southern California beaches.…