ed lavandera has that story. >> reporter: this is a rather interesting mission that scientists from the university of south florida have just returned from. they spent ten days on the water. they say for the first time they found toxic levels in the water that was doing damage to some of the very basis of the food chain in the gulf of mexico. i'm sorry, ali. i thought we were going to have the story there. but the scientists just returned late last night from that mission, ten days. they went through an area that was north, northeast of where the deepwater horizon spill site is. and one of the things that they found, three things in particular they say stood out to them, one being that they found oil micro droplets all along the