Daily Green: As every one who has ever strapped on a snorkeling mask or flipped the channel to an undersea nature program knows, the oceans are a wondrous and diverse place, filled with colorful creatures in sometimes otherworldly shapes, all involved in life-and-death darting dances, strange mating displays and awe-inspiring long-distance migrations. But the future of the oceans is the past, with that vast and beautiful diversity reduced to a stew of jellyfish, bacteria and toxic algal …