environment minister sussan ley said warmi oceans and other factors are killing the corals that make up the reef. >> this reef has suffered in the last few years. bleaching events, and various attacks by the predator crown- of-thorns starfish. so, unsurprisingly, the outlook is that the condition has deteriorated. and the report calls out the biggest threat to the reef, ich is climate change. >> woodruff: the great barwoer reef is thd's largest coral reef system. back in this country: the democratic pcaty effectively eled plans for "virtual e ucuses" in iowa and nevada -- letting people v phone. but tional party leaders sai the system could be vulnerable toacking. and on the republican side: illinois congressman john shimkus announced he will retire. he is the 14th house republican not running again next year, compared with nearly 40 in the 2018 mid-terms. the official account of twitter c.e.o jack dorsey was hacked today, sending out vulgar and racist tweets. twitter quickly deleted the posts, and said it is investigating. the incident may be related to twitter's promise to crack do