HALIFAX – Scientists will begin probing waters off Nova Scotia in search of a slimy creature they believe is slithering north and could be blanketing some of Canada’s richest fishing grounds. Researchers from the U.S. Geological Survey plan to head out today to a vast area over the Canadian portion of Georges Bank to look for a colony of sea squirts nicknamed the Blob for its icky texture and habit of covering almost everything in its path. ‘Covers the bottom’ “It’s something new. It covers up the bottom and it forms a barrier between fish and what fish feed on,...