 C. maenas has the ability to disperse by a variety of mechanisms , including ballast water , ships ' hulls , packing materials ( seaweeds ) used to ship live marine organisms , bivalves moved for aquaculture , rafting , migration of crab larvae on ocean currents , and the movement of submerged aquatic vegetation for coastal zone management initiatives . Thresher et al. found C. maenas dispersed in Australia mainly by rare long @-@ distance events , possibly caused by human actions . 
