PLAQUEMINE — When visitors hit the water in the Atchafalaya Basin near Plaquemine, they get more than a tour of the Louisiana swamp. They also learn why the wetland matters and what it stands to lose.Last Wilderness Swamp Tours, a family-owned operation in business since 2000, aims to go beyond sightseeing. Owner Dean Wilson said he wants visitors to grasp the basin's ecological role and why its preservation remains urgent."The Atchafalaya Basin…