(By Bruce Henderson, bhenderson@charlotteobserver.com) Gold prospectors chasing $1,600-an-ounce flecks in river bottoms east of Charlotte also might be sucking life out of the streams, experts say.As the price of gold mounts, some weekend prospectors have turned to machines called suction dredges. The devices work like underwater vacuum cleaners, sucking gravel and dirt into sluice boxes that catch any gold and dump other material back into the river.