Shares in the heavily traded dry bulk shipping sector were a bit stronger Tuesday, apparently bolstered by a spike in shipping rates after two weeks of steady declines. Dry bulk, the raw-materials freighters of the global economy, often see their stocks respond, like an ultra-sensitive seismograph, to the minute movements of things like commodities prices -- anything, in fact, that might indicate an uptick in worldwide trade. The industry is especially dependent on Chinese steelmakers' use of Australian and Brazilian iron ore, which the bulkers haul across the oceans. According to the London-based Baltic Exchange, spot-market rates for the huge Capesize-class ships (the ones too big for the world's canals) popped nearly 6% Tuesday to $53,600 per day. That follows 13 straight days of declines. Helping the move upward: four Capesize vessels were booked Tuesday morning to haul ore from Brazil to steel foundries in China and Europe. Coupled with some strength in the price of Chinese rebar -- a major steel-using (and thus iron-ore-using) product -- those who deal in dry-bulk equities were apparently cheered by the news. Dry bulk stocks, of course, are still hugely beaten down, along with the economy itself. Shares of fan favorite DryShips ( DRYS), for instance, were trading late morning Tuesday at $5.46, up 20 cents, or about 4%, on rather middling volume of 10 million shares.