Thermal growth curves of Fe-limited and Fe-replete cultures of the marine nitrogen fixing cyanobacterium Trichodesmium. The thermal optimum of Fe-limited cells is shifted 5oC higher than for Fe-replete cells, so at 32oC warming largely alleviates Fe limitation (83%). Future Fe-limited Trichodesmium populations in a warmer ocean may thus be able to fix more nitrogen with the same amount of available Fe.