Conversion of acetylene reduction rates to nitrogen fixation rates in natural populations of blue-green algae

Twelve experiments are reported on naturally occurring groups of N₂-fixing blue-green algae in which reduction of acetylene and ¹⁵N₂ were determined simultaneously. Simple averaging of the $\text{C}{}_2\text{H}{}_2\text{N}{}_2$ reduction rates yielded a conversion factor of 4.4. Linear and log transform regression analyses yielded values of 4.8 and 4.2, respectively. Reports estimating nitrogen inputs based on acetylene reduction determinations are evaluated.