Nutrient-sestonic chlorophyl relationships in northern Ozark streams

We investigated relationships between sestonic chlorophyll (Chl), total pho sphorus (TP), and total nitrogen (TN) at 23 sites an 13 streams in the Miss ouri Ozarks. There was a strong curvilinear relationship between mean sesto nic Chi and both mean TP (R-2 = 0.78) and mean TN (R-2 = 0.70). Both models were improved when catchment area was included with either TP (R-2 = 0.90) or TN (R-2 = 0.84). Limited to 17 sites without point source nutrient addi tions, the relationship between sestonic Chi and both TP and TN was linear Including catchment area strengthened linear models with either TP (R-2 = 0 .94) or TN (R-2 = 0.84). Land use (percent row crop or percent forest), tog ether with catchment size, was also a good predictor of sestonic Chl in Oza rk streams without point sources. When catchment area and TP or TN were use d to predict sestonic Chi on specific dates following catastrophic flooding , models were less accurate than those based on long-term averages, but sti ll explained 55-74% of the variance in sestonic Chi. Our results demonstrat e that sestonic Chi is closely associated with nutrients and catchment area in Ozark streams and that nutrient - sestonic Chl models may have broad ap plication in running waters.