MACROPHYTE STANDING CROP AND PRIMARY PRODUCTWITY IN SOME FLORIDA SPRING‐RUNS¹

ABSTRACT: A survey of 31 Florida spring‐runs was conducted to estimate their submerged macrophyte standing crop and primary productivity. The standing crops of submerged vegetation were not significantly (p > 0.05) correlated to either total nitrogen (r = 0) or total phosphorus (r =−0.20) concentrations, but standing crops were significantly (p < 0.01) correlated to the percentage of the spring‐run's water surface shaded by marginal vegetation (r =−0.76). Maximum daily rates of primary productivity were positively correlated with average submerged macrophyte standing crops (r = 0.81; p < 0.001) and inversely correlated with the degree of shading by marginal vegetation (r =− 0.43; p < 0.05).