relation of incident radiation to diurnal rates of photosynthesis in Lough Neagh

The homogeneous nature of the water column in L. Neagh enabled the testing of a semi‐empirical model for calculating the integral gross photosynthesis with respect to depth and time. In particular a logarithmic function describing the photosynthetically available radiation was examined, as the other major determinants in the model remained relatively constant, during a diurnal study on 3. 6. 70. Agreement between planimetric and calculated rates of integral gross photosynthesis for both instantaneous and daily periods is comparable with the performance of more complex models; however the problem of measuring net yields of ‘column’ photosynthesis remain.