You discover a new type of marine organism that has the kidneys of a fish but no gills. what effect would the absence of gills have on excretion of nitrogenous waste? no effect. nitrogenous wastes diffuse across the skin. no effect. fish kidneys excrete all nitrogenous waste. nitrogenous excretion increases at the kidneys because it cannot be lost at the gills. nitrogenous excretion decreases because no nitrogen uptake is occurring at the gills.