Do increasing nutrient concentrations affect biological condition?
Biological condition for macroinvertebrate, fish, and algal communities decreased with increasing concentrations of nitrogen and phosphorus in streams water. Changes in biological condition corresponding to increasing nutrient concentrations were more pronounced for algal communities than for macroinvertebrate or fish communities. This finding is consistent with the direct link between nutrient availability and algal growth, whereas the response of fish and macroinvertebrates to nutrients is indirect. That is, algae remove nutrients directly from stream water; whereas, macroinvertebrates and fish receive nutrients indirectly by consuming primary producers (aquatic plants or algae) or animals (macroinvertebrates or fish) for energy via food chains of various complexities.
