This investigation was concerned with determining the total amounts, forms, reactions, lability, and significance of the organic phosphorus pool in the sediments of two, small oligotrophic lakes. The two lakes selected for study (Bear and Lower Sylvan Ponds) differ markedly in productivity, but have similar morphometric features (shallow mean depth and low ratio of water volume/sediment area) which permit the sediments to play dominant, but contrasting, roles in the metabolism of the lakes. The results of this study indicate that in the unproductive lake (Lower Sylvan) the sediments act mainly as a sink for phosphorus, whereas in the productive lake (Bear) the sediments serve as a reservoir of available phosphorus. Investigation of the mechanisms responsible for this contrasting sediment influence was the primary objective and subject of this report. (Author)