Caloric and Micronutrient Content of Nuphar polysepalum

Abstract

Caloric equivalents are cited for eight vegetative and reproductive tissue types of Nuphar polysepalum; leaf blade tissue was highest (4499 cal/g ash-free dry weight) and rhizome tissue lowest (3976 cal/g ash-free dry weight). In addition, the concentration of Fe, Mn, Cu, and Zn was determined for each tissue type; leaf blade tissue was consistently highest for each micronutrient while seed tissue was consistently lowest. N. polysepalum is nearly always restricted to Colorado semidrainage mountain lakes; lakes whose waters have consistently high levels of total Fe, N03-N, and humic acid (color). Energy and micronutrient content of aquatic macrophytes is becoming increasingly important economically and ecologically. Westlake (1965) emphasized the need for data concerning the caloric and chemical composition of aquatic vascular plants, particularly as they relate to our study and understanding of energy flow in aquatic ecosystems. Caloric values for about 35 species of aquatic angiosperms have been cataloged (Cummins and Wuycheck 1971). In nearly all cases either the entire plant was used or conspicuous (above ground) vegetative and reproductive parts were combined before analysis. The primary objective of this paper is to present caloric equivalents for eight vegetative and reproductive parts of the yellow pond-lily Nuphar polysepalum Engelm. 1865 (-Nuphar luteum subsp. polysepalum). A second objective is the presentation of micronurient (Cu, Fe, Mn, and Zn) content within these eight tissue types. A final and tertiary objective is to document a unique set of limnological conditions of a Colorado semidrainage mountain lake (Red Rock Lake) for which Nuphar polysepalum is an indicator species of lake type in Colorado and is the predominant hydrophyte and photoautotroph. METHODS AND MATERIALS. Selected structural parts of Nuphar polysepalum, a perennial herb common to the unique semidrainage lakes of western North America (Pennak 1969), were collected from Red Rock Lake, Colorado, (Fig. 1) during the period June-September 1968 and 1969. Red Rock Lake is a 1Contribution No. 1 from the Water Resources Research Laboratory, The University of Southern Colorado.