Content area
Full text
About the Authors:
James H. Larson
* E-mail: [email protected]
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
William B. Richardson
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Brent C. Knights
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Lynn A. Bartsch
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Michelle R. Bartsch
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
John C. Nelson
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Jason A. Veldboom
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Jon M. Vallazza
Affiliation: Upper Midwest Environmental Sciences Center, United States Geological Survey, La Crosse, Wisconsin, United States of America
Introduction
Food quality has been shown to strongly influence the behavior, physiology, ecological interactions and evolution of aquatic consumers [1]–[3]. Some aspects of food quality appear to vary greatly among aquatic systems. For example, elemental composition of seston varies among streams in association with variation in watershed land use [4], and such variation influences consumer-driven processes [5], [6]. Less is known about the spatial controls over variation in many other aspects of food quality.
One aspect of food quality thought to be particularly important is lipid (and fatty acid) quantity and quality [7], [8]. FAs function as structural elements (primarily in cell membranes), energy storage molecules and precursors to signaling hormones [7], [9], [10]. Biota vary greatly in their ability to synthesize FA de novo. In particular, the enzymes necessary to synthesize long-chained (>20 C atoms), polyunsaturated FAs (PUFAs) are largely restricted to algae [11]. For metazoans, metabolically essential FA (e.g., eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) or their precursors (e.g., α-linolenic acid [ALA]) must be derived from the diet [7], [9], [12]. As a result, the quantity and composition of FA in food resources constitute an important aspect of food quality for aquatic consumers. Limitations in dietary FAs have been shown to limit cladoceran population growth, fish...