A predicted change in the amino acid landscapes available to freshwater carnivores

Anthropogenic effects lead to nonrandom alterations to macroinvertebrate communities, which may lead to alteration of the ‘micronutrient landscapes’ experienced by higher consumers. Understanding how amino acid composition varies among taxa and guilds is an essential step toward predicting how micronutrient landscape alteration will affect carnivores. We assessed whether: 1) wild macroinvertebrate prey varied in their amino acid compositions, 2) variation in amino acid composition was correlated with economical selection pressures or functional traits that may separate the compositions of functional feeding groups (FFGs) or is simply a result of phylogeny, and 3) simulated anthropogenic change in the composition of macroinvertebrate communities affects the amino acid composition of the nutrient landscape. Amino acid composition varied significantly among taxa and was strongly correlated with phylogeny but not FFGs. The amino acid compositions of holometabolous insects (those that undergo complete metamorphosis; Trichoptera and Diptera) differed from those of hemimetabolous insects (those that undergo incomplete metamorphosis; Ephemeroptera and Hemiptera). This separation can be explained by morphological and physiological traits involved in pupation or nymphal development. Simulated deterioration of macroinvertebrate communities changed the amino acid landscape, resulting in lower availability of threonine, phenylalanine, proline, and tyrosine to carnivores. Amino acid availability to carnivores is likely to respond more to the loss of taxonomic lineages than to loss of prey FFGs. Our study provides a critical first step toward understanding how changes to macroinvertebrate communities might affect the availability of amino acids to higher consumers.