Effects of stream nutrient enrichment on aquatic insect stoichiometry : importance of life-history traits, sex, and ontogeny.

Back, Jeffrey Alan.
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I investigated the effects of stream nutrient enrichment on aquatic insect stoichiometry, particularly in the context of species life-history traits, sex, and ontogeny. The majority of studies investigating nutrient content of organisms preceding this research had assumed that aquatic insect species maintain a homeostatic concentration of carbon, (C) nitrogen (N) and phosphorus (P) content with respect to developmental stage and nutrient enrichment of their food resources. However, P content was shown not to be homeostatic across the ontogeny of 19 species of aquatic insects and C and N were quasihomeostatic. Growth rates for Caenis mayflies were higher on P enriched foods, and smaller individuals grew faster than larger individuals. Further, female mayflies were equal to or larger than males and had equal or higher body P content than males, depending upon species. A phylogenetic pattern in body P content was found for baetid and leptophlebiid mayflies. Male and female baetids declined in % P across their ontogeny, whereas leptophlebiid females increased in the 3 species studied. Finally, a study of streams spanning a steep nutrient enrichment gradient revealed that females of Baetis sp. and Neochoroterpes nanita attained a much larger size than males and were more enriched in P. Body P content of both mayfly species was higher at low P sites, and body size was much larger at high P sites. In insects, P content is a good indicator of growth rate (higher P, faster growth), and body size is a good predictor of fecundity (bigger body, more fecund). Nutrients not only play a role in determining an organism’s reproductive success, growth rate and size. The effects of nutrients are seen in organism nutrient recycling rates, food web organization, and community structure and function.

Ecological stoichiometry., Ontogeny., Phosphorus., Aquatic insects., Sex., Life-history traits., Nutrients.
Back, J. A., Taylor, J. M., King, R. S., Fallert, K. L., and Hintzen, E. H. "Ontogenic differences in mayfly stoichiometry influence growth rates in response to phosphorus enrichment." Fundamental and Applied Limnology 171, 3 (2008): 233–240.
Back, J. A. and King, R. S. "Sex and size matter : ontogenetic patterns of nutrient content of aquatic insects." Freshwater Science 32, 3 (2013): 837-848.