Understanding the stoichiometric limitation of herbivore growth: the importance of feeding and assimilation flexibilities |
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Authors: | Jotaro Urabe Yuichiro Shimizu Toshiyasu Yamaguchi |
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Institution: | 1. Graduate school of Life Sciences, Tohoku University, Sendai, Japan;2. Graduate school of Agriculture, Tohoku University, Sendai, Japan |
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Abstract: | Ecological stoichiometry suggests that herbivore growth is limited by phosphorus when this element in the diet is < 8.6 μg P mg C?1 (C : P atomic ratio > 300). However, in nature, it is not necessarily related to the relative phosphorus content in diets. This may be the result of complex feeding and assimilation responses to diets. We examined these possibilities using herbivorous plankton fed mono‐specific and mixed algae varying in phosphorus content of 1.6 to 8.1 μg P mg C?1. The herbivores showed a 10‐fold growth rate difference among the diets. Growth rates related poorly with phosphorus content in the diets (r2 = 0.07), better with P ingestion rate (r2 = 0.41) and best with phosphorus assimilation rate (r2 = 0.69). Inclusion of assimilation rates for carbon and fatty acids increased 7% of the explained growth variance. These results indicate that the feeding and assimilation flexibilities play pivotal roles in acquiring a deficient element and in regulating growth rate. |
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Keywords: | Algal diversity assimilation enhancement carbon dioxide compensatory feeding
Daphnia
ecological stoichiometry growth rate herbivorous plankton nutritional complementarity phosphorus |
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