Food Webs, Cascades, Trophic Positions, and Stoichiometry

One of the first conceptual models of energy flow through a food web was developed by Raymond Lindeman based on his studies of a single lake. Our understanding of how food web is structured, and our ability to quantity trophic position of consumers has advanced considerably. The structure of food webs is not only determined by what food and how much is available to consumers, but also dictates how nutrients are regenerated. When grazers consume food, they sequester the nutrients they need and excrete or release the rest. This has the potential to skew nutrient proportions for primary producers. Mixoplankton that combine autotrophy and heterotrophy in a single organism further complicate food web interactions directly and indirectly. The complexity of food webs, the approaches by which they can be teased apart, and how considerations of mixotrophy alter our perspectives of food web interactions are considered in this chapter.