Final answer:
Shannon-Wiener food web diversity is not commonly used as a descriptor for food webs, unlike connectance, chain length, and linkage density, which are used to characterize aspects of food webs.
Step-by-step explanation:
The descriptor that is not commonly used to describe a food web is d) Shannon-Wiener food web diversity. The other options, a) connectance, b) chain length, and c) linkage density, are all terms used to characterize aspects of food webs. Connectance refers to the proportion of possible links in a food web that are realized, chain length is the number of links between the trophic levels from the primary producers to the top predators, and linkage density describes the average number of links per species. On the other hand, the Shannon-Wiener index is a biodiversity index often used in the context of species diversity within a community but not specifically for food webs.