FOOD-WEB PATTERNS - LESSONS FROM A SPECIES-RICH WEB

(1) The properties of a large and well-documented estuarine food web are examined to see how closely they conform to the patterns described for food webs in general. Average food-chain lengths are longer and the degree of omnivory is higher than for the majority of published webs. The web is similar to others in the proportions of top, intermediate and basal species and the links between them, and in the relationships between the number of trophic links and web size and between the number of predators and the number of prey. (2) The effects of taxonomic resolution on web properties are examined by progressively aggregating web elements into coarser taxonomic classes. Aggregation resulted in a marked reduction in average food-chain length and reproduced the relationship between the number of trophic links and the number of species and between the number of predators and the number of prey. The proportions of top, intermediate and basal species and the proportions of links between these groupings were insensitive to our aggregation procedure.