Food webs, defined as "who eats whom" in nature, have become a central topic within community ecology and thus they have been used to understand general ecological patterns such as biodiversity and species interactions as well as material and nutrient flows within ecosystems. In South America the knowledge of the taxonomy and distribution of freshwater invertebrates is incomplete and fragmented. Previous studies have focused on specific taxonomic groups and some countries such as Brazil and Argentina. In contrast, there have been many aquatic food webs published for UK freshwater systems with high levels of taxonomic resolution. This thesis aims to examine food web patterns in two geographically separated systems. The effects of systematic taxonomic aggregation on food web properties were examined and the relationship between consumer and prey body size revisited. A total of 24 food webs were examined in Chilean and Welsh streams, where 6128 invertebrate guts were examined to establish feeding interactions. These Chilean and Welsh food webs are amongst the largest, most complete and fully resolved. In both systems there was a high proportion of basal species, combined with low proportions of top and intermediate species. Significant differences were detected in most food web properties, in comparison to previous studies, where basal species were aggregated to coarser categories. No significant relationship between the body size of the consumers and their prey was found in either Chilean or Welsh streams. These results differ substantially from published data, and we attribute these differences to the greater taxonomic resolution particularly on the basal resources.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582554 |
| Date | January 2007 |
| Creators | Figueroa, David |
| Publisher | Queen Mary, University of London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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