Structure of Stream Food Webs

Researchers sample fish and salamanders in Lookout Creek at the HJ Andrews Experimental Forest

A food chain shows what eats what in an environment. A food web shows the structure of the interconnections between multiple food chains. Food webs show the architecture of trophic relationships, revealing the biodiversity and species interactions in an ecosystem. Most research about food webs has focused on species interactions while the influences of surrounding environments often have been overlooked.  Understanding which factors change the structure of a food web offers us the ability to predict how a food web will change when influential factors in the environment are altered.

A group of scientists from Oregon State University used pre-existing data from the HJ Andrews Experimental Forest to look at how the structure of aquatic food webs varied across a range of geophysical conditions within a whole stream system.

The researchers found that the structure of food webs responds to geophysical features at both local (i.e., slope) and broader (i.e., basin size) spatial extents. River food webs are complex because they not only include multiple species of aquatic insects and fish, but also all of their interactions. The researchers found that downstream food webs, with higher levels of omnivory, are more robust compared to upstream food webs, indicating that these complex networks can be fragile depending on the conditions of the surrounding environment. The analyses extends ecologists’ understanding of the stability of food webs and are a vital step toward predicting how webs and communities may respond to both natural disturbances and current global environmental change.

Full paper:  Zatkos, Lauren; Arismendi, Ivan; Johnson, Sherri L.; Penaluna, Brooke E. 2021. Geophysical templates modulate the structure of stream food webs dominated by omnivory. Ecosphere. 12(3): e03444. doi:https://doi.org/10.1002/ecs2.3444