The Florida Everglades possesses extensive mat-forming microbial communities (periphyton) with a great influence on basic attributes of the ecosystem. In the Everglades, periphyton mats are a major component of the base of the food web and are responsible for as much as 50% of net primary productivity. Additionally, mats provide habitat structure and regulate the availability of nutrients and gases within the water column. Periphyton is highly sensitive to changes in nutrient availability and can dissociate as conditions change. The exact mechanism behind mat dissociation remains unknown, but it may be due to changes in co-dependencies between species. Resource limitation often determines the presence and strength of species co-dependencies. Several works by other authors have identified aspects of community dynamics that are analogous to the behavior demonstrated by complex mathematical networks and have demonstrated the ability to predict shifts in community structure in response to changes in one or more environmental variables, which has implications for environmental management and restoration projects. As diatom species data is already used to measure water quality, we are exploring the use of networks constructed from diatom abundance data to measure the health of periphyton in the Everglades.
Results/Conclusions
Network structure is lost with increasing TP in periphyton. This indicates that as mats are exposed to higher phosphorus loads, the community composition is less constrained, and species co-occurrence is less meaningful as the previously-known replacement of endemic oligotrophy-tolerant species with cosmopolitan species takes place. This provides a new insight into potential mechanisms behind the loss of periphyton cover.