Akana Noto

Ph.D. Candidate, University of California-San Diego

Field Travel Grant Type 1

The effect of sea-level rise on salt marsh community structure and stability

“Humans depend on ecological communities for invaluable ecosystem services that can be lost due to environmental degradation. Their loss often occurs unpredictably when environmental drivers exceed certain thresholds, but stable communities are less likely to undergo dramatic shifts after disturbances. Understanding the determinants of ecosystem stability is essential to maintaining functional ecosystems and the resources they provide. Stability is affected by factors such as environmental conditions and species interactions. Communities can become unstable if mean abiotic conditions change.

The effect of environmental variability on stability depends on whether species respond synchronously or asynchronously to fluctuations. Communities may be stabilized in fluctuating environments when species’ densities negatively covary due to compensatory dynamics. By contrast, if most species respond similarly to environmental conditions, then environmental variability and changes in mean abiotic conditions will likely reduce stability. Environmental changes that influence species interactions may indirectly alter community stability, possibly by changing synchrony. Dominant species often have strong stabilizing effects on communities, and their removal or loss due to changed environmental conditions can reduce community stability even if total plant abundance is unchanged. Thus, if environmental changes affect species abundances, stability may be indirectly affected by the resulting changes in species interactions.

In surveys I conducted last summer, I found that salt marsh plant communities vary in composition across short tidal gradients and therefore may be affected by small changes in environmental conditions. I propose to conduct an experiment to determine the effect of environmental change on salt marsh species interactions and community stability. Specifically, I will ask: How will SLR affect the dominant plant species and community stability? Understanding salt marsh stability is critically important since they provide ecosystem services such as storm protection, nutrient absorption and nursery habitat. In California, 90% of marshes have been destroyed, and those that remain face threats such as sea-level rise (SLR).”