Winter Freeze Decreases the Emergence of Fauna and Flora in California Vernal Pools

Impacts of global climate change is observed in many ecological systems. Temporary aquatic ecosystems, including California vernal pools, are especially sensitive to climatic variation, but most species are adapted to the annual fluctuations in precipitation and temperature. Since vernal pools experience an inundation and desiccation every year, species that occupy the ecosystem have adaptations to this cycle. Many species survive drought by creating resting eggs to then re-emerge upon inundation However, climate changes outside the typical range may have deleterious effects on these populations. Moreover, climate variation can have secondary effects on the community. For example, the amount of precipitation will influence community size, which may affect the community. While these effects have been documented in some other aquatic ecosystems, the interactions among temperature and community size has not been addressed in temporary aquatic ecosystems, including California vernal pools. A microcosm experiment was conducted that manipulated volume and temperature (freezing) and measured the response in water quality (phosphorus, dissolved oxygen, conductivity, and turbidity) and organisms (invertebrates, plants, and algae). Twenty vernal pool microcosms were established with inundated vernal pool soil collected near Sacramento, California. The experiment was a 2 x 2 factorial design with 2 levels of volume (3L and 2.25L) and 2 levels of temperature (initially frozen or not). Treatments were implemented at inundation with biweekly sampling. Pools that were frozen at inundation housed a significantly smaller population of both invertebrates and plant life than those that were not initially frozen. Volume had no significant effects on species richness or abundance. Due to the sensitive nature of the cysts and seeds during their dormant stage, understanding the environmental complexities of ephemeral wetlands is a challenging but important tool in implementing adaptive management into restoration