LAUSR

Environmental productivity and biodiversity are two intricately linked ecological concepts. One commonly observed pattern is a unimodal curve with biodiversity peaking at intermediate levels of productivity. While unimodal relationships are by no means universal, biodiversity declines at high productivity levels (eutrophication) raise serious concerns given anthropogenic nutrient inputs into waterbodies. One habitat that may be particularly vulnerable to eutrophication are California vernal pools. These ephemeral wetlands provide habitat to numerous threatened or endangered invertebrate taxa. To investigate the impact of eutrophication on invertebrates, experimental mesocosms were setup in the California State University, Sacramento Arboretum. Thirty mesocosms were inoculated with vernal pool soil and divided into five nutrient treatments in each of six blocks. Data was collected over a 21-week hydroperiod to quantify changes over a vernal pool hydroperiod. Nutrient addition increased mesocosm turbidity, chlorophyll-a, and phosphorus levels, in addition to causing larger shifts in dissolved oxygen and pH. While nutrient enrichment increased abundances of small crustaceans, there were no effects on taxa richness, or abundances of large branchiopods or insects. While these findings improve our understanding of bottom-up effects in vernal pools, questions remain over long-term nutrient inputs and interactions with other human activities.