Professor, Department of Biology Eastern Washington University Cheney, Washington, United States
Abstract: Vernal pools are ephemeral wetlands that fill annually from winter and spring precipitation but remain dry for much of the year. Though important habitats and sources of freshwater biodiversity, they are little accounted for in wetland conservation and restoration practices. Like much of the world’s wetlands, they have seen significant decline from anthropogenic impacts and conversion for alternative land use. Pools are also at significant risk due to the impacts of climate change and invasives. These small temporary waterbodies perform vital ecosystem services and host rare and endemic species. Anostraca, or fairy shrimp, lay resting eggs that form dormant desiccation-tolerant banks in the substrate of dry pools and hatch with rehydration. Vernal pools in Eastern Washington lack information on their conditions and inhabitants. This study examines the current water quality conditions and fairy shrimp species of 25 pools along the Columbia Basin Plateau. We are 1) monitoring pools throughout their complete hydroperiods, 2) determining egg bank species diversity by hatching and rearing under experimental lab conditions, and 3) examining the effects of environmental conditions on hatching, and 4) comparing pool conditions and fairy shrimp occurrence over short (1-year) and long (24-year) timescales. This study will establish how the pools fare currently and make recommendations for mitigating any further degradation. The study is ongoing, but early results suggest little species overlap within pools. Even in close proximity, pools may have strongly divergent species representation and water quality conditions. Hatching timing appears to be most related to pool thaw date, ultimately impacting the timing of shrimp maturation. While the species found and confirmed to date, Branchinecta cornigera and Eubranchipus hesperius can co-exist together within pools, we found comparatively high pH and DO values in B. cornigera-containing pools (avg. ~9.5, ~113%) relative to E. hesperius-containing pools (avg. ~7.3, ~46.8%). Pools with shrimps do not represent the same species known to this area 20 years ago and many former pools no longer fill. As the field season wraps up, future lab studies will examine egg bank species representation and hatching/survival success based on the effects of DO, nitrates, and temperature.
