TERRESTRIAL LINKAGES TO EARLY SUCCESSIONAL PONDS FOLLOWING THE 1980 MOUNT ST. HELENS ERUPTION

Ponds created by the 1980 Mount St. Helens eruption are still in their early successional stages. As climate change warms the region, an increase in terrestrial organic carbon, i.e. brownification, is expected to alter pond habitats. Zooplankton communities in these ponds may experience profound habitat and resource changes due to terrestrial forest communities shifting from deciduous to coniferous vegetation. Eighteen mesocosms were established in 300-L cattle tanks near three perennial ponds in the Mount St. Helens National Volcanic Monument, Washington, USA. Using a factorial design, mesocosms were treated with deciduous or coniferous leaf litter crossed with a browning agent (i.e., humic acid). Ponds and mesocosms were sampled weekly for five weeks to examine zooplankton communities (abundance, biomass, richness), as well as trends in temperature, dissolved oxygen, pH, and nutrients. After three weeks, dissolved organic carbon (DOC) concentrations in mesocosms averaged four times higher in browning-deciduous treatments compared to deciduous treatments alone and eight-fold higher than the untreated controls, with DOC concentrations in coniferous mesocosms slightly lower than deciduous. There were differences in zooplankton community composition and biomass between the mesocosm treatments, with the largest abundance and diversity shifts from the control in browning-deciduous treatments. This study aims to understand the terrestrial-aquatic linkages in an early successional landscape and provide insight into zooplankton community structure and function.

Primary Presenter: Katey Queen, Western Washington University (queenk3@wwu.edu)

Authors:

Katey Queen, Western Washington University - Institute for Watershed Studies  (queenk3@wwu.edu)

Angela Strecker, Western Washington University - Institute for Watershed Studies  (strecka2@wwu.edu)