PARENT SESSION
Poster Session 3: Aquatic Ecology
Monday, August 8, 5:00 PM - 6:30 PM, Exhibit Hall 210 D, Level 2, Palais des congrès de Montréal
Effects of the 17-year periodical cicada emergence on zooplankton communities in woodland ponds.
Valente, Jonathon*,1, González, María1, Nowlin, Weston1, Vanni, Michael1, Fields, Matthew1, Stevens, M. Henry1, 1 Miami University, Oxford, OH, U.S.A.
ABSTRACT- Allochthonous inputs are important resources pulses to aquatic ecosystems. In small woodland ponds these resources enter the system in the autumn in the form of fallen leaf material. Periodical cicada emergence can represent an additional resource subsidy during the spring/early summer and may alter food webs dynamics. We evaluated the effect of a resource pulse from a 17-year cicada emergence on food web dynamics of small woodland ponds. We conducted a 7-week experiment in 900 L mesocosms with four levels of cicada addition (0, 75, 150, and 300 cicadas/m2) with four replicates per treatment. Here, we present the responses of zooplankton communities. We hypothesized that 1) total zooplankton biomass would increase with increasing cicada additions and 2) zooplankton communities will be dominated by crustaceans due to the absence of fish. Addition of cicadas significantly increased total zooplankton biomass, with biomass increasing and peaking two weeks after the addition of cicadas, and falling to near initial levels by the end of the experiment. We also observed a temporal change in community composition in all treatments. Rotifer biomass was greater than crustacean biomass before cicada additions. After cicada additions, rotifer biomass decreased in all treatments. However, the decline occurred more rapidly in the control than in the cicada addition treatments. Crustacean biomass significantly increased immediately following the addition of cicadas and peaked two weeks after the addition of cicadas in all treatments. The highest crustacean biomass occurred in the intermediate addition treatment (15X initial levels) and the lowest in the control (2X initial levels). After this peak, crustacean biomass declined in all treatments. The decline in crustacean biomass occurred more rapidly in the control than in the nutrient addition treatments. After 7 weeks, crustacean biomass was similar to initial levels in the control, while in the high addition treatment crustacean biomass was still 5X greater than initial levels. These results indicate that large pulses of highly labile allochthonous material can have dramatic effects on zooplankton population dynamics.
Key words: zooplankton, periodical cicadas, allochthonous subsidies, temporary ponds