PARENT SESSION
Contributed Oral Session 91: Aquatic Ecology: Wetland Management; Stream Chemistry
Wednesday, August 10, 1:30 PM - 5:00 PM, Meeting Room 513 A, Level 5, Palais des congrès de Montréal

Terrestrial-aquatic linkage: The effects of periodical cicadas on stream ecosystem function.

Menninger, Holly^*,1, Palmer, Margaret¹, Craig, Laura¹, Hassett, Brooke¹, Richardson, David¹, Smith, Robert¹, ¹ University of Maryland, College Park, MD

ABSTRACT- The emergence of Brood X periodical cicadas (Magicicada spp.) in summer 2004 provided a unique opportunity to study the effects of a terrestrially-derived resource pulse on adjacent aquatic ecosystems. We predicted that the large input of nutrient-rich cicada carcasses would stimulate whole-stream community respiration. We measured periodical cicada emergence density in two suburban Maryland riparian forests (NW13, NW8) and the subsequent input of carcasses into adjacent streams through their entire flight season (12 May − 28 June 2004). We measured whole-stream rates of community respiration four times at each site, once prior and three times during the cicada flight season. We estimated standing stock of cicada detritus (g dry mass m^-2) available to stream biota on the days we measured community respiration. Cicada emergence density in our suburban riparian forests was lower than previously reported in floodplains, with average densities of 29.64 cicadas m^-2 and 9.34 cicadas m^-2 at NW13 and NW8, respectively. Peak input of cicada carcasses occurred during the first week of June at both sites. Community respiration increased by 85% on June 7 compared to pre-cicada respiration measurements at NW13 (April 28: 12.82 g O₂ m^-2, June 7: 23.78 g O₂ m^-2) and increased by 376% on June 22 at NW8 (April 29: 2.76 g O₂ m^-2, June 22: 13.14 g O₂ m^-2). Correlation analysis between community respiration rates and estimated standing stock of cicada carcasses in-stream suggests a positive relationship at NW13 (Pearson′s r = 0.94, p = 0.061), yet no statistical relationship at NW8, likely a function of low sample size. We conclude that the emergence of the Brood X periodical cicadas in eastern U.S. suburban riparian forests during summer 2004 resulted in a large pulse of nutrient-rich detritus to streams that, in turn, affected stream ecosystem function.

Key words: terrestrial-aquatic linkage, ecosystem function, stream, cicada