Anthropogenic Disturbance: A Possible Regulator of Sin Nombre Hantavirus?
Lehmer, Erin*,1, Dearing, Denise1, St. Jeor, Stephen2, 1 University of Utah, Salt Lake City, UT2 University of Nevada School of Medicine, Reno, NV
ABSTRACT- Deermice (Peromyscus maniculatus) are the primary reservoir and vector for Sin Nombre (SN) hantavirus, a virus that causes disease with high mortality in humans. Several recent studies have proposed that anthropogenic habitat disturbance has significant affects on prevalence of SN in deermice; however, these hypotheses are in opposition to each other with respect to their predicted outcomes. Our objectives were to 1) measure SN infection in deermice across a gradient of disturbance and 2) evaluate the influence of disturbance on SN prevalence and deermouse densities. We focused on the percentage of bare ground created by off-road vehicles as a primary indicator of habitat disturbance. From 2003-2004, we sampled 1297 deermice captured from 17 sites distributed across a gradient of disturbance in the Great Basin desert. Across sites, prevalence varied from 0.0% to 38.7% and prevalence was higher in 2004 than in 2003 (8% vs. 17%; t = 3.3, P < 0.01). The percentage of bare ground on our study sites and the year of sampling accounted for 64.2% of variation in SN prevalence (F = 2.53, P = 0.02) among deermice. Specifically, we detected a negative relationship between SN prevalence and the percentage of bare ground (coef. = -3.48; F = 12.55, P < 0.01) and a difference in prevalence across years (coef. = 0.61; F = 12.17, P < 0.01), with prevalence increasing from 2003 to 2004. When each year of the study was considered independently, we found an especially strong relationship between SN prevalence and bare ground in 2003 (coef. = -.693; F = 10.23, P < 0.01; r2 = 0.39). However, in 2004 bare ground was not related to SN prevalence, but deermouse density had a strong positive influence on SN prevalence (coef. = 0.09; F = 8.34, P = 0.01; r2 = 0.28). Deermouse densities on our study sites ranged from 0.65 to 27.74 deermice / ha and although densities did not differ between spring and fall in either 2003 (t = 0.04, P = 0.97) or 2004 (t = 0.52, P = 0.60), deermouse density was higher in 2003 than in 2004 (t = 1.55, P = 0.04). Collectively, these patterns suggest that habitat disturbance plays a large role in SN prevalence at high, but not low population densities. We are investigating how density and habitat disturbance influence age structure and rates of population turnover as possible mechanisms to explain these patterns of SN prevalence.
Key words: hantavirus, disturbance, Peromyscus, maniculatus
All materials copyright The Ecological Society of America (ESA), and may not be used without written permission.