Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster E64
Ólafur K. Nielsen2, Karl Skírnisson3 and Gunnar Stefánsson4
1. Líf- og umhverfisvísindadeild Háskóla Íslands, 2. Náttúrufraedistofnun Íslands, 3. Tilraunastöð Háskóla Íslands, 4. Raunvísindastofnun Háskóla Íslands
Kynnir / Presenter: Ute Stenkewitz
Tengiliður / Corresponding author: Ute Stenkewitz1,2,3 (ute@ni.is)
Details on the parasite community of Icelandic rock ptarmigan and their potential impact on population Dynamics: The population density of Icelandic rock ptarmigan fluctuates in multiannual cycles with peak numbers c. every 10 years. How the ptarmigan parasite community acts and how parasites relate to ptarmigan age, body condition, and population density has been investigated in this study. The study is part of a PhD and embedded in the Ptarmigan Health Project that has been running since 2006. From 2006 to 2012 in early October, we collected 632 ptarmigan in northeast Iceland. Out of those, 630 (99.7 %) birds were infected with at least one parasite species, 616 (98 %) with ectoparasites and 536 (85 %) with endoparasites. The main factors associated with variation in the parasite community were host age and time. Juvenile birds carried overall more parasites than adults and there were distinct fluctuations in the course of the years of this study. Ptarmigan population density was associated with the coccidian parasites E. muta and E. rjupa in juvenile birds. Annual aggregation levels of these eimerids fluctuated inversely with prevalence, with lows at prevalence peaks and vice versa, and both prevalence and aggregation tracked ptarmigan population density with a 1.5 year time lag. This time lag can partly be explained by the host specificity of the eimerids and their persistence in and transmission through the environment (in feces) from one year to the next. Further, ptarmigan body condition was negatively affected at high intensities of E. muta and E. rjupa marginally, an indication for their pathogenicity. Our findings indicate that E. muta and E. rjupa conveying a negative impact on body condition in juvenile birds could act to destabilize ptarmigan population dynamics in Iceland. How the population parameters ptarmigan survival and fecundity are affected by parasites is under investigation. A likely alternative is that sublethal parasitism may act synergistically with predation and other factors to destabilize the ptarmigan population.