Seasonal fluctuations of host densities and environmental factors are common in many ecosystems and have consequences for biotic interactions, such as the transmission of parasites and pathogens. Here, we investigated seasonal patterns in all host stages associated with the complex life cycle of the intertidal trematode Maritrema novaezealandensis on a mudflat where this parasite's prevalence is known to be high (Lower Portobello Bay, Otago Harbour, New Zealand). The first intermediate snail host Zeacumantus subcarinatus, a key second intermediate crustacean host, the amphipod Paracalliope novizealandiae, and definitive bird hosts were included in the study. The density (snails, amphipods), abundance (birds), prevalence, i.e. percentage of infected individuals, and infection intensity (snails, amphipods) of the studied organisms were assessed. Furthermore, temperature was recorded in tide pools, where transmission mainly occurs, over a 1 yr period. Overall, the trematode prevalence in snail hosts was 64.5%, with 88.4% of infected snails harbouring M. novaezealandensis. There was a strong seasonal signal in prevalence and infection intensity in second intermediate amphipod hosts, with peaks for both parameters in summer (over 90% infected; infection intensity: 1 to 202 parasites per amphipod). This peak coincided with the highest abundance of definitive bird hosts and of small and still uninfected snails present on the mudflat. Our observations indicate that all of the transmission events necessary to complete the complex life cycle of this parasite primarily occur during warmer months.
KEY WORDS: Seasonality · Parasite transmission · Host -parasite interactions · Temperature · Maritrema novaezealandensis · Paracalliope novizealandiae · Zeacumantus subcarinatus
Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 455: [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93] 2012 1995, Wilson et al. 2002). In intertidal ecosystems, the extent of environmental fluctuations is inherently pronounced. Trematode parasites are very common and highly influential components of these ecosystems and usually have complex life cycles involving several members of an intertidal community. Trematodes have been shown to play crucial roles in host population dynamics as well as community and food web structures (e.g. Lauckner 1984, Sousa 1991, Mouritsen & Poulin 2002b, Thompson et al. 2005, Wood et al. 2007, Mouritsen & Poulin 2010, and they constitute a considerable and highly underestimated amount of biomass in natural systems (Kuris et al. 2008).Infection levels of trematodes in intertidal host populations substantially differ not only spatially (e.g. Smith 2001, Kube et al. 2002a, Latham & Poulin 2003, Hechinger & Lafferty 2005, Byers et al. 2008) but also temporally (e.g. Hughes & Answer 1982, Lauck ner 1987, Meißner & Bick 1997, Al-Kandari et al. 2000, Kube et al. 2002b, Jen sen et al. 2004, Al-Kandari et al. 2007). Many aspects of the transmission of trematodes ar...