Macroparasite Infections of Amphibians: What Can They Tell Us?

Abstract

Understanding linkages between environmental changes and disease emergence in human and wildlife populations represents one of the greatest challenges to ecologists and parasitologists. While there is considerable interest in drivers of amphibian microparasite infections and the resulting consequences, comparatively little research has addressed such questions for amphibian macroparasites. What work has been done in this area has largely focused on nematodes of the genus Rhabdias and on two genera of trematodes (Ribeiroia and Echinostoma). Here, we provide a synopsis of amphibian macroparasites, explore how macroparasites may affect amphibian hosts and populations, and evaluate the significance of these parasites in larger community and ecosystem contexts. In addition, we consider environmental influences on amphibian-macroparasite interactions by exploring contemporary ecological factors known or hypothesized to affect patterns of infection. While some macroparasites of amphibians have direct negative effects on individual hosts, no studies have explicitly examined whether such infections can affect amphibian populations. Moreover, due to their complex life cycles and varying degrees of host specificity, amphibian macroparasites have rich potential as bioindicators of environmental modifications, especially providing insights into changes in food webs. Because of their documented pathologies and value as bioindicators, we emphasize the need for broader investigation of this understudied group, noting that ecological drivers affecting these parasites may also influence disease patterns in other aquatic fauna.

Predator diversity, intraguild predation, and indirect effects drive parasite transmission

“…In this system, free-living, parasitic trematode cercariae are transmitted from snails, the first intermediate host, to tadpoles, the second intermediate host (22) (see SI Background for a description of the life cycle) and several vertebrate and invertebrate taxa are known to consume cercariae (e.g., refs. 9 and 23-25; see SI Background for more details).…”

Constraining the Deep Origin of Parasitic Flatworms and Host-Interactions with Fossil Evidence

“…Studies on pathology have focused on invertebrate intermediate hosts (Ruiz and Lindberg, 1989;Ituarte et al, 2001Ituarte et al, , 2005Huntley, 2007;Huntley and Scarponi, 2012;Huntley et al, 2014;Huntley and De Baets, 2015), although some pathologies in vertebrate intermediate hosts have also been linked with parasitic flatworms. The best examples are probably the teratological limb malformations in North American amphibians, which have been linked with the trematode Ribeiroia on several occasions (Johnson et al, 2001(Johnson et al, , 2002Stopper et al, 2002;Johnson and Sutherland, 2003;Johnson and Chase, 2004;Koprivnikar et al, 2012) and could potentially be found in the fossil record (cf . Fr€ obisch et al, 2014).…”

Quantifying larval trematode infections in hosts: A comparison of method validity and implications for infection success

“…Ongoing declines and deformities in amphibian populations have catalyzed increased interest in the effects of parasites and pathogens on amphibian ecology and conservation (Blaustein et al, 2012;Densmore and Green, 2007;Kilpatrick et al, 2010;Koprivnikar et al, 2012). Alongside habitat loss, climate shifts, and pollution, infectious diseases represent one of the most important threats confronting amphibians worldwide (Collins and Storfer, 2003;Lips et al, 2006;Stuart et al, 2004).…”