The contrasting hidden consequences of parasitism: effects of a hematophagous nematode (Uncinaria sp.) in the development of a marine mammal swimming behavior.

1. Parasites are an important part of ecosystems, playing a critical role in their equilibrium. However, the consequences of parasitism beyond the direct effects associated with disease and mortality are not completely understood. This gap in knowledge is in part due to the difficulties to isolate the effect of single parasite species on physiological and behavioral traits in natural systems. 2. The South American fur seal (Arctocephalus australis)-hookworm (Uncinaria sp.) interaction offers an ideal system to overcome these difficulties and study the behavioral and physiological effects of parasites in their hosts. 3. Hookworms cause stunted growth and anemia in pinniped pups, which could affect early life active behaviors such as swimming. The aim of this study was to determine the effects of hookworms (Uncinaria sp.). on the development of swimming capabilities in A. australis through physiological and ethological analyses. 4. Higher parasite burden was associated with reduced gr...