Parasite community structure as a predictor of host population structure: An example using Callorhinchus capensis

This paper describes the parasite community structure of the Cape elephant fish or St Joseph shark (Callorhinchus capensis) caught off the West and South Coast of South Africa between 2010 and 2015. These data were used to build species accumulation curves (SAC) and calculate biodiversity indices including rarefied species richness, Shannon Weiner's diversity index, Simpson's index and Pielou's J index. The biodiversity indices were correlated with the host's biological data to determine how these affected the parasite community structure and provide insight into the host's population structure. The parasites identified in C. capensis (n = 259) include a cestode (Gyrocotyle plana), two monogeneans (Callorhynchicotyle callorhynchi and Callorhinchicola multitesticulatus), an isopod (Anilocra capensis) and a leech (Branchellion sp.). Gyrocotyle plana was the most prevalent at 71.43% and the monogenean C. callorhynchi had the highest mean abundance (1.55 ± 0.45 parasites.fish^-1) and the highest mean infection intensity (4.79 ± 0.66 parasites.infected fish^-1). The SAC and biodiversity measures indicate a uniform parasite community across the sampled host population, suggesting a highly interactive shark community with no evidence for population structure. These results show that parasite community structure can be used to infer their host's population structure.