Can parasites be indicators of free-living diversity? Relationships between the species richness and abundance of larval trematodes with that of local fishes and benthos
Measuring biodiversity is difficult. This has spawned efforts to seek taxa whose species richness correlates with the species richness of other taxa. Such indicator taxa could then reduce the time and cost of assessing the biodiversity of the more extensive community. However, the search for species richness correlations has yielded mixed results. This may primarily be due to the lack of functional relationships between the taxa studied. Trematode parasites are highly promising bioindicators. Diverse assemblages of larval trematode parasites are easily sampled in intermediate host snails. Through their life cycles, these parasites are functionally coupled to the surrounding free-living diversity of vertebrate and invertebrate animals. Larval trematodes in snails have been demonstrated to positively correlate with bird diversity and abundance. Here, we explore whether trematodes also correlate with standard measures of fishes, large and small benthos, across 32 sites in three wetlands. We found associations between trematodes and benthic communities that were not consistent across wetlands. However, the associations were consistently positive for large benthic species richness and density. Additionally, some of the contrasting associations between trematodes and benthos may be explained by negative associations between large and small benthos. We found no associations with fish communities (likely due to the inadequacy of standard ‘snapshot’ sampling methodologies for highly mobile fishes). The results support further exploration of trematodes as bioindicators of diversity and abundance of animal communities.