Vertebrate diets derived from trophically transmitted fish parasites in the Bothnian Bay

Abstract

Parasites that are transmitted through predator-prey interactions may be used as indicators of trophic relationships between organisms. Yet, they are rarely used as such in the construction of topological (predator-prey) food webs. We constructed food webs of vertebrate trophic interactions using observed diet alone, trophically transmitted parasites alone, and the combination of the two based on data from 31 species of fish from the Bothnian Bay, Finland. The fish food web contained 530 links derived from observed diet, 724 links inferred from parasitism, and 1,058 links calculated from a combination of both stomach contents and parasites. This sub-web constructed from stomach contents had a mean of 17.1 links per fish species, while that using parasites had 23.4 links per fish. Combining the two diet indicators yielded 34.1 links per fish species, illustrating the complementarity of the two methods. Mean number of prey species per fish species was 12.5 using observed diet items, 15.8 using parasites, and 24.5 using both measures together. Mean number of predators per fish species was 7.4 using observed diet, 11.7 using parasites and 15.0 using both. A positive correlation was found between the mean number of parasites and the number of prey taxa in the diet among the fishes. Omnivorous fish had the highest diversity of both parasite species and prey items, while benthophagous fish had among the lowest. Mean total abundance and mean total prevalence of parasites correlated positively with fish size, with piscivores being the largest with the highest abundance and prevalence, while planktivores and benthivores had the lowest. Trophically transmitted parasites may be used to help construct vertebrate sub-webs and derive information about food web processes. Parasites alone provided equivalent if not more information than observed diet. However, resolution is improved by using parasites and observed diet together.

Evolution of complex life cycles in trophically transmitted helminths. I. Host incorporation and trophic ascent

“…Valtonen et al, 2010). Brown et al (2001) proposed that complex cycles evolved Step 2: the flexible two-host cycle, where the parasite is optimized to host i, but can also survive and reproduce in host j.…”

Parasite communities of two three-spined stickleback populations in subarctic Norway—effects of a small spatial-scale host introduction

“…Variation in biotic factors, such as the foraging behavior of fish hosts in novel habitats, could possibly affect introduced parasite populations. Fish foraging behavior is linked to the host's acquisition of trophically transmitted parasites (Klimpel et al 2003;Knudsen et al 2004;Valtonen et al 2010;Locke et al 2014) and could therefore be a potential factor controlling the abundance of trophically transmitted parasites.…”

Infection dynamics of Caryophyllaeid tapeworm, Adenoscolex oreini Fotedar, 1958 and impacts of intra-lake pollution gradient on intermediate host (copepods) and health attributes of Schizothorax spp.

“…The role of feeding behaviour on the occurrence of parasitism in fish is well documented in the literature. The role of foraging behaviour, for example, has been reported as an important determinant of parasite communities (Knudsen et al 2004;Valtonen et al 2010). The feeding behaviour of different species of genus Schizothorax, which have been studies in past, revealed that these fishes are herbivores, and their diet is mainly composed of phytoplankton and rest contained aquatic invertebrates (Jan and Das, 1970).…”