Resource tracking in marine parasites: going with the flow?

Abstract

Understanding how diversity interacts with energy supply is of broad ecological interest. Most studies to date have investigated patterns within trophic levels, refl ecting a lack of food webs which include information on energy fl ow. We added parasites to a published marine energy-fl ow food web, to explore whether parasite diversity is correlated with energy fl ow to host taxa. Parasite diversity was high with 36 parasite taxa aff ecting 40 of the 51 animal taxa. Adding parasites increased the number of trophic links per species, trophic link strength, connectance, and food chain lengths. Th ere was evidence of an asymptotic relationship between energy fl owing through a food chain and parasite diversity, although there were clear outliers. High parasite diversity was associated with host taxa which were highly connected within the food web. Th is suggests that energy fl ow through a taxon may favour parasite diversity, up to a maximal value. Th e evolutionary and energetic basis for that limitation is of key interest in understanding the basis for parasite diversity in natural food webs and thus their role in food web dynamics.

Host taxonomy constrains the properties of trophic transmission routes for parasites in lake food webs

“…Abundant prey may also represent a more productive niche that can be exploited by more parasite species (Thompson et al. ). Of course, infecting highly abundant prey means that the parasite will often be consumed by predators that are not viable definitive hosts and die.…”

“…Instead, parasites might “go with the flow” and tend to be transmitted along links that transfer a large amount of biomass (Thompson et al. ). These energetic “highways” might involve abundant prey, but they could equally involve rare but large prey.…”

“…Whatever the case may be, links that transfer large amounts of biomass represent major flows of energy and nutrients through a community and may therefore occur more reliably than other links (Thompson et al. ).…”

“…, Thompson et al. ), and highly central hosts tend to be particularly important for parasite transmission (Chen et al. ).…”

“…, Rossiter and Sukhdeo , Thompson et al. ), meaning it is possible that parasites tend to infect highly connected species largely because of the taxonomy of these highly connected species rather than because these hosts best allow parasites to complete their life cycles. When testing for effects of the properties of feeding links on the potential for these links to transmit parasites, it is therefore essential to control for the potential influence of the taxonomy of free‐living species.…”