Where are the parasites in food webs?

Abstract

This review explores some of the reasons why food webs seem to contain relatively few parasite species when compared to the full diversity of free living species in the system. At present, there are few coherent food web theories to guide scientific studies on parasites, and this review posits that the methods, directions and questions in the field of food web ecology are not always congruent with parasitological inquiry. For example, topological analysis (the primary tool in food web studies) focuses on only one of six important steps in trematode life cycles, each of which requires a stable community dynamic to evolve. In addition, these transmission strategies may also utilize pathways within the food web that are not considered in traditional food web investigations. It is asserted that more effort must be focused on parasite-centric models, and a central theme is that many different approaches will be required. One promising approach is the old energetic perspective, which considers energy as the critical resource for all organisms, and the currency of all food web interactions. From the parasitological point of view, energy can be used to characterize the roles of parasites at all levels in the food web, from individuals to populations to community. The literature on parasite energetics in food webs is very sparse, but the evidence suggests that parasite species richness is low in food webs because parasites are limited by the quantity of energy available to their unique lifestyles.

Unrevealing Parasitic Trophic Interactions—A Molecular Approach for Fluid-Feeding Fishes

“…The role of parasites in food webs has been largely disregarded (Sukhdeo, 2012). As an example, Winemiller and Polis (1996) was the most important contribution of food web studies but not approached the parasite-host interaction as part of the trophic webs.…”

“…Since Elton insights (Elton et al, 1931) it is known that parasites are very important links in the food webs and are capable of externing major effects on ecological interactions. Today, there is no longer the need to argue that parasites must be included in all models of ecosystem function (Sukhdeo, 2012). However, many questions remain as how parasites might fit in food webs, if it should be included or excluded in the food webs, what is the role of parasites in host population regulation, and what are the evolutionary and ecological implications of parasite mediation in trophic interactions (Sukhdeo and Hernandez, 2005).…”

Parasites of the Carolina Bay Lake-EndemicFundulus waccamensis(Waccamaw Killifish)

“…Some estimates suggest that parasites may outnumber freeliving species (reviewed in Dobson et al 2008) and that they are an understudied and underappreciated component of global biodiversity (Brooks and Hoberg 2000). The roles of parasites in aquatic ecosystems through impacting food webs , Lafferty et al 2006, Sukhdeo 2012, modifying host behavior (Barber et al 2000), and providing of ecosystem services , Lafferty 2008) are important factors in aquatic community ecology. Until this study, there had been no published research or surveys on the parasites of any endemic fish of Lake Waccamaw.…”

Description, microhabitat selection and infection patterns of sealworm larvae (Pseudoterranova decipiens species complex, nematoda: ascaridoidea) in fishes from Patagonia, Argentina

“…The sealworm larvae are much more disperse within the marine food webs and they propagate through complex feeding interactions ([4] and references therein). As far as it is known, the life cycle of species of Pseudoterranova also includes crustaceans as the first hosts, and fish as second hosts.…”