The Ecological Importance of Amphipod–Parasite Associations for Aquatic Ecosystems

Abstract

Amphipods are a key component of aquatic ecosystems due to their distribution, abundance and ecological role. They also serve as hosts for many micro- and macro-parasites. The importance of parasites and the necessity to include them in ecological studies has been increasingly recognized in the last two decades by ecologists and conservation biologists. Parasites are able to alter survival, growth, feeding, mobility, mating, fecundity and stressors’ response of their amphipod hosts. In addition to their modulating effects on host population size and dynamics, parasites affect community structure and food webs in different ways: by increasing the susceptibility of amphipods to predation, by quantitatively and qualitatively changing the host diet, and by modifying competitive interactions. Human-induced stressors such as climate change, pollution and species introduction that affect host–parasite equilibrium, may enhance or reduce the infection effects on hosts and ecosystems. The present review illustrates the importance of parasites for ecosystem processes using examples from aquatic environments and amphipods as a host group. As seen from the literature, amphipod–parasite systems are likely a key component of ecological processes, but more quantitative data from natural populations and field evidence are necessary to support the results obtained by experimental research.

Parasite ecology of Carassius gibelio (Bloch, 1782) in Jandari Lake (Georgia)

“…Similar results were shown for the population of prussian carp in Lake Sakadaš, Croatia (Vuić et al 2022). In the parasitic fauna of fish, the coexistence of different species is often noted among the various forms of parasitic relationships (Kennedy 2009;Dallas et al 2019;Giari et al 2020). A parasitological examination of gibel carp in Jandari Lake revealed the simultaneous invasion of two different taxonomic groups into the fish gills-protozoans and monogeneans.…”

Infection with acanthocephalans increases tolerance of Gammarus roeselii (Crustacea: Amphipoda) to pyrethroid insecticide deltamethrin

“…While reliable cause-and-effect studies are challenging, the combined effects of parasites in intermediate and final hosts and pollutants are increasingly studied as part of the recently established research direction ‘Environmental Parasitology’ (Giari et al 2020 ). Whether negative effects of parasite infections, e.g., the reduction of growth, respiration rate, or egg production of acanthocephalan species on intermediate hosts (Kennedy 2006 ) are moderated by the potential positive effects of reduced contaminant exposure requires further investigation.…”

New species, new story: The impact of invasive non‐host predators on host‐trematode interactions

“…Ecological experiments performed in the laboratory face limitations related to mimicking natural environmental conditions. Field evidence is therefore necessary to support the results obtained through an experimental approach (Giari et al, 2020). Here, for example, the small size of the testing arena can make cercarial prey more accessible to a predator, and these digenean larvae can locate their target host ("shelter") more quickly.…”

“…The aim was to compare the ability of two native European (Gammarus jazdzewskii Rudolph et al, 2018 andG. pulex [Linnaeus, 1758]) and two invasive Ponto-Caspian (Dikerogammarus villosus [Sowinsky, 1894] and Pontogammarus robustoides [Sars, 1894]) predator gammarid species (Amphipoda: Gammaridae) to act as efficient diluters of echinostome cercariae (Echinoparyphium aconiatum Dietz, 1909 [Digenea: Echinostomatidae]); both the predators and the parasite are benthic organisms (Giari et al, 2020;Haas et al, 2008), often occurring sympatrically in European freshwater ecosystems.…”