Patterns and processes influencing helminth parasites of Arctic coastal communities during climate change

Abstract

This review analyses the scarce available data on biodiversity and transmission of helminths in Arctic coastal ecosystems and the potential impact of climate changes on them. The focus is on the helminths of seabirds, dominant parasites in coastal ecosystems. Their fauna in the Arctic is depauperate because of the lack of suitable intermediate hosts and unfavourable conditions for species with freeliving larvae. An increasing proportion of crustaceans in the diet of Arctic seabirds would result in a higher infection intensity of cestodes and acanthocephalans, and may also promote the infection of seabirds with non-specific helminths. In this way, the latter may find favourable conditions for colonization of new hosts. Climate changes may alter the composition of the helminth fauna, their infection levels in hosts and ways of transmission in coastal communities. Immigration of boreal invertebrates and fish into Arctic seas may allow the circulation of helminths using them as intermediate hosts. Changing migratory routes of animals would alter the distribution of their parasites, facilitating, in particular, their trans-Arctic transfer. Prolongation of the seasonal 'transmission window' may increase the parasitic load on host populations. Changes in Arctic marine food webs would have an overriding influence on the helminths' circulation. This process may be influenced by the predicted decreased of salinity in Arctic seas, increased storm activity, coastal erosion, ocean acidification, decline of Arctic ice, etc. Greater parasitological research efforts are needed to assess the influence of factors related to Arctic climate change on the transmission of helminths.

Parasites of seabirds: A survey of effects and ecological implications

“…Helminths are a group of worms that are often parasitic in birds and include flatworms-which further separate into cestodes (tapeworms) and trematodes (flukes)-nematodes (roundworms), and acanthocephala (thornyheaded worms; Galaktionov, 2017;Galaktionov and Bustnes, 1995). The life cycle and transmission pathways of helminths are often complex, with both direct transmission (i.e.…”

“…Cestodes and trematodes (Phylum Platyhelminthes) are characterised by their lack of a body cavity, hermaphroditism, and the use of suckers (borthridia) to attach themselves within their host (Galaktionov, 2017). Flatworms can be most easily distinguished by the segmentation in their bodies; trematodes have unsegmented, smooth bodies, whereas cestodes have segmented bodies (Galaktionov, 2017). The lifecycle of trematodes and cestodes often involves two, sometimes three, intermediate hosts (e.g.…”

“…The lifecycle of trematodes and cestodes often involves two, sometimes three, intermediate hosts (e.g. copepod infected by feeding on cestode eggs, which in turn are ingested by cephalopods or fish) before reaching maturity within a seabird (Galaktionov, 2017). However, only trematodes require the obligatory participation of molluscs to complete their lifecycle (Galaktionov, 2017).…”

“…The diversity of cestodes and trematodes has been shown to vary across a host species range. For example, birds inhabiting the southern extent of the Common Eider (Somateria mollissima) range in the North Sea have as many as 15 trematode species, whereas at the northern extent of the range in Franz Josef Land, only a single trematode species has been reported (Galaktionov, 1996(Galaktionov, , 2017. In terms of the impact of these worms on seabird health and condition, as for most macroparasites, it is expected that negative impacts may only occur at very high parasite loads (see Galaktionov, 1996), but detailed studies in seabirds are limited and difficult to attribute to cestodes and trematodes in particular.…”

“…There is already evidence to suggest increased parasitism in northern wildlife due to changing climatic conditions (Brooks and Hoberg, 2007;Kutz et al, 2009Kutz et al, , 2014. Additionally, novel parasites may extend their ranges in polar regions, or potentially expand to new hosts introducing new interactions within ecosystems (Davidson et al, 2011;Galaktionov, 2017).…”