Cross-species comparison of parasite richness, prevalence, and intensity in a native compared to two invasive brachyuran crabs

Abstract

Non-native populations of Pacific oysters Crassostrea gigas (Thunberg 1793) are established around the United Kingdom (UK), with two genetically different stocks originating from separate introductions to the UK and France. In this study, we use a coupled biophysical model to simulate Pacific oyster larval transport, in order to investigate the dispersal of the species from a known population near their northern limit on the west coast of the UK (in the Milford Haven Estuary). The model included a pelagic phase, simulating different swimming behaviours, and a settlement phase based on a hydrospatial substrate map. Following successful settlement elsewhere, subsequent releases simulated potential population spread over successive generations. Our results suggest that, should there be sufficiently warm sea temperatures to allow reproduction, dispersal away from Milford Haven Estuary would most be southeast ward towards the Bristol Channel; but dispersal north and west to Ireland is also possible, depending heavily on pelagic swimming behaviour. Seasonal modifications to circulation were less influential. Our study increases understanding of factors that contribute to oyster population spread, and suggests methods for improved management through numerical predictions.

Mechanisms of possible self-limitation in the invasive Asian shore crab Hemigrapsus sanguineus

“…Parasite infection may also play a role in limiting H. sanguineus success. This species is infected by both acanthocephalan and trematode parasites in its invaded range 48,74 , two groups of parasites that can impact the behavior and survival of crabs 75,76 . As highlighted in the Introduction, Asian shore crabs have fewer parasites in their invaded range than native species in the same area 47 and fewer parasites than conspecifics in their native range [46][47][48] .…”

Prey size selection in invasive (Hemigrapsus sanguineus and H. takanoi) compared with native (Carcinus maenas) marine crabs

“…The Asian shore crabs Hemigrapsus sanguineus and Hemigrapsus takanoi occur sympatrically with native shore crabs Carcinus maenas at coastal waters around the Dutch Wadden Sea island of Texel (Goedknegt et al ., 2017). Crabs of all three species were collected from the southern coast of Texel with baited traps and by hand in autumn 2017.…”

First record of the endoparasitic isopod Portunion maenadis (Giard, 1886) (Epicaridea: Entoniscidae) in shore crabs in the Wadden Sea and a review of its distribution in Europe

“…It is the first record for the Wadden Sea region and the second record for the North Sea as a whole aside from a specimen from the Firth of Forth in Scotland which stems from a private collection from approximately 1920/1930 which was integrated into the collection of the Natural History Museum London in 1958 (Natural History Museum 2019). Since then, there have been several parasitological studies on shore crabs (C. maenas) in the North Sea area, none of which observed P. maenadis (Goudswaard 1985;Stentiford and Feist 2005;Thieltges et al 2008;Blakeslee et al 2009;Zetlmeisl et al 2011;Goedknegt et al 2017;Bojko et al 2018). This indicates that the parasite is relatively rare and has a very patchy distribution on a regional scale.…”