Faiad, 2022

Faiad S. 2022. Under what conditions can a novel invader (the marbled crayfish, Procambarus fallax f. virginalis) exert predation pressure on schistosome-competent snails? Master's thesis, School of Aquatic and Fisheries Sciences, University of Washington. http://hdl.handle.net/1773/49377

 

Abstract

 

The human burden of environmentally transmitted infectious diseases can depend strongly on ecosystem factors, including the presence or absence of natural enemies. Like natural enemies, non-native species influence the abundance and distribution of their prey and competitors, yet the impact of these invaders on the transmission of diseases remains largely unexplored. One environmentally transmitted infectious disease with potential to be influenced by natural enemies is schistosomiasis, a parasitic disease infecting over 200 million people across South America, Asia, and Africa. The marbled crayfish (Procambarus fallax f. virginalis) first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of Schistosoma spp. worms. Marbled crayfish can tolerate a wide range of ecological conditions, colonize diverse habitats, and may serve as an enemy of schistosome-competent snails in areas where natural predators cannot–something that is urgently needed in a country where schistosomiasis prevalence in some villages can range up to 94%. Here, I experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. Crayfish consumption was significantly influenced by crayfish weight, as well as the interaction between weight and temperature. Compared to small crayfish, large crayfish experienced a greater increase in consumption at moderate temperatures (25 and 30°C) relative to extreme temperatures (15, 20, and 35 °C). The temperature at which the rate of consumption was highest (i.e., the thermal optimum) was estimated to be 31.1 °C for small crayfish (<3.90 g), 27.7 °C for medium crayfish (3.91 – 6.62 g), and 28.7 °C for large crayfish (> 6.3 g). Neither snail species nor snail infection status were significantly associated with consumption. My results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential regulatory impact of the marbled crayfish on snail host populations.

Brown and Therriault 2022

Brown NEM, Therriault TW. 2022. The hidden risk of keystone invaders in Canada: a case study using non-indigenous crayfish. Canadian Journal of Fisheries and Aquatic Sciences 79(9): 1479-1496. https://doi.org/10.1139/cjfas-2021-0245

 

Abstract

Invasive species have long been recognized as a serious threat to freshwater ecosystems. This is especially true for invasive species in keystone positions in food webs that can cause major disruption and can lead to unexpected outcomes. Crayfish occupy a central trophic position and non-indigenous crayfish have been shown to substantially disrupt ecosystems they invade. Here, we assess eight non-indigenous crayfish to 21 freshwater ecoregions in Canada using a screening-level risk assessment. We found that ecoregions in Canada that were warmer and contained high native freshwater diversity were most at risk from crayfish invasions, particularly: the Laurentian Great Lakes, St. Lawrence, English-Winnipeg Lakes and Coastal British Columbia ecoregions. Four crayfish species consistently had higher scores: rusty (Faxonius rusticus), virile (Faxonius virilis), signal (Pacifastacus leniusculus), and red swamp (Procambarus clarkii). Of these high-risk crayfish, only the red swamp crayfish is not yet established in Canada but is present in US waters of the transboundary Great Lakes ecoregion. Our study is the first to evaluate the relative risks that non-indigenous crayfish pose to freshwater ecosystems in Canada.

 

Keywords: None provided.

Bláha and colleagues 2022

Bláha M, Weiperth A, Patoka J, Szajbert B, Balogh ER, Staszny Á, Ferincz Á, Lente V, Maciaszek R, Kouba A. 2022. The pet trade as a source of non-native decapods: the case of crayfish and shrimps in a thermal waterbody in Hungary. Environmental Monitoring and Assessment 194(10): 795. https://doi-org.libaccess.lib.mcmaster.ca/10.1007/s10661-022-10361-9

Abstract

Ornamental aquaculture and the related pet industry are known to be important sources of non-native species worldwide. In the temperate zone, thermal waterbodies are attractive places for irresponsible owners to release unwanted freshwater pets including decapod crustaceans. Several non-native ornamental species have been reported in the thermal locality of Miskolctapolca (a suburb of Miskolc, Hungary). So we surveyed this site in March 2019–November 2021 to update local occurrence records and detect potentially newly released species. A well-established population of Neocaridina denticulata and the occurrence of Caridina cf. babaulti had previously been noted. However, for the first time at this site, we found the shrimps Atyopsis moluccensis, Caridina gracilirostris and C. multidentata, as well as the crayfish Procambarus virginalis, P. clarkii, Cherax quadricarinatus, C. boesemani and C. snowden, and several formally undescribed Cherax species originating from New Guinea. Furthermore, in most species, gravid females carrying eggs were also noticed. Three shrimps, A. moluccensis, C. gracilirostris and C. multidentata, were recorded for the first time in European wild. Further monitoring of this locality and better education of the general public regarding the risks associated with the release of non-native species are strongly recommended.

 

Keywords: Ornamental species • invasive species • Decapoda • Europe • thermal water