The Red Alien vs. the Blue Destructor: The Eradication of Cherax destructor by Procambarus clarkii in Latium (Central Italy)

Cherax destructor is a crayfish endemic to south-eastern Australia and one of the last alien crayfish to be introduced in Italy. In the Laghi di Ninfa Natural Reserve (Latium region, Central Italy), the species was probably introduced in 1999, but only reported for the first time in 2008. Nearby this area, the most widespread alien crayfish is the red swamp crayfish Procambarus clarkii. In the Natural Reserve, between 2008 and 2013 and during spring and summer, crayfish sampling was carried out with baited traps to assess the distribution of C. destructor and its possible relationship with P. clarkii. Cherax destructor was first recorded in 2008; few P. clarkii were detected in the cultivation ponds where C. destructor was present in 2012 and 2013. Moreover, crayfish plague analyses evidenced a positive result in two out of the 12 sampled P. clarkii. Cherax destructor is now completely absent from the Natural Reserve, while P. clarkii has spread in the area and was probably responsible for this eradication since C. destructor is vulnerable to crayfish plague which was also detected in the area. An ecosystem restoration project in the area favoured the spread of. P. clarkii; the implications of this intervention are discussed.

Muscle and carapace tissue–diet isotope discrimination factors for the freshwater crayfish Cherax destructor

This study examined a range of diets and two tissue types (muscle and carapace, representing protein and chitin biochemistry respectively) of Cherax destructor (Clark, 1936) to allow more accurate use of isotope data in trophic source estimates. The resulting Δ13Ctissue–diet and Δ15Ntissue–diet discrimination factors of muscle and carapace tissues showed significant differences among diets. For muscle, Δ13Ctissue–diet was higher (2.11–2.33‰) when C. destructor was fed with lamb, turkey and mixed animal and plant-based diets, 1.27–1.96‰ when C. destructor was fed with beef and kangaroo diets and negative (–1.36‰) when C. destructor was fed with an aquatic meat (tuna) diet. The Δ15Ntissue–diet discrimination factors were lower for muscle when C. destructor was fed aquatic meat (0.12‰) and mixed plant–animal diets (1.67‰), but higher for terrestrial meat diets (2.79–3.74‰). The Δ13Ctissue–diet for carapace followed similar patterns to that of muscle, but Δ15Ntissue–diet values were lower for carapace than muscle. Strong correlations were observed between muscle and carapace for δ13C (r=0.96, P<0.0001) and δ15N (r=0.82, P<0.0012) across the six diets evaluated, indicating that carapace can be used as a non-lethal alternative to muscle during field sampling.

First reports of per- and poly-fluoroalkyl substances (PFASs) in Australian native and introduced freshwater fish and crustaceans

Per- and poly-fluoroalkyl substances (PFASs) are persistent organic pollutants that have been extensively used in commercial and industrial applications, such as aqueous film-forming foam (AFFF) formulations. Widespread use of AFFFs has led to an increasing number of reports documenting PFAS contamination around civilian and military airports. However, research on the presence and distribution of PFASs in Australia is lacking. This study presents the first report of PFASs in Australian native and introduced freshwater species, sampled from a watercourse adjacent to the regional airport and colocated fire training ground near Tamworth, New South Wales, Australia. Perfluorooctane sulfonate was the most abundant PFAS compound in biota samples from this area, and both introduced common carp Cyprinus carpio and native Murray cod Maccullochella peelii had average concentrations higher than the Australian trigger value of 5.2μgkg–1. Common yabby Cherax destructor and golden perch Macquaria ambigua carried low concentrations, and common yabby also had low concentrations of perfluorohexane sulfonate. Differences in foraging habits provided some potential explanations of the differences observed among species. There is a clear and pressing need to better understand potential toxicological and reproductive effects of PFASs on Australian freshwater species.