Survival and swimming performance of a small-sized Cypriniformes (Telestes muticellus) tagged with passive integrated transponders

Italian riffle dace (Telestes muticellus, Bonaparte 1837) is a small-bodied Leuciscidae native to the Italian Peninsula, of which little is known about the ecology and individual movements in nature. Passive Integrated Transponder (PIT) telemetry is used to track fish movements and behaviour. The basic assumption is that the PIT-tagged organism's performances do not differ considerably from their natural behaviour. Here we present the first evaluation of potential tagging effects in the genus Telestes. The survival rate and tag retention were compared between two different tag implantation methods – injector gun and scalpel incision - and pit-tagging effects on swimming performance were evaluated. Five weeks after tagging, Italian riffle dace demonstrated high survival rates in all treatments: 94.8% for fish tagged with injector gun (n=58), 100% for scalpel incision method (n=58), and 98.3% for controls (n=58). The tag retention was 96.6% for gun treatment and 100% for scalpel treatment. Prolonged swimming performance, tested 22-23 days after tagging, showed a reduction in endurance (time-to-fatigue) for scalpel treatment (n=22) compared to the control group (n=21), while no difference in maximum swimming velocity was observed. We conclude that PIT tagging is a suitable technique for Italian riffle dace, showing high survival and PIT retention and no effect on maximum swimming speed. Significantly lower prolonged swimming performance, although likely less ecologically important, shows that tagging is not without costs. Potential biases need to be evaluated on a study-by-study basis, and future studies should explore behavioural tagging effects in nature

Survival and swimming performance of a small-sized Cypriniformes (Telestes muticellus) tagged with passive integrated transponders

Italian riffle dace (Telestes muticellus, Bonaparte 1837) is a small-bodied Leuciscidae native to the Italian Peninsula, of which little is known about the ecology and individual movements in nature. Passive Integrated Transponder (PIT) telemetry is used to track fish movements and behaviour. The basic assumption is that the PIT-tagged organism’s performances do not differ considerably from their natural behaviour. Here we present the first evaluation of potential tagging effects in the genus Telestes. The survival rate and tag retention were compared between two different tag implantation methods – injector gun and scalpel incision - and pit-tagging effects on swimming performance were evaluated. Five weeks after tagging, Italian riffle dace demonstrated high survival rates in all treatments: 94.8% for fish tagged with injector gun (n=58), 100% for scalpel incision method (n=58), and 98.3% for controls (n=58). The tag re-tention was 96.6% for gun treatment and 100% for scalpel treatment. Prolonged swimming performance, tested 22-23 days after tagging, showed a reduction in endurance (time-to-fatigue) for scalpel treatment (n=22) compared to the control group (n=21), while no difference in maximum swimming velocity was observed. We conclude that PIT tagging is a suitable technique for Italian riffle dace, showing high survival and PIT retention and no effect on maximum swimming speed. Significantly lower prolonged swimming performance, although likely less ecologically important, shows that tagging is not without costs. Potential biases need to be evaluated on a study-by-study basis, and future studies should explore behavioural tagging effects in natur

Trophic preferences of three allochthonous fishes in Bormida River (Alessandria, NW Italy)

The introduction of alien species is currently one of the greatest threats to biodiversity conservation. This is particularly true in river systems, where in recent years the growth of allochtonous or non-native species has increased dramatically. Numerous studies have investigated the presence and the distribution of invasive species, but few focused on the trophic habits of fish species introduced into new lotic environments. This paper provides information on the diet of three alien species in the Bormida River, a lotic system previously altered by chemical pollution. Barbus barbus shows a wide trophic spectrum, feeding mostly on benthic invertebrates but also consuming terrestrial arthropods, coarse particulate organic matter, filamentous algae and, more rarely, fish. Feeding activity of Pseudorasbora parva was mostly based on aquatic invertebrates but also algae and fine particulate organic matter was frequently ingested. Regarding diet analysis of Rhodeus amarus, fine detritus and algae were the most important components in the examined guts. There are significant potential overlaps with the trophic spectrum of native species

[First reporting of the signal crayfish (Decapoda, Astacidae) in the Province of Savona, Italy]

In this short note we report the sudden and numerically significant expansion of signal crayfish (P. leniusculus) from Piedmont towards Liguria. P. leniusculus (Decapode Astacidae) is native to northwestern America, introduced in Italy in 1981 in the province of Bolzano, a few years later it was reported in Brugneto Lake (Genova district) and during the 2009 in the Valla stream (Alessandria district). The peculiarities of this species, originally from "cold water", making it potentially invasive in the Apennine watercourses and also the presence of this allochthonous decapod in the Savona district, would like to suggest the implementation of containment plans, acts at least to limit its spread

Navigating the drought: upstream migration of a small-sized Cypriniformes (Telestes muticellus) in response to drying in a partially intermittent mountain stream

River flow intermittence is a natural phenomenon intensified by human activities, such as water abstraction and the effects of climate change. A growing number of rivers are predicted to experience intermittent flows, which may impact the diversity and abundance of freshwater species. Dry riverbeds directly diminish the availability of habitats for freshwater organisms, and suitable environments can turn into ecological traps with reduced survival rates, posing a significant threat to population persistence. Even though fish movements can enable drought-affected populations to persist, little is known about individual fish movement between intermittent and perennial reaches. Here, we study the movement of individual PIT-tagged Italian riffle dace (Telestes muticellus) in an intermittent and perennial river reach before, during and after two severe drying events. A high proportion of fish from the intermittent reach survived the drying riverbed through directed upstream migration. This was manifested in fish living in the intermittent reach of the river displaying significantly higher linear ranges, and net travelled distances during the monitoring period than fish in the perennial reach, which remained resident with limited linear range and net distances travelled. This finding underscores the importance of conserving longitudinal river connectivity in the face of increased water scarcity and intermittent flow patterns

Taxonomic and functional responses of macroinvertebrate communities to dam construction in a non-wadeable river

Damming and impoundment are among the main flow-related alterations in rivers worldwide. However, compared to the highland river sections where the impacts associated with dams have been largely studied, still scarce evidence is available in scientific literature for large, lowland rivers. In this study, the ecological effects of a hydropower dam in the Po River (Italy) on the taxonomic and functional responses of benthic macroinvertebrates were examined by comparing one station upstream of the dam with one downstream station over a six-year period. Weak and not significant differences were observed for taxon richness, abundance and community composition. By contrast, community-level proportion of macroinvertebrates associated with water velocity increased during medium and high flow condition and decreased during low flow condition in downstream stations. Such differences were also mirrored by the Flow-T index, that is a biomonitoring index recently developed to assess hydraulic conditions in rivers. Results of this study support the adoption of stressor-specific metrics in river biomonitoring

Reptiles in the diet of a <em>Oncorhynchus mykiss</em> (Osteichthyes: Salmonidae) naturalized population in Piedmont (N Italy)

The authors report on predation by salmonid fish on some reptile species in two tributaries of the Tanaro river in the Alessandria province (NW Italy). The remains of Podarcis muralis, Anguis fragilis and of an undetermined colubrid of the genus Natrix were found in bromatological analyses performed on 117 <em>Oncorhynchus mykiss</em> specimens. Salmonid predation on herpetofauna once again confirms the alimentary opportunism of these fishes; however, predation is an occasional phenomenon and not a threat to the local reptile populations

PIT-tagging Italian spined loach (Cobitis bilineata): Methodology, survival and behavioural effects

The Italian spined loach (Cobitis bilineata) is an elongated, small-sized (<12 cm) spined loach native to northern Italy, Slovenia and Croatia. As for loaches in general, little is known about the individual movements of this loach in nature. Passive integrated transponders (PIT-tags) are small (typically 7-32 mm), relatively cheap and allow tracking of individual fish movements and behaviour. A fundamental assumption in animal telemetry is that the performance of a tagged animal does not deviate substantially from its natural performance. Although PIT-tagged fish often display high survival and tag retention, the effect varies between species and contexts, and few studies have looked at behavioural effects of PIT-tagging. Here we demonstrate a PIT-tagging methodology for spined loaches, and compare survival, activity and provoked escape response (maximum swimming speed) between tagged and control fish. We also track tag retention in the tagged fish. Italian spined loaches tagged with 12 mm PIT-tags displayed high tag retention and no extra mortality, and no effects of tagging on activity or maximum swimming speed were observed. The tag-to-fish weight and length ratios in our study ranged from 2% to 5% and from 10% to 16%, respectively, and we conclude that PIT-tagging, within these ratios, appears suitable for Italian spined loach