Search Results (17)

Various biological traits support the invasive success of different organisms. The osmoregulatory capacity and food preferences of the signal crayfish Pacifastacus leniusculus were experimentally tested to determine if they contribute to its invasive success. The osmotic concentrations of haemolymph were determined after acclimation of the crustaceans to seven salinities from 0 to 20 PSU. Food preferences were tested using Canadian pondweed Elodea canadensis, and rainbow trout Oncorhynchus mykiss. The results showed that the signal crayfish exhibits a hyper-hypoosmotic regulation pattern in the salinity range from 0 to 20 PSU, enabling them to inhabit both freshwater and brackish environments. Furthermore, the study found signal crayfish to have non-specific food preferences, although fish muscle tissue is more beneficial as a source of energy. Both features, osmoregulatory ability and food preferences, can increase the invasive success of this species as it expands into new areas. The ability to survive in higher salinities compared to the coastal waters of the Baltic Sea along the Polish coastline should be considered in targeted management strategies to control the spread of this invasive species. Full article

A circular economy aims at decoupling value creation from waste generation and resource use. The signal crayfish Pacifastacus leniusculus is kept worldwide in aquaculture and after escaping into the wild, may further be used for human consumption rather than eradicated and used for purposes such as fertilizing fields. The level of contamination by two groups of persistent organic pollutants (POPs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), in non-native signal crayfish from a Baltic coastal river, was measured in two locations (under anthropogenic pressure and semi-natural pressure) to understand whether its consumption might be a threat to human health. Concentrations of indicators and total compounds of POPs in the edible parts of crayfish (muscular tissue of crayfish) with potential human health risks were determined. The levels of concentrations of POPs meet the requirements of Regulations (EU) No. 836/2011 and No. 1259/2011 for the consumption of crustaceans. Our results also indicate no significant public health risk caused by consumption of the signal crayfish (hazard quotients (HQ) < 1). The results show that the bioaccumulation of POPs depends on the species’ traits and environment. Full article

The signal crayfish Pacifastacus leniusculus is one of the most widespread non-indigenous crayfish in Europe and is of interest to aquaculture in many countries. Once they escape into the wild, they disperse and become a potential source of food exploited for consumption by local inhabitants. The ingestion of plastics by the invasive signal crayfish in the Wieprza River, a tributary to the Baltic Sea, was determined by the FTIR identification of plastic compounds found in stomachs. The occurrence of plastic debris in the stomachs of P. leniusculus is reported for the first time. Plastic particles with the size range between 70 and 450 µm were observed only among crayfish inhabiting the lower, urbanized part of the river (7.3% of specimens). The presence of PTFE (polytetrafluoroethylene), cellophane, PP (polypropylene), PE (polyethylene), PMMA (polymethyl methacrylate), and nylon was confirmed with the highest frequency of PTFE in the stomachs of crayfish. Fibres were the predominant type of microplastics in crayfish stomachs. The results indicated the size-selective uptake and ingestion of plastics depending on the traits of the species and environment. Full article

Invasive non-indigenous crayfish species (NICS) are a major threat to the existence of native crayfish populations in European freshwater ecosystems. The discovery of signal crayfish Pacifastacus leniusculus, marbled crayfish Procambarus virginalis, and spiny-cheek crayfish Faxonius limosus in Estonia has increased the risk of extinction of Estonia’s only native crayfish species, the noble crayfish Astacus astacus. The aim of this study was to give an overview of the status, distribution, and impacts of P. leniusculus, F. limosus, and Procambarus virginalis on A. astacus populations and assess the effect of trapping on NICS abundance. Annual monitoring of crayfish has been carried out since 2008 as part of A. astacus conservation and the NICS eradication plan. In this study, we present data from nine sampling locations monitored from 2010 to 2022. The spread of NICS continues to increase beyond their distribution areas, and in two sampling locations P. leniusculus and A. astacus live in sympatry. Our results suggest that trapping has a limited effect on population abundance, as NICS have already caused the extinction of two A. astacus populations. However, intensive trapping should continue simultaneously with sensitive molecular techniques to monitor the spread of NICS. Full article

Increased anthropogenic carbon dioxide (CO₂) in the atmosphere can enter surface waters and depress pH. In marine systems, this phenomenon, termed ocean acidification (OA), can modify a variety of physiological, ecological, and chemical processes. Shell-forming organisms are particularly sensitive to this chemical shift, though responses vary amongst taxa. Although analogous chemical changes occur in freshwater systems via absorption of CO₂ into lakes, rivers, and streams, effects on freshwater calcifiers have received far less attention, despite the ecological importance of these organisms to freshwater systems. We exposed four common and widespread species of freshwater calcifiers to a range of pCO₂ conditions to determine how CO₂-induced reductions in freshwater pH impact calcium carbonate shell formation. We incubated the signal crayfish, Pacifastacus leniusculus, the Asian clam, Corbicula fluminea, the montane pea clam, Pisidium sp., and the eastern pearlshell mussel, Margaritifera margaritifera, under low pCO₂ conditions (pCO₂ = 616 ± 151 µatm; pH = 7.91 ± 0.11), under moderately elevated pCO₂ conditions (pCO₂ = 1026 ± 239 uatm; pH = 7.67 ± 0.10), and under extremely elevated pCO₂ conditions (pCO₂ = 2380 ± 693 uatm; pH = 7.32 ± 0.12). Three of these species exhibited a negative linear response to increasing pCO₂ (decreasing pH), while the fourth, the pea clam, exhibited a parabolic response. Additional experiments revealed that feeding rates of the crayfish decreased under the highest pCO₂ treatment, potentially contributing to or driving the negative calcification response of the crayfish to elevated pCO₂ by depriving them of energy needed for biocalcification. These results highlight the potential for freshwater taxa to be deleteriously impacted by increased atmospheric pCO₂, the variable nature of these responses, and the need for further study of this process in freshwater systems. Full article

The project “Recovery and Protection of Margaritifera margaritifera” (POSEUR-03-2215-FC-000096) was developed to protect and restore freshwater pearl mussel M. margaritifera and brown trout S. trutta populations in Portugal. To conduct this, in the last 3 years, several in situ and ex situ conservation measures were applied, and several tasks were defined, namely the following: (1) assessment of the spatial distribution and conservation status of the target species; (2) evaluation of the biological and ecological quality of salmonid rivers; (3) analysis of vulnerability to human disturbances; (4) an increase in habitat suitability; (5) definition of management plans for salmonid watercourses; 6) captive reproduction of M. margaritifera and S. trutta; (7) monitoring of M. margaritifera and S. trutta stocking programs; (8) genetic characterization of wild populations of S. trutta. Results showed that M. margaritifera is currently distributed in seven rivers (mainly in Rabaçal and Tuela rivers, and residually in Mente, Paiva, Neiva, Tâmega and Beça rivers). In Portugal, only S. trutta functions as a suitable host for M. margaritifera. Both species are highly vulnerable to human disturbances and the main threats include habitat fragmentation and degradation (e.g., dams and alder tree disease), invasive alien species (e.g., American crayfishes, Pacifastacus leniusculus and Procambarus clarkii) and climate change (e.g., droughts and heatwaves). A riparian area of 2.91 ha was restored, and several management plans were specifically developed in different rivers to contribute to the recovery of both native populations. Moreover, the ex situ reproduction of M. margaritifera produced more than 100,000 juveniles, allowing the implementation of reintroduction actions. Complementarily, eight wild brown trout stocks were selected, based on the genetic diversity, and acclimated to captivity in ICNF fishfarms (Castrelos, Bragança and Torno, Amarante) for future stocking programs according to national legislation. Overall, this project is a first step to improve the conservation status of pearl mussel M. margaritifera and its fish host, brown trout S. trutta. Full article

The spread of invasive crayfish species is a major threat to endemic species worldwide. This threat affects native crayfish as well as flora and fauna species in general. In order to limit their dispersal, different methods have been used, the most promising of which are those related to physical barriers. For their design, it is essential to know the limits in the capacity of crayfish to move under different hydraulic scenarios, although to date, there are few studies on this topic. The present work analyzes the volitional upstream movement capacity of the signal crayfish (Pacifastacus leniusculus) in a laboratory open flume, with different configurations of environmental and hydraulic variables (bed roughness, flow velocity, water temperature, times of day) and accounting for the possible effect of biometric factors (carapace length, sex). Twenty-four different trials with five individuals per trial were carried out, tracking all crayfish movements individually by visual tags and with a video monitoring system. Data were analyzed using survival analysis techniques and parametric models were developed, considering as response variables the maximum distance traveled and the movement speed. The results showed that the combination of bed roughness and flow velocity were the best predictors to explain crayfish movement performance, with a flow velocity greater than 0.8 m/s together on a non-rough bed being the limiting factor; the water temperature and the sex also have a significant effect. This information can serve as a basis for the design of future barriers to the dispersal of invasive crayfish species in the Iberian Peninsula. Full article

Here, we report, for the first time, a microsporidian infection in laboratory-reared larvae of the damselfly Ischnura elegans. Infected larvae originated from field-collected adult females, which were caught in southern Poland in August 2020 (the second half of the flight season). Higher rearing temperatures and the presence of predator cues from the invasive alien signal crayfish (Pacifastacus leniusculus) increased the number of infected larvae. Infected larvae had distorted wing development, and all individuals died before emergence. Hence, microsporidian infection in I. elegans larvae impacted damselfly morphology and life history. We propose that warming temperature and stress caused by non-consumptive effects triggered by invasive alien predators are possible factors that produce negative fitness consequences following microsporidian infection in a key amphibious ectotherm. Full article

Invasive crayfish are among the major threats to freshwater ecosystems, with the signal crayfish, Pacifastacus leniusculus, being one of the most successful crayfish invaders in Europe. Approaches to invasive crayfish control range from manual and physical to biological and biocidal control methods. However, all of these approaches have their drawbacks and have limited efficacy. Among traditional approaches with minimal impacts on environment and non-target species, manual control via trapping is the most frequently applied. More innovative approaches comprise, among others, usage of sterile male release technique, whose efficacy in the field is yet to be fully tested, especially how it combines with more traditional approaches. A good alternative to costly and logistically challenging field comparisons of these approaches and their combinations is population modeling. Population models can integrate all relevant species-specific biological and ecological information and can be applied to identify management scenarios of highest impact on invasive crayfish abundances. In this study, we developed a conceptual population model of the invasive P. leniusculus following the Pop-GUIDE framework. In addition, we expanded on the framework to increase its applicability to other fields beyond environmental risk assessment. Finally, we discuss potential application of the model and its future use as a management tool. Full article

Crayfish are a keystone species of freshwater ecosystems and a successful invasive species. However, their pathogens, including viruses, remain understudied. The aim of this study was to analyze the virome of the invasive signal crayfish (Pacifastacus leniusculus) and to elucidate the potential differences in viral composition and abundance along its invasion range in the Korana River, Croatia. By the high-throughput sequencing of ribosomal RNA, depleted total RNA isolated from the crayfish hepatopancreas, and subsequent sequence data analysis, we identified novel and divergent RNA viruses, including signal crayfish-associated reo-like, hepe-like, toti-like, and picorna-like viruses, phylogenetically related to viruses previously associated with crustacean hosts. The patterns of reads abundance and calculated nucleotide diversities of the detected viral sequences varied along the invasion range. This could indicate the possible influence of different factors and processes on signal crayfish virome composition: e.g., the differences in signal crayfish population density, the non-random dispersal of host individuals from the core to the invasion fronts, and the transfer of viruses from the native co-occurring and phylogenetically related crayfish species. The study reveals a high, previously undiscovered diversity of divergent RNA viruses associated with signal crayfish, and sets foundations for understanding the potential risk of virus transmissions as a result of this invader’s dispersal. Full article

The potential invasiveness of alien macroinvertebrate species in the Italian/Swiss hydrographic system of Lake Maggiore (NW Italy) was assessed through the Aquatic Species Invasiveness Screening Kit, a risk assessment tool developed for quantifying the impacts of alien species on the commercial, environmental, and species traits sectors. Data were collected using the databases provided by two regional environmental agencies in northern Italy (Lombardy and Piedmont regions) and by the governmental monitoring program of Switzerland, which were integrated with a systematic literature search on Google scholar and ISI Web of Science. In the assessment area, 16 macroinvertebrate invasive alien species were reported: nine mollusks, four decapods, and three amphipods. The species assessment indicated seven species with a high level of invasiveness: Procambarus clarkii, Faxonius limosus (formerly, Orconectes limosus) and Pacifastacus leniusculus, Dreissena polymorpha, Corbicula fluminea, Sinanodonta woodiana, and Pseudosuccinea columella. The results allow invasive species managers to understand which species to focus their monitoring on in the near future in order to track IAS movements and limit their spread within the hydrographic system and to provide the identification and refinement of concerted bilateral strategies aimed at limiting the impacts of these species. They also account for the implications of future climate change on the invasion potential of each species. Full article

Early changes in hemocyte proteins in freshwater crayfish Pacifastacus leniusculus, in response to an injection with the fungal pattern recognition protein β-1,3-glucan (laminarin) were investigated, as well as changes after saline (vehicle) injection and in naïve animals. Injection of saline resulted in rapid recruitment of granular hemocytes from surrounding tissues, whereas laminarin injection on the other hand induced an initial dramatic drop of hemocytes. At six hours after injection, the hemocyte populations therefore were of different composition. The results show that mature granular hemocytes increase in number after saline injection as indicated by the high abundance of proteins present in granular cell vesicles, such as a vitelline membrane outer layer protein 1 homolog, mannose-binding lectin, masquerade, crustin 1 and serine protease homolog 1. After injection with the β-1,3-glucan, only three proteins were enhanced in expression, in comparison with saline-injected animals and uninjected controls. All of them may be associated with immune responses, such as a new and previously undescribed Kazal proteinase inhibitor. One interesting observation was that the clotting protein was increased dramatically in most of the animals injected with laminarin. The number of significantly affected proteins was very few after a laminarin injection when compared to uninjected and saline-injected crayfish. This finding may demonstrate some problematic issues with gene and protein expression studies from other crustaceans receiving injections with pathogens or pattern recognition proteins. If no uninjected controls are included and no information about hemocyte count (total or differential) is given, expressions data for proteins or mRNAs are very difficult to properly interpret. Full article

Invasive alien species are a major threat to biodiversity. Thus, it is fundamental to implement control strategies at the early stages of invasions. In the framework of the Italian-Swiss Alien Invasive Species in Lake Maggiore cooperative programme, we performed an extensive study on the occurrence and ecology of alien crayfish, one of the most significant invaders of freshwater habitats. From April 2017 to July 2018, we inspected seventy-five sites along the coastline to verify crayfish occurrence. We recorded, for the first time, the signal crayfish Pacifastacus leniusculus. Additionally, we found few individuals and remains of the red swamp crayfish Procambarus clarkii, and confirmed the presence of a consistent population of the spinycheek crayfish Orconectes limosus. Given the high number of O. limosus’ individuals found, it was possible to perform in-depth biometric and ecological analyses for this abundant species only. We observed no significant differences of biometric measures between males and females of O. limosus. We explore its habitat preferences with a generalized linear model, detecting a significant relationship between mean annual temperatures and the presence of shelters of this species. These results, together, have direct implications for planning rapid management response actions on alien crayfish in large and deep lakes. Full article

Methamphetamine (METH), a central nervous system stimulant used as a recreational drug, is frequently found in surface waters at potentially harmful concentrations. To determine effects of long-term exposure to environmentally relevant levels on nontarget organisms, we analysed cardiac and locomotor responses of signal crayfish Pacifastacus leniusculus to acute stress during a 21-day exposure to METH at 1 μg L⁻¹ followed by 14 days depuration. Heart rate and locomotion were recorded over a period of 30 min before and 30 min after exposure to haemolymph of an injured conspecific four times during METH exposure and four times during the depuration phase. Methamphetamine-exposed crayfish showed a weaker cardiac response to stress than was observed in controls during both exposure and depuration phases. Similarly, methamphetamine-exposed crayfish, during METH exposure, showed lower locomotor reaction poststressor application in contrast to controls. Results indicate biological alterations in crayfish exposed to METH at low concentration level, potentially resulting in a shift in interactions among organisms in natural environment. Full article

This study focuses on the use of crayfish as bioindicators in the water treatment process during operating conditions. The crayfish physiological responses to water disinfected with chlorine dioxide (ClO₂) was evaluated. Monitoring was conducted at the private commercial enterprise Protivín Brewery in Czech Republic under standard operating conditions. This brewery has a water treatment facility, where ClO₂ is used for water purification. A total of 25 adult signal crayfish (Pacifastacus leniusculus) were kept in separate flow-through aquaria receiving the purified water with ClO₂ concentrations ranging from 0.01 to 0.29 mg L⁻¹. Diurnal rhythms of 32% of crayfish was disturbed even at lower concentrations of ClO₂ (0.01–0.2 mg L⁻¹), while higher concentrations (>0.2 mg L⁻¹) affected all animals. A random decline and rise of heart rate was detected. In addition, the frequent occurrence of higher levels of ClO₂ significantly increased mortality. On average, mortality of crayfish occurred three to four weeks after stocking into the experimental system. Crayfish mortality is estimated to occur at concentrations exceeding 0.2 mg L⁻¹ of ClO₂. Our results suggest that long-term exposure to ClO₂ adversely affects crayfish physiology. In addition, the results of this study could contribute to the use of crayfish as bioindicators in long-term water quality monitoring under industrial conditions. Full article