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Trophic interactions are a critical component of ecosystem stability, governing prey-predator relationships. Crayfish are involved in numerous interactions within freshwater communities and, when non-native, they can negatively impact the structure and dynamics of ecosystems. During biotic interactions or unsuccessful molts, they are able to autotomize one or more claws, which can lead to changes in ecological performance among individuals. Because crayfish claws play an important role in feeding behavior, this creates an overlooked biotic context that could influence trophic interactions and impact on prey communities. It has been shown previously that crayfish claws have a minor role in predation of slow, soft prey, but their function concerning fast hard-bodied prey remains poorly studied. Here, we investigate whether the number of claws on marbled crayfish Procambarus virginalis modulates its ecological impact (focusing on predation rate) using functional response analyses against more mobile hard-bodied prey. We showed that the number of claws in P. virginalis significantly influenced the rate of predation on the prey Gammarus fossarum, with crayfish with two claws exhibiting a higher attack rate and lower handling time than clawless individuals. In addition, we found that non-trophic interactions increased with prey density, with generally antagonistic interactions between crayfish that reduced prey risk irrespective of claw presence. The influence of biotic contexts such as claw presence, prey density and prey type, as well as consumer density, should be considered in inferences of trophic and non-trophic interactions, as well as ecological impacts of invasive species. [ABSTRACT FROM AUTHOR]

The introduction of non-native fish species poses a significant threat to biodiversity. In Spain, the common carp Cyprinus carpio (Linnaeus, 1758) and the bleak Alburnus alburnus (Linnaeus, 1758) are both established and sometimes co-occurring non-native species. Here, we investigated the trophic ecology of these species using an integrative approach, combining dietary and stable isotope analyses, to understand seasonal variations in their feeding ecology and potential niche overlap. We found a variable pattern for the gonadosomatic index of the two species in spring and autumn, suggesting the occurrence of extended reproductive periods for both A. alburnus and C. carpio. The gut content and isotopic niche analyses showed seasonal niche shifts, as well as interspecific niche partitioning and potential feeding competition. Notably, we found remains of small fish in the gut of both species and one entire individual of Gambusia holbrooki (Girard, 1859) in the carp gut, highlighting the potential of both species to prey also upon native fish fry or juveniles. Moreover, A. alburnus showed an ontogenetic shift toward prey from higher trophic levels and from the littoral/benthic environment, while C. carpio showed an increase in the proportion of prey from the pelagic environment with size. [ABSTRACT FROM AUTHOR]

Biological invasions by amphibian and reptile species (i.e. herpetofauna) are numerous and widespread, having caused severe impacts on ecosystems, the economy and human health. However, there remains no synthesised assessment of the economic costs of these invasions. Therefore, using the most comprehensive database on the economic costs of invasive alien species worldwide (InvaCost), we analyse the costs caused by invasive alien herpetofauna according to taxonomic, geographic, sectoral and temporal dimensions, as well as the types of these costs. The cost of invasive herpetofauna totaled at 17.0 billion US$ between 1986 and 2020, divided split into 6.3 billion US$ for amphibians, 10.4 billion US$ for reptiles and 334 million US$ for mixed classes. However, these costs were associated predominantly with only two species (brown tree snake Boiga irregularis and American bullfrog Lithobates catesbeianus), with 10.3 and 6.0 billion US$ in costs, respectively. Costs for the remaining 19 reported species were relatively minor (< 0.6 billion US$), and they were entirely unavailable for over 94% of known invasive herpetofauna worldwide. Also, costs were positively correlated with research effort, suggesting research biases towards well-known taxa. So far, costs have been dominated by predictions and extrapolations (79%), and thus empirical observations for impact were relatively scarce. The activity sector most affected by amphibians was authorities-stakeholders through management (> 99%), while for reptiles, impacts were reported mostly through damages to mixed sectors (65%). Geographically, Oceania and Pacific Islands recorded 63% of total costs, followed by Europe (35%) and North America (2%). Cost reports have generally increased over time but peaked between 2011 and 2015 for amphibians and 2006 to 2010 for reptiles. A greater effort in studying the costs of invasive herpetofauna is necessary for a more complete understanding of invasion impacts of these species. We emphasise the need for greater control and prevention policies concerning the spread of current and future invasive herpetofauna. [ABSTRACT FROM AUTHOR]

Despite the potential ecological and economic impacts of invasive species, there is a dearth of data on the presence, impacts, and management implications of potentially invasive Orthoptera species. This lack of research and inconsistent data, including risk screenings and impact assessments, is especially evident in Europe. Consequently, assessing the status, distribution, and potential threats of nonnative Orthoptera in Europe remains challenging, impeding the development of effective management strategies. To address this gap, we call for increased efforts to collect and curate data on non‐native and possibly invasive Orthoptera in Europe. Such efforts will improve our understanding of this order's invasion dynamics, facilitate the identification of priority areas for conservation, and support the development of effective management policies and preventive measures. [ABSTRACT FROM AUTHOR]

Anthropogenic disturbances are having strong, negative effects on aquatic systems globally, altering ecological communities and potentially creating vacant niches for both native and non-native species (NNS). Globalization and new trade routes have amplified the spread and establishment of NNS by connecting disturbed areas worldwide. In this study, we conducted a comparative assessment of seasonal variations in amphipod communities at three southeastern Baltic Sea locations – two anthropogenically impacted and one protected habitat – to determine if native and NNS diversity differed among these habitats. Our study revealed nine amphipod species - of which two were NNS - across all three habitats. The impacted habitats had significantly higher native species richness and lower NNS abundance. Grandidierella japonica was the only NNS found at the impacted habitas. In the case of the protected habitat, NNS Gammarus tigrinus was dominant for most of the year. In autumn, dominance shifted in favour of the native Gammarus locusta and Microdeutopus cf. gryllotalpa. Grandidierella japonica was not detected there. Although anthropogenically impacted habitats may be under higher invasion risk, other environmental factors, such as salinity and temperature, may be driving the establishment pattern of NNS and the resulting community structures. Furthermore, undisturbed and/or protected habitats may be highly vulnerable to invasions due to more tolerable environmental conditions, robust NNS populations and naïve native species to newcomers. Seasonality is an important aspect of ecological studies and must be taken into account, as omissions could potentially distort our understanding of the dynamics of ecosystems and prevent the detection of NNS. [ABSTRACT FROM AUTHOR]

Stable isotope analysis has been broadly used to study food webs, but often relies on inaccurate assumptions of trophic isotopic discriminations, which could lead to misinterpretation of obtained results. While many taxa exhibit similar trophic discrimination factors (TDFs), crayfish, exhibit omnivorous feeding strategies, yet TDFs are missing. In this study, we determined TDFs and tissue biokinetic parameters of the marbled crayfish Procambarus virginalis as a model species. Moreover, we compared commonly used TDFs and those determined from this study and applied them across species and ecosystems as a first attempt to compare the effect of species-specific TDFs in Bayesian trophic mixing models. Our results revealed differences between the TDFs of different tissues and biokinetic parameters of crayfish. Our result also revealed TDFs differences between crayfish relying mostly on plants versus those relying on an animal diet. We found differences of TDF suitability among species and ecosystems, highlighting the need for specific TDFs for different crayfish species. This study improves our understanding and the need for species-calibrated TDFs for robust statistical analysis of stable isotope data. Our approach is widely applicable across taxa and ecosystems to reduce the bias introduced by using unspecific TDFs in Bayesian mixing models. [ABSTRACT FROM AUTHOR]

The concept of a standardized reference diet (SRD) is used in laboratory model organisms to ensure nutritional control between studies and laboratories. Although models using the genetically identical, all female parthenogenetic marbled crayfish (Procambarus virginalis) are growing in popularity, research into nutrition in this species still has many knowledge gaps. To fast track the development of a SRD in terms of protein and amino acids (SRDprotein) for this species, we first analyzed the composition of its body amino acids to determine the ideal protein concept (IPC) of indispensable amino acids in wild-caught P. virginalis (which had an unusually high preponderance of leucine and arginine). Then, we strategically evaluated three common clusters of types of fish feed: (1) ornamental fish feed (SER) fortified with a naturally occurring alga (Spirulina). This type of feed was protein-high in arginine and leucine (SER + SPI) that fulfils the species' IPC for iso-protein (~ 40%), iso-phosphorus (~ 0.8%) and near iso-energetic (~ 475 kcal 100 g−1); (2) freeze-dried live feed consisting of chironomid larvae (CHI) fortified with Spirulina (CHI + SPI) that fulfils the IPC for iso-protein (~ 46%), iso-phosphorus (~ 0.7%) and near iso-energetic (~ 405 kcal 100 g−1); and (3) a commercially standardized 'starter diet' for carnivorous fish larvae (FISH) and post-larval shrimps (SHRIMP) with iso-protein (~ 56%) and iso-phosphorus (~ 1.6%). A total of six diets, embracing a diverse range of proteinaceous feeds, were used in a 100-day ad libitum feeding and growth trial. The FISH group outperformed all the other groups (p < 0.05) and our exploratory multivariate analysis revealed an ideal demand of > 44% protein (tailored to deliver high arginine 3% and leucine 4%, followed by the usual lysine > 3.5% and methionine 1.2%) but also the lowest carbohydrate level (21%). For SRDprotein, our findings show that the FISH diet is ideal and suggest the possibilities of using a CHI + SPI diet for further optimization (more economic use of protein and phosphorus). [ABSTRACT FROM AUTHOR]

The zebra mussel Dreissena polymorpha is one of the most successful, notorious, and detrimental aquatic invasive non‐native species worldwide, having invaded Europe and North America while causing substantial ecological and socio‐economic impacts. Here, we investigated the spatiotemporal trends in this species' invasion success using 178 macroinvertebrate abundance time series, containing 1451 records of D. polymorpha collected across nine European countries between 1972–2019. Using these raw (absolute) abundance data, we examined trends and drivers of occurrences and relative abundances of D. polymorpha within invaded communities. Meta‐regression models revealed non‐significant trends both at the European level and for the majority of the invaded countries, except for France (significant decreasing trend) and Hungary (marginally positive trend). At the European level, the number of D. polymorpha occurrences over time followed a flat‐top bell‐shaped distribution, with a steep increase between 1973–1989 followed by a plateau phase prior to significantly declining post‐1998. Using a series of climatic and hydromorphological site‐specific characteristics of invaded and uninvaded sites from two periods (1998–2002; 2011–2015), we found that native richness, non‐native abundance, distance to the next barrier, and elevation were associated with the occurrence of D. polymorpha. We also found that higher native richness and lower latitude were related to lower relative abundances. Using Cohen's D as a measure of D. polymorpha impact, we found that biodiversity within the invaded sites was initially higher than in uninvaded ones, but then declined, suggesting differences in biodiversity trends across invaded and uninvaded sites. While our results emphasise the high invasion success of D. polymorpha, increasing stressors within the context of global change – particularly ongoing climate change – are likely to enhance invasion rates and the impact of D. polymorpha in the near future, exacerbated by the lack of timely and effective management actions. [ABSTRACT FROM AUTHOR]

The aquarium pet trade is a source of potentially invasive crayfish species, which can be subsequently intentionally or unintentionally introduced into new environments. This can lead to biological invasions that represent a threat to native biodiversity and, in particular, freshwater ecosystem functioning. In global terms, Europe is the most affected region, and invasive crayfish species are increasing in number, establishing their populations and expanding their ranges. Despite being similarly affected, the situation in Serbia (SE Europe) has remained overlooked in this regard. A survey of the aquarium pet trade in this country revealed six different crayfish species traded as ornamentals. Marbled crayfish Procambarus virginalisLyko, 2017, a well-known invader, was traded in more than half of the studied towns and cities in Serbia and is commonly available both in pet shops and through e-commerce (online selling). Other potentially invasive crayfish include the red swamp crayfish Procambarus clarkii (Girard, 1852) and the Florida crayfish Procambarus alleni (Faxon, 1884), both of which are already established in some European inland waters. The presence of invasive species in the aquarium pet trade in Serbia could theoretically lead to their occurrence in the wild. Given that, in terms of cost and feasibility, the best defence against biological invasions is prevention. A rapid response to the findings discussed here could be the key to prevent future invasions of Serbian freshwater ecosystems by non-native crayfish species. [ABSTRACT FROM AUTHOR]

In this study, we experimentally evaluated how the feeding behaviour of marbled crayfish Procambarus virginalis is influenced by cues from conspecifics and the round goby Neogobius melanostomus, a fish predator, in tanks that permitted chemical communication but not visual recognition. We used four experimental groups with different combinations in two sub-tanks. The first sub-tank always contained a crayfish and prey (40 individuals of the water louse Asellus aquaticus). The other sub-tanks were set up as follows: (i) empty, serving as a control (C); (ii) with a conspecific crayfish (Cr); (iii) with a round goby (G) to simulate predator-only odour; and (iv) a round goby and three small conspecific crayfish (G + Cr) to simulate the presence of a predator and/or the alarm odour. Two sub-treatments were defined for the fourth group, categorised as 'injured' or 'not injured' depending on whether prey crayfish were visibly injured or not, respectively. We observed a significant decline in the consumption of water lice in the G and G + Cr treatments compared to the C and Cr treatments (up to 47% on average). There were no significant differences in consumption between the G and G + Cr treatments, or C and Cr treatments. No significant differences in food consumption parameters were detected between sub-treatments with 'injured' and 'not injured' conspecific crayfish. Knowledge of modifications in the feeding behaviour of marbled crayfish in the presence of round goby (and fish predators in general) is essential for ecologists attempting to understand the changes and impacts occurring in invaded freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Crustacean hemocytes are important mediators of immune functions such as coagulation and phagocytosis. We employed an in situ approach to investigate the ultrastructural behavior of hemocytes during coagulation and phagocytosis in the early stages after injury caused by leg amputation, using transmission electron microscopy technique in marbled crayfish Procambarus virginalis. Hemocytes underwent drastic morphological changes during coagulation. The morphology of the cytoplasmic granules changed from electron-dense to electron-lucent forms in an expanding manner. The transformed granules containing amorphous electron-lucent material were observed to merge and discharge their contents into extracellular space for coagulation. We also observed that the contents of the nucleus participate in the process of coagulation. In addition, leg amputation induced extensive muscle degeneration and necrotic tissues were avidly taken up by the phagocytic hemocytes containing distinct phagosomes. Interestingly, we observed for the first time how the digested contents of phagocytized necrotic tissues are incorporated into granules and other cellular components that change the cell morphology by increasing the granularity of the hemocytes. Nevertheless, the degranulation of hemocytes during coagulation can also reduce their granularity. Given that morphological traits are important criteria for hemocyte classification, these morphological changes that occur during coagulation and phagocytosis must be taken into account. • Coagulation and phagocytosis extensively change the morphology of hemocytes. • During degranulation, electron-dense granules expand and transform into electron-lucent forms. • The contents of the hemocyte nucleus participate in coagulation. • Phagocytic hemocytes ingest and incorporate degenerated muscles that affect their granularity. [ABSTRACT FROM AUTHOR]

Aim: Invasive alien species are a growing problem worldwide due to their ecological, economic and human health impacts. The "killer shrimp" Dikerogammarus villosus is a notorious invasive alien amphipod from the Ponto‐Caspian region that has invaded many fresh and brackish waters across Europe. Understandings of large‐scale population dynamics of highly impactful invaders such as D. villosus are lacking, inhibiting predictions of impact and efficient timing of management strategies. Hence, our aim was to assess trends and dynamics of D. villosus as well as its impacts in freshwater rivers and streams. Location: Europe. Methods: We analysed 96 European time series between 1994 and 2019 and identified trends in the relative abundance (i.e. dominance %) of D. villosus in invaded time series, as well as a set of site‐specific characteristics to identify drivers and determinants of population changes and invasion dynamics using meta‐regression modelling. We also looked at the spread over space and time to estimate the invasion speed (km/year) of D. villosus in Europe. We investigated the impact of D. villosus abundance on recipient community metrics (i.e. abundance, taxa richness, temporal turnover, Shannon diversity and Pielou evenness) using generalized linear models. Results: Population trends varied across the time series. Nevertheless, community dominance of D. villosus increased over time across all time series. The frequency of occurrences (used as a proxy for invader spread) was well described by a Pareto distribution, whereby we estimated a lag phase (i.e. the time between introduction and spatial expansion) of approximately 28 years, followed by a gradual increase before new occurrences declined rapidly in the long term. D. villosus population change was associated with decreased taxa richness, community turnover and Shannon diversity. Main Conclusion: Our results show that D. villosus is well‐established in European waters and its abundance significantly alters ecological communities. However, the multidecadal lag phase prior to observed spatial expansion suggests that initial introductions by D. villosus are cryptic, thus signalling the need for more effective early detection methods. [ABSTRACT FROM AUTHOR]

In the current anthropogenic era characterised by human-induced environmental changes, long-term biomonitoring has become a crucial component for understanding ecological patterns and detecting shifts in biodiversity. However, spatiotemporal inconsistencies in biomonitoring efforts hinder transboundary progress in understanding and mitigating global environmental change effectively. The International Long-Term Ecosystem Research (ILTER) network is one of the largest standardised biomonitoring initiatives worldwide, encompassing 44 countries globally, including 26 European countries that are part of the European Long-Term Ecosystem Research network (eLTER). To better understand the establishment and development of such long-term biomonitoring efforts, we analysed spatial and temporal trends within the eLTER network. Additionally, we evaluated the environmental, social, and economic factors influencing engagement in biomonitoring activities within this European network. Our findings reveal a spatial imbalance, with biomonitoring efforts concentrated in Central and Western European countries, where monitoring initiatives have typically been established for a longer duration. Furthermore, our analyses underscore the complex interplay of economic, geographic, and cultural factors in the development of long-term ecological research infrastructures. Countries with greater geographic connectivity, slower economic growth, and higher research activity are more likely to be involved in the eLTER network. The intensity of biomonitoring significantly increased with greater research investments, economic growth, and elevated levels of tourism. In contrast, it decreased in countries that are more inward-facing and exhibit a belief in their ability to control environmental outcomes independently. Addressing spatial gaps in monitoring necessitates enhanced support and funding to ensure comprehensive ecological monitoring over extended time periods. This is essential for achieving transboundary sustainability and effective biodiversity conservation in the face of global change drivers. • Long-term biomonitoring essential for detecting biodiversity shifts. • Uneven biomonitoring distribution across Europe identified. • Central and Western Europe lead in monitoring initiatives. • Economic, geographic, cultural factors influence biomonitoring efforts. • Increased research investment boosts biomonitoring intensity. [ABSTRACT FROM AUTHOR]

Canals provide wide-ranging economic benefits, while also serving as corridors for the introduction and spread of aquatic alien species, potentially leading to negative ecological and economic impacts. However, to date, no comprehensive quantifications of the reported economic costs of these species have been done. Here, we used the InvaCost database on the monetary impact of invasive alien species to identify the costs of those facilitated by three major canal systems: the European Inland Canals, Suez Canal, and Panama Canal. While we identified a staggering number of species having spread via these systems, monetary costs have been reported only for a few. A total of $33.6 million in costs have been reported from species linked to European Inland Canals (the fishhook waterflea Cercopagis pengoi and the zebra mussel Dreissena polymorpha) and $8.6 million linked to the Suez Canal (the silver-cheeked toadfish Lagocephalus sceleratus, the lionfish Pterois miles, and the nomad jellyfish Rhopilema nomadica), but no recorded costs were found for species facilitated by the Panama Canal. We thus identified a pervasive lack of information on the monetary costs of invasions facilitated by canals and highlighted the uneven distribution of costs. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems worldwide are facing the establishment of non-native species, which, in certain cases, exhibit invasive characteristics. The impacts of invaders on native communities are often detrimental, yet, the number and spread of non-native invasive species is increasing. This is resulting in novel and often unexpected combinations of non-native and native species in natural communities. While the impact of invaders on native species is increasingly well-documented, the interactions of non-native invaders with other non-native invaders are less studied. We assessed the potential of an invasive amphipod, the killer shrimp Dikerogammarus villosus (Sowinsky, 1894), to cope with other established invaders in European waters: North American crayfish of the Astacidae family—represented by signal crayfish Pacifastacus leniusculus (Dana, 1852), and the Cambaridae family—represented by marbled crayfish Procambarus virginalis Lyko, 2017. The main goal of this study was to investigate if killer shrimp, besides their role as prey of crayfish, can significantly influence their stocks by predating upon their eggs, hatchlings and free-moving early juveniles. Our results confirmed that killer shrimp can predate on crayfish eggs and hatchlings even directly from females abdomens where they are incubated and protected. As marbled crayfish have smaller and thinner egg shells as well as smaller juveniles than signal crayfish, they were more predated upon by killer shrimp than were signal crayfish. These results confirmed that the invasive killer shrimp can feed on different developmental stages of larger freshwater crustaceans and possibly other aquatic organisms. [ABSTRACT FROM AUTHOR]

The spread of non-native species results in novel and often unexpected assemblages. Using stable isotopes, we disentangled the trophic relationships between three invasive crayfish species at two sites of a small thermal tributary of the Barát stream, Hungary. We studied Procambarus virginalis and Faxonius limosus living in sympatry in the upper section of this thermal tributary, and then an assemblage in a lower section also containing P. clarkii. The two species in the upper section largely shared trophic niches, although P. virginalis was more carnivorous than F. limosus, which fed more on detritus and aquatic plants. In the lower section, P. clarkii had a distinctive trophic niche, being more carnivorous than the other species and also preying on other crayfish and fish. The trophic niches of the other two species shifted slightly, being narrower and more overlapping in the presence of P. clarkii. It seems that the presence of P. clarkii affects the feeding habits and trophic niches of the other two crayfish. Our results also indicate that the species have somewhat distinctive feeding niches, which suggests that the ecosystem effects of these species are likely to be at least partially additive in the shared localities. [ABSTRACT FROM AUTHOR]

In most vertebrates, the development of a new individual starts with fertilization of the oocyte by the spermatozoon. A label-free quantification strategy was applied to investigate proteomic changes after fertilization and before first cleavage in the egg of rainbow trout. Samples were obtained from oocyte and fertilized eggs at 50, 200 min, and 15 h after fertilization at 4 °C. Significant changes were observed in the abundances of thirty-two proteins at different time points. The fertilization was accompanied by an upregulation of a coagulation factor protein which might be responsible for the construction of a layer for the protection of developing embryo. Upregulation of iron binding proteins such as ferritin and ceruloplasmin could reflect the importance of this metal ion in the fertilization. The quantity of complement which is known as an immunological protein significantly increased during early stages. Upregulation of kinase could reflect the potentials of the fertilized egg for protein phosphorylation. Importin and vitellogenin proteins showed both down- and upregulation patterns. The timing of the upregulation of three types of actins may indicate their potential roles in fertilization and development of the fertilized egg. Upregulation of proteins such as Kinesin-like protein, Sororin etc. by 15 h may contribute to the cell preparation for the division in the upcoming first cleavage. In conclusion, insemination causes extensive changes in the abundances of proteins which have potentials to conduct fertilization and the cell preparation for the first cleavage. Data are available via ProteomeXchange with identifier PXD013329. • The abundances of thirty-two proteins changed between post-ovulation and first cleavage. • Upregulation of a coagulation factor, ferritin and ceruloplasmin might be for the construction of a protective layer. • Importin and vitellogenin proteins showed both down- and upregulation patterns. • The timing of the upregulation of three types of actins may indicate potential roles in fertilization and development. • Upregulation of sororin and coiled-coil domain proteins may be necessary for the upcoming first cleavage. [ABSTRACT FROM AUTHOR]

The direct effects of temperature increases and differences among life-history might affect the impacts of native and invasive predators on recipient communities. Comparisons of functional responses can improve our understanding of underlying processes involved in altering species interaction strengths and may predict the effect of species invading new communities. Therefore, we investigated the functional responses of the mourning gecko Lepidodactylus lugubris (Duméril & Bibron, 1836) to explore how temperature, body-size and prey density alter gecko predatory impacts in ecosystems. We quantified the functional responses of juvenile and adult geckos in single-predator experiments at 20, 23 and 26 °C. Both displayed saturating Type-II functional responses, but juvenile functional responses and the novel Functional Response Ratio were positively affected by temperature as juvenile attack rates (a) increased as a function of increased temperature. Handling times (h) tended to shorten at higher temperature for both predator stages. We demonstrate that the effects of temperature on functional responses of geckos differ across ontogeny, perhaps reflecting life-history stages prioritising growth and maturation or body maintenance. This indicates that temperature-dependent gecko predatory impacts will be mediated by population demographics. We advocate further comparisons of functional responses to understand the invasiveness and future predatory impacts of geckos, and other invasive species globally, as temperatures change. [ABSTRACT FROM AUTHOR]

Freshwater crayfish are bioindicators of environmental pollution, often used for the assessment of heavy metal (HM) presence in the tissues, a time-consuming and expensive task. In this study, we propose the use of the vibrational spectroscopy to detect in a fast, non-destructive and sensitive way the presence of HM in the cephalothorax exoskeleton of the freshwater crayfish. Incorporation of HM into the cephalothorax exoskeleton was investigated under controlled laboratory conditions. In particular, the cephalothorax exoskeleton of five crayfish species (Astacus leptodactylus, Procambarus clarkii, Austropotamobius pallipes, Faxonius limosus, and Pacifastacus leniusculus) was analyzed by attenuated total reflection–Fourier transformed infrared (ATR–FTIR) spectroscopy in the presence or absence of cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni), and zinc (Zn) up to 4 weeks at various concentrations (0.01, 0.1, 1, 10, ppm). The ATR–FTIR profile of the crayfish cephalothorax exoskeleton was compatible with the presence of amorphous calcium carbonate, chitin, and proteins. The incubation with the HM revealed two main modifications: the shift of the peak from 859 to 872 cm−1 and the appearance of a peak at 712 cm−1. Both are ascribable to the HM interaction with calcium carbonate. The absorbance of both peaks increased along with the time of incubation, and the HM concentration. We conclude that ATR–FTIR analysis can be a useful, quick, and cost-sensitive tool to detect HM presence in the crayfish cephalothorax exoskeleton. However, it has to be regarded as a non-specific analytical technique for assessing HM contamination, since it is unable to discriminate between different HM. [ABSTRACT FROM AUTHOR]

[Display omitted] • The capital of Hungary is a hotspot of diversity of introduced ornamental crayfish. • We evaluated whether their release contributes to crayfish plague pathogen spread. • Four species were infected, including Procambarus virginalis, P. clarkii, P. alleni. • We observed unusual associations of Aphanomyces astaci genotypes and host crayfish. • Switch between dominant A. astaci genotypes occurred in one invaded site over time. Ornamental trade has become an important introduction pathway of non-native aquatic species worldwide. Correspondingly, there has been an alarming increase in the number of established crayfish of aquarium origin in Europe over the previous decade. The oomycete Aphanomyces astaci , the pathogen causing crayfish plague responsible for serious declines of European crayfish populations, is dispersed with introduced North American crayfish. The role of ornamental taxa in introducing and spreading different genotypes of this pathogen in open waters remains unclear. We investigated the distribution, prevalence, and diversity of A. astaci in Budapest, Hungary, which became a hotspot of aquarium crayfish introductions. Their establishment in this area was facilitated by locally abundant thermal waters. We screened for A. astaci in six host taxa from 18 sites sampled between 2018 and 2021: five cambarids (Cambarellus patzcuarensis , Faxonius limosus , Procambarus alleni , P. clarkii , P. virginalis) and one native astacid (Pontastacus leptodactylus). The pathogen was confirmed at five sampled sites in four host taxa: P. virginalis, P. clarkii, F. limosus , and for the first time in European open waters also in P. alleni. Genotyping was successful only in individuals from two different brooks where multiple host species coexisted but revealed unexpected patterns. Mitochondrial B-haplogroup of A. astaci , previously usually reported from Pacifastacus leniusculus or infected European species, was detected in P. virginalis at both sites, and in both F. limosus and P. virginalis sampled from a thermally stable tributary of Barát brook in 2018. In contrast, A-haplogroup of A. astaci was detected in coexisting F. limosus , P. virginalis and P. clarkii sampled in the same watercourse just a few hundred meters downstream in 2020. Additional genotyping methods indicated that a previously unknown A. astaci strain was associated with the latter haplogroup. One P. virginalis individual from 2020 was apparently co-infected by strains representing both mitochondrial haplogroups. The results indicated multiple sources of A. astaci in Budapest, likely directly associated with the introduction of ornamental species, interspecific transmission of this pathogen among ornamental hosts, and potential for a quick spatial or temporal turnover of dominant A. astaci strains at a certain locality. This highlights that in regions with high richness of potential A. astaci hosts, host taxon/pathogen genotype combinations become unpredictable, which might prevent reliable genotyping of pathogen sources in local crayfish mass mortalities. [ABSTRACT FROM AUTHOR]

• Diclofenac (DCF) was uptaken into crayfish hemolymph. • pH was negatively correlated to DCF hemolymph concentration. • DCF affected antioxidant and neurotoxicity enzyme activities. • pH influenced DCF toxicological effects in crayfish. • The highest DCF toxicological response was induced in crayfish gills. The widespread use and continuous discharge of pharmaceuticals to environmental waters can lead to potential toxicity to aquatic biota. Pharmaceuticals and their metabolites are often complex organic and environmentally persistent compounds that are bioactive at low doses. This study aimed to investigate the effects of diclofenac (DCF) on the antioxidant defence system and neurotoxicity biomarkers in signal crayfish (Pacifastacus leniusculus) under weakly acidic and basic conditions. Crayfish were exposed to 200 µg/L of DCF at pH 6 and 8 for 96 h and subsequently underwent the depuration phase for 96 h. Gills, hepatopancreas, and muscle were sampled after the exposure and depuration phases to assess the toxicological biomarker responses of DCF in crayfish by evaluating lipid peroxidation (LPO) levels, activities of antioxidant enzymes and acetylcholinesterase. After the exposure phase, the hemolymph DCF concentration was detected one order higher at pH 6 than at pH 8. The DCF was subsequently fully eliminated from the hemolymph during the depuration phase. Our results showed that DCF caused alteration in the activities of six of the seven tested biomarkers in at least one crayfish tissue. Although exposure to DCF caused imbalances in the detoxification system on multiple tissue levels, it was regenerated to a balanced state after the depuration phase. Integrated biomarker response (IBRv2) showed that the highest toxicological response to DCF exposure was elicited in the gills, whereas the hepatopancreas was the highest-responding tissue after the depuration phase. Exposure to DCF at pH 6 caused higher toxicological effects than at pH 8; however, crayfish antioxidant mechanisms recovered more quickly at pH 6 than at pH 8 after the depuration phase. Our results showed that water pH influenced the toxicological effects of DCF, an ionisable compound in crayfish. [Display omitted] [ABSTRACT FROM AUTHOR]

The red-rimmed melania Melanoides tuberculata (O. F. Müller) has been used in the aquarist trade and biocontrol programs, leading to its emergence outside its native range. Two populations of the red-rimmed melania occur in Slovakia. We investigated the morphometric features of mentioned populations and made a comparison. These two populations differ significantly in investigated features. Mean shell length of red-rimmed melania individuals from the Opatovce nad Nitrou was 14.7 mm, while the mean shell length of specimens from Piešťany was 24.4 mm (p < 10−6). Mean shell width, aperture length, and aperture width for specimens from the Opatovce nad Nitrou was 4.4 mm, 4.1 mm, and 2.3 mm, respectively. Mean shell width, aperture length, and aperture width of Piešťany specimens was 7.5 mm (p < 10−6), 7.1 mm (p < 10−6), and 3.8 mm (p < 10−6), respectively. The maximum shell length of specimens from the Opatovce nad Nitrou site was 22-23 mm, while shell length of specimens from Piešťany reached 32-33 mm. Regression analysis of the shell length and shell width, aperture length and aperture width, indicate equivalent relationship of the shell patterns for the two populations. Population structure analysis provided first inside of their population status, identifying a proliferating population at the Opatovce nad Nitrou site, while only adult individuals were observed at the site in Piešťany. The red-rimmed malania is a good candidate for possible biological invasions in thermal waters of temperate zone. [ABSTRACT FROM AUTHOR]

In 2017, a new non-indigenous crayfish species was found established in Europe. The captured individuals were identified as an orange morph of the Mexican dwarf crayfish Cambarellus patzcuarensis Villalobos, 1943. Fifteen adults (including three ovigerous females) and 26 juveniles were collected in a thermal pond in Budapest, Hungary. Two additional adults were caught below the pond's outflow in the adjacent Danube River. To our knowledge, this is the first record of a C. 'patzcuarensis population outside North America, which is also true for the rest of dwarf crayfish (family Cambaridae, subfamily Cambarellinae). With this finding, indigenous crayfish species in Europe are now more than two-fold outnumbered by non-indigenous species. An analysis of the probability of establishment of C. patzcuarensis in continental Europe revealed that specific regions in the south of the continent are suitable areas for the establishment of the species. Moreover, as a confirmed carrier of the crayfish plague pathogen, this species should be treated with caution and eradicated if possible. [ABSTRACT FROM AUTHOR]

Crayfish plague, caused by the oomycete Aphanomyces astaci and spread primarily by its original crayfish hosts from North America , not only threatens populations of endangered crayfish but also impacts their fisheries and aquaculture. This includes the narrow-clawed crayfish (Pontastacus leptodactylus) in Turkey, where its fishery and export used to grow until the mid-1980s when the accidental introduction of crayfish plague caused stock collapses. Although crayfish densities in some Turkish lakes returned to levels where fishery is feasible, persistent chronic infections by A. astaci prevent full crayfish population recovery and stock exploitation. The establishment of closed culturing systems faces the problem of substantial mortality of both broodstock and juveniles originating from the wild, apparently associated with the stress-induced development of crayfish plague symptoms. In our experiment, we evaluated whether A. astaci is vertically transmitted to juveniles during maternal incubation, and to what extent hatching of crayfish eggs in artificial conditions, coupled with antifungal baths, limits the infection by this pathogen. Egg-carrying (berried) crayfish females were caught from the Lake Eğirdir, Turkey, shortly before juvenile hatching. Eggs stripped from females were assigned into four experimental groups: two groups were treated with antifungal baths (formaldehyde or peracetic acid), the other two groups were controls kept without antifungal treatment but set up in conditions differing in the likelihood of accidental A. astaci transmission. Eggs on five berried females were kept for maternal incubation. The results confirmed that nearly all wild-caught females tested for the presence of A. astaci DNA by quantitative PCR were infected, and A. astaci infections were frequently confirmed in the maternally incubated juveniles. In contrast, we did not confirm unambiguous A. astaci infection in any juvenile from eggs treated by antifungal baths and from one of the control groups, which were all kept on a strictly separated flow-through system. However, juveniles from the control group on a recirculating system, in which also infected crayfish (e.g., maternal incubation group) were present, suffered elevated mortality, likely related to the accidental introduction of the pathogen that was confirmed in this treatment. The separation of the eggs from infected mothers before hatching apparently substantially reduces pathogen vertical transmission, and combination with an antifungal treatment further increases juvenile survival. Although it cannot be guaranteed that the juveniles that hatched and developed in artificial conditions are entirely A. astaci- free, the approach seems suitable for routine aquaculture applications in regions where chronic infections by this pathogen are widespread. • Chronic infection by the crayfish plague pathogen may impair aquaculture production. • Eliminating pathogen transmission to crayfish juveniles may help culture set-ups. • Maternally incubated juveniles get infected from mothers and/or environment. • Stripping of eggs from females before hatching may limit the vertical transmission. • Further guidelines to exclude pathogen from chronically infected stock are provided. [ABSTRACT FROM AUTHOR]

The marbled craynsn ( Procambarus fallax f. virginalis) has become one of the potentially most dangerous nonindigenous crayfish species spreading in European countries and elsewhere. This taxon reproduces parthenogenetically and recently has been verified as a vector of the crayfish plague pathogen. Here, we report on two established populations of marbled crayfish in the Czech Republic. The marbled crayfish was observed during autumn 2015 in an urban pond connected by sewer piping with the Rokytka brook near its mouth to the Vltava River in Prague. Subsequently, three adult females, two of them having well-developed glair glands and oocytes, were captured in this pond during spring 2016, suggesting successful overwintering of the local population. Furthermore, four adult females were captured in an artificial pond at the Radovesická lignite spoil heap in the vicinity to the industrial conurbation of Bílina in summer 2016; one of them carried eggs. We tested these for the presence of the crayfish plague pathogen Aphanomyces astaci, with negative results. The introduction pathway for both populations is most likely a release from private aquaria, as these sites are popular for recreation activities. Our findings substantiate previous predictions that conurbations are likely to be the primary areas for marbled crayfish introductions. [ABSTRACT FROM AUTHOR]

Diphenhydramine (DPH) is a pharmaceutical with multiple modes of action, primarily designed as an antihistamine therapeutic drug. Among antihistamines, DPH is a significant contaminant in the environment, frequently detected in surface waters, sediments, and tissues of aquatic biota. In the present study, signal crayfish Pacifastacus leniusculus was used as a model organism because of their prominent ecological roles in freshwater ecosystems. The biochemical effects were investigated in crayfish exposed to the environmental (low: 2 μg L−1), ten times elevated (medium: 20 μg L−1), and the sublethal (high: 200 μg L−1) nominal concentrations of DPH in water for 96 h. Lipid peroxidation, antioxidant enzyme activities, and acetylcholinesterase activity were assessed as toxicological biomarkers in crayfish hepatopancreas, gills, and muscles. Low and medium DPH exposure caused imbalances only in glutathione-like enzyme activities. Integrated biomarker response showed the absolute DPH toxicity effects on all tested tissues under high exposure. This study identified that high, short-term DPH exposure induced oxidative stress in crayfish on multiple tissue levels, with the most considerable extent in muscles. [Display omitted] • Diphenhydramine (DPH) was uptaken into crayfish hemolymph. • The DPH concentration 200 μg L−1 induced the highest toxicity biomarker response. • The highest oxidative stress was induced in muscles. • DPH did not influence acetylcholinesterase activity in tested tissues. [ABSTRACT FROM AUTHOR]

After mating, spermatophores of signal crayfish are stored on the body of the female for a period before fertilization. This study compared the post-mating protein profile and pattern of protein tyrosine phosphorylation of the signal crayfish spermatophore to that of the freshly ejaculated spermatophore and found substantial differences. Two major bands of tyrosine-phosphorylated proteins of molecular weights 10 and 50 kDa were observed in the freshly ejaculated spermatophore of the signal crayfish. While the tyrosine-phosphorylated protein band with molecular weight 10 kDa was formed by protein(s) of similar pH, the band with molecular weight of 50 kDa consisted of proteins of varying pH. In the post-mating spermatophore, the band with molecular weight of 50 kDa was not detected, and an increase in the level of protein tyrosine phosphorylation was observed in the 10 kDa band. The microtubular radial arms of the spermatozoon showed a positive reaction to an anti-tyrosine antibody conjugated with gold particles in both the freshly ejaculated and post-mating spermatophores. In conclusion, the male gamete of the signal crayfish undergoes molecular modification during post-mating storage on the body of the female including changes in the level of protein expression and protein tyrosine phosphorylation. Structural similarity of the radial arms in the crayfish immotile spermatozoon with flagellum, which is the main site of protein tyrosine phosphorylation in the mammalian motile spermatozoa, raises questions regarding evolution and function of such organelles across the animal kingdom that must be addressed in the future studies. [ABSTRACT FROM AUTHOR]

Crayfish spermatophores are deposited on the body surface of the female during mating and remain there for a period of time before fertilization ensues. Post-mating changes in protein expression level in the noble crayfish Astacus astacus spermatophore were quantified. In-gel digestion and high resolution mass spectrometry were used for label-free protein quantification. One hundred twelve proteins were identified in the spermatophore of noble crayfish. After 7 days of storage on the body of the female, 6 proteins were identified in the post-mating spermatophore that showed significant up-regulation and 4 significant down-regulations ( p < 0.05, fold change ≥ 2). The highest rate of up-regulation was observed in sodium/hydrogen exchanger, which may indicate the importance of intracellular pH adjustment for final maturation of the crayfish spermatozoon. The highest rate of down-regulation was observed in histone H2A. This may increase chromatin flexibility and facilitate its transfer into the oocyte during fertilization. The vitellogenin protein was identified in the crayfish spermatophore and its level changed during storage on the body surface of female. Extensive proteomic modification of male gametes during storage on the body surface of the female suggests post-mating final maturation of the crayfish spermatozoon. Biological significance Freshwater crayfish comprise a large and diverse group of ecologically and commercially important animals. Molecular studies of gametes in the crayfish can provide insight into the complex process of reproduction in this diverse group of animals. The results of such studies can be used for development of new techniques for artificial reproduction of these economically important species. [ABSTRACT FROM AUTHOR]