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The pet trade is one of the most important sources of introduction of freshwater non-native decapod crustaceans. Precise and timely identification of potentially hazardous species is necessary for the effective prevention of new introductions. Here, we present a list of species of ornamental freshwater decapod crustaceans pet-traded in Hungary and their risk assessment, including the probability of establishment based on climate matching. The list contains 13 shrimps, eight crayfish, two crabs, and one hermit crab. Three crayfish, Cherax destructor, Procambarus clarkii, P. virginalis, and one crab, Eriocheir sinensis, were classified in the high-risk category. During field sampling, we found three individuals of C. quadricarinatus that were probably released or escaped from aquaria. These are the first records of this species in the wild of Carpathian Basin. We strongly recommend further educating hobbyists about the risks related to the escapes and releases of high-risk taxa, as well as monitoring of the region for their occurrence. [ABSTRACT FROM AUTHOR]

Species' introductions may cause severe adverse effects on freshwater ecosystems and their biota. The marbled crayfish, Procambarus virginalis Lyko, 2017, is an invasive parthenogenetically reproducing crayfish with rapid reproduction, maturation and tolerance to a wide range of environmental conditions, which was introduced to many sites across Europe during the last decade. Due to its recent speciation and limited number of field studies, the knowledge of trophic interactions of the marbled crayfish in freshwater food webs is scarce. An invaded area located in Central Europe was studied to identify the marbled crayfish food web interactions using analysis of carbon 13C and nitrogen 15N isotopes. This study brings the first insight into the trophic ecology of marbled crayfish in lentic freshwater ecosystems. Algae and detritus were identified as the most important food sources for the marbled crayfish, while zoobenthos and macrophytes were less important. Moreover, the marbled crayfish was found to be an important food source for top fish predators, but marginal for omnivorous fish. Being able to utilize energy from the bottom of the trophic food web, the marbled crayfish may have important roles in the ecosystem, transferring energy to higher trophic levels. It processes allochthonous and autochthonous matter in the ecosystem, thus being a competitor to other organisms with similar food preferences and impacting zoobenthos, algae and macrophytes through predation or direct consumption. To sum up, the marbled crayfish has a strong ability to utilize food sources from different trophic levels, and, thanks to its life history, can be a highly adaptable invader. [ABSTRACT FROM AUTHOR]

Numerous freshwater crayfish species are known to become successful invaders when introduced to new territories. One of the most invasive species in this group is the red swamp crayfish, Procambarus clarkii (Girard, 1852). In addition to other characteristics facilitating its invasiveness, it is also a vector of crayfish plague, a disease mostly lethal to crayfish of non‐North American origin.Procambarus clarkii, at present the most widespread crayfish species globally, is popular in many countries both for human consumption and as an ornamental animal. An established population of this species was documented for the first time within Indonesia, representing the first record for maritime Southeast Asia. The species is also common in the local ornamental pet trade.Infection by the crayfish plague pathogen Aphanomyces astaci Schikora was confirmed both in the outdoor population of P. clarkii and in one of the surveyed pet shops. Furthermore, A. astaci was detected in specimens of freshwater crab and shrimp species coexisting with P. clarkii.Local climatic conditions and the species temperature requirements suggest a high probability of the establishment of P. clarkii in Indonesia. Its further spread could irreversibly damage populations of many native endemic crustaceans in the country (as well as elsewhere in the region), and the thriving local aquacultures of the redclaw crayfish Cherax quadricarinatus (von Martens, 1868) may also be threatened.The total ban of P. clarkii and other crayfish species of North American origin in Indonesia is strongly recommended, especially considering that aquaculture and trade with Australasian species is a viable alternative option. [ABSTRACT FROM AUTHOR]

The redclaw crayfish, Cherax quadricarinatus, is a freshwater crayfish native to north-eastern Australia and southern New Guinea. In 2016, the species was found for the first time west of the Wallace Line in Java, Indonesia and, based on climate matching, its further spread within Indonesian territory was predicted. In this study, surveys of selected localities within Indonesia were performed to examine the species occurrence. Redclaw crayfish were found throughout Indonesia, in numerous rivers, lakes, ponds and reservoirs in Batam and Bintan Islands (Riau Archipelago), Java, Kalimantan (Borneo), Sulawesi and Sumatra. Some stocks were apparently well established, providing a food source for local people and sustaining capture for pet trade purposes. Because there are no effective regulations of introductions and exploitation of this crayfish in Indonesia, its further spread to new localities is expected. Increased attention to this issue, especially regarding crayfish management and policy implementation, is urgently needed. [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 this study, cardiac and locomotor activities of signal crayfish Pacifastacus leniusculus were investigated under exposure to a range of natural (i.e., odors of conspecific crayfish, predatory fish, food, and injured conspecific) and one chemical (i.e., disinfectant chloramine-T) stimuli. Crayfish locomotion was simultaneously initiated with an increase in heart rate only when affected by chloramine-T, while locomotor response was delayed in all cases (or was not manifested at all by some specimens) when disturbed by the natural stressors. The heart rate differences measured before and during the stimulation were arranged as follows: odor of conspecific crayfish (9.2 ± 7.1%) < predator (18.4 ± 13%) < food (33.5 ± 15.7%) < chloramine-T (41.1 ± 14.7%) < injured conspecific (51.8 ± 28.4%). Analysis of the peculiarities of crayfish heartbeat under exposure to the tested stimuli revealed complex cardiac responses as was previously observed by an electrocardiography approach, that is, a slowed heart rate followed by a delayed increase. Evaluation of the intrinsic parameters of crayfish bioindicators remains essential due to the possibility of detection of the substantial ethological responses even in motionless animals. The role and appropriateness of signal crayfish as a bioindicator of water quality is discussed; they seem to be an applicable species for this task due to their sufficient sensitivity and broad availability. In addition to providing a better understanding of stereotypic crayfish behaviors induced by common and chemical stressors, the results of this study may serve as reference data for the evaluation of crayfish suitability for water quality tests. [ABSTRACT FROM AUTHOR]

Invasive alien species present a global threat to biodiversity, particularly where pathogens and symbionts are involved. Nonnative crayfish species can increase their impact on the host ecosystem through introductions of symbiotic fauna. Conversely, nonnative crayfishes could serve as hosts for native epibionts, thus substituting for disappearing native crayfishes as well. Here we report the presence of native branchiobdellids on naturalized populations of non-native crayfish Orconectes limosus and Pacifastacus leniusculus living in sympatry with native Astacus astacus. The native crayfish species probably served as a source of Branchiobdella spp. for non-native crayfishes. Two species of Branchiobdella (B. parasita and B. pentadonta) were found on P. leniusculus while only B. parasita was found on O. limosus. The level of colonization of inspected specimens and species was also evaluated. The mean number of branchiobdellids found on P. leniusculus and O. limosus was 26.0±15.9, and 64.8±27.7, respectively. Orconectes limosus was more heavily colonized by Branchiobdella despite being significantly smaller than P. leniusculus. Non-native species were corroborated as suitable to host the native epibionts. [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]

The pet trade has been responsible for many introductions of non-native species. Freshwater ornamental plants and animals originating from the pet trade are stocked to garden ponds. The present survey focused on awareness and responsible behaviour related to biological invasion risks of companies that designed, built, and stocked garden ponds., A representative number ( n = 124) of companies (commercial garden pond architects and builders) in the Czech Republic were surveyed regarding the offer of non-native, invasive and threatened native species. The survey was conducted over the entire warm period (from 1 May 2015 to 31 September 2015) while using personal visits, correspondence and interviews to list the species on offer., 'Traditional' ornamental species were offered by 39.1% of surveyed vendors, non-traditional 'marginal' species by 5.6%, common native species by 6.5% and threatened native species by 2.4%., The findings of this study support the hypothesis that 'garden pond' vendors offer non-native species with a risk of biological invasion; moreover, threatened native animals were also on sale. It is probable that a similar situation exists in other countries. It is important for the conservation of native aquatic biota to raise awareness of the need to reduce risk through responsible behaviour of those involved in the pet trade. It is also essential to prohibit stocking of potential invaders and to enforce the illegal capture and sale of native species. [ABSTRACT FROM AUTHOR]

Cherax (Cherax) subterigneus n. sp., is a crayfish endemic to the Aitinjo Lake of West Papua, Indonesia. This species is one of the field-captured species from this region that are exploited for ornamental purposes. Its commonly used commercial name in the pet trade is "Black Orange Tip Crayfish," "Orange Tip Crayfish," or "Red Tip Crayfish." The new species is genetically and morphologically similar to Cherax holthuisi, however, both species can be easily distinguished by certain morphological characteristics or by using sequence divergence, which is substantial, for considering C. subterigneus n. sp. as a valid species. We have also added a note about the probable incorrect subgeneric assignment of the Cherax peknyi and mandatory change of incorrect original spelling of recently described C. gherardii as C. gherardiae. [ABSTRACT FROM AUTHOR]

Development of artificial crayfish egg incubation is a milestone in intensive culture of crayfish as commercially important freshwater animals. This study evaluated experimental treatments combining continuous UV lighting, a non-chemical antifungal treatment, with an initial formaldehyde bath for noble crayfish ( Astacus astacus) eggs incubated in semi-recirculating systems, which requires less than 1 per cent the amount of water necessary for conventional flow-through systems. The one-time administration of a pre-incubation bath to reduce formaldehyde exposure was ineffective. Ultraviolet irradiation of recirculating water provided poor results (13.5% and 35.2% final survival rates to stage 2 juveniles) and led to deteriorating water quality. An inability of hatchlings to successfully moult and the occurrence of limb deformities was observed in UV-treated groups, and juvenile mortality was found across all experimental treatments. [ABSTRACT FROM AUTHOR]

Biological invasions are impacting biota worldwide, and explaining why some taxa tend to become invasive is of major scientific interest. North American crayfish species, particularly of the family Cambaridae, are prominent invaders in freshwaters, defying the ''tens rule'' which states that only a minority of species introduced to new regions become established, and only a minority of those become invasive and pests. So far, success of cambarid invaders has largely been attributed to rapid maturation, high reproductive output, aggressiveness, and tolerance to pollution. We provide experimental evidence that females of one cambarid species particularly widespread in Europe, the spiny-cheek crayfish Orconectes limosus, are capable of facultative parthenogenesis. Such reproductive mode has never before been recognized in decapods, the most diverse crustacean order. As shown by analysis of seven microsatellite loci, crayfish females kept physically separated from males produced genetically homogeneous offspring identical with maternal individuals; this suggests they reproduced by apomixis, unlike those females which mated with males and had a diverse offspring. Further research is needed to clarify what environmental conditions are necessary for a switch to parthenogenesis in O. limosus, and what role it plays in natural crayfish populations. However, if such reproductive plasticity is present in other cambarid crayfish species, it may contribute to the overwhelming invasive success of this group. [ABSTRACT FROM AUTHOR]

The article presents a study that deals with morphological changes associated with form alternations in the male spiny-cheek crayfish Orconectes limosus. Included in the study were male species which were observed from February to November 2008. Observations revealed two moltings experienced by 84.4 percent of most males while 8.9 percent only molted once without a form of alteration. Water temperatures of 16°Celsius triggered molting, according to the authors. They described form I gonopods as longer, wider, and more robust compared with form II gonopods. They highlighted the functionality of form alternation after allowing the utilization of resources which led to increased size of males.

The decline of native crayfish biodiversity caused by introductions of invasive crayfish has been well documented; however, the fate of their associated biota remains overlooked. Native European branchiobdellids (Annelida: Clitellata)—crayfish ectosymbionts—were monitored in Czech Republic in three localities with past or present sympatric occurrence of the native noble crayfish Astacus astacus (AA) and invasive signal crayfish Pacifastacus leniusculus (PL). No branchiobdellids were detected in two localities with abundant populations of PL but with absences of AA, although they were recently recorded there. Two species of branchiobdellids (Branchiobdella parasita and B. pentadonta) were detected on both crayfish species in the locality where AA still coexists with PL. However, PL harboured a significantly lower abundance of both branchiobdellids than AA (80.7% and 90.8% decrease, respectively) and a significantly lower number of their attached cocoons (95.7% and 95.0% decrease, respectively). Nevertheless, the abundance of branchiobdellids was positively correlated with the carapace length in both crayfish species. Other potential predictors related to crayfish biological parameters (e.g. sex or missing appendages) were not significantly related to the abundances of both branchiobdellids and their cocoons. We also performed laboratory experiments with both branchiobdellids distributed on size-matched individuals of AA and PL to verify the results of field observations. The probability for branchiobdellid survival was significantly higher on AA in both branchiodellids for all the time of the experiments. The absence or decreased abundances of the native branchiobdellids in the invasive crayfish suggest their limited capability to deal with the replacement of host species. [ABSTRACT FROM AUTHOR]