POSTER 7

The stone crayfish in the czech republic: lost-and-found in last seven years

Vlach P, Fischer D and Svobodová J

Within the period 2012-2015, an intensive research concerning: 1. mapping the occurrence of stone crayfish; 2. monitoring of presently known populations; 3. an evaluation of ecological demands of this species, was carried out. This contribution focuses on newly described localities, losses of some populations, and populations affected by a dramatic decrease in population densities in some localities. Moreover, the contribution introduces a hypothesis or/and particular reasons for that decrease or extinction. The extinction in Úpor brook and Hýskovský brook has already been published; recently we have recorded the following losses: Zákolanský brook, Bertínský brook, Vlcí brook, Kornatický brook, Hrádecký brook, and Medvedí brook. Whereas the combination of crayfish plague and (probably) low water quality caused the total mortality in lower part of the Zákolanský brook, crayfish plague outbreak killed crayfish in Kornatický and Hrádecký brook in 2015. Conversely, there was a lethal concentration of BOD5 in Vlcí brook. Also dramatic droughts in 2015 influenced the population densities in Chocenický and Prešínský brook. The mass mortality in Klabava was caused by a combination of stream acidification and toxic metal accumulation. The reasons for other losses are mostly speculative. On the other hand, within the mapping campaign, we found more than 10 new populations of stone crayfish. Nevertheless, the newly recorded occurrences correspond with a present range of this species in the Czech Republic.

POSTER 10

The Impact of Streetlights on an Aquatic Invasive Species: Artificial Light at Night Alters Signal Crayfish Behaviour

Thomas JR, James J, Newman RC, Riley WD, Griffiths SW and Cable J

Artificial light at night (ALAN) can alter the behaviour, communication and orientation of animals, and could interact with other stressors to affect biodiversity. Invasive, non-native species are one of the largest threats to freshwater biodiversity; however, the impact of ALAN on such species is unknown. This study assessed the effects of ALAN at ecologically relevant levels on the behaviour of a globally widespread invasive species, the signal crayfish (Pacifastacus leniusculus). Crayfish were exposed to periods of daylight, control (<0.1 lx) and street-lit nights to test two hypotheses: (1) signal crayfish under natural conditions are nocturnal animals and (2) ALAN reduces the duration of crayfish activity and intraspecific interactions, whilst increasing their propensity to use shelter. Our results confirm that signal crayfish are largely nocturnal, showing peak activity and interaction levels during control nights, whilst taking refuge during daylight hours. However, when exposed to ecologically relevant simulated light pollution from a streetlight at night, activity and interactions with conspecifics were significantly reduced, whilst time spent sheltering increased. Global anthropogenic changes such as ALAN may alter the life history traits and behaviour of invasive species and ultimately influence their impact on invaded ecosystems. The results of the present study suggest that ALAN could reduce the success of signal crayfish in urban areas, by drastically reducing their nocturnal activity. This study is the first to show an impact of ALAN on the behaviour of an invasive, non-native species, and provides information for the management of invasive crayfish in areas where ALAN is prevalent.

POSTER 11

Life History and Population Ecology of Signal Crayfish, the New Invader in Northern Italy

Ghia D, Fea G, Gruppuso L, Bo T, Candiotto A, Fenoglio S and Sacchi R

The occurrence of the signal crayfish Pacifastacus leniusculus in the Valla stream, north-western Italy, was one of the first reports of this invasive alien species in Italy. Since 2009 signal crayfish was spreading upstream from the artificial lake formed by a dam for hydroelectric purpose. We studied the signal crayfish population in this novel environment by trapping sessions during a year. Five sampling sites were located along the invaded range of the Valla stream, along more than 10 km. At each site, six baited traps were set once a month for two days, from April 2015 to March 2016. All signal crayfish were removed from the watercourse. Crayfish were sexed, weighted and the following morphometric parameters were measured: total length (TL), and cephalothorax length (CL). We trapped overall 433 females (mean TL: 84.7 mm) and 428 males (mean TL: 85.5 mm). Crayfish activity was correlated with water temperature. Egg-bearing females occurred from early November and hatching in late May. Sex ratio was about 1:1 in all sites except the most downstream one, where females were more abundant; and more females were caught during summer months. Crayfish TL and condition factor fluctuated during the year, but both decreased significantly moving upstream. Management actions should be promoted to limit its spreading overall within watercourses potentially suitable.

POSTER 22

Positive Selection of Beautiful Invasives: Long-term Persistence and Bio-invasion Risk of Ornamental Crayfish

Chucholl C and Wendler F

Following a distinct peak interest to keep freshwater crayfish in home aquaria in the mid-2000s, the aquarium trade has become a novel introduction pathway for alien crayfish species in Central Europe. Here, we provide an update on the German ornamental crayfish trade approximately one decade after the `crayfish hype´ to explore the long-term implications in terms of bio-invasion risk. Specifically, species’ availability and potential invasiveness, as well as the determinants of availability were assessed. In July 2015, a total of 31 online shops offered 28 crayfish species, which represents a decline of 24% in species diversity compared to the late 2000s. In addition, the estimated rate of import of new species has considerably flattened and approaches pre-hype values (< 1 species · y^-1). However, the risk associated with the offered species, as assessed by a risk screening tool (FI-ISK), has not decreased compared to the late 2000s. Long-term availability in the trade (covering one decade) was primarily determined by bright coloration, the ability to reproduce under warm aquarium conditions, and a preference for lentic habitats. Species featuring such traits are likely to persist in the aquarium trade and include four high-risk species, most notably invasive and crayfish plague-carrying red swamp crayfish (Procambarus clarkii) and Marmorkrebs (Procambarus fallax f. virginalis). Persistent propagule pressure from aquaria has substantially contributed to the establishment of both species in Central Europe, stressing the need for effective pathway management.

POSTER 24

Effect of Pharmaceuticals on Crayfish

Shaliutina O and Bláha M

The release of human pharmaceuticals and personal care products into aquatic ecosystems continues to be a serious environmental problem. There is a staggering list of pharmaceuticals that have been detected in surface water, groundwater and tap water. These compounds typically modify the physiology or behavior, of the intended target system, without lethal effect. The wide range of entry points into freshwater systems reaffirms that animals living within those habitats face continuous exposure to pharmaceuticals, even if only at low doses. Crayfish are a crucial invertebrate in freshwater ecosystems. They are omnivorous, and occupy a key position in the trophic web as both predator and prey. With the importance of crayfish to their ecosystems, the introduction of pollutants such as pharmaceuticals, could have negative effects to crayfish populations. For example, pharmaceuticals can cause a mediating aggressive behavior. It has been demonstrated that crayfish injected with serotonin (antidepressant) fights lasted considerably longer. Also, the lasting impact of pharmaceuticals leads to immune system function decline, which greatly increases the mortality rate. Moreover, they can slow down synthesize and release of hormones from the X-organ sinus complex, and thus influence molting, gonad development, water balance, blood glucose, etc. However, despite all data the impact of pharmaceuticals on particular developmental stages, mortality, growth rate and postembryonic development of crayfish had not yet been fully explored. Therefore, we provide an overview about the known effects of pharmaceuticals on crayfish and demonstrate that these effects could be quite multifaceted.