Využití raků jako bioindikátorů kvality vody

In recent decades, the ecological status of the freshwater crayfish has changed drastically from a sensitive indicator of an aquatic environment to a tolerant species that can survive in a wide range of unfavourable conditions. Despite all controversies on being or not being proper bioindicators, crayfish are a key species that plays a crucial role in the freshwater ecosystem. Regardless of whether certain crayfish possess a particular environmental sensitivity or not, all species can be used in biomonitoring investigations. The main objectives of the present thesis were development and implementation of system for continuous monitoring of water quality using crayfish as the bioindicator. Being less complex than vertebrates (e.g., fish), but being sufficiently complex compared to some other hard-shell freshwater invertebrates (e.g., mussels), crayfish present a useful biomonitoring object, which is easy to manipulate with, and which provides experimental data which is easy to obtain, analyse and interpret. The first part of this thesis is devoted to an evaluation of crayfish as suitable bioindicators. We showed that, when conducting the biomonitoring of metals in aquatic biota, crayfish have sufficient tissues for a bioaccumulation survey. For this purpose, we examined the gills, muscles and hepatopancreas. We confirmed that the hepatopancreas was the primary target for accumulation of most of the examined elements (i.e., cadmium, chromium, copper, nickel, zinc). For higher relevance, crayfish surveys were compared to fish samples collected from the same locations. The second part of this work particularly focused on water quality biomonitoring based on the evaluation of crayfish ethophysiological characteristics. We examined crayfish reactions to both chemical (i.e. chloramine, chlorides, nitrites) and natural odours (i.e., food, heterosexual conspecifics, predator, etc). This approach was shown to be simple yet at the same time, complex and efficient. Such monitoring technique is easily implemented and does not demand long, complicated analyses, since monitored parameters, locomotor and cardiac activity, are evaluated immediately in real time. However, one complication is related to the unpredictability of an animal's reactions. Because studied characteristics may often affect each other, they need to be carefully traced and interaction between measured characteristics needs to be eliminated. The usefulness of such biomonitoring is conditioned by a reliable combination of behaviour and physiology, which enables detection of complex animal responses to environmental changes. As reported in the third part, we submitted an application for a patent of the developed system, and described in the patent sensor will be protected as utility model. Moreover, other crustaceans with sufficient carapace size (e.g., shrimps, crabs, molluscs) can be successfully investigated using presented system. The only challenge is that living organism can clearly indicate disruption of ambient conditions, but cannot detect what it has caused. However, there are powerful analytical techniques now, developed exactly for accurate determination of various compounds. The heart rate is species- and conditions-specific, so it cannot be applied as unified measure for all crayfish species, while visual analysis of heartbeat primary curves can be useful for establishment of referent crayfish heart rate values at their different functional states. The final part of the thesis is devoted to this issue. In conclusion, the developed biomonitoring system was shown to be highly practical unit using noninvasive technique for investigation of crayfish reactions under model conditions, with the potential of further application at broader research and industrial arenas

Short-term effects of an environmentally relevant concentration of organic UV filters on signal crayfish Pacifastacus leniusculus

Personal care products, including organic UV filters, are considered emerging contaminants, with their toxic effects being a concern in recent decades. UV filters continually enter surface waters via wastewater and human activity. Despite the presence of organic UV filters in the freshwater environment, little is known of their impact on aquatic biota. In this study, we evaluated the cardiac and locomotor responses of signal crayfish Pacifastacus leniusculus exposed to environmentally relevant concentrations of either 2-Phenylbenzimidazole-5-sulfonic acid (PBSA, 3 µg/L) or 5-Benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid (BP4, 2.5 µg/L). Specimens exposed to the tested compounds for 30 min exhibited significantly greater changes in distance moved and time active than did unexposed controls. Significant differences of mean heart rate change compared to control were detected in both PBSA and BP4 experimental groups. Such behavior and physiological alterations demonstrate ecological effects of personal care products with the tested sunscreen compounds even with a short exposure. Evidence of the consequences of organic UV filters on aquatic organisms is scarce and is an important topic for future research

Crayfish as Bioindicators for Monitoring ClO2: A Case Study from a Brewery Water Treatment Facility

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

Accumulation of Heavy Metals in Crayfish and Fish from Selected Czech Reservoirs

To evaluate the accumulation of aluminium, cadmium, chromium, copper, lead, mercury, nickel, and zinc in crayfish and fish organ tissues, specimens from three drinking water reservoirs (Boskovice, Landštejn, and Nová Říše) and one contaminated site (Darkovské moře) in the Czech Republic were examined. Crayfish hepatopancreas was confirmed to be the primary accumulating site for the majority of metals (Cu > Zn > Ni > Cd > Cr), while Hg and Cr were concentrated in abdominal muscle, and Al and Pb were concentrated in gill. Metals found in Nová Říše specimens included Cu > Zn > Ni and those found in Boskovice included Zn > Hg > Cr. Cd concentrations were observed only in Landštejn specimens, while contaminated Darkovské moře specimens showed the highest levels of accumulation (Cu > Al > Zn > Pb). The majority of evaluated metals were found in higher concentrations in crayfish: Cu > Al > Zn > Ni > Cr > Cd > Pb, with Hg being the only metal accumulating higher in fish. Due to accumulation similarities of Al in crayfish and fish gill, differences of Hg in muscle, and features noted for the remaining metals in examined tissues, biomonitoring should incorporate both crayfish and fish to produce more relevant water quality surveys

Cardiac and Locomotor Responses to Acute Stress in Signal Crayfish Pacifastacus leniusculus Exposed to Methamphetamine at an Environmentally Relevant Concentration

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

Effect of psychoactive substances on cardiac and locomotory activity of juvenile marbled crayfish Procambarus virginalis

Pharmaceutically active compounds are common and increasing in the aquatic environment. Evidence suggests they have adverse effects on non-target organisms, and they are classified as emerging pollutants for a variety of aquatic organisms. To determine the effects of environmentally relevant levels of psychoactive compounds on non-target organisms, we analyzed cardiac and locomotory activity in early developmental stages of marbled crayfish Procambarus virginalis. Responses to sertraline, methamphetamine, and a mixture of citalopram, oxazepam, sertraline, tramadol, venlafaxine, and methamphetamine at a concentration of 1 µg L-1 of each compound were assessed. On day four of exposure, cardiac activity was recorded for 5 min, and on day eight, locomotory activity was recorded for 15 min. There was a significant increase (p  0.05) in exposed and control animals. These findings revealed that low concentrations of chemicals and their mixtures can modify the physiological state of aquatic animals without outward manifestations (activity, distance moved, and velocity). Aquatic animals can be impacted earlier than is visible, but effects can potentially lead to substantial changes in populations and in ecosystem processes. Additional research to investigate chemical combinations, exposure systems, and organism physiological and molecular responses may provide evidence of broad impact of environmental pharmaceuticals