|
|
Monitoring reakce raků na různé podněty: jsou raci dobrými bioindikátory?
MALINOVSKA, Viktoriia
Freshwater crayfish play a vital role in food webs and energy transfer between trophic levels, often acting as keystone species. Crayfish are prime species among invertebrates, considering their large size, abundance, and biodiversity. Crayfish belong to common model organisms in scientific research and have been used as bioindicators of water quality in laboratory and field studies. Freshwater crayfish are at direct risk while facing polluted aquatic environments, as many chemicals enter natural waters throughout the year. Studies have been shown that crayfish exhibit a variety of behavioral and physiological alterations in response to anthropogenic contaminants. In Chapter 2, we aimed to assess the cardiac and locomotor responses of crayfish Pacifastacus leniusculus to short-term pulse exposure to environmentally relevant concentrations of three pesticides (metazachlor, terbuthylazine, and thiacloprid). A significant increase in heart rate and distance moved was observed in metazachlor-exposed specimens compared to controls. We did not detect significant changes in crayfish cardiac and locomotor activity in terbuthylazine and thiacloprid groups. Most crayfish in these groups did not exhibit locomotor response, so they might not be stimulated to escape a contaminated area. This may lead to continuous exposure to environmental chemicals that are potentially harmful. In Chapter 3, we investigated the effects of UV filters Benzoyl-4-hydroxy-2-methoxybenzenesulfonic acid (BP4) and 2-Phenylbenzimidazole-5-sulfonic acid (PBSA) on crayfish during 30 min exposure period. Specimens exposed to the tested compounds moved greater distances and spent more time in locomotion. Increased heart rate was also detected in treated groups. Such behavioral and physiological alterations of crayfish detected in both studies can potentially impair crayfish ability to respond to predators, and consequently affect abundance and the functional properties of macroinvertebrate communities. Along with use of crayfish in laboratory and field experiments, there is also an option to conduct case study with crayfish acting as bioindicators. We evaluated crayfish physiological responses to water disinfected with chlorine dioxide in long-term monitoring under operating conditions in local brewery (Chapter 4). The disruption of cardiac rhythmicity was detected with chaotic increases and decreases of heart rate regardless of the time of day. In natural environment, heart rate of crayfish is higher during night time considering nocturnal activity of these decapods. Nocturnalism is important adaptation for crayfish, and its impairment can lead to certain risks related to increased visibility to predators and alterations in foraging. Our results indicated that crayfish exhibit a cardiac and locomotor responses when shortly exposed to commonly used herbicide metazachlor and two widely applied UV filters BP4 and PBSA, suggesting that crayfish can potentially detect the appearance of these aquatic contaminants in water. The usefulness of crayfish in long-term monitoring of water quality have also been demonstrated. These findings expand our understanding of using crayfish as bioindicators in scientific research. In conclusion, this thesis provides the data from laboratory and case studies focusing on measurements of cardiac and locomotor endpoints in crayfish. Given that crayfish is at the base of the food chain in freshwater environments, it is of great importance to study the effects of different stimuli on such keystone species. Understanding further biological impacts of aquatic pollutants on freshwater crayfish and other non-target taxa will benefit our knowledge of threats to functional compositional changes in populations and communities.
|
|
|
Vliv hygienicky ošetřené vody na srdeční frekvenci raka a jejich následnou mortalitu
MALINOVSKA, Viktoriia
The study is focused on the evaluation of crayfish physiological reaction on hygienically treated water with chlorine dioxide (ClO2). A patented non-invasive monitoring system was used for observation of crayfish cardiac and locomotor activity. Monitoring was conducted from February to August 2017 under conditions of private commercial enterprise "Pivovar Protivín" in Czech Republic. Adult individuals of signal crayfish, Pacifastacus leniusculus, were kept separately in water-flow aquariums directly after the water treatment device producing ClO2 in concentration from 0.01 to 0.29 mg.l-1. Observed crayfish response to the disinfectant varied among individuals which could be explained by a different functional state and individual reaction on stimuli. Diurnal rhythm of some crayfish was disturbed even at a lower concentrations of chlorine dioxide (0.01-0.2 mg.l-1), while higher concentrations affected all animals. In addition to that, higher levels of chlorine dioxide ( 0.2 mg.l-1) significantly increased mortality. Maximum concentrations (0.2-0.29 mg.l-1) were observed 28 times in total during 202 days of monitoring, which resulted in 25 mortality cases occurred several days after exposure. In average, mortality of crayfish occurred three-four weeks after stocking to the experimental system. Possible lethal concentration of ClO2, which caused animal mortality, is 0.2 mg.l-1. Results suggested that crayfish exposure to ClO2, obviously, negatively affect their physiological processes; however, further studies are needed to examine specific effects of chlorine dioxide on internal organs of crayfish.
|
guest ::
