Radovan Kopp

MICROCYSTIN KINETICS (BIOACCUMULATION AND ELIMINATION) AND BIOCHEMICAL RESPONSES IN COMMON CARP (CYPRINUS CARPIO) AND SILVER CARP (HYPOPHTHALMICHTHYS MOLITRIX) EXPOSED TO TOXIC CYANOBACTERIAL BLOOMS

Two species of common edible fish, common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix), were exposed to a Microcystis spp.-dominated natural cyanobacterial water bloom for two months (concentrations of cyanobacterial toxin microcystin, 182-539 microg/g biomass dry wt). Toxins accumulated up to 1.4 to 29 ng/g fresh weight and 3.3 to 19 ng/g in the muscle of silver carp and common carp, respectively, as determined by enzyme-linked immunosorbent immunoassay. Concentrations an order of magnitude higher were detected in hepatopancreas (up to 226 ng/g in silver carp), with a peak after the initial four weeks. Calculated bioconcentration factors ranged from 0.6 to 1.7 for muscle and from 7.3 to 13.3 for hepatopancreas. Microcystins were completely eliminated within one to two weeks from both muscle and hepatopancreas after the transfer of fish with accumulated toxins to clean water. Mean estimated elimination half-lives ranged from 0.7 d in silver carp muscle to 8.4 d in common carp liver. The present study also showed significant modulations of several biochemical markers in hepatopancreas of fish exposed to cyanobacteria. Levels of glutathione and catalytic activities of glutathione S-transferase and glutathione reductase were induced in both species, indicating oxidative stress and enhanced detoxification processes. Calculation of hazard indexes using conservative U.S. Environmental Protection Agency methodology indicated rather low risks of microcystins accumulated in edible fish, but several uncertainties should be explored.

A review of the alien and expansive species of freshwater cyanobacteria and algae in the Czech Republic

The invasion and spread of non-native species of many different kinds of organisms is of increasing interest to researchers. Invasions by microscopic organisms, however, are poorly understood, and their impact on the environment is probably underestimated. We collected available data on non-native and invasive/expansive algae and cyanobacteria in the Czech Republic; we mapped their distribution and assessed their impact on local species and other real or potential risks resulting from their spread. The list of alien species in the Czech Republic contains 10 species of cyanobacteria, 9 species of Bacillariophyceae, 1 species of Dinophyta, 1 species of Ulvophyceae, 2 species of Chlorophyceae, and 1 species complex of Zygnematopyceae. The literature on the worldwide occurrence of these taxa is also reviewed.

Microcystin kinetics (bioaccumulation, elimination) and biochemical responses in common carp and silver carp exposed to toxic cyanobacterial blooms

The study investigating microcystin kinetics (bioaccumulation, elimination) and biochemical responses in common carp and silver carp exposed to toxic cyanobacterial blooms

Impact of microcystin containing diets on physiological performance of Nile tilapia (Oreochromis niloticus) concerning stress and growth

Diets containing Microcystis with considerable amounts of the cyanotoxin microcystin-LR (MC-LR) were fed to determine their impact on the physiological performance of the omnivorous Nile tilapia (Oreochromis niloticus) with regard to stress and growth performance. Four different diets were prepared based on a commercial diet (control, MC-5% [containing 5% dried Microcystis biomass], MC-20% [containing 20% dried Microcystis biomass], and Arthrospira-20% [containing 20% dried Arthrospira sp. biomass without toxin]) and fed to female Nile tilapia. Blood and tissue samples were taken after 1, 7, and 28 d, and MC-LR was quantified in gills, muscle, and liver by using high-performance liquid chromatography (HPLC). Only in the liver were moderate concentrations of MC-LR detected. The stress hormone cortisol and glucose were analyzed from plasma, suggesting that all modified diets caused only minor to moderate stress, which was confirmed by analyses of hepatic glycogen. In addition, the effects of the different diets on growth performance were investigated by determining gene expression of hypophyseal growth hormone (GH) and hepatic insulin-like growth factor-I (IGF-I). For all diets, quantitative reverse transcription-polymerase chain reaction (RT-qPCR) demonstrated no significant effect on gene expression of the major endocrine hormones of the growth axis, whereas classical growth data, including growth and feed conversion ratio, displayed slight inhibitory effects of all modified diets independent of their MC-LR content. However, no significant change was found in condition or hepatosomatic index among the various diets, so it seems feasible that dried cyanobacterial biomass might be even used as a component in fish diet for Nile tilapia, which requires further research in more detail.

Impact of microcystin containing diets on physiological performance of Nile tilapia (Oreochromis niloticus) concerning detoxification.

Nile tilapia (Oreochromis niloticus) were fed by diets supplemented with cyanobacteria containing in part the cyanotoxin microcystin-LR (MC-LR) to determine the potential impacts on detoxification. Four different diets were prepared based on a commercial diet: (1) control, (2) MC-5% (containing 5% dried Microcystis sp. biomass with 4.92 μg MC-LR g(-1) diet), (3) MC-20% (containing 20% dried Microcystis sp. biomass with 19.54 μg MC-LR g(-1) diet), and (4) Arthr-20% (containing 20% dried Arthrospira sp. biomass without MC-LR). Blood and liver samples were taken after one, 7, and 28 days and protein has been determined in plasma and liver. In the liver, impacts on detoxification were measured by glutathione-S-transferase (GST) activities and gene expression of multi drug resistance protein (MDRP). Plasma protein did not change between all four diets at any sampling time whereas liver protein was significantly elevated already after one day in Arthr-20% and after 28 days in both, MC-20% and Arthr-20%. Biochemical measurements of GST activities revealed no significant impact at any sampling time. In order to characterize the potential effect of MC-LR on MDRP, RT-qPCR method was established. However, as for GST activities no significant changes in MDRP gene expression have been observed. Thus, in summary, oral exposure of MC-LR containing cyanobacteria to Nile tilapia via feed ingestion did not impact significantly detoxification in liver concerning GST activities and MDRP expression despite biochemical composition concerning liver protein was significantly elevated by the diets containing 20% cyanobacteria biomass, regardless whether they contained MC-LR or not.

Haematological indices are modulated in juvenile carp, Cyprinus carpio L., exposed to microcystins produced by cyanobacterial water bloom

This study evaluated the influence of toxic cyanobacterial water blooms on the blood indices of the common carp, Cyprinus carpio L. Experimental fish were exposed to a natural population of cyanobacterial water blooms (mainly Microcystis aeruginosa and M. ichthyoblabe), which contained microcystins [total concentration 133-284 μg g⁻¹ (DW), concentration in water 2.8-7.4 μg L⁻¹]. Haematological indices showed marked changes in fish exposed to the cyanobacterial population in comparison with the control group. Statistical evaluation of the influence of cyanobacterial water blooms on biochemical indices of the juvenile carp showed a distinct decrease in albumin, alanine aminotransferase, total bilirubin, calcium, cholesterol, glucose, phosphorus and iron when compared to controls. Values of red blood counts [haemoglobin, haematocrit (PCV), mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration] and lactate were significantly increased compared to controls. After exposure to cyanobacterial water bloom, the carp were kept in clean water to monitor the persistence of biochemical indices. The influence of cyanobacterial populations on calcium, cholesterol, glucose, lactate, phosphorus and PCV persisted up to 28 days after conclusion of the experiment. Duration of exposure, toxicity and density of cyanobacterial water blooms had an important impact on individual haematological indices.

The influence of physicochemical properties of water on plasma indices in brook trout (Salvelinus fontinalis, Mitchill) reared under conditions of intensive aquaculture

The breeding of salmonids in intensive aquaculture has increasing importance in terms of high quality fish crude. The aim of our study was to figure out if the physicochemical properties of water can influence the physiological condition of fish organism. Blood samples were taken from the heart of 86 healthy, randomly selected brook trout (Salvelinus fontinalis) with the standard length of 242.3 ± 10.8 mm and body mass of 261.10 ± 29.81 g. Sampling was done on three trout farms in the Czech Republic in the period between autumn 2009 and summer 2011. Blood plasma was analysed for the presence of 23 plasma indices by automated blood plasma analyser. Chemical properties of water had a significant (P < 0.001) influence on the content of alkaline phosphatase, cholinesterase, amylase, lipase, total protein, albumin, P, Ca and K in plasma of the brook trout. Plasma indices were influenced especially by water temperature, oxygen saturation, and the content of ammonium ions, total nitrogen, iron and conductivity. This is the first complex study focusing on the influence of chemical and physical composition of water on blood plasma indices of brook trout. Fish, salmonids, biochemical variables, chemical properties, fish farming Development of intensive aquaculture requires the examination of the state of health of fish including also approaches that involve clinical biochemical diagnostics. Such approaches serve to identify the onset of any organ failure caused by the use of wrong feeds and to draw attention to changes in the abiotic factors of the environment and to any complications due to infection or parasitic invasion. To identify as many pathological deviations as possible, it is advisable to use more than one test reflecting the basic metabolic functions (Řehulka and Minařik 2008). Fish blood plasma chemistry is a promising area in fish biology and clinical pathology although it requires further research particularly in assessment of normal range. More studies need to be performed with a focus on the clinical analysis of blood as an indicator of the physiological state of the brook trout in aquaculture (Diouf et al. 2000; Řehulka and Minařik 2007). Moreover, apart from the inevitable differences in, e.g. methodology, fish size and strains, season and physiological condition, it is often difficult to find an exhaustive set of blood chemistry which estimates for trout in a single study (Manera and Britti 2006). The aim of the present study was to assess plasma indices in brook trout (Salvelinus fontinalis) from aquaculture system. The basic characteristics of fish organism physiological condition through selected biochemical indices of the blood plasma were examined.

The prediction of mercury bioavailability for common carp (Cyprinus carpio L.) using the DGT technique in the presence of chloride ions and humic acid

The ability of the DGT technique to predict Hg2+ bioavailability for input tissues (skin, gills, and scales) of common carp in the presence of chloride ions and humic acid (HA) was evaluated. The mercury accumulation by the DGT units and input tissues of carp decreased with an increasing concentration of chloride ions (29-180 mg L-1) and HA (0-5 mg L-1). In the presence of chloride ions and HA, statistically significant correlations (Pearsons correlation coefficients 0.731-0.954) were determined between the rate of mercury accumulation by input tissues of carp and the rate of mercury accumulation by the DGT units. The laboratory experiments suggest the possibility of using the DGT technique for predicting the mercury bioaccumulation in natural aquatic ecosystems instead of commonly used input tissues of fish.