L'Impacte ecològic dels peixos introduïts a Catalunya

We review the invasive fish species introduced to Catalonia (Spain) and their mechanisms of ecological impact. Catalonia has about 15 established foreign fish species along with many others that have been translocated. These fish species, which are identical to those that have been introduced worldwide (thereby contributing to biotic homogenization), include: common carp (Cyprinus carpio), largemouth bass (Micropterus salmoides), eastern mosquitofish (Gambusia holbrooki) and many European cyprinids that are not native to the Iberian Peninsula. There are some well-documented repercussions to the native fauna, such as the impact of mosquitofish on endangered, endemic cyprinodonts. The illegal introduction by anglers continues to be one of the main culprits of this environmental problem, one that has been barely addressed by local and state authorities

Distribució espacial i ús de l'hàbitat de la comunitat de peixos a l'estany de Banyoles

En el marc d'un projecte més ampli sobre la comunitat de peixos de la conca lacustre de Banyoles, s'ha estudiat la distribució espacial de les diferents espècies així com l'ús que aquestes fan de l'hàbitat. El poblament piscícola de l'estany de Banyoles és el resultat d'un llarg historial d'introducció d'espècies exòtiques i extinció de les poblacions autòctones locals. S'ha revisat la seva composició actual detectant un total de 18 espècies (4 autòctones i 14 introduïdes) de les quals només 13 presenten una població estable. L'estudi de l'hàbitat s'ha centrat a l'Estany, l'element principal del sistema lacustre, analitzant per separat la zona litoral i la zona limnètica. En el primer cas s'han realitzat les captures d'individus mitjançant pesca elèctrica des d'una embarcació adaptada per aquesta pràctica. La totalitat del litoral ha estat dividida en trams de característiques homogènies on s'han obtingut les captures per unitat d'esforç per cada espècie. El mostreig s'ha desenvolupat entre l'estiu de 1997 i la primavera del 2000 realitzant un total de 10 campanyes de pesca. Les espècies més abundants al litoral són la perca americana (Micropterus salmoides) i el peix sol (Lepomis gibbosus), essent també presents la perca (Perca fluviatilis), carpa (Cyprinus carpio) i el gardí (Scardinius erythrophthalmus). S'han capturat altres espècies com ara anguila (Anguilla anguilla), bagra (Squalius cephalus), sandra (Sander lucioperca), carpí (Carassius auratus) i madrilleta vera (Rutilus rutilus), però són molt menys abundants en nombre. S'ha examinat, per cadascuna de les espècies, si existeix selecció de l'hàbitat i en cas afirmatiu, quin és el preferent en base a la classificació del litoral en sis tipus de vegetació predominant. Les espècies més abundants, perca americana i peix sol, ocupen tots els hàbitats disponibles però amb una densitat diferent. La perca mostra també una clara selecció de l'hàbitat a favor de les zones molt estructurades amb abundant presència de jonca litoral. Carpa i gardí seleccionen els ambients més fondos amb major presència de matèria orgànica d'origen vegetal procedent del bogar. En general els individus ocupen les zones amb una densitat de vegetació intermèdia, majoritàriament zones de jonca a l'estiu i zones amb mansega a l'hivern, on troben refugi i els recursos tròfics necessaris. La perca americana, a més, presenta una elevada fidelitat a un mateix punt del litoral al llarg de la seva vida. La zona limnètica ha estat prospectada mensualment mitjançant ecosondació, realitzant transectes perpendiculars a l'eix principal de l'Estany, cobrint la seva totalitat. La composició d'espècies s'ha obtingut a partir de les captures fetes amb xarxes (tresmalls) amb periodicitat estacional. L'anàlisi geoestadística de la densitat de peixos ha permès descriure l'estructura espacial d'aquesta a partir dels variogrames, així com la seva variabilitat tant espacial com temporal, i obtenir els mapes de densitat. A l'hivern, la densitat de peixos a la zona limnètica assoleix els seus valors mínims i els individus es troben formant agregats dispersos, pels diferents estrats de fondària. A partir de la primavera la densitat augmenta, pel reclutament i la major freqüència d'individus que abandonen el litoral; la densitat esdevé més homogènia a les primer capes de fondària. A l'estiu la densitat és màxima i l'estrat més homogeni coincideix amb la posició de la termoclina. Aquest estructura varia en disminuir la temperatura i barrejar-se la columna d'aigua, tornant a la situació hivernal. La perca i la madrilleta vera són les espècies predominants en aquest ambient, juntament amb la carpa. La seva distribució no és homogènia i respon a les característiques limnològiques de les diferents cubetes de l'Estany. Una particularitat d'aquest, relacionada amb el seu origen càrstic, es la formació d'una ploma hidrotermal que afecta la distribució dels peixos, probablement en augmentar la terbolesa. S'ha integrat l'ús de l'hàbitat de les espècies que ocupen tant la zona limnètica com la litoral a partir del seguiment d'individus, concretament de perca i bagra. S'ha utilitzat un sistema automàtic de posicionament que estima la localització dels individus marcats amb transmissor de telemetria acústica. L'anàlisi dels desplaçaments mostra un rang superior per la bagra en comparació amb la perca. Ambdues espècies mostren una orientació en els seus desplaçaments. La perca ocupa el litoral a la nit i es desplaça a la zona limnètica de dia, amb un ritme d'activitat marcat per dos màxims coincidint amb la sortida i posta de sol; en canvi la bagra mostra una major activitat nocturna amb zones de repòs properes al litoral. S'ha estimat igualment els dominis vital de cada individu marcat.

Dietary Levamisole Influenced Hematological Parameters of Juvenile Pacu, Piaractus mesopotamicus (Holmberg 1887)

Diseases outbreaks are a major concern in intensive fish farming because fish are exposed to stressors which may negatively affect their physiology. This study set out to determine effects of dietary levamisole (Levamisole HCl; SIGMA (R)) on performance and hematology of pacu, Piaractus mesopotamicus, juveniles. Fish (55.94 g) were stocked into 24 plastic aquaria (500 L; 15 fish per aquarium) and fed for 30 d with a commercial diet with 0, 50, 100, 200, 400, and 800 mg/kg levamisole, and for an extra 15 d, with a control diet in a totally randomized design trial (n = 4). Biometrical and hematological data were collected. No significant differences in growth parameters were recorded for either control or supplemented diets. Hematological parameters, such as hemoglobin, plasma glucose, white blood count (WBC), and differential leukocyte count were influenced (P < 0.05) levamisole. WBC, lymphocytes, neutrophils, monocytes, eosinophils, and special granulocytic cell numbers decreased significantly after 15 d. Dietary levamisole at 100 mg/kg diet for 15 d increased leukocyte production in juvenile pacu. However, levamisole administration for more than 15 d presented toxicity to lymphopoietic tissues. Information about long-period administration, mode of action in weight gain, effects on hematology of levamisole in freshwater fish nutrition are scarce and necessary for its safe use in aquaculture.

Thermal acclimation of locomotor performance in tadpoles of the frog Limnodynastes peronii

Previous analyses of thermal acclimation of locomotor performance in amphibians have only examined the adult life history stage and indicate that the locomotor system is unable to undergo acclimatory changes to temperature. In this study, we examined the ability of tadpoles of the striped marsh frog (Limnodynastes peronii) to acclimate their locomotor system by exposing them to either 10 degrees C or 24 degrees C for 6 weeks and testing their burst swimming performance at 10, 24, and 34 degrees C. At the test temperature of 10 degrees C, maximum velocity (U-max) of the 10 degrees C-acclimated tadpoles was 47% greater and maximum acceleration (A(max)) 53% greater than the 24 degrees C-acclimated animals. At 24 degrees C, U-max was 16% greater in the 10 degrees C-acclimation group, while there was no significant difference in A(max) or the time taken to reach U-max (T-U-max). At 34 degrees C, there was no difference between the acclimation groups in either U-max or A(max), however T-U-max was 36% faster in the 24 degrees C-acclimation group. This is the first study to report an amphibian (larva or adult) possessing the capacity to compensate for cool temperatures by thermal acclimation of locomotor performance. To determine whether acclimation period affected the magnitude of the acclimatory response, we also acclimated tadpoles of L. peronii to 10 degrees C for 8 months and compared their swimming performance with tadpoles acclimated to 10 degrees C for 6 weeks. At the test temperatures of 24 degrees C and 34 degrees C, U-max and A(max) were significantly slower in the tadpoles acclimated to 10 degrees C for 8 months. At 10 degrees C, T-U-max was 40% faster in the 8-month group, while there were no differences in either U-max or A(max). Although locomotor performance was enhanced at 10 degrees C by a longer acclimation period, this was at the expense of performance at higher temperatures.

Muscle fibre types and size distribution in sub-antarctic notothenioid fishes

The presumptive tonic muscles fibres of Cottoperca gobio, Champsocephalus esox, Harpagifer bispinis, Eleginops maclovinus, Patagonothen tessellata, P. cornucola and Paranotothenia magellanica stained weakly or were unstained for glycogen, lipid, succinic dehydrogenase (SDHase) and myosin ATPase (mATPase) activity. Slow, intermediate and fast twitch muscle fibres, distinguished on the basis of the pH stability of their mATPases, showed intense, moderate and low staining activity for SDHase, respectively. Slow fibres were the major component of the pectoral fin adductor profundis muscle. The proportion of different muscle fibre types varied from the proximal to distal end of the muscle, but showed relatively little variation between species. The myotomes contained a lateral superficial strip of red muscle composed of presumptive tonic, slow twitch and intermediate fibres, thickening to a major wedge at the horizontal septum. All species also had characteristic secondary dorsal and ventral wedges of red muscle. The relative abundance and localization of muscle fibre types in the red muscle varied between species and with body size in the protandric hermaphrodite E. maclovinus. The frequency distribution of diameters for fast twitch muscle fibres, the major component of deep white muscle, was determined in fish of a range of body sizes. The absence of fibres <20 mu m diameter was used as a criterion for the cessation of muscle fibre recruitment. Fibre recruitment had stopped in P, tessellata of 13.8 cm L-T and E, maclovinus of 32.8 cm L-T, equivalent to 49 and 36.5% of their recorded maximum sizes respectively. As a result in 20-cm P. tessellata, the maximum fibre diameter was 300 mu m and 36% of fibres were in excess of 200 mu m The unusually large maximum fibre diameter, the general arrangement of the red muscle layer and the extreme pH lability of the mATPase of fast twitch fibres are all common characters of the sub-Antarctic and Antarctic Notothenioids, including Cottoperca gobio, the suggested sister group to the Notothenidae. (C) 2000 The Fisheries Society of the British Isles.

Bioaccumulation of 210Pb and 210Po in fish tissues in a radioactive naturally enhanced area: the Peníscola marsh (Castelló, Spain)

210Pb and 210Po concentration in fish tissues from Peníscola marsh were analyzed, being this area a radioactive naturally enhanced marsh located in the East coast of Spain. Results showed that 210Po accumulation in tissues could reach values ranging from 28±8 Bq kg-1 in muscle of Cyprinus carpio, to 8558±6378 Bq kg-1 in gut content of Chelon labrosus. On the other hand, 210Pb concentrations ranged from 8±4 Bq kg-1 in muscle of Cyprinus carpio, to 475±481 Bq kg-1 in gut content of Chelon labrosus. Bioaccumulation pattern is generally 210Po&210Pb, except in spine, where more 210Pb than 210Po is accumulated. When comparing our samples to those collected as blanks, individuals from Peníscola marsh showed an enrichment in 210Po and 210Pb in their tissues compared to the blanks. Bioaccumulation factors showed that feeding is the major input route of 210Pb and 210Po into the fish body. Highest values of 210Pb and 210Po concentration in tissues were found on Chelon labrosus and Carassius auratus, being Cyprinus carpio the species with the lowest average values of 210Pb and 210Po accumulation.

Fish passage assessment at the most downstream barrier of the Ebro River (NE Iberian Peninsula)

Fish passage at artificial barriers is necessary for the conservation of healthy fish stocks. The first barrier that migratory fish encounter when ascending the Ebro River is the Xerta Weir, where a pool-type fishway was constructed in 2008. From 2007 to 2010, boat electrofishing surveys were conducted in the Ebro River downstream of the Xerta Weir to assess the potential pool of species that could use the fishway. Nine native and 12 exotic species were captured, the latter comprising 62 % of the relative abundance and 70 % of the biomass. A combination of video recording, electrofishing and trapping was used to assess the effectiveness of the fishway in facilitating the passage of fish. Eight species were detected using the fishway, of which five were native (Liza ramada, Anguilla anguilla, Barbus graellsii, Gobio lozanoi and Salaria fluviatilis) and three exotic (Alburnus alburnus, Cyprinus carpio and Rutilus rutilus). Only L. ramada used the fishway in substantial numbers. The rate of fish passage was the highest from June to August and decreased afterwards. The effectiveness of the fishway might be lowered by areas of turbulence within the fishway and by distraction flows from a nearby hydropower station

Determinação da toxicidade aguda e caracterização de risco ambiental do herbicida Roundup (glifosato) sobre três espécies de peixes

Considering their commercial importance, as these are the species of freshwater fish more commercialized in Brazil, their occurence in different kinds of aquatic environments (lakes, rivers and dams) and for being tolerant to a wide range of variation of various physical parameters and chemical water, the fish species Oreochromis niloticus, Cyprinus carpio and Colossoma macropomum were chosen for this study, furthermore, to test the toxicity we used the herbicide Roundup. The fingerlings of tilapia (Oreochromis niloticus), commun carp (Cyprinus carpio) and tambaqui (Colossoma macropomum) were submitted to the herbicide roundup in the following concentrations: 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, 0.0 (control); 13,89; 14,86; 15,83; 16,81 and 17,78 mg.L-1, and 0.0 (control); 18,06; 19,10; 20,14; 21,18 and 22,22 mg.L-1, respectively, three for 96 hours. The LC50 - 96h for O. niloticus, C. carpio and C. macropomum was 21,63, 15,33 and 20,06 mg.L-1 of the herbicide roundup, respectively. The results show that this herbicide is classified as slightly toxic to the three species. The values of dissolved oxygen, pH and temperature recorded in the aquarium control and aquarium experimental of the three fish species have remained without significant variations during the tests, which reduces the possibility of death caused by sudden variations of these parameters during the 96 hours the experiment. The values of LC50 between different species of fish were observed, noting that the species O.niloticus, C. carpio and C. macropomum showed no expressive differences. The values of environmental risk of Roundup were calculated to obtain more stringent parameters in assessing the dangerousness of those on nontargets. The risk of environmental contamination by Roundup for the Nile tilapia, common carp, and tambaqui are low for the lowest application rate (1 L.ha-1) and depths (1.5 and 2.0 m). The dilution of 100%, the highest recommended dose (5 L.ha-1) and depths (1.5 and 2.0 m) the risk is moderate for the three species. The values of the Risk Ratio (QR) were greater than 0,1, indicating that the values of the CAE and LC50 are above acceptable levels and there is a need, this study, a refinement in ecotoxicological tests

Fauna parasitária de peixes oriundos de pesque-pague do município de Franca, São Paulo, Brasil. I. Protozoários

The present work studied protozoan parasites of cultivated fishes (N = 433) from two feefishing farm situated in Franca, São Paulo, Brazil, during a period of April 1997 through March 1999. Specimens of piauçú Leporinus macrocephalus Garavello & Britski, 1988 (Anostomidae), pacu Piaractus mesopotamicus Holmberg, 1887 (Characidae) carp Cyprinus carpio Linnaeus, 1758 (Cyprinidae), Tillapia rendalli Boulenger, 1896 (Cichlidae), nile-tilapia Oreochromis niloticus Linnaeus, 1758 (Cichlidae), matrinxã Brycon cephalus Günther, 1869 (Characidae) and tambacu hybrid (male of P. mesopotamicus x female of Colossoma macropomum Cuvier, 1818) were collected. The fishes were parasitized with protozoans Ichthyophthirius multifiliis Fouquet, 1876 (Protozoa), Trichodina sp. and Piscinoodinium pillulare (Schaperclaus, 1954), Lom, 1981 (Protozoa). In the cold season (autumn and/or winter) all species of fish were infected with I. multifiliis. Higher susceptibility to Trichodina sp. was observed in L. macrocephalus, C. carpio and P. mesopotamicus compared to tambacu, B. cephalus, T. rendalli and 0. niloticus. It was not observed significant difference (P > 0.05) in the seasonal variation of Trichodina sp. and P. pillulare infection of all species. A great number of P. pillulare without significant difference (P > 0.05) was reported to L. macrocephalus, P. mesopotamicus and tambacu.

Comparative evaluation of the susceptibility of cultivated fishes to the natural infection with myxosporean parasites and tissue changes in the host

O objetivo deste estudo foi avaliar a susceptibilidade de 4 importantes peixes cultivados a parasitos esporozoários. Os peixes foram coletados bimestralmente de um tanque de cultivo, durante 1 ano. Myxobolus colossomatis e Henneguya piaractus foram encontrados nos órgãos internos e brânquias, respectivamente. A incidência de ambos os parasitos foi de 97,3% em pacu (Piaractus mesopotamicus), 33,3% no híbrido tambacu (Piaractus mesopotamicus x Colossoma macropomum), 5,6% em tambaqui (Colossoma macropomum) e 0% em carpa (Cyprinus carpio). Pacu foi o peixe mais susceptível, encontrando-se parasitado 79,2% nas brânquias, 66,7% nos rins e 50% no baço. A análise histopatológica das brânquias mostrou hemorragias, reação inflamatória com células mononucleares, fibroblastos e hiperplasia das células basais e mucosas.

Fauna parasitária de peixes oriundos de pesque-pagues do município de Franca, São Paulo, Brasil. II. Metazoários

Metazoan fauna from cultivated fishes (N = 433) in two feefishing farm of Franca, State of São Paulo, Brazil, was studied during a period of April 1997 through March 1999. Specimens of piauçú Leporinus macrocephalus Garavello & Britski, 1988 (Anostomidae), pacu Piaractus mesopotamicus Holmberg, 1887 (Characidae), carp Cyprinus carpio Linnaeus, 1758 (Cyprinidae), Tillapia rendalli Boulenger, 1896 (Cichlidae), nile-tilapia Oreochromis niloticus Linnaeus, 1758 (Cichlidae), matrinxã Brycon cephalus Günther, 1869 (Characidae) and tambacu hybrid (male of P. mesopotamicus x female of Colossoma macropomum Cuvier, 1818) were collected. A total of 29.3% was parasitized by monogenean, 9.7% with crustacean (copepodits and adults of Lernaea cyprinacea Linnaeus, 1758 and Argulus sp.) and 1.6% with myxosporean (Henneguya piaractus Martins & Souza, 1997 and Myxobolus colossomatis Moinar & Békési, 1993).The most susceptible species to myxosporean infestation was P. mesopotamicus. L. macrocephalus and P. mesopotamicus that showed a higher susceptibility to Argulus sp infestation. It was not observed significant difference (P > 0.05) in the seasonal variation of L. cyprinacea infection of all species. L. macrocephalus, P. mesopotamicus and tambacu showed a great number of P. pillulare with no significant difference (P > 0.05) between them. Monogenean infections were observed in all examined species, without significant difference (P > 0.05) in the seasonal variation. Nevertheless, occurrence of monogenean was higher in P. mesopotamicus and lower in Nile-tilapia. By the other hand, parasites number collected from P. mesopotamicus was lower in the winter. Copepodits of L. cyprinacea were found in the gills of P. mesopotamicus, tambacu and L. macrocephalus. However, adults of L. cyprinacea were observed only in the P. mesopotamicus and tambacu.

Distribuição sazonal de parasitos branquiasis em diferentes especies de piexes em pesque-pague do municipio de Guariba-SP, Brasil.

This study was accomplished with the objective of knowing the seasonal distribution of the main species of parasites causes of branchial damages to the fish from fee-fishing at Guariba, State of São Paulo. This city is situated at 21 degrees 15'22'' S, 48 degrees 18'58'' W, in altitude 595 meters. This research was conducted between April, 1997 to March, 1999. From 408 fishes examined, 29.1% of them were infested by the protozoans e metazoans. Leporinus macrocephalus showed the highest parasitism by Trichodina sp., although Piaractus mesopotamicus and Cyprinus carpio were also parasited. Piscinoodinium pillulare infestation were found in L. macrocephalus, P. mesopotamicus, C. carpio e Colossoma macropomum. Monogenetics metazoan have largely been observed in L. macrocephalus, P. mesopotamicus, C. carpio, C. macropomum e cross-bred tambacu. The incidence of this parasite was elevated in the summer for L. macrocephalus, spring for P. mesopotamicus and C. macropomum, and both seasons for cross-bred tambacu. Lernaea cyprinacea copepodes were observed in L. macrocephalus, P. mesopotamicus, C. carpio and cross- breeding tambacu, in spite of the fact that C. carpio has demonstrated high parasitism of adult form. The fish L. macrocephalus, P. mesopotamicus and C. carpio were sponged intensely by Dolops carvalhoi, in situation of high population density. Piaractus mesopotamicus was considered the species more parasited by myxosporídeos, that were also observed in L. macrocephalus and cross-breeding tambacu.

Fauna parasitária de peixes oriundos de pesque-pague do município de Guariba, São Paulo, Brasil

This study describes the occurrence and the seasonality of parasites of cultivated fish from a fee fishing farm located in Guariba, São Paulo State, Brazil (21°15'22'' S, 48°18'58'' W and 595 m of altitude), from August, 2001 to July, 2002. The presence of parasites was researched in pacu Piaractus mesopotamicus (Characidae), common carp Cyprinus carpio (Cyprinidae), nile-tilapia Oreochromis niloticus (Cichlidae), tambacu hybrid (male of P. mesopotamicus x female of tambaqui-Colossoma macropomum) and piraputanga Brycon hillari (Characidae). Results demonstrate that out of 100 fish examined, 15% were sponged for at least one of the following parasites: Trichodina sp.; monogenean helminths; copepodits of Lemaea cyprinacea; adults of L. cyprinacea; or Dolops carvalhoi. In decreasing order, the susceptibility degree of the hosts was C. carpio, P. mesopotamicus, B. hillari, tambacu hybrid and O. niloticus. In decreasing order the reported parasites were monogenean helminths, Dolops carvalhoi, Trichodina sp., adults of Lernaea cyprinacea and their young shapes.

Frequência de arraçoamento para alevinos de carpa comum

The best frequency of feeding for development of common carp fingerlings Cyprinus carpio was determined. Four hundred fish (4.88 ± 1.41 g and 6.72 ± 0.70 cm) were used, distributed in 20 tanks of 250 L each in completely randomized design with four treatments and five replicates. The four feeding strategies adopted were: providing feed once (T1), twice (T2), three (T3) and four times daily (T4) at the same amount being fractionated as described. At the end of 45 days of experiment were carried out measurements of the final weight (FW), final length (FL), weight gain (WG), feed conversion (FC), specific growth rate (SGR) and survivor (SR). It was evaluated the chemical composition of fish carcass: moisture (MT), crude protein (CP), lipids (LP) and ash (AS) and hematological analyzes performed such as erythrocyte (ER), hemoglobin (HG) and hematocrit (HT). There were significant statistical differences (P<0.01) for FW, FL, WG and SGR. For FC and SR there were no statistical differences (P>0.01). For the chemical composition the moisture, lipids and ash showed significant statistical differences (P>0.01), except only for protein (P>0.01) The hematological composition was not influenced by the feed frequency, it was not observed significant statistical difference (P>0.01) of erythrocytes, hemoglobin and hematocrit among dietary treatments. For common carp fingerlings, the provision of ration four times daily provided better final weight, final length, weight gain and specific growth rate without causing changes in the composition and hematological parameters of the fish.

The antioxidant glutathione in the fish cell lines EPC and BCF-2: response to model pro-oxidants as measured by three different fluorescent dyes

Reduced glutathione (GSH) protects cells against injury by oxidative stress and maintains a range of vital functions. In vitro cell cultures have been used as experimental models to study the role of GSH in chemical toxicity in mammals; however, this approach has been rarely used with fish cells to date. The present study aimed to evaluate sensitivity and specificity of three fluorescent dyes for measuring pro-oxidant-induced changes of GSH contents in fish cell lines: monochlorobimane (mBCl), 5-chloromethylfluorescein diacetate (CMFDA) and 7-amino-4-chloromethylcoumarin (CMAC-blue). Two cell lines were studied, the EPC line established from a skin tumour of carp Cyprinus carpio, and BF-2 cells established from fins of bluegill sunfish Lepomis macrochirus. The cells were exposed for 6 and 24 h to low cytotoxic concentrations of pro-oxidants including hydrogen peroxide, paraquat (PQ), copper and the GSH synthesis inhibitor, L-buthionine-SR-sulfoximine (BSO). The results indicate moderate differences in the GSH response between EPC and BF-2 cells, but distinct differences in the magnitude of the GSH response for the four pro-oxidants. Further, the choice of GSH dye can critically affect the results, with CMFDA appearing to be less specific for GSH than mBCl and CMAC-blue.