Figure 17 - uploaded by Byron Grant
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Section of a fresh gill filament (G) viewed at low magnification (X100) under a light microscope. Note the numerous Ichthyophthirius parasites (arrows) that have taken on a dark appearance when illuminated from behind. Although some parasites have broken free of the gill tissue, the majority are still embedded in the epithelium of the gill. The inset shows the characteristic pale U-shaped nucleus of this holotrichous protozoon
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There is a general lack of information on inland commercial fisheries in South Africa. The primary objective of this study was to provide a retrospective assessment of commercial fisheries in the Free State Province based on the assessment of catch data from fisheries operating for the period 1979–2014. Permits were issued for commercial operators...
Citations
... For complete infestation and feed obtaining, they employ a physiological strategy of toxifying the hosting fish via their injection with digestive fluids [16,20]. As for the fish parasitic copepods, they are either females possessing strong structural facilities for fish body infestation, or tiny-sized individuals capable of fish endoparasitism via sneaking inside strategy [23,24]. ...
... These ectoparasitic Branchiurans were reported to cause epidemiology in several kinds of water bodies worldwide [47,52]. Grant and his coworkers [24] displayed several skin irritations and inflammations at the attachment sites of fish lice heavy infestation as shown in Figure 4. Argulus spp. bodies are oval to rounded, flattened dorso-ventrally, and wholly covered dorsally by a horseshoe-or rounded-shaped carapace. ...
... having characteristic paired eyes, suckers, legs, and egg sacks; low magnification under the light microscope. Irritations and inflammations are appeared at the sites of the parasites' attachment [24]. ...
Several aquatic arthropodan classes, including Arachnida, Crustacea, and Ostracoda can parasitize on fish and might cause discomfort or serious harm to their tissues. These organisms can parasitize fish through either obligatory, facultative, or opportunistic relationships according to their behavior or the surrounding conditions. Free-living arthropods may be induced to parasitize fish by various physiological, environmental, or biological stimuli. Some other non-fish parasites can switch their behavior towards fish parasitism. On one hand, members of both Classes Arachnida and Ostracoda are free-living and may exhibit opportunistic parasitism of fish through nocturnal predation or attacking weakened or captivated fish. On the other hand, Class: Crustacea is wide and comprises true fish parasites, non-fish parasites, and non-parasitic forms included in three Orders: Isopoda, Branchiura, and Copepoda. Isopods are efficient attackers targeting fish body surfaces, buccal cavities, and muscles through hydrodynamic impairment, sneaking as couples, and flesh-burrowing strategies. Branchiurans are true ectoparasites having well-developed senses for host localization and then follow a physiological strategy of injecting fish with toxic digestive fluids. When it comes to fish parasitic copepods, they are either females with robust structural features for infesting fish bodies or tiny-sized individuals capable of fish endo-parasitism by sneaking inside. Notably, the free-living and the non-fish parasitic crustaceans might be forced to parasitize fish facultatively, transitory, or occasionally. Parasitic and predatory arthropods possess structural facilities besides employing behavioral tactics for handling fish bodies successfully. The current manuscript surveyed the different strategies and unusual environmental conditions that facilitate fish parasitism by the aquatic Arthropods.
... The liver's propensity to detoxify and store toxic substances makes it a popular environmental biomarker (Stori et al., 2014). In fish, the kidneys are one of the bodily organs in charge of excretion and water balance regulation (Byron, 2014). The heart circulates blood (Graham and Dickson, 2004). ...
... The heart circulates blood (Graham and Dickson, 2004). Direct air oxygen absorption is possible through the gills (Byron, 2014). It is widely known that several research on the contact between pollutants and African Catfish (Clarias gariepinus) have been carried out. ...
This study examined how crude oil from an oil exploration business in Delta State affected juvenile African catfish's blood, gills, kidney, heart, and liver. 25 juvenile African catfish were employed in the study, divided into 5 groups (5 per treatment) and used for the study. The juveniles were exposed to five concentrations of crude oil (0%, 0.1%, 0.3%, 0.5%, and 1%) for a period of 9days. At the end of the test period, anti-oxidant activities were carried out on the blood, kidney, heart, and liver of the juveniles. The results of antioxidant parameters revealed a significant difference (p < 0.05) between the control and exposed groups, which according to previous studies indicates oxidative stress. Malondialdehyde (MDA) content increased in the serum of exposed groups except 0.5% crude oil contaminated group when compared with the control group. Ascorbic acid content decreased in the serum of all exposed groups when compared with the control group. In the control stock, none of the juveniles displayed any degeneration. In conclusion, this research has shown that exposing juvenile Clarias gariepinus to crude oil, even at low concentrations, may cause antioxidant alterations in the fish's blood, kidney, heart, liver, and gills
... The liver is frequently used as an environmental biomarker due to its capacity for detoxification and storage of harmful components (Stori et al., 2014). The kidneys are one of the body organs responsible for excretion and water balance management in fish (Byron, 2014). The heart pumps blood (Graham and Dickson, 2004). ...
... The heart pumps blood (Graham and Dickson, 2004). The gills can absorb oxygen directly from the air (Byron, 2014). ...
This study investigated the effect of crude oil from an oil exploration company in Delta State on the blood, gills, kidney, heart and liver of Juvenile African Catfish (Clarias gariepinus). Twenty-Five Juvenile African Catfish were separated into 5 groups (5 per treatment) and used for the study. The juveniles were exposed to five varying concentrations of crude oil (0%, 0.1%, 0.3%, 0.5%, and 1%) for a period of 9days. At the end of the test period, biochemical activities were carried out on the blood, kidney, heart, and liver of the juveniles. The results of biochemical parameters revealed a significant difference (p < 0.05) between the control and exposed groups, indicating metabolic damage and a degenerative process. Alanine transaminase (ALT) increased in the serum, gills, kidney, heart, and liver of all exposed groups when compared to the control group serum and tissues. Superoxide dismutase (SOD) activity of kidney decreased across all exposed groups when compared to the control group. Catalase (CAT) activity increased across the serum of all contaminated groups when compared with the control group. All the juveniles held in the control stock showed no degradation. The severity of damage to the gills, heart, kidney and liver depends on the concentration of the pollutants and the period of exposure. Conclusively, this study has revealed that exposure of juvenile Clarias gariepinus to even low concentrations of crude oil may induce biochemical changes in the blood, kidney, heart, liver and gill of the fish.
... In addition, illumination and the slow swimming speed in the dark are factors influencing the fish's susceptibility to the parasitic infestations [47]. Parasitic infestations and parasites development are induced by the higher water temperatures; therefore, their seasonal prevalence is most often in Summer [44]. On contrary, egg hatching of the crustacean parasites is routinely going at a much slower rate throughout the summer and accelerates in the winter [48]. ...
... Swelling of the attachment sites associated with erythematous and hemorrhagic lesions are the common signs of Copepoda and Branchiora infestations [19]. Skin damage and inflammations were reported at the anchor worm attaching areas [44]. Obstructed gills and anoxia were also reported as signs of crustacean ectoparasites [18]. ...
Crustaceans during a parasitism relationship with fish cause biological disruption and diseases to the hosting fish that threaten their life. Several crustacean groups were reported to parasitize different fish species as definitive hosts. Copepods, Isopods, and Branchiura are the major fish parasitic groups under the crustacea. They are mainly ectoparasites and occasionally, the small and microscopic members can infest the internal organs of their fish hosts. The infected fish are suffering from serious clinical signs and the infested organs are usually suffering from severe pathological disruptions and lesions. Treatment is taking place by several chemical and biological facilities. Here in the current article, the major crustaceans that parasitize on fish are reviewed by describing their corresponding harms to the hosting fish. Factors affecting the prevalence of the crustacean parasites and some of their hazardous effects on the infected fish were considered. In addition, trials for the chemical and biological control of the crustacean infestations are summarized.
... Due to its ability to detoxify and store hazardous substances, the liver is commonly utilized as an environmental biomarker (Stori et al., 2014). One of the bodily organs in charge of excretion and controlling the water balance in fish is the kidney (Byron, 2014). Blood is pumped by the heart (Graham and Dickson, 2004). ...
... Blood is pumped by the heart (Graham and Dickson, 2004). The gills may immediately take in oxygen from the air (Byron, 2014). ...
This research looked at how crude oil from an oil exploration business in Delta State affected juvenile African catfish's blood (Clarias gariepinus). 25 juvenile African catfish were employed in the study, divided into 5 groups (5 per treatment) and used for the study. The juveniles were exposed to different concentrations of crude oil (0%, 0.1%, 0.3%, 0.5%, and 1%) for a period of 9days. At the end of the test period, haematological activities were carried out on the blood of the juveniles. The findings revealed a difference (p < 0.05) in haematological parameters between the control and exposed groups, which, according to previous research, indicates a decrease in oxygen supply, resulting in a decrease in respiratory response and oxidative stress. Haemoglobin of 0.1% crude oil contaminated group showed a decrease in activity when compared to the control group. Lymphocytes showed an increase across all contaminated groups when compared to the control group. All of the juveniles kept in the control stock exhibited no degeneration. In conclusion, this research has shown that even low amounts of crude oil can cause haematological abnormalities in the fish's blood, kidney, heart, liver, and gills.
... It was not possible to estimate the actual concentrations of pyrethroids the fish were exposed to, as at the time of the first notification of the spillage, on October 13th, no water samples had been collected from the Sorgaglia Channel. According to some fish kill management protocols tailored for investigating these episodes [1,35], water samples should be readily collected within the immediate area of the event, but also from upstream, where no mortalities are observed, and downstream. In the mortality event we investigated, the dead fish were noticed at a later stage after the pyrethroids spillage occurrence and, moreover, sampling activities were performed according to the above mentioned protocol only 5 days after the dead fish had been noticed. ...
Introduction:
Fish kills are events of strong emotional impact on the population because of the frequent suspicion that they can be the result of serious pollution accidents. As a matter of fact, they are often due to natural occurrences, such as low levels of dissolved oxygen in the water, but in many cases the causes remain unknown. Fish are particularly sensitive to pesticides and pyrethroids are reported to be the most ecotoxicologically active in the aquatic environment. Nevertheless, the reported cases of massive wild fish mortalities due to these toxicants are very few. This paper describes a fish kill episode occurred in the Padua Province (Veneto Region - North Eastern Italy) which involved several fish species and for which it was possible to identify the cause in the presence of pyrethroids in the water.
Case presentation:
When a whitish liquid coming from the rainwater drain of an industrial area was seen to be spilling into a drainage channel, a fish massive mortality was noticed and investigated. The collected water samples showed the presence of relevant concentrations of cypermethrin, permethrin, deltamethrin and tetramethrin. Analyses on the fish tissues revealed the presence of cypermethrin and permethrin at a concentration range of 476-2834μg/kg and 346-2826μg/kg on a lipid basis, respectively.
Discussion:
According to the results of the performed analyses, we can reasonably state that the described episode had been caused by the exposure of biota to high concentrations of pyrethroids. The present case report significantly contributes to the limited literature available on pesticides-related fish kills. Moreover, it highlights the importance of sharing protocols for fish kill management at a national level, as this would help to better define the roles of the different institutions involved and to improve the investigation and the reporting of these events.
Rising temperatures, drought, and oxygen depletion may be the greatest threats to aquatic animals in the twenty-first century. As a robust body of literature suggests, large-bodied fish are among the most vulnerable organisms in times of rapid climate change. While earlier studies showed an interspecific correlation between body size and sensitivity to hypoxia and thermal stress, comparisons within species remain debated. This review marshals a diverse body of literature on this topic, ranging from physiological studies to field reports and fish kill manuals, and evaluates the evidence for intraspecific size effects on hypoxia tolerance. While experimental studies and fisheries management literature sometimes contradict each other, we show that there is strong evidence for size effects on hypoxia tolerance within fish species. We argue that bringing fisheries management literature and physiological studies into a dialog with each other is of crucial importance in times of rapid climate change.
