Investigations on Mass Mortalities among Oreochromis Niloticus at Mariotteya Stream, Egypt: Parasitic Infestation and Environmental Pollution Impacts

Abstract

The present study was carried out to determine the possible causes of an emergent event of respiratory distress with consequent mass mortalities among Nile fish, Oreochromis niloticus (O. niloticus) at Mariotteya stream, an intrastate tributary of River Nile, Egypt. The area of incident extended from Shabramant till Abouseer city (along 4 km distance) with the direction of water current. Field visits have recorded thousands of dead large sized fish on both sides of the stream while huge numbers of fish of different size accumulated on the water surface showing typical signs of asphyxia. It was also noted that Mariotteya water body is being subjected to multiple sources of pollution through the dumping of improperly treated organic and inorganic chemical wastes in addition to sewage materials. Results of field and laboratory investigations have revealed that, all the examined 60 fish samples were heavily infested with different types of parasites including zoonotic species: Cichlidogyrus arthracanthus (monogenea), Lamproglena monody and Ergasilus sarsi (Copepod), Myxobolus dermatobia, Chilodonella hexastica, Trichodina truttae, Trichodina fultoni, Cryptosporidium spp. and Balantidium spp. (Protozoa), Acanthosentis tilapae.(Acanthocephala), Clinostomum spp., Euclinostomum spp., Heterophid and Prohemistomatid metacercarae (larval of Trematodes). The physical and chemical examinations of water samples and the analysis of heavy metals concentration indicated marked abnormal water quality parameters and environmental pollution which might be incriminated as a primary stress factor that promoted the invasion of parasites as a secondary stress factor. The study concluded that both factors would have interacted to produce this catastrophic intense case of respiratory distress and mass mortalities. The impact of the recorded parasitic infestation and environmental pollution was briefly discussed.

Eutrophication, Ammonia Intoxication, and Infectious Diseases: Interdisciplinary Factors of Mass Mortalities in Cultured Nile Tilapia

“…Abdelaziz and Zaki (2010) investigated an event of mass mortality in Nile Tilapia Oreochromis niloticus and African Catfish Clarias gariepinus at Mariotteya Stream, Egypt, and attributed the problem to the higher levels of phenolic and toxic un-ionized ammonia concentrations, which could account for respiratory distress and mass mortalities. Environmental pollution and water quality deterioration in the aquatic environment might be incriminated as primary stress factors that promoted the invasion of secondary bacteria and yeast, such as Pseudomonas fluorescens and Candida albicans (Eissa et al 2013), and multiple zoonotic parasites (as reviewed by Mahmoud et al 2014). Several infectious diseases, such as streptococcosis, vibriosis, photobacteriosis, branchiomycosis, saprolegniasis, and many others, have been reported in disastrous cases of mass mortalities in cultured and wild fish populations worldwide (Al-Harbi 1994;Perera et al 1994;Paperna and Smirnova 1997;Yuasa et al 1999;Glibert et al 2002;Hussein and Hatai 2002;Gaikowski et al 2003;Villamil et al 2003;Zorrilla et al 2003;Mohamed et al 2004;Evans et al 2006b;Ebrahim 2011;Geng et al 2014;Abu-Elala et al 2015).…”

Effects of Lead and Cadmium Accumulation on Survival and Growth of the Nile Tilapia (Oreochromis niloticus)

“…The toxic effects of heavy metals on fish are multi-directional and manifested by numerous changes in physiological and chemical processes (Emere & Dibal, 2013;Javed & Usmani, 2017). The presence of lead and cadmium at low concentrations in water may lead to bioconcentration and accumulation of these metals in various organs of fish and may cause functional disturbances (Mahmoud et al, 2014;Paul & Small, 2021). According to Li & Xie (2018), fish exposed to an acute lethal concentration of cadmium are related to the loss of sodium ions, which causes disruption of the cardiovascular system, which leads to fish kill.…”

Ecoepidemiology and Potential Transmission of Vibrio cholerae among Different Environmental Niches: An Upcoming Threat in Egypt

“…Spatially, the characteristics of the Nile River ecosystem reflect the impact of the control of river water flow through its length that categorizes the Nile River into three zones: the High Dam lake in Aswan, Aswan to Nile Cairo, and the Nile Delta [ 13 , 14 ]. In natural ecosystems, salinity is one of the most important water parameters that can alter species distribution, life dynamics, biodiversity, and faunal composition, as different spatial characteristics are influenced by climatic, topographical, socioeconomic, and anthropogenic factors [ 28 ].…”

“…Environmentally, the high self-purification and assimilation capacity of water from the Nile has resulted in the Nile being listed as a moderately clean river. Even so, it suffers from localized pollution challenges that affect the water quality and ecosystem along its length from Aswan to the Delta [ 13 , 14 ].…”