Bioaccumulation of aluminium and iron in the food chain of Lake Loskop, South Africa

Abstract

Concentrations of total Aluminium (Al) and Iron (Fe) were determined in Lake Oreochromis mossambicus was along a mean sequence of intestine > yellow body fat > brain > gills > liver > heart > white body fat, while the mean sequence of total Al and Fe in Micropterus salmoides was: intestine > gills > liver > heart > brain > white body fat. From the levels of Al detected in the yellow body fat of the studied fish species Oreochromis mossambicus, we suggest that this phenomenon may be related to the feeding habits of this species. Furthermore, the intake of certain species of phytobenthos by Oreochromis mossambicus could have played a role in the bioaccumulation of Al in the food chain and the possible development of pansteatitis in predators at higher trophic levels.

Impact of temporary desiccation on the mobility of nutrients and metals from sediments of Loskop Reservoir, Olifants River

“…Despite significant efforts to determine the cause of pansteatitis at both locations, the ultimate cause remains elusive. Potential causes that have been explored include opportunistic piscivory following fish kills (Dabrowski et al, 2014a); bioaccumulation of Al and Fe in the food chain (Oberholster et al, 2012); and altered aquatic food-webs (Huchzermeyer et al, 2011). Outbreaks of pansteatitis in aquatic fauna concurrent to blooms of M. aeruginosa have been previously documented (Nichols et al, 1986;Neagari et al, 2011); however, no definitive link between the disease and cyanobacteria has been established.…”

Ecosystem change and the Olifants River crocodile mass mortality events

“…The condition affects fat depots and renders the crocodiles stiff and lethargic and unable to hunt, and death is thought to be through starvation or drowning. Pansteatitis is also diagnosed in sharptooth catfish, Clarias gariepinus (Burchell), in the same area of Kruger National Park in which the crocodile mass mortalities occur (Huchzermeyer et al 2011) and in Lake Loskop it is prevalent in Mozambique tilapia, Oreochromis mossambicus (Peters) (Oberholster et al 2011). Although the cause of the disease is dietary, the co-occurrence of pansteatitis in crocodiles and fish at two different locations of the same river catchment is not related to a potential trophic relationship as the disease is not contagious through ingestion.…”

“…The pansteatitis epidemic in Lake Loskop followed mass fish die-offs and is attributed indirectly to water pollution from upstream mining, agriculture and human urban waste (Ashton 2010, Oberholster et al 2011). If the bioaccumulation of pollutants is causing the disease, then it has severe implications for other water users in the catchment.…”

“…Although the disease is rare in wild animals it has brought the Nile crocodile, Crocodilus niloticus Laurenti, population at Lake Loskop in the upper Olifants River Valley, South Africa, to the brink of extinction (Ashton 2010, Botha et al 2011. Since 2008 crocodile mass mortalities from pansteatitis have also become a seasonally recurring event downstream in an area known as the Olifants River Gorge between the confluence of the Olifants River with the Letaba River in the Kruger National Park, South Africa, and Lake Massingir, Mozambique (Osthoff et al 2010, Ferreira and.…”

Chlorinated, brominated, and fluorinated organic pollutants in Nile crocodile eggs from the Kruger National Park, South Africa

“…Parasitic and bacterial diseases have been excluded. The exact cause(s) of the steatitis is not yet known, but speculation includes microcystins from cyanobacteria in the water and food of the crocodiles (Myburgh and Botha, 2009), trapping of pollutants settling out of the water due to the effect of the river slowing down in the upper reaches of the Massingr Dam across the border in Mozambique (Osthoff et al, 2010), crocodiles feeding on dead and rancid fish caused by anthropogenic ecosystem impacts (Ashton, 2010), crocodiles feeding on dead and rancid fish from fishnets (Huchzermeyer et al, 2011), broad-scale cascades of environmental deterioration and pollution (Ferreira and Pienaar, 2011), crocodiles feeding on local catfish (Clarias garipienus) with steatitis with no known cause but pollution is suspected (Huchzermeyer et al, 2011), changes in the food web due to changes in the ecosystem, combined with a yet to be found extralimital fish species as vector of the cause (Woodborne et al, 2012), high concentrations of aluminium in the body fat of Nile tilapia (Oreochromus mossambicus) that interferes with cellular metabolism (including lipid-peroxidation) and affects predators such as crocodiles (Oberholster et al, 2012), a seasonal dietary change due to upstream migration of alien silver carp (Hypophthalmichthys molitrix) with a fatty acid composition different from local fish (Huchzermeyer, 2012).…”