Trace elements in sediments, blue spotted tilapia Oreochromis leucostictus (Trewavas, 1933) and its parasite Contracaecum multipapillatum from Lake Naivasha, Kenya, including a comprehensive health risk analysis

Abstract

This study presents the distribution of 15 major and trace elements in sediments and fish and their pericardial parasites from Lake Naivasha, Kenya. The lake is one of the few freshwater lakes in the Great Rift Valley and is under strong anthropogenic pressure mainly due to agricultural activities. Its fish provide a valuable protein source for approximately 100,000 people in the area. Fish and their parasites have been acknowledged as indicators of environmental quality due to their accumulation potential for both essential and nonessential trace elements. A total of 34 specimens of the blue spotted tilapia Oreochromis leucostictus and pooled samples of their pericardial parasite, the anisakid nematode Contracaecum multipapillatum (larvae 3), were examined. Element concentrations were determined by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and graphite furnace atomic absorption spectrometry (GF-AAS). The concentrations of elements in the sediments reflected the geology of the area and did not point to pollution: none of the investigated trace elements, including Pb, Cd, Cu, and Zn, showed elevated values. In contrast, concentrations in the fish muscle were elevated for Li, Sr, Cd, and Zn, with high target hazard quotients (THQ > 0.1) indicating a potential health risk to the consumers of this fish. Fish liver showed significantly higher concentrations of the trace elements Fe, Mn, Cd, and Cu compared to the muscle and C. multipapillatum. In the parasite, Zn had the highest concentration, but the worms only minimally accumulated trace elements in relation to their fish host.

Trace Elements in Water, Sediments and the Elongate Tigerfish Hydrocynus forskahlii (Cuvier 1819) from Lake Turkana, Kenya Including a Comprehensive Health Risk Analysis

“…Otachi et al (2014) reported Li concentrations from freshwater fish for the first time, giving mean values of 299 mg/kg dw in the muscle of Oreochromis leuctostictus from Lake Naivasha, Kenya, a concentration higher but at least in the same order of magnitude as we found in H. forskahlii. The possible sequentially of Lithium has been under discussion in the recent past, but the evidence appears to be sufficient to accept lithium as essential at least for humans (Schrauzer 2002) and most probably other mammals (Anke et al 2005).…”

“…The results for the reference samples showed recovery rates between 95 and 104 %, demonstrating the appropriateness of the sample preparation used. A detailed list of recovery rates and detection limits was published elsewhere (Otachi et al 2014). Target hazard quotients (THQ) were determined for the trace elements in order to assess the risk to local residents who consume H. forskahlii.…”

“…Furthermore, a THQ of 0.1 was later suggested for non-carcinogens to account for additive effects (USEPA 2012). The THQs were calculated as described elsewhere (Otachi et al 2014). …”

“…However, the Rb concentrations we found were much lower than those reported by Guevara et al (2006) in brown trout Salmo trutta (mean 57.6 ± 5.7 mg/kg ww) and in creole perch Percichthys trucha (45.9 ± 6.2 mg/kg ww) in lakes of the Patagonia, Argentina. The study of Otachi et al (2014) reports 18.2 mg/kg Rb in muscle from O. leucostictus from Lake Naivasha. Although there is no agreement on the importance of Rb as an ultra-trace essential element to humans and other biota, some studies have shown that even low concentrations in combination with other metals such as Pb and Mo, can be toxic to fish and other organisms (Seixas and Pierce 2005;Yamaguchi et al 2007).…”

Trace element accumulation and human health risk assessment of <i>Labeo capensis</i> (Smith, 1841) from the Vaal Dam reservoir, South Africa

“…Elevated Se concentrations may also be attributed to As concentrations, as Se functions in As detoxification (Sah et al, 2013). Otachi et al (2014) found higher concentrations of Mn (2.43 µg/g dw) and Zn (604 µg/g dw) and lower concentrations of Cu (0.54 µg/g dw), Fe (14.3 µg/g dw) and Pb (0.024 µg/g dw) in the muscle tissue of Oreochromis leucostictus from Lake Naivasha in comparison to that of L. capensis. The increased levels of Zn in O. leucostictus muscle tissue may be associated with the increased Zn concentrations within the sediment of Lake Naivasha, 229.6 µg/g dw in comparison to 5.8 µg/g dw for the sediment of the Vaal Dam.…”