Biomagnification of Trace Elements in the Aquatic Food Web in the Mekong Delta, South Vietnam Using Stable Carbon and Nitrogen Isotope Analysis

Abstract

In the present study, we report the concentrations of 21 trace elements (V, Cr, Mn, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Hg, Tl, Pb, and Bi), as well as the results of the analysis of stable carbon and nitrogen isotopes, of the various biota that make up the food web in the main stream of the Mekong Delta near Can Tho, South Vietnam. A significant trophic level-dependent increase was found in concentrations of Se, Rb, and Hg with increasing delta(15)N, indicating that an overall biomagnification of these elements occurred. However, the increase of Hg concentration per trophic level was lower than in previous studies. In contrast, the concentration of Mn showed an opposite trend in the food web of the Mekong Delta. In addition to these overall trends, the present study revealed that the biomagnification profiles of trace metals differ between crustaceans and fishes; concentrations of Mn, Cu, Zn, As, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, and Pb were significantly higher in crustaceans, whereas fishes showed higher concentrations of Cr, Rb, and Hg (trophic level determined by delta(15)N). The differences in the biomagnification profile between the major taxa might be attributed to differences in metal accumulation and in detoxification abilities such as possessing a metal-binding protein, e.g., metallothionein (MT).

Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil

“…As a whole, the biota of the Santos shelf had low Hg concentrations, comparable with values reported for the same species from the Rio de Janeiro coast (Bisi et al 2012, Di Beneditto et al 2012, Kehrig et al 2013) and with species from others regions of the world (Prudente et al 1997, Bargagli et al 1998, Anan et al 2005, Rigét et al 2007, Ikemoto et al 2008, Lavoie et al 2010. Based on the assumption that marine fish are made up of 60−80% water (Ciancio et al 2007, Eder & Lewis 2005, Ikemoto et al 2008) and the fact that our data are based on dry weight, the Hg concentrations of the 23 species analysed were under the set limit of 0.5 µg g −1 wet weight (approximately 1.67 µg g −1 dry weight, assuming 70% water) for safe fish consumption (WHO 1976, ANVISA 1998.…”

“…Based on the assumption that marine fish are made up of 60−80% water (Ciancio et al 2007, Eder & Lewis 2005, Ikemoto et al 2008) and the fact that our data are based on dry weight, the Hg concentrations of the 23 species analysed were under the set limit of 0.5 µg g −1 wet weight (approximately 1.67 µg g −1 dry weight, assuming 70% water) for safe fish consumption (WHO 1976, ANVISA 1998. Only 2 individual samples of the guitarfish had THg levels (1.74 and ) higher than this limit.…”

Trophic Transfer of Trace Elements in an Isotopically Constructed Food Chain From a Semi-enclosed Marine Coastal Area (Stagnone di Marsala, Sicily, Mediterranean)

“…Although As (Suedel et al 1994), Cd (Dietz et al 2000;Cheung and Wang 2008) and especially Hg (Dietz et al 2000;Ikemoto et al 2008) are acknowledged to have biomagnification potential, this process is not obvious. There are also cases where there is a lack of trace metal increase along marine food webs (Dietz et al 2000;Dehn et al 2006;Marín-Guirao et al 2008), probably due to the low assimilation efficiencies and high efflux rates of trace metals in marine organisms, which decreases their potential for biomagnification (Wang 2002).…”

Biomagnificación de mercurio en la cadena trófica del Delfín Moteado del Atlántico (Stenella frontalis), usando el isótopo estable de nitrógeno como marcador ecológico

“…En este estudio, la pendiente (= 0,26) de la regresión lineal simple entre el logaritmo de las concentraciones del Hg y el isotopo estable del  15 N, que representa el grado total de la biomagnificación del Hg (Lavoie et al 2013), ha mostrado que la cadena trófica costera tropical presentó un poder de biomagnificación para el Hg dentro de lo que se encuentra en el reportado en estudios previos en los diversos ecosistemas tropicales marinos (0,16 ± 0,08) y en ecosistemas costeros (0,19 ± 0,08) (Lavoie et al 2013), así como, en la costa de Río de Janeiro (Brasil) (Bisi et al 2012, Di Beneditto et al 2012, Kehrig et al 2013, el Golfo de San Lorenzo (Canadá) (Lavoie et al 2010), el Norte del Golfo de México (México) (Senn et al 2010), el Delta del Mekong (Vietnan) (Ikemoto et al 2008) La relación significativa encontrada entre el Hg y el  15 N muscular sugiere que las preferencias de forrajeo individuales permanecen relativamente constantes durante períodos prolongados, lo que indica un grado de adherencia a la dieta y a las áreas de alimentación, como se ha encontrado en lo reportado en estudios previos (Di Beneditto et al 2012, Kehrig et al 2013). …”