The Internal Distribution of Nickel and Thallium in Two Freshwater Invertebrates and its Relevance to Trophic Transfer

Abstract

Although nickel and thallium are present at potentially harmful concentrations in some lakes, there is little information on their bioaccumulation and transfer up aquatic food webs. To measure the propensity of animals for accumulating and transferring these contaminants along food chains, we exposed two common types of invertebrates, an insect (Chironomus riparius) and a worm (Tubifex tubifex), to these metals spiked into sediment. We then measured the subcellular distribution of Ni and Tl in these invertebrates to estimate the likelihood that these metals will have toxic effects on these prey or be transferred to higher trophic levels. In both species, at least half of their Ni and TI was present in fractions that are purportedly detoxified (granules and metal-binding proteins). Furthermore, based on information in the literature concerning prey subcellular fractions that are likely to be trophically available (TAM), we estimate that much of the Ni and TI in these animals (43-84%) is available for transfer to a predator. To test this prediction, we fed these invertebrates to the alderfly Sialis velata, and measured the efficiency with which this predator assimilated Ni and Tl from each prey type. The majority of both trace metals (58-83%) was assimilated by the predator, which suggests that these contaminants would be easily transferred along aquatic food chains and that models describing Ni and Tl accumulation by aquatic animals should consider food as a source of these metals. The proportion of metal that could potentially be taken up by a consumer (% TAM) and the actual percentage assimilated by S. velata fell on or reasonably close to a 1:1 line for the 4 prey-metal combinations.

Enzymatic validation of species‐specific protocols for metal subcellular fractionation in freshwater animals

“…Thus, studies aiming to identify the so‐called TAM fractions will only be slightly affected by this overlap since most of them consider the TAM to be formed of the combination of the mitochondrial, lysosomes/microsomes, and cytosolic fractions at least (Wallace and Luoma ; Rainbow et al ). On the other hand, results from studies on metal subcellular detoxification, especially in invertebrates (Buchwalter et al ; Dumas and Hare ; Bednarska and Świątek ), must be considered with caution if their mitochondrial fraction has not been previously validated for their working organism. Indeed, mitochondria is regarded as an important metal sensitive fraction (MSF).…”

Antioxidative responses in Tubifex tubifex against thallium induced oxidative stress

“…Little is known about the toxic mechanisms induced by Tl in aquatic organisms. Previous studies on Tubifex worms were mainly focused on the distribution of Tl in these animals or discussed the acute toxic effects on their survival [20,21]. Here, we investigated changes in the levels of selected biomarkers (MT, total GSH, GPx, GST and CAT) in T tubifex, in order to clarify the precise role of antioxidant mechanisms in these worms in relation to Tl toxicity.…”

Bioaccumulation of waterborne Ni in Dreissena polymorpha: A stable isotope experiment to assess the effect of zinc, calcium, and dissolved organic matter

“…The Ni bioaccumulation processes have been less well studied than those of other metals such as Cd, Cu, or Zn, despite the high levels of Ni concentrations reported in different aquatic systems [1] and the classification of Ni as a priority substance in the European Water Framework Directive (directive 2008/105/CE of the European Parliament and Council). Some recent studies have focused on the bioaccumulation of dietborne Ni [2] and others on the waterborne uptake of Ni by aquatic organisms exposed to sublethal concentrations [3]. However, few studies have focused on dissolved Ni accumulation by aquatic organisms exposed to environmentally realistic concentrations [4][5][6][7].…”