Interactions of trace metals and different marine food chains

Abstract

There is increasing recognition of the quantitative importance of metal accumulation from dietary pathways in different marine food webs. With a simple kinetic model requiring measurements of metal assimilation efficiency (AE), metal efflux rate and ingestion activity of the relevant animals, it is possible to predict the transfer (and potential biomagnification) of metals along diverse marine food chains. In this paper, food chain transfer in different marine food chains (planktonic and benthic) is reviewed, and any potential biomagnification of metals is predicted using the simple kinetic equation. It is well recognized that metal concentrations in animals are probably not related to the trophic level in the food chain, but some metals (Hg and Zn) may potentially be influenced by the numbers of trophic interactions involved. Depending on these different trophic interactions, the potential biomagnification of metals is influenced by metal assimilation or metal efflux rate or both. Metals may potentially be biomagnified in benthic food chains; principally, in those with gastropods as top predators, as they can efficiently sequester dietary metals. The biodiminution of metals (concentration decreases at a higher trophic level) in the classical marine planktonic food chain (phytoplankton to copepods to fish) is largely the result of the effective efflux of metals by the copepods and the very low assimilation of metals by marine fish. Although many past studies have considered the physico-chemical properties of metals in prey in controlling food chain transfer, it is suggested that the physiological and biochemical processes in the herbivore or predator should be emphasized in future studies. Also, the complicated metal-handling strategies found in different marine organisms clearly need to be appreciated. KEY WORDS: Food chain · Trace metals · Biomagnification · Trophic transfer factor · Invertebrates · FishResale or republication not permitted without written consent of the publisher

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

“…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). Conversely to As, Cd, and Hg, and in agreement with our results, Pb is known not to be transferred efficiently through marine food webs (Neff 2002).…”

“…Trace elements from both natural and contaminated sources tend to concentrate in aquatic organisms, and some can be transferred up through the food chain by way of biomagnification. Consequent risk to the health of humans, as top-level predators, means the study of biomagnification is increasingly important (Wang 2002).…”

“…Because trophic relationships in marine coastal ecosystems are complex, involving numerous species and links, evaluation of trophic transfer of trace elements within the food chain is highly complicated (Wang 2002). The use of stable carbon and nitrogen isotope (d 13 C, d 15 N) analysis has allowed greater clarification of trophic relationships and food web structure, thus providing insight into the biomagnification of contaminants (Cheung and Wang 2008).…”

Heavy metals in zooplankton and decapod crustaceans from the Barents Sea

“…Both sources are integrated into accumulated concentrations in organisms. There is increasing evidence that trophic transfer may be even more important than dissolved uptake in various invertebrates (Wang, 2002). Further support of this view is provided by the fact that bioconcentration factors (BCFs) derived from field samples are often much higher than BCFs estimated from experiments regarding dissolved uptake (Kahle and Zauke, 2002b).…”

Molecular characterization of the spatial diversity and novel lineages of mycoplankton in Hawaiian coastal waters

“…Two types of food chains, namely the classical grazing food chain and the microbial food chain, dominate the flow of elements and energy in ocean ecosystems (Wang, 2002). Microbes salvage organic materials such as phytoplankton exudates and phyto-/zoodetritus from the grazing food chain (Pomeroy and Wiebe, 1993).…”