Modeling Metal Bioavailability for Marine Mussels

In a radiotracer study designed to evaluate the fate of metals from fish prey to predator fish, we measured the trophic transfer of 7 trace elements (Am, Cd, Co, Cr, Cs, Mn, Zn) from juvenile Mediterranean sea bream Sparus auratus to 3 predator species, the teleosts Psetta maxima and Sparus auratus, and the elasmobranch Scyliorhinus canicula. Prey S. auratus were labeled by exposure to metal radioisotopes in solution for a period of 3 wk and were then fed to predators, after which the metal retention in the predator was assessed. Mean assimilation efficiencies (AEs) of ingested metals in the predator fishes ranged from 6 to 15% for Am, to 63 to 74% for Cs; significant differences in AEs were noted between species for Co and Mn only. Efflux rate constants (k e ) of assimilated metal did not differ consistently among predators for any metals. The mean k e ranged from 0.003 d -1 for Mn in S. canicula to 0.02 d -1 for Cd and Cs in all 3 species and for Co in S. canicula. Trophic transfer factors (TTF) for each metal were determined in predator fishes to assess the potential for metal biomagnification. TTF, calculated by dividing the product of metal AE and ingestion rate (IR) by k e , exceeded 1 only for Mn, Zn and Cs. For most likely scenarios of IR and AE, TTF was <1 for these metals, suggesting that these metals will not biomagnify in piscivorous fishes.

Section: Methodsmentioning

confidence: 99%

Assimilation and retention of metals in teleost and elasmobranch fishes following dietary exposure

Mathews¹,

Fisher²,

Jeffree³

et al. 2008

“…Under steady-state conditions, Cd, Se and Zn accumulation in fish can be calculated by the following equations (Thomann 1981, Wang & Fisher 1997:…”

Section: Fish and Metalsmentioning

confidence: 99%

Exposure and potential food chain transfer factor of Cd, Se and Zn in marine fish Lutjanus argentimaculatus

Xu¹,

Wang

2002

123

115

Radiotracer techniques were employed to quantify the rates of uptake from aqueous and dietary sources, and rates of elimination of Cd, Se and Zn by a marine predatory fish, the mangrove snapper Lutjanus argentimaculatus. The relative significance of bioaccumulation of metals by fish from water and food and the food chain transfer factor were then assessed using a kinetic modeling approach. Cd and Zn in the aqueous phase exhibited an approximately linear uptake pattern over a 1 to 2 d exposure, whereas Se exhibited a 2-compartmental uptake at a low ambient concentration, with a slow initial uptake followed by a rapid increase in Se influx. Most of the accumulated aqueous Se and Zn were incorporated into the muscles, whereas Cd was evenly distributed in the viscera and the remaining tissue, with a lower proportion in the gills. The influx rates were dependent on the ambient metal concentration and were tissue-specific for each metal. The assimilation efficiency of trace metals in fish ingesting different prey (copepods, Artemia sp. and clam tissue) ranged from 6 to 24% for Cd, 32 to 68% for Se and 15 to 46% for Zn, and decreased with an increase in ingestion rate. The efflux rate constant of Cd in fish following uptake from the dietary phase (0.047 d -1 ) was higher than that following aqueous uptake (0.025 d -1 ), whereas the efflux rate constants of Se and Zn were comparable between these 2 exposure pathways. Our modeling calculations indicate that dietary uptake of Cd and Zn dominates their accumulation in fish when zooplankton are the main prey, whereas aqueous uptake may be the dominant pathway when planktivorous fish are the dominant prey for the predatory fish. Dietary uptake always dominates Se accumulation in these fish. The modeling results also indicated that the food chain transfer factor of Cd was < 0.5 in the fish regardless of the ingestion rate and the assimilation efficiency, consistent with the results of field studies. However, Se and Zn may potentially be biomagnified when the ingestion rate and assimilation efficiency are at the high end of the range possibly encountered by the predatory fish. KEY WORDS: Metals · Mangrove snapper · Exposure · Food chain · Uptake Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 238: [173][174][175][176][177][178][179][180][181][182][183][184][185][186] 2002 2001). Organ specificity in metal accumulation may also be related to the metal speciation and the regulation of essential and non-essential metals (Hanson 1997, Baskin 2000, McGeer et al. 2000, Burgos & Rainbow 2001. Although most studies have quantified the metal concentrations in fish collected from the field, where they are exposed to metals both in the aqueous and in the dietary phases, it is difficult to quantitatively distinguish the metal uptake via food or water. Such information is useful for modeling metal transport within marine food chains and the interaction between fish and their environments.Recently, the kinetic modeling approach ha...

“…feeding and assimilation) and environmental quality (e.g. dissolved organic carbon concentration and salinity) (Wang & Fisher 1997, Wang 2001.…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies have demonstrated that the bioenergetic-based kinetic model is a power tool for understanding metal bioaccumulation and bioavailability in marine herbivores such as bivalves and copepods (Wang & Fisher 1997). In the kinetic model, various physiological and geochemical parameters are identified to quantify the rates of metal intake from both the dissolved and particulate phases.…”

Section: Introductionmentioning

confidence: 99%

Cd and Se aqueous uptake and exposure of green mussels Perna viridis: influences of seston quantity

Wang¹

2002

Trace metals are available to marine bivalves through uptake from both the aqueous and dietary phases. In this study, I sought to determine if there is any interaction between these 2 exposure pathways. The uptake of Cd and Se by green mussels Perna viridis from the aqueous phase was measured at different phytoplankton concentrations (green alga Chlorella autotrophica). Controlled experiments were performed to ensure that, in the presence of algal particles, the majority of metal accumulation by the green mussels was due to uptake from the aqueous phase. The influx rate of metals was independent of the food concentration and the clearance rate of the mussels, indicating that metal uptake from the aqueous phase was not directly related to the food concentration. These results verify the assumption that metal uptake from different exposure pathways is additive and that there is no direct interaction between different routes of exposure. Metal uptake by green mussels was further tested after exposing the mussels to neurotransmitters (serotonin which stimulates ciliary pumping and dopamine which inhibits ciliary pumping). Complete inhibition of ciliary pumping was reached after addition of 100 µM of dopamine. Despite changes in the pumping activity due to exposure to neurotransmitters, there was no evidence showing the reduction or enhancement of metal uptake. A bioenergetic-based kinetic model was then employed to model the influence of seston quantity on the exposure pathways of metals in the mussels. Our calculations indicated that the seston quantity substantially influences the relative importance of aqueous versus dietary exposure, primarily due to the dependence of a green mussel's ingestion activity on seston quantity. At a higher seston concentration, the exposure pathways are not influenced by the change in seston concentration due to the maintenance of a maximum ingestion rate and pseudofeces production.KEY WORDS: Metals · Mussels · Exposure pathway · Uptake · Cadmium · SeleniumResale or republication not permitted without written consent of the publisher