Retention of elements absorbed by juvenile fish (Menidia menidia, Menidia beryllina) from zooplankton prey

Abstract

Radiolabeled copepods (Acartia spp.) were fed to juvenile silversides (Menidia menidia and Menidia beryllina) to study element absorption in the fish. Copepods were reared from nauplii in the presence of different radiotracers (i*C, lo9Cd, 57Co, 32P, 35S, '?Se, or "'Zn) and were analyzed for relative concentrations of these elements in their tissue fractions. Copepod exoskeletons contained nearly all of the trace metals (>97%), 60% of the Se, and less than half of the C, P, and S accumulated by the copepods. Within the nonexoskeleton tissues of the copepods, nonpolar (CHCl, extractable) material contained 34 and 24% of the total C and P, but only 8 and 2% of the total S and Se Absorption efficiencies of trace metals in juvenile silversides (2.7% for Cd, 2.1% for Co, 6.2% for Zn) were an order of magnitude lower than those for nonmetals (29% for Se, 50% for S and C, 60% for P). The absorption efficiencies in the juvenile silversides of all seven elements studied were directly related to the percent of each element in the nonexoskeleton fraction of the copepod prey, indicating that the fish absorbed the soft tissues of the copepods and egested the chitinous exoskeleton and its associated elements.Although trace metal concentrations and concentration factors generally decrease from algae to fish in aquatic food webs, the accumulation of harmful levels of trace metals through the ingestion of contaminated food is still a threat to aquatic carnivores and the animals that consume them (Rainbow 1989). In carnivorous fish, trace metal accumulation ' Present address:

Significance of subcellular metal distribution in prey in influencing the trophic transfer of metals in a marine fish

“…Reinfelder and Fisher (1994) quantified the assimilation of C, Cd, Co, P, S, Se, and Zn in two marine fish, Menidia menidia and M. beryllina, fed the copepod Acartia spp. They suggested that the AEs of elements in fish were directly correlated with the metal distribution in the nonexoskeleton fraction of the copepod prey.…”

“…The assimilation efficiency (AE) indicates the fraction of ingested metal remaining in the fish body after the undigested materials are evacuated. Many studies have determined the AEs of different metals in a wide range of aquatic organisms, including fish (Reinfelder and Fisher 1994;Zhao et al 2001;Long and Wang 2005). However, mechanisms underlying the dietary assimilation of metals in marine fish are not yet clearly understood.…”

“…It has been shown that different prey resulted in a variation of metal AEs in fish (Ni et al 2000; Xu and Wang 2002), suggesting that different forms of metals in the food may influence the availability of metals. Some previous studies have indicated that the cytosolic distribution of metals in marine phytoplankton is important in dietary assimilation by marine herbivores (Reinfelder and Fisher 1991;Wang and Fisher 1996;Chong and Wang 2000), but assimilation in marine predators appears to be more complicated. Recently, there has been an increasing awareness of the subcellular fate of metals in prey organisms and of how the subcellular metal forms may subsequently affect the trophic transfer to the next level Vijver et al 2004).…”

Assimilation and retention of selenium and other trace elements from crustacean food by juvenile striped bass (Morone saxatilis)

“…Se found in tissues of fish is almost entirely derived from diet (Lemly 1982). Many other trace elements, including Cd, Co, Mn, and Zn, are also predominantly derived from ingested food by bivalves and copepods (e.g., Reinfelder and Fisher 1991;Wang et al 1996;Wang and Fisher 1998a) and are readily assimilated from food by fish (e.g., Pentreath 1973a,b). Clearly, a predictive understanding of the variables affecting accumulation of Se and other trace elements from food by fish is needed to properly evaluate the biotic and ecosystem level effects of trace element contamination, and to accurately assess the viability of mitigating management strategies.…”

Contribution of X-Ray Spectroscopy to Marine Ecotoxicology: Trace Metal Bioaccumulation and Detoxification in Marine Invertebrates

“…Many authors have suggested that the subcellular distribution of metals is critical for metal assimilation in predators (Amiard-Triquet et al, 1993;Nott & Nicolaidou, 1990;Reinfelder & Fisher, 1994;Wang & Rainbow, 2000). If we consider invertebrates as prey species, it is important to know how metals are distributed in animals because physicochemical characteristics of these contaminants (in prey species) control their mobility and thus their transfer to the next trophic level.…”