Fluoride in Antarctic Krill (Euphausia superba) and Atlantic Krill (Meganyctiphanes norvegica)

Abstract

Samples of Antarctic krill (Euphausia superba) and Atlantic krill (Meganyctiphanes norvegica) were analysed for fluoride using a selective fluoride electrode method. Both species showed very high concentrations, a total of 1330–2400 mg F−/kg on fat free dry weight basis in raw samples whereas deep sea prawns (Pandalus borealis) showed a total of 18–91 and red feed (Calanus finmarchicus) 10–37 mg F−/kg. Sections of Antarctic krill were analyzed, and the highest concentration was found in the carapace, 4260 mg F−/kg fat free dry matter, compared with 570 and 750 mg F−/kg in raw and boiled muscle. Biological availability was measured in a chick assay, and showed fluoride in krill to be equally utilized as sodium fluoride added to the diet. Key words: krill, red feed, deep sea prawn, fluoride

Physiology and Metabolism of Northern Krill (Meganyctiphanes norvegica Sars)

“…Fluorides derive principally from the weathering of fluoride minerals and volcanic activity although a small proportion is contributed by the use of aerosols. The fluoride content of Northern krill, in agreement with what is known of other euphausiids, is quite high compared to other oceanic invertebrates with whole body burdens of 2360 mg F À g À 1 dry weight (DW) (Soevik and Braekkan, 1979) and 2153 mg F À g À 1 DW (Adelung et al, 1987). Adelung et al (1987) showed that most of the fluoride was incorporated into the exoskeleton (3343 mg F À g À 1 DW), with relatively small amounts found in the tissues (e.g.…”

Evaluation of krill (Euphausia superba) meal as a partial replacement for fish meal in rainbow trout (Oncorhynchus mykiss) diets

“…*Not detectable (ND). Krill contains a high amount of fluoride mainly derived from the exoskeleton (Soevik and Braekkan, 1979;Schneppenheim, 1980;Adelung et al, 1987;Sands et al, 1998). Grave (1981) investigated the uptake of fluoride from Antarctic krill by salmonids in brackish water for up to 3 years.…”

The fin whale, a marine top consumer, exposes strengths and weaknesses of the use of fluoride as ecological tracer

“…In our study the krill collected from the stomach of the whales was partially digested, so neither the molting state nor the species composition could be established. However, previous studies have shown that the diet of North Atlantic fin whales is mainly composed of M. norvegica in both areas (Soevik and Braekkan, 1979;Aguilar 1985;Sigurjónsson and Víkingsson, 1997), and the difference between areas was found to be so large that within-areas variation was considered not able to obscure it. Thus, concentrations of fluoride were significantly higher in the krill from W Iceland than in that from NW Spain.…”

“…Soevik and Braekkan (1979) found levels of fluoride in the range 1330-2400 mg kg À1 fat free dry weight in whole body of North Atlantic Meganyctiphanes norvegica and Antarctic Euphausia superba, and Sands et al (1998) reported levels of up to 5977 mg kg À1 dry weight in the exoskeleton of Antarctic Euphausia crystallorophias and of 12800 mg kg À1 dry weight in the mouth parts of Antarctic E. superba. Consistently with these high levels in krill, most vertebrates feeding on these krill, such as Adélie penguins (Pygoscelis adeliae), crabeater seals (Lobodon carcinophagus), minke whales (Balaenoptera acutorostrata) and fin whales (Balaenoptera physalus), also show high fluoride content in their bones and other skeletal structures (Schneppenheim, 1980;Adelung et al, 1985;Walton, 1988;Landy et al, 1991;Alne, 1995).…”

“…Krill, which was assumed to reflect fluoride background levels, presented high variability of fluoride concentrations within each location. In Euphausiids, fluoride is mostly deposited in the exoskeleton, where it might play a role as a hardener (Soevik and Braekkan, 1979;Adelung et al, 1987;Sands et al, 1998). However, the exoskeleton is discarded in each molt and fluoride is therefore lost to be re-accumulated from the environment when the new exoskeleton is built.…”