ISSN:
1432-1793
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The elimination of 3 radionuclides from Euphausia pacifica was measured over a 5 month period. The biological half-lives for 65Zn, 137Cs, and 144Ce, calculated after the euphausiids had ingested radioactive Artemia nauplii, were found to be 140 days, 6 days, and 7.5 h, respectively. The percentages of body burdens lost in molts were greatest for the fission products, 144Ce (21%) and 137Cs (7%), and least for 65Zn (1%). Elimination of the isotopes in the feces could not be followed because of the difficulty in collecting fecal material for analysis; however, 1 sample collected 2 months after the beginning of the elimination experiment had no measurable radioactivity. Loss of 65Zn from molts and time to disintegration of the molts were found to be temperature dependent over a 5° to 15°C range, and the sinking rate of molts was both temperature and salinity dependent. Calculations showed that, in areas in the North Pacific outside the influence of upwelling, percentage 65Zn loss from sinking molts (before disintegration of the molts) was likely to be the same throughout the year, since the molts would be exposed to about the same mean temperature in the water column in all seasons. Even though temperature structure in the upper layers changes with season, mean temperatures change very little when calculated over the sinking distance of intact molts. Intact molts would sink to slightly over 400 m in the absence of turbulence, and would lose 87% of their 65Zn by the time they reached this depth. Sinking molts thus might contribute substantially to the vertical transport of 65Zn in the sea. If loss of 65Zn in fecal pellets is assumed to be small under our experimental conditions, and molting loss is only 1% of 65Zn body burden, the major mechanism of 65Zn loss from euphausiids feeding on non-radioactive food must be isotopic exchange with the water. Approximately 96% of the initial body burden was eliminated over a period of 5 months.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00355220
