Vertical distribution and feeding patterns of midwater fish in the central equatorial Atlantic II. Sternoptychidae

The vertical distribution of seven sternoptychid species was examined from RMT 1+8 samples collected aboard R. V. Meteor in March-April 1979 and from Royal Research Ship R.R.S. Discovery in July 1974 in the central equatorial Atlantic. During daytime sternoptychids occupied depths between 200 and 1250 m, with Sternoptyx pseudobscura living deepest, centering between 800 and 900 m, and Argyropelecus sladeni most shallow, aggregating predominantly at 300 and 400 m. They are all considered limited or partial migrants, ascending only some 100 and 200 m towards the surface at night. Only A. sladeni was observed to enter the epipelagic zone (0 and 200 m).-Feeding patterns were investigated from stomach content analyses of Sternoptyx diaphana, S. pseudobscura, Argyropelecus sladeni and A. affinis. Additional stomach contents were analysed from samples of S. diaphana, A. hemigymnus and A. olfersi collected in June 1985 from F.R.V. Walther Herwig in the temperate NE Atlantic at 46°N, 17°W by means of the Engel Trawl. The food spectrum of the six species is generally described, and additional dietary evidence regarding calanoid copepod prey is provided for four of these taxa. All sternoptychid species investigated were planktivorous, feeding predominantly on copepods and ostracods, except for the largest size class, which preyed heavily on euphausiids and amphipods. The relationship of predator size towards prey type and prey size is analysed for both Sternoptyx species. Of these, S. pseudobscura in particular exhibits taxonomic selectivity towards polychaete prey. The diet of both species of Sternoptyx included a number of epipelagic or even neustonic calanoid copepod species which contributed more than 50% of the total copepod population by numbers. So far it is not known how the predators find access to prey organisms of the upper 200 m, as netfeeding is considered unlikely. Cyclopoid copepods of the genus Sapphirina were observed as dietary component particular of S. diaphana.     

Determining the carbon-to-chlorophyll ratio of natural phytoplankton

For field samples, regression analyses of plots of chemically determined particulate organic carbon on chlorophyll are often employed to estimate the algal carbon-to-chlorophyll ratio (F) in the presence of appreciable amounts of nonalgal particulate organic carbon. Spurious results will be obtained, however, if the temporal rate of change of the algae or the nonplant matter reverses its sign during the sampling interval and the samples cannot be ordered correctly in time or space. Previously recognized sources of bias inherent in the chemical approach are also discussed. The great uncertainty of our present knowledge of F is pointed out. It is shown that the concentration of microscopically visible, nonliving particles in the sea isnot known. Renewed studies are suggested as a means of improving on the chemical approach to determining F. The general argument holds for the ratios of nitrogen (particle volume, etc.)-to-chlorophyll, carbon (nitrogen, particle volume, etc.)-to-ATP, and similar conversion factors.Contribution No. 932 from the Department of Oceanography, University of Washington, Seattle, Washington 98195, USA. The article is a revised and expanded version of a paper contributed at the Joint Oceanographic Assembly, September 1976, at Edinburgh, Scotland, UK.     

A ten-year study of chlorinated hydrocarbon insecticide residues in bovine milk in Illinois, 1972 - 1981

Milk supplies in Illinois were monitored for chlorinated hydrocarbon insecticide residues from 1972 through 1981. The percentage of milk samples that were contaminated with aldrin/dieldrin, DDT and its analogs, and BHC/lindane decreased during the 10-year sampling period. The percentage of samples contaminated with aldrin/dieldrin decreased from 98.7% in 1978 to 5.9% in 1981. The amount of aldrin/dieldrin residues found in contaminated samples also decreased from an average of 0.077 ppm (1972-79) to 0.001 ppm in 1980-81. The levels of chlordane and heptachlor/heptachlor epoxide residues in milk did not decrease, but residues of BHC and DDT decreased gradually over the 10-year period. The percentage of samples that had less than 0.1 ppm of all chlorinated hydrocarbon residues combined ranged from 10.6% to 25.7% during 1972 through 1978 and increased to 36.2% in 1979, 71.1% in 1980, and 61.4% in 1981.     

The effects of ethylene chlorohydrin on fatty acid synthesis

Male chicks weighing 700 to 900 g. received an acute or eight doses IG of 60 or 40 mg/kg ethylene chlorohydrin (ECH) respectively and were sacrificed eighteen hours after the last dose. Mitochondrial elongation of fatty acids was decreased significantly while fatty acid synthetase activity was not significantly affected by ECH treatment. Cytochrome c oxidase activity in fresh whole liver homogenate was significantly higher in chicks subjected to acute exposure with ECH when compared to the controls. Upon freezing and thawing of homogenates, cytochrome c oxidase activity increased significantly in the control group but was unchanged in the ECH group which suggests that the mitochondrial membrane integrity is compromised by the ECH treatment. Serum and liver triglyceride levels were significantly elevated in both the single and multiple ECH dose groups. Liver to body weight ratios were significantly higher in both treatment groups when compared to their controls. Histological examination of the liver of ECH-treated chicks showed cytoplasmic clearing of the cells but no vacuolization or centrilobular necrosis. Serum isocitrate dehydrogenase levels were significantly higher in the multiple treatment ECH group than in the control group.     

Dieldrin, heptachlor, and chlordane residues in soybeans in Illinois 1974, 1980

The Illinois soybean crop was monitored in 1974 and 1980 for dieldrin, heptachlor, and chlordane residues resulting from the use of these compounds for corn soil insect control in the years before extensive soybean cultivation. Residue levels were compared with past published amounts. Dieldrin residue levels in soybeans declined between 1974 and 1980. Heptachlor and heptachlor epoxide levels remained level between 1974 and 1980. Chlorinated hydrocarbon residues were lower in the southern third of Illinois than for the remainder of the state.     

Statistical assessment of subsampling procedures

As shown by the examples in this paper, the concentrations in subsamples are not necessarily independently and normally distributed despite vigorous grinding and mixing of the original sample. Studies of the statistical properties of subsample concentrations should test for deviations from independence and normality and, if deviations are found, should model the observed distribution. The tests include an analysis of variance to check for less variation among nearby subsamples than among widely spaced subsamples, as well as the computation of the probability plot correlation coefficient to check for nonnormality. These tests are illustrated with ${}^{239}\text{Pu}\text{+}{}^{240}\text{Pu}$ measurements on subsamples prepared for use as standard reference materials. These materials are used in quality assurance for environmental radioactivity measurements. The material consisting of Human Liver (SRM 4352) exhibits dependence, which may be due to inadequate mixing or to later handling that caused segregation. The material consisting of Human Lung (SRM 4351) and the material consisting of soil from Rocky Flats (SRM 4353) exhibit nonnormality due to the particulate nature of some plutonium-bearing fractions of the material. The lung measurements are modeled with the gamma distribution. The soil measurements are modeled with a combination of the normal distribution and a distribution that models the occurrence of outliers. The use of these models to describe the subsamples involves assessment of the contribution of the measurement error.