No abstract

The oxygen and carbon isotopic compositions of the planktonic foraminifer, Neogloboquadrina pachyderma (sinistral), were determined at 20-cm intervals through the "composite" top ~ 22 m of sediments at ODP Site 645 (Holes 645B, 645C, 645F, and 645G) and at 10-cm intervals through a 9-m piston core (85-027-016) collected during the Hudson site survey. Quantitative analyses of palynomorphs, notably dinocysts, and of planktonic foraminifers were performed. Organic and nitrogen contents and isotopic composition of nitrogen and carbon in organic matter also were determined. These data provide a high-resolution record of changes that occurred in surface-water masses during the last glacial cycle in Baffin Bay. The basin experienced low planktonic productivity during most of the late Pleistocene, either from dilution in surface water by meltwater discharges from the surrounding ice-sheet or from the presence of a relatively dense sea-ice cover. Peaks of meltwater discharge are indicated by S 18 0 values as low as about 1.5%o, correlative S 13 C-5 18 0 shifts, low concentration of planktonic foraminifers, high concentrations of glacially reworked pre-Quaternary palynomorphs, and low-salinity dinocyst assemblages. As a whole, 5 18 0 values ranging between 4.5 and 2.5%o allow the establishment of an 18 0 stratigraphy spanning isotopic stages 5 to 1. Because of the poor core recovery, the general paucity of microflora and microfauna, and the possible occurrence of slumping or debris flow at Site 645, further interpretation remains problematic.

Laboratory cultured amphipods, Amphithoe valida, were exposed to the water soluble fractions (WSF) of a No. 2 fuel oil for 6 days, and then transferred to clean sea water for one week. Survival and nesting behavior were observed daily, and the lipid contents were checked at the end of exposure and at the end of depuration. Survival of amphipods during exposure was high at all concentrations of W S F tested (0 to 25%). A delayed toxicity was observed; mortality was high in concentrations /> 15% WSF during depuration. The number of nests decreased with increasing concentration of WSF and length of exposure. Recovery of nest building activity in clean sea water was either lacking or small, indicating some damage to their nesting capability. The lipid contents of amphipods were close to the expected range (except at 25~ WSF) following the exposure, but dropped to about 1% following recovery compared with an expected value of 3.3%. Impairments of the chemosensory and locomotory systems may occur during exposure, which prevent amphipods from constructing nests for protection and food reserves, and eventually lead animals to use their stored energy of lipid for survival. Of the three biological parameters studied, nesting behavior and lipid content as a percentage of dry weight were better indicators of the sublethal stress of WSF than the response of survival; significant alterations of the former two parameters were found at the concentrations /> 5% WSF.Water, Air, and Soil Pollution 15 (1981) 185-195.

No abstract

The occurrence in sediments of chlorophyll-derived tetrapyrroles provides evidence for primary photosynthetic communities in palaeo water columns. In ancient sedimentary rocks the components occur mainly as nickel or vanadyl complexes of alkyl porphyrins, and to a lesser extent carboxylic acids. Although extensive loss of functional groups has occurred, the structures of a number of the components reveal that chlorophyll carbon skeletons can survive intact or virtually intact, although in other cases the skeletons have been modified by rearrangement. The structures of a few components indicate an origin from the chlorophylls c , and thus an algal input, whereas an origin from photosynthetic bacterial chlorophylls is apparent from the carbon skeletons of other components. Such studies, taken with other distributional features (e.g. ratio of nickel to vanadyl components, extent of tetrapyrrole preservation) can provide information about the productivity and preservation of organic matter and presence of water column anoxia at the time of deposition. Studies of the tetrapyrrole components in one recent and two highly immature older sediments have provided further evidence for the pathway of defunctionalization, through the identification of the minimum number of components necessary to link a chlorophyll, such as chlorophyll a , to the major alkyl porphyrin in sedimentary organic matter. Additionally, evidence for an early and unexpected transformation pathway comes from the recent identification in sediments of chlorin acids esterified with sterols.