ALBERT

Description: The planktonic foraminifer Globigerinoides sacculifer (Brady) was cultured under two different light intensities and in continuous darkness. High light intensity (HLI = 4oo-soo einsteins/m2/s) resulted in a longer lifespan, a greater number of chambers formed, and a larger final shell size compared with individuals cultured under low light intensity (LLI = 20-50 einsteins/m2/s) or in continuous darkness. Shell growth rates were unaffected by increasing light intensity, but gametogenesis was delayed. Continuous darkness induced a rapid onset of gametogenesis in organisms with shell lengths larger than 250 m. Feeding frequency had a greater effect on growth and reproduction than light intensity under conditions of LLI and HLI, but continuous darkness had an overriding effect on growth and reproduction owing to the rapid onset of gametogenesis which terminated the life of the mother cell. Our previous data indicated that the longevity of G. sacculifer was dependent on feeding frequency, and that G. sacculifer cultured under LLI had a lifespan of approximately 2-4 weeks. Present results suggest that the lifespan can vary from a minimum of 8 days for organisms fed daily in continuous darkness to a maximum of 54 days for organisms fed once every 7 days and maintained in HLI. It is concluded that individual G. sacculifer attain a shell size greater than 6oo ,urn only if they maintain their position in the euphotic zone. Prolonged existence below the euphotic zone would result in premature death or gametogenesis following stunted shell growth.

Description: 122 regurgitations by adults and chicks of the small grey-headed and black-browed albatrosses (mollymauks) included, besides flesh remains, 421 upper beaks (mandibles) and 422 lower beaks of cephalopods. The lower beaks and some flesh remains were identified, their lower rostral lengths were measured and the wet weight of squids represented by beaks was estimated. Nine species of squid and one octopod were identified. In both species of albatross, the muscular ommastrephid squid Todarodes is the principal squid in the diet, contributing 88% of the beaks and an estimated 91% of the weight of cephalopods represented by beaks in grey-headed albatrosses and 68% of the beaks and 76% of the weight in black-browed albatrosses. Second in importance in the diet is a cranchiid Mesonychoteuthis sp. A, which contributes 8% and 25% by number and 4% and 12% by weight to the diet of grey-headed and blackbrowed albatrosses, respectively. The eight remaining species are each represented by either one or two lower beaks. These samples are compared with samples from sperm whale stomachs and wandering albatrosses also collected near South Georgia.

Description: Symbiotic luminous bacteria have been described in, and cultured from, a number of species offish and cephalopod. Indeed only in these two groups are extracellular luminous bacteria believed to be utilized as a source of light (see Buchner (1965) and Herring (1978) for references). Despite several earlier investigations of such symbioses in cephalopods the bacteria in these animals have not been adequately identified, nor has the extent of their role been clarified. The ultrastructural relationships between bacteria and the tissues of the squid accessory nidamental gland have been investigated in the non-luminous species Loligo pealei (Lesueur) (Bloodgood, 1977) and Sepia officinalis L. (Van den Branden et al. 1979) but no comparative work on luminous species has been undertaken apart from that on Heteroteuthis dispar (Rüppell), whose photophore does not contain typical luminous bacteria (Dilly & Herring, 1978; cf. Leisman, Cohn & Nealson, 1980). The order Sepioidea contains five families, among which are the two families Sepiolidae and Spirulidae. Though the presence of luminous bacteria is known in some sepiolids (as well as in certain loliginids (order Teuthoidea)) some doubt remains about the source of light in the photophore of Spirula spirula Hoyle. The steady luminescence of this species has prompted speculation that bacteria may be involved (Harvey, 1952). In this paper we compare the anatomy and ultrastructure of the photophores of both Sepiola and Spirula in order to clarify some of these problems.

Description: Regurgitations of the chicks of wandering albatrosses near their nests included 762 upper beaks (mandibles) and 532 lower beaks of cephalopods. Twenty-five species of cephalopod are present in the diet. Analysis of the complete samples shows the three most important species in the diet to be Kondakovia longimana (40.0% by number), Taonius pavo (16.9%) and Histioteuthis(?) eltaninae (8.7%). While the large Taningia danae only comprises 1.3% by number, it may contribute over 5% by weight. The species and size ranges of beaks are compared with those occurring in the stomachs of sperm whales killed by whalers in the Southern Hemisphere (Clarke, 1980). The ten complete samples contain an average of 44 beaks which probably represents about 200 days' accumulation. Both Antarctic and warm-water cephalopods are present in the diet. These albatrosses possibly scavenge some of thei food from vomit of sperm whales.

Description: Three arrays of ocean bottom seismographs have been deployed to study the seismicity at the northern end of the Juan de Fuca ridge system off western Canada. Nearly 100 events were located with estimated accuracies generally better than ±10 km, all lying on or near the en echalon ridge-transform fault plate boundaries as defined in this area by the magnetic anomalies, the seafloor morphology and by other geophysical data. The depths of 12 events were determined to lie between 2 and 6 km below the top of the crust. The seismograms exhibit clear P and S wave arrivals along with phases that involve P to S and sometimes S to P conversion probably at the base of the sediments beneath the instruments. The event magnitudes have been estimated from signal duration using four calibration events that were well recorded by a land station. The magnitude estimates permit the determination of rough magnitude-frequency of occurrence relations over the magnitude range of 1 to 3 that are in surprisingly good agreement with the recurrence relations for the area at larger magnitudes from 75 years of land station data. The mean P wave velocity in the uppermost mantle from the earthquake data recorded by the sea floor arrays is 7.6 km s-1 and the mean Vp/Vs ratio is 1.71 or a Poisson's ratio of 0.24.