ALBERT

Description: Prior to this work, the planktic foraminiferal genus Beella Banner and Blow (1960) has never been described from Pleistocene sediments from the Norwegian-Greenland Sea (NGS). The general characteristics of this species agree well with the most recent emendation of the genus Beella. Accordingly, the described species is considered to be Beella megastoma (Earöamd). Test sizes range from 200-700 μm, but specimens are mainly confined to the 250-500 μm mesh-size fraction. Interpretations of stable isotopes, sedimentological, and other micropaleontological data indicate that this species is not simply a "warm-water form" and, despite its low abundances, it is a species of major paleoceanographic significance. Stratigraphically, it is confined to meltwater events of Termination II, III, and VI (oxygen isotopic stage boundary 5/6, 7/8, and 15/16) and not to the ensuing interglacial maximum. Hence, these "Beella-events" represent a particular oceanographic phenomenon and are designated in accordance with the present numerical system of deglacial terminations as Event B2, B3, and B6 respectively.

Description: The presence of true ponticuli and very deep inter locular spaces receiving secondary lamination in Virgulinella pertusa (Reuss, 1861), the type species of Virgulinella, poses problems for its classification. Comparing these features with results and proposals made for the elphidiid taxa, the separate superfamily Virgulinellacea is proposed. The Virgulinellacea are seen as an isolated evolutionary experiment, probably originating in the Buliminacea.

Description: Analysis of benthic foraminifera in two short sediment cores (15 and 53 m water depth) from heavy metalpolluted Sttrfjord indicates that a faunal shift has taken place, due to heavy metal enrichment. Both cores reveal an upward transition from a moderately polluted environment represented by a Verneuilina media assemblage to an extremely polluted environment represented by an Eggerelloides scabrus assemblage. This faunal change may result from an increased competitiveness of some shallow water species in deeper water areas exposed to environmental stress, at the expense of more normal marine forms which have stricter ecological requirements. The total abundance of foraminifera d,ecreases upward in both cores, whereas species diversity shows ouly a minor decrease. The frequent occurrence of abnormal and pyritized specimens is attributed to the effects of pollution, and seven different modes of test deformation are described.

Description: Ontogeny is an important source of variability in morphology and stable-isotopic composition in planktonic foraminifera. Through careful morphological analysis the populations of Globorotalia menardii and G. tumida were studied in detail at a single locality, the Ceara Rise. The foraminiferal test is dominated by two process of growth: the accretion of chambers and the formation of an enveloping calcite crust. These are recognized through measurements of shell size, shape, and density. The populations are divided into groups according to their stage of chamber and crust development. For both Globorotalia menardii and G. tumida the measured isotopic composition of whole specimens indicates that the organisms grow in the upper 50 m of the water. The crust is emplaced at depths of between 50 and 100 m, assuming that the shell is precipitated in isotopic equilibrium with seawater o18O. Assuming the smaller specimens lacking the crust represent the early stages of larger crusted specimens, one can calculate the oxygen- and carbon-asotopac compositions of the calcite added by the two processes. Crust composition in Globorotalia tumida appears to be in equilibrium with seawater o180. In G. menardii the crust is lighter in o13C than the equilibrium values. Similar measures of isotopic composition from the Sierra Leone Rise and the Bermuda Rise support these findings. At the Bermuda Rise, the isotopic data suggest growth in shallow water during the summer months, when a seasonal thermocline is well developed. Assuming these species require a shallow pycnocline to thrive, a decrease in deep-water upwelling during lacial time could deepen the pycnocline, which would explain their absence from North Atlantic sediments of that age.

Description: Members of the genus Bolboforma are marine microfossils of generally spheroidal shape, whose tests are composed of monocrystalline low-magnesium calcite, and are believed to be derived from protophytic algae. Bolboformids have been studied primarily in sediments from the North Atlantic, the North Sea Basin, and southern high latitudes; they range in age from middle Eocene to early Pliocene. They have not been observed in Pleistocene to Recent sediments. The geographical distribution of the genus and the stratigraphic occurrence of 42 Bolboforma taxa are outlined herein. Thirteen biozones are defined. Bolboformids, as now known, are distributed mainly in high latitudes. So far, occurrences in low latitudes are rare. These microfossils have considerable biostratigraphic value, mainly in high latitudes, where they supplement the standard zonations based on other microfossil groups. This paper includes monographic, uniform descriptions of all known Bolboforma taxa. New species are Bolboforma atlantica, B. bella, B. compressibadenensis, B. compressispinosa, B. furcata, B. geomaris, B. indistincta, B. latdorfensis, B. micra, B. pustula, B. pentaspinosa, B. praespinosa, B. robusta, B. subfragoris, and B. subreticulata. Four taxa are left in open nomenclature.

Description: The biological response to extreme temperatures and salinities is investigated in the laboratory for seven species of planktonic foraminifera: Globigerinoides sacculi/er (Brady), Globigerinoides ruber (d'Orbigny), Globigerinoides conglobatus (Brady), Globigerine/la siphonifera (d'Orbigny), Orbulina universa d'Orbigny, Neogloboquadrina dutertrei (d'Orbigny) and Globorotalia menardii (d'Orbigny). When one of the vital processes, food acceptance, growth or reproduction is inhibited by a culture variable, the absolute survival limit is reached. The measured in vitro temperature ranges compare well with the global temperature distribution patterns of these species, suggesting that this parameter plays a major role in their biogeographical distribution. The salinity ranges that are tolerated in laboratory cultures exceed the range encountered in modern oceans. Thus salinity does not limit the distribution of the species investigated herein. In general, larger mean final shell sizes are attained and the total shell length increase is larger at optimum temperatures and salinities than at extreme culture conditions, but the differences were not always statistically significant. Marginal temperature and salinity conditions do not induce contained growth in expatriated specimens. Under extreme culture conditions, the relative frequency of the different shell morphologies is altered relative to normal conditions. "Abnormal" phenotypes are more frequent under normal conditions and the "normal" morphology is found more often under extreme conditions. As opposed to previous reports, the frequency of kummerform chambers generally decreases toward extreme temperature and salinity culture conditions, indicating that kummerform phenotypes are not indicative of environmental stress. The incidence of sac-like chambers in G. sacculi/er and the formation of spherical chambers in adult 0. universa decrease toward extreme temperature and salinity culture conditions, demonstrating that maturation is suppressed in stress situations. SEM investigations show that changes in shell porosity are correlated with treatment variables in culture. The highest porosities are attained at higher temperatures and lower salinities. Generally, an increase in total porosity is achieved by an increase of the pore area accompanied by a reduction of the pore density. The in vitro experiments explain the changes that occurred in the Pleistocene foraminiferal assemblages from the Red Sea around 18 thousand years ago and earlier. During glacial periods, salinity approximated or even exceeded the upper thresholds that were tolerated under laboratory conditions. Under these circumstances, species disappeared from the water column. The order of disappearance as recorded in the sediments may be explained with the upper salinity limits found in this study. Also, the recurrent shifts of dominance between G. sacculi/er and G. ruber are well documented for this fossil assemblage. The present experiments support the conclusion that salinity is the driving mechanism behind this phenomenon. Observations in modern oceans suggest that the fertility of the water mass is probably also an important factor behind the shifts of dominance between G. sacculi/er and G. ruber.

Description: The restudy of Buliminoides species leads to the redefinition of both the genus and the family Buliminoididae. Buliminoides differs from buliminid taxa in lacking a toothplate, possessing discoidal chambers not arranged in a trochospiral, and in having a unique apertural face. The genus bears no relation to Glabratella, since their respective apertural faces are not equivalent. A lectotype is designated for Buliminoides williamsonianus; Buliminoides bantamensis is refigured, the holotype having perished; and Buliminella choctawensis is tentatively reclassified in Buliminoides.

Description: Foraminiferal evidence from the eastern equatorial Pacific and from the North Atlantic indicates that the dissolution of deep-sea carbonates was intensified during interglacials rather than during glacials, in contrast to widespread opinion. Pleistoccne dissolution cycles introduce a systematic bias into the Interpretation of calcareous fossil assemblages near and below the lysocline zone.

Description: Three closely related species ( A. beccarii (Linn.), A. batava (Hofker) and A. tepida (Cushman) have been studied. Each possesses a multilaminate “chitinoid” endoskeleton, the outermost lamina possessing imperforate pustulae of shape characteristic for the species. The pustulae are fused to segmented tubules of organically-bound carbonate granules; these tubules line the canaliculi linking the inner and outer perforations of the test wall, and differ only in length between the three species. The calcareous wall is essentially granular in internal morphology, and is built upon an organic framework in which the tubules play a significant part. The apertural structures are described, and it is confirmed that the toothplate is structurally continuous with the septal (“rotalid”) flap and the basal calcareous lamella of the test. The distribution of intrathalamous and extrathalamous cytoplasm in A. tepida is described, and the first sequential photographs of cytoplasmic extrusion are presented for Ammonia. The relationship between the organic skeleton, the calcareous exo- and endo-skeletons, and the cell, is discussed.

Description: Morphological characters, interrelations, evolutionary trends, synonymies, Stratigraphie and paleogeographic distribution of 15 species here included in Globigerinatheka are discussed and illustrated by line drawings and SEM mircographs. In order to stress their interrelations, all taxa—with the exception of G. semiinvoluta—are given subspecific rank in a trinomial System. Holotypes and some additional types of the taxa discussed, which originally were published at widely varying magnifications, are reproduced at a uniform scale to facilitate their comparison. By this procedure alone the four species subconglobata, indes, mexicana and semiinvoluta become clearly distinct. The final chamber/bulla problem, of some importance in the genus, is discussed and illustrated. Evidence is given that G. semiinvoluta is a valid species, and not a synonym of G. mexicana mexicana. Its variability is demonstrated by a series of SEM micrographs. One subspecies, G. subconglobata luterbacheri, is described as new.

Description: Planktonic foraminifera were collected from an oceanic front off Baja California, Mexico, during April and May, 1965, in connection with studies of the physical oceanography of the front. Four major water masses were present: Southern Surface Water at approximately 0-50 m, Northern Surface Water, forming a submerged intermediate layer between about 150-50 m, Southern Deep Water below 150 m, and Northern Deep Water deeper than 250 m. Planktonic organisms smaller than 2 mm were concentrated in the surface waters, suggesting that food for foraminifera was most abundant there. Organisms larger than 2 mm, considered a measure of potential predators of foraminifera, were abundant in both surface and intermediate waters. Most foraminiferal concentrations were from 1 to 100 specimens per m :J, with the largest concentrations in Southern Surface Water above the front and in deep water along the front. Lowest concentrations were in intermediate water, except in the frontal mixing zone, and at depths below 450 m. Empty shell concentrations were about one-tenth of associated living concentrations. Possible errors of concentration estimates were assessed by comparing paired net and paired tow results. Seventy percent of these estimates appear to be precise within a factor of 1.3. The error introduced by patchiness probably is much larger. Four foraminiferal assemblages are recognized: ( 1 ) Southern Surface Water assemblage, (2) widespread species with southern affinity which apparently tolerate the intermediate water, ( 3) species brought in with the submerged northern water, and ( 4) the assemblage inhabiting the deep waters. The estimated average minimum flux of empty shells was approximately 6% of the living standing crop I day by volume. The relative empty shell output was greater than this for many intermediate water species, and less for species restricted to southern and to deep water. The intermediate layer contributed approximately one-half of the empty shell flux, where specimens with small terminal chambers (kummerforms) were abundant. The sediment produced in the front contained about 50% kummerforms, but the total standing crop of living foraminifera contained only about 10%. The tongue of advected intermediate water may have represented an unfavorable habitat for foraminifera, where northern species were submerged and possibly deprived of food or otherwise impeded in their normal growth. Southern species also may have been displaced from their normal habitat by mixing processes. These displacements are suggested as one cause for the formation of small terminal chambers in specimens inhabiting intermediate depths. Empty shells apparently arise through reproduction, stress from displacement, and predation, with predation being the least important mechanism.

Description: The foraminifer Rosulina globularis d'Orbigny from natural and laboratory populations is occasionally preyed upon by free-living, marine nematodes. Borings 3.7 to 14.3 in diameter in the tests of living and dead specimens of R. globularis and dead specimens of Eolivina doniezi Cushman and Wickenden from the same natural and laboratory populations are attributed to the predaceous nematodes. Predation in the laboratory populations is greater than in the natural populations, especially among juvenile specimens of R. globuluris. Borings in R. globuluris occur characteristically in the outer whorl, whereas, those in B. doniezi are generally confined to the apertural half of the test. This preference for the area of wall penetration is thought to correspond to the accessibility or living position of the prey. However, several incomplete borings coincide with test pores, and thus represent test penetration in an area of least resistance. Identical borings occur in Holocene and Cretaceous bathyal and neritic foraminifers. Another kind of borings in these specimens, while in part resembling gastropod boreholes, may likewise be due to soft-bodied organisms. Evidence of predation provides ecologic and paleoecologic information on the living habits, habitat, and community structure of the foraminiferal prey, and can directly influence the interpretation of foraminiferal production and rates of sedimentation based on foraminiferal production.