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Habitat patterns of subtropical and tropical planktic foraminifers in the Caribbean Sea were obtained from plankton samples collected in spring 2009 and 2013. The spatial distribution in surface waters (3.5 m water depth) and depth habitat patterns (surface to 400 m) of 33 species were compared with prevailing water-mass conditions (temperature, salinity, and chlorophyll-a concentration) and planktic foraminiferal test assemblages in surface sediments. Distribution patterns indicate a significant relationship with seawater temperature and trophic conditions. A reduction in standing stocks was observed close to the Orinoco River plume and in the Gulf of Paria, associated with high turbidity and concomitant low surface-water salinity. In contrast, a transient mesoscale patch of high chlorophyll concentration in the eastern Caribbean Sea was associated with higher standing stocks in near surface waters, including high abundances of Globigerinita glutinata and Neogloboquadrina dutertrei. Globorotalia truncatulinoides mainly lives close to the seasonal pycnocline and can be linked to winter conditions indicated by lower sea-surface temperatures (SSTs) of ∼20°C. Globigerinoides sacculifer and Globoturborotalita rubescens were associated with oligotrophic conditions in the pelagic Caribbean Sea during early spring and showed a synodic lunar reproduction cycle. The live assemblages in the water column from 2009 and 2013 were similar to those reported in earlier studies from the 1960s and 1990s and to assemblages of tests in the surface sediments. Minor differences in faunal proportions were attributed to seasonal variability and environmental differences at the local scale. An exception was the low relative abundance of Globigerinoides ruber in the Caribbean Sea in 2009 compared to surface sediment samples and plankton net samples collected in the 1960s and 1990s. Decreasing abundance of Gs. ruber white in the Caribbean Sea may be associated with increasing SSTs over past decades and changes in nutrient flux and primary production.

Benthic foraminiferal faunas from the shelf and upper continental slope of the Celtic Sea (NE Atlantic) show a rich variety of Trochamminidae species. We recognized 31 taxa, of which 18 could be determined to species level. These 18 species comprise about 9% of all species of the family Trochamminidae that are described from Recent sediments worldwide. For species determination and generic classification, we used existing taxonomic concepts and assessed their applicability. Besides the morphology of the test and internal structures, different apertural. features play a fundamental role in the systematic subdivision of the Trochamminidae. The position of the aperture controls the chamber arrangement and, therefore, the final shape of the test. However, we found no relationship between the apertural features and shape of the chambers as well as between apertural features and mode of life. Using apertural features for a sound taxonomic designation of our specimens proves difficult, because apertures are often obscured. Further, combined morphological and molecular-phylogenetic studies are required to constrain the taxonomic relevance of apertural characteristics.

Alexander Volker Altenbach was born in 1953 in Frankfurt/Main, Germany. Alex attended school in Konigstein/Taunus, where he passed his Abitur in 1974. He then studied Geology and Paleontology at Goethe University, Frankfurt. During an internship on an oil rig in Denmark, he first experienced a professional working environment and the adventures of hydrocarbon exploration in the North Sea. For his diploma thesis Alex worked on the stratigraphy and tectonics of the Sierra de Montgai, in the Pyrenees, Spain, under the supervision of Rolf Schroeder, Senckenberg Museum, Frankfurt/M. The subject comprised a genuine geological mapping exercise and biostratigraphic dating of the exposed formations. Stratigraphic ages were determined with the Mesozoic orbitoids and planktonic foraminifera in thin sections. Alex shared the long travels to Spain with his two companions Hans-Joachim Wallrabe-Adams (aka Kolli) and Peter Brinnel, enjoying an old “concha naranja” Volkswagen van, as well as field work in the spectacular scenery of the Sierra de Montsec, and living the Catalonian lifestyle. As late as 1993, the theme of Alex’s habilitation defense again was the geology of the Sierra de Montsec, for which he had kept his fascination (cf. Wallrabe-Adams et al., 2005). Being challenged by disentangling the complicated tectonic structure of the Sierra de Montgai, Alex learnt Fortran78 to produce a virtual Schmid net on the central university computer, visualizing different deformation styles of the different tectonic units. His early professional computer programming probably gave rise to his later endeavor in computing. Attracted by the developments in Marine Geosciences at Kiel University during the early 1980s, Alex joined the Micropaleontology Group of Gerhard Friedrich Lutze, and commenced …

The present study investigated the combined effects of ocean acidification, temperature, and salinity on growth and test degradation of Ammonia aomoriensis. This species is one of the dominant benthic foraminifera in near-coastal habitats of the southwestern Baltic Sea that can be particularly sensitive to changes in seawater carbonate chemistry. To assess potential responses to ocean acidification and climate change, we performed a fully crossed experiment involving three temperatures (8, 13, and 18uC), three salinities (15, 20, and 25) and four pCO2 levels (566, 1195, 2108, and 3843 matm) for six weeks. Our results highlight a sensitive response of A. aomoriensis to undersaturated seawater with respect to calcite. The specimens continued to grow and increase their test diameter in treatments with pCO2 ,1200 matm, when Vcalc .1. Growth rates declined when pCO2 exceeded 1200 matm (Vcalc ,1). A significant reduction in test diameter and number of tests due to dissolution was observed below a critical Vcalc of 0.5. Elevated temperature (18uC) led to increased Vcalc, larger test diameter, and lower test degradation. Maximal growth was observed at 18uC. No significant relationship was observed between salinity and test growth. Lowered and undersaturated Vcalc, which results from increasing pCO2 in bottom waters, may cause a significant future decline of the population density of A. aomoriensis in its natural environment. At the same time, this effect might be partially compensated by temperature rise due to global warming.

The pore-densities (PD) in the tests of 232 specimens of the shallow infaunal foraminiferal species Bolivina spissa from eight locations off the Peruvian continental margin were investigated and compared to different environmental factors as water-depth, temperature, bottom-water oxygen ([O2]BW) and nitrate concentrations ([NO3–]BW). There is a negative exponential PD-[O2]BW correlation, but at oxygen-concentrations >10 µmol/l PD approaches a constant value without any further correlation to [O2]BW. The PD-[NO3–]BW relationship is better constrained than that for PD-[O2]BW. We hypothesize that the pores in the tests of B. spissa largely reflect the intracellular nitrate, and to a smaller extent the oxygen respiration. We also compared PD and porosity (P) of two single B.spissa and B.seminuda specimens from the same habitat. The comparison showed that P is significantly higher in B.seminuda than in B. spissa indicating that B.seminuda is much better adapted to strong oxygen-depleted habitats than B.spissa.

Uvigerina peregrina Cushman 1923 and related taxa are extensively used for paleoceanographical studies. A high degree of inter- or intra-specific variability leaves the status of these species unclear and has hampered sound paleoenvironmental interpretations to date. The species concept and diagnostic features of Uvigerina peregrina and the closely related Uvigerina pigmea d’Orbigny 1826, Uvigerina peregrina parva Lutze 1986 are re-assessed in this paper. Uvigerina sp. 221 Lutze 1986 is formally described and named Uvigerina celtica n. sp. The overall size of the tests, the length/width ratio, and the morphology of costae are considered key diagnostic features while the presence or absence of spines is of minor importance for species characterization. Geographic and depth distributions of living Uvigerina taxa are described using faunal census data from the northwest African and western European continental shelf and slope from the 2 ° S to 70 ° N, and from the Caribbean. The regional distribution and inferred population dynamics reveal that Uvigerina peregrina, Uvigerina celtica n. sp. and Uvigerina pigmea are indeed different species. Uvigerina peregrina parva is most likely a subspecies of Uvigerina peregrina and not an ecophenotype.

The depth distribution of living (Rose Bengal-stained) benthic foraminifera in near-surface sediments was analyzed along 4 short cores from the western Iberian Margin and Gulf of Cadiz at water depths from 800 to 1920 m. Pore-water oxygen, Chloroplastic Pigment Equivalent (CPE), and total organic carbon (C org ) concentrations were measured in the same or adjacent cores. These values were used to constrain the limiting oxygen and nutrient levels that defined the ranges in sediment depth and abundance maxima of foraminiferal species. The population density showed a good correlation with pore-water oxygenation indicating that oxygen is a limiting factor for endobenthic foraminiferal assemblages at mid-depths between 800 and 1200 m. At the deep-water site, however, the fauna appeared nutrient limited. More than half of the benthic species occupied extended sediment depth habitats and a wide range of oxygen levels among the sites studied. Thirty-nine of 103 species occurred in two or more cores and showed distinct abundance maxima, 36 in the uppermost 2.0 cm where the CPE concentrations were high. Living foraminifers were not found at depths where the CPE-values were lower than 0.1 μg/g. This level indicates trophic conditions critical for the survival of endobenthic species. The frequency distribution of the lower oxygen range limits of all species showed maxima at the high oxic/low oxic (3 ml/l), low oxic/suboxic (1.5 ml/l), and suboxic/dysoxic (0.3 ml/l) boundaries and thus depicted the ecological significance of these previously recognized ecolimits. Only 30 % of the species display consistent patterns in relation to pore water oxygen. Dysoxic indicators were Globobulimina affinis, Chilostomella ovoidea and Bathysiphon capillare. Many species previously designated as suboxic indicators were ubiquitous or preferred microhabitats at oxic levels. Boundary conditions for the dysoxic indicator G. affinis were pelagic flux rates higher than 3.5 g C m −2 yr −1 , a habitat depth below the homogeneously bioturbated layer in areas outside of high productivity zones, and CPE concentrations of 0.1 to 1.0, preferentially 0.7 to 0.8 μg/g. The distribution pattern suggested that G. affinis thrives mainly on dysoxic bacteria and actively seeks this nutrient resource.