scholarly journals Factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern North Atlantic

2016 ◽  
Author(s):  
Andreia Rebotim ◽  
Antje H. L. Voelker ◽  
Lukas Jonkers ◽  
Joanna J. Waniek ◽  
Helge Meggers ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Mixed Layer ◽  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Depth Interval ◽  
Individual Species ◽  
Habitat Depth ◽  
Chlorophyll A Concentration ◽  
Eastern North Atlantic ◽  
Species Specific

Abstract. Planktonic foraminifera preserved in marine sediments archive the physical and chemical conditions under which they built their shells. To interpret the paleoceanographic information contained in fossil foraminifera, the proxy signals have to be attributed to the habitat of individual species. Much of our knowledge on habitat depth is based on indirect methods, which reconstruct the depth at which the largest portion of the shell has been calcified. However, habitat depth can be best studied by direct observations in stratified plankton nets. Here we present a synthesis of living planktonic foraminifera abundance data in vertically resolved plankton net hauls taken in the eastern North Atlantic during twelve oceanographic campaigns between 1995 and 2012. Live (cytoplasm-bearing) specimens were counted for each depth interval and the vertical habitat at each station was expressed as average living depth (ALD). This allows us to differentiate species showing an ALD consistently above 100 m (e.g. Globigerinoides ruber white and pink), indicating a shallow habitat; species occurring from the surface to the subsurface (e.g. Globigerina bulloides, Globorotalia inflata, Globorotalia truncatulinoides); and species inhabiting the subsurface (e.g. Globorotalia scitula and Globorotalia hirsuta). For 17 species with variable ALD, we assessed whether their depth habitat at a given station could be predicted by mixed layer (ML) depth, temperature in the ML and chlorophyll a concentration in the ML. The influence of seasonal and lunar cycle on the depth habitat was also tested using periodic regression. In 11 out of the 17 tested species, ALD variation appears to have a predictable component. All of the tested parameters were significant at least in one case, with both seasonal and lunar cyclicity as well as the environmental parameters being able to explain up to > 50 % of the variance. Whereas G. truncatulinoides, G. hirsuta and G. scitula appear to deepen their living depth towards the summer, populations of Trilobatus sacculifer appears to descend in the water column towards the new moon. In all other species, properties of the mixed layer explained more of the observed variance. Chlorophyll a concentration seems least important for ALD, whilst shoaling of the habitat with deepening of the ML is observed most frequently. We observe both shoaling and deepening of species habitat with increasing temperature. Further, we observe that temperature and seawater density at the depth of the ALD were not equally variable among the studied species, and their variability showed no consistent relationship with depth habitat. According to our results, depth habitat of individual species changes in response to different environmental and ontogenetic factors and consequently planktonic foraminifera exhibit not only species-specific mean habitat depths but also species-specific changes in habitat depth.

scholarly journals Factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern North Atlantic

2017 ◽  
Vol 14 (4) ◽  
pp. 827-859 ◽  
Author(s):  
Andreia Rebotim ◽  
Antje H. L. Voelker ◽  
Lukas Jonkers ◽  
Joanna J. Waniek ◽  
Helge Meggers ◽  
...  
Keyword(s):  
Water Column ◽  
Chlorophyll A ◽  
Mixed Layer ◽  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Individual Species ◽  
Habitat Depth ◽  
Chlorophyll A Concentration ◽  
Eastern North Atlantic ◽  
Species Specific

Abstract. Planktonic foraminifera preserved in marine sediments archive the physical and chemical conditions under which they built their shells. To interpret the paleoceanographic information contained in fossil foraminifera, the recorded proxy signals have to be attributed to the habitat and life cycle characteristics of individual species. Much of our knowledge on habitat depth is based on indirect methods, which reconstruct the depth at which the largest portion of the shell has been calcified. However, habitat depth can be best studied by direct observations in stratified plankton nets. Here we present a synthesis of living planktonic foraminifera abundance data in vertically resolved plankton net hauls taken in the eastern North Atlantic during 12 oceanographic campaigns between 1995 and 2012. Live (cytoplasm-bearing) specimens were counted for each depth interval and the vertical habitat at each station was expressed as average living depth (ALD). This allows us to differentiate species showing an ALD consistently in the upper 100 m (e.g., Globigerinoides ruber white and pink), indicating a shallow habitat; species occurring from the surface to the subsurface (e.g., Globigerina bulloides, Globorotalia inflata, Globorotalia truncatulinoides); and species inhabiting the subsurface (e.g., Globorotalia scitula and Globorotalia hirsuta). For 17 species with variable ALD, we assessed whether their depth habitat at a given station could be predicted by mixed layer (ML) depth, temperature in the ML and chlorophyll a concentration in the ML. The influence of seasonal and lunar cycle on the depth habitat was also tested using periodic regression. In 11 out of the 17 tested species, ALD variation appears to have a predictable component. All of the tested parameters were significant in at least one case, with both seasonal and lunar cyclicity as well as the environmental parameters explaining up to > 50 % of the variance. Thus, G. truncatulinoides, G. hirsuta and G. scitula appear to descend in the water column towards the summer, whereas populations of Trilobatus sacculifer appear to descend in the water column towards the new moon. In all other species, properties of the mixed layer explained more of the observed variance than the periodic models. Chlorophyll a concentration seems least important for ALD, whilst shoaling of the habitat with deepening of the ML is observed most frequently. We observe both shoaling and deepening of species habitat with increasing temperature. Further, we observe that temperature and seawater density at the depth of the ALD were not equally variable among the studied species, and their variability showed no consistent relationship with depth habitat. According to our results, depth habitat of individual species changes in response to different environmental and ontogenetic factors and consequently planktonic foraminifera exhibit not only species-specific mean habitat depths but also species-specific changes in habitat depth.

Calcification depth of deep-dwelling planktonic foraminifera from eastern North Atlantic: evidence from stable oxygen isotope ratios of shells from plankton tows 

2021 ◽  
Author(s):  
Andreia Rebotim ◽  
Antje H. L. Voelker ◽  
Lukas Jonkers ◽  
Joanna J. Waniek ◽  
Michael Schulz ◽  
...  
Keyword(s):  
Water Column ◽  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Great Majority ◽  
Large Degree ◽  
Individual Species ◽  
Surface Mixed Layer ◽  
Globorotalia Truncatulinoides ◽  
Stable Oxygen ◽  
Eastern North Atlantic

<p>Stable oxygen isotopes (δ<sup>18</sup>O) of planktonic foraminifera are one of the most used tools to reconstruct environmental conditions of the water column. Since different species live and calcify at different depths in the water column, the δ<sup>18</sup>O of sedimentary foraminifera reflects to a large degree the vertical habitat and interspecies δ<sup>18</sup>O differences and can thus potentially provide information on the vertical structure of the water column. To fully unlock the potential of foraminifera as recorders of past surface water properties, it is necessary to understand how and under what conditions the environmental signal is incorporated into the calcite shells of individual species. Deep-dwelling species play a particularly important role in this context, since their calcification depth reaches below the surface mixed layer. Here we report δ<sup>18</sup>O measurements made on four deep-dwelling Globorotalia species collected with stratified plankton tows in the Eastern North Atlantic. Size and crust effects on the δ<sup>18</sup>O signal were evaluated showing that a larger size increases the δ<sup>18</sup>O of <em>Globorotalia inflata</em> and <em>Globorotalia hirsuta</em>, and a crust effect is reflected in a higher δ<sup>18</sup>O in <em>Globorotalia truncatulinoides</em>. The great majority of the δ<sup>18</sup>O values can be explained without invoking disequilibrium calcification. When interpreted in this way the data imply depth-integrated calcification with progressive addition of calcite with depth to about 300 m for <em>G. inflata</em> and to about 500 m for <em>G. hirsuta</em>. In <em>Globorotalia scitula</em>, despite a strong subsurface maximum in abundance, the vertical δ<sup>18</sup>O profile is flat and appears dominated by a surface layer signal. In <em>G. truncatulinoides</em>, the δ<sup>18</sup>O profile follows equilibrium for each depth, implying a constant habitat during growth at each depth layer. The δ<sup>18</sup>O values are more consistent with the predictions of the Shackleton (1974) paleotemperature equation, except in <em>G. scitula</em>, which shows values more consistent with the Kim and O’Neil (1997) prediction.  In all cases, we observe a difference between the level where most of the specimens were present and the depth where most of their shell appears to calcify.</p>

scholarly journals Calcification depth of deep-dwelling planktonic foraminifera from the eastern North Atlantic constrained by stable oxygen isotope ratios of shells from stratified plankton tows

2019 ◽  
Vol 38 (2) ◽  
pp. 113-131 ◽  
Author(s):  
Andreia Rebotim ◽  
Antje Helga Luise Voelker ◽  
Lukas Jonkers ◽  
Joanna J. Waniek ◽  
Michael Schulz ◽  
...  
Keyword(s):  
Water Column ◽  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Great Majority ◽  
Large Degree ◽  
Individual Species ◽  
Surface Mixed Layer ◽  
Oxygen Isotope Ratios ◽  
Stable Oxygen ◽  
Eastern North Atlantic

Abstract. Stable oxygen isotopes (δ18O) of planktonic foraminifera are one of the most used tools to reconstruct environmental conditions of the water column. Since different species live and calcify at different depths in the water column, the δ18O of sedimentary foraminifera reflects to a large degree the vertical habitat and interspecies δ18O differences and can thus potentially provide information on the vertical structure of the water column. However, to fully unlock the potential of foraminifera as recorders of past surface water properties, it is necessary to understand how and under what conditions the environmental signal is incorporated into the calcite shells of individual species. Deep-dwelling species play a particularly important role in this context since their calcification depth reaches below the surface mixed layer. Here we report δ18O measurements made on four deep-dwelling Globorotalia species collected with stratified plankton tows in the eastern North Atlantic. Size and crust effects on the δ18O signal were evaluated showing that a larger size increases the δ18O of G. inflata and G. hirsuta, and a crust effect is reflected in a higher δ18O signal in G. truncatulinoides. The great majority of the δ18O values can be explained without invoking disequilibrium calcification. When interpreted in this way the data imply depth-integrated calcification with progressive addition of calcite with depth to about 300 m for G. inflata and to about 500 m for G. hirsuta. In G. scitula, despite a strong subsurface maximum in abundance, the vertical δ18O profile is flat and appears dominated by a surface layer signal. In G. truncatulinoides, the δ18O profile follows equilibrium for each depth, implying a constant habitat during growth at each depth layer. The δ18O values are more consistent with the predictions of the Shackleton (1974) palaeotemperature equation, except in G. scitula which shows values more consistent with the Kim and O'Neil (1997) prediction. In all cases, we observe a difference between the level where most of the specimens were present and the depth where most of their shell appears to calcify.

scholarly journals Supplementary material to "Factors controlling the depth habitat of planktonic foraminifera in the subtropical eastern North Atlantic"

2016 ◽  
Author(s):  
Andreia Rebotim ◽  
Antje H. L. Voelker ◽  
Lukas Jonkers ◽  
Joanna J. Waniek ◽  
Helge Meggers ◽  
...  
Keyword(s):  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Supplementary Material ◽  
Eastern North Atlantic

Depth-habitat reorganization of planktonic foraminifera across the Albian/Cenomanian boundary

Paleobiology ◽  
2010 ◽  
Vol 36 (3) ◽  
pp. 357-373 ◽  
Author(s):  
Atsushi Ando ◽  
Brian T. Huber ◽  
Kenneth G. MacLeod
Keyword(s):  
Stable Isotope ◽  
North Atlantic ◽  
Planktonic Foraminifera ◽  
Environmental Parameters ◽  
Implicit Assumption ◽  
Ocean Stratification ◽  
Evolutionary Changes ◽  
Surface Dwelling ◽  
Cooling Trend ◽  
Species Specific

New mid-Cretaceous stable isotope (δ18O and δ13C) records of multiple planktonic foraminiferal species and coexisting coccoliths from Blake Nose (western North Atlantic) document a major depth-ecology reorganization of planktonic foraminifera. Across the Albian/Cenomanian boundary, deep-dwellingPraeglobotruncana stephaniandRotalipora globotruncanoidesadapted to living at a shallower depth, while, at the same time, the population of surface-dwellingParacostellagerina libycadeclined. Subsequently, the opportunistic speciesHedbergella delrioensisshifted to a deep environment, and the deep-dwelling formsRotalipora montsalvensisandRotalipora reichelifirst appeared. The primary paleoenvironmental cause of the observed changes in planktonic adaptive strategies is uncertain, yet their coincidence with an earliest Cenomanian cooling trend reported elsewhere implicates the importance of reduced upper-ocean stratification. Although there has been an implicit assumption that the species-specific depth habitats of fossil planktonic foraminifera were invariant through time, planktonic paleoecology is a potential variable. Accordingly, the possibility of evolutionary changes in planktonic foraminiferal depth ecology should be a primary consideration (along with other environmental parameters) in paleoceanographic interpretations of foraminiferal stable isotope data.

scholarly journals Upper ocean mixing controls the seasonality of planktonic foraminifer fluxes and associated strength of the carbonate pump in the oligotrophic North Atlantic

2014 ◽  
Vol 11 (8) ◽  
pp. 12223-12254 ◽  
Author(s):  
K. H. Salmon ◽  
P. Anand ◽  
P. F. Sexton ◽  
M. Conte
Keyword(s):  
Mixed Layer ◽  
North Atlantic ◽  
Community Dynamics ◽  
Phytoplankton Bloom ◽  
North Atlantic Ocean ◽  
Planktonic Foraminifera ◽  
Upper Ocean ◽  
Late Winter ◽  
Planktonic Foraminifer ◽  
Spring Phytoplankton Bloom

Abstract. Oligotrophic regions represent up to 75% of Earth's open-ocean environments, and are typically characterized by nutrient-limited upper-ocean mixed layers. They are thus areas of major importance in understanding the plankton community dynamics and biogeochemical fluxes. Here we present fluxes of total planktonic foraminifera and eleven planktonic foraminifer species from a bi-weekly sediment trap time series in the oligotrophic Sargasso Sea, subtropical western North Atlantic Ocean at 1500 m water depth, over two ∼2.5 year intervals, 1998–2000 and 2007–2010. Foraminifera flux was closely correlated with total mass flux and with carbonate and organic carbon fluxes. We show that the planktonic foraminifera flux increases approximately five-fold during the winter–spring, contributing up to ∼40% of the total carbonate flux, driven primarily by increased fluxes of deeper dwelling ("globorotaliid") species. Interannual variability in total foraminifera flux, and in particular fluxes of the deep dwelling Globorotalia truncatulinoides, Globorotalia hirsuta, Globorotalia inflata, were related to differences in seasonal mixed layer dynamics affecting the strength of the spring phytoplankton bloom and export flux, and by the passage of mesoscale eddies. The heavily calcified, dense carbonate tests of deeper dwelling species (3 times denser than surface dwellers) can contribute up to 90% of the foraminiferal-derived carbonate in this region during late winter-early spring, implying a high seasonality of the biological carbonate pump in oligotrophic oceanic regions. Our data suggest that climate cycles, such as the North Atlantic Oscillation, that modulate the depth of the mixed layer, intensity of nutrient upwelling and primary production could also modulate the strength of the biological carbonate pump in the oligotrophic North Atlantic.

scholarly journals Glider observations of the Northwestern Iberian Margin during an exceptional summer upwelling season

2020 ◽  
Author(s):  
Callum Rollo ◽  
Karen Heywood ◽  
Rob Hall ◽  
Eric Desmond Barton ◽  
Jan Kaiser
Keyword(s):  
Chlorophyll A ◽  
North Atlantic ◽  
Shelf Break ◽  
Dissolved Oxygen Concentration ◽  
Low Oxygen ◽  
Near Surface ◽  
North West ◽  
The North ◽  
Eastern North Atlantic ◽  
Iberian Margin

<p>We present results from a 2 month deployment of an ocean glider over the Northwestern Iberian Margin. Glider observations during the exceptionally strong 2010 summer upwelling season resolved the evolution of physical and biogeochemical variables during two upwelling events. Upwelling brought low oxygen Eastern North Atlantic Central Water from 190 m depth onto the shelf up to a depth of 50 m. During the two observed periods of upwelling,<br>equatorward transport over the shelf increased from 0.13 (± 0.04) Sv to 0.18 (± 0.08) Sv and a poleward jet developed over the shelf-break. The persistent upwelling favourable winds maintained equatorward flow on the outer shelf for two months with no reversals during relaxation periods, a phenomenon not previously observed. During upwelling, near surface chlorophyll a concentration increased by more than 6 mg m<sup>-3</sup> . Dissolved oxygen concentration in the near surface increased by more than 40 μmol kg<sup>-1</sup> , 6 days after the chlorophyll a maximum.</p><p><br>This was the first and, to date, only deployment of a glider over the North West Iberian Margin. A single glider was able to occupy a cross shelf section for two months, without the need for a costly ship based campaign. This presentation highlights some of the challenges of using gliders to study shelf break regions.</p>

scholarly journals Reconciling single chamber Mg/Ca with whole test δ<sup>18</sup>O in surface to deep dwelling planktonic foraminifera from the Mozambique Channel

2014 ◽  
Vol 11 (12) ◽  
pp. 17255-17298
Author(s):  
J. Steinhardt ◽  
C. Cléroux ◽  
L. de Nooijer ◽  
G.-J. Brummer ◽  
R. Zahn ◽  
...  
Keyword(s):  
Mass Balance ◽  
Mixed Layer ◽  
Planktonic Foraminifera ◽  
Balance Model ◽  
Single Specimen ◽  
Mass Balance Model ◽  
Single Test ◽  
Single Chamber ◽  
Mozambique Channel ◽  
Species Specific

Abstract. Most planktonic foraminifera migrate vertically through the water column during life, meeting a range of depth-related conditions as they grow and calcify. For reconstructing past ocean conditions from geochemical signals recorded in their shells it is therefore necessary to know vertical habitat preferences. Species with a shallow habitat and limited vertical migration will reflect conditions of the surface mixed layer and short- and meso-scale (i.e. seasonal) perturbations therein. Species spanning a wider range of depth habitats, however, will contain a more heterogeneous, intra-specimen variability (i.g. Mg/Ca and δ18O), which is less for species calcifying below the seasonal mixed layer (SML). Here we present results on single-chamber Mg/Ca combined with single shell δ18O and δ13C of surface water Globigerinoides ruber, the thermocline-dwelling Neogloboquadrina dutertrei and Pulleniatina obliquiloculata and the deep dweller Globorotalia scitula from the Mozambique Channel. Species-specific Mg/Ca, δ13C and δ18O data combined with a depth-resolved mass balance model confirm distinctive migration and calcification patterns for each species as a function of hydrography. Whereas single specimen δ18O not always reveal changes in depth habitat related to hydrography (i.g. temperature), measured Mg/Ca of the last chambers can only be explained by active migration in response to changes in temperature stratification. Since species show different responses to changes in hydrography, their shell chemistry can be used to reconstruct different components of the past ocean climate system such as seasonality and depth stratification. Here we present combined single-specimen δ18O and single-chamber Mg/Ca measurements for different species, providing a composite of thermocline and sub-thermocline conditions. These results allow for species-specific reconstruction of calcification depths, using a mass balance model, of four species of planktonic foraminifera. This shows that the single chamber Mg/Ca and single test δ18O are in agreement with each other and in line with the changes in hydrography induced by eddies. Whereas single chamber Mg/Ca are most affected eddy frequency, seasonality is reflected more clearly in single test δ18O.

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