Effects of environmental change on the calcification intensity of planktonic Foraminifera: A case study from Sapropel S5

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Proceedings Chapter

Reference

Effects of environmental change on the calcification intensity of planktonic Foraminifera: A case study from Sapropel S5

WEINKAUF, Manuel, et al.

WEINKAUF, Manuel, et al . Effects of environmental change on the calcification intensity of planktonic Foraminifera: A case study from Sapropel S5. In: Aberhan, M., Fröbisch, J., Hampe, O., Kiessling, W., Müller, J., Neumann, C., Voss, M. & Witzmann, F. Centenary Meeting of the Paläontologische Gesellschaft 2012 . Berlin : 2012. p. 192-193

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192 Abstracts

1Senckenberg Forschungsinstitut und Naturmuseum, Forschungsstation Grube Messel, Markstr. 35, D-64409 Messel, Germany

2Institute of Biology and Soil Sciences, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia

3Forsteler Strasse 1, 64739 Höchst Odw., Germany The Berothidae (Insecta: Neuroptera), also called bead- ed or hairy lacewings, is a small neuropteran family with almost 100 species in over 20 genera. It is still under dis- cussion whether Rhachiberothinae should be considered as a family of its own or should be included in Berothi- dae, but the two taxa most probably are sister-groups.

Today, berothids are distributed in a wide range of tropi- cal to warmer temperate regions of the world. The adults are brown in colour and small to medium sized. They have been collected with light traps in diverse habitats, and little is known about their microhabitats. The larvae of only few extant berothid genera are known, and the knowledge of the larval biology is restricted to a few members of the subfamily Berothinae. Like many other neuropteran taxa, they have three larval instars. Infor- mation on the larval life style is available for only two genera, Lomamyia Banks, which is distributed in North America, and Podallea Navás from Africa. In these two berothine genera, the first and third instars live and move actively in the nests of termites and prey on them; the second instar has a very different morphology, it is inactive and does not feed. Fossils of Berothidae have been found since the Middle Jurassic, they comprise mostly adults. The ma- jority of fossils were described from the Cretaceous, only few have been recorded from the Tertiary. Larvae are only known from Eocene Baltic and Rovno amber.

In this study four larval specimens of Berothidae are recorded from Eocene Baltic amber. The inclusions are kept at the Senckenberg amber collection and at the pri- vate collections of Thomas Weiterschan (Höchst Oden- wald) and Christel and Hans Werner Hoffeins (Ham- burg). Two of the larvae probably represent first instars, judged from their sizes around 2 mm. The other two larvae are bigger, and probably represent third larval instars. One of the probable third instar larvae shows remains of possible spider silk in the head region. Addi- tionally, in this specimen deformations of the abdomen are present, which still require some explanation.

S25 – New data on the Annulata Events in the Moravian Karst (Famennian, Czech Republic)

Weiner T.

E-mail: tomasweiner@volny.cz

Masaryk University, Department of Geological Sciences, Kotlářská 2, 611 37 Brno, Czech Republic

The Annulata Events belong to most important global events in the Famennian and correspond to the Upper Palmatolepis trachytera zone. They are lithologically characterized by anoxic to dysoxic dark grey to black lay- ers, typically shales or limestones, which are intercalated in sequences of different facies. These event beds yield a rich fauna, especially clymenids, pelecypods, orthoc- one nautiloids and ostracods. The black limestone lenses from the Moravian Karst, later assigned to the Annulata Events, were recorded for the first time by Rzehak (1910), who described their typical fauna from a locality near Brno-Líšeň. Similar facies were later discovered in the Mokrá quarry (Dvořák 1988). Recently, Annulata Event beds were found in 4 new localities. The contribution is focused on the preliminary stratigraphical results based on conodont biostratigraphy, gammaspectrometry and carbon isotope geochemistry. Based on conodonts, the black limestone lenses from a locality near Brno-Líšeň can be correlated with lower Annulata event.

S3 – Effects of environmental change on the calcifica- tion intensity of planktonic Foraminifera: a case study from Sapropel S5

Weinkauf M.¹*, T. Moller², M. Koch³& M. Kučera¹

*E-mail: manuel.weinkauf@uni-tuebingen.de

1Eberhard-Karls-Universität Tübingen, Mathematisch–

Naturwissenschaftliche Fakultät, Fachbereich Geowis- senschaften, Hölderlinstraße 12, 72074 Tübingen, Ger- many; current address: University Bremen, MARUM, Leobener Str., 28359 Bremen, Germany

Naturwissenschaftliche Fakultät, Fachbereich Geowissen- schaften, Hölderlinstr. 12, 72074 Tübingen, Germany

Naturwissenschaftliche Fakultät, Fachbereich Geowis- senschaften, Hölderlinstr. 12, 72074 Tübingen, Germany;

current address: Johann Wolfgang Goethe-Universität, In- stitut für Geowissenschaften, Facheinheit Paläontologie, Altenhöferallee 1, 60438 Frankfurt am Main, Germany Planktonic Foraminifera are important marine calcifiers, responsible for almost half of the present-day open-ocean production of biogenic carbonate. Therefore, it is important to understand which environmental parameters influence the calcification of the foraminiferal test. The aim of this study is to test the influence of the exposure to different levels of environmental stress, including ter- minal stress leading to extinction, on the calcification of planktonic foraminifers. For this purpose we have chosen four species of planktonic Foraminifera from a sediment core section covering the onset of Sapropel S5 in the Eastern Mediterranean (c.125 ka), where the ecosystem was exposed to a high stress environment. For all species,

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193 Abstracts

intervals exhibiting local extinctions or strong drops in abundance were selected to investigate responses of the calcification intensity of the tests. This offers the unique chance to assess the reactions of planktonic Foraminif- era to severe environmental stress.

Several specimens, taken from a narrow sieve fraction, were individually measured and weighed together using an ultrabalance (d = 0.1 μg); the mean weight of the tests was then normalised for the mean test size in each sample.

It could be shown that the shallow dwelling, symbiont- bearing species Orbulina universa shows a distinct drop in test weight at the onset of the sapropel, and that the weight is further continuously decreasing thereafter for about 4000 years, until a local extinction of the species.

The calcification intensity of that species is also well correlated with stable oxygen isotope values retrieved from tests of Globigerinoides ruber, which are probably in- dicative of the intensity of freshwater influx. In the deep dwelling species Globorotalia scitula evidence for a con- tinuous decrease in calcification intensity could be found, that started as early as 3000 years before the onset of the sapropel. Globorotalia inflata, a species that mainly lives in intermediate water depths, shows some fluctuations in test weight, but those cannot be attributed to the available information on the timing of environmental change.

Interestingly, this species shows much larger intra-sample variations of the test weight than any of the other species investigated. Globigerinoides ruber (pink), for which results are still pending, will serve as a second shallow- dwelling species to be investigated. The main influential parameters for the observed fluctuations in calcification intensity are as yet unknown, with changes in freshwater influx from Africa—possibly causing changes in the carbon equilibrium system in the Eastern Mediterranean—or changes in sea water salinity being considered as possible reasons. We show that the calcification intensity of planktonic Foraminifera is subject to fluctuations that can be attributed to environmental changes, and that both long-term (i.e. thousands of years) and short-term (i.e.

100–200 years) reactions can be observed.

S5 – Morphological deviations in planktonic Foraminifera as a reaction to enhanced environmental stress: opportunities and problems

Weinkauf M.¹*, T. Moller², M. Koch³& M. Kučera¹

*E-mail: manuel.weinkauf@uni-tuebingen.de

Naturwissenschaftliche Fakultät, Fachbereich Geowis- senschaften, Hölderlinstraße 12, 72074 Tübingen, Ger- many; current address: University Bremen, MARUM, Leobener Str., 28359 Bremen, Germany

Naturwissenschaftliche Fakultät, Fachbereich Geowis-

senschaften, Hölderlinstr. 12, 72074 Tübingen, Germany

Naturwissenschaftliche Fakultät, Fachbereich Geowissen- schaften, Hölderlinstraße 12, 72074 Tübingen, Germany;

current address: Johann Wolfgang Goethe-Universität, In- stitut für Geowissenschaften, Facheinheit Paläontologie, Altenhöferallee 1, 60438 Frankfurt am Main, Germany Foraminifera are amongst the best known groups of fossil protists, featuring a remarkably complete and continu- ous fossil record. This fossil record holds considerable potential to study how species phenotype (morphology) responds to environmental perturbation. In this respect, it is of particular interest to study such cases where the environmental perturbation on the studied population led to extinction. Such cases are impossible to study at present, because extinctions under natural conditions cannot be predicted. This study investigates the morphological reaction of planktonic Foraminifera when exposed to vary- ing levels of environmental stress, ultimately resulting in extinction. To this end, a sediment section from the East- ern Mediterranean was chosen, that covers the onset of Sapropel S5 (c.125 ka). This event was associated with local extinctions of several species of planktonic Fo- raminifera, and thus offers the chance to investigate the reaction of those species to environmental stress during a natural experiment with known outcome.

In three selected species of planktonic Foraminifera a variety of morphological traits, such as size, roundness, growth pattern, outline, and incidence of abnormal mor- photypes, was investigated. In Orbulina universa, which shows two local extinctions in the studied time interval, an increase in size and the incidence of abnormal mor- photypes could be observed during both intervals immediately preceding the extinction levels. Furthermore, the species shows a significant shift in test roundness with the onset of the sapropel, with roundness values being generally stable in both intervals before and after sapropel onset, respectively. Globorotalia scitula shows a local extinction shortly before the onset of the sapropel. Beside a generally variable but otherwise stable morphology a distinct deviation in growth rate and variability of growth rate can be observed immediately before the species be- comes locally extinct. In Globorotalia inflata no morphological reaction to the observed environmental forcing could be observed; the species became extinct immediately after sapropel onset without an obvious reaction of its shell morphology. These results indicate that morphological reactions on environmental stress in planktonic Foraminifera occur on different time scales and that the type and level of reaction is species-specific. On large time scales long-lasting, stable deviations in morphology can be observed, associated with large environmental shifts. Over short time periods, as a result of fatal stress leading to local extinction, other morphological reactions are obvious. These can most likely be attributed to a re- laxation of growth patterns and appear to operate over a time interval of decades or less. We speculate that severe