Logo Università degli Studi di Milano



 
 

Mesozoic calcareous plankton (nannofossils and foraminifera): taxonomy, biostratigraphy, paleoecology, evolutionary history and biocalcification.  

Elisabetta Erba, Maria Rose Petrizzo, Cinzia Bottini, Cristina Casellato, Alessia Barchetta, Giulia Faucher, Gabriele Gambacorta, Silvia Gilardoni, Fabio Russo, Francesca Falzoni, Dario Soldan

 

1 - The response of calcareous plankton to ocean acidification during Mesozoic oceanic anoxic events –MIUR-PRIN 2010-2011 (Erba)

See also the full description of research of the Milano Unit, comprehensive of micro-, macro-paleontology and vertebrate paleontology.

Elisabetta Erba, Maria Rose Petrizzo, Cinzia Bottini, Cristina Casellato, Alessia Barchetta, Giulia Faucher, Fabio Russo

The main motivation of this research project is the understanding of massive, anthropogenic CO2 emissions causing climate change and altering ecosystems, perhaps introducing irreversible modifications. The Earth's biological systems are continuously evolving/adapting, but causes and consequences of changes in the Anthropocene are difficult to ascertain, as Industrialization has caused accelerated rising of atmCO2 at rates unprecedented in Earth history. Major concerns are addressed to the possibility that biodiversity loss will soon derive from biota failure in sustaining rapid warming. The emergence of climate change as a widely accepted and crucial issue for society and governments has recently enabled the recognition of ocean acidification (OA), raised by anthropogenic CO2 emissions.

In the open ocean the major calcareous plankton groups are calcite-forming coccolithophores and foraminifera and aragonite-forming pteropods. Despite their tiny sizes, coccolithophores comprise the most efficient carbonate rock-forming organisms since Jurassic times and the sinking of coccoliths/nannoliths has produced calcareous oozes in the past 200 million years. The amount of CO2 in the ocean/atmosphere system exerts a direct control on calcareous nannoplankton, because of the biochemical reactions involved in both photosynthesis and biocalcification. Experiments on some living coccolithophores show non-linear, species-specific changes in calcification rates, photosynthesis, physiology and malformation.

Planktonic foraminifera appeared in the Jurassic, but became relevant for pelagic carbonate sedimentation only in the Early Cretaceous. The effects of OA on living planktonic foraminifera show reduction of shell thickness and weight (Bijma et al 1999; Russell et al 2004) as also attested by results obtained on foraminiferal shells in modern sediments (Moy et al 2009).

Oceanic Anoxic Events (OAEs) are considered natural Earth System experiments, which allow investigation of (a) processes associated with emissions of greenhouse gases and pollutants in climate and ocean dynamics; (b) role of ocean acidification on planktonic calcifiers; (c) changes in biodiversity and dynamics of marine ecosystems to understand the functioning of biotic sinks.

The geological record of OAEs merit careful examination of how the Earth System can adapt to and overcome extreme episodes of environmental change. We are investigating the three major OAEs: the Toarcian-OAE (~ 183 Ma, Early Jurassic), the early Aptian OAE1a (~ 120 Ma, Early Cretaceous) and the latest Cenomanian OAE2 (~93 Ma, Late Cretaceous). Moreover, a detailed examination of the “Mid Cenomanian Event” is in progress: high-resolution studies of the sedimentologic variations integrated with quantitative nannofossil and foraminiferal data as well as C and O stable isotopes will be used to model this turning point in the evolution of the Cretaceous oceans.

Due to the biogenic nature of sediments representing OAEs, the variations in calcareous plankton communities can be used to identify paleobiological responses before, during and after OAEs, and model the reactions of marine biota to ocean acidification. We want to quantify and model:

1) Species-specific response to onset of high-pCO2, oceanic acidification, extreme climates and fertilization, and recovery after acidification climax and in post-OAE environment.

2) Integration of nannofossil and foraminiferal changes, pointing out synchroneity/diachroneity of responses.

3) Evolutionary trends under perturbed environmental conditions. To meet these objectives  calcareous plankton will be quantitatively investigated using developed cyclochronologies

 

2 - Revision and updating of the Late Cretaceous planktonic foraminifera and calcareous nannofossils integrated biozonation for the development of the future Geological Time Scale within the EARTHTIME-EU Research Networking Program

 Elisabetta Erba, Maria Rose Petrizzo, Cinzia Bottini, Fabio Russo, Francesca Falzoni, Alessia Barchetta, Giulia Faucher

Thanks to the acknowledged expertise of in the biostratigraphy of calcareous plankton the research group is deeply involved in the EARTHTIME-The European Contribution Research Networking Program. This  European network is part of the broader international initiative “EARTHTIME: a community-based scientific effort aimed at sequencing Earth history through an integrated geochronologic and stratigraphic approach” (www.esf.org). The principal scientific objective of the network is to link the much improved numerical calibration of the Geological Time Scale to other stratigraphic disciplines (bio-, magneto-, chemo-, and cyclostratigraphy) in order to arrive at a fully integrated GTS for the last 100 million years.

 

3 - Taxonomic revision of Cretaceous planktonic foraminifera for compiling information presented in the CHRONOS online database Mesozoic Planktonic Foraminiferal Taxonomic Dictionary and publication of a hard copy atlas

Maria Rose Petrizzo, Francesca Falzoni, Alessia Barchetta, Isabella Premoli Silva, Dario Soldan,

Since 2004 the Mesozoic Planktonic Foraminiferal Working Group has been revising the taxonomy and phylogeny of Jurassic-Cretaceous planktonic foraminifera by studying and re-illustrating primary type specimens, documenting stratophenetic changes in wall microstructure and shell morphology. The working group has published results in the peer reviewed literature and has built and online taxonomic atlas as a relational database that is posted on the CHRONOS website (http://portal.chronos.org/gridsphere/gridsphere?cid=res_taxondb). The current activities of the Working Group include the regular updating of the online taxonomic dictionary and to the preparation of a hard copy taxonomic atlas that will be published in 2015.

 

4 - Cretaceous Paleoceanography of Tanzania

Maria Rose Petrizzo, Francesca Falzoni

During the past several years the research goup have joined B. T. Huber (Smithsonian Institution, Washington DC, USA), K. G. MacLeod (University of Missouri, Columbia, USA) and other members (UK, Tanzania) of the Tanzania Drilling Project (TDP) to obtain sediment samples from southeastern Tanzania where impermeable, clay-rich intervals yield some of the world’s best preserved tropical foraminifera of Cretaceous through Oligocene age. The project has conducted drilling seasons in 2007 to 2009 and cored 18 sites (TDP Sites 21-40). The goal of this project has been to provide temporal and spatial control to the Cretaceous tropical temperature record through analysis of exceptionally well preserved foraminifera (‘glassy’ foraminifera).

 

5 - Evolution of Mesozoic calcareous plankton: casual changes or biotic response to environmental perturbations? Implications for calcification and production of biogenic pelagic sediments.

Elisabetta Erba, Maria Rose Petrizzo, Cristina Emanuela Casellato, Giulia Faucher, Silvia Gilardoni, Alessia Barchetta, Francesca Falzoni

Aim of the project is the reconstruction of tempo and mode of nannoplankton and planktonic foraminiferal evolution and the causal/casual relationships with environmental changes. Examples of phyletic gradualism, punctuated equilibrium and punctuated gradualism are recorded by Mesozoic (Late Triassic through Cretaceous) calcareous plankton. Preliminary results from intervals with accelerated diversification during times of severe environmental change and of stable conditions suggest that most new forms associated to extreme events represent ephemeral adaptations, whereas species radiation mainly occurs in steady environments. We are exploring time-intervals of (1) evolutionary acceleration in absence of coeval environmental change, (2) global change marked by calcareous plankton adaptation/evolution; and (3) attenuated global change with evolutionary accelerations starting before and continuing through and after the environmental stress.

Main objectives of this research are to: (a) quantify evolutionary changes of coccolith versus nannoliths (calcareous nannoplankton) and mixed layer versus thermocline foraminifera; (b) discriminate between temporary adaptive morphologies and permanent evolutionary changes; (c) estimate time-lags or coincidence between nannoplankton and foraminiferal intra- and inter-generic evolutionary patterns; (d) identify the most common (and repetitive) evolutionary mode in calcareous plankton; (e) understand the role of environmental changes.

Morphometric analyses of selected coccolith, nannolith, and foraminiferal morphotypes are planned to separate malformation, undercalcification, overcalcification, and real ultrastructure changes. Calcification rates are used to understand interactions with the geosphere.

 

http://users.unimi.it/micropal/

Torna ad inizio pagina