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  • Periodic Report Summary 1 - ARAMACC (Annually-resolved archives of marine climate change - development of molluscan sclerochronology for marine environmental monitoring and climatology)

Periodic Report Summary 1 - ARAMACC (Annually-resolved archives of marine climate change - development of molluscan sclerochronology for marine environmental monitoring and climatology)

The use of annual banding in long-lived bivalve molluscs to investigate changes in the marine environment (“sclerochronology”, or “shell-ring research”) is an important and fascinating branch of climate science. Chronologies built in this way can, like those constructed using tree-rings, be crossdated back in time, allowing the investigation in great detail of the environmental and climatic changes that occurred before and during the period of increasing anthropogenic impacts.

ARAMACC (“Annually Resolved Archives of MArine Climate Change”) is the first large scale collaborative project focussing on this field. It is a multi-partner Initial Training Network whose aim is to train the next generation of shell-ring researchers and also to carry out original research involving all the scientific fields that are associated with the construction and environmental response of shell carbonate. ARAMACC is a consortium of eight Full Participants and four Associated Partners, providing a full programme of scientific research and structured training to ten ESRs (PhD students) and one ER (postdoc).

The scientific part of ARAMACC consists of (i) the construction of a network of shell-based chronologies built using shells collected from the seabed at sites along the axis of the North Atlantic Current (NAC); (ii) the development of techniques for using the shell-based chronologies and other high resolution marine palaeodata developed in ARAMACC as inputs for coupled ocean-atmosphere models; (iii) the determination of the controls on calcification rate and the timing of growth check formation in selected bivalve mollusc species; (iv) the development of novel techniques for the interpretation of shell geochemistry and crystallography as environmental proxies.

ARAMACC training is carried out during seven events, of which two are research cruises aimed at developing skills associated with doing research at sea, while the other five combine training in skills specific to the fields of sclerochronology and climatology with coaching in a wide range of generic and transferable skills.

The impact of ARAMACC is implemented through (i) the identification of applications of shell-based proxies in the commercial and regulatory sectors and their transmission to potential beneficiaries; and (ii) the establishment of a public data bank of all sclerochronological data (with metadata) for the North Atlantic realm.

Multicentennial shell-based chronologies have been constructed for the North Sea, St Kilda and the Faroe Islands, and multidecadal chronologies are in development for the Bay of Brest and Viking Bank. Fabian Bonitz has built separate chronologies for the east and west sides of the Faroe Islands (the east chronology extends back to 1688 and is the longest chronology so far produced in ARAMACC). Tamara Trofimova has been working on shells collected on Viking Bank (which is at the southern end of the NAC) and has used live and dead-collected shells to construct a 96-year chronology. Stella Alexandroff has collected shells from the remote Scottish island of St Kilda, and also from around some of the Hebridean islands, and has been developing chronologies from all of these sites. Amy Featherstone has developed a 75-year chronology for Glycymeris glycymeris shells from the Bay of Brest. Juan Estrella has been extending a North Sea chronology that had already been part developed at Bangor, and has been milling shells from the same chronology for subsequent stable isotope analysis.

Maria Pyrina has been analysing climate simulations for the North Atlantic region over the past millennium and comparing them with climate reconstructions based on marine (and terrestrial) proxies in order to identify unbiased models for the North Atlantic region. These models will later be used for comparisons with the proxy records being produced in ARAMACC.

Ariadna Purroy has completed 18 months of sample collection of three species from three sites in the Adriatic Sea. Biological and chemical analyses have been carried out on water samples and the bivalve specimens. Genetic comparison has been carried out between G. glycymeris from Bay of Brest and Glycymeris pilosa from the Adriatic to confirm the species identification of the latter, which had previously been thought to be G. glycymeris. Irene Ballesta has been carrying out in situ experiments in northern Norway and close to the island of Texel, Netherlands, using specimens of Arctica islandica.

Each of the two ESRs based at JGU Mainz has submitted one manuscript and has a second one nearly ready for submission. Liqiang Zhao has been investigating the complex controls on Sr and Ba incorporation into shells of Corbicula fluminea, and has a paper on this under review at Paleo3. Stefania Milano has manuscripts in preparation related to the links between shell crystal fabrics of Cerastoderma edule and temperature, and to the effect of acidification on the microstructure, hardness and elasticity of shells of the same species.

Juliane Steinhardt is working on commercial and regulatory aspects of sclerochronology and is currently writing an extended report on environmental applications of sclerochronology. She has also attended a JPI Oceans conference and has visited the Associated Partner (Akvaplan niva) in Tromsø.

The training element of the project has been continuing as planned, and the two training cruises and the first three workshops have completed successfully.

Several shell chronologies are currently under construction, and initial milling has been carried out to obtain samples for geochemical analysis, in particular to calibrate stable carbon and oxygen isotope data from the shells with modern instrumental measurements. The longest chronology (back to 1688 = 325 years) has been constructed for the Faroe Islands, where the long-lived bivalve Arctica islandica is very common. The east and west Faroes chronologies have been compared and show strong similarity back to 1960 even though they are separated by ~100km and the Faroes land mass. This indicates a homogeneous environment on the Faroese Shelf. Glycymeris glycymeris shells from the western Scottish island of St Kilda appeared very large and very fresh (in that they showed no evidence of bioerosion), and we were very surprised to find after radiocarbon dating that they were around 3,500 years old. Crossmatching between these shells was consistent with the radiocarbon dating, a result which demonstrates the reliability of both techniques. The length of the floating St Kilda chronology is about 300 years.

ARAMACC has been structured around the idea of sclerochronology as an extended scientific field that goes beyond the basic remit of chronology construction, stable isotope geochemistry and climate reconstruction to deal with the underlying challenges related to the animal’s complex environment and the shell formation process and with extended applications of sclerochronology in climate modelling and environmental monitoring. As a result we anticipate that our scientific legacy will be a set of project proposals that build on each aspect of ARAMACC and use its results to guide the appropriate direction of research. In addition, we will focus on the extension of this line of research beyond pure science, bringing its potential as a long term baseline monitor for the marine environment to the attention of policy makers and the commercial sector.

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United Kingdom


Life Sciences
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