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Sclerochronology : tool for uncovering environmental drivers in a semi-enclosed sea

Sclerochronology : tool for uncovering environmental drivers in a semi-enclosed sea.

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Sclerochronology : tool for uncovering environmental drivers in a semi-enclosed sea

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  1. Sclerochronology: tool for uncovering environmental drivers in a semi-enclosed sea Melita Peharda1, Ivica Vilibić1, Tomislav Džoić1, Krešimir Markulin1, Natalija Dunić1, Hrvoje Mihanović1, Miroslav Gačić2, Bryan Black3, Hana Uvanović1, Daria Ezgeta-Balić1, Jadranka Šepić1, Žarko Kovač1, Ivan Župan4 1 Institute of Oceanography and Fisheries, Split, Croatia 2OGS, Trieste, Italy 3Marine Science Institute, University of Texas as Austin, Austin, USA 4University of Zadar, Zadar, Croatia

  2. What is sclerochronology? • Sclerochronology isanalogous to dendrochronology, the study of annualrings in trees, and equally seeks to deduceorganismallife history traits as well as to reconstruct records ofenvironmental and climatic change through space andtimeSclerochronology is the study of physical and chemical variations in theaccretionary hard tissues of organisms, and the temporalcontext in which they formed • It focuses primarily upon growth patterns reflectingannual, monthly, fortnightly, tidal, daily, and sub-dailyincrements of time entrained by a host of environmentaland astronomical pacemakers • Jones et al. 2007 Arctica islandica Longevity >500 years Chronologies >1,300 godina Lack of sclerochronological studies in the Mediterranean!!!

  3. Target species? Three sprecies from genus Glycymeris live in the Adriatic Sea: G. nummaria G. bimaculata G. pilosa Largest of three species, ~ 60 years Bušelić et al. (2015) – 16 year chronology Smallest of three species Longevity ~ 20 years G. glycymeris vs. G. pilosa Purroy et al. (2016) Other species: Ezgeta-Balić et al. (2011) Max longevity 44 years Very few specimens older than 20 years Pecten jacobaeus Callista chione

  4. Project: Sclerochronology as a tool for detecting long-term Adriatic environmental changes (SCOOL)Duration: June 2015 - June 2019Funder: Croatian Science FoundationBudget: ca. 120 kEuroPrincipal Investigator: Melita Peharda UljevićLeading institution: Institute of Oceanography and Fisheries • Project objectives: • to develop a network of bivalve chronologies for the eastern Adriatic • to research different basin-scale hydrodynamic and environmental processes that drive the changes of oceanographic properties in the Adriatic Sea

  5. Bivalve sampling sites • West coast of Istra • Pag Bay • Pašman Channel • Živogošće (Makarska) • Pelješac • South Adriatic

  6. Laboratory and data analysis • > 50 large shells per species and location • Embeding in epoxy resin • Cutting, grinding and polishing (STRUERS) • Etching – preparation of acetate peels • 0.1 M HCl - 2 min, or 0.3 M HCl - 30 sec • Image Pro Premiere – software – image analysis • COFECHA, ARSTAN

  7. Validation of growth lines visual cross-dating using – „list year” method A. May 2012., B. May 2014., C. and April 2015, scale bar 200 µm. Full circles – wide growth increments, open circles – narrow increments.

  8. Case study: Glycymeris pilosa, Barbariga, Istra • Bivalve sampling: • Barbariga – 10 m depth, SCUBA • Collection 2015 and 2016 • Environmental parameters (monthly values): • ERA Interim: total precipitation (TP), downward net heat flux (NHF), air temperature at 2 m (T2M), sea surface temperature (SST) • NEMOMED12 climate model: sea surface temperature (SSTN), sea surface salinity (SSSN) • Po River discharge at Pontelagoscuro (PO) • Absolute Dynamic Topography (ADT) difference between the centre and the periphery of the Northern Ionian Gyre

  9. Istra chronology • Processed 66 shells, 30 used for chronology • Longevity 35-72 years • Clear growth lines and synchronized shell growth within population • Earliest measured increment year 1953 • Statistically robust 1978-2016 (38 years) Acetate peel of specimen S3P99 (scale bar 500 µm), B. Individual detrended growth series (1954-2016) and their average (1978 statistically robust chronology in black, prior to 1978 in dashed line), C. Sample depth (grey shading area) and EPS values computed in a 30 year window with indicated arbitrary value of EPS value ≥0.85.

  10. Istra chronology - geochemistry Peharda et al. 2017. Chemical Geology, in press • Analysis of stable isotopes indicate periods with low growth and generation of growth lines • For G. Pilosa growth lines are occurring during late summer (September-October)

  11. Correlations with local freshwater budget Correlation • Correlations were not significant between chronologies and monthly water budget variables (TP and PO) in the year of growth (October-September) and preceeding 6 months • Local freshwater inputs (including nutrient inputs) are not significantly influencing growth rates. 90% 95% Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Correlation 90% 95% Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

  12. Correlations with local temperatures Correlation 90% 95% Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep • Correlations were significant with winter (February-March) and summer (June-September) sea surface temperatures (both SST and SSTN) • The higher are winter temperatures the higher is the bivalve growth • The higher are summer temperatures the lower is the bivalve growth (due to a stress to the organism)

  13. Correlations with remote forcing (i.e. BiOS) 90% 95% Correlation • Correlations were significant with winter (October-February) ADT • The stronger is the cyclonic BiOS (i.e. higher inflow of high-saline waters from the Levantine Basin) the weaker is the bivalve growth Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep ADT (Oct-Feb)

  14. Ongoing activities • Glycymeris sp. • Preliminary analysis of fossil samples – estimated longevity >100 years • 14C analysis in process • Possibilities for EXTENDING CHRONOLOGIES back in time (>50 years) and/or constructing floating chronologies?

  15. Plans for future • Extending chronology - analysis of fossil samples • Construction of chronologies for multiple locations – other parts of the Mediterranean • Construction of multi-species chronologies • Chronologies for commercially important species • Geochemical analysis of shells – stable isotopes (δ18O i δ13C) and elements (Mo, Ba, Li) • Correlating basin-wide (Adriatic, Mediterranean) chronologies to global, regional and local climate and environmental indices and processes

  16. Split, Croatia, 17-20 June 2019 Sessions

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