Spatial variations in Ba/Cashell fingerprints of Glycymeris pilosa along the eastern Adriatic Sea
Graphical abstract
Introduction
Bivalve shells contain periodic growth patterns, i.e., growth lines and increments visible on the shell surface and in cross-sections (Richardson, 2001). These growth patterns can be used to assign time (e.g., calendar years) to corresponding shell portions. Geochemical properties of deposited shell material can yield temporally aligned proxy data of environmental conditions prior to instrumental recordings (e.g., Schöne et al., 2011; Royer et al., 2013; Schöne and Gillikin, 2013; Füllenbach et al., 2015; Reynolds et al., 2016; Prendergast et al., 2017; Markulin et al., 2019). Longevity of some bivalve species exceeds several decades (eg. Tridacna gigas; Elliot et al., 2009) and even centuries (eg. Arctica islandica; Schöne et al., 2005a; Wanamaker et al., 2008; Butler et al., 2013). Pairing with fossil specimens can enable reconstruction of environmental change in the more distant past (e.g. Scourse et al., 2006; Schöne et al., 2011; Butler et al., 2013). In the last two decades, the field of sclerochronology has been rapidly developing, relating variations in growth increments widths and geochemical composition of shell carbonate (e.g. Schöne et al., 2005b; McConnaughey and Gillikin, 2008; Black et al., 2009; Thébault et al., 2009; Reynolds et al., 2017; Tanabe et al., 2017) with environmental variations.
Due to their worldwide distribution (Huber, 2010), longevity and distinct annual growth patterns (e.g., Reynolds et al., 2013, Walliser et al., 2016; Peharda et al., 2018), shells of glycymeridids represent an important sclerochronological archive of proxy data that can help to elucidate past changes in the marine environment. Several recent studies identified Glycymeris pilosa as an interesting target species for paleoclimate reconstructions as well as for investigating the relationship between environmental changes and biology in the Mediterranean Sea. Distinct annual growth lines present in shells of this species enable chronology construction (Peharda et al., 2016, 2018, 2019a) as well as to temporally align geochemistry data including stable isotope values (Peharda et al., 2019b, c), radioactive carbon (Peharda et al., 2019d) and trace and minor element data (Markulin et al., 2019).
Barium (Ba) has been identified as an important trace element for studying geochemical and oceanic processes (Stecher et al., 1996) and is incorporated in bivalve shells making them an important data archive of past environmental variability (for review see Gillikin et al., 2008). Ba/Cashell time-series obtained from marine bivalves are characterised by flat background signals erratically interrupted by pronounced peaks that are synchronous between studied specimens indicating external forcing (e.g. Gillikin et al., 2006; Elliot et al., 2009; Thébault et al., 2009; Marali et al., 2017a; Doré et al., 2020). Ba/Cashell time-series data can potentially be used to distinguish between different sampling sites (Norrie et al., 2019).
According to previous studies, background Ba/Cashell data may reflect salinity (e.g., Gillikin et al., 2006, 2008; Marali et al., 2017a), whereas the interpretation of Ba/Cashell peaks is still debated (Marali et al., 2017a; Ballestra-Artero et al., 2018). Dissolved or particulate Ba in ambient seawater (Gillikin et al., 2006; Carroll et al., 2009), primary production (e.g. Stecher et al., 1996; Carroll et al., 2009; Elliot et al., 2009; Thébault et al., 2009) and spawning events (Gillikin et al., 2006) have been suggested as possible controls of Ba/Cashell. Recent laboratory studies showed that a large number of environmental and physiological variables, such as temperature, food level, Ba/Cawater and shell growth control Ba/Cashell (Zhao et al., 2017; Ballestra-Artero et al., 2018; Wanamaker and Gillikin, 2019).
The main objective of this study was to test the hypothesis that Ba/Cashell signals in G. pilosa shells do not vary along the coastal areas of the eastern Adriatic Sea. Recent study conducted by Markulin et al. (2019) analysed elements in G. pilosa shells from one site in the north Adriatic Sea and showed highly synchronised Ba/Cashell peaks coinciding with the dense water formation during early 2012. By analysing specimens from different sites along the Adriatic Sea coast, we wanted to gain an understanding on how local versus regional drivers influence the geochemical composition of the shells in the Mediterranean Sea. To achieve this, we analysed Ba/Cashell over nine consecutive years in G. pilosa collected from five sites. Furthermore, we wanted to gain an insight into temporal variations of Ba/Cashell and have analysed shells of three older (>50 years) bivalves from Drače.
Section snippets
Sample collection and preparation
Glycimeris pilosa specimens were collected alive by SCUBA and skin diving from five sites along the eastern Adriatic Sea: (1) Pag (3–5 m depth, 44°27′42.012″ N, 015°1′36.012″ E); (2) Pašman Channel (1.5–3 m depth, 43°56′52.68″N, 015°23′15.03″E); (3) Cetina (3–5 m depth, 43°26′12.984″ N, 016°41′13.992″E); (4) Živogošće (3–5 m depth, 43°10′57.02″N, 17°9′42.91″E) and (5) Drače (4–5 m depth, 42°56′10.54″N, 017°28′23.71″E) (Fig. 1). Sampling was performed during several occasions in 2014, 2015 and
Results
In polished cross-sections, the growth pattern was divided into dark grey growth bands and opaque, white increments (Fig. 2). A distinct annual growth line was seldom observed when viewed under the light microscope, which made it difficult to define precisely where a growth increment (representing the main growing season) started and ended. However, based on findings of previous studies, we suspect the annual winter line (representing ca. January to March) within the centre of the white
Ba/Cashell time-series
At each locality, studied Glycymeris pilosa specimens showed synchronous Ba/Cashell signals, suggesting that the incorporation of barium into the shells was controlled by the same environmental events. Furthermore, during some time intervals (e.g., 2009–2010), Ba/Cashell signals were even synchronous among different sites, indicating large-scale environmental controls on barium availability. In a recent study of three aragonitic bivalves including G. pilosa, Markulin et al. (2019) found highly
CRediT authorship contribution statement
Krešimir Markulin: Conceptualization, Methodology, Writing - original draft, Visualization, Writing - review & editing. Hana Uvanović: Methodology, Visualization, Writing - review & editing. Regina Mertz-Kraus: Conceptualization, Methodology, Writing - review & editing. Bernd R. Schöne: Conceptualization, Methodology, Writing - review & editing. Žarko Kovač: Methodology, Writing - review & editing. Jasna Arapov: Methodology, Writing - review & editing. Melita Peharda: Conceptualization,
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
Sampling at Pag Bay, Pašman Channel and Cetina River mouth was conducted in the framework of Marie Curie ITN project ARAMACC (604802), while in Živogošće and Drače it was conducted as a part of Croatian Science Foundation, Croatia, SCOOL (IP-2014-09-5747). Precipitation data were provided by the Meteorological and Hydrological Service of the Republic of Croatia. Ivica Janeković provided temperature and salinity modelled data. Data related to river Neretva were obtained from the Federal
References (76)
- et al.
Environmental and biological factors influencing trace elemental and microstructural properties of Arctica islandica shells
Sci. Total Environ.
(2018) - et al.
Multi-proxy reconstructions of northeastern Pacific sea surface temperature data from trees and Pacific geoduck
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2009) - et al.
Quantifying submarine groundwater discharge in the coastal zone via multiple methods
Sci. Total Environ.
(2006) - et al.
Variability of marine climate on the North Icelandic Shelf in a 1357-year proxy archive based on growth increments in the bivalve Arctica islandica
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2013) - et al.
2020. Assessment of Ba/Ca in Arctica islandica shells as a proxy for phytoplankton dynamics in the Northwestern Atlantic Ocean
Estuar. Coast Shelf Sci.
(2020) - et al.
Profiles of trace elements and stable isotopes derived from giant long-lived Tridacna gigas bivalves: potential applications in paleoclimate studies
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2009) - et al.
Mg in aragonitic bivalve shells: seasonal variations and mode of incorporation in Arctica islandica
Chem. Geol.
(2008) - et al.
Strontium/lithium ratio in aragonitic shells of Cerastoderma edule (Bivalvia) - a new potential temperature proxy for brackish environments
Chem. Geol.
(2015) - et al.
Variations of fatty acid contents in selected tissues of the female dog cockle (Glycymeris glycymeris L., Mollusca, Bivalvia) during the annual cycle
Comp. Biochem. Physiol. Mol. Integr. Physiol.
(1999) - et al.
Barium uptake into the shells of the common mussel (Mytilus edulis) and the potential for estuarine paleo-chemistry reconstruction
Geochem. Cosmochim. Acta
(2006)