10.5061/DRYAD.RJ4CG1T
Tomasovych, Adam
University of Vienna
Gallmetzer, Ivo
University of Vienna
Haselmair, Alexandra
University of Vienna
Kaufman, Darrell S.
Northern Arizona University
Mavric, Borut
National Institute of Biology
Zuschin, Martin
University of Vienna
Data from: A decline in molluscan carbonate production driven by the loss
of vegetated habitats encoded in the Holocene sedimentary record of the
Gulf of Trieste
Dryad
dataset
2019
Geochronology
Anthropocene
Amino acid racemization
Bivalvia
Gastropoda
Gouldia minima
Holocene
Corbula gibba
2019-06-28T00:00:00Z
2019-06-28T00:00:00Z
en
https://doi.org/10.1111/sed.12516
1241691 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Carbonate sediments in non-vegetated habitats on the NE Adriatic shelf are
dominated by shells of molluscs. However, the rate of carbonate molluscan
production prior to the 20th century eutrophication and overfishing on
this and other shelves remains unknown because (1) monitoring of
ecosystems prior to the 20th century was scarce and (2) ecosystem history
inferred from cores is masked by condensation and mixing. Here, based on
geochronological dating of four bivalve species, carbonate production
during the Holocene is assessed in the Gulf of Trieste, where algal and
seagrass habitats underwent a major decline during the 20th century.
Assemblages of sand-dwelling Gouldia minima and opportunistic Corbula
gibba are time-averaged to > 1,000 years and C. gibba shells are
older by >2,000 years than shells of co-occurring G. minima. This
age difference is driven by temporally disjunct production of two species
coupled with decimeter-scale mixing. Stratigraphic unmixing shows that
Corbula gibba declined in abundance during the highstand phase and
increased again in the 20th century. In contrast, one of the major
contributors to carbonate sands, Gouldia minima, increased in abundance
during the highstand phase, but declined to almost zero abundance over the
past two centuries. G. minima and herbivorous gastropods associated with
macroalgae or seagrasses are abundant in the top-core increments but are
rare alive. Although G. minima is not limited to vegetated habitats, it is
abundant in such habitats elsewhere in the Mediterranean Sea. This
live-dead mismatch reflects the difference between highstand baseline
communities (with soft-bottom vegetated zones and hard-bottom Arca beds)
and present-day oligophotic communities with organic-loving species.
Therefore, the decline in light penetration and the loss of vegetated
habitats with high molluscan production traces back to the 19th century.
More than 50% of the shells on the seafloor in the Gulf of Trieste reflect
inactive production that was sourced by heterozoan carbonate factory in
algal or seagrass habitats.
Supplement Table 1-core dataAbsolute abundances of molluscs in two cores
at Piran 1 and Piran 2, including two surface living assemblages collected
by Van Veen grabs at the same sites in 2014 (1 mm mesh size). Complete
valves or fragments with umbo preserved were selected from the >1
mm sieve fraction of each increment, identified to species level, and
counted. For each species, the higher number of single valves (either
right or left) was added to the number of double-valved specimens to get
the final count in each increment.Supplement Table 2-Gouldia age dataAmino
acid racemization data and calibrated estimates of postmortem age of
Gouldia minima collected from the shell bed at Piran 1 and Piran
2.Supplement Table 3-Corbula age dataAmino acid racemization data and
calibrated estimates of postmortem age of Corbula gibba and Piran
2.Supplement Table 4-LA dataAbsolute abundances of molluscs in living
assemblages collected by Van Veen grabs at 11 stations in 2011.Gouldia age
unmixing finalR language source code for analyses of age data and age
unmixing
Adriatic Sea
Mediterranean Sea