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| Titel |
Dominant molluscan taxa in the northern Adriatic Sea over the last centuries: down-core changes in shell communities and their implications for an ecological history |
| VerfasserIn |
Alexandra Haselmair, Ivo Gallmetzer, Adam Tomašových, Michael Stachowitsch, Martin Zuschin |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106279
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| Publikation (Nr.) |
 EGU/EGU2015-11592.pdf |
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| Zusammenfassung |
| The northern Adriatic Sea, with its densely populated shoreline, is among the most
degraded marine ecosystems worldwide and therefore particularly suited to study
ecosystem modification under human pressure. In particular, the period of the last
500 to 1500 years witnessed major anthropogenic impacts here. The present study
reconstructs major ecological shifts over this timespan by identifying down-core
changes in molluscan death assemblages that can serve as proxies for changing
environmental conditions. Here, we focus on taxonomical down-core fluctuations and
changes in abundance of key bivalve and gastropod taxa found at seven sampling
stations spread throughout the northern Adriatic basin. At these stations, which were
chosen in order to cover different sediment types, nutrient conditions and degrees of
exploitation, several cores of 1.5 m length and diameters of 90 and 160 mm were taken
and sliced into smaller subsamples of 2 and 5 cm, respectively. The samples were
sieved through a 1 mm mesh size and all the shells found counted and identified
to species level if possible. In total, 114 bivalve and 112 gastropod species were
recorded. At the Po delta and Panzano bay stations, characterized by muddy sediments,
Corbula gibba and Kurtiella bidentata were the dominant bivalve species, Nassarius
pygmaeus and Turritella communis the most abundand gastropods. In the sandy
mud from the Brijuni islands, the bivalves Timoclea ovata and Striarca lactea were
very numerous, whereas at the Piran station, characterized by a similar sediment
composition, Gouldia minima and Corbula gibba reached the highest numbers. Overall
abundances of bivalve and gastropod species differed markedly between stations. In all
cores, the incidence of individual species varied down-core. Opposite trends were
recorded for Brijuni and Piran station: at Piran, the abundance peaked in the uppermost
sediment layers while at the Brijuni islands the number of most gastropod and bivalve
species increased with depth. The down-core changes in species abundance and
dominance can be correlated with shifts in the environmental parameters such as
sedimentation rates and sediment composition and may also indicate anthropogenic
influence. The available data from a radiometric sediment dating performed for all the
seven sampling stations help to specify the timing of these past ecological changes. |
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