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  • 1
    Online Resource
    Online Resource
    Molluscan benthic communities at Brijuni Islands (northern Adriatic Sea) shaped by Holocene sea-level rise and recent human eutrophication and pollution
    SAGE Publications ; 2018
    In:  The Holocene Vol. 28, No. 11 ( 2018-11), p. 1801-1817
    Details
    In: The Holocene, SAGE Publications, Vol. 28, No. 11 ( 2018-11), p. 1801-1817
    Abstract: The effects of and the interplay between natural and anthropogenic influences on the composition of benthic communities over long time spans are poorly understood. Based on a 160-cm-long sediment core collected at 44 m water depth in the NE Adriatic Sea (Brijuni Islands, Croatia), we document changes in molluscan communities since the Holocene transgression ~11,000 years ago and assess how they were shaped by environmental changes. We find that (1) a transgressive lag deposit with a mixture of terrestrial and marine species contains abundant seagrass-associated gastropods and epifaunal suspension-feeding bivalves, (2) the maximum-flooding phase captures the establishment of epifaunal bivalve-dominated biostromes in the photic zone, and (3) the highstand phase is characterized by increasing infaunal suspension feeders and declining seagrass-dwellers in bryozoan-molluscan muddy sands. Changes in the community composition between the transgressive and the highstand phase can be explained by rising sea level, reduced light penetration, and increase in turbidity, as documented by the gradual up-core shift from coarse molluscan skeletal gravel with seagrass-associated molluscs to bryozoan sandy muds. In the uppermost 20 cm (median age 〈 200 years), however, epifaunal and grazing species decline and deposit-feeding and chemosymbiotic species increase in abundance. These changes concur with rising concentrations of nitrogen and organic pollutants due to the impact of eutrophication, pollution, and trawling in the 20th century. The late highstand benthic assemblages with abundant bryozoans, high molluscan diversity, and abundance of soft-bottom epi- and infaunal filter feeders and herbivores represent the circalittoral baseline community largely unaffected by anthropogenic impacts.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/0959683618788651
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2018
    detail.hit.zdb_id: 2027956-5
    SSG: 14
    SSG: 3,4
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  • 2
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    Online Resource
    Inferring time averaging and hiatus durations in the stratigraphic record of high‐frequency depositional sequences
    Wiley ; 2022
    In:  Sedimentology Vol. 69, No. 3 ( 2022-04), p. 1083-1118
    Details
    In: Sedimentology, Wiley, Vol. 69, No. 3 ( 2022-04), p. 1083-1118
    Abstract: A sequence stratigraphic framework predicts that time averaging and hiatus durations will be long at times of fastest sea‐level rise. This prediction does not necessarily apply to environments where carbonate production keeps up with sea‐level rise and where undetected hiatuses decouple short‐term from long‐term sedimentation rates. The taphonomic clock, however, which measures the residence time of skeletal particles in the mixed layer, can estimate the duration of hiatuses if the rate of skeletal alteration is slow and if skeletal particles endure long‐term exposure in the mixed layer. Here, time averaging is calibrated by using evidence from alteration of bivalves in a metre‐scale Holocene sequence in the Adriatic Sea. In this sequence, transgressive molluscan lags, a maximum‐flooding zone shell bed with bivalves, and highstand bryomol assemblages were all deposited under similar long‐term sedimentation rates ( ca 0.01 to 0.03 cm year −1 ) and exhibit millennial time averaging. Median ages of valves stained by pyrite and cemented by high‐magnesium calcitic micritic envelopes exceeding ca 1000 years indicate that: (i) these authigenic processes are slow in subsurface zones with reducing conditions (with prolonged sulphate reduction and carbonate ions sourced from dissolved shells in the surface zones); and (ii) subsurface micrite precipitation prolongs the disintegration half‐lives of valves exhumed to surface zones from decades to millennia. The high abundance of stained valves, valves with micrite envelopes, and valves with composite alteration (encrusters and borers colonizing stained and cemented grains) thus identifies hiatuses and skeletal concentrations time‐averaged to 〉 1000 years. The upcore decrease in abundance of valves with composite alteration, coupled with temporally‐constant long‐term sedimentation rates and time averaging, indicates that a temporal decline in sediment exhumation was compensated by a decline in burial of skeletal carbonate produced by molluscs.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.v69.3
    DOI: 10.1111/sed.12936
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2020955-1
    detail.hit.zdb_id: 206889-8
    SSG: 13
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  • 3
    Online Resource
    Online Resource
    A decline in molluscan carbonate production driven by the loss of vegetated habitats encoded in the Holocene sedimentary record of the Gulf of Trieste
    Wiley ; 2019
    In:  Sedimentology Vol. 66, No. 3 ( 2019-04), p. 781-807
    Details
    In: Sedimentology, Wiley, Vol. 66, No. 3 ( 2019-04), p. 781-807
    Abstract: Carbonate sediments in non‐vegetated habitats on the north‐east 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: (i) monitoring of ecosystems prior to the 20th century was scarce; and (ii) 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 〉 1000 years and Corbula gibba shells are older by 〉 2000 years than shells of co‐occurring Gouldia minima . This age difference is driven by temporally disjunct production of two species coupled with decimetre‐scale mixing. Stratigraphic unmixing shows that Corbula gibba declined in abundance during the highstand phase and increased again during 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. Gouldia minima and herbivorous gastropods associated with macroalgae or seagrasses are abundant in the top‐core increments but are rarely alive. Although Gouldia 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 sea floor in the Gulf of Trieste reflect inactive production that was sourced by heterozoan carbonate factory in algal or seagrass habitats.
    Type of Medium: Online Resource
    ISSN: 0037-0746 , 1365-3091
    URL: Issue
    URL: Article
    DOI: 10.1111/sed.2019.66.issue-3
    DOI: 10.1111/sed.12516
    RVK:
    RB 10121
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 2020955-1
    detail.hit.zdb_id: 206889-8
    SSG: 13
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  • 4
    Online Resource
    Online Resource
    Assessing anoxia, recovery and carbonate production setback in a hemipelagic Tethyan basin during the Toarcian Oceanic Anoxic Event (Western Carpathians)
    Elsevier BV ; 2020
    In:  Global and Planetary Change Vol. 195 ( 2020-12), p. 103366-
    Details
    In: Global and Planetary Change, Elsevier BV, Vol. 195 ( 2020-12), p. 103366-
    Type of Medium: Online Resource
    ISSN: 0921-8181
    URL: Article
    DOI: 10.1016/j.gloplacha.2020.103366
    RVK:
    RA 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 20361-0
    detail.hit.zdb_id: 2016967-X
    SSG: 13
    SSG: 14
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