Linking the high-resolution acoustic and sedimentary facies of a transgressed Late Quaternary alluvial plain (Gulf of Trieste, northern Adriatic)

Novak, Ana; Šmuc, Andrej; Poglajen, Sašo; Vrabec, Marko

doi:10.1016/j.margeo.2019.106061

Cited by 16 publications

(28 citation statements)

References 87 publications

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“…The differences in the intensity of bioturbation between (i) perturbation regimes with limited mixing by bioturbation and (ii) background regimes with intense and deep mixing by bioturbation can thus generate a dichotomy in the resolution of the marine fossil record on continental shelves. On one hand, the majority of the fossil record that formed in shelf ecosystems with intense bioturbation is probably averaged to centuries or millennia and rich in gaps [65], as is also observed in the nothern Adriatic Sea [66,67]. On the other hand, the window for preservation of highly resolved ecological dynamic opens in the aftermath of anoxic and hypoxic events (leading to limited or totally absent bioturbation, [68][69][70][71]) on the present-day marine shelves and was probably open in the wake of major ecosystem perturbations in the geological past [73][74].…”

Section: Discussionmentioning

confidence: 94%

Ecological regime shift preserved in the Anthropocene stratigraphic record

et al. 2020

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Palaeoecological data are unique historical archives that extend back far beyond the last several decades of ecological observations. However, the fossil record of continental shelves has been perceived as too coarse (with centennial-millennial resolution) and incomplete to detect processes occurring at yearly or decadal scales relevant to ecology and conservation. Here, we show that the youngest (Anthropocene) fossil record on the northern Adriatic continental shelf provides decadal-scale resolution that accurately documents an abrupt ecological change affecting benthic communities during the twentieth century. The magnitude and the duration of the twentieth century shift in body size of the bivalve Corbula gibba is unprecedented given that regional populations of this species were dominated by small-size classes throughout the Holocene. The shift coincided with compositional changes in benthic assemblages, driven by an increase from approximately 25% to approximately 70% in median per-assemblage abundance of C. gibba . This regime shift increase occurred preferentially at sites that experienced at least one hypoxic event per decade in the twentieth century. Larger size and higher abundance of C. gibba probably reflect ecological release as it coincides with an increase in the frequency of seasonal hypoxia that triggered mass mortality of competitors and predators. Higher frequency of hypoxic events is coupled with a decline in the depth of intense sediment mixing by burrowing benthic organisms from several decimetres to less than 20 cm, significantly improving the stratigraphic resolution of the Anthropocene fossil record and making it possible to detect sub-centennial ecological changes on continental shelves.

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Section: Discussionmentioning

confidence: 94%

Ecological regime shift preserved in the Anthropocene stratigraphic record

et al. 2020

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“…The bays and estuaries along the Istrian peninsula that were flooded during the maximum ingression were filled with prograding sediments during the latest Holocene (Faivre et al ., 2011; Felja et al ., 2015; Novak et al ., 2020a). Nonetheless, with the exception of bays, the shoreline along most of the Istrian peninsula did not prograde during the latest phase of sea‐level stabilization owing to an extremely reduced fluvial sediment supply and sediment bypassing, and sediments deposited during the highstand phase are thus typically less than 1 m thick (Tomašových et al ., 2019b; Novak et al ., 2020b). The thickness of the bryomol unit overlying the gravelly shell bed at Brijuni approximately matches the vertical increase in the accommodation space as predicted by the relative sea‐level rise estimated for Brijuni.…”

Section: Resultsmentioning

confidence: 99%

Inferring time averaging and hiatus durations in the stratigraphic record of high‐frequency depositional sequences

et al. 2021

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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 metrescale 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 À1 ) and exhibit millennial time averaging. Median ages of valves stained by pyrite and cemented by highmagnesium 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.

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“…The main task is the acquisition of data that are related to the morphology of the seabed, in order to reconstruct the underwater three-dimensional landscape, using geophysical (Single Beam Echo Sounder and Side Scan Sonar) and optical (underwater cameras for photogrammetry) instruments [78][79][80][81][82][83][84][85].…”

Section: Geomorphological and Gis Analysismentioning

confidence: 99%

New Geomorphological and Historical Elements on Morpho-Evolutive Trends and Relative Sea-Level Changes of Naples Coast in the Last 6000 Years

Mattei

Aucelli

Caporizzo

et al. 2020

Water

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This research aims to present new data regarding the relative sea-level variations and related morpho-evolutive trends of Naples coast since the mid-Holocene, by interpreting several geomorphological and historical elements. The geomorphological analysis, which was applied to the emerged and submerged sector between Chiaia plain and Pizzofalcone promontory, took into account a dataset that is mainly composed of: measurements from direct surveys; bibliographic data from geological studies; historical sources; ancient pictures and maps; high-resolution digital terrain model (DTM) from Lidar; and, geo-acoustic and optical data from marine surveys off Castel dell’ Ovo carried out by using an USV (Unmanned Surface Vehicle). The GIS analysis of those data combined with iconographic researches allowed for reconstructing the high-resolution geomorphological map and three new palaeoenvironmental scenarios of the study area during the Holocene, deriving from the evaluation of the relative sea-level changes and vertical ground movements of volcano-tectonic origin affecting the coastal sector in the same period. In particular, three different relative sea-level stands were identified, dated around 6.5, 4.5, and 2.0 ky BP, respectively at +7, −5, and −3 m MSL, due to the precise mapping of several paleo-shore platforms that were ordered based on the altimetry and dated thanks to archaeological and geological interpretations.

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Linking the high-resolution acoustic and sedimentary facies of a transgressed Late Quaternary alluvial plain (Gulf of Trieste, northern Adriatic)

Cited by 16 publications

References 87 publications

Ecological regime shift preserved in the Anthropocene stratigraphic record

Ecological regime shift preserved in the Anthropocene stratigraphic record

Inferring time averaging and hiatus durations in the stratigraphic record of high‐frequency depositional sequences

New Geomorphological and Historical Elements on Morpho-Evolutive Trends and Relative Sea-Level Changes of Naples Coast in the Last 6000 Years

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