Naslov
The relation between the composition of foraminiferal assemblages and granulometric properties of the sediments from three salt marshes (Eastern Adriatic coast, Croatia)
(The relation between the composition of foraminiferal assemblages and granulmoetric properties of the sediments from three salt marshes (Eastern Adriatic coast, Croatia))

Autori
Čančar, Marina ; Križnjak, Kristina ; Neral, Natali ; Felja, Igor ; Ćosović, Vlasta

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
6th Regional Scientific Meeting on Quaternary Geology: Seas, Lakes and Rivers ; Ljubljana, 27–29 September 2021 Book of abstracts E-book © 2021, Geološki zavod Sovenije, Ljubljana / Petra Jamšek Rupnik, Ana Novak - Ljubljana, 2021, 12-13

Skup
6th Regional Scienfic Meeting on Quaternary Geology: Seas, Lakes and Rivers

Mjesto i datum
Ljubljana, Slovenija, 27.09.2021. - 29.09.2021

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
salt marsh, foraminiferal assemblages, granulometric properties

Sažetak
Being located at the boundary between the marine and continental environments, the marginal marine areas are very important for the study of sea- level changes, reconstruction of the coastal marine paleoenvironments, archeological studies and biomonitoring. Along the eastern Adriatic coast, a few studies have been conducted in such areas (Ćosović et al., 2011 ; Shaw et al., 2016). For this study, three locations were selected: the mouth of the Mirna River, the Čižići salt marsh and the Nin Bay. Shallow (up to 10 cm long) sediment cores were collected along the land-to- sea transect, using an Eijkelkamp hand auger. The sediment cores were sliced into 2 cm thick intervals from the surface to the bottom, and two intervals were studied in detail for micropaleontological and granulometric analyses, the uppermost (0 – 2 cm) and the lowermost (8 – 10 cm) interval. Following the micropaleontological procedures, including sample standardization, foraminiferal genera and species were determined, as well as absolute and relative abundance and ecological (biodiversity) indices. Fine-grained muddy sediments from the salt marsh at the mouth of the Mirna River, show low diversity (14 foraminiferal genera and 8 species were found). In the shallower interval (0 – 2 cm), the values of Shannon-Wiener (H) index ranged from 0.9 to 1.93, and in the deeper interval (8 – 10 cm) from 0.7 to 1.5. Ammonia tepida (Cushman), Trochamina inflata (Montagu), Porosononion granosum (d'Orbigny) and Haynesina depressula (Walker & Jacob) are the dominant species, all indicative of a restricted marginal, shallow- marine environment with possible salinity fluctuations (brackish conditions). Abundance of T. inflata increases at deeper intervals, which may be a consequence of accumulation of tests over time (seasonal, a time averaging process) or the occupation of deeper sediment habitats. A total of 27 foraminiferal genera and 42 species were identified in the sandy-muddy sediments of the Čižići salt marsh. The most abundant species is A. tepida, followed by A. parkinsoniana (d'Orbigny), Haynesina sp. and T. inflata. Biodiversity indices increase with distance from the sea (H= 1.38 – 2.40 in shallower interval ; H= 1.68 – 2.58 in deeper interval). A total of 30 genera and 44 species were identified in the sandy sediments of the Nin Bay, with A. beccarii (Linnaeus) as the most abundant species. Diversity index values are consistent (H= 2.29 – 2.76 for shallower and 1.62 – 2.51 for deeper intervals), suggesting a marine environment with normal to variable salinity. Common features of all foraminiferal assemblages are the dominance of shallow infaunal species, among which representatives of genus Ammonia predominate. The constant presence of deformed tests characterized assemblages. A large proportion of the sand component with many reworked foraminiferal tests in Nin Bay and Čižići indicates a larger input from the surrounding flysch deposits, in contrast to the Mirna area were the terrigenous input is limited.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Interdisciplinarne prirodne znanosti

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