Anthropogenically induced environmental changes in the northeastern Adriatic Sea in the last 400 years (Panzano Bay, Gulf of Trieste)

Abstract

<p><strong>Abstract.</strong> Shallow and sheltered marine embayments in urbanized areas are prone to the accumulation of pollutants, but little is known about the historical baselines of such marine ecosystems. Here we study foraminiferal assemblages, geochemical proxies and sedimentological data from 1.6 m long sediment cores to uncover ~ 400 years of anthropogenic pressure from mining, port and industrial zones in the Gulf of Trieste, Italy. <br><br> From 1600 to 1900 AD, element concentrations and foraminiferal assemblages point to negligible effects of agricultural activities. The only significant anthropogenic activity during this period is mercury mining in the hinterlands of the gulf, releasing high amounts of mercury into the bay and significantly exceeding today's Italian sediment quality guidelines (SQG) and the standards on the effects of trace elements to benthic organisms (ERL and ERM). Nonetheless, the fluctuations in the concentrations of mercury do not correlate with changes in the composition and diversity of foraminiferal assemblages due to its nonbioavailability. Intensified agricultural and maricultural activities in the first half of the 20th century caused slight nutrient enrichment and a minor increase in foraminiferal diversity. Intensified port and industrial activities in the second half of 20th century increased the normalised trace element concentrations and persistent organic pollutants (PAH, PCB) in the topmost part of the core, with solely Ni exceeding Italian SQG, ERL and ERM. This increase caused only minor changes in the foraminiferal community because foraminifera in Panzano Bay have a long history of adaptation to naturally elevated trace element concentrations. <br><br> Our study underlines the importance of using an integrated, multidisciplinary approach in reconstructing the history of environmental and anthropogenic changes in marine systems. Given the prolonged human impacts in coastal areas like the Gulf of Trieste, such long term baseline data are crucial for interpreting the present state of marine ecosystems.</p>

Molluscan benthic communities at Brijuni Islands (northern Adriatic Sea) shaped by Holocene sea-level rise and recent human eutrophication and pollution

“…Holocene sediment cores from the north-eastern Adriatic show a succession from fluvial to brackish and marine facies ( Cattaneo and Trincardi, 1999 ; Orogelec et al, 1991 ). High concentrations of Hg, Cu and Zn characterize modern deposits that accumulated during the past thousand years in the Gulf of Trieste ( Covelli et al, 2006 ; Mautner et al, 2018 ; Vidović et al, 2016 ). Temporary sediment storage and resuspension mainly occur during the winter storm period caused by north-easterly cold winds (bora), but also during strong summer winds from southeast (sirocco) ( Frignani et al, 2005 ).…”

“…Four sediment types were defined: clay (<2 µm), silt (2–63 µm), sand (63 µm–2 mm), and the fraction > 2 mm, which mostly consisted of biogenic material. Elemental concentrations (Hg, Cu, Cr, Ni, Pb, As, Cd, Zn, Mn, Fe) were estimated with inductively coupled plasma atomic emission spectrometry (ICP-AES), organic pollutants (PCBs, PAHs) with liquid chromatography, and nutrients (N, C, TOC) with the elemental analyzer CHN 2400, according to the protocol in Vidović et al (2016) . They were determined in the core layers: 1 cm, 5 cm, 9 cm, 24 cm, 46 cm, 69 cm, 85 cm, 105 cm, 126 cm and 151 cm.…”

“…Benthic mortalities caused by oxygen depletion and mucilage events have occurred here periodically for centuries ( Crema et al, 1991 ; Danovaro et al, 2009 ; Tomašových et al, 2017 ) but became more frequent and widespread during the last 40 years ( Degobbis et al, 2000 ; Faganeli et al, 1985 ; Justić, 1991 ; Stachowitsch, 1991 ). The increase in the frequency of hypoxia was promoted by anthropogenic eutrophication through agriculture and wastewater disposal ( Barmawidjaja et al, 1995 ; Mavrič et al, 2010 ; Nerlović et al, 2011 ; N’siala et al, 2008 ; Vidović et al, 2016 ). Overfishing and pollution negatively affected ecosystem functioning, leading to changes in food-web structure and to reduced efficiency of bentho-pelagic coupling ( Barausse et al, 2009 ; Coll et al, 2007 ).…”