Benthic Foraminiferal Assemblages in the Severely Polluted Coastal
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Revue de micropaléontologie 62 (2019) 33–44 Available online at ScienceDirect www.sciencedirect.com Research paper Benthic foraminiferal assemblages in the severely polluted coastal environment of Drapetsona-Keratsini, Saronikos Gulf (Greece) a a b Margarita D. Dimiza , Alexandra Ravani , Vasilios Kapsimalis , a,b a a,∗ Ioannis P. Panagiotopoulos , Elisavet Skampa , Maria V. Triantaphyllou a National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Department of Historical Geology–Paleontology, Athens, Greece b Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece a r t i c l e i n f o a b s t r a c t Surface sediments were collected from the coastal zone of Drapetsona–Keratsini (Saronikos Gulf, Greece) in December 2012 for determining the local benthic foraminiferal community, identifying their spatial distribution patterns, and evaluating the response of foraminiferal species to geochemical composition through the hierarchical cluster analysis, principal component analysis and Spearman’s rho correlation. Foraminifera can be classified into three distinct assemblages associated with the granulometry, elemen- tal geochemistry, particulate organic carbon content and degree of sediment contamination. A relatively low-diversity assemblage, dominated by stress-tolerant taxa with Ammonia tepida Bolivina spathulata and Bulimina elongata being the prevailing species, is characteristic of the silty seabed of the main part of Drapetsona coastal zone and the Keratsini Port central basin, where organic carbon content, aliphatic and polycyclic aromatic hydrocarbons concentrations and trace metal loads are greatly elevated. On the sandy bottom of the investigated area, relatively high frequencies of miliolids prevail. An epiphytic rotaliid-dominated assemblage is recorded in the slightly-polluted sedimentary bottom of the inner and western part of the Keratsini Port. © 2018 Elsevier Masson SAS. All rights reserved. 1. Introduction several studies have focused on estuarine and marine coastal envi- ronments exposed to direct anthropogenic contamination sources Benthic foraminifera, a significant component of meioben- such as industrial (e.g., Ferraro et al., 2006; Cherchi et al., 2009; thic communities, are highly diverse, abundant and ubiquitous Coccioni et al., 2009; Romano et al., 2009; Elshanawany et al., in all marine environments, responding quickly to environmen- 2011), urban (e.g., Mojtahid et al., 2008; Carnahan et al., 2009; tal changes due to their short reproductive cycles. Many abiotic Koukousioura et al., 2011; Martins et al., 2015, 2016; Tadir et al., factors including temperature, salinity, flux of organic matter, oxy- 2017) and agricultural wastes (e.g., Samir and El-Din, 2001) or areas gen availability, substrate type and organic and inorganic pollutants enriched with polycyclic aromatic hydrocarbons (e.g. Armynot du influence the foraminiferal composition and distribution (Murray, Châtelet et al., 2004; Ernst et al., 2006; Mojtahid et al., 2006; Lei 2006). These characteristics recommend the benthic foraminifera et al., 2015). In most studies, the changes in the levels of organic as reliable indicators for the determination of the natural envi- matter, hydrocarbons and heavy metals have multiple effects on ronmental and anthropogenic impact/pollution in estuarine and benthic foraminifera communities, ranging from modifications of shallow coastal systems (e.g., Alve, 1991, 1995; Yanko et al., 1994, their density, diversity and species composition with an increased 1998, 1999; Geslin et al., 1998; Debenay et al., 2000; Hallock et al., dominance of pollution-tolerant species to changes in reproduction 2003; Armynot du Châtelet and Debenay, 2010; Frontalini and capability, or even to test morphology. Coccioni, 2011; Schönfeld et al., 2012; Barras et al., 2014; Dimiza The Drapetsona–Keratsini coastal zone (Saronikos Gulf; Fig. 1) et al., 2016a, b; Armynot du Châtelet et al., 2018). is considered as one of the most human-impacted coastal regions A great effort has been made to understand the effects of anthro- of Greece. Until the early 1990s, the area was receiving signif- pogenic stressors on foraminiferal assemblages. In this context, icant amounts of untreated wastes from many local pollution sources (industrial and urban effluents) along the extended Athens metropolitan coastal front that significantly degraded the environ- ∗ mental quality (Galanopoulou et al., 2005). An improvement of Corresponding author. E-mail address: [email protected] (M.V. Triantaphyllou). the environmental status has recorded over the last two decades https://doi.org/10.1016/j.revmic.2018.09.001 0035-1598/© 2018 Elsevier Masson SAS. All rights reserved. 34 M.D. Dimiza et al. / Revue de micropaléontologie 62 (2019) 33–44 Fig. 1. Study area and sampling stations (modified from http://www.earth.google.com). (Simboura et al., 2014) due to the closure of several major factories western edge of the central Aegean Plateau. The Gulf is divided into and the establishment of domestic and industrial waste treatment a deeper western sub-basin (depths > 400 m) and an eastern part systems, such as the Waste Water Treatment Plant (WWTP) of by a very shallow N–S platform bounded to the south by Methana Athens, which was constructed on the islet of Psyttalia and oper- peninsula and the islands of Angistri, Aegina and Salamis. The ated for first time in 1994. Up to 2008, the WWTP was discharging northern sector of the eastern part, also known as Inner Saronikos 5 3 −1 into the Saronikos Gulf approximately 8 10 m d of treated Gulf, is relatively shallow (depths < 100 m). Sedimentation rates wastes (Zeri et al., 2009). However, many medium to small scale differ throughout the Gulf; is fairly low (< 0.6 cm per 100 years; industrial as well as intense shipping activities from the commer- Lykousis and Anagnostou, 1992) in the center basin and high ∼ cial Piraeus Port, which is one of the biggest in the Mediterranean ( 0.30 cm per year; Hatzianestis et al., 2004; Eleftheriou et al., Sea, are still very present. As a consequence, the area is still being 2018) near the coastal areas. subjected to considerable pollution stresses. Two recent sedimen- The northern part of the Saronikos Gulf represents an intrigu- tological and geochemical studies of the surface sediments of the ing marine environment, significantly influenced by anthropogenic Drapetsona–Keratsini coastal zone by Kapsimalis et al. (2013, 2014) pressures due to its proximity to the metropolitan city of Athens. have revealed extremely high concentrations of heavy metals and The soft bottom consists of sandy and muddy sediments. The water ◦ organic compounds at levels of threat for the marine environment. temperature shows typical seasonal variation, ranging from 15 C ◦ Recently Dimiza et al. (2016b) studied the living foraminiferal to 24 C, while salinity is approximately 38–39 psu throughout the distribution at a network of 10 stations in Inner Saronikos Gulf year. The area is not affected by significant freshwater runoff. sediments. Based on benthic foraminifera data and the ecological quality classification tool, Foram Stress Index (FSI), classified the 3. Material and methods western and central part of Gulf as moderate environment status and the coast of Salamis and the eastern sector were characterized 3.1. Sampling sites and sediment abiotic parameters by more diversified epiphytic foraminiferal assemblage as good quality environment. This study focuses on the Drapetsona–Keratsini coastal zone, The present paper investigates the species composition, density which includes the rocky coast of Drapetsona, the bays of Sfageion and diversity of the benthic foraminiferal assemblages occurring in and Foron, the Akrokeramos Harbour, the Drapetsona quay wall the environmentally degraded Drapetsona–Keratsini coastal zone and the Keratsini Port (Fig. 1). Surface sediment samples (up to and attempts to determine the assemblage response in relation to 2 cm thick) were collected from 12 locations (KER1–KER12, see the local abiotic characteristics of the sediments, such as texture, Fig. 1 and Table 1), at water depths of 8–29 m, in December 2012, organic carbon content, hydrocarbon and heavy metal concentra- using an Ekman grab sampler. According to the local sedimenta- tions. tion rate (∼0.30 cm per year; Hatzianestis et al., 2004; Eleftheriou et al., 2018; Hatzianestis et al., 2004; Eleftheriou et al., 2018) the 2. Study area sampled sediment represents approximately six years of accumu- lation. At each sampling site, the sediment texture (Table 1) as well The area under investigation is located in the northern part as inorganic and organic sediment components, comprising heavy of the Saronikos Gulf (Fig. 1), which is a neotectonic basin on the metals, aliphatic and polycyclic aromatic hydrocarbons and organic M.D. Dimiza et al. / Revue de micropaléontologie 62 (2019) 33–44 35 Table 1 general environmental conditions, paying attention to the possible Sampling location, depth and sediment nomenclature according to Folk (1974). influence of taphonomic processes (Morvan et al., 2006; Carboni Station Location Depth (m) Sediment type et al., 2009). KER1 Piraeus Port exit 15 Sandy silt KER2 Sfageion Bay 18 Silty sand 3.3. Data processing and statistical analyses KER3 Foron Bay 12 Sandy silt KER4 Akrokeramos Harbor 25 Silty sand For the data interpretation, species richness (S), as the num- KER5 Drapetsona quay wall 29 Silty sand ber of species in each sampling station, and