Environmental response of living benthic foraminifera in Kiel Fjord, SW Baltic Sea A. Nikulina, I. Polovodova, J. Schönfeld To cite this version: A. Nikulina, I. Polovodova, J. Schönfeld. Environmental response of living benthic foraminifera in Kiel Fjord, SW Baltic Sea. eEarth Discussions, 2007, 2 (4), pp.191-217. hal-00298257 HAL Id: hal-00298257 https://hal.archives-ouvertes.fr/hal-00298257 Submitted on 3 Dec 2007 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. eEarth Discuss., 2, 191–217, 2007 eEarth www.electronic-earth-discuss.net/2/191/2007/ Discussions eED © Author(s) 2007. This work is licensed 2, 191–217, 2007 under a Creative Commons License. eEarth Discussions is the access reviewed discussion forum of eEarth Living benthic foraminifera in Kiel Fjord, SW Baltic Sea A. Nikulina et al. Title Page Environmental response of living benthic Abstract Introduction foraminifera in Kiel Fjord, SW Baltic Sea Conclusions References Tables Figures A. Nikulina, I. Polovodova, and J. Schonfeld¨ ◭ ◮ Leibniz-Institute for Marine Sciences IFM-GEOMAR, Wischhofstr. 1-3, 24148 Kiel, Germany ◭ ◮ Received: 1 November 2007 – Accepted: 22 November 2007 – Published: 3 December 2007 Back Close Correspondence to: A. Nikulina ([email protected]) Full Screen / Esc Printer-friendly Version Interactive Discussion EGU 191 Abstract eED The living benthic foraminiferal assemblages in the Kiel Fjord (SW Baltic Sea) were investigated in the years 2005 and 2006. The faunal studies were accomplished by 2, 191–217, 2007 geochemical analyses of surface sediments. In general, sediment pollution by copper, 5 zinc, tin and lead was assessed as moderate in comparison with levels reported from Living benthic other areas of the Baltic Sea. However, the inner Kiel fjord is still exposed to a high foraminifera in Kiel load of metals and organic matter due to enhanced accumulation of fine-grained sed- Fjord, SW Baltic Sea iments in conjunction with a concentration of pollution sources as shipyards, harbours and intensive traffic. The results of our survey showed that the dominant environmen- A. Nikulina et al. 10 tal forcing of benthic foraminifera is nutrients availability coupled with human impact. A comparison with data from the 1960s revealed apparent changes in species com- position and population densities over the past decades. The stress-tolerant species Title Page Ammonia beccarii invaded Kiel Fjord whereas Ammotium cassis disappeared, possibly Abstract Introduction due to low salinity that prevailed 10 years ago. These changes in foraminiferal com- 15 munity and a significant increase of test abnormalities indicate enforced environmental Conclusions References stress since the 1960s. Tables Figures 1 Introduction ◭ ◮ Benthic foraminifera of the Baltic Sea and Kiel Bight were investigated since the ◭ ◮ 19th century (Mobius,¨ 1888). However, there is still lack of information concerning Back Close 20 foraminiferal distribution in the Kiel Fjord. The available data are scattered, general- ized or consider only the open Kiel Bight. Rumbler (1935) started systematically the Full Screen / Esc ecological observations on foraminifera in the Kiel Bight. In the following, Rottgardt (1952) distinguished three different foraminiferal assemblages in the Baltic Sea: ma- Printer-friendly Version rine, brackish-marine (fjords and shallow areas of the Kiel Bight), and brackish faunas. Interactive Discussion 25 But he investigated the total (living plus dead) assemblages as a systematic discern- ment between living and dead faunas by staining methods had not been established. EGU 192 A detailed taxonomical and ecological overview on benthic foraminifera in the Baltic Sea was provided by Lutze (1965), who also considered 5 stations in the Kiel Fjord. eED Wefer (1976) estimated the short-term dynamics of benthic foraminifera in the open 2, 191–217, 2007 Kiel Bight off Bokniseck. The benthic foraminiferal response to the 2004 spring bloom 5 was investigated by Schoenfeld and Numberger (2007a) in the same area. The ben- thic foraminiferal distribution in the Kiel Fjord has been left out of sight. During the 20th Living benthic century, this area has experienced a strong anthropogenic impact. In view of rising foraminifera in Kiel ecological problems, the environmental response of benthic foraminifera comes into Fjord, SW Baltic Sea focus of investigation. A. Nikulina et al. 10 A number of studies have addressed the foraminiferal reactions to environmental pa- rameters as oxygen, salinity, temperature, food availability (e.g. Alve and Murray 1999; Gustafsson and Nordberg 2001) and contamination by trace metals (e.g. Yanko et al., Title Page 1998; Debenay et al., 2001). Surprisingly, no clear relationships between contami- nant levels and foraminiferal community structures were recognized even in heavily Abstract Introduction 15 polluted environments. In situ and in vitro experiments revealed, however, a decrease of foraminiferal population density, reproduction capability, enhanced mortality of some Conclusions References species, and increasing frequency of test abnormalities under the high trace metal or Tables Figures hydrocarbon concentrations (Alve and Olsgardt, 1999; Ernst et al., 2006; Le Cadre and Debenay, 2006). ◭ ◮ 20 Aim of this study was (1) to describe the distribution of living (stained) benthic foraminifera in the Kiel Fjord, (2) to investigate the distribution pattern of main geo- ◭ ◮ chemical parameters from surface sediments, (3) to outline the level of pollution by Back Close trace metals, and (4) to assess the foraminiferal response to environmental changes. Full Screen / Esc 2 Study area Printer-friendly Version 25 Kiel Fjord is a 9.5 km long, N-S extending and narrow inlet of south-western Kiel Bight ◦ ′ ◦ ′ ◦ ′ ◦ ′ Interactive Discussion (54 19 –54 30 N; 10 06 –10 22 ,E). The Friedrichsort Sound divides the fjord into a southern, inner fjord with width to 250 m, and a northern outer fjord, which expands up EGU 193 to 7.5 km and passes into Kiel Bight (Fig. 1). The inner Kiel Fjord is mostly 10 to 12 m deep. A system of up to 16 m deep channels connects the inner with the outer fjord. eED The outer fjord itself is more than 20 m deep. 2, 191–217, 2007 As the entire Kiel Fjord is relatively shallow and isolated, its hydrographic charac- 5 teristics weakly depend on the salt-rich inflow water from the Belt Sea. The only river debouching into Kiel Fjord is the Schwentine. Living benthic The water masses of the inner fjord are homogenously mixed, except during sum- foraminifera in Kiel ◦ mer. Then, surface water has temperature up to 16 C and a salinity of about 14 units. Fjord, SW Baltic Sea ◦ The underlying deep water has a temperature of about 12 C and salinity of up to 21 A. Nikulina et al. 10 units. In winter, the temperature – depth distribution is uniform and may be as low as ◦ to 2 C. The salinity is constant with depth as well (Schwarzer and Themann, 2003). Pleistocene till is eroded at cliffs and on the shoals of Kiel Fjord. The coastal and Title Page near-shore erosion is the most important source of sediment in this area. The sediment transport is mainly directed from north to south into the fjord. Lag sediments with Abstract Introduction 15 coarse sand and gravel prevail in the shallow coastal areas. They pass into sandy muds and silts in the deeper basins. In the innermost fjord, dark organic-rich muds Conclusions References are encountered even at shallow areas. Sand veneers are found in the Friedrichsort Tables Figures Sound due to relatively strong currents between inner and outer fjord (Schwarzer and Themann, 2003). ◭ ◮ 20 Kiel Fjord has seen an anthropogenic impact for the last 70th years by town in- frastructure, shipyards, military and sport harbours and the intense traffic through Kiel ◭ ◮ Canal. The shipbuilding industry leads to substantial trace metal and oil pollution in Back Close places. Dredging to keep the seaways clear, and the ship traffic itself causes a strong redistribution and disturbance of surface sediments. Full Screen / Esc 25 2.1 Previous pollution surveys Printer-friendly Version A number of studies on hydrography, sediment and organic matter distribution and Interactive Discussion pollution in the Kiel Bight have been carried during the 1960s–1970s by the former Special Research Unit (SFB) 95 of Kiel University. For the last decades, the environ- EGU 194 mental situation in Kiel Bight has been documented by annual reports of the Institute for Marine Research (IOW), Warnemunde.¨ Some of these data are summoned in the eED Helsinki Commission proceedings. However, not many reports on the pollution of the 2, 191–217, 2007 Kiel Fjord itself are available despite the long-term anthropogenic load in this area. The 5 recent investigation of trace metals pollution is performed and coordinated by the Re- gional Environmental Protection Agency (LANU) of the Bundesland Schleswig-Holstein Living benthic (e.g. Haarich et al., 2003). Some measurements of metal concentrations have been foraminifera in Kiel made in Kiel Fjord in the frame of monitoring of the Kiel Bight by the IOW (e.g. Pohl et Fjord, SW Baltic Sea al., 2005). Oxygen distribution and eutrophication of the fjord was mentioned by Ger- A. Nikulina et al. 10 lach et al. (1984) and Schiewer and Gocke (1995). Rheinheimer (1998) and Kallmeyer (1997) outlined the history of pollution by organic compounds in fjord. Studies of trace metals in mollusks (ter Jung, 1992) and fish (Senocak, 1995) included Kiel Fjord as Title Page well. Recently, LANU investigated the distribution and effects of TBT on mollusks of Kiel Fjord (LANU, 2001).