The Danish Late Quaternary marine molluscs The record of shell-bearing Danish Late Quaternary Knudsen (1995). Furthermore, general information has marine molluscs has been established on the basis of been taken from Jensen & Spärck (1934), Lemche finds made during the systematic geological mapping (1948), Nordsieck (1968, 1969), Fretter & Graham since 1888, as presented in the publications from the (1976–1978, 1980–1982, 1984), Fretter et al. (1986) and Geological Survey of Denmark, mainly in the I. Række Poppe & Goto (1991, 1993) (which will not be quoted covering the descriptions for the map sheets. Further- throughout the text, listing the many species and their more, special papers on Holocene and Late Pleistocene environment). marine molluscs have been included. Most of them Only the synonyms mentioned in texts on Danish have been listed in one of the preceding chapters on molluscan finds are included. A list of these synonyms works on Danish sites with marine sediments. is found heading the Index of species. The investigations carried out by scientists in the 1. The Bælt Sea area northern Atlantic have given a good base for the evalu- 2. The Baltic Sea area ation of the Danish Late Quaternary molluscan fauna. 3. The Kattegat area with fjords These studies have been published mainly in papers 4. The Limfjord area on the Zoology of East Greenland, The Godthaab Ex- 5. The North Sea coastal area pedition 1928, the Zoology of Iceland, and the Zool- 6. The Vendsyssel area ogy of the Faroes. However, the Zoology of Green- 7. The Skagen area land has been supplemented by contributions from Macpherson (1971), Lubinsky (1980), the 6. og 7. Thule The regions are figured on the map (Fig. 2) and follow Expedition til Sydøstgrønland 1931–33 under the lead- the outline of the geological map sheets except the ership of Knud Rasmussen and the Treaarsexpeditionen Skagen area. It should be especially noted that the til Christian den X’s Land 1931–34 under the leader- southern limit during the Holocene of the North Sea ship of Lauge Koch. coastal region is at Blåvands Huk. Although this area In the two last-mentioned contributions, especially from Varde to the German border has been mapped, the animal ecology and the Arctic communities have no descriptions have been published. However, stud- been treated, which form a very important part in the ies of the Eemian from this region have been pub- discussion of the Danish Late Quaternary molluscan lished and will be commented upon when presenting assemblages. The following publications on molluscs the Eemian records from the above-mentioned areas. can be mentioned: The Bælt Sea area has been taken as the region between the Kattegat region and the Baltic, here fol- 1. From Greenland: Spärck (1933), Thorson (1933, lowing Ekman (1953) saying that the boundary be- 1944b, 1951), Thorson & Ussing (1934), Madsen tween the Bælt Sea and the Baltic proper is the thresh- (1936), Bertelsen (1937), Lemche (1941a, b), Ockel- old between Gedser and Darss and the southern end mann (1958), Kramp (1961, 1963). of the Øresund, see Fig. 1. 2. From Iceland: Spärck (1937), Lemche (1938), Thor- The reason for including the Øresund north of son (1941), Knudsen (1949a, b), Madsen (1949). Saltholm (northern and middle Øresund sensu Jensen 3. From the Faeroes: Lemche (1928), Thorson & Spärck & Knudsen 1995) in the Kattegat region is that regard- (1928), Spärck & Thorson (1931), Petersen (1968), ing the water from the Baltic the Øresund is a sound – Knudsen (1970). a passage – for the brackish water flowing north, but regarding the salt-water from the Kattegat, the Øre- As to the community concept as worked out by C.G.J. sund is a fjord down to the threshold between Amager Petersen, references have already been given to Peter- and Limhamn, to quote Thorson (1944a, p. 42). sen & Jensen (1911), Petersen (1913, 1914, 1915, 1918), The subfossil shell-bearing molluscs are presented and Thorson (1957). The regional division of the North- on the background of the annotated check list of re- ern European seas in to Arctic, Subarctic, Boreal and cent marine molluscs of Danish waters by Jensen & Lusitanian is from the zoogeographical division of the 24 GEUS Bulletin no 3.pmd 24 28-06-2004, 08:45 northern European seas as given by Feyling-Hanssen Fig. 6. Scissurella (1955, fig. 5) and Símonarson et al. (1998), as seen on crispata Fleming 1828. Figs 4 and 5 respectively. Anholt II, 78.06–78.09 m b.s. × 20. MGUH The molluscan genera and species are presented in 25316. groups within Class, Subclass and Order mainly fol- lowing the presentation of recent marine molluscs of Danish waters as given by Jensen & Knudsen (1995). When there is no subfossil record at hand the informa- tion is taken from the recent data as given by Poppe & Goto (1991, 1993), Jensen & Knudsen (1995) and oth- ers as listed previously. To facilitate the use of the index of all molluscan species, a list of synonyms is given as mentioned earlier including the species men- tioned in Danish mollusc literature. Class Polyplacophora Order Neoloricata Class Gastropoda Subclass Prosobranchia Among the seven species recorded in the recent Dan- Order Archaeogastropoda ish fauna only one, Tonicella marmorea, has been found subfossil in the Vendsyssel area from the Younger Scissurella crispata Fleming 1828 Weichselian deposits. It is a circumBoreal species which Fig. 6 in Europe is known from northern Scandinavia south to Denmark and recorded from around Iceland (Knud- Distribution. W Greenland, S and W Iceland, Spitsber- sen 1949a, b) down to Ireland (Poppe & Goto 1991). It gen, Norway north of Lofoten, and south to the Medi- is common in Danish waters, being known from the terranean. central part of the Kattegat and the Øresund region (Muus 1959), e.g. Subarctic–Boreal–Lusitanian species. Occurrence. The Subarctic (not in true Arctic water), Boreal and Lusitanian regions (according to Thorson Habitat. Common in shallow water of less than 20 m, 1941). otherwise recorded from 0–183 m (Muus 1959). The lack of information on subfossil finds may re- Habitat. In the waters around Iceland (Thorson 1941, flect difficulty in determination when the species is p. 4), the living specimens have often been found at found in the subfossil state of preservation with the depths greater than 500 m on clay bottom. However, shell parts apart. Polyplacophora do occur as seen from Poppe & Goto (1991, p. 64) write that the species lives the Skagen Well where finds have been recognised at on stones, shelly sand and clay bottoms between 15 the 70.10–70.30 m and the 37.0–37.25 m levels, viz. and 600 m. Fretter & Graham (1976, pp. 2–4) stated during the Subboreal and the Subatlantic respectively. that the species is always sublittoral, even in the ex- Among the other – only recent – finds of Polypla- treme northerly limits of its range, and occurs from 8– cophora, Leptochiton asellus is widely found from the 2000 m. It is not recorded from Danish waters although Arctic to the Lusitanian. Hanleya hanleyi, Ischnochiton Fretter & Graham mentioned it from the Norwegian albus and the above-mentioned Tonicella marmorea and Swedish coasts of the Skagerrak. are all found in the Subarctic, Boreal and Lusitanian regions. The last three species, Callochiton septemvalvis, Only subfossil finds. During the Eemian in the Kattegat Lepidochitona cinereus and Tonicella rubra, are all region. restricted to the Boreal–Lusitanian region. 25 GEUS Bulletin no 3.pmd 25 28-06-2004, 08:45 Patella vulgata Linnaeus 1758 Iothia fulva (Müller 1776) Distribution. Faeroes, Norway off the Lofoten islands, Distribution. Northern Scandinavia and S and W Ice- and south to the Straits of Gibraltar (Thorson 1941). land south to the Irish Sea, and like Lepeta caeca in deep water off the Azores. It is found in the Øresund Occurrence. Boreal–Lusitanian. region, but with rare and single finds in the Kattegat (Petersen 1888). Habitat. Intertidal, rocky shores or man-made hard substrates. However, it also occurs with seaweed. Only Occurrence. Boreal and Lusitanian. one recent individual has been found at Løkken, while empty shells are often found on the Skagerrak coast Habitat. Offshore between 5 and 600 m on hard sub- (Knudsen 1993). strates like Lepeta caeca. Subfossil finds. The Limfjord region, Holocene, in a Subfossil finds. The Limfjord region, Holocene. ‘køkkenmødding’ (kitchen midden) at Bulbjerg (Pe- tersen 1888). Acmaea tessulata (Müller 1776) Helcion pellucidum (Linnaeus 1758) Distribution. East Greenland, around Iceland (Thor- son 1941) and in Scandinavia according to Petersen Distribution. West and South Iceland, northern Nor- (1888). The Limfjord (Petersen 1986a). Common in the way north of Lofoten, and south to Portugal (Thorson Øresund, but absent in the Baltic. Extends southwards 1941). Also found in the Øresund, but absent from the to the north of the British Isles and Northern Ireland. Baltic and the Limfjord. Occurrence. Arctic, Subarctic, Boreal, and Lusitanian. Occurrence. Boreal and Lusitanian. Habitat. Lower part of the intertidal zone. In the south Habitat. Lives on seaweeds at depths from 0 to 27 m. connected with Zostera. Petersen (1888) points to this habitat as a reason why it is rarely found. Subfossil finds. The Limfjord region, Holocene. Subfossil finds. The Limfjord region and Vendsyssel, Acmaea virginea (Müller 1776) Holocene. Distribution. Northern Scandinavia and around Iceland Lepeta caeca (Müller 1776) (Thorson 1941), south to the Cape Verde Islands. Com- mon in the Kattegat and Øresund, but not found in the Distribution. From northern Scandinavia, N and S Ice- Baltic. land and Spitsbergen (Thorson 1941) south to Scot- land. It is not present in the Baltic, the North Sea and Occurrence. Subarctic, Boreal, Lusitanian. the Channel, but occurs in the Azores. This species, according to Poppe & Goto (1991), prefers cold tem- Habitat.