334 MARINE BIOTIC COMMUNITIES 



Macoma-Astarte Community (Biome) 



This is an arctic ocean community with relicts farther south which 

 Spiirck (1935), who calls it the Macoma calcaria community, de- 

 scribes in the following terms: "This community is characterized by 

 the occurrence of Macoma calcaria as the constantly predominating 

 species. Beside this species, forms such as Astarte borealis, ellip- 

 tica, montagui, Portlandia, Yoldia hyperborea, Nucula tenuis, Leda, 

 etc., may occur; also Nephthys ciliata, species of Pectinaria and Har- 

 mothoe, Oyniphis conchylega and several other Polychaeta have been 

 found. Among echinoderms, Myriotrochus rinki and Ophiocten seri- 

 ceurn are the most frequent. This community has been described 

 from the coasts of the East Greenland fjords (Thorson, 1933, 1934; 

 Spiirck, 1933), where it seems to occur everywhere on clay bottoms 

 and on sand mixed with clay. It occurs in different locally and bathy- 

 metrically determined varieties. The lower limit of this community in 

 the East Greenland fjords is about 50 meters. Outside the East 

 Greenland fjords this community has been described from various 

 other arctic waters, namely the Storfjord in Spitzbergen (Brotzky, 

 1931), where this community is present in the inner part of the fjord, 

 on soft bottoms near the Spitzbergen Bank (Idelson, 1931), in the 

 waters near the Kanin Peninsula (Zenkevitsch, 1931), in parts of the 

 Barents Sea, in the White Sea (Zenkevitsch, 1927), and northern 

 Norway (Soot-Ryen, 1924). In the Barents Sea it occurs at greater 

 depths than in the East Greenland waters, down to 100-150 meters. 

 The Macoma calcaria community occurs at Iceland and the Faroes 

 (Sparck, 1929)." The fragments in the Baltic are regarded as relicts 

 (Fig. 76). 



Macoma-Mya Community (Biome) (Petersen's Macoma Community) 

 in the North Atlantic (Fig. 75) 



It occurs slightly above mean low tide to 20 meters' depth in the 

 Baltic. The outstanding bivalves are Mya arenaria, Macoma bal- 

 thica, and Cardium edide, polychaete worms, Arenicola marina, Aricia 

 and Nephthys. Blegvad (1916) divides the community into three 

 parts, essentially based upon dcptlis. We have ventured to call these 

 faciations in accordance with the facts brought out on page 247. 



The Mya-Cardium-Arenicola faciation occurs in the shoreward 

 side of the Zostera. This is frequented by fishes such as sticklebacks 

 and is the breeding place of gobies, each at the proper season. Blegvad 

 does not record a barnacle-gastropod-mussel community such as is 



