Bodini et al. – Dominator trees and secondary extinction
THE BARENTS ECOSYSTEM FOOD WEB
The Barents eco-region and its food web
The Barents Sea eco-region is a shelf area of approx. 2.2 million km2; it is situated in
the transition zone between European boreal and European arctic region. It is a typical
spring bloom system. Primary production is favoured at the ice edge, where, in
autumn and winter, a vertical mixing of water masses brings deep sea nutrients to the
surface layers. In spring and summer, melting ice stabilizes the nutrient-enriched
water column, creating a layer where phytoplankton production is not affected by
vertical mixing. As the melting ice edge retreats, nutrient-rich waters are exposed to
light and this favours algal blooms. During these phases algal species diversity is not
very high but primary production is reaching 90 gC/m2. Diatoms (half of the species
inventory) and flagellates dominate the phytocoenosis.
Zooplankton is dominated by arctic-boreal organisms, in particular the Calanus
species, which feed preferentially on diatoms. Krill is another important component of
the food web and the most common species belong to the genus Thyssanoessa.
Zooplankton and krill act as a link between phytoplankton (primary producers) and
fish, mammals and other organisms at higher trophic levels. The most numerous fish
species are cod (Gadus morhua), capelin (Mallotus villosus), herring (Clupea
harengus) and polar cod (Boreogadus saida). They constitute the core of biological
production in the area and give rise to complex ecological interactions. Cod, the most
important predator in the Barents Sea, preys on capelin, herring and smaller cod,
while herring prey on capelin larvae. Capelin feeds upon the zooplankton and it is the
most important prey species in the Barents Sea. Herring as well preys on zooplankton,
and it can reach the same importance as for abundance and energy content than
capelin.
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Bodini et al. – Dominator trees and secondary extinction
Large fish stocks, vast amounts of krill and other large zooplankton, and the amphipods
associated with subsurface sea ice sustain some of the largest seabird aggregations in the
world with more than 30 species. Four seabirds – kittiwake (Rissa tridactyla), Brünnich's
guillemot (Uria lomvia), little auk (Alle alle) and puffin (Fratercula arctica) - make up
nearly 85 percent of all breeding seabirds in the region. Marine mammals, as top predators,
are significant ecosystem components. About 24 species of marine mammals regularly
occur in the Barents Sea, comprising 7 pinnipeds, of which harp seal (Phoca
groenlandica) is the most abundant population, 12 large cetaceans (large whales) and 5
small cetaceans (porpoises and dolphins). This brief description gives a perception of the
complexity of the food web of this eco-region. Papers and reports carrying information
concerning the feeding habits of the species (see Dolgov 2002, Larsen et al. 2004; Cianelli
et al 2005; Stiansen et al. 2006 and references therein) were used to reconstruct the food
web. It is comprised of 151 nodes (species and trophospecies) excluding the root node, and
1035 links. With reference to Figure 2 and 3 in the main body of the article, the
correspondence between nodes and species is as follows:
R: root; 1.Phytoplankton, 2.Macroalghe, 3.Detritus, 4. Calanus glacialis, 5. Calanus
hyperboreus, 6. Calanus finmarchicus, 7. Apherusa glacialis, 8. Onisimus nanseni, 9.
Onisimus glacialis, 10. Gammarus wilkitzkii, 11. Metridia longa, 12. Euchaeta norvegica,
13. Euchaeta glacialis, 14. Pseudocalanus spp., 15. Oithona similis, 16. Microcalanus
pusillus, 17. Thysanoessa raschii, 18. Thysanoessa inermis, 19. Thysanoessa
longicaudata, 20. Meganyctiphanes norvegica, 21. Themisto abyssorum, 22. Themisto
libellula, 23. Cucumaria frondosa, 24. Paralithodes camtschaticus, 25. Balanus sp., 26.
Sabinea septemcarinata, 27. Pontophilus norvegicus, 28. Munida sp., 29. Ophiocantha
bidentata, 30. Ophiura sarsi, 31. Ophiura albida, 32. Ophiura robusta, 33. Ophiopholis
aculeata, 34. Ciliatocardium ciliatum, 35. Pagurus pubescens, 36. Aurelia aurita, 37.
Aglanta digitale, 38. Sarsia princeps, 39. Euphysa flammea, 40. Mertensia ovum, 41.
Bolinopsis infundibulum, 42. Sagitta elegans, 43. Limacina helicina, 44. Limacina
retroversa, 45. Mytilus edulis, 46.
Strongylocentrotus droebachiensis, 47. Asterias
Rubens, 48. Crossaster papposus, 49. Appendicularian tunicates, 50. Gonatus fabricii, 51.
Bathypolypus arcticus, 52. Todarodes sagittatus, 53. Pandalus borealis, 54.
Sclerocrangon boreas, 55. Hyas araneus, 56. Amblyraja radiata, 57. Amblyraja
hyperborea, 58. Rajella fyllae, 59. Dipturus batis, 60. Bathyraja spinicauda, 61. Dipturus
linteus, 62. Dipturus oxyrhyncus, 63. Leucoraja fullonica, 64. Lamna nasus, 65. Squalus
acanthius, 66. Gadus morhua, 67. Melanogrammus aeglefinus, 68. Hippoglossoides
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Bodini et al. – Dominator trees and secondary extinction
platessoides, 69. Reinhardtius hippoglossoides, 70. Sebastes mentella, 71. Sebastes
marinus, 72. Pollachius virens, 73. Micromesistius poutassou, 74. Mallotus villosus, 75.
Clupea harengus, 76. Boreogadus saida, 77. Pleuronectes platessa, 78. Limanda limanda,
79. Eleginus navaga, 80. Ammodytes sp., 81. Anarchicas lupus, 82. Anarchicas minor, 83.
Anarchicas denticulatus, 84. Ciclopterus lumpus, 85. Trisopterus esmarkii, 86. Argentines
sp., 87. Sprattus sprattus, 88. Salmo salar, 89. Salmo trutta trutta, 90. Fulmarus glacialis,
91. Morus
bassanus, 92. Phalacrocorax carbo, 93. Phalacrocorax aristotelis, 94.
Somateria mollissima, 95.Somateria spectabilis, 96.Clangula hyenalis, 97. Stercorarius
parasiticus, 98. Larus canus, 99. Larus argentatus, 100. Larus marinus, 101. Alca torda,
102. Rissa tridactyla, 103. Uria aalge, 104. Uria lomvia, 105. Cepphus grylle, 106.
Fratercula arctica, 107. Sterna paradisea, 108. Gavia stellata, 109. Gavia artica, 110.
Mergus serratus, 111. Charadrius hiaticula, 112. Calidris marittima, 113. Calidris
alpina, 114. Larus hyperboreus, 115. Alle alle, 116. Haematopus ostralegus, 117.
Phagophila eburnea, 118. Delphinapterus leucas, 119. Balaenoptera acutorostrata, 120.
Balaenoptera borealis, 121. Balaenoptera physalus, 122. Balaenoptera musculus, 123.
Balaena mysticetus, 124. Eubalaena glacialis, 125. Megaptera novaeangliae, 126.
Monodon monoceros, 127. Physeter macrocephalus, 128. Delphinus delphis, 129. Orcinus
orca, 130. Lagenorhynchus albirostris, 131. Lagenorhynchus acutus, 132. Tursiops
truncatus, 133. Hyperoodon ampullatus, 134. Phocoena phocoena, 135. Lycodes
reticulatus, 136. Lycodes esmarkii, 137. Gaidropsarus argentatus, 138.
Artediellus
atlanticus, 139. Triglops murrayi, 140. Odobenus rosmarus, 141. Erignatus barbatus, 142.
Phoca hispida, 143. Phoca groenlandica, 144. Phoca vitulina, 145. Cystophora cristata,
146. Halichoerus grypus, 147. Somniosus microcephalus, 148. Ursus maritimus, 147.
Pagophilus groenlandicus, 150. Anas crecca, 151. Liparis gibbus
Literature Cited
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Ulanowicz), pp.143-169. Oxford: University Press
Dolgov, A. V. 2002 The role of capelin (Mallotus villosus) in the foodweb of the Barents Sea. Journal
of Marine Science 59, 1034–1045.
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Bodini et al. – Dominator trees and secondary extinction
Larsen, T., Nagoda, D., & Andersen, J. R. 2001 The Barents Ecoregion. A biodiversity Assessment,
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