An Arctic Kelp Community in the Alaskan Beaufort Sea

• Published in: Arctic 1982-01, Vol.35 (4), p.465-484
• Main Authors: Dunton, Kenneth H., Reimnitz, Erk, Schonberg, Susan
• Format: Article
• Language: English
• Subjects: Algae; Biota; Boulders; Cobbles; Ice; Laminaria solidungula; Marine; Ocean floor; Plants; Rocks; Seas; Sediments
• ISSN: 0004-0843; 1923-1245
• DOI: 10.14430/arctic2355

The discovery of the "Boulder Patch", an area of cobbles and boulders with attached kelp and invertebrate life, is reported from Stefansson Sound, near Prudhoe Bay, Alaska. Geophysical surveys using side-scan sonar and low-frequency recording fathometers revealthat cobbles and boulders occur in patches of various sizes and densities. Despite a seasonal influx of sediments, the Boulder Patch is a nondepositional environment. Physical disruption of cobbles and boulders by deep draft ice is minimal due to offshore islands and shoals which restrict the passage of large ice floes into Stefansson Sound. The apparent absence of similar concentrations of rocks with attached biota along the Alaskan Beaufort Sea coast is explained by the scarcity of rocks in areas protected from ice abrasion and with no net sediment deposition. In Stefansson Sound, the rocks provide a substratum for a diverse assortment of invertebrates and several species of algae. Recolonization by the biota was minimal on twelve boulders denuded and then left undisturbed for a three-year period. Sedimentation and grazing activity appear to be the major factors inhibiting recolonization. Linear growth in the kelp, Laminaria solidungula, is greatest inwinter and early spring when nutrients are available for new tissue growth. The plant draws on stored food reserves to complete over 90% of its annual linear growth during the nine months of darkness under a turbid ice canopy. These reserves are accumulated by photosynthetic activity during the preceding summer. The total carbon contribution made by kelp in Stefansson Sound under these conditions is about 146 x 10⁶ gyr⁻¹ or 7 gm⁻¹ yr⁻¹.A small percentage of this carbon is consumed directly by herbivores, but its importanceto other organisms is not known and is under investigation. /// L'article rapporte la découverte d'un terrain couvert de grosses pierres et de galets sur lesquels vivent du varch et des invertébrés, au détroit de Stefansson, près de la baie Prudhoe, en Alaska. Deslevées géophysiques de ce terrain nommé "Boulder Patch", effectuées à l'aide de sonars àbalayage latéral et de fathomètres à basse fréquence, ont indiqué que les grosses pierres et les galets sont groupés en ensembles de diverses dimensions et densités. Même à l'augmentation saisonnière de sédiments, il n'y avait aucune accumulation de ces sédiments sur le terrain en question. Le dérangement physique des pierres et galets par les glacesprofondes est minime grâce aux îles mar