The coralline genus Clathromorphum Foslie emend Adey
Biological, physiological and ecological factors controlling high magnesium carbonate formation and producing a precision Arctic/Subarctic marine climate archive
Adey, W., J. Halfar and B. Williams. 2013. The coralline genus Clathromorphum Foslie emend Adey: Biological, physiological and ecological factors controlling high magnesium carbonate formation and producing a precision Arctic/Subarctic marine climate archive. Smithsonian Institution Scholarly Press 40. Washington, D.C. ISSN-0196-0768
A distinctive rocky Subarctic Biogeographic Region, extending through the lower Arctic from the Labrador Sea to the Bering Sea, and characterized by a sublittoral savanna of patchy kelp with an invertebrate and algal-rich, reef-like substrate of biogenic calcium carbonate, has been described over the past decade. Created by coralline algae, species of the genus Clathromorphum being dominant components, the carbonate crust forms annual layers, reaching 10-50 cm thick and typically 100-200 years old. Geochemical analyses, including laser scanning mass spectrometry, have demonstrated ages exceeding 650-850 years.
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As we demonstrate, Clathromorphum has evolved a unique mode of double calcification, with high magnesium calcite crystals, that enhances long life and leads to a multifaceted climate archive. Growth rates are controlled by temperature, and carbonate density by light, both in turn determined by latitude and sea ice cover. Carbonate build-up and ultimate thickness are determined by local geomorphology and faunal interactions. We present models of calcification, growth and ecology, derived from extensive field and laboratory data, which relate to controlling environmental factors.
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During the past five years, samples of the genus Clathromorphum, from this Subarctic carbonate belt, have been used to build archives of marine climate, similar to arboreal dendrochronology on land. Anatomical and geochemical analyses have provided an archive of past temperature (Mg/Ca ratios) and salinity (Ba/Ca ratios) for the Labrador and Bering Seas. The intricate anatomical patterns described in this paper, written in calcite crystals, provide precision proxy water climate information and ecological history.
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The Labrador and Bering Seas are regions of rapid climate change and are crucial areas for marine research. Both regions are major drivers of northern Hemisphere climate and yet are poorly understood. As a dominant producer of a distinctive biogenic and climate archival carbonate, Clathromorphum has evolved unique cytological and anatomical structures, described and modeled for the first time in this paper. This genus holds significant promise for an understanding of past and future climate.