NUMBER 40 . 3 



Clathromorpbum circumscription is the most widely dis- 

 tributed member of the genus, ranging from Hokkaido, Japan, 

 and British Columbia (Adey et al., 1976; Lebednik, 1976) in the 

 North Pacific through the Arctic to the southern Gulf of Maine in 

 the western Atlantic and Iceland and the Norwegian fjords south 

 to Trondheimsfjord (Adey, 1965, 1971) in the eastern Atlantic. 

 Restricted largely to intertidal pools and the shallow sublitto- 

 ral, C. circumscriptum can (rarely) achieve 5-10 cm in thick- 

 ness. However, both the conceptacles and the intraconceptacle 

 vegetative crust in this species always break out at reproductive 

 maturity, considerably disrupting thallus layering. Together with 

 a tendency to experience greater environmental disturbance, it is 

 a possible, but generally poor, subject for climate archiving. 



Clathromorpbum compactum, a cold-water carbonate 

 builder and a primary subject of this volume, extends from north- 

 eastern Hokkaido, Japan, through the Arctic to the central Gulf 

 of Maine in the western Atlantic (Adey et al., 2008) (Figure 1). 

 Clathromorpbum compactum is not reliably known from Iceland 

 or Norway, occurs in deeper water, and is conspicuously more 

 limited to colder water than C. circumscriptum (Adey, 1965; 

 Adey et al., 1976). Adey et al. (2008) treated C. compactum as 



an Arctic species, although it is more likely Subarctic in origin 

 and distribution. Although collection sites in the Arctic are only 

 scattered, Clathromorpbum compactum is generally an abundant 

 species wherever it is found, and rock substrate, coastal salinity, 

 and a high sediment load are not limiting. 



Clathromorpbum uereostratum (Figure 1) and Clathromor- 

 pbum loculosum are cor-strome formers and appear to be largely 

 restricted to the Aleutian Islands; both species are reported for 

 the Asian mainland coasts, but insufficient definitive work has 

 been carried out in the Okhotsk and western Bering Seas to deter- 

 mine whether they are significant components of the algal flora. 

 Clathromorpbum loculosum has a leafier growth morphology 

 (Lebednik, 1976), and its archival potential is unknown. Clath- 

 romorpbum uereostratum is the most massive of the Clathro- 

 morpbum species, largely because of its Subarctic-Boreal fringe 

 environment in the Aleutian Islands. Clathromorpbum uereo- 

 stratum and C. compactum are conspicuously layered, often 

 with buried conceptacles, and provide the greatest opportunities 

 for climate archiving. Both the Arctic and the northeastern Asian 

 mainland and its off-lying islands provide a largely unknown and 

 potentially rich region for cor-strome climate archiving. Here we 



FIGURE 1. Known geographic distribution of principal Clathro/tiorpbum clathrostrome formers. 

 Clathromorpbum uereostratum has been reported from the mainland coast of easternmost Asia, 

 but records need to be verified. 



