The goal of this pilot study was to assess whether variations in the oxygen isotopic composition of the growth increments reflect fluctuations in annual and seasonal sea-surface temperature (SST), and if the carbon isotopic composition can be used as a proxy for variations in productivity. Sclerochronological analyses of growth increments indicate that the rate of growth is positively correlated with temperature (Noakes and Campbell, 1992 Strom et al., 2004). The clams deposit well-defined annual growth lines within their shell each winter. Geoducks ( Panopea abrupta) are long-lived (>100 years), large subtidal clams native to the Pacific coast of North America, and especially abundant from Puget Sound to southeast Alaska. Preliminary analysis of carbon isotopic data on both the annual and seasonal timescales indicate the potential for assessing productivity changes in ambient seawater. Intra-annual sampling of annual growth increments indicates that the shells also appear to be recording seasonal changes in sea-surface temperature. The annual average oxygen isotopic values from two geoduck clams, whose first years of growth correspond to the early historic instrumental record (∼AD 1920) appear to be recording trends in sea surface temperature. The isotopic record is compared to the historic instrumental record as well as the thickness of geoduck growth increment measurements, which were also correlated with water temperature. The geoducks used in this study were collected in AD 2000 from west of Protection Island, located at the eastern end of the Strait of Juan de Fuca. Shells were sampled by thin-section from the hinge plate region, where the first 20–30 years of growth provide relatively wide annual increments suitable for sampling for isotopic analysis. Geoducks are long-lived and deposit annual growth increments within their shell each winter, making them potentially excellent paleoceanographic archives. Farming techniques are under scrutiny for their possible negative environmental impact.We tested the suitability of using Panopea abrupta (geoduck) shells to evaluate changes in both annual and seasonal sea surface temperature. They are sold for their size appearance and weight. These clams were not fished commercially until the 1970s, but in recent decades a huge demand from Asian markets has developed, and the clams are now farmed as well as being harvested in the wild. As adults they have very few predators other than humans. The geoduck is both one of the largest clams in the world, and one of the longest-lived animals of any type. The shell of the clam ranges from 15 centimetres (5.9 in) to over 20 centimetres (7.9 in) in length, but the extremely long siphons make the clam itself very much longer than this: the 'neck' or siphons alone can be 1 metre (3.3 ft) in length.

Happy Wednesday! The geoduck is native to the west coast of North America. The common name may be derived from a Native American word meaning 'dig deep'. OCEAN DEFENDER - Hawaii - The geoduck pronounced 'gooey duck',scientific name Panopea generosa, is a species of very large, edible, saltwater clam in the family Hiatellidae.

Western geo duck