Between summer 1983 and winter 1984, razor clam populations in Washington state beaches declined by an estimated 95%, from about 20 million clams to below one million clams. A year later, pathologist Ralph Elston identified the likely culprit, a bacterial pathogen that he called nuclear inclusion X (NIX), which was infecting gill tissue of the clams. Surveys conducted by Dr. Elston and colleagues revealed that the pathogen was prevalent in most clams in state beaches throughout Washington and was not detected in clams from northern British Columbia or Cook Inlet, Alaska. Recently, the possible associations between NIX infections and clam mortality resurfaced because of poor survival in adult razor clams in beaches in Olympic National Park in northwest Washington. 

To investigate this question, researchers at the Prince William Sound Science Center, along with colleagues at the US Geological Survey's Western Fisheries Research Center and the Olympic National Park, have developed two new molecular tests to identify NIX infections in razor clams (published recently in Journal of Invertebrate Pathology). The first test uses an assay called quantitative polymerase chain reaction to quantify how much DNA of NIX is in a tissue sample. The second test uses a molecular probe that binds to NIX DNA in tissue and can be seen under the microscope. A new survey shows that NIX remains present in Washington State razor clams but was not detected in razor clams from Cook Inlet. Stay tuned for more results. Now that researchers have developed these powerful tools, they are doing more fine-scale investigations into the spatial patterns of infection and to determine if NIX is the cause of poor survival of clams in Olympic National Park.