Gunnar Lauenstein and NCCOS’s Mussel Watch Project
NCCOS Scientist Gunnar Lauenstein recently headed up a major effort updating NOAA’s landmark Mussel Watch Status and Trends Report. Here he addresses questions about the key findings of the unprecedented report, outlines ways interested user groups can get the most out of the report in their particular regions, and explains key points derived from two decades of related research.
What, in a nutshell, are the national trends for the contaminants named in the report? Generally speaking, are conditions improving or getting worse?
GL: Many of the contaminants monitored by the Mussel Watch Program have decreased over the past 20 years. Decreasing concentrations on a national scale were found for butyltins, which were used as anti–fouling compounds on boats; PCBs (Polychlorinated biphenyls), which were industrial chemicals used in electrical components; and DDT (Dichloro–Diphenyl–Trichloroethane), a ubiquitous pesticide. Decreasing trends were also documented for other organic compounds and for some elements. Results can be found in the report: the Mussel Watch Program: An Assessment of Two Decades of Contaminant Monitoring in the Nation’s Coastal Zone.
The NCCOS Status and Trends Report contains a wealth of information, indexed in various ways. But can you walk us through how an official or member of the public might use the report to evaluation conditions locally?
GL: The report summarizes Program findings from the national level to the regional level, with specific monitoring sites’ results at the back of the report. This format allows those interested in the national picture, whether they are federal environmental managers or legislators, to access the information in a form they need. The regional data allow state and regional officials and organizations to have the data in a form of greatest use to them. For organizations and individuals wanting specific status and trends information for their area, site information can be found in the section of the report providing state–by–state findings.
The report states that it is the first ever national summary of Mussel Watch data? Why now, after 20 years, was the decision made to do a national summary?
GL: Twenty years is an important milestone in a monitoring program, when it is possible to determine possible long–term trends as a result of environmental regulations. Also because it now requires two years to complete one sampling cycle, a complete national perspective is attained only on a biennial basis.
Hundreds of scientific papers have been written using Mussel Watch data sets. What makes this report unique?
GL: This report provides the findings for a majority of the organic contaminants and trace elements determined by the Program in one place and in an easy–to–understand format. Scientific papers frequently focus on one contaminant or group of contaminants and in so doing are required to provide detailed methods descriptions. This report, in contrast, provides the findings of many studies.
Who exactly is the target audience for this report, and how are they using the data?
GL: This report was intended for those individuals and organizations that want access to a synopsis of national monitoring results for the Nation’s coasts and Great Lakes. These data have been used to confirm the success of legislation enacted to reduce environmental contamination; the results also indicate a few areas where more work is needed.
How should localities interpret data on contaminants? Should managers and members of the public be concerned if levels of a particular contaminant in their locales exceed national averages?
GL: Generally the results should be viewed as positive, including for those areas above the current national average for contamination. It is important to understand that even for many areas that contain high levels of contamination, when compared to the national average, these contaminant levels have generally been decreasing for the past 20 years. Frequently today’s high values were yesteryears’ national average. Areas where levels of organic contaminants or trace elements have been increasing with time of course need to be looked at more closely.
Data from this Program clearly demonstrate that environmental regulations have had the intended effect
Why the emphasis on mussels and oysters to assess ecosystem contamination? What, in simple terms, makes them an effective surrogate for measuring water quality?
GL: Mussels and oysters have a number of advantageous properties that make them useful as sentinel organisms. They do not metabolize contaminants such as those that result from spilled petroleum or the burning of fossil fuels. For this reason we can see what actual contaminants marine animals are exposed to. Because mussels and oysters filter–feed, using relatively large volumes of seawater, we obtain an integrated signature of water contaminants in the area of a monitoring site. Because these mollusks are sessile—that is, they remain is one place, so we can revisit the same location year after year in order to determine contaminant trends through time.
The report cautions against using its results alone to address shellfish consumption issues. Please explain.
GL: The Program’s mussel and oyster sites do not necessarily coincide with commercial and recreational shellfishing areas. Contaminant levels in the Program’s mussels and oysters in certain instances could therefore be lower or higher than concentrations found in adjacent shellfishing areas.
What does the report say about the effectiveness of nationwide programs aimed at reducing contaminant levels?
GL: Data from this Program clearly demonstrate that environmental regulations like those that banned the use of DDT and PCBs in the 1970s have had the intended effect, which is to improve the environmental condition of the Nation.
Does NCCOS also look at contamination of sediments and the water column? And if so, are those results consistent across separate sources?
GL: Mussels and oysters are really surrogates for water column contaminant measurements. Because mussels and oysters can concentrate contaminants, above concentrations found in the water, by up to 100,000 fold, they make monitoring possible. Also because mussels and oysters integrate contaminants through time, a longer–term perspective of site related contamination is possible. Mussels and oysters actively take food from the water column, and this active sampling and the movement of water over gill surfaces increases the likelihood the mussels and oysters will concentrate organic contaminants.
Furthermore, mussels and oysters have the ability to actively accumulate certain elements. For example oysters have the ability to concentrate copper to a greater degree than mussels, while mussels can concentrate chromium to a greater degree than oysters. Sediments do not actively sample their environment. Contaminants are generally proportional to the amount of surface area. So, in other words, the smaller the grain size generally the more surface areas that exists to which contaminants can bind.
The Mussel Watch Program also looks at sediment contamination, though the national sampling frequency is limited to once every ten years. Data are becoming available only now for this corresponding environmental compartment.
You report that the highest concentrations for metal and organic contaminants are found near urban or industrial areas? Were there any surprises?
GL: Generally the conclusion that metals and organic contaminants are correlated with population density holds true. But for certain elements such as cadmium upwelling of deep Pacific Ocean water on headlands, removed from population centers, can be the exception to this general view.
How has the Mussel Watch program been affected by the die–off of oysters, in the Chesapeake Bay Region for example?
GL: There have been sites in the Chesapeake Bay and along the Gulf Coast that can no longer be monitored because of either oyster die–off or because land subsidence/sea level rise have destroyed oyster habitat. The latter case is particularly true for sites that were located at the Mississippi River outlet.
What can you tell us about the histopathology component of Mussel Watch and how it may help in the future to assess the effects of climate change?
GL: Mussel Watch is frequently perceived as only a chemical monitoring program, but mussels and oysters are also characterized for incidence of disease and parasites. A multi–year record now exists for these conditions for samples collected concurrently, just as for the chemical characterizations. There is a correlation between disease incidence and water temperature or certain parasites and disease organisms that are limited by colder temperatures found further north. As the world’s oceans warm, we may see the spread of certain disease organisms in mussels and oysters.
Can you explain in lay terms the techniques the report uses to account for differences in how various species react to environmental contaminants?
GL: Overlapping species were collected at the same site in order to determine whether contaminant levels were comparable across species. We did this for oysters and mussels in Long Island Sound, and the result is that organic contaminants are nearly identical while mussels and oysters do concentrate certain metals differently including: copper, silver, zinc, chromium and lead.
Where can people turn for more detailed information on these issues? Is there access to the data behind the report—for those who wish greater specificity, and access to the detail data?
GL: Data can be accessed from our web site. Those needing assistance with more detailed data requests can call (301) 713–3028 ext. 152.