ESDIM: Searching the Past for Keys to the Future
SMAST scientists, in collaboration with Kenneth Sherman, Senior Biological Oceanographer and Chief of the Ecosystem Monitoring Branch of the Northeast Fisheries Science Center at NOAA, are participating in an Environmental Services Data and Information Management (ESDIM) project that includes searching the National Archives for the original records of the United States Exploring Expedition, the "Wilkes Expedition," of 1838-1842. The logs of Charles Wilkes' earlier 1837 survey of George's Bank and those of his Exploring Expedition that pertain to the northeast shelf region, are two elements of a larger collection that is being mined for oceanographic data, particularly sea temperature readings and plankton measurements, in an effort to extend the timeline of northeast shelf (NE shelf) oceanographic observations.
Researchers are using such historical data to detect climate change and predict the effects of climate change on fisheries productivity. Any shift in the ocean climate regime in the NE shelf region could impact the recovery of seriously depleted groundfish stocks, including cod, haddock and flounders. Researchers need to know the causes of these shifts in order to predict and prepare for them. "We are observing relatively rapid change in the ecosystem, " explains Dr. Brian Rothschild, SMAST Director. " In order to deal with that change we need to know if it is anthropogenic -man-made - or naturally occurring. One way we can do that is by developing a long database, which is what we are doing with ESDIM."
The paper records of nineteenth century oceanographic surveys in the northeast shelf region, and the paper logs of early researchers, lightship keepers and ship's mates, all contain data valuable to the ESDIM effort - data related to sea temperature and plankton, the two most readily available sources of information about marine climate. But examining these paper records is a tedious chore, conducted one record at a time, and some records are so fragile they are in danger of deteriorating beyond use. In addition, records are stored at several different locations, making collection and integration of the information an even more cumbersome task.
The SMAST ESDIM project is helping to solve these problems by searching out this early oceanographic date and transferring it to electronic format. Eventually, all the data will be accessible to scientists through the Marine Resources Monitoring and Assessment Program (MARMAP) database. ESDIM researchers are looking at several original sources for data. Although the Wilkes records provide the oldest data, the primary sources of temperature data are the measurements made by the Coast Survey vessels USS Bache, USS Bibb, USS Corwin, and USS Blake, between 1847 and 1880, and the US Fish Commission (precursor of the National Marine Fisheries Service) vessels Grampus, Fishhawk, Albatross, and Halcyon between 1880 and 1922. Temperature and plankton data has been recovered from data cards recorded by Henry Bigelow of Harvard University, for the years 1929-1941, and stored in the Woods Hole Oceanographic Institution's archives.
Additionally, monthly mean seawater temperatures have been collected from the records (1887-1956) of sixteen lightships along the east coast. Although the lightship data are not included in the ESDIM database because they are composite data (monthly means) rather than original observations, they provide good data for temperature time series analysis given the large number of observations - monthly means are based on twice-daily observations over many years.
Figure 1 provides an example of how this rescued data might be used to bring changes over time to the attention of researchers. It is a preliminary plot, prepared by David Borkman, now at the University of Rhode Island, using data from the Nantucket Shoals lightship (1878-1952) and the automatic buoy (NOAA #44008, 1983-1993) at the same location. The plot displays an apparent rise in the annual temperature range from ca. 2°C - 19°C annual range in 1880, to ca. 4°C - 21°C annual range from 1983 to 1993. Such changes in temperature in the northeast shelf region can have significant impacts on the fisheries. The potential value of this historical data is also indicated in a preliminary evaluation of the zooplankton data for Georges Bank. An initial analysis detected a change in zooplankton community composition and abundance.
As shown in Figure 2 (prepared
by Russell Hopcroft of the University of Alaska Fairbanks), initial
comparisons of past (data of Bigelow, ca. 1940) and present (MARMAP
data, 1975 to
present) abundance of major zooplankton groups show differences in both
the timing and size of zooplankton annual cycles. For example, in June
1940-1941, Pseudocalanus abundance was nearly four times greater than
the MARMAP mean. The data collection phase of the SMAST ESDIM project
is continuing. To date, more than 27,000 observations from 1925 or earlier
have been compiled. Most of these observations, nearly 19,000, are from
off the east coast of North America and all are believed to be absent
from existing national databases. In addition, the zooplankton and phytoplankton
data collected by Bigelow have been converted to standard units of organisms
per volume seawater, to make analysis easier.
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