The Franklin-Folger Chart, c1769. Made by Benjamin Franklin
and his cousin Timothy Folger, a whaling captain and merchant, it was
the first chart to show the Gulf Stream. If a westbound ship entered the
Gulf Stream, it would be slowed by 60-70 miles a day, adding 2 weeks to
its journey. Biblioteque Nationale de France, Paris.
Figure 2.
Jack W. Jossi, Robert L. Benway, and Julien R. Goulet
NOAA, National Marine Fisheries Service
Bob Benway
received his initial training in marine science as a member of the United
States Coast Guard. He earned an AS (Electronics Technology) from the New
England Institute of Technology and has completed course work at the University
of Rhode Island and the Graduate School of Oceanography. Since joining NOAA
in 1972 he has been involved in the development and operation of NMFS's
Ships of Opportunity Program (SOOP) and oversees and coordinates all field
operations for SOOP and the MARMAP Ecosystems Monitoring Surveys. Julien
Goulet received a BS in earth sciences from Massachusetts Institute
of Technology, and earned an MS in physical oceanography from the University
of Rhode Island. He has been with NOAA and its predecessor agencies since
1965, designing and implementing database management systems and applying
statistical analyses to fisheries-oceanography problems.
The use of private, merchant, and military
vessels on an opportunistic basis to collect oceanographic and meteorological
information has a centuries-long history. Information was initially gathered
by people to help them make a living from the oceans. It was shared within
their communities and passed down through generations along with other
valuable cultural information. As the tools for using the oceans expanded,
so did the geographical range of the information being gathered. The evolution
of maritime commerce and exploration went hand in hand with an increasing
requirement for information about ocean currents, weather, and the location
of marine resources. This information was of great value and was fiercely
guarded against competing interests. The eighteenth century provided a
slight easing of this proprietary policy when Benjamin Franklin, then
Postmaster General, happened to discuss with Nantucket sea captain, Timothy
Folger, the sluggish nature of the delivery of mail from England to New
England. Folger explained that Gulf Stream information, well known to
his colleagues but rejected by the mail packet captains, would reduce
these trans-Atlantic crossings by two weeks. Franklin took advantage of
this information to improve the mail service and began a systematic, cooperative
collection of ocean current and temperature data that continues today.
By the middle of the nineteenth century, the US Navy Hydrographic Office,
under the command of Lt. Matthew Fontaine Maury, had compiled existing
information from mariners' log books and inaugurated a hydrographic reporting
program among ships' masters that led to the publication of the Wind and
Current Chart of the North Atlantic. Maury proposed exchanging this information
between maritime nations; his idea was enthusiastically adopted.
In 1925 the British scientist, Alister
Hardy, took his newly designed Continuous Plankton Recorder (CPR) (see
Fig. 1) to the Antarctic on the Discovery expedition.
His idea was to apply methods similar to those employed in meteorology
to study the changing plankton distribution, its causes and effects. In
1932, he began a survey using merchant vessels in the North Sea to collect
plankton at a standard depth of 10m. This survey has expanded to include
the entire North Atlantic. It is the longest and most extensive marine
plankton-monitoring database in existence.
An event in 1937 must be noted for its eventual
role in the use of volunteer observing ships. Athelstan Spilhaus (geophysicist,
inventor, first US ambassador to UNESCO, and Sea Grant visionary) developed
the mechanical bathythermograph used to obtain continuous tracings of
temperature versus depth in the surface layers of the ocean. This instrument
was the predecessor to the expendable bathythermograph which remains a
cornerstone in ships of opportunity sampling today.
With the formation of the National Oceanic
and Atmospheric Administration (NOAA) in 1970, the US and the United Kingdom
joined forces to extend the CPR survey into additional areas of the northwest
Atlantic. Together they worked to develop a new generation of CPR which
would continue the collection of biological data while also sampling the
upper layers of the ocean with sensors for measuring physical and chemical
characteristics of the environment. This partnership, represented in the
US by the NOAA-Fisheries Narragansett Laboratory near the URI Bay Campus,
has developed a new suite of ships of opportunity tools, such as the NuShuttle
(see Fig. 2). The formation of NOAA also enhanced collaboration between
the National Weather Service, the National Ocean Service, the US Maritime
Administration, and the National Marine Fisheries Service to use merchant
and other cooperating ocean-going ships for the collection of meteorological,
physical, and biological data along regular routes extending from the
United States coast. The geographical extent of this program, the sophistication
of instrumentation, the kinds of data collected, and the value to the
United States have all grown and should continue to do so. The program
is now under the organizational umbrella of NOAA's Volunteer Ocean Ships
(VOS) Program.
The NOAA-Fisheries
Narragansett Laboratory is a major participant in the VOS program, both
historically and scientifically. Monthly monitoring of ocean temperature,
salinity, phytoplankton, and zooplankton has been conducted between Boston
and Nova Scotia for nearly 40 years; between New York and Bermuda for
more than 28 years; near Georges Bank for six years (see Fig. 3). The
resulting data records are among the longest of their kind for the US
Atlantic coast. These time series play an essential role in NOAA's responsibility
as stewards of the coastal waters of the United States. They are used
to look at broadscale ecological and climatic variations, natural versus
anthropogenic changes, and to develop indices of ocean health for management
purposes to be used much the way economic indices are used. One important
project, now underway, seeks to determine how climatic temperature change
might alter the abundance and composition of lower food chain organisms.
Plankton abundance and temperature in the
Middle Atlantic Bight vary considerably throughout the year and from one
year to the next. We are examining how patterns in the annual and multi-annual
temperature are related to patterns of plankton abundance. Temperature
is well known to affect the growth, migration, reproduction, and metabolic
rates of marine organisms and is also the topic of intense research on
global climate change. Any changes in the timing and magnitude of plankton
cycles could have a significant impact on fish stocks which, at least
during their early life stages, depend on sufficient quantities of certain
plankton for their sustenance. For our research, we chose the early stages
of the planktonic copepod, Calanus finmarchicus. This organism
when full grown is slightly smaller than a grain of rice and, like all
plankton, is carried about by ocean currents. We chose it because, in
addition to being an important source of food for young fish, it has a
preference for slightly colder environments. The preference for colder
water is useful for analyzing the effect of changing temperature on planktonic
life. Figure 4 shows the average annual variation
in temperature and abundance of Calanus finmarchicus from samples
taken between 1978 and 1997. All values come from a depth of 10m below
the surface. The continental shelf (approximately the first 190km from
the coast to water depths of about 100m) and the continental slope (from
the edge of the shelf to the Gulf Stream) portions of our transect are
shown in Figure 3a. The temperature on the shelf is generally colder than
on the slope; both reach their annual minimum between March and April
and their maximum in August. Our samples show that young Calanus finmarchicus
begin the annual increase in abundance slightly before the coldest time
of the year and peak four to five months before the hottest. A second
pulse in abundance is seen in both water masses, the more prominent occurring
in October in the shelf water. Figure 5 shows
the temperature and abundance data over the two-decade period and provides
a useful perspective for examining multi-year trends, cycles, and relationships
between the two features. Unlike Figure 4, these features are portrayed
as departures above and below the long-term average (the zero line on
the y-axis) in units which have been standardized to emphasize their importance.
Further, because lower temperatures were expected to relate to higher
abundances of Calanus finmarchicus, the scale for plankton departures
on the right of the panels has been inverted. Both features in both water
masses exhibit multi-year cycles of increase and decrease. Except for
a few years in either water mass series, there are no consistent, shared
relationships between trends in water temperature and Calanus abundance.
This is to be expected because relationships in nature are rarely so simple.
However, it does suggest other approaches that may be effective. For example,
Figure 4 shows that on average Calanus finmarchicus abundance begins
a dramatic increase one month (in shelf waters) and at least two months
(in slope waters) before the temperatures begin their spring increase.
To successfully investigate the role of temperature on abundance, one
must understand how the organism increases its biomass when its food is
not yet plentiful. Or perhaps plankton populations are carried to the
Middle Atlantic Bight from other regions, such as the western Gulf of
Maine. And finally, our example combines conditions from the entire continental
shelf (nearly 200km wide in this study area) and ignores annual cycles
(see Fig. 4) that differ somewhat between very nearshore, midshelf, and
outer shelf waters. Fortunately, data gathered by ships of opportunity
permit us at the NOAA-Fisheries Narragansett Laboratory to ask and answer
these questions.
Acknowledgments
The authors wish to express their appreciation to the owners, officers,
and crews of the many private, military, government, and academic institutions
who, over the years, have contributed their efforts to make this program
possible.