AN HISTORICAL OVER-VIEW OF RESEARCH AT THE MARINE INSTITUTE:
When the Marine Institute was first considered,
two questions were upper-most in the minds of the advisory committee;
what were the water flow characteristics and what was the importance
of the vast expanse of marsh? The early faculty appointments were
chosen with these questions in mind. Robert Ragotzkie and Theodore
Starr arrived in January 1954, fresh out of graduate school. They
were followed by Lawrence Pomeroy in September 1954. Ragotzkie's
role was that of hydrographer, studying water transport. Some time
later a short post-doctoral appointment brought Richard Dugdale to Sapelo,
where he worked with Ragotzkie on water flow and estuarine productivity questions.
Starr was appointed as microbiologist to study the bacteria, and Pomeroy’s
role was as a marine biologist, to study food webs and matters relating
to nutrients in the saltmarsh and water column. Starr remained
a year on the island, using the technique of measuring the amount of vitamin
B12 in the water as an indicator of the capacity of the system to support
the growth of algae. Further microbiological studies were undertaken
by Paul Burkholder from the Bacteriology Department of U. Ga. in Athens,
who encouraged the use of the island as a field site by students from
the main campus.
In June 1955, John Teal arrived.
As a graduate student he had been pursuing energy flow studies, whereby
estimates are made of the efficiency with which the ecosystem harnesses
and consumes energy. Not only was his research of great value
in expanding knowledge of how a saltmarsh functions, but his natural history
observations added depth to the information base gradually being accumulated.
He has written two books, co-authored with his wife Mildred, “Portrait
of an Island”, which is an account of seasonal changes and the natural
history of Sapelo, and “Life and Death of a Salt Marsh”, relating to the
environmental problems faced by the east coast saltmarshes.
The research conducted on Sapelo has
usually been directed towards field and environmental studies.
There is, however, one long standing and notable exception.
This is the elegant biochemical study of bioluminescence (so-called
“phosphorescence”), pursued since the 1950’s by Milton Cormier and
his colleagues at The University of Georgia. Renilla reniformis,
the sea pansy, found at low tide level on the beach, was used as his major
test organism in the search for the mechanisms involved.
John Hoyt and Vernon (Jim) Henry were
recruited in the early 1960’s, to bridge the geology information gap.
Both were sedimentologists, familiar with the transport of muds and
sands, which is so obvious a feature of Sapelo’s environment.
This was the start of a highly productive era for barrier island geology.
A series of cores, both on the island
and in the surrounding waters, provided clues to the relationship between
sea level variations and barrier island formation. It had been
assumed that the more recent (Holocene) islands such as Nannygoat and
Cabretta were formed from sands carried down to the coast by the rivers,
until the research of Orrin Pilkey showed that the sands originated (in
the most recent sense) from the continental shelf.
Robert Weimer and John Hoyt used fossil
ghost shrimp burrows to fix the heights of former sea levels and to
identify former beaches, a technique used and expanded in more recent
times by Robert Frey. James Howard used X-radiography to pinpoint
the textural changes in sediments as a result of the burrowing and foraging
behavior of bottom dwelling animals. By the late 60’s John Hails
and John Hoyt had refined and substantiated the barrier island – sea
level theory. In the process they showed that these phenomena are
dynamic and that the shorelines of barrier islands should be considered
mobile and flexible in a healthy system.
By the early 1960’s, methods of measuring
primary production (the conversion of light energy, via photosynthesis,
into usable carbohydrates), and factors regulating the process were
being elucidated by the work of Pomeroy, Odum and Schelske. These
methods are an invaluable means of assessing any environment.
Pomeroy's work on phosphorus pointed to the fact that the
absolute phosphorus concentration is not as important to the maintenance
of productivity as is the rate of turnover. In other words, if
phosphate is released by one organism and almost immediately used by
another, it is being efficiently used.
Ken Webb’s research was directed toward
the physiology of plants in a salt water environment. Saltmarshes
subject living matter to a number of stresses. There is a substantial
temperature variation between low and high tides, and many other differences
between growth in an aqueous environment contrasted with growth in an
atmospheric environment. Also when plants or bacteria have to take
in saline water to get the other nutrients they require, they then have
to expend energy to get the salt out of their tissues.
The investigations of Jack Payne and
his colleagues provided insight into the special requirements of
marine bacteria and their roles in the cycle of nitrogen.
In 1970 John Hoyt died in a glider accident.
His research had altered the whole understanding of the barrier island system
Within a short while, the Skidaway Institute
of Oceanography, located near Savannah, commenced operations.
It had the advantage of new facilities and a less isolated location.
Henry and Howard moved their base of operations to Skidaway, but still
maintained an interest in Sapelo. Their area of interest had
widened as time progressed. Henry was now becoming interested in
the development of capes and shoals along the south-east coast of the
United States and mapping the bottom features of the Georgia Bight.
Howard’s interest was directed towards trace fossils, fossil burrows
and ultimately, with De Pratter, archeological remains as a method of
dating former shorelines and sea-level variations.
Frey moved on to the faculty of The University
of Georgia in the early 70’s, meanwhile continuing research with
Howard on estuarine sediments. He was also involved in elucidating
the geological make up of saltmarshes.
There is an approach to large area ecology which involves
the use of high resolution aerial photography. Either conventional
color or black and white will provide information with regard to vegetation
changes, and infra red photography can be used to show details of water
flow patterns, tide height and diseased areas of vegetation.
Robert Reimold and Jack Gallagher used this approach to correlate aerial
photography with ground truth. Ground truth is exactly what it
says. Someone has to go in to the site pinpointed and see precisely
what is there in order to verify the usefulness of the photographic image.
Gallagher also made a large contribution to our knowledge of the production
and breakdown of halophytes (salt-tolerant plants). Reimold’s work
on phosphorus movement in Spartina has provided some insight into phosphorus
cycling in the marsh.
In 1967, William Wiebe joined the faculty
of the Microbiology Department in Athens. The saltmarsh/estuary
system at Sapelo has proved a constant challenge to him to the present
day. With Pomeroy, he embarked on a detritus study showing that
the number of bacteria on particles of detritus is very variable and
that this is largely indicative of the nutritive qualities of the particles.
Wiebe homed in on the fact that the microbial processes in the soil are
the key to saltmarsh productivity and to the availability of nutrients.
With co-workers such as Bob Christian, Graeme Skyring and Gary King, he
expanded Payne’s nitrogen work and encompassed the whole area of microbial
action and interaction in anaerobic soils, thereby gleaning information
on such processes as sulfur cycling and methane production.
In 1972 Lawrence Pomeroy and Dirk Frankenberg
received a three year grant from the National Science Foundation to
embark on a team effort to attempt to solve some of the remaining questions
with regard to the saltmarsh. This grant was followed by another
in 1975 to Pomeroy and Richard Wiegert. The approach used was
that of following a carbon model. Modelling is a method of quantifying
the contribution of all identified subsystems to the whole ecosystem
and the elucidation of all control systems applying to transfer between
those subsystems. Carbon is used because it is a readily monitored
variable, and also universal; all living matter is carbon based.
Atmospheric carbon dioxide is converted into carbohydrate by the activity
of plants and ultimately carbon dioxide is returned to the atmosphere
as the complex organic molecules are broken down. Any apparent discrepancy
in the flow of carbon through this cycle indicated a need for further
clarification by appropriate research. This six year study, with
twenty contributors, was published as a book in 1981.* [*”the
Ecology of a Salt Marsh” (1981). Ed L.R. Pomeroy and R.G. Wiegert Springer-Verlag.]
During the mid- to later seventies, investigations
were made by Alice Chalmers, Evelyn (Haines) Sherr, Barry Sherr and
Roger Hanson into the effect of treated sewage sludge, which is high
in nitrogen, upon the saltmarsh. The studies concluded that
such nitrogen load could be deleterious to the estuary if it were to
continue for a prolonged time. Chalmers’ current interests lie
with carbon and nutrient fluxes in coastal marine ecosystems, with
the exchanges of material between marshes and estuarine waters, and
in the dynamics of arsenic in thermal springs.
Evelyn Sherr has used stable carbon isotopes
which occur naturally to trace specific carbon pathways. With
various collaborators she has made a major contribution to our understanding
of the controversial questions concerning the relative importance of
algal and higher plant carbon in coastal food webs. At present,
the Sherrs are investigating the interactions of microprotozoans with other
components of the aquatic food webs and have developed a number of innovative
techniques for examining the trophic dynamics of heterotrophic nanoplankton
It was J(rg Imberger, a visiting hydrologist,
who provided the information on the hydrology of the Duplin River
which gave a key to sampling strategies for saltmarsh ecologists.
For example, rapidly used components such as ammonia should be sampled
at fixed sites, whereas slowly used components have to be followed in the
water mass over a period of time.
David Whitney’s research into algal productivity
was directed towards both phytoplankton and benthic diatom productivity
and how substantial a contribution is made by these microscopic components
of the system. Terrestrial and saltmarsh plants continue to
be E. Lloyd Dunn’s (Georgia Institute of Technology) major research
interest. Both the saltmarsh and dune habitats place stresses on plants.
To counteract the stresses, these plants have adapted physiological mechanisms
for survival and the efficiency of these mechanisms is the basis of his
research. One of Dunn’s graduate students, Robert Guirgevich, worked
with him in elucidating seasonal variations in the productivity of marsh
plants. Marshall Darley has been involved with algal productivity
questions, especially desiccation resistance, and worked with Whitney and
Dunn in areas of mutual interest.
The fiddler crab, Uca pugilator, was
a challenging organism for J. Roy Robertson. Robertson’s investigations
showed that there were chemical factors to which the crabs were sensitive
and which influenced their foraging patterns. The work on chemical
cues was continued with the ghost crab by a graduate student working
with Robertson, Tom Trott.
In the marsh, the bacterial and fungal
invasion of dead Spartina is important to the passage of nutrients
into animal food chains. Steve Newell has assessed the relative
roles of the fungi and the bacteria, and has developed biochemical techniques
for determining the microbial biomass within decaying Spartina.
Newell has gone on to define the importance of wetting in the degradation
of Spartina by fungi and continues to develop new techniques for analyzing
the productivity of fungal and bacterial communities.
Charles Hopkinson approached the question
of nutrient availability and recycling by comparing the strategies
used by freshwater plants to obtain nutrients with strategies of plants
in saline environment. While freshwater plants are profligate in their
use of nutrients, saltmarsh plants are conservative, even to the point
of recycling within the plant itself. Hopkinson’s major research
interest now lies in the evaluation of “outwelling” to the nearshore
zone and in attempting to follow the flow of lignin and carbohydrate
“biomarkers” through the saltmarsh estuary. This latter effort is also
of interest to Robert Hodson of the University of Georgia, who in collaboration
with Ron Benner, Mary Ann Moran and Newell, has looked at the dynamics
of lignin alteration in freshwaters, the estuary, and nearshore coastal
Robert Fallon was concerned with the
role of microbial metabolism in the cycling of carbon, minerals, and
energy. His work bridged the research areas covered by Hopkinson
and Newell. Fallon was particularly interested in elucidating sulfur
biogeochemistry, an area also considered by visiting scientists Skyring,
Howarth and King. The sulfur cycle has proven to be very important
in the generally oxygen deficient environments of the saltmarsh and
nearshore sediments. Current studies of volatile sulfur compounds
by Ron Kiene are providing a measure of these significant “global warming”
gases, which are produced in the marsh environment.
Ron Kneib’s research encompasses interactions
between predators and their prey and the influence of comparative
size on such interactions. His other interests include saltmarsh
food webs and the “export” of such animals as shrimp from the estuarine
environment to the nearshore zone thus contributing to “outwelling.”
His recent studies are beginning to determine the “carrying capacity” of
the marshes for these organisms and to quantify the marshes’ role as a
“nursery” for marine organisms.
Donald Kinsey was Director in the Institute
from 1978 to 1982. He established the utilization of the Main
House as a small conference center and introduced a coherent, institutional
level program to consider the unresolved questions associated with
the concept commonly known as “outwelling.”
Outwelling is the phenomenon whereby
the excess plant matter produced by the saltmarshes is assumed to
be transported by the tides to the nearshore zone, there contributing
to the overall food web. Thus the nearshore fisheries are assumed
to be supported partially by saltmarsh productivity.
Kinsey’s research used oxygen budget
techniques to address the question of the total carbon balance for
the inshore continental shelf. He carried out a detailed study
of the close inshore environment to estimate total photosynthetic and
metabolic turnover in that area.
The various nearshore projects established
that there is an important, large-scale contribution of organic matter
to the nearshore by outwelling from the marsh/estuarine system.
However, there is also extraordinary phytoplankton production.
The nearshore environment is characterized by organic input, large-scale
nutrient regeneration, and a food web made up of two distinctly different
sets of trophic interactions: (1) a phytoplankton-based web using nutrients
regenerated from estuarine material; (2) a heterotrophic web directly
utilizing the outwelled estuarine material (detritus) as a carbon source.
In 1984, Jim Alberts was named Director
of the Marine Institute. While continuing to encourage the resident
scientists to pursue their research interests, he has tried to bring
more participation from researchers not resident on Sapelo.
The Visiting Scientist Program, which had been initiated by Kinsey,
was expanded and a Postdoctoral position was established. Both
of these programs have brought several scientists to the Institute to
collaborate with the resident faculty. The programs have been effective
in not only attracting U.S. scientists, but also in bringing researchers
from Sweden, Denmark, Germany, Israel, Canada, Spain, Australia, Switzerland,
Studies conducted by Paul Kemp, a postdoctoral
fellow from Oregon State University, quantified the transfer of nitrogen
from the Spartina/aufwuchs community to the grazing snail Littorina
irrorata. Reinhard Bolliger (Switzerland), in cooperation with Kiene,
has been investigating the role of the iron cycle in sulfur biogeochemistry.
Christiane Krambeck (West Germany) and Newell have looked at the effectiveness
of bivalve filtration on cropping of bacterial populations. Larry
Albright (Canada) and the Sherrs have studied the effect of the presence
of suspended particles on the ingestion of bacteria by protozoa.
Carlos Pedr(s-Ali( (Spain) and Newell have measured the proportion of saltmarsh
bacterioplankton which is actually growing. Pete Peterson (University
of North Carolina) and Kneib have examined the extent to which marsh mussels
are protected by position of settlement from being eaten by mud crabs.
Bengt-Owe Jansson (Sweden) and Hopkinson investigated the benthic respiration
of the offshore living hard bottom communities and compared them to communities
in the Baltic Sea.
Zdenek Filip (West Germany), in collaboration
with Alberts, has studied the production of naturally occurring organic
matter by Spartina and compared this with other humic materials found
in nature. Humic matter is the largest single fraction of natural
organic matter and is extremely important in interacting with potentially
toxic heavy metals and organic compounds produced by man. The role
of natural organics brought from the uplands is now being pursued by John
Ertel and studies of the interactions of heavy metals with these compounds
has continued with work done by James Weber (University of New Hampshire)
and Thomas Tisue (Clemson University), all in conjunction with Alberts.
The Marine Institute continues to focus
on critical problems of marsh ecology and the transport and fate of
materials brought from the upland and marsh through the estuary and
into the nearshore. It attempts to address the difficult process-oriented
questions which define the mechanisms by which saltmarsh ecosystems
maintain themselves. In doing so, the Marine Institute fosters an
atmosphere of cooperative research, employing the expertise of the resident
faculty and numerous visiting scientists, and offers facilities to researchers
trying to understand the basic processes controlling the health of this