34
phic diatoms Rhizosolenia and Hemiaulus with the cyanobacterium Richelia] have
been compiled in Carpenter (1973).
Claude Zobell, often referred to as the father of marine microbiology, recounted
the early studies of diazotrophic marine bacteria such as Azotobacter (ZoBell 1946).
He also noted that BNF had been uncovered in some terrestrial cyanobacteria, predating the important role that cyanobacteria would be found to play in the oceans.
Systematic broad scale studies by marine chemists of the distribution of nutrients in
the sea began in the early part of the twentieth century (Cooper 1937; Harvey 1927),
and led to the question of which primary nutrient or nutrients were critical in limiting
oceanic primary productivity. The esteemed marine biologist Alfred Redfield wrote
a string of influential papers beginning in 1934 (Redfield 1934) considering the stoichiometry of inorganic N and P and factors limiting marine productivity (Redfield
et al. 1963; Redfield 1958). In one key observation Redfield (1934) first noted a
strong correspondence between the ratio of N to P in the biomass of marine plankton
and the pools of nitrate and phosphate in the deep ocean, now referred to as the
Redfield ratio of 106C:16 N:1P. He concluded that the concentrations and ratios of
these nutrients were controlled by organic matter produced in surface waters which
fell into the deep ocean and was regenerated (Falkowski 2000; Redfield 1958).
After consulting with his colleague, the famed Yale ecologist, GE Hutchinson
(1944) speculated that P rather than N was likely the most important limiting nutrient in the sea as N 2 fixation could make up any deficits, whereas the only source of
P was weathering of terrestrial minerals. Thus, for many years, N 2 fixation was
largely ignored by plankton ecologists and biological oceanographers, because it
was assumed to be unimportant or insignificant in regulating primary productivity.
This was largely based on the argument that the ultimate limiting nutrient was phosphorus and that N 2 fixation would simply compensate for any N deficit which arose
(Redfield 1958; Tyrrell 1999).
Microbiologists were simultaneously beginning to explore the N cycle in other
marine systems. Selman Waksman, a soil microbiologist, spent summers doing
research at the Marine Biological Laboratory in Wood Hole, MA and focused on the
N cycle in sediments, including N 2 fixation (Waksman et al. 1933). Waksman went
on to earn a Nobel Prize in 1952 for his discovery of the antibiotic streptomycin.
N 2 fixation was also on the minds of scientists considering abyssal ocean environments as well. Zobell and Morita (1959) speculated that deep sea bacteria might
be diazotrophic. Sisler and Zobell (1951) had earlier reported on the ability of some
sulfate respiring bacteria, key players in many marine sediments, to fix N 2 .
3.2 Process Oriented Studies: Water Column
N is now known to be the proximal primary limiting nutrient through large areas of
the surface ocean (Moore et al. 2013), although geochemists still argue that over
long geological time-scales (thousands of years), P is the ultimate limiting nutrient
3 History of Research on Marine N 2 Fixation
phic diatoms Rhizosolenia and Hemiaulus with the cyanobacterium Richelia] have
been compiled in Carpenter (1973).
Claude Zobell, often referred to as the father of marine microbiology, recounted
the early studies of diazotrophic marine bacteria such as Azotobacter (ZoBell 1946).
He also noted that BNF had been uncovered in some terrestrial cyanobacteria, predating the important role that cyanobacteria would be found to play in the oceans.
Systematic broad scale studies by marine chemists of the distribution of nutrients in
the sea began in the early part of the twentieth century (Cooper 1937; Harvey 1927),
and led to the question of which primary nutrient or nutrients were critical in limiting
oceanic primary productivity. The esteemed marine biologist Alfred Redfield wrote
a string of influential papers beginning in 1934 (Redfield 1934) considering the stoichiometry of inorganic N and P and factors limiting marine productivity (Redfield
et al. 1963; Redfield 1958). In one key observation Redfield (1934) first noted a
strong correspondence between the ratio of N to P in the biomass of marine plankton
and the pools of nitrate and phosphate in the deep ocean, now referred to as the
Redfield ratio of 106C:16 N:1P. He concluded that the concentrations and ratios of
these nutrients were controlled by organic matter produced in surface waters which
fell into the deep ocean and was regenerated (Falkowski 2000; Redfield 1958).
After consulting with his colleague, the famed Yale ecologist, GE Hutchinson
(1944) speculated that P rather than N was likely the most important limiting nutrient in the sea as N 2 fixation could make up any deficits, whereas the only source of
P was weathering of terrestrial minerals. Thus, for many years, N 2 fixation was
largely ignored by plankton ecologists and biological oceanographers, because it
was assumed to be unimportant or insignificant in regulating primary productivity.
This was largely based on the argument that the ultimate limiting nutrient was phosphorus and that N 2 fixation would simply compensate for any N deficit which arose
(Redfield 1958; Tyrrell 1999).
Microbiologists were simultaneously beginning to explore the N cycle in other
marine systems. Selman Waksman, a soil microbiologist, spent summers doing
research at the Marine Biological Laboratory in Wood Hole, MA and focused on the
N cycle in sediments, including N 2 fixation (Waksman et al. 1933). Waksman went
on to earn a Nobel Prize in 1952 for his discovery of the antibiotic streptomycin.
N 2 fixation was also on the minds of scientists considering abyssal ocean environments as well. Zobell and Morita (1959) speculated that deep sea bacteria might
be diazotrophic. Sisler and Zobell (1951) had earlier reported on the ability of some
sulfate respiring bacteria, key players in many marine sediments, to fix N 2 .
3.2 Process Oriented Studies: Water Column
N is now known to be the proximal primary limiting nutrient through large areas of
the surface ocean (Moore et al. 2013), although geochemists still argue that over
long geological time-scales (thousands of years), P is the ultimate limiting nutrient
3 History of Research on Marine N 2 Fixation