36
Capone and Carpenter (1982) summarized much of this new wave of studies and
concluded it was probably still a minor facet of the globally integrated oceanic
water column N cycle.
In the late 1990s new biogeochemical assessments analyzing robust global nutrient data sets noted strong deviations, both positive and negative from Redfield stoichiometry with respect to the regeneration of nitrate and phosphate in different
areas of the oceans. These studies highlighted the importance of the balance of
denitrification by N 2 fixation, and a possible large imbalance in the estimated N
budget (Codispoti 1995; Gruber and Sarmiento 1997; Michaels et al. 1996) which
strongly suggested that there were major gaps in knowledge about marine N 2 fixation. Subsequent decades of research, facilitated by molecular biology, satellite
remote sensing and tracer technologies shed new light on the diversity of N 2 -fixing
organisms, their biogeography and biogeochemical significance, and have radically
changed our view of the importance of oceanic N 2 fixation.
Efforts to mathematically represent important biogeochemical process in
Biological Oceanography goes back at least to Gordon Riley (Riley 1965; Riley
et al. 1949) who modeled primary production on a regional scale with the components of nutrients, phytoplankton and zooplankton commonly referred to as the
NPZ model (see Fasham (1993)). Another ocean biology modeling pioneer, John
Steele (Steele 1958) was interested in providing a context for fisheries production
from primary production in his modeling efforts. Richard Dugdale, who had earlier
provided the tools to initiate quantitative studies of N 2 fixation, also developed a
mathematical framework for analyzing nutrient limitation in phytoplankton based
on Michaelis-Menton kinetics which included N 2 fixation (Dugdale 1967). The first
global ocean biogeochemical model that we are aware of which explicitly represented N 2 fixation was Shaffer (1989).
3.3 Benthic Marine Environments
Research into N 2 fixation in benthic marine environments also saw a surge in the
late 1960s due to availability of the new technologies introduced into the field.
Significant, but lower globally integrated rates were noted in a variety of shallow
benthic environments where new research was also proceeding (Capone and
Carpenter 1982).
Several studies focused on cyanobacteria. WDP Stewart, one of the innovators of
the acetylene reduction technique (Stewart et al. 1967), provided some of the earliest quantitative evidence of the importance of heterocyst-forming cyanobacteria in
shallow benthic marine environments including a rocky shore and a dune-slack
(Stewart 1965, 1967).
Eugene and Howard Odum, seminal systems ecologists of their time (and brothers), undertook a classic study of the trophic structure of the coral reefs in the
Eniwetok lagoon in the Marshall Islands, one of the sites of the U.S. nuclear bomb
testing in the Pacific Ocean (Odum and Odum 1955). In trying to reconcile the very
3 History of Research on Marine N 2 Fixation
Capone and Carpenter (1982) summarized much of this new wave of studies and
concluded it was probably still a minor facet of the globally integrated oceanic
water column N cycle.
In the late 1990s new biogeochemical assessments analyzing robust global nutrient data sets noted strong deviations, both positive and negative from Redfield stoichiometry with respect to the regeneration of nitrate and phosphate in different
areas of the oceans. These studies highlighted the importance of the balance of
denitrification by N 2 fixation, and a possible large imbalance in the estimated N
budget (Codispoti 1995; Gruber and Sarmiento 1997; Michaels et al. 1996) which
strongly suggested that there were major gaps in knowledge about marine N 2 fixation. Subsequent decades of research, facilitated by molecular biology, satellite
remote sensing and tracer technologies shed new light on the diversity of N 2 -fixing
organisms, their biogeography and biogeochemical significance, and have radically
changed our view of the importance of oceanic N 2 fixation.
Efforts to mathematically represent important biogeochemical process in
Biological Oceanography goes back at least to Gordon Riley (Riley 1965; Riley
et al. 1949) who modeled primary production on a regional scale with the components of nutrients, phytoplankton and zooplankton commonly referred to as the
NPZ model (see Fasham (1993)). Another ocean biology modeling pioneer, John
Steele (Steele 1958) was interested in providing a context for fisheries production
from primary production in his modeling efforts. Richard Dugdale, who had earlier
provided the tools to initiate quantitative studies of N 2 fixation, also developed a
mathematical framework for analyzing nutrient limitation in phytoplankton based
on Michaelis-Menton kinetics which included N 2 fixation (Dugdale 1967). The first
global ocean biogeochemical model that we are aware of which explicitly represented N 2 fixation was Shaffer (1989).
3.3 Benthic Marine Environments
Research into N 2 fixation in benthic marine environments also saw a surge in the
late 1960s due to availability of the new technologies introduced into the field.
Significant, but lower globally integrated rates were noted in a variety of shallow
benthic environments where new research was also proceeding (Capone and
Carpenter 1982).
Several studies focused on cyanobacteria. WDP Stewart, one of the innovators of
the acetylene reduction technique (Stewart et al. 1967), provided some of the earliest quantitative evidence of the importance of heterocyst-forming cyanobacteria in
shallow benthic marine environments including a rocky shore and a dune-slack
(Stewart 1965, 1967).
Eugene and Howard Odum, seminal systems ecologists of their time (and brothers), undertook a classic study of the trophic structure of the coral reefs in the
Eniwetok lagoon in the Marshall Islands, one of the sites of the U.S. nuclear bomb
testing in the Pacific Ocean (Odum and Odum 1955). In trying to reconcile the very
3 History of Research on Marine N 2 Fixation