117
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
J. P. Zehr, D. G. Capone, Marine Nitrogen Fixation,
https://doi.org/10.1007/978-3-030-67746-6_7
Chapter 7
Biogeography of N 2 Fixation in the Surface
Ocean
7.1 Factors Controlling the Distribution of N 2 Fixation
Biogeography
N 2 fixation and N 2 -fixing microorganisms are not distributed uniformly throughout
the world’s oceans. The oceans are dynamic, circulating, and stratified. The absorption by these waters of energy from sunlight coupled with wind and the Earth’s
rotation (the Coriolis effect on water mass movement) drive the surface patterns of
temperature, salinity and nutrients. The surface oceans are comprised of multiple
biomes from cool high latitude to warm equatorial waters (Longhurst 2007). They
also range in nutrient concentrations and inputs from runoff, upwelling and atmospheric deposition. As for global patterns of primary productivity, light and temperature, dissolved N, P and Fe availability (both concentration and chemical form)
are believed to be the major factors controlling N 2 fixation rates and the distribution
of specific diazotrophs (Dutkiewicz et al. 2005, 2012; Landolfi et al. 2015; Sohm
et al. 2011c; Weber and Deutsch 2014) (see also Chaps. 4 and 6).
For many years, it was generally assumed that diazotrophy only occurred in
regions with low fixed N, relatively high P and/or high Fe availability and warm
temperatures. Early observations suggested control by temperature as substantial
rates of N 2 fixation was largely associated with warm tropical or subtropical waters
above 20 °C, where Trichodesmium and Richelia were often found (Breitbarth et al.
2007; Capone et al. 1997). Crocosphaera (Waterbury and Rippka 1989) and
UCYN-A were also first found in tropical waters (Zehr et al. 2001). However, estuarine diazotrophic species are present at lower temperatures in the Baltic Sea and
elsewhere (Farnelid et al. 2009; Niemi 1979; Ploug et al. 2010; Walve and Larsson
2010; Wasmund et al. 2001) and the UCYN-A symbiosis occurs over a much wider
geographic range, including more nutrient-enriched coastal (Mulholland et al. 2019;
Needham et al. 2018) and cooler high latitude waters (Bentzon-Tilia et al. 2015;
Harding et al. 2018; Shiozaki et al. 2018a).
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2021
J. P. Zehr, D. G. Capone, Marine Nitrogen Fixation,
https://doi.org/10.1007/978-3-030-67746-6_7
Chapter 7
Biogeography of N 2 Fixation in the Surface
Ocean
7.1 Factors Controlling the Distribution of N 2 Fixation
Biogeography
N 2 fixation and N 2 -fixing microorganisms are not distributed uniformly throughout
the world’s oceans. The oceans are dynamic, circulating, and stratified. The absorption by these waters of energy from sunlight coupled with wind and the Earth’s
rotation (the Coriolis effect on water mass movement) drive the surface patterns of
temperature, salinity and nutrients. The surface oceans are comprised of multiple
biomes from cool high latitude to warm equatorial waters (Longhurst 2007). They
also range in nutrient concentrations and inputs from runoff, upwelling and atmospheric deposition. As for global patterns of primary productivity, light and temperature, dissolved N, P and Fe availability (both concentration and chemical form)
are believed to be the major factors controlling N 2 fixation rates and the distribution
of specific diazotrophs (Dutkiewicz et al. 2005, 2012; Landolfi et al. 2015; Sohm
et al. 2011c; Weber and Deutsch 2014) (see also Chaps. 4 and 6).
For many years, it was generally assumed that diazotrophy only occurred in
regions with low fixed N, relatively high P and/or high Fe availability and warm
temperatures. Early observations suggested control by temperature as substantial
rates of N 2 fixation was largely associated with warm tropical or subtropical waters
above 20 °C, where Trichodesmium and Richelia were often found (Breitbarth et al.
2007; Capone et al. 1997). Crocosphaera (Waterbury and Rippka 1989) and
UCYN-A were also first found in tropical waters (Zehr et al. 2001). However, estuarine diazotrophic species are present at lower temperatures in the Baltic Sea and
elsewhere (Farnelid et al. 2009; Niemi 1979; Ploug et al. 2010; Walve and Larsson
2010; Wasmund et al. 2001) and the UCYN-A symbiosis occurs over a much wider
geographic range, including more nutrient-enriched coastal (Mulholland et al. 2019;
Needham et al. 2018) and cooler high latitude waters (Bentzon-Tilia et al. 2015;
Harding et al. 2018; Shiozaki et al. 2018a).