Trichodesmium , a Globally Significant Marine Cyanobacterium

Abstract

Planktonic marine cyanobacteria of the genus Trichodesmium occur throughout the oligotrophic tropical and subtropical oceans. Their unusual adaptations, from the molecular to the macroscopic level, contribute to their ecological success and biogeochemical importance. Trichodesmium fixes nitrogen gas (N 2 ) under fully aerobic conditions while photosynthetically evolving oxygen. Its temporal pattern of N 2 fixation results from an endogenous daily cycle that confines N 2 fixation to daylight hours. Trichodesmium colonies provide a unique pelagic habitat that supports a complex assemblage of consortial organisms. These colonies often represent a large fraction of the plant biomass in tropical, oligotrophic waters and contribute substantially to primary production. N 2 fixation by Trichodesmium is likely a major input to the marine and global nitrogen cycle.

Occurrence of brackish water phytoplankton species at a closed coral reef in Nansha Islands, South China Sea

“…This result is possibly related to the impact of currents in the SCS rather than nutrients level in this area (this issue is discussed later). Moreover, the dominance of filamentous cyanobacteria Trichodesmium in the reef flat waters agrees with previous studies of sub-and tropical oceanic environments (Ye and Yuan, 1982;Capone et al, 1997) and is primarily as a result of nitrogen-fixing capacity of the cyanobacteria in the oligotrophic marine systems (Mulholland and Capone, 2000).…”

Interactions between CCM and N2 fixation in Trichodesmium

“…N 2 fixation rates, obtained from acetylene reduction assays, have been shown to increase up to light intensities of about 300 lmol photons m -2 s -1 (Bell and Fu 2005;Breitbarth et al 2008). As cell densities of Trichodesmium are often highest at depths of 20-40 m (Capone et al 1997), prevailing light intensities may commonly limit the energy supply to nitrogenase in natural populations (SanudoWilhelmy et al 2001). …”

Spatial variation in N<sub>2</sub>-fixation rate and diazotroph activity in the Tropical Atlantic

“…Correspondence to: J. P. Montoya (montoya@gatech.edu) The best-known marine diazotrophs are colonial cyanobacteria of the genus Trichodesmium, which occurs broadly in subtropical and tropical waters throughout the world (Capone et al, 1997). Trichodesmium often forms dense surface blooms of large spatial extent and can clearly make a significant contribution to the local and global budget of oceanic nitrogen (Capone et al, 2005;Karl et al, 2002).…”

“…Trichodesmium often forms dense surface blooms of large spatial extent and can clearly make a significant contribution to the local and global budget of oceanic nitrogen (Capone et al, 2005;Karl et al, 2002). Because of its size and prominence at sea, Trichodesmium has received a great deal of attention in both field (Capone et al, 1997;Carpenter, 1992;Capone et al, 2005) and laboratory studies (Ohki et al, 1986;Chen et al, 1996;Mulholland and Capone, 1999;Mulholland et al, 2004). As a result, we now have a much better understanding of the environmental factors and physiological underpinnings of N 2 -fixation by Trichodesmium than we do for any other marine diazotroph.…”