Projected expansion of <i>Trichodesmium</i>’s geographical distribution and increase in growth potential in response to climate change

Boatman, Tobias G.; Upton, Graham; Lawson, Tracy; Geider, Richard J.

doi:10.1111/gcb.15324

Cited by 6 publications

(9 citation statements)

References 82 publications

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Section: Responses To Warmingsupporting

confidence: 90%

“…Trichodesmium may increase by up to 173% by 2100 (Boatman et al, 2020). The study by Boatman et al (2020) also indicated that the thermal niche of Trichodesmium will likely expand at high latitudes and reduce in equatorial regions, agreeing with the findings of this study. It is worth noting however, that under lower emissions scenarios, the associated reduction in warming would reduce the extent of thermal stress for both diazotrophs by 12%-17% compared to the high emissions RCP8.5 scenario (Table 2; Figure S3).…”

Section: Responses To Warmingsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

“…Increasing sea surface temperature (SST) plays a primary role in controlling the thermal niche of diazotrophs. In the low latitudes, warming may surpass their thermal maximum leading to exclusion, whilst increasing temperatures below their thermal maximum allows poleward expansion (Boatman et al, 2020 ; Breitbarth et al, 2007 ; Fu et al, 2014 ). Changing nutrient supply due to stratification can either open a competitive niche for diazotrophy if the supply of N declines such that it limits non‐diazotrophs (Weber & Deutsch, 2010 ), or it can restrict rates of N 2 fixation if the supply of phosphorus (P) or iron (Fe) declines (Hutchins & Capone, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

“…However, current ESMs have an incomplete representation of N 2 fixation as focus is primarily upon the impacts of temperature on the niche of marine diazotrophs (Wrightson & Tagliabue, 2020 ). As temperature has the potential to modulate not only the extent of the thermal niche of diazotrophs but also their physiology via changing EUEs, diazotroph thermal fitness dynamics need to be incorporated into ESMs to assess the integrated climate change response (Boatman et al, 2020 ; Jiang et al, 2018 ; Yang et al, 2021 ). Such models should account for the temperature impacts on both the growth and niche of diazotrophs, as well as incorporating the effects of warming on diazotroph physiology via EUEs.…”

Section: Introductionmentioning

confidence: 99%

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Integrating the impact of global change on the niche and physiology of marine nitrogen‐fixing cyanobacteria

Yang

Mahaffey

Hutchins

et al. 2022

Global Change Biology

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Marine nitrogen fixation is a major source of new nitrogen to the ocean, which interacts with climate driven changes to physical nutrient supply to regulate the response of ocean primary production in the oligotrophic tropical ocean. Warming and changes in nutrient supply may alter the ecological niche of nitrogen-fixing organisms, or 'diazotrophs', however, impacts of warming on diazotroph physiology may also be important. Lab-based studies reveal that warming increases the nitrogen fixation-specific elemental use efficiency (EUE) of two prevalent marine diazotrophs, Crocosphaera and Trichodesmium, thus reducing their requirements for the limiting nutrients iron and phosphorus. Here, we coupled a new diazotroph model based upon observed diazotroph energetics of growth and resource limitation to a state-of-theart global model of phytoplankton physiology and ocean biogeochemistry. Our model is able to address the integrated response of nitrogen fixation by Trichodesmium and Crocosphaera to warming under the IPCC high emission RCP8.5 scenario for the first time. Our results project a global decline in nitrogen fixation over the coming century.However, the regional response of nitrogen fixation to climate change is modulated by the diazotroph-specific thermal performance curves and EUE, particularly in the Pacific Ocean, which shapes global trends. Spatially, the response of both diazotrophs is similar with expansion towards higher latitudes and reduced rates of nitrogen fixation in the lower latitudes. Overall, 95%-97% of the nitrogen fixation climate signal can be attributed to the combined effect of temperature on the niche and physiology of marine diazotrophs, with decreases being associated with a reduced niche and increases resulting due to a combination of expanding niche and temperature driven changes to EUE. Climate change impacts on both the niche and physiology of marine diazotrophs interact to shape patterns of marine nitrogen fixation, which will have important implications for ocean productivity in the future.

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Section: Responses To Warmingsupporting

confidence: 90%

Section: Responses To Warmingsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Integrating the impact of global change on the niche and physiology of marine nitrogen‐fixing cyanobacteria

Yang

Mahaffey

Hutchins

et al. 2022

Global Change Biology

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Better together? Lessons on sociality from Trichodesmium

Eichner

Inomura

Karlusich

et al. 2023

Trends in Microbiology

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Sinking Trichodesmium fixes nitrogen in the dark ocean

et al. 2022

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The photosynthetic cyanobacterium Trichodesmium is widely distributed in the surface low latitude ocean where it contributes significantly to N 2 fixation and primary productivity. Previous studies found nifH genes and intact Trichodesmium colonies in the sunlight-deprived meso-and bathypelagic layers of the ocean (200-4 000 m depth). Yet, the ability of Trichodesmium to fix N 2 in the dark ocean has not been explored. We performed 15 N 2 incubations in sediment traps at 170, 270 and 1 000 m at two locations in the South Pacific. Sinking Trichodesmium colonies fixed N 2 at similar rates than previously observed in the surface ocean (36-214 fmol N cell -1 d -1 ). This activity accounted for 40 ± 28 % of the bulk N 2 fixation rates measured in the traps, indicating that other diazotrophs were also active in the mesopelagic zone. Accordingly, cDNA nifH amplicon sequencing revealed that while Trichodesmium accounted for most of the expressed nifH genes in the traps, other diazotrophs such as Chlorobium and Deltaproteobacteria were also active. Laboratory experiments simulating mesopelagic conditions confirmed that increasing hydrostatic pressure and decreasing temperature reduced but did not completely inhibit N 2 fixation in Trichodesmium. Finally, using a cell metabolism model we predict that Trichodesmium uses photosynthesis-derived stored carbon to sustain N 2 fixation while sinking into the mesopelagic. We conclude that sinking Trichodesmium provides ammonium, dissolved organic matter and biomass to mesopelagic prokaryotes.

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Projected expansion of Trichodesmium’s geographical distribution and increase in growth potential in response to climate change

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 6 publications

References 82 publications

Integrating the impact of global change on the niche and physiology of marine nitrogen‐fixing cyanobacteria

Integrating the impact of global change on the niche and physiology of marine nitrogen‐fixing cyanobacteria

Better together? Lessons on sociality from Trichodesmium

Sinking Trichodesmium fixes nitrogen in the dark ocean

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