Heterotrophic Bacteria Respond Differently to Increasing Temperature and Dissolved Organic Carbon Sources in Two Tropical Coastal Systems

Lønborg, Christian; Baltar, Federico; Calleja, María Ll.; Morán, Xosé Anxelu G.

doi:10.1029/2022jg006890

Cited by 3 publications

(4 citation statements)

References 115 publications

(183 reference statements)

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“…Maximum bacterial contributions occurred in the DCM, where up to 40% of POC and 55% of PN at station P1, and 38% of POC and 50% of PN at station P2 were of bacterial origin. The enhanced bacterial contributions in the DCM suggest that labile substrates stimulate bacterial growth (Lønborg et al., 2022; Obernosterer et al., 2008). However, below the DCM to a depth of 500 m, the bacterial contribution decreased pronouncedly and then remained largely unchanged at greater depths.…”

Section: Resultsmentioning

confidence: 99%

“…However, under the nutrient limiting conditions above 200 m (Ma, Song, Li, Wang, Yuan, et al., 2021), most of the degraded organic matter is used for energy supply (i.e., respiration) rather than biomass growth (del Giorgio & Cole, 1998). Increasing temperatures can raise the respiration rates of bacteria (Lønborg et al., 2022; Rivkin & Legendre, 2001). Thus, high temperatures in the WPWP further promote bacterial POM degradation (Marsay et al., 2015).…”

Section: Resultsmentioning

confidence: 99%

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Rapid Cycling of Bacterial Particulate Organic Matter in the Upper Layer of the Western Pacific Warm Pool

Guo

Zhou

Achterberg

et al. 2023

Geophysical Research Letters

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The ocean is the largest carbon reservoir of the surface earth system, plays an important role in the global carbon cycle, and has absorbed about one-third of anthropogenic carbon dioxide (CO 2 ) emissions since the Industrial Revolution (Le Quéré et al., 2016). Sinking of particulate organic matter (POM) links CO 2 fixed through photosynthesis by phytoplankton in the surface ocean with carbon storage in the ocean interior. This pathway has been conceptualized as the biological carbon pump (BCP), and represents a key carbon sequestration mechanism (Llonghurst & Harrison, 1989;Turner, 2015). Bacteria play a crucial role in the efficiency of the BCP since most POM undergoes fast remineralization in the upper ocean and only a small fraction (∼10%) is exported to the mesopelagic zone (Buesseler & Boyd, 2009;Le Moigne et al., 2016). Compiled global budgets suggest that bacterial carbon demand in the dark ocean exceeds the influx of sinking POM (Burd et al., 2010). Although the supply of organic substrate is not well constrained, suspended POM is recognized as a potential carbon source for deep ocean metabolic activity (Baltar et al., 2010). Heterotrophic bacteria are not only consumers of organic matter but also contributors. Their metabolic activity utilizes a large fraction of the primary production and contributes non-living organic matter to the ocean in the form of bacterial detritus. Kaiser and Benner (2008) found that ∼25% of suspended particulate organic carbon (POC) is derived from bacteria. Attached bacteria are more likely to colonize suspended particles compared to sinking

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Rapid Cycling of Bacterial Particulate Organic Matter in the Upper Layer of the Western Pacific Warm Pool

Guo

Zhou

Achterberg

et al. 2023

Geophysical Research Letters

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“…Labile organic matter can rapidly produce microbial responses resulting in a cascade of biogeochemical processes in specific regions, thereby creating biological hot spots (McClain et al., 2003; Shen et al., 2016; Stocker et al., 2008). Incubation experiments and field investigations have shown that the supply of bioactive substrates stimulates increases in bacterial biomass and production (Buchan et al., 2014; Lønborg et al., 2022; Obernosterer et al., 2008). Likewise, in the present study, we found that regions with elevated bioavailable POM were associated with heterotrophic bacterial blooms (significant positive correlations were found between PAA‐C% and HBA; Figure S3 in Supporting Information ; spring: r = 0.40, p < 0.01; autumn: r = 0.61, p < 0.01).…”

Section: Discussionmentioning

confidence: 99%

“…Bacterial metabolism can convert labile organic matter to refractory organic matter, thus contributing to long‐term carbon sequestration (Jiao et al., 2010). The bacterial growth efficiency (BGE) varies from 0.1 to 63 in coastal systems, but there is evidence of elevated BGE in nutrient‐rich, highly productive waters (del Giorgio et al., 1997; Lønborg et al., 2022; Rivkin & Legendre, 2001). In the eutrophic CEAA, regions with high bacterial organic carbon contributions are associated with biological hot spots as indicated by the significant positive correlations between PAA‐C% and bacterial contribution (Figure S4 in Supporting Information ; spring: r = 0.70, p < 0.01; autumn: r = 0.55, p < 0.01), suggesting that hydrodynamically driven biological hot spots promote potential carbon sequestration (Zhu et al., 2014).…”

Section: Discussionmentioning

confidence: 99%

Influence of Hydrodynamics on the Composition and Reactivity of Particulate Organic Matter in a Large River Influenced Ocean Margin

Guo,

Zhou,

Achterberg

et al. 2024

JGR Oceans

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Marginal seas influenced by large rivers are characterized by complex hydrodynamic and organic matter cycling processes. However, the impacts of hydrodynamics on the composition and reactivity of particulate organic matter (POM) remain unclear. Here we conducted a comprehensive study on the bulk, molecular and biological properties of suspended POM in the Changjiang Estuary and adjacent area subjected to strong currents, eddies as well as typhoons during spring and autumn. D/L‐enantiomers of particulate amino acids (PAA) were analyzed to evaluate the bioreactivity of POM and quantify bacterial‐derived organic carbon. We found that POM bioavailability as indicated by carbon‐normalized yields of PAA (PAA‐C%) reflected the ecosystem productivity. Relatively high PAA‐C% values (20−35%) were observed in productive areas influenced by Changjiang River plume, cyclonic eddies and typhoons, likely related to the enhanced nutrient availability arising from hydrodynamic processes. In contrast, the oligotrophic Taiwan Warm Current‐influenced regions featured relatively low POM bioavailability (PAA‐C% < 10%) despite typhoons facilitating water mixing. The PAA‐C% values showed a significant positive correlation with extracellular enzyme activity, indicating that bioavailable POM can rapidly stimulate heterotrophic transformation. Hot spots of elevated bioavailable POM showed high contributions of bacterial organic carbon. A large portion (∼2/3) of bacterial organic carbon was present in the form of bacterial detritus, suggesting that patches of these biological hot spots represent important sites of carbon sequestration. Together, our findings indicate that fresh POM production is largely controlled by nutrient supply driven by hydrodynamic processes, with important implications for carbon sequestration in the dynamic ocean margins.

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Differential impacts of temperature increase on prokaryotes across temperature regimes in subtropical coastal waters: insights from field experiments

Gu,

Ma,

Chen

et al. 2024

Limnology & Oceanography

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Prokaryotic communities play a dominant role in driving biogeochemical cycling in marine ecosystems. How short‐term temperature increase impacts prokaryotes in subtropical coastal waters is still largely unknown. Here, 14 field experiments were conducted to investigate the response of prokaryotes in subtropical coastal waters to temperature increases of 3°C and 6°C, encompassing a range of ambient temperatures from 17°C to 31°C. We found that responses of prokaryotic growth, grazing pressure, community, and transcriptomes to increased temperatures were largely affected by ambient temperatures. Increased temperatures enhanced the growth rate and grazing pressure of heterotrophic prokaryotes when ambient temperatures were below 26–28°C. The increased temperatures had greater negative effects on the grazing rate compared to the growth rate; therefore, the abundance of heterotrophic prokaryotes generally increased after temperature increase across all temperature regimes. Metatranscriptomics analysis showed that at an ambient temperature of 30°C, genes involved in the adenosine triphosphate synthase were significantly downregulated by the increased temperature. This could be a major factor contributing to the decreased prokaryotic growth rate. In comparison, autotrophic prokaryotes (Synechococcus) exhibited better performance in response to elevated temperatures, thriving up to 35°C, beyond which their growth rate experienced a dramatic decline. When exposing to extremely high temperatures, genes involved in photosynthesis significantly decreased. These findings highlight the differential ecological impacts of temperature increase on prokaryotic communities, varying across different ambient temperatures and taxa in subtropical coastal waters.

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Heterotrophic Bacteria Respond Differently to Increasing Temperature and Dissolved Organic Carbon Sources in Two Tropical Coastal Systems

Cited by 3 publications

References 115 publications

Rapid Cycling of Bacterial Particulate Organic Matter in the Upper Layer of the Western Pacific Warm Pool

Rapid Cycling of Bacterial Particulate Organic Matter in the Upper Layer of the Western Pacific Warm Pool

Influence of Hydrodynamics on the Composition and Reactivity of Particulate Organic Matter in a Large River Influenced Ocean Margin

Differential impacts of temperature increase on prokaryotes across temperature regimes in subtropical coastal waters: insights from field experiments

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