Seasonality of picophytoplankton chlorophyll a and biomass in the central Cantabrian Sea, southern Bay of Biscay

Calvo‐Díaz, Alejandra; Morán, Xosé Anxelu G.; Suárez, Luis Ángel

doi:10.1016/j.jmarsys.2007.03.008

Cited by 54 publications

(59 citation statements)

References 33 publications

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“…1C illustrates that chl a values were largely independent from one month to the next, precluding the existence of significant temporal autocorrelation in our dataset. Monthly variations in temperature, nutrients and phytoplankton and bacterioplankton standing stocks (Table 1) were highly consistent with previous reports (Calvo-Díaz & Morán 2006, Calvo-Díaz et al 2008. Mean cellular carbon content of bacteria in the euphotic zone ranged between 14.6 and 18.7 fg C cell -1 (Table 1).…”

Section: Methodssupporting

confidence: 89%

Total and phytoplankton mediated bottom-up control of bacterioplankton change with temperature in NE Atlantic shelf waters

Morán¹,

Calvo‐Díaz²,

Ducklow³

2010

Aquat. Microb. Ecol.

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The regulation of heterotrophic bacterial growth by resource supply (bottom-up control) was temperature-dependent in our analysis of data obtained during 2006 in the euphotic layer of the southern Bay of Biscay (NE Atlantic) continental shelf. The dataset was split into 2 subgroups using 16°C as the boundary between warm and cool waters based on differences in associated physicochemical conditions, e.g. inorganic nutrient limitation at higher temperatures. The linear regressions between bacterial biomass (BB) and leucine incorporation rates (LIR) were significantly positive in both temperature regimes, thus indicating similar total bottom-up control, albeit with a slightly higher slope in warm waters (0.33 vs. 0.22). However, the relationship of LIR with phytoplankton biomass (chl a), which is an indicator of bottom-up control that is mediated by phytoplankton, was only significant in waters below 16°C. The analysis of bimonthly variations in the BB-LIR and LIR-chl a correlations indicated that the strength of total bottom-up control significantly increased while the role of phytoplankton in supplying DOM to bacteria diminished with mean temperatures over the 12 to 19°C range, suggesting a seasonal switch in the major source of substrates used by bacteria. We show that the abundance of cells with relatively high nucleic acid content (HNA), which are hypothesized to be the most active ones, was positively associated with bacterial production and specific growth rates in cool but not in warm conditions. These results suggest that HNA bacteria are good predictors of bulk activity and production in temperate ecosystems only when the community relies principally on phytoplankton substrates for growth and metabolism.

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Section: Methodssupporting

confidence: 89%

Total and phytoplankton mediated bottom-up control of bacterioplankton change with temperature in NE Atlantic shelf waters

Morán¹,

Calvo‐Díaz²,

Ducklow³

2010

Aquat. Microb. Ecol.

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“…Single-celled autotrophic picoplankton were not counted, but their biomass can be estimated roughly from the chl a content of the < 3 µm fraction at 5 m depth. Assuming a rather conservative C:chl a ratio of 40 (Calvo-Díaz et al 2008) and a similar contribution of the < 3 µm fraction in the integrated as in the 5 m sample (~10% of total chl a in spring, 54% in early summer and 45% in late summer), picoplankton contributed approximately 8% of total seston C in spring and 15% in summer. C from heterotrophic bacteria (data from Johansson et al 2004) accounted for an additional 9% (3.5 to 17%), with the lowest value in spring (3.5 to 5%), intermediate in early summer (6.5 to 11%) and highest in late summer (9.2 to 16%).…”

Section: Estimates Of Biomass In Seston At Landsort Deepmentioning

confidence: 92%

Seasonal changes in Baltic Sea seston stoichiometry: the influence of diazotrophic cyanobacteria

Walve¹,

Larsson²

2010

Mar. Ecol. Prog. Ser.

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We studied nutrient deficiency of Baltic Sea phytoplankton, as indicated by C:N:P ratios in filamentous N 2 -fixing (diazotrophic) cyanobacteria and size-fractions of seston. Samples were collected during an annual cycle in the NW Baltic proper (1998, Landsort Deep) and in 2 summers in the central Baltic proper (1997 and 1998, Gotland Basin). Generally, seston C:N:P ratios in the top 20 m were close to Redfield values. There was a transient increase in the C:N ratio at the end of the phytoplankton spring bloom (to ~9 mol:mol), concomitant with the depletion of dissolved inorganic N (DIN), but not dissolved inorganic phosphorus (DIP), indicating that phytoplankton became N-limited at the end of the spring bloom. In early summer (May-June), seston C:N:P ratios indicated weak N limitation of the community of small phytoplankton. From June through summer, seston size-fractions <10 µm accumulated mainly C and N, resulting in a September peak in seston C:P and N:P ratios (201 and 23 mol:mol, respectively) in the surface water. This change occurred in parallel with an increase in C:P and N:P ratios of diazotrophic filamentous cyanobacteria to levels indicative of severe P limitation of cyanobacterial growth. This suggests that the cyanobacterial P demand and new N from their N 2 fixation caused a weak P deficiency also in non-diazotrophs. However, the small increase in seston N:P, as well as a seston C:N above the Redfield ratio, indicate that N and P are nearly colimiting for non-diazotrophs at the culmination of the cyanobacterial bloom in late summer.

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“…The cell biovolume of the prokaryotes was estimated using the calibration obtained by Calvo-Díaz et al (2008) for oceanic samples, which relates relative side scatter (population SSC divided by bead SSC) to cell size. We used the same beads as in that study.…”

Section: Fc Countsmentioning

confidence: 99%

Global abundance of planktonic heterotrophic protists in the deep ocean

et al. 2014

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The dark ocean is one of the largest biomes on Earth, with critical roles in organic matter remineralization and global carbon sequestration. Despite its recognized importance, little is known about some key microbial players, such as the community of heterotrophic protists (HP), which are likely the main consumers of prokaryotic biomass. To investigate this microbial component at a global scale, we determined their abundance and biomass in deepwater column samples from the Malaspina 2010 circumnavigation using a combination of epifluorescence microscopy and flow cytometry. HP were ubiquitously found at all depths investigated down to 4000 m. HP abundances decreased with depth, from an average of 72 ± 19 cells ml À 1 in mesopelagic waters down to 11 ± 1 cells ml À 1 in bathypelagic waters, whereas their total biomass decreased from 280±46 to 50±14 pg C ml À 1 . The parameters that better explained the variance of HP abundance were depth and prokaryote abundance, and to lesser extent oxygen concentration. The generally good correlation with prokaryotic abundance suggested active grazing of HP on prokaryotes. On a finer scale, the prokaryote:HP abundance ratio varied at a regional scale, and sites with the highest ratios exhibited a larger contribution of fungi molecular signal. Our study is a step forward towards determining the relationship between HP and their environment, unveiling their importance as players in the dark ocean's microbial food web.

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Seasonality of picophytoplankton chlorophyll a and biomass in the central Cantabrian Sea, southern Bay of Biscay

Cited by 54 publications

References 33 publications

Total and phytoplankton mediated bottom-up control of bacterioplankton change with temperature in NE Atlantic shelf waters

Total and phytoplankton mediated bottom-up control of bacterioplankton change with temperature in NE Atlantic shelf waters

Seasonal changes in Baltic Sea seston stoichiometry: the influence of diazotrophic cyanobacteria

Global abundance of planktonic heterotrophic protists in the deep ocean

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