scholarly journals Influence of cyclonic and anti-cyclonic eddies on plankton biomass, activity and diversity in the southeastern Mediterranean Sea

2022 ◽  
Author(s):  
Natalia Belkin ◽  
Tamar Guy-Haim ◽  
Maxim Rubin-Blum ◽  
Ayah Lazar ◽  
Guy Sisma-Ventura ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Doubling Time ◽  
Heterotrophic Bacteria ◽  
Specific Activity ◽  
Late Summer ◽  
Zooplankton Biomass ◽  
Planktonic Food ◽  
C Cell ◽  
Plankton Biomass ◽  
Biomass Activity

Abstract. Planktonic food-webs were studied contemporaneously in a mesoscale cyclonic (upwelling, ~13 months old) and an anti-cyclonic (down-welling, ~2 months old) eddies, as well as in an uninfluenced-background situation in the oligotrophic southeastern Mediterranean Sea (SEMS) during late summer 2018. We show that integrated nutrients concentrations were higher at the cyclone compared to the anti-cyclone or the background stations by 2–13 fold. Concurrently, Synechococcus and Prochlorococcus were the dominant community component abundance-wise in the oligotrophic anti-cyclone (~300 × 1010 cells m−2). In the cyclone, pico- and nanoeukaryotes such as dinoflagellates, Prymnesiophyceae and Ochrophyta contributed substantially to the total phytoplankton abundnce (~14 × 1010 cells m−2) which was ~65 % lower in the anti-cyclone/background stations (~5 × 1010 cells m−2). Primary production was highest in the cyclonic eddy (191 mg C m−2 d−1) and was 2–5 fold lower outside the eddy area. The calculated doubling time of phytoplankton was ~3 days in the cyclone and ~5–10 days at the anti-cyclone/background stations, further reflecting the nutritional differences between these environments. Heterotrophic prokaryotic cell-specific activity was highest in the cyclone (~10 fg C cell−1 d−1), while the least productive cells were found in the anti-cyclone (4 fg C cell−1 d−1). The calculated doubling time of heterotrophic bacteria were 1.4 days in the cyclone and 2.5–3.5 days at the anti-cyclone/background stations. Total zooplankton biomass in the upper 300 m was tenfold higher in the cyclone compared with the anti-cyclone or background stations (1337 vs. 112–133 mg C m−2, respectively). Copepod diversity was much higher in the cyclone (44 species), compared to the anti-cyclone (6 small-size species). Our results highlight that cyclonic and anti-cyclonic eddies show significantly different community compositions and food-web dynamics in oligotrophic environments, with cyclones representing productive oases in the marine desert of the SEMS.

scholarly journals Response of heterotrophic and autotrophic microbial plankton to inorganic and organic inputs along a latitudinal transect in the Atlantic Ocean

2010 ◽  
Vol 7 (5) ◽  
pp. 1701-1713 ◽  
Author(s):  
S. Martínez-García ◽  
E. Fernández ◽  
A. Calvo-Díaz ◽  
E. Marañón ◽  
X. A. G. Morán ◽  
...  
Keyword(s):  
Organic Matter ◽  
Atlantic Ocean ◽  
Bacterial Growth ◽  
Heterotrophic Bacteria ◽  
Growth Efficiency ◽  
Bacterial Growth Efficiency ◽  
Organic Nutrient ◽  
Plankton Biomass ◽  
Latitudinal Transect ◽  
Microbial Plankton

Abstract. The effects of inorganic and/or organic nutrient inputs on phytoplankton and heterotrophic bacteria have never been concurrently assessed in open ocean oligotrophic communities over a wide spatial gradient. We studied the effects of potentially limiting inorganic (nitrate, ammonium, phosphate, silica) and organic nutrient (glucose, aminoacids) inputs added separately as well as jointly, on microbial plankton biomass, community structure and metabolism in five microcosm experiments conducted along a latitudinal transect in the Atlantic Ocean (from 26° N to 29° S). Primary production rates increased up to 1.8-fold. Bacterial respiration and microbial community respiration increased up to 14.3 and 12.7-fold respectively. Bacterial production and bacterial growth efficiency increased up to 58.8-fold and 2.5-fold respectively. The largest increases were measured after mixed inorganic-organic nutrients additions. Changes in microbial plankton biomass were small as compared with those in metabolic rates. A north to south increase in the response of heterotrophic bacteria was observed, which could be related to a latitudinal gradient in phosphorus availability. Our results suggest that organic matter inputs will result in a predominantly heterotrophic versus autotrophic response and in increases in bacterial growth efficiency, particularly in the southern hemisphere. Subtle differences in the initial environmental and biological conditions are likely to result in differential microbial responses to inorganic and organic matter inputs.

An Inverse Model Analysis of Planktonic Food Webs in Experimental Lakes

1994 ◽  
Vol 51 (9) ◽  
pp. 2034-2044 ◽  
Author(s):  
Alain F. Vézina ◽  
Michael L. Pace
Keyword(s):  
Food Web ◽  
Heterotrophic Bacteria ◽  
Grazing Pressure ◽  
Inverse Methods ◽  
Trophic Levels ◽  
Microbial Food Web ◽  
Food Web Structure ◽  
Planktonic Food ◽  
Size Groups ◽  
The Impact

We used inverse methods to reconstruct carbon flows in experimental lakes where the fish community had been purposely altered. These analyses were applied to three years of data from a reference lake and two experimental lakes located in Gogebic County, Michigan. We reconstructed seasonally averaged flows among two size groups of phytoplankton, heterotrophic bacteria, microzooplankton, cladocerans, and copepods. The inverse analysis produced significantly different flow networks for the different lakes that agreed qualitatively with known chemical and biological differences between lakes and with other analyses of the impact of fish manipulations on food web structure and dynamics. The results pointed to alterations in grazing pressure on the phytoplankton that parallel changes in the size and abundance of cladocerans and copepods among lakes. Estimated flows through the microbial food web indicated low bacterial production efficiencies and small carbon transfers from the microbial food web to the larger zooplankton. This study demonstrates the use of inverse methods to identify and compare flow patterns across ecosystems and suggests that microbial flows are relatively insensitive to changes at the upper trophic levels.

scholarly journals Short scale variations in nutrients, ectoenzymatic activities and bottom-up effects on bacterial production and community structure during late summer-autumn transition in the open NW Mediterranean Sea

2009 ◽  
Vol 6 (1) ◽  
pp. 687-727 ◽  
Author(s):  
F. Van Wambeke ◽  
J-F. Ghiglione ◽  
J. Nedoma ◽  
G. Mével ◽  
P. Raimbault
Keyword(s):  
Community Structure ◽  
Bacterial Community ◽  
Mediterranean Sea ◽  
Mixed Layer ◽  
Bacterial Production ◽  
Bacterial Community Structure ◽  
Late Summer ◽  
Bottom Up ◽  
Nw Mediterranean ◽  
Nw Mediterranean Sea

Abstract. We examined the vertical and temporal dynamics of nutrients, ectoenzymatic activities under late summer-fall transition period (September–October 2004) in NW Mediterranean Sea in relation to temporal change in factors limiting bacterial production. The depth of the mixed layer (12.8±5.3 m) was extremely stable until the onset of the destratification period after 11 October, creating a zone where diffusion of nutrient from the much deeper phosphacline (69±12 m) and nitracline (50±8 m) was probably strongly limited. However during the second half of the cruise, a shallowing of nutriclines occured, particularly marked for nitracline. Hence, the nitrate to phosphate ratio within the mixed layer, although submitted to a high short term variability, shifted the last week of the cruise from 1.1±1.2 to 4.6±3.8, and nitrate increased by a factor 2 (0.092±0.049 μM). A corresponding switch from more than one limitation (PN) to P-only limitation of bacterial production was observed during the month as detected by enrichment bioassays. Differences in the identity of the limiting nutrient in surface (5 m: N and P at the beginning, strictly P at the end of the study) versus 80 m (labile carbon) influence greatly bacterial community structure shift between these two layers. The two communities (5 and 80 m) reacted rapidly (24 h) to changes in nutrient concentrations by drastic modification of total and active population assemblages resulting in changes in activity. For bacterial production values less than 10 ng C l−1h−1 (associated to deeper layers), aminopeptidase and lipase exhibited higher activity relative to production whereas phosphatase varied in the same proportions than BP on the range of activities tested. Our results illustrate the effect of bottom-up control on bacterial community structure and activities in the epipelagic NW Mediterranean Sea.

scholarly journals Spatial distribution of picoseston in the Saratov reservoir in summer

2021 ◽  
pp. 176-190
Author(s):  
E. S. Krasnova ◽  
M. V. Umanskaya
Keyword(s):  
Spatial Distribution ◽  
Food Webs ◽  
Significant Contribution ◽  
Heterotrophic Bacteria ◽  
Total Biomass ◽  
Total Abundance ◽  
Saratov Reservoir ◽  
Autotrophic Picoplankton ◽  
Upper Volga ◽  
Planktonic Food

The structure and spatial distribution of picoseston in the Saratov reservoir in July 2011 and August 2014 are described. On average, the total abundance of cells and particles forming picoseston was 1.87±0.73×106 cells (part.)/mL; and the total biomass of picoseston was 43.8±19.4 µg C/L. During the study period, solitary heterotrophic bacteria and phototrophic picocyanobacteria prevailed in the picoseston of the Saratov reservoir, amounting to 77–100% of its total abundance and biomass. The proportion of picodetrital particles was extremely small (on average, 4.1% of the total biomass of picoseston). The high heterogeneity of picoceston distribution (Cv is 130% and 110% for abundance and biomass, respectively) was found in the Saratov reservoir during the study period. On average, the abundance and biomass of heterotrophic bacterioplaknton and picodetritus at stations of the tributary estuaries were slightly higher than in the riverbed. At the same time, the abundance of picocyanobacteria was higher, and the biomass was lower at the estuarine stations compared to the riverbed ones. The total number of bacterioplankton and autotrophic picoplankton in the Saratov reservoir in 2011 and 2014 corresponded to the mesotrophic level of productivity. Picodetrital particles, in contrast to the Upper Volga and Kama reservoirs, make no significant contribution to the planktonic food webs of the Saratov reservoir, at least during the study period.

scholarly journals Dynamics of various viral groups infecting autotrophic plankton in Lake Geneva

2012 ◽  
Vol 3 (2) ◽  
pp. 171 ◽  
Author(s):  
Ammini Parvathi ◽  
Xu Zhong ◽  
Stéphan Jacquet
Keyword(s):  
Carbon Fixation ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Heterotrophic Bacteria ◽  
Significant Proportion ◽  
Late Summer ◽  
Lake Geneva ◽  
Tight Coupling ◽  
Virus Like Particles ◽  
Signature Genes ◽  
Gradient Gel Electrophoresis

Viral community structure and dynamics were investigated for the first time in surface waters (0–20 m) of Lake Geneva over a 5-month period between July and November 2011. Abundances of autotrophic picoplankton, heterotrophic bacteria and virus-like particles determined using flow cytometry revealed their predominance during the summer months followed by a slight decrease in fall. Two groups of viruses could be discriminated, referred to as virus-like particles (VLP) group 1 and 2. The abundance of VLP1 correlated significantly with the bacterial abundance, while that of VLP2 correlated with both chlorophyll a and picocyanobacterial abundance suggesting a tight coupling between these viral groups and bacteria or phytoplankton. The abundance of cyanomyoviruses and cyanopodoviruses varied between 7.3 × 102 ml−1 (July) to 1.2 × 104 ml−1 (November) and 5.8 × 103 ml−1 (July) to 2.2 × 104 ml−1 (September), respectively. The abundance of the picocyanobacterial hosts was in concurrence with that of the cyanophages, being higher in late summer. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) of viral signature genes such as g20, g23, mcp, polB, psbA and psbD revealed a relatively high richness within these genes with their diversity increasing towards the summer months. The diversity of psbD was found to be particularly high and correlated with picocyanobacterial abundance suggesting that cyanophages may be directly responsible for a significant proportion of carbon fixation in Lake Geneva.

scholarly journals UNICELLULAR PLANKTON TRANSFORMATION IN THE RIVER-BAY-RESERVOIR SYSTEM IN THE INITIAL PHASE OF CYANOBACTERIAL BLOOM

2021 ◽  
Vol 23 (5) ◽  
pp. 144-151
Author(s):  
M.V. Umanskaya ◽  
◽  
S.V. Bykova ◽  
M.Yu. Gorbunov ◽  
E.S. Krasnova ◽  
...  
Keyword(s):  
Structural Transformation ◽  
Initial Phase ◽  
Heterotrophic Bacteria ◽  
Initial Period ◽  
Cyanobacterial Bloom ◽  
Kuibyshev Reservoir ◽  
Adjacent Section ◽  
Reservoir System ◽  
Plankton Biomass ◽  
Quantitative Characteristics

The structure and spatial distributionof unicellular plankton of the river Usa, Usinsky Bay and the adjacent section of the Kuibyshev reservoir in the initial period of cyanobacterial bloom is discussed. The greatest development of plankton was recorded in the central part of Usinsky Bay. In the river part, the basis of the total plankton biomass was formed by heterotrophic bacteria and diatoms, and in the bay and reservoir –by cyanobacteria, mainly of the genera Aphanizomenon and Anabaena. Among eukaryotes in Usinskiy Bay, chlorophytesand diatoms prevailed, and in the reservoir - diatoms and ciliates. Another feature of plankton in the bay and reservoir was the increased proportion of heterotrophic bacteria and ciliates associated with cyanobacteria. The analysis of the structural transformation of communities made it possible to distinguish two main clusters of communities, "lotic" and "letic", which differ in their structure and quantitative characteristics.

scholarly journals Spatio-temporal distribution of the dominant Diatom and Dinoflagellate species in the Bay of Tunis (SW Mediterranean Sea)

2005 ◽  
Vol 6 (1) ◽  
pp. 17 ◽  
Author(s):  
O. DALY YAHIA-KEFI ◽  
S. SOUISSI ◽  
F. GOMEZ ◽  
M.N. DALY YAHIA
Keyword(s):  
Mediterranean Sea ◽  
Chlorophyll Concentration ◽  
Temporal Distribution ◽  
Late Summer ◽  
Clear Correlation ◽  
Red Tides ◽  
Nutrient Inputs ◽  
Wide Range ◽  
Spatio Temporal ◽  
Diatom Blooms

Microphytoplankton composition and its relationships with hydrology and nutrient distributions were investigated over 24 months (December 1993 - November 1995) in the Bay of Tunis ( SW Mediterranean Sea). A new index, the ‘Specific Preference Index’ (SPI) obtained by computing the median value of each parameter weighed by the numerical value of each species density was developed. Using this index, the relationships between each species and temperature, salinity and major nutrients were analysed. The distribution of chlorophyll a did not show a clear correlation with microplankton abundance suggesting that other factors contribute to chlorophyll concentration, such as smaller phytoplankton size fractions or detritus. The winter-spring diatom blooms did not show a regular pattern during both years. High nutrient inputs in late summer, associated with mild meteorological conditions, contributed to the development of a large diatom bloom in autumn 1995 where significant silicate depletion was witnessed. Generally, diatoms were more stenotherm than dinoflagellates in the Bay, whereas dinoflagellates were more stenohaline than diatoms. The statistical analyses showed that the two species, Bellerochea horologicalis , and Lithodesmioides polymorpha, var., tunisiense, appeared in a wide range of environmental conditions. An excess of phosphateversus nitrate appeared to be associated with red tides of, Gymnodinium spp, whereas Peridinium quinquecorne, showed the opposite. Phosphate concentrations appear to be crucial in this coastal environment, where diatom blooms are often limited by low silicate availability.

Equilibrium Models for Seasonal Dynamics of Plankton Biomass in Four Oligotrophy Lakes

1987 ◽  
Vol 44 (5) ◽  
pp. 1002-1017 ◽  
Author(s):  
Carl J. Walters ◽  
Edith Krause ◽  
William E. Neill ◽  
Thomas G. Northcote
Keyword(s):  
Phytoplankton Biomass ◽  
Zooplankton Biomass ◽  
Seasonal Cycles ◽  
Zooplankton Grazing ◽  
Metabolic Rates ◽  
Phytoplankton Productivity ◽  
Plankton Biomass ◽  
Recovery Times ◽  
Biomass Dynamics ◽  
Coastal British Columbia

Plankton biomass dynamics were monitored over an 11-yr period in four coastal British Columbia lakes while they were disturbed by salmonid introductions, fertilization, and zooplankton harvesting. Except for dramatic zooplankton responses to fertilization, the lakes had relatively simple and stable seasonal biomass patterns, with midsummer zooplankton peaks and no clear seasonal cycles in biomass of unicellular phytoplankton. Simple models predict that equilibrium biomasses should follow the observed pattern, provided zooplankton grazing and metabolic rates are temperature independent; experimental measurements of these rates did not show clear temperature dependence. Enclosure studies showed that phytoplankton biomass can return quickly (48 – 72 h) to equilibrium after disturbance, but zooplankton biomass responds more slowly (2- to 3-wk recovery times), yet fast enough to track a seasonally varying equilibrium. We conclude that the biomass equilibrium of unicellular phytoplankton is set by grazing and metabolic rates of zooplankton, while the zooplankton biomass equilibrium is set by phytoplankton productivity.

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