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The Temporal Dynamics of Coastal Phytoplankton and Bacterioplankton in the Eastern Mediterranean Sea.

Raveh O, David N, Rilov G, Rahav E - PLoS ONE (2015)

Bottom Line: Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates.Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients.These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.

ABSTRACT
This study considers variability in phytoplankton and heterotrophic bacterial abundances and production rates, in one of the most oligotrophic marine regions in the world-the Levantine Basin. The temporal dynamics of these planktonic groups were studied in the coastal waters of the southeastern Mediterranean Sea approximately every two weeks for a total of two years. Heterotrophic bacteria were abundant mostly during late summer and midwinter, and were positively correlated with bacterial production and with N2 fixation. Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates. Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients. Furthermore, a comparison of our results with results from the open Levantine Basin demonstrates that autotrophic and heterotrophic production, as well as N2 fixation rates, are considerably higher in the coastal habitat than in the open sea, while nutrient levels or cell abundance are not different. These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.

No MeSH data available.


The temporal dynamics of N2 fixation in the coastal eastern Mediterranean Sea.Data was collected from April 2013 to April 2015, following 24 h incubations under ambient light and temperature.
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pone.0140690.g004: The temporal dynamics of N2 fixation in the coastal eastern Mediterranean Sea.Data was collected from April 2013 to April 2015, following 24 h incubations under ambient light and temperature.

Mentions: Dinitrogen (N2) fixation rates exhibited a seasonal variability similar to that measured for heterotrophic bacterial abundance and bacterial production (Fig 4). The lowest N2 fixation rates were measured during spring and autumn, ranging between 0.1 and 0.2 nmol N L-1 d-1 (Fig 4). In contrast, 2–4 fold higher N2 fixation rates were recorded during the winter and early summer (~0.4 nmol N L-1 d-1, Fig 4), concurrent with the temporal dynamics of bacterial abundance and bacterial production temporal dynamics (Fig 3). New production due to N2 fixation equaled 10± 7% of the total primary production, with a larger contribution during wintertime (>8%) and the smallest contribution during autumn (<3%).


The Temporal Dynamics of Coastal Phytoplankton and Bacterioplankton in the Eastern Mediterranean Sea.

Raveh O, David N, Rilov G, Rahav E - PLoS ONE (2015)

The temporal dynamics of N2 fixation in the coastal eastern Mediterranean Sea.Data was collected from April 2013 to April 2015, following 24 h incubations under ambient light and temperature.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608699&req=5

pone.0140690.g004: The temporal dynamics of N2 fixation in the coastal eastern Mediterranean Sea.Data was collected from April 2013 to April 2015, following 24 h incubations under ambient light and temperature.
Mentions: Dinitrogen (N2) fixation rates exhibited a seasonal variability similar to that measured for heterotrophic bacterial abundance and bacterial production (Fig 4). The lowest N2 fixation rates were measured during spring and autumn, ranging between 0.1 and 0.2 nmol N L-1 d-1 (Fig 4). In contrast, 2–4 fold higher N2 fixation rates were recorded during the winter and early summer (~0.4 nmol N L-1 d-1, Fig 4), concurrent with the temporal dynamics of bacterial abundance and bacterial production temporal dynamics (Fig 3). New production due to N2 fixation equaled 10± 7% of the total primary production, with a larger contribution during wintertime (>8%) and the smallest contribution during autumn (<3%).

Bottom Line: Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates.Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients.These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.

View Article: PubMed Central - PubMed

Affiliation: National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa, Israel.

ABSTRACT
This study considers variability in phytoplankton and heterotrophic bacterial abundances and production rates, in one of the most oligotrophic marine regions in the world-the Levantine Basin. The temporal dynamics of these planktonic groups were studied in the coastal waters of the southeastern Mediterranean Sea approximately every two weeks for a total of two years. Heterotrophic bacteria were abundant mostly during late summer and midwinter, and were positively correlated with bacterial production and with N2 fixation. Based on size fractionating, picophytoplankton was abundant during the summer, whereas nano-microphytoplankton predominated during the winter and early spring, which were also evident in the size-fractionated primary production rates. Autotrophic abundance and production correlated negatively with temperature, but did not correlate with inorganic nutrients. Furthermore, a comparison of our results with results from the open Levantine Basin demonstrates that autotrophic and heterotrophic production, as well as N2 fixation rates, are considerably higher in the coastal habitat than in the open sea, while nutrient levels or cell abundance are not different. These findings have important ecological implications for food web dynamics and for biological carbon sequestration in this understudied region.

No MeSH data available.