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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 seasonal surface (2 m) variability of temperature (open circle) and salinity (black circle).Data were collected between April 2013 and April 2015 at the study site off the eastern Mediterranean coast.
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pone.0140690.g001: The seasonal surface (2 m) variability of temperature (open circle) and salinity (black circle).Data were collected between April 2013 and April 2015 at the study site off the eastern Mediterranean coast.

Mentions: The seasonal characteristics of temperature and of inorganic nutrients in the nearshore waters of Tel Shikmona between April 2013 and April 2015 are shown in Fig 1 and Table 1. Temperatures were as low as ~16°C in wintertime (January and February of 2014 and 2015) and increased to >30°C during the summer months (August and September of 2013 and 2014). The level of salinity did not exhibit any distinct seasonal variability and was usually > 39.0 PSU, except during the winter of 2015 when lower salinity levels were recorded (Fig 1). The concentrations of inorganic nutrients (e.g., nitrate+ nitrite, phosphorus, and silicic acid) throughout the study period were in the nano-molar range and did not reveal any distinct seasonal trends (Table 1). Dissolved NO2+NO3 were low (0.20± 0.11 μM) overall, especially during the early summer and autumn of 2014 (<0.10 μM), though they were somewhat higher during January and February of 2015 (> 1 μM). Phosphorus concentrations were low throughout the sampling period (0.02± 0.01 μM), with the highest concentrations measured during both winters (~0.08 μM) and the lowest measured at the end of both summers (below the detection limit). Exceptionally high phosphate concentrations were recorded following a sewage effluent discharge during February 2015 (Table 1). The concentration of silicic acid (Si(OH)4) was the lowest during midwinter (February 2014, 0.30 μM) and the highest during June 2014 (2.39 μM).


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 seasonal surface (2 m) variability of temperature (open circle) and salinity (black circle).Data were collected between April 2013 and April 2015 at the study site off the eastern Mediterranean coast.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0140690.g001: The seasonal surface (2 m) variability of temperature (open circle) and salinity (black circle).Data were collected between April 2013 and April 2015 at the study site off the eastern Mediterranean coast.
Mentions: The seasonal characteristics of temperature and of inorganic nutrients in the nearshore waters of Tel Shikmona between April 2013 and April 2015 are shown in Fig 1 and Table 1. Temperatures were as low as ~16°C in wintertime (January and February of 2014 and 2015) and increased to >30°C during the summer months (August and September of 2013 and 2014). The level of salinity did not exhibit any distinct seasonal variability and was usually > 39.0 PSU, except during the winter of 2015 when lower salinity levels were recorded (Fig 1). The concentrations of inorganic nutrients (e.g., nitrate+ nitrite, phosphorus, and silicic acid) throughout the study period were in the nano-molar range and did not reveal any distinct seasonal trends (Table 1). Dissolved NO2+NO3 were low (0.20± 0.11 μM) overall, especially during the early summer and autumn of 2014 (<0.10 μM), though they were somewhat higher during January and February of 2015 (> 1 μM). Phosphorus concentrations were low throughout the sampling period (0.02± 0.01 μM), with the highest concentrations measured during both winters (~0.08 μM) and the lowest measured at the end of both summers (below the detection limit). Exceptionally high phosphate concentrations were recorded following a sewage effluent discharge during February 2015 (Table 1). The concentration of silicic acid (Si(OH)4) was the lowest during midwinter (February 2014, 0.30 μM) and the highest during June 2014 (2.39 μM).

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.