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Increasing nitrogen limitation in the Bothnian Sea, potentially caused by inflow of phosphate-rich water from the Baltic Proper.

Rolff C, Elfwing T - Ambio (2015)

Bottom Line: This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water.The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water.The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms.

View Article: PubMed Central - PubMed

Affiliation: Stockholm University Baltic Sea Centre, 106 91, Stockholm, Sweden. carl.rolff@su.se.

ABSTRACT
The study showed that the open water of the Bothnian Sea (BS) is likely to have shifted from altering nitrogen and phosphorous limitations of the spring bloom to more nitrogen-limited conditions during the last 20 years. This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water. The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water. The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms. There does not appear to be any immediate concern in the short-term perspective for the state of the BS, but a progression of the processes may lead to a more eutrophic state of the BS.

No MeSH data available.


Related in: MedlinePlus

Long-term basin estimates of Φ (mean and SD) in winter surface water (November–December, 0–20 m) in the basins nBP, ÅS, BS, and BB using data from the winter cruise of the SMHI. Balanced nutrients (Φ = 0) indicated
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Fig2: Long-term basin estimates of Φ (mean and SD) in winter surface water (November–December, 0–20 m) in the basins nBP, ÅS, BS, and BB using data from the winter cruise of the SMHI. Balanced nutrients (Φ = 0) indicated

Mentions: A clear south-to-north gradient of Φ was found in the long-term analysis using all data available for surface water (0–20 m), going from strong nitrogen limitation in the nBP to strong phosphorous limitation in the BB (Fig. 2). The potential nutrient limitations differed distinctly between the basins BB, BS, and nBP, whereas the ÅS resembled the nBP (Fig. 2). In the nBP, winter values of Φ were strongly negative, indicating a strong nitrogen limitation of the spring bloom (lower quartile Q25 = −3.9 and upper quartile Q75 = −2.3 μmol N L−1). The ÅS showed slightly less negative values of Φ (Q25 = −2.4 and Q75 = −0.8 μmol N L−1). In the BS, the pattern was different and centered around nutrient balance of Φ = 0 (Q25 = −0.8 and Q75 = 0.26 μmol N L−1). The BB showed a clear surplus of nitrogen indicated by strongly positive values of Φ (Q25 = 4.9 and Q75 = 5.4 μmol N L−1). In the nBP, ÅS, and to some extent in the BS, Φ showed no clear temporal trend from 1969 to 2000 but an abrupt development toward stronger nitrogen limitation after 2000. In approximate terms, Φ in the nBP declined from −3 to −5 μmol N L−1 and in the ÅS from −1 to −4 μmol N L−1, whereas Φ in the BS changed from values around 0 to −1.5 μmol N L−1. The changes were the most pronounced in the nBP and ÅS with a weaker trend in the BS, whereas no long-term temporal trend was evident in the BB.Fig. 2


Increasing nitrogen limitation in the Bothnian Sea, potentially caused by inflow of phosphate-rich water from the Baltic Proper.

Rolff C, Elfwing T - Ambio (2015)

Long-term basin estimates of Φ (mean and SD) in winter surface water (November–December, 0–20 m) in the basins nBP, ÅS, BS, and BB using data from the winter cruise of the SMHI. Balanced nutrients (Φ = 0) indicated
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4591228&req=5

Fig2: Long-term basin estimates of Φ (mean and SD) in winter surface water (November–December, 0–20 m) in the basins nBP, ÅS, BS, and BB using data from the winter cruise of the SMHI. Balanced nutrients (Φ = 0) indicated
Mentions: A clear south-to-north gradient of Φ was found in the long-term analysis using all data available for surface water (0–20 m), going from strong nitrogen limitation in the nBP to strong phosphorous limitation in the BB (Fig. 2). The potential nutrient limitations differed distinctly between the basins BB, BS, and nBP, whereas the ÅS resembled the nBP (Fig. 2). In the nBP, winter values of Φ were strongly negative, indicating a strong nitrogen limitation of the spring bloom (lower quartile Q25 = −3.9 and upper quartile Q75 = −2.3 μmol N L−1). The ÅS showed slightly less negative values of Φ (Q25 = −2.4 and Q75 = −0.8 μmol N L−1). In the BS, the pattern was different and centered around nutrient balance of Φ = 0 (Q25 = −0.8 and Q75 = 0.26 μmol N L−1). The BB showed a clear surplus of nitrogen indicated by strongly positive values of Φ (Q25 = 4.9 and Q75 = 5.4 μmol N L−1). In the nBP, ÅS, and to some extent in the BS, Φ showed no clear temporal trend from 1969 to 2000 but an abrupt development toward stronger nitrogen limitation after 2000. In approximate terms, Φ in the nBP declined from −3 to −5 μmol N L−1 and in the ÅS from −1 to −4 μmol N L−1, whereas Φ in the BS changed from values around 0 to −1.5 μmol N L−1. The changes were the most pronounced in the nBP and ÅS with a weaker trend in the BS, whereas no long-term temporal trend was evident in the BB.Fig. 2

Bottom Line: This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water.The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water.The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms.

View Article: PubMed Central - PubMed

Affiliation: Stockholm University Baltic Sea Centre, 106 91, Stockholm, Sweden. carl.rolff@su.se.

ABSTRACT
The study showed that the open water of the Bothnian Sea (BS) is likely to have shifted from altering nitrogen and phosphorous limitations of the spring bloom to more nitrogen-limited conditions during the last 20 years. This is affected by the by inflow of phosphate-rich and oxygen-depleted water from depths near the halocline in the northern Baltic Proper, where severe oxygen conditions currently cause extreme phosphate concentrations in the deep water. The change in relation between inorganic nitrogen and phosphorous in the BS occurs first in the deep water and then progresses to the surface water. The change can potentially cause increased production in the BS and more frequent cyanobacterial blooms. There does not appear to be any immediate concern in the short-term perspective for the state of the BS, but a progression of the processes may lead to a more eutrophic state of the BS.

No MeSH data available.


Related in: MedlinePlus