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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

Monthly means of Φ (SD indicated) in surface water (0–20 m) at stations BY31 (nBP), SR5/C4 (BS), and F9/A13 (southern BB, not indicated in Fig. 1) for the years 1993–1999 when data where obtained for most years at a monthly basis
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Fig5: Monthly means of Φ (SD indicated) in surface water (0–20 m) at stations BY31 (nBP), SR5/C4 (BS), and F9/A13 (southern BB, not indicated in Fig. 1) for the years 1993–1999 when data where obtained for most years at a monthly basis

Mentions: At station BY31, Φ values reached a minimum of ~−3.8 in January and a maximum in August of ~−0.5 (Fig. 5). The January Φ values were 0.6–1.4 μmol N L−1 lower than those during November–December. This is a substantial difference in relation to the difference between the minimum and the maximum. Potential nitrogen limitations of the spring bloom are thus underestimated in the nBP and ÅS when using November–December data compared with January–February. The difference between the nBP and the other basins is thus in reality greater than that indicated in this study. At the stations in the BS and BB, the differences in the values of Φ during January–February and November–December were small, and the latter are likely to be representative of winter conditions. In the BS, the November–December data represent a minor overestimate (~0.3 μmol N L−1) of Φ compared to February data, but only ~0.15 μmol N L−1 compared to January values. The February data were only available for 3 years in the time series.Fig. 4


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)

Monthly means of Φ (SD indicated) in surface water (0–20 m) at stations BY31 (nBP), SR5/C4 (BS), and F9/A13 (southern BB, not indicated in Fig. 1) for the years 1993–1999 when data where obtained for most years at a monthly basis
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

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

Fig5: Monthly means of Φ (SD indicated) in surface water (0–20 m) at stations BY31 (nBP), SR5/C4 (BS), and F9/A13 (southern BB, not indicated in Fig. 1) for the years 1993–1999 when data where obtained for most years at a monthly basis
Mentions: At station BY31, Φ values reached a minimum of ~−3.8 in January and a maximum in August of ~−0.5 (Fig. 5). The January Φ values were 0.6–1.4 μmol N L−1 lower than those during November–December. This is a substantial difference in relation to the difference between the minimum and the maximum. Potential nitrogen limitations of the spring bloom are thus underestimated in the nBP and ÅS when using November–December data compared with January–February. The difference between the nBP and the other basins is thus in reality greater than that indicated in this study. At the stations in the BS and BB, the differences in the values of Φ during January–February and November–December were small, and the latter are likely to be representative of winter conditions. In the BS, the November–December data represent a minor overestimate (~0.3 μmol N L−1) of Φ compared to February data, but only ~0.15 μmol N L−1 compared to January values. The February data were only available for 3 years in the time series.Fig. 4

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