Vertical location of seasonal nutriclines in the western Gulf of Finland

Laanemets, Jaan; Kononen, Kaisa; Pavelson, J.; Poutanen, El

doi:10.1016/j.jmarsys.2004.03.003

Cited by 29 publications

(27 citation statements)

References 19 publications

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“…The Tvärminne area is not directly affected by large sewage outlets, but frequent upwellings during westerly winds (Niemi 1975, Laanemets et al 2004) and atmospheric deposition (see Vähätalo & Zepp 2005) introduce nutrients to the productive surface layer. The physics, chemistry, and plankton succession of the study area are well known (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…During the cyanobacterial bloom, in mid-July 2002, consistent moderate southwest -west winds caused an upwelling of nutrient-rich deep water, which is a frequently occurring phenomenon in the Tvärminne area (Niemi 1975, Laanemets et al 2004. The upwelling led to elevated mineral N and P concentrations and an inorganic N:P ratio (14) close to that of Redfield.…”

Section: Factors Controlling Bacterial Growthmentioning

confidence: 99%

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Effects of inorganic nutrients, glucose and solar radiation on bacterial growth and exploitation of dissolved organic carbon and nitrogen in the northern Baltic Sea

Lignell¹,

Hoikkala²,

Lahtinen³

2008

Aquat. Microb. Ecol.

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Factors controlling bacterial growth and degradation of dissolved organic carbon (DOC) and nitrogen (DON) in the productive surface layer were investigated during the main summer stages of phytoplankton growth in the Gulf of Finland. The effects of different combinations of ammonium, phosphate, glucose, flagellates, and sunlight pre-exposure treatments were followed for 2 to 3 wk in natural bacterial (< 0.7 µm pre-filtered) samples. Bacteria degraded the indigenous labile DOC and DON pools within 1 wk. The labile shares of total DOC and DON were <1 to 5 and 13 to 21%, respectively, and their depletion showed no important treatment effects. Nevertheless, photochemical transformations of DOC and DON (sunlight pre-treatment over 1 d) resulted in increased bacterial production. The phytoplankton system was N-limited in early summer, but showed a shift towards combined P and N deficiency during the late summer bloom of filamentous, N 2 -fixing cyanobacteria. Ambient labile DOC:DON ratios were low, increasing from <1-3 (mol mol -1 ) in early summer to 3-7 in late summer, and addition of glucose led to a significant bacterial production response. Thus, it appears that bacteria were consistently limited by the low availability of labile DOC, while phytoplankton exhausted the available free mineral nutrient pools, thereby creating a situation combining C-limited bacterial growth with mineral nutrient-limited phytoplankton growth.

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Section: Methodsmentioning

confidence: 99%

Section: Factors Controlling Bacterial Growthmentioning

confidence: 99%

Effects of inorganic nutrients, glucose and solar radiation on bacterial growth and exploitation of dissolved organic carbon and nitrogen in the northern Baltic Sea

Lignell¹,

Hoikkala²,

Lahtinen³

2008

Aquat. Microb. Ecol.

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“…For example, one definition is the depth where the nitrate concentration reaches a prescribed concentration, e.g., 0.05, 0.1, 1.0, or 12 mmol N m −3 (Cullen and Eppley, 1981;Koeve et al, 1993;Martin and Pondaven, 2003). Some studies choose it to be the first depth where nitrogen is detectable (e.g., 0.05 or 0.1 mmol N m −3 ) (Cermeno et al, 2008;Hickman et al, 2012) or where the nitrogen concentration exceeds the mixed layer value by a prescribed concentration difference (e.g., 0.05 mmol N m −3 ) (Laanemets et al, 2004). Significant differences exist between these defined depths, i.e., the depth of the maximal nitrate gradient was found to be deeper by 10 m from the first depth where nitrate can be detected (Eppley et al, 1978), while the nitrate gradient at the first detectable depth of nitrate is nearly 0 (Cermeno et al, 2008).…”

Section: Definition Of the Nitraclinementioning

confidence: 99%

“…The nitracline depth physically depends on the degree of water-column stratification and the magnitude of momentum transfer associated with wind stress (Denman and Gargett, 1983;Laanemets et al, 2004). It also depends on momentum transfer from below (Lipschultz et al, 2002) and, in some cases, vertical advection such as upwelling (Laanemets et al, 2004).…”

mentioning

confidence: 99%

“…It also depends on momentum transfer from below (Lipschultz et al, 2002) and, in some cases, vertical advection such as upwelling (Laanemets et al, 2004). However, in a relatively stable environment, the SCML may restrict the diffusive flux of nitrates to the euphotic zone and continually erode the nitracline supposing that sufficient light is available (Probyn et al, 1995).…”

mentioning

confidence: 99%

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Analytical solution of the nitracline with the evolution of subsurface chlorophyll maximum in stratified water columns

et al. 2017

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Abstract. In a stratified water column, the nitracline is a layer where the nitrate concentration increases below the nutrient-depleted upper layer, exhibiting a strong vertical gradient in the euphotic zone. The subsurface chlorophyll maximum layer (SCML) forms near the bottom of the euphotic zone, acting as a trap to diminish the upward nutrient supply. Depth and steepness of the nitracline are important measurable parameters related to the vertical transport of nitrate into the euphotic zone. The correlation between the SCML and the nitracline has been widely reported in the literature, but the analytic solution for the relationship between them is not well established. By incorporating a piecewise function for the approximate Gaussian vertical profile of chlorophyll, we derive analytical solutions of a specified nutrient-phytoplankton model. The model is well suited to explain basic dependencies between a nitracline and an SCML. The analytical solution shows that the nitracline depth is deeper than the depth of the SCML, shoaling with an increase in the light attenuation coefficient and with a decrease in surface light intensity. The inverse proportional relationship between the light level at the nitracline depth and the maximum rate of new primary production is derived. Analytic solutions also show that a thinner SCML corresponds to a steeper nitracline. The nitracline steepness is positively related to the light attenuation coefficient but independent of surface light intensity. The derived equations of the nitracline in relation to the SCML provide further insight into the important role of the nitracline in marine pelagic ecosystems.

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