Contribution of Rhizosolenia eriensis and Cyclotella spp. to the Deep Chlorophyll Maximum of Sproat Lake, British Columbia, Canada

1990 ◽  
Vol 47 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Leland J. Jackson ◽  
John G. Stockner ◽  
Paul J. Harrison
Keyword(s):  
Spatial Separation ◽  
Deep Chlorophyll Maximum ◽  
Nitrogen And Phosphorus ◽  
Low Light ◽  
Temporal And Spatial Distribution ◽  
Neutral Buoyancy ◽  
Chlorophyll Maximum ◽  
Centric Diatoms ◽  
Temporal And Spatial ◽  
Lake Fertilization

Experimental fertilization of Sproat Lake with nitrogen and phosphorus greatly increased the abundance of two centric diatoms: Cyclotella spp. and Rhizosolenia eriensis. A decrease in sinking rates to neutral buoyancy at 17.5–22.5 m, an area of high nutrients and low light, coupled with sedimentation estimates of 106–107 celis∙m−2∙d−1, provide strong evidence that diatoms contribute to the formation of a seasonal deep chlorophyll maximum (DCM). The position of the Sproat Lake DCM, occurring at or just above the 1% light depth, appears to be largely determined by the light regime. R. eriensis bloomed and sank out of the mixed layer early in the spring before lake fertilization began. Immediately after fertilization, concentrations of nitrate and phosphate were elevated for 1 h only in the top 1 m of the water column. Most R. eriensis cells were well below 1 m and benefited little from the nutrient addition because of temporal and spatial separation. Cyclotella spp. occurred in the upper epilimnion and bloomed later in the year and consequently benefited (by large density increases) from fertilization. It is important to consider the temporal and spatial distribution of phytoplankton in determining which species will increase in abundance as a result of areal fertilization.

scholarly journals Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum

2020 ◽  
Vol 15 (1) ◽  
pp. 359-362
Author(s):  
Nicholas J. Hawco ◽  
Feixue Fu ◽  
Nina Yang ◽  
David A. Hutchins ◽  
Seth G. John
Keyword(s):  
Light Intensity ◽  
High Efficiency ◽  
Iron Concentration ◽  
Euphotic Zone ◽  
Theoretical Models ◽  
Light Limitation ◽  
Deep Chlorophyll Maximum ◽  
North Pacific Subtropical Gyre ◽  
Low Light ◽  
Chlorophyll Maximum

AbstractThroughout the open ocean, a minimum in dissolved iron concentration (dFe) overlaps with the deep chlorophyll maximum (DCM), which marks the lower limit of the euphotic zone. Maximizing light capture in these dim waters is expected to require upregulation of Fe-bearing photosystems, further depleting dFe and possibly leading to co-limitation by both iron and light. However, this effect has not been quantified for important phytoplankton groups like Prochlorococcus, which contributes most of the productivity in the oligotrophic DCM. Here, we present culture experiments with Prochlorococcus strain MIT1214, a member of the Low Light 1 ecotype isolated from the DCM in the North Pacific subtropical gyre. Under a matrix of iron and irradiance matching those found at the DCM, the ratio of Fe to carbon in Prochlorococcus MIT1214 cells ranged from 10–40 × 10−6 mol Fe:mol C and increased with light intensity and growth rate. These results challenge theoretical models predicting highest Fe:C at lowest light intensity, and are best explained by a large photosynthetic Fe demand that is not downregulated at higher light. To sustain primary production in the DCM with the rigid Fe requirements of low-light-adapted Prochlorococcus, dFe must be recycled rapidly and at high efficiency.

Temporal and Spatial Distribution Characteristics of Nitrogen and Phosphorus in Soil with Typical Crops Planted on in Headwater Region of Liao He

2013 ◽  
Vol 765-767 ◽  
pp. 2967-2970
Author(s):  
Ying Xiong ◽  
Wen Long Lu ◽  
Ping Guo ◽  
Zhong Lei Xie ◽  
Wei Wei Guo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Nitrogen Content ◽  
Surface Soil ◽  
Ammonia Nitrogen ◽  
Available Phosphorus ◽  
Nitrogen And Phosphorus ◽  
Temporal And Spatial Distribution ◽  
Bottom Soil ◽  
Spatial Distribution Characteristics ◽  
Temporal And Spatial

This paper discusses the temporal and spatial distribution of nitrogen, phosphorus in the soil with typical crops planted on in Headwater Region of Liao He. The purpose is to provide theoretical basis for the prediction of the non-point source pollution and protection of the environment in Headwater Region of Liao He. The results show that the content of the substance which can be absorbed by plants was higher in the surface soil than that in the bottom soil. The nitrate nitrogen content in soil was lower in autumn than that in spring except normal planting surface soil. And the ammonia nitrogen content was also a little lower in autumn than that in spring except normal planting surface soil and blank control land 1. In autumn, the hydrolyzable nitrogen content in the surface soil was decreased slightly and it was nearly unchanged in the bottom soil. The total nitrogen content was higher in autumn. The content of available phosphorus was a little higher or nearly unchanged in autumn than that in spring, the content of total phosphorus changed irregularly.

Effect of Nutrient Additions on Lower Trophic Levels of an Oligotrophic Lake with a Seasonal Deep Chlorophyll Maximum

1990 ◽  
Vol 47 (2) ◽  
pp. 262-273 ◽  
Author(s):  
Ken S. Shortreed ◽  
John G. Stockner
Keyword(s):  
Inorganic Nitrogen ◽  
Euphotic Zone ◽  
Fold Increase ◽  
Trophic Levels ◽  
Deep Chlorophyll Maximum ◽  
Nitrogen And Phosphorus ◽  
Chlorophyll Maximum ◽  
Nutrient Additions ◽  
Prominent Component ◽  
Dominant Member

Inorganic nitrogen and phosphorus were added to the surface of selected areas of Sproat Lake, Vancouver Island, British Columbia for varying periods in 1985 and 1986. The lake is monomictic, oligotrophic, and for much of each year has a deep chlorophyll maximum (DCM) located near the bottom of the euphotic zone (20–25 m). Epilimnetic chlorophyll concentrations are low (ca. 0.5 μg∙L−1) in summer, and DCM concentrations are from three to 10 times higher. The diatom Rhizosolenia eriensis was a dominant species in the epilimnion in spring and at the DCM for much of the year, but was rare in the epilimnion during summer, and consequently was not affected by the nutrient additions. Cyclotella spp. were also abundant in spring, were a prominent component of the DCM, and increased in abundance during nutrient additions. The cyanobacterium Synechococcus was the dominant member of the autotrophic picoplankton community and during the nutrient additions densities reached 300 000∙mL−1 (a 10-fold increase). Bacterioplankton numbers also increased during nutrient additions, at times exceeding 3.0 × 106∙mL−1. The DCM was formed and maintained by sinking cells, by occasional active photosynthesis at the DCM, and by an increase in chlorophyll/cell.

scholarly journals Siderophores as an iron source for Prochlorococcus in deep chlorophyll maximum layers of the oligotrophic ocean

2021 ◽  
Author(s):  
Shane L Hogle ◽  
Thomas Hackl ◽  
Randelle M Bundy ◽  
Jiwoon Park ◽  
Brandon Satinsky ◽  
...  
Keyword(s):  
Trace Metal ◽  
Iron Uptake ◽  
Global Ocean ◽  
Deep Chlorophyll Maximum ◽  
Iron Stress ◽  
Selective Force ◽  
Low Light ◽  
Selective Pressures ◽  
Chlorophyll Maximum ◽  
Content Variation

Prochlorococcus is one of the most abundant photosynthesizing organisms in the oligotrophic oceans. Gene content variation among Prochlorococcus populations in separate ocean basins often mirrors the selective pressures imposed by the region's distinct biogeochemistry. By pairing genomic datasets with trace metal concentrations from across the global ocean, we show that the genomic capacity for siderophore-mediated iron uptake is widespread in low-light adapted Prochlorococcus populations from iron-depleted regions of the oligotrophic Pacific and S. Atlantic oceans: Prochlorococcus siderophore consumers were absent in the N. Atlantic ocean (higher iron flux) but constituted up to half of all Prochlorococcus genomes from metagenomes in the N. Pacific (lower iron flux). Prochlorococcus siderophore consumers, like many other bacteria with this trait, also lack siderophore biosynthesis genes indicating that they scavenge exogenous siderophores from seawater. Statistical modeling suggests that the capacity for siderophore uptake is endemic to remote ocean regions where atmospheric iron fluxes are the smallest, particularly at deep chlorophyll maximum and primary nitrite maximum layers. We argue that abundant siderophore consumers at these two common oceanographic features could be a symptom of wider community iron stress, consistent with prior hypotheses. Our results provide a clear example of iron as a selective force driving the evolution of Prochlorococcus.

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