scholarly journals Increased Nitrogen Loading Boosts Summer Phytoplankton Growth by Alterations in Resource and Zooplankton Control: A Mesocosm Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Hu He ◽  
Kunquan Chen ◽  
Yingxun Du ◽  
Kuanyi Li ◽  
Zhengwen Liu ◽  
...  
Keyword(s):  
Shallow Lakes ◽  
Phytoplankton Biomass ◽  
Nitrogen Loading ◽  
Phytoplankton Growth ◽  
N Addition ◽  
Eutrophic Lakes ◽  
Benthivorous Fish ◽  
Subtropical Lakes ◽  
Strategic Approach ◽  
N Loading

The effectiveness of controlling nitrogen (N) to manage eutrophication of aquatic ecosystems remains debated. To understand the mechanisms behind phytoplankton growth in shallow lakes (resource and grazing effects) under contrasting N loading scenarios, we conducted a 70-days mesocosm experiment in summer. The mesocosms contain natural plankton communities deriving from a 10-cm layer of lake sediment and 450 L of lake water. We also added two juvenile crucian carp (Carassius carassius) in each mesocosm to simulate presence of the prevailing omni-benthivorous fish in subtropical lakes. Our results showed that N addition increased not only water N levels but also total phosphorus (TP) concentrations, which together elevated the phytoplankton biomass and caused strong dominance of cyanobacteria. Addition of N significantly lowered the herbivorous zooplankton to phytoplankton biomass ratio and promoted the phytoplankton yield per nutrient (Chl-a: TP or Chl-a: TN ratio), indicating that summer N addition likely also favored phytoplankton growth through reduced grazing by zooplankton. Accordingly, our study indicates that summer N loading may boost eutrophication via both changes in resource and grazing control in shallow lakes. Thus, alleviation of eutrophication in shallow eutrophic lakes requires a strategic approach to control both nutrients (N and P) appropriately.

scholarly journals Effects of Diversity, Coverage and Biomass of Submerged Macrophytes on Nutrient Concentrations, Water Clarity and Phytoplankton Biomass in Two Restored Shallow Lakes

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1425 ◽  
Author(s):  
Yiming Gao ◽  
Chunyu Yin ◽  
Yu Zhao ◽  
Zhengwen Liu ◽  
Pingping Liu ◽  
...  
Keyword(s):  
Water Quality ◽  
Shallow Lakes ◽  
Phytoplankton Biomass ◽  
Submerged Macrophytes ◽  
Myriophyllum Spicatum ◽  
Water Clarity ◽  
Nutrient Concentrations ◽  
Biomass Density ◽  
Effective Measure ◽  
Subtropical Lakes

Transplantation of submerged macrophytes to restore shallow lakes has been used as an effective measure to maintain a clear water state. Water quality is highly correlated with submerged macrophytes community, however, the relationships between water quality and the diversity, coverage and biomass of submerged macrophytes are, so far, not yet well studied. We analyzed the correlations of nutrient concentrations, water clarity and phytoplankton biomass with the metrics of submerged macrophytes community in two Chinese restored shallow subtropical lakes, Lake Wuli (Wuli-E, 5 ha) and Lake Qinhu (Qin-E, 8 ha). A similar biomass of submerged macrophytes was transplanted into each lake, while both the species richness and coverage of macrophytes in Qin-E were lower than Wuli-E. After a 1–2-year restoration, the diversity almost had no change, but the biomass density and coverage decreased in Wuli-E. As for Qin-E, the coverage of submerged macrophytes increased but biomass density and diversity decreased. The dominance of canopy-forming submerged macrophyte species Myriophyllum spicatum was observed in Qin-E and less meadow-forming biomass and species was observed than that in Wuli-E. Moreover, it was also observed that Wuli-E had a better water quality than that of Qin-E after transplantation. Path analysis results showed that macrophyte coverage and the diversity related to meadow-forming species (e.g., Vallisneria spinulosa) had strong effects on enhancing clarity and reducing nutrient concentrations. But the high biomass density accompanied by the canopy-forming species like M. spicatum was unfavorable for controlling nutrients. Our results provide important insight into the different roles that macrophyte diversity, biomass and coverage play in improving water clarity and controlling nutrient concentrations. This new knowledge will be instrumental in implementing more effective lake restoration, especially using macrophyte transplantation as a restoration tool in warm shallow lakes.

Resuspension of algal cells by benthivorous fish boosts phytoplankton biomass and alters community structure in shallow lakes

2007 ◽  
Vol 52 (6) ◽  
pp. 977-987 ◽  
Author(s):  
FRANK C. J. M. ROOZEN ◽  
MIQUEL LÜRLING ◽  
HANNEKE VLEK ◽  
EDWIN A. J. VAN DER POUW KRAAN ◽  
BAS W. IBELINGS ◽  
...  
Keyword(s):  
Community Structure ◽  
Shallow Lakes ◽  
Phytoplankton Biomass ◽  
Benthivorous Fish

Study on the mutual interactions between the parameters of a CANON system and its coping strategy when operating at room temperature (15 to 25 °C) using response surface methodology

2014 ◽  
Vol 69 (9) ◽  
pp. 1805-1812 ◽  
Author(s):  
Jian Zhou ◽  
Guangxu Qin ◽  
Jianbing Zhang ◽  
Yancheng Li ◽  
Qiang He ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Removal Efficiency ◽  
Coping Strategy ◽  
Room Temperature ◽  
Loading Rate ◽  
Nitrogen Loading ◽  
Independent Variables ◽  
Do Concentration ◽  
N Loading

The coping strategy of a CANON (completely autotrophic nitrogen removal over nitrite) reactor working at room temperature was investigated using response surface methodology. The total nitrogen (TN) removal efficiency was taken as a dependent variable. The temperature (X), dissolved oxygen (DO) concentration (Y), and influent nitrogen loading rate (Z) were taken as independent variables. Results showed that the relation of these three independent variables can be described by the TN removal efficiency expressed as −5.03 + 1.51X + 45.16Y + 30.13Z + 0.26XY + 1.84XZ − 0.04X2 − 9.06Y2 − 99.00Z2. The analysis of variance proved that the equation is applicable. The response surface demonstrated that the temperature significantly interacts with the DO concentration and influent N loading rate. A coping strategy for the CANON reactor working at room temperature is thus proposed: altering the DO concentration and the N loading rate to counterbalance the impact of low temperature. The verification test proved the strategy is viable. The TN removal efficiency was 91.3% when the reactor was operated under a temperature of 35.0 °C, a DO of 3.0 mg/L, and a N loading rate of 0.70 kgN/(m³ d). When the temperature dropped from 35.0 to 19.2 °C, the TN removal efficiency was kept at 88.7% by regulating the influent N loading rate from 0.7 kgN/(m³ d) to 0.35 kgN/(m³ d) and the DO concentration from 3.0 to 2.6 mg/L.

Analysis of within- and between-day chlorophyll-a dynamics in Mantua Superior Lake, with a continuous spectroradiometric measurement

2013 ◽  
Vol 64 (4) ◽  
pp. 303 ◽  
Author(s):  
M. Bresciani ◽  
M. Rossini ◽  
G. Morabito ◽  
E. Matta ◽  
M. Pinardi ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Continuous Monitoring ◽  
Phytoplankton Growth ◽  
Key Factors ◽  
Eutrophic Lakes ◽  
Chl A ◽  
Metabolic Adaptations ◽  
Horizontal Migration ◽  
Radiometric System ◽  
Growth Distribution

Eutrophic lakes display unpredictable patterns of phytoplankton growth, distribution, vertical and horizontal migration, likely depending on environmental conditions. Monitoring chlorophyll-a (Chl-a) concentration provides reliable information on the dynamics of primary producers if monitoring is conducted frequently. We present a practical approach that allows continuous monitoring of Chl-a concentration by using a radiometric system that measures optical spectral properties of water. We tested this method in a shallow, nutrient-rich lake in northern Italy, the Mantua Superior Lake, where the radiometric system collected data all throughout the day (i.e. every 5 min) for ~30 days. Here, specifically developed algorithms were used to convert water reflectance to Chl-a concentration. The best performing algorithm (R2 = 0.863) was applied to a larger dataset collected in September 2011. We characterised intra- and inter-daily Chl-a concentration dynamics and observed a high variability; during a single day, Chl-a concentration varied from 20 to 130 mg m–3. Values of Chl-a concentration were correlated with meteo-climatic parameters, showing that solar radiance and wind speed are key factors regulating the daily phytoplankton growth and dynamics. Such patterns are usually determined by vertical migration of different phytoplankton species within the water column, as well as by metabolic adaptations to changes in light conditions.

Phytoplankton biomass and chlorophyll-a in some shallow lakes in central Europe

Hydrobiologia ◽  
1991 ◽  
Vol 215 (2) ◽  
pp. 111-119 ◽  
Author(s):  
Lajos Vörös ◽  
Judit Padisák
Keyword(s):  
Chlorophyll A ◽  
Central Europe ◽  
Shallow Lakes ◽  
Phytoplankton Biomass

scholarly journals Cyanobacterial blooms in shallow lakes of the Iławskie Lake District

2011 ◽  
Vol 11 (2) ◽  
pp. 69-79 ◽  
Author(s):  
Ewa Dembowska
Keyword(s):  
Green Algae ◽  
Trophic Level ◽  
Shallow Lakes ◽  
Algal Blooms ◽  
Catchment Area ◽  
Cyanobacterial Blooms ◽  
Lake District ◽  
Eutrophic Lakes ◽  
Blue Green Algae ◽  
Catchment Areas

Cyanobacterial blooms in shallow lakes of the Iławskie Lake DistrictThe dominance of blue-green algae observed in many lakes is related to a high trophic level. Shallow eutrophic lakes are particularly often abundant in blue-green algae. The research on phytoplankton, the results of which are presented in this paper, was carried out between 2002 and 2005 in six lakes. These lakes differed considerably in their size and management methods applied in the catchment (drainage) area. A few types of water blooms were distinguished, which is related to the catchment area management, the intensity of mixing and the trophic level. Algal blooms of the Planktothrix type appeared in lakes situated in an open area of agricultural catchment basins. Algal blooms of the Limnothrix type were characteristic of lakes with a forest-agricultural catchment area but surrounded by high shores, which reduced the wind influence on the mixing. Sporadic mixed algal blooms were typical of lakes situated in forest catchment areas.

scholarly journals Evaluating Soil–Root Interaction of Hybrid Larch Seedlings Planted under Soil Compaction and Nitrogen Loading

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 947
Author(s):  
Tetsuto Sugai ◽  
Satoko Yokoyama ◽  
Yutaka Tamai ◽  
Hirotaka Mori ◽  
Enrico Marchi ◽  
...  
Keyword(s):  
Root Development ◽  
Soil Compaction ◽  
Fine Root ◽  
Morphological Changes ◽  
Nitrogen Loading ◽  
Hybrid Larch ◽  
Soil Hardness ◽  
Hardness Change ◽  
N Loading ◽  
Soil Recovery

Although compacted soil can be recovered through root development of planted seedlings, the relationship between root morphologies and soil physical properties remain unclear. We investigated the impacts of soil compaction on planted hybrid larch F1 (Larix gmelinii var. japonica×L. kaempferi, hereafter F1) seedlings with/without N loading. We assumed that N loading might increase the fine root proportion of F1 seedlings under soil compaction, resulting in less effects of root development on soil recovery. We established experimental site with different levels of soil compaction and N loading, where two-year-old F1 seedlings were planted. We used a hardness change index (HCI) to quantify a degree of soil hardness change at each depth. We evaluated root morphological responses to soil compaction and N loading, focusing on ectomycorrhizal symbiosis. High soil hardness reduced the total dry mass of F1 seedlings by more than 30%. Significant positive correlations were found between HCI and root proportion, which indicated that F1 seedling could enhance soil recovery via root development. The reduction of fine root density and its proportion due to soil compaction was observed, while these responses were contrasting under N loading. Nevertheless, the relationships between HCI and root proportion were not changed by N loading. The relative abundance of the larch-specific ectomycorrhizal fungi under soil compaction was increased by N loading. We concluded that the root development of F1 seedling accelerates soil recovery, where N loading could induce root morphological changes under soil compaction, resulting in the persistent relationship between root development and soil recovery.

scholarly journals Vertical mixing, critical depths, and phytoplankton growth in the Ross Sea

2014 ◽  
Vol 72 (6) ◽  
pp. 1952-1960 ◽  
Author(s):  
Walker O. Smith ◽  
Randolph M. Jones
Keyword(s):  
Water Column ◽  
Mixed Layer ◽  
Phytoplankton Biomass ◽  
Ross Sea ◽  
Vertical Mixing ◽  
Biomass Accumulation ◽  
Phytoplankton Growth ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
Mixed Layers

Abstract Phytoplankton growth and biomass accumulation vary spatially and temporally in the Ross Sea, largely as a function of ice concentrations, vertical mixing depths, and iron concentrations. To assess the role of vertical mixing in bloom initiation, we used a high-resolution numerical model to estimate changes in mixed layer depths from October 1 through early December, the period where phytoplankton growth begins and biomass accumulates, and estimate critical depths for this period. Mixed layers in October ranged from the complete water column (>600 m) to ca. 200 m; over a 60-day period, the mixed layers decreased on average by 70%. Estimated critical depths were exceeded in October, but would allow growth to proceed in late October due to shoaling of mixed layer depths, consistent with the known onset of the spring bloom in the Ross Sea. We also analysed a series of stations sampled near the Ross Ice Shelf during January 2012. Mean vertical profiles for the stations indicated deep vertical mixing; mixed layer depths averaged 60 m and ranged up to 96 m. Chlorophyll concentrations within the mixed layer averaged 6.60 µg l−1, and the pigment contributions were dominated by Phaeocystis antarctica. We suggest that this mesoscale region near the ice shelf is elevated in phytoplankton biomass due to frequent mixing events that redistribute biomass to depth and replenish nutrients, which in turn are utilized by an assemblage capable of utilizing low mean irradiance levels. Thus, the deep mixed layers and high biomass concentrations represent growth over long periods under reduced mixing punctuated by short periods of deeper vertical mixing that redistribute biomass. Water column vertical mixing and phytoplankton biomass in the Ross Sea are consistent with the critical depth concept as originally proposed by Sverdrup.

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