Bottom-up and top-down effects on phytoplankton functional groups in Hulun Lake, China

2021 ◽  
Vol 57 ◽  
pp. 3
Author(s):  
Chengxue Ma ◽  
Chang Zhao ◽  
Patteson Chula Mwagona ◽  
Ziyu Li ◽  
Zixuan Liu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Phytoplankton Biomass ◽  
Eutrophic Lake ◽  
Positive Influence ◽  
Freshwater Ecosystems ◽  
Top Down ◽  
Bottom Up ◽  
Physical Chemical ◽  
Phytoplankton Functional Groups ◽  
Negative Effect

The debates about the extent to which phytoplankton in freshwater ecosystems are regulated by top-down or bottom-up forces have been ongoing for decades. This study examines the effects of bottom-up and top-down factors on the phytoplankton functional groups in a eutrophic lake. Phytoplankton and zooplankton were sampled and physical-chemical variables measured from May 2019 to October 2019 in Lake Hulun, China. Approximately 43 phytoplankton species were observed and grouped into 23 functional groups. For the zooplankton, about 27 species were observed and classified into 8 functional groups. The study revealed that the bottom-up effects of physical-chemical variables on some phytoplankton functional groups was stronger than the top-down effects of zooplankton. Water temperature (WT), total phosphorus (TP), total nitrogen (TN), conductivity (Cond), water transparency (SD), and dissolved oxygen (DO) significant influence the biomass of the phytoplankton functional groups. The biomass of phytoplankton functional groups was influenced positively by nutrient availability likely because nutrients influence the growth and reproduction of phytoplankton in freshwater. WT and DO had a positive influence on biomass of phytoplankton functional groups. Conversely, phytoplankton biomass revealed a decreasing trend when SD and Cond significantly increased. This study showed that zooplankton functional groups were positively correlated with phytoplankton biomass implying that the top-down control of phytoplankton by the zooplankton in the lake is not strong enough to produce a negative effect. It is evident that the zooplankton functional groups in Lake Hulun are controlled more by bottom-up force than top-down.

scholarly journals Driving forces of the diel distribution of phytoplankton functional groups in a shallow tropical lake (Lake Monte Alegre, Southeast Brazil)

2009 ◽  
Vol 69 (1) ◽  
pp. 75-85 ◽  
Author(s):  
LM. Rangel ◽  
LHS. Silva ◽  
MS. Arcifa ◽  
A. Perticarrari
Keyword(s):  
Vertical Distribution ◽  
Functional Groups ◽  
Rainy Season ◽  
Phytoplankton Biomass ◽  
Driving Forces ◽  
Circulation Pattern ◽  
Dry Period ◽  
Phytoplankton Functional Groups ◽  
The Vertical Distribution ◽  
Cool Dry Season

Phytoplankton vertical and diel dynamics in a small shallow lake (Lake Monte Alegre, Ribeirão Preto, state of São Paulo) were investigated in two climatological periods: July 2001 (cool-dry season) and March 2002 (warm-rainy season). Monte Alegre is a eutrophic reservoir, with a warm polymictic discontinuous circulation pattern. The lake was thermally stratified in both periods, although dissolved oxygen varied less in the cool-dry period. Phytoplankton biomass was higher in the warm-rainy season and the vertical distribution was stratified in both seasons. Flagellate groups (Lm, Y, W1 and W2) and functional groups typical of shallow eutrophic environments (J, X1 and Sn) were important throughout the study period. The lake's thermal pattern strongly influenced the vertical distribution of the phytoplankton community in both periods. Biomass, functional groups and size classes of phytoplankton also were determined by the presence of more efficient herbivores in the lake, especially during the cool-dry period when phytoplankton biomass decreased.

scholarly journals Phytoplankton functional groups in a tropical reservoir in the Brazilian semiarid region

2017 ◽  
Vol 65 (3) ◽  
pp. 1129
Author(s):  
Ruceline Paiva Melo Lins ◽  
Beatriz Susana Ovruski de Ceballos ◽  
Luiz Carlos Serramo Lopez ◽  
Luciana Gomes Barbosa
Keyword(s):  
Functional Groups ◽  
Environmental Conditions ◽  
Phytoplankton Biomass ◽  
Fish Farming ◽  
Semiarid Region ◽  
Monthly Basis ◽  
Brazilian Semiarid ◽  
Phytoplankton Functional Groups ◽  
Abiotic Variables ◽  
Density And Biomass

Phytoplankton functional groups structure and species abundance vary according to environmental conditions. The present study investigated the natural and anthropogenic stressors that affect phytoplankton functional group biomass in a Brazilian semiarid region reservoir (Argemiro de Figueiredo reservoir). Sampling occurred between August 2007 and July 2009 on a bi-monthly basis for the first year, and in a monthly basis for the last two years. There were three collection points (PC: river confluence; PNC: near the cages; PD: dam site). The water environment analysis of abiotic variables included: temperature, transparency, coefficient of vertical light attenuation, dissolved oxygen, pH, electrical conductivity, alkalinity, dissolved inorganic nitrogen, and reactive soluble phosphorus. Phytoplankton samples were collected into a Van Dorn bottle, and were then preserved in acetic lugol and were quantified using an inverted microscope to determine phytoplankton density and biomass; the identified species were assembled in functional groups. The data were explored by canonical correspondence analysis. Individual analyses were made to test the temporal and spatial variability of the data and the factors that interfered most with the biotic and abiotic variables. Functional groups S1, SN, and K, consisting of filamentous Planktothrix agardhii (Gomont) Anagnostidis & Komárek, Cylindrospermopsis raciborskii (Woloszynska) Seenaya & Subba Raju, and the coccoid Aphanocapsa incerta (Lemmermann) Cronberg & Komárek, respectively, dominated the dry months when the water was warm, turbid, and alkaline. The overflow reservoir served as a natural disturbance reducing the phytoplankton biomass to less than 50 % and the dominance of cyanobacteria, promoting the domain of functional groups F, M, MP, Lo, and X2. The nutrient inputs from intensive fish farming, associated with a low local depth (Zmax = 7.7 m) close to the cages (PNC), resulted in a significant human disturbance that increased the prevalence of functional groups S1, SN, and K, which are composed primarily of cyanobacteria. We concluded that, in reservoirs, overflow events are natural disturbances that have the ability to reduce phytoplankton biomass and alter the structure of local communities, and that intensive fish farming is an anthropogenic disturbance that increases the availability of nutrients and stimulates an increase in biomass of the functional groups that include cyanobacteria. Furthermore, the functional groups of phytoplankton were reliable control of environmental conditions in the reservoirs of tropical semiarid regions.

Top-down and bottom-up interactions in freshwater ecosystems: emerging complexities

2015 ◽  
pp. 55-85 ◽  
Author(s):  
Jason M. Taylo ◽  
Michael J. Vanni ◽  
Alexander S. Flecker
Keyword(s):  
Freshwater Ecosystems ◽  
Top Down ◽  
Bottom Up

scholarly journals Study about Top-Down and Bottom-Up Controls in Regulating the Phytoplankton Biomass in a Eutrophic Reservoir in Northeastern Brazil

2012 ◽  
Vol 04 (08) ◽  
pp. 616-621 ◽  
Author(s):  
Juliana dos Santos Severiano ◽  
Ariadne do Nascimento Moura ◽  
Enaide Marinho de Melo Magalhães ◽  
Viviane Lúcia dos Santos Almeida
Keyword(s):  
Phytoplankton Biomass ◽  
Northeastern Brazil ◽  
Top Down ◽  
Bottom Up ◽  
Eutrophic Reservoir

scholarly journals Phytoplankton competition during the spring bloom in four Plankton Functional Type Models

2012 ◽  
Vol 9 (12) ◽  
pp. 18083-18129 ◽  
Author(s):  
T. Hashioka ◽  
M. Vogt ◽  
Y. Yamanaka ◽  
C. Le Quéré ◽  
E. T. Buitenhuis ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Spring Bloom ◽  
Marine Ecosystems ◽  
Grazing Pressure ◽  
Similar Degree ◽  
Functional Type ◽  
Top Down ◽  
Bottom Up ◽  
The North ◽  
The Difference

Abstract. We investigated the mechanisms of phytoplankton competition during the spring bloom, one of the most dramatic seasonal events in lower-trophic level ecosystems, in four state-of-the-art Plankton Functional Type (PFTs) models: PISCES, NEMURO, PlankTOM5 and CCSM-BEC. In particular, we investigated the relative importance of different ecophysiological processes on the determination of the community structure, focusing both on the bottom-up and the top-down controls. The models reasonably reproduced the observed global distribution and seasonal variation of phytoplankton biomass. The fraction of diatoms with respect to the total phytoplankton biomass increases with the magnitude of the spring bloom in all models. However, the governing mechanisms differ between models, despite the fact that current PFT models represent ecophysiological processes using the same types of parameterizations. The increasing trend in the percentage of diatoms with increasing bloom magnitude is mainly caused by a stronger nutrient dependence of photosynthesis for diatoms compared to nanophytoplankton (bottom-up control). The difference in the maximum photosynthesis rate plays an important role in NEMURO and PlankTOM5 and determines the absolute values of the percentage of diatoms during the bloom. In CCSM-BEC, the light dependency of photosynthesis plays an important role in the North Atlantic and the Southern Ocean. The grazing pressure by zooplankton (top-down control), however, strongly contributes to the dominance of diatoms in PISCES and CCSM-BEC. The regional differences in the percentage of diatoms in PlankTOM5 are mainly determined by top-down control. These differences in the mechanisms suggest that the response of marine ecosystems to climate change could significantly differ among models, even if the present-day ecosystem is reproduced to a similar degree of confidence. For further understanding of plankton competition and for the prediction of future change in marine ecosystems, it is important to understand the relative differences in each physiological rate and life history rate in the bottom-up and the top-down controls between PFTs.

Successful restoration of a tropical shallow eutrophic lake: Strong bottom-up but weak top-down effects recorded

2018 ◽  
Vol 146 ◽  
pp. 88-97 ◽  
Author(s):  
Zhengwen Liu ◽  
Jinrun Hu ◽  
Ping Zhong ◽  
Xiufeng Zhang ◽  
Jiajia Ning ◽  
...  
Keyword(s):  
Eutrophic Lake ◽  
Top Down ◽  
Bottom Up ◽  
Shallow Eutrophic Lake

scholarly journals Phytoplankton competition during the spring bloom in four plankton functional type models

2013 ◽  
Vol 10 (11) ◽  
pp. 6833-6850 ◽  
Author(s):  
T. Hashioka ◽  
M. Vogt ◽  
Y. Yamanaka ◽  
C. Le Quéré ◽  
E. T. Buitenhuis ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Spring Bloom ◽  
Maximum Growth ◽  
Marine Ecosystems ◽  
Grazing Pressure ◽  
Maximum Growth Rate ◽  
Similar Degree ◽  
Functional Type ◽  
Top Down ◽  
Bottom Up

Abstract. We investigated the mechanisms of phytoplankton competition during the spring bloom, one of the most dramatic seasonal events in lower-trophic-level ecosystems, in four state-of-the-art plankton functional type (PFT) models: PISCES, NEMURO, PlankTOM5 and CCSM-BEC. In particular, we investigated the relative importance of different ecophysiological processes on the determination of the community structure, focusing both on the bottom-up and the top-down controls. The models reasonably reproduced the observed global distribution and seasonal variation of phytoplankton biomass. The fraction of diatoms with respect to the total phytoplankton biomass increases with the magnitude of the spring bloom in all models. However, the governing mechanisms differ between models, despite the fact that current PFT models represent ecophysiological processes using the same types of parameterizations. The increasing trend in the percentage of diatoms with increasing bloom magnitude is mainly caused by a stronger nutrient dependence of diatom growth compared to nanophytoplankton (bottom-up control). The difference in the maximum growth rate plays an important role in NEMURO and PlankTOM5 and determines the absolute values of the percentage of diatoms during the bloom. In CCSM-BEC, the light dependency of growth plays an important role in the North Atlantic and the Southern Ocean. The grazing pressure by zooplankton (top-down control), however, strongly contributes to the dominance of diatoms in PISCES and CCSM-BEC. The regional differences in the percentage of diatoms in PlankTOM5 are mainly determined by top-down control. These differences in the mechanisms suggest that the response of marine ecosystems to climate change could significantly differ among models, even if the present-day ecosystem is reproduced to a similar degree of confidence. For further understanding of plankton competition and for the prediction of future change in marine ecosystems, it is important to understand the relative differences in each physiological rate and life history rate in the bottom-up and the top-down controls between PFTs.

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