scholarly journals Responses of phytoplankton functional groups to environmental factors in the Maixi River, southwest China

2017 ◽  
Author(s):  
Guojia Huang ◽  
Qiuhua Li ◽  
Xiaoqing Wang ◽  
Mengshu Han ◽  
Lei Li ◽  
...  
Keyword(s):  
Steady State ◽  
Phase I ◽  
Functional Groups ◽  
Phase Ii ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Early Summer ◽  
Late Spring ◽  
Total Biomass ◽  
Phytoplankton Functional Groups

<p>The functional groups approach is an efficient way to analyze seasonal changes in phytoplankton biomass as it is based on the physiological, morphological, and ecological attributes of the species. In this study, we identified the functional groups and driving factors behind short-term succession in phytoplankton communities. We analyzed physical, chemical, and biological factors of the Maixi River in Baihua Reservoir (BHR) from August to September, 2013 (summer, phase I) and March to May, 2014 (late spring and early summer, phase II). The 226 samples collected were divided into 23 functional groups. In phase I, phytoplankton biomass ranged from 4.88 to 30.59 mg·L<sup>-1</sup>, and the group S1 (<em>Pseudanabaena limnetica</em>) had the greatest biomass. In phase II, phytoplankton biomass ranged from 2.22 to 50.61 mg·L<sup>-1</sup>, and groups Y (<em>Cryptomonas</em> sp.) and S1 (<em>P. limnetica</em>) had the greatest biomass. Dominant functional groups in the Maixi River changed from S1 + D + Y + Lo in phase I to Y + S1 in summer. Changes in the phytoplankton community varied between 0 and 0.144 day<sup>-1 </sup>in phase I and between 0.008 and 0.389 day<sup>-1 </sup>in later spring and early summer. This showed a steady-state phytoplankton community during the two phases, in which the functional groups S1 (<em>P. limnetica</em>) and Y (<em>Cryptomonas</em> sp.) were dominant.<em> Pseudanabaena limnetica</em>, <em>Synedra </em>sp., <em>Peridinium </em>sp., and<em> Cryptomonas</em> sp. were dominant during summer, contributing to 70% of the total biomass in the steady-state community, and<em> P. limnetica</em>,<em> Synedra </em>sp., <em>Cryptomonas</em> sp.,<em> </em>and <em>Chlamydomonas</em> sp. were dominant during later spring and early summer, contributing to 60% of the total biomass in the community. Groups S1, D, and Y formed easily in the Maixi River, but <em>P. limnetica</em> was the dominant species in the eutrophic conditions of the Maixi River. According to biotic and abiotic factors, we concluded that the Maixi River is hypertrophic, and water resource management should take blooms of <em>P. limnetica</em> occurring in May into account. Temperature and dissolved oxygen were the critical factors affecting the steady-state of the phytoplankton community in late spring and early summer and summer, respectively. Because the Maixi River is an important source in the BHR, its phytoplankton functional groups directly affect the ecological balance of the water environment.</p>

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.

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 Pelagic community production and carbon-nutrient stoichiometry under variable ocean acidification in an Arctic fjord

2013 ◽  
Vol 10 (7) ◽  
pp. 4847-4859 ◽  
Author(s):  
A. Silyakova ◽  
R. G. J. Bellerby ◽  
K. G. Schulz ◽  
J. Czerny ◽  
T. Tanaka ◽  
...  
Keyword(s):  
Phase I ◽  
Ocean Acidification ◽  
Phase Ii ◽  
Inorganic Carbon ◽  
Phytoplankton Community ◽  
P Uptake ◽  
Phase Iii ◽  
Cumulative Change ◽  
Carbon Concentrations ◽  
Community Production

Abstract. Net community production (NCP) and carbon to nutrient uptake ratios were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, western Svalbard, during June–July 2010. Nutrient depleted fjord water with natural plankton assemblages, enclosed in nine mesocosms of ~ 50 m3 in volume, was exposed to pCO2 levels ranging initially from 185 to 1420 μatm. NCP estimations are the cumulative change in dissolved inorganic carbon concentrations after accounting for gas exchange and total alkalinity variations. Stoichiometric coupling between inorganic carbon and nutrient net uptake is shown as a ratio of NCP to a cumulative change in inorganic nutrients. Phytoplankton growth was stimulated by nutrient addition half way through the experiment and three distinct peaks in chlorophyll a concentration were observed during the experiment. Accordingly, the experiment was divided in three phases. Cumulative NCP was similar in all mesocosms over the duration of the experiment. However, in phases I and II, NCP was higher and in phase III lower at elevated pCO2. Due to relatively low inorganic nutrient concentration in phase I, C : N and C : P uptake ratios were calculated only for the period after nutrient addition (phase II and phase III). For the total post-nutrient period (phase II + phase III) ratios were close to Redfield, however they were lower in phase II and higher in phase III. Variability of NCP, C : N and C : P uptake ratios in different phases reflects the effect of increasing CO2 on phytoplankton community composition and succession. The phytoplankton community was composed predominantly of haptophytes in phase I, prasinophytes, dinoflagellates, and cryptophytes in phase II, and haptophytes, prasinophytes, dinoflagellates and chlorophytes in phase III (Schulz et al., 2013). Increasing ambient inorganic carbon concentrations have also been shown to promote primary production and carbon assimilation. For this study, it is clear that the pelagic ecosystem response to increasing CO2 is more complex than that represented in previous work, e.g. Bellerby et al. (2008). Carbon and nutrient uptake representation in models should, where possible, be more focused on individual plankton functional types as applying a single stoichiometry to a biogeochemical model with regard to the effect of increasing pCO2 may not always be optimal. The phase variability in NCP and stoichiometry may be better understood if CO2 sensitivities of the plankton's functional type biogeochemical uptake kinetics and trophic interactions are better constrained.

scholarly journals Spatial autocorrelation of phytoplankton biomass is weak in the rivers of Lake Taihu Basin, China

2019 ◽  
pp. 35
Author(s):  
Zhaoshi Wu ◽  
Ming Kong ◽  
Yamin Fan ◽  
Xiaolong Wang ◽  
Kuanyi Li
Keyword(s):  
Community Structure ◽  
Spatial Autocorrelation ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Lake Taihu ◽  
Total Biomass ◽  
Phytoplankton Community Structure ◽  
River Systems ◽  
Toxic Cyanobacteria ◽  
The Mean

We investigated the characteristic of phytoplankton community structure across the entire Lake Taihu Basin (LTB), one of the most developed areas in China. A morphologically based functional group (MBFG) proposed by Kruk et al. (2010), especially potential toxic cyanobacteria (group III and VII), was also illustrated. Samples were collected at 96 sites along main rivers throughout the four seasons from September 2014 to January 2016. Significant differences in the phytoplankton community structure were observed at spatial (particularly between Huangpu/Tiaoxi and the other 4 river systems) and seasonal scales. On a spatial basis, high variability was observed in the mean phytoplankton biomass, with a relatively high value of 3.13 mg L−1 in Yanjiang system and a relatively low value in Huangpu (1.23 mg L−1) and Tiaoxi (1.44 mg L−1) systems. The mean biomass of potential toxic cyanobacteria accounted for 18.28% of the mean total biomass spatially, which was more abundant in Nanhe and Yanjiang systems. Spatial autocorrelation was weak for the total biomass and its four main components (bacillariophyta, chlorophyta, euglenophyta, and cyanobacteria) at whole basin scale regardless of season. Regarding the river system, significant autocorrelation was scarcely observed in all the river systems except Huangpu, especially in the inflows. The characteristic in terms of hydrological and environmental conditions may determine the community structure of the 6 river systems. Our study highlighted the importance of monitoring based on a large spatial scale, and more attention should be paid to potential toxic cyanobacteria for water quality management purposes.

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.

A VARIABILIDADE AMBIENTAL INFLUENCIA A COMPOSIÇÃO E BIOMASSA FITOPLANCTÔNICA DE UM RESERVATÓRIO NEOTROPICAL

2021 ◽  
Vol 25 (01) ◽  
pp. 90-102
Author(s):  
Bárbara Marques dos Santos ◽  
◽  
Silvia Moreira dos Santos ◽  
Cláudia Alves de Souza ◽  
Carlos Roberto Alves dos Santos ◽  
...  
Keyword(s):  
Water Temperature ◽  
Phytoplankton Biomass ◽  
Phytoplankton Community ◽  
Environmental Variability ◽  
Total Biomass ◽  
Dry Period ◽  
Rainy Period ◽  
Biomass Structure ◽  
Health Relevance ◽  
Spatio Temporal

Phytoplankton is an important model of the aquatic environments functioning, responding directly to environmental variability in space and time. Therefore, represents an excellent tool for the monitoring of reservoirs, which comprise highly heterogeneous ecosystems longitudinally, influencing the structure and distribution of phytoplankton species. The objective of this study was to investigate the variation in the composition and biomass of the phytoplankton in a reservoir in the Goiás state, Brazil, and how these organisms respond to environmental variability along the reservoir spatial extent in dry and rainy periods. The phytoplankton and environmental variables were collected during one dry period and other rainy, over seven sampling sites, distributed in the regions downstream of the dam, lacustrine, intermediate and lotic of the reservoir. The composition and biomass of the phytoplankton community were measured as a response to the spatial and temporal environmental variability. We recorded a spatio-temporal variation in water temperature, light, nutrients, and phytoplankton biomass. Cyanobacteria had the highest biomass in the lacustrine and intermediate regions, while diatoms in the lotic region, in both periods. The highest phytoplankton total biomass was recorded in rainy period. We recorded a clear relation between the phytoplankton biomass and the environmental variability, being that water temperature, turbidity and soluble iron the ones that showed the biggest influence on the biomass structure. Thus, the composition and biomass of the phytoplankton community can be important metrics of reservoirs functioning and, therefore, the phytoplankton study in these ecosystems it's of interest in their monitoring, since reservoirs have great ecological, economic or public health relevance

scholarly journals Seston fatty acids to quantify phytoplankton functional groups and their spatiotemporal dynamics in a highly turbid estuary

2019 ◽  
Author(s):  
José-Pedro Cañavate ◽  
Stefanie van Bergeijk ◽  
Enrique González-Ortegón ◽  
César Vílas
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Functional Groups ◽  
Phytoplankton Community ◽  
River Flow ◽  
River Estuary ◽  
Community Research ◽  
Salinity Range ◽  
Phytoplankton Functional Groups ◽  
Taxonomic Groups

AbstractPhytoplankton community composition expresses estuarine functionality and its assessment can be improved by implementing novel quantitative fatty acid based procedures. Fatty acids have similar potential to pigments for quantifying phytoplankton functional groups but have been far less applied. A recently created dataset containing vast information on fatty acids of phytoplankton taxonomic groups was used as reference to quantify phytoplankton functional groups in the yet undescribed Guadalquivir River Estuary. Twelve phytoplankton groups were quantitatively distinguished by iterative matrix factor analysis of seston fatty acid signatures in this turbid estuary. Those phytoplankton groups including species unfeasible for microscopy identification (coccoid or microflagellated cells) could be quantified when using fatty acids. Conducting monthly matrix factor analyses over a period of two years and the full salinity range of the estuary indicated that diatoms dominated about half of the phytoplankton community spatiotemporally. The abundance of Cyanobacteria and Chlorophytes was inversely related to salinity and little affected by seasonality. Euglenophytes were also more abundant at lower salinity, increasing their presence in autumn-winter. Coccolithophores and Dinophytes contributed more to phytoplankton community at higher salinity and remained little affected by seasonality. Multivariate canonical analysis indicated that the structure of the estuarine phytoplankton community was most influenced by salinity, secondly influenced by water temperature, irradiance and river flow, and unaffected by nutrients. Fatty acids are especially suited for phytoplankton community research in high turbid estuaries and generate outcomes in synergy with those derived from classical pigment assessments.

Phase I/II Pharmacodynamic Study of the P-Glycoprotein (Pgp) Inhibitor Zosuquidar Administered by Continuous Infusion (CIV) with Daunorubicin (DNR) and Cytarabine (ARA-C) as Primary Therapy in Older Patients with Acute Myeloid Leukemia (AML).

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 422-422 ◽  
Author(s):  
Jeffrey Lancet ◽  
Maria R. Baer ◽  
Larry D. Cripe ◽  
Alan F. List ◽  
John F. Marcelletti ◽  
...  
Keyword(s):  
Steady State ◽  
Phase I ◽  
Phase Ii ◽  
Older Patients ◽  
Phase Ii Trial ◽  
Plasma Concentrations ◽  
Phase Iii ◽  
Functional Assay ◽  
Primary Therapy ◽  
Functional Inhibition

Abstract Pgp expression in AML increases with age and adversely affects treatment response and survival. Zosuquidar is a potent and highly specific Pgp inhibitor with minimal pharmacokinetic (PK) interaction with conventional xenobiotic antineoplastics. Previous studies established that plasma concentrations &gt; 170 ng/mL achieve complete functional inhibition of Pgp. Prolonged Pgp blockade is necessary to optimize antineoplastic sensitization in resistant cells in vitro, but was not applied previously. Specifically, the 72-hour CIV schedule of zosuquidar in this trial differs from the 6-hour infusion employed in the E3999 Phase III trial of this agent. We initiated a Phase I/II trial of zosuquidar as a 72-hr CIV in older patients with newly diagnosed AML. Objectives of the Phase I study were to establish safety and determine the dose necessary to achieve a sustained zosuquidar plasma level &gt; 170 ng/mL with in vivo validation of Pgp functional inhibition. Eligibility included ages 55–75, ECOG PS 0–2, adequate end-organ function, and Pgp activity by functional assay (Phase II only). Phase II objective is to determine the complete remission rate (CR) in Pgp+ patients. Planned zosuquidar dose levels of 700 mg/d and 800 mg/d were based upon PK modeling predicting achievement of plasma inhibitory concentrations [&gt; 170 ng/mL] in 93% and 97% of patients, respectively, within 4 hours. Zosuquidar was initiated 4 hrs prior to the first doses of DNR (45 mg/m2/d x 3d) and ARA-C (100 mg/m2/d CIV x 7d) and continued for 72 hrs. Patients who achieved a CR received up to 2 cycles of consolidation with the same agents using an abbreviated schedule. The Phase I portion of the trial has been completed with 16 patients: 10 patients received 700 mg/d of zosuquidar and 6 patients, 800 mg/d. The median age was 66; M/F was 9/7; cytogenetics: adverse (6), intermediate (7), favorable (1) and unknown (2); de novo/secondary AML: 8/8; Pgp+ by functional assay (11). Phase I DLTs included one death due to respiratory failure on Day 8 of induction (700 mg/d); one patient with delayed bone marrow recovery and one patient with Grade 3 reversible delirium (800 mg/d). Early death (&lt; 30 days) occurred in 1 patient. Other adverse events attributed to zosuquidar include reversible tremor (48%), dizziness (15%) and confusion (11%). Mean zosuquidar steady-state concentrations were 220±57 ng/mL (700 mg/d) and 462±222 ng/mL (800 mg/d), with a median of 49–52 hours above 170 ng/mL. Pharmacodynamic studies using circulating NK cells as an index of Pgp activity showed near complete inhibition (&gt;90%) by 4 hours that was sustained throughout the infusion in all patients tested. Based upon these data, the recommended Phase II dose of zosuquidar by 72-hr CIV is 700 mg/d. An additional 9 Pgp+ patients have been enrolled to the Phase II trial. Among the total 20 evaluable Pgp+ patients, 10 (50%) have achieved CR or CRp. Zosuquidar 700 mg/d administered by CIV with DNR/ARA-C is well tolerated and achieves rapid and sustained Pgp inhibition at steady state plasma levels, with preliminary evidence of clinical benefit in Pgp+ patients. Accrual to the Phase II trial is ongoing.

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