Environmental Science › Environmental Chemistry

Aquatic Ecosystems and Phytoplankton Dynamics

Works Count: 76829

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Description

This cluster of papers focuses on the phenomenon of eutrophication in freshwater and coastal marine ecosystems, particularly its role in promoting harmful algal blooms dominated by cyanobacteria. The papers discuss the links between eutrophication, climate change, nutrient control, and the management of lakes and reservoirs to mitigate the impacts of harmful algal blooms. Additionally, they explore the ecological and health implications of toxins produced by cyanobacteria in the context of eutrophication.

Keywords

Eutrophication; Harmful Algal Blooms; Cyanobacteria; Nutrient Control; Climate Change; Freshwater Ecosystems; Toxins; Phosphorus; Lake Management; Water Quality

Controlling Eutrophication: Nitrogen and Phosphorus

2009-02-19

Daniel J. Conley , Hans W. Paerl , Robert W. Howarth +5 more

Variations of sediment organic phosphorus and organic carbon during the outbreak and decline of algal blooms in Lake Taihu, China, Variations of sediment organic phosphorus and organic carbon during the outbreak and decline of algal blooms in Lake Taihu, China,

Toxic cyanobacteria in water. A guide to their public health consequences, monitoring, and management

2000-07-01

Kirsten Christoffersen , Hanne Kaas

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Toxic Cyanobacteria in Water

1999-02-11

Ingrid Chorus , Jamie Bartram

Cyanobacteria and their toxins are an increasing global public health menace. Most recently, problems have been experienced in Australia, the United States and, due to drought and increasing water scarcity, … Cyanobacteria and their toxins are an increasing global public health menace. Most recently, problems have been experienced in Australia, the United States and, due to drought and increasing water scarcity, pose a severe threat in the U.K. With an international range of contributors, all leading experts in their fields, Toxic Cyanobacteria in Water examines the increasing need to protect drinking water and water resources from the hazards of Cyanobacteria and their impact on health. Written and edited by a World Health Organization working group, Toxic Cyanobacteria in Water is an operational handbook in a practical, assessible style.Toxic Cyanobacteria in Water will be invaluable to environmental health officers, professionals in the fields of water supply, public health, fresh water ecology and education, national and international organizations, special interest groups, post-graduate students and utilities responsible for managing drinking water supplies.

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The phosphorus‐chlorophyll relationship in lakes1,2

1974-09-01

Peter J. Dillon , F. H. Rigler

Data for summer chlorophyll and spring total phosphorus concentration were collected from 19 lakes in southern Ontario and combined with data reported in the literature for other North American lakes … Data for summer chlorophyll and spring total phosphorus concentration were collected from 19 lakes in southern Ontario and combined with data reported in the literature for other North American lakes to produce a regression line that can be used to predict the average summer chlorophyll concentration from a single measurement of phosphorus concentration at spring overturn. This equation is not significantly different from a previously published phosphorus‐chlorophyll relationship derived for a number of Japanese lakes.

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Alternative equilibria in shallow lakes

1993-08-01

Marten Scheffer , S. H. Hosper , Marie-Louise Meijer +2 more

Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment

2008-07-31

David W. Schindler , Robert E. Hecky , D. L. Findlay +6 more

Lake 227, a small lake in the Precambrian Shield at the Experimental Lakes Area (ELA), has been fertilized for 37 years with constant annual inputs of phosphorus and decreasing inputs … Lake 227, a small lake in the Precambrian Shield at the Experimental Lakes Area (ELA), has been fertilized for 37 years with constant annual inputs of phosphorus and decreasing inputs of nitrogen to test the theory that controlling nitrogen inputs can control eutrophication. For the final 16 years (1990–2005), the lake was fertilized with phosphorus alone. Reducing nitrogen inputs increasingly favored nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation. Nitrogen fixation was sufficient to allow biomass to continue to be produced in proportion to phosphorus, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally. To reduce eutrophication, the focus of management must be on decreasing inputs of phosphorus.

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Record-setting algal bloom in Lake Erie caused by agricultural and meteorological trends consistent with expected future conditions

2013-04-01

A. M. Michalak , Eric J. Anderson , Dmitry Beletsky +7 more

In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show … In 2011, Lake Erie experienced the largest harmful algal bloom in its recorded history, with a peak intensity over three times greater than any previously observed bloom. Here we show that long-term trends in agricultural practices are consistent with increasing phosphorus loading to the western basin of the lake, and that these trends, coupled with meteorological conditions in spring 2011, produced record-breaking nutrient loads. An extended period of weak lake circulation then led to abnormally long residence times that incubated the bloom, and warm and quiescent conditions after bloom onset allowed algae to remain near the top of the water column and prevented flushing of nutrients from the system. We further find that all of these factors are consistent with expected future conditions. If a scientifically guided management plan to mitigate these impacts is not implemented, we can therefore expect this bloom to be a harbinger of future blooms in Lake Erie.

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Liver Failure and Death after Exposure to Microcystins at a Hemodialysis Center in Brazil

1998-03-26

Elise M. Jochimsen , Wayne W. Carmichael , Jisi An +7 more

Hemodialysis is a common but potentially hazardous procedure. From February 17 to 20, 1996, 116 of 130 patients (89 percent) at a dialysis center (dialysis center A) in Caruaru, Brazil, … Hemodialysis is a common but potentially hazardous procedure. From February 17 to 20, 1996, 116 of 130 patients (89 percent) at a dialysis center (dialysis center A) in Caruaru, Brazil, had visual disturbances, nausea, and vomiting associated with hemodialysis. By March 24, 26 of the patients had died of acute liver failure.

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Cyanobacterial toxins: risk management for health protection

2004-07-30

Geoffrey A. Codd , Louise F. Morrison , James S. Metcalf

Cyanobacteria secondary metabolites—the cyanotoxins

1992-06-01

Wayne W. Carmichael

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Resource Competition between Plankton Algae: An Experimental and Theoretical Approach

1977-03-01

David Tilman

The results of 76 long—term competition experiments between two species of freshwater algae (Asterionella formosa and Cyclotella meneghiniana) grown along a resource gradient agree with the predictions of two different … The results of 76 long—term competition experiments between two species of freshwater algae (Asterionella formosa and Cyclotella meneghiniana) grown along a resource gradient agree with the predictions of two different models of resource competition. Both models are based on the functional resource—utilization response of each species to limiting resources. The Monod and the Variable Internal Stores model of competition made similar predictions. Asterionella was observed to be competitively dominant when both species were phosphate limited; Cyclotella was dominant when both species were silicate limited; and both species stably coexisted when each species was growth—rate limited by a different resource. Almost 75% of the variance in the relative abundances of these two species along a natural silicate—phosphate gradient in Lake Michigan is explained by the Monod model.

Trophic Relationships in Freshwater Pelagic Ecosystems

1986-08-01

Donald J. McQueen , John R. Post , Edward L. Mills

Relative impacts of bottom-up (producer controlled) and top-down (consumer controlled) forces on the biomass and size structure of five major components of freshwater pelagic systems (piscivores, planktivores, zooplankton, phytoplankton, and … Relative impacts of bottom-up (producer controlled) and top-down (consumer controlled) forces on the biomass and size structure of five major components of freshwater pelagic systems (piscivores, planktivores, zooplankton, phytoplankton, and total phosphorus availability) were estimated. Predictions that emerge are (1) maximum biomass at each trophic level is controlled from below (bottom-up) by nutrient availability, (2) this bottom-up regulation is strongest at the bottom of the food web (i.e. phosphorus → phytoplankton) and weakens by a factor of 2 with each succeeding step up the food web, (3) as energy moves up a food web, the predictability of bottom-up interactions decreases, (4) near the top of the food web, top-down (predator mediated) interactions are strong and have low coefficients of variation, but weaken with every step down the food web, (5) variability around the bottom-up regressions can always be explained by top-down forces, and (6) interplay between top-down and bottom-up effects changes with the trophic status of lakes. In eutrophic lakes, top-down effects are strong for piscivore → zooplankton, weaker for planktivore → zooplankton, and have little impact for zooplankton → phytoplankton. For oligotrophic lakes, the model predicts that top-down effects are not strongly buffered, so that zooplankton → phytoplankton interactions are significant.

Lake responses to reduced nutrient loading – an analysis of contemporary long‐term data from 35 case studies

2005-08-26

Erik Jeppesen , Martin Søndergaard , Jens Peder Jensen +7 more

Summary 1. This synthesis examines 35 long‐term (5–35 years, mean: 16 years) lake re‐oligotrophication studies. It covers lakes ranging from shallow (mean depth <5 m and/or polymictic) to deep (mean … Summary 1. This synthesis examines 35 long‐term (5–35 years, mean: 16 years) lake re‐oligotrophication studies. It covers lakes ranging from shallow (mean depth <5 m and/or polymictic) to deep (mean depth up to 177 m), oligotrophic to hypertrophic (summer mean total phosphorus concentration from 7.5 to 3500 μ g L −1 before loading reduction), subtropical to temperate (latitude: 28–65°), and lowland to upland (altitude: 0–481 m). Shallow north‐temperate lakes were most abundant. 2. Reduction of external total phosphorus (TP) loading resulted in lower in‐lake TP concentration, lower chlorophyll a (chl a ) concentration and higher Secchi depth in most lakes. Internal loading delayed the recovery, but in most lakes a new equilibrium for TP was reached after 10–15 years, which was only marginally influenced by the hydraulic retention time of the lakes. With decreasing TP concentration, the concentration of soluble reactive phosphorus (SRP) also declined substantially. 3. Decreases (if any) in total nitrogen (TN) loading were lower than for TP in most lakes. As a result, the TN : TP ratio in lake water increased in 80% of the lakes. In lakes where the TN loading was reduced, the annual mean in‐lake TN concentration responded rapidly. Concentrations largely followed predictions derived from an empirical model developed earlier for Danish lakes, which includes external TN loading, hydraulic retention time and mean depth as explanatory variables. 4. Phytoplankton clearly responded to reduced nutrient loading, mainly reflecting declining TP concentrations. Declines in phytoplankton biomass were accompanied by shifts in community structure. In deep lakes, chrysophytes and dinophytes assumed greater importance at the expense of cyanobacteria. Diatoms, cryptophytes and chrysophytes became more dominant in shallow lakes, while no significant change was seen for cyanobacteria. 5. The observed declines in phytoplankton biomass and chl a may have been further augmented by enhanced zooplankton grazing, as indicated by increases in the zooplankton : phytoplankton biomass ratio and declines in the chl a : TP ratio at a summer mean TP concentration of <100–150 μ g L −1 . This effect was strongest in shallow lakes. This implies potentially higher rates of zooplankton grazing and may be ascribed to the observed large changes in fish community structure and biomass with decreasing TP contribution. In 82% of the lakes for which data on fish are available, fish biomass declined with TP. The percentage of piscivores increased in 80% of those lakes and often a shift occurred towards dominance by fish species characteristic of less eutrophic waters. 6. Data on macrophytes were available only for a small subsample of lakes. In several of those lakes, abundance, coverage, plant volume inhabited or depth distribution of submerged macrophytes increased during oligotrophication, but in others no changes were observed despite greater water clarity. 7. Recovery of lakes after nutrient loading reduction may be confounded by concomitant environmental changes such as global warming. However, effects of global change are likely to run counter to reductions in nutrient loading rather than reinforcing re‐oligotrophication.

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Eutrophication of freshwater and coastal marine ecosystems a global problem

2003-03-01

Val H. Smith

Controlling harmful cyanobacterial blooms in a world experiencing anthropogenic and climatic-induced change

2011-02-24

Hans W. Paerl , Nathan S. Hall , Elizabeth S. Calandrino

The dry weight estimate of biomass in a selection of Cladocera, Copepoda and Rotifera from the plankton, periphyton and benthos of continental waters

1975-03-01

Henri J. Dumont , Isabella Van de Velde , Simonne Dumont

Effects of submersed macrophytes on ecosystem processes

1986-01-01

Stephen R. Carpenter , David M. Lodge

Both natural and managed ecosystems experience large fluctuations in submersed macrophyte biomass. These fluctuations have important consequences for ecosystem processes because of the effects of macrophytes on the physical/chemical environment … Both natural and managed ecosystems experience large fluctuations in submersed macrophyte biomass. These fluctuations have important consequences for ecosystem processes because of the effects of macrophytes on the physical/chemical environment and littoral biota. The first part of this paper reviews the effects of submersed macrophytes on the physical environment (light extinction, temperature, hydrodynamics, substrate), chemical environment (oxygen, inorganic and organic carbon, nutrients) and the biota (epiphytes, grazers, detritivores, fishes). This extensive literature suggests that variations in macrophyte biomass could have major effects on aquatic ecosystems. The second part of this paper considers the ecosystem consequence of several common changes in submersed macrophytes: replacement of vascular macrophytes by bryophytes during lake acidification; short-term biomass changes caused by invasions of adventive species, cultural eutrophication or macrophyte management; and changes in littoral grazers. These scenarios illustrate the importance of macrophytes in ecosystems, but raise any questions which cannot be answered at present. Controlled, whole-lake macrophyte experiments are needed to resolve these open questions.

Cascading Trophic Interactions and Lake Productivity

1985-11-01

Stephen R. Carpenter , James F. Kitchell , James R. Hodgson

Journal Article Cascading Trophic Interactions and Lake Productivity: Fish predation and herbivory can regulate lake ecosystems Get access Stephen R. Carpenter, Stephen R. Carpenter Search for other works by this … Journal Article Cascading Trophic Interactions and Lake Productivity: Fish predation and herbivory can regulate lake ecosystems Get access Stephen R. Carpenter, Stephen R. Carpenter Search for other works by this author on: Oxford Academic Google Scholar James F. Kitchell, James F. Kitchell Search for other works by this author on: Oxford Academic Google Scholar James R. Hodgson James R. Hodgson Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 35, Issue 10, November 1985, Pages 634–639, https://doi.org/10.2307/1309989 Published: 01 November 1985

Low Nitrogen to Phosphorus Ratios Favor Dominance by Blue-Green Algae in Lake Phytoplankton

1983-08-12

Val H. Smith

An analysis of growing season data from 17 lakes throughout the world suggests that the relative proportion of blue-green algae (Cyanophyta) in the epilimnetic phytoplankton is dependent on the epilimnetic … An analysis of growing season data from 17 lakes throughout the world suggests that the relative proportion of blue-green algae (Cyanophyta) in the epilimnetic phytoplankton is dependent on the epilimnetic ratio of total nitrogen to total phosphorus. Blue-green algae tended to be rare when this ratio exceeded 29 to 1 by weight, suggesting that modification of this ratio by control of nutrient additions may provide a means by which lake water quality can be managed.

Harmful Cyanobacterial Blooms: Causes, Consequences, and Controls

2013-01-12

Hans W. Paerl , Timothy G. Otten

Generic Assignments, Strain Histories and Properties of Pure Cultures of Cyanobacteria

1979-03-01

Rosmarie Rippka , Roger Y. Stanier , Josette Deruelles +2 more

Summary: On the basis of a comparative study of 178 strains of cyanobacteria, representative of this group of prokaryotes, revised definitions of many genera are proposed. Revisions are designed to … Summary: On the basis of a comparative study of 178 strains of cyanobacteria, representative of this group of prokaryotes, revised definitions of many genera are proposed. Revisions are designed to permit the generic identification of cultures, often difficult through use of the field-based system of phycological classification. The differential characters proposed are both constant and readily determinable in cultured material. The 22 genera recognized are placed in five sections, each distinguished by a particular pattern of structure and development. Generic descriptions are accompanied by strain histories, brief accounts of strain properties, and illustrations; one or more reference strains are proposed for each genus. The collection on which this analysis was based has been deposited in the American Type Culture Collection, where strains will be listed under the generic designations proposed here.

Evolution of Phosphorus Limitation in Lakes

1977-01-21

D. W. Schindler

Towards a functional classification of the freshwater phytoplankton

2002-05-01

C. S. Reynolds , Vera L. M. Huszar , Carla Kruk +2 more

This paper considers the structure of freshwater phytoplankton assemblages and promotes a scheme of ‘vegetation recognition', based upon the functional associations of species represented in the plankton. These groups are … This paper considers the structure of freshwater phytoplankton assemblages and promotes a scheme of ‘vegetation recognition', based upon the functional associations of species represented in the plankton. These groups are often polyphyletic, recognizing commonly shared adaptive features, rather than common phylogeny, to be the key ecological driver. Thirty-one such associations are outlined and the basic pattern of their distinctive ecologies is outlined. An invitation to other plankton scientists to assist in the development of this scheme is issued.

An n-alkane proxy for the sedimentary input of submerged/floating freshwater aquatic macrophytes

2000-07-01

Katherine J. Ficken , B Li , David L. Swain +1 more

An improved method for the colorimetric determination of phosphate

1938-02-01

I. Berenblum , E. B. Chain

Research Article| February 01 1938 An improved method for the colorimetric determination of phosphate Isaac Berenblum; Isaac Berenblum 1The Sir William Dunn School of Pathology, Oxford Search for other works … Research Article| February 01 1938 An improved method for the colorimetric determination of phosphate Isaac Berenblum; Isaac Berenblum 1The Sir William Dunn School of Pathology, Oxford Search for other works by this author on: This Site PubMed Google Scholar Ernst Chain Ernst Chain 1The Sir William Dunn School of Pathology, Oxford Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1938) 32 (2): 295–298. https://doi.org/10.1042/bj0320295 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share MailTo Twitter LinkedIn Cite Icon Cite Get Permissions Citation Isaac Berenblum, Ernst Chain; An improved method for the colorimetric determination of phosphate. Biochem J 1 February 1938; 32 (2): 295–298. doi: https://doi.org/10.1042/bj0320295 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1938 CAMBRIDGE UNIVERSITY PRESS1938 Article PDF first page preview Close Modal You do not currently have access to this content.

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Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems: Evolving views over three decades

2006-01-01

Robert W. Howarth , Roxanne Marino

The first special volume of Limnology and Oceanography, published in 1972, focused on whether phosphorus (P) or carbon (C) is the major agent causing eutrophication in aquatic ecosystems. Only slight … The first special volume of Limnology and Oceanography, published in 1972, focused on whether phosphorus (P) or carbon (C) is the major agent causing eutrophication in aquatic ecosystems. Only slight mention was made that estuaries may behave differently from lakes and that nitrogen (N) may cause eutrophication in estuaries. In the following decade, an understanding of eutrophication in estuaries proceeded in relative isolation from the community of scientists studying lakes. National water quality policy in the United States was directed almost solely toward P control for both lakes and estuaries, and similarly, European nations tended to focus on P control in lakes. Although bioassay data indicated N control of eutrophication in estuaries as early as the 1970s, this body of knowledge was treated with skepticism by many freshwater scientists and water‐quality managers, because bioassay data in lakes often did not properly indicate the importance of P relative to C in those ecosystems. Hence, the bioassay data in estuaries had little influence on water‐quality management. Over the past two decades, a strong consensus has evolved among the scientific community that N is the primary cause of eutrophication in many coastal ecosystems. The development of this consensus was based in part on data from whole‐ecosystem studies and on a growing body of evidence that presented convincing mechanistic reasons why the controls of eutrophication in lakes and coastal marine ecosystems may differ. Even though N is probably the major cause of eutrophication in most coastal systems in the temperate zone, optimal management of coastal eutrophication suggests controlling both N and P, in part because P can limit primary production in some systems. In addition, excess P in estuaries can interact with the availability of N and silica (Si) to adversely affect ecological structure. Reduction of P to upstream freshwater ecosystems can also benefit coastal marine ecosystems through mechanisms such as increased Si fluxes.

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Blooms Like It Hot

2008-04-03

Hans W. Paerl , Jef Huisman

A link exists between global warming and the worldwide proliferation of harmful cyanobacterial blooms. A link exists between global warming and the worldwide proliferation of harmful cyanobacterial blooms.

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The Structuring Role of Submerged Macrophytes in Lakes

1998-01-01

Erik Jeppesen

The colorimetric determination of phosphorus

1932-01-01

E. J. King

Research Article| January 01 1932 The colorimetric determination of phosphorus Earl Judson King Earl Judson King 1Department of Medical Research, Banting Institute, University of Toronto Search for other works by … Research Article| January 01 1932 The colorimetric determination of phosphorus Earl Judson King Earl Judson King 1Department of Medical Research, Banting Institute, University of Toronto Search for other works by this author on: This Site PubMed Google Scholar Author and article information Publisher: Portland Press Ltd © 1932 CAMBRIDGE UNIVERSITY PRESS1932 Biochem J (1932) 26 (2): 292–297. https://doi.org/10.1042/bj0260292 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn Email Cite Icon Cite Get Permissions Citation Earl Judson King; The colorimetric determination of phosphorus. Biochem J 1 January 1932; 26 (2): 292–297. doi: https://doi.org/10.1042/bj0260292 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1932 CAMBRIDGE UNIVERSITY PRESS1932 Article PDF first page preview Close Modal You do not currently have access to this content.

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Climate change: a catalyst for global expansion of harmful cyanobacterial blooms

2009-02-01

Hans W. Paerl , Jef Huisman

Summary Cyanobacteria are the Earth's oldest known oxygen‐evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria … Summary Cyanobacteria are the Earth's oldest known oxygen‐evolving photosynthetic microorganisms, and they have had major impacts on shaping our current atmosphere and biosphere. Their long evolutionary history has enabled cyanobacteria to develop survival strategies and persist as important primary producers during numerous geochemical and climatic changes that have taken place on Earth during the past 3.5 billion years. Today, some cyanobacterial species form massive surface growths or ‘blooms’ that produce toxins, cause oxygen depletion and alter food webs, posing a major threat to drinking and irrigation water supplies, fishing and recreational use of surface waters worldwide. These harmful cyanobacteria can take advantage of anthropogenically induced nutrient over‐enrichment (eutrophication), and hydrologic modifications (water withdrawal, reservoir construction). Here, we review recent studies revealing that regional and global climatic change may benefit various species of harmful cyanobacteria by increasing their growth rates, dominance, persistence, geographic distributions and activity. Future climatic change scenarios predict rising temperatures, enhanced vertical stratification of aquatic ecosystems, and alterations in seasonal and interannual weather patterns (including droughts, storms, floods); these changes all favour harmful cyanobacterial blooms in eutrophic waters. Therefore, current mitigation and water management strategies, which are largely based on nutrient input and hydrologic controls, must also accommodate the environmental effects of global warming.

Nutrient limitation of phytoplankton in freshwater and marine environments: A review of recent evidence on the effects of enrichment1

1988-07-01

Robert E. Hecky , Peter Kilham

Phytoplankton can become limited by the availability of nutrients when light and temperature are adequate and loss rates are not excessive. The current paradigms for nutrient limitations in freshwater, estuarine, … Phytoplankton can become limited by the availability of nutrients when light and temperature are adequate and loss rates are not excessive. The current paradigms for nutrient limitations in freshwater, estuarine, and marine environments are quite different. A review of the experimental and observational data used to infer P or N limitation of phytoplankton growth indicates that P limitation in freshwater environments can be demonstrated rigorously at several hierarchical levels of system complexity, from algal cultures to whole lakes. A similarly rigorous demonstration of N limitation has not been achieved for marine waters. Therefore, we conclude that the extent and severity of N limitation in the marine environment remain an open question. Culture studies have established that internal cellular concentrations of nutrients determine phytoplankton growth rates, and these studies have shown that it is often difficult to relate growth rates to external concentrations, especially in natural situations. This should lead to a greater reliance on the composition of particulate matter and biomass‐based physiological rates to infer nutrient limitation. Such measurements have demonstrated their utility in a wide variety of freshwater and marine environments, and, most importantly, they can be applied to systems that are difficult to manipulate experimentally or budget accurately. Dissolved nutrient concentrations are most useful in determining nutrient loading rates of aquatic ecosystems. The relative proportions of nutrients supplied to phytoplankton can be a strong selective force shaping phytoplankton communities and affecting the biomass yield per unit of limiting nutrient.

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NONPOINT POLLUTION OF SURFACE WATERS WITH PHOSPHORUS AND NITROGEN

1998-08-01

Stephen R. Carpenter , N. F. Caraco , David L. Correll +3 more

Agriculture and urban activities are major sources of phosphorus and nitrogen to aquatic ecosystems. Atmospheric deposition further contributes as a source of N. These nonpoint inputs of nutrients are difficult … Agriculture and urban activities are major sources of phosphorus and nitrogen to aquatic ecosystems. Atmospheric deposition further contributes as a source of N. These nonpoint inputs of nutrients are difficult to measure and regulate because they derive from activities dispersed over wide areas of land and are variable in time due to effects of weather. In aquatic ecosystems, these nutrients cause diverse problems such as toxic algal blooms, loss of oxygen, fish kills, loss of biodiversity (including species important for commerce and recreation), loss of aquatic plant beds and coral reefs, and other problems. Nutrient enrichment seriously degrades aquatic ecosystems and impairs the use of water for drinking, industry, agriculture, recreation, and other purposes. Based on our review of the scientific literature, we are certain that (1) eutrophication is a widespread problem in rivers, lakes, estuaries, and coastal oceans, caused by overenrichment with P and N; (2) nonpoint pollution, a major source of P and N to surface waters of the United States, results primarily from agriculture and urban activity, including industry; (3) inputs of P and N to agriculture in the form of fertilizers exceed outputs in produce in the United States and many other nations; (4) nutrient flows to aquatic ecosystems are directly related to animal stocking densities, and under high livestock densities, manure production exceeds the needs of crops to which the manure is applied; (5) excess fertilization and manure production cause a P surplus to accumulate in soil, some of which is transported to aquatic ecosystems; and (6) excess fertilization and manure production on agricultural lands create surplus N, which is mobile in many soils and often leaches to downstream aquatic ecosystems, and which can also volatilize to the atmosphere, redepositing elsewhere and eventually reaching aquatic ecosystems. If current practices continue, nonpoint pollution of surface waters is virtually certain to increase in the future. Such an outcome is not inevitable, however, because a number of technologies, land use practices, and conservation measures are capable of decreasing the flow of nonpoint P and N into surface waters. From our review of the available scientific information, we are confident that: (1) nonpoint pollution of surface waters with P and N could be reduced by reducing surplus nutrient flows in agricultural systems and processes, reducing agricultural and urban runoff by diverse methods, and reducing N emissions from fossil fuel burning; and (2) eutrophication can be reversed by decreasing input rates of P and N to aquatic ecosystems, but rates of recovery are highly variable among water bodies. Often, the eutrophic state is persistent, and recovery is slow.

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Climate change: Links to global expansion of harmful cyanobacteria

2011-08-19

Hans W. Paerl , Valerie J. Paul

Summer heatwaves promote blooms of harmful cyanobacteria

2007-11-27

Klaus Jöhnk , Jef Huisman , Jonathan Sharples +3 more

Abstract Dense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. … Abstract Dense surface blooms of toxic cyanobacteria in eutrophic lakes may lead to mass mortalities of fish and birds, and provide a serious health threat for cattle, pets, and humans. It has been argued that global warming may increase the incidence of harmful algal blooms. Here, we report on a lake experiment where intermittent artificial mixing failed to control blooms of the harmful cyanobacterium Microcystis during the summer of 2003, one of the hottest summers ever recorded in Europe. To understand this failure, we develop a coupled biological–physical model investigating how competition for light between buoyant cyanobacteria, diatoms, and green algae in eutrophic lakes is affected by the meteorological conditions of this extreme summer heatwave. The model consists of a phytoplankton competition model coupled to a one‐dimensional hydrodynamic model, driven by meteorological data. The model predicts that high temperatures favour cyanobacteria directly, through increased growth rates. Moreover, high temperatures also increase the stability of the water column, thereby reducing vertical turbulent mixing, which shifts the competitive balance in favour of buoyant cyanobacteria. Through these direct and indirect temperature effects, in combination with reduced wind speed and reduced cloudiness, summer heatwaves boost the development of harmful cyanobacterial blooms. These findings warn that climate change is likely to yield an increased threat of harmful cyanobacteria in eutrophic freshwater ecosystems.

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Recent advances in the understanding and management of eutrophication

2006-01-01

D. W. Schindler

Major advances in the scientific understanding and management of eutrophication have been made since the late 1960s. The control of point sources of phosphorus reduced algal blooms in many lakes. … Major advances in the scientific understanding and management of eutrophication have been made since the late 1960s. The control of point sources of phosphorus reduced algal blooms in many lakes. Diffuse nutrient sources from land use changes and urbanization in the catchments of lakes have proved possible to control but require many years of restoration efforts. The importance of water residence time to eutrophication has been recognized. Changes in aquatic communities contribute to eutrophication via the trophic cascade, nutrient stoichiometry, and transport of nutrients from benthic to pelagic regions. Overexploitation of piscivorous fishes appears to be a particularly common amplifier of eutrophication. Internal nutrient loading can be controlled by reducing external loading, although the full response of lakes may take decades. In the years ahead, climate warming will aggravate eutrophication in lakes receiving point sources of nutrients, as a result of increasing water residence times. Decreased silica supplies from dwindling inflows may increasingly favor the replacement of diatoms by nitrogen‐fixing Cyanobacteria. Increases in transport of nitrogen by rivers to estuaries and coastal oceans have followed increased use of nitrogen in agriculture and increasing emissions to the atmosphere. Our understanding of eutrophication and its management has evolved from simple control of nutrient sources to recognition that it is often a cumulative effects problem that will require protection and restoration of many features of a lake's community and its catchment.

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Lakes as sentinels of climate change

2009-11-01

Rita Adrian , Catherine M. O’Reilly , Horacio E. Zagarese +7 more

While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a … While there is a general sense that lakes can act as sentinels of climate change, their efficacy has not been thoroughly analyzed. We identified the key response variables within a lake that act as indicators of the effects of climate change on both the lake and the catchment. These variables reflect a wide range of physical, chemical, and biological responses to climate. However, the efficacy of the different indicators is affected by regional response to climate change, characteristics of the catchment, and lake mixing regimes. Thus, particular indicators or combinations of indicators are more effective for different lake types and geographic regions. The extraction of climate signals can be further complicated by the influence of other environmental changes, such as eutrophication or acidification, and the equivalent reverse phenomena, in addition to other land‐use influences. In many cases, however, confounding factors can be addressed through analytical tools such as detrending or filtering. Lakes are effective sentinels for climate change because they are sensitive to climate, respond rapidly to change, and integrate information about changes in the catchment.

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Scientific fundamentals of the eutrophication of lakes and flowing waters, with particular reference to nitrogen and phosphorus as factors in eutrophication

1971-01-01

Richard A. Vollenweider

Role of sediment and internal loading of phosphorus in shallow lakes

2003-01-01

Martin Søndergaard , Jens Peder Jensen , Erik Jeppesen

Global ecological impacts of invasive species in aquatic ecosystems

2015-07-24

Belinda Gallardo , Miguel Clavero , Marta I. Sánchez +1 more

Abstract The introduction of invasive species, which often differ functionally from the components of the recipient community, generates ecological impacts that propagate along the food web. This review aims to … Abstract The introduction of invasive species, which often differ functionally from the components of the recipient community, generates ecological impacts that propagate along the food web. This review aims to determine how consistent the impacts of aquatic invasions are across taxa and habitats. To that end, we present a global meta‐analysis from 151 publications (733 cases), covering a wide range of invaders (primary producers, filter collectors, omnivores and predators), resident aquatic community components (macrophytes, phytoplankton, zooplankton, benthic invertebrates and fish) and habitats (rivers, lakes and estuaries). Our synthesis suggests a strong negative influence of invasive species on the abundance of aquatic communities, particularly macrophytes, zooplankton and fish. In contrast, there was no general evidence for a decrease in species diversity in invaded habitats, suggesting a time lag between rapid abundance changes and local extinctions. Invaded habitats showed increased water turbidity, nitrogen and organic matter concentration, which are related to the capacity of invaders to transform habitats and increase eutrophication. The expansion of invasive macrophytes caused the largest decrease in fish abundance, the filtering activity of filter collectors depleted planktonic communities, omnivores (including both facultative and obligate herbivores) were responsible for the greatest decline in macrophyte abundance, and benthic invertebrates were most negatively affected by the introduction of new predators. These impacts were relatively consistent across habitats and experimental approaches. Based on our results, we propose a framework of positive and negative links between invasive species at four trophic positions and the five different components of recipient communities. This framework incorporates both direct biotic interactions (predation, competition, grazing) and indirect changes to the water physicochemical conditions mediated by invaders (habitat alteration). Considering the strong trophic links that characterize aquatic ecosystems, this framework is relevant to anticipate the far‐reaching consequences of biological invasions on the structure and functionality of aquatic ecosystems.

Phytoplankton Community Ecology: The Role of Limiting Nutrients

1982-11-01

David Tilman , S. S. Kilham , Peter Kilham

Species distribution models (SDMs) are numerical tools that combine observations of species occurrence or abundance with environmental estimates. They are used to gain ecological and evolutionary insights and to predict … Species distribution models (SDMs) are numerical tools that combine observations of species occurrence or abundance with environmental estimates. They are used to gain ecological and evolutionary insights and to predict distributions across landscapes, ...Read More

Rapid and highly variable warming of lake surface waters around the globe

2015-12-16

Catherine M. O’Reilly , Sapna Sharma , Derek K. Gray +7 more

Abstract In this first worldwide synthesis of in situ and satellite‐derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade −1 ) … Abstract In this first worldwide synthesis of in situ and satellite‐derived lake data, we find that lake summer surface water temperatures rose rapidly (global mean = 0.34°C decade −1 ) between 1985 and 2009. Our analyses show that surface water warming rates are dependent on combinations of climate and local characteristics, rather than just lake location, leading to the counterintuitive result that regional consistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widely geographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice‐covered lakes in areas where temperature and solar radiation are increasing while cloud cover is diminishing (0.72°C decade −1 ) to ice‐free lakes experiencing increases in air temperature and solar radiation (0.53°C decade −1 ). The pervasive and rapid warming observed here signals the urgent need to incorporate climate impacts into vulnerability assessments and adaptation efforts for lakes.

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Reducing Phosphorus to Curb Lake Eutrophication is a Success

2016-08-05

David W. Schindler , Stephen R. Carpenter , Steven C. Chapra +2 more

As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of algae are becoming larger and more frequent in freshwater lakes. In most cases, the blooms are predominantly … As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of algae are becoming larger and more frequent in freshwater lakes. In most cases, the blooms are predominantly blue-green algae (Cyanobacteria), which are favored by low ratios of nitrogen to phosphorus. In the past half century, aquatic scientists have devoted much effort to understanding the causes of such blooms and how they can be prevented or reduced. Here we review the evidence, finding that numerous long-term studies of lake ecosystems in Europe and North America show that controlling algal blooms and other symptoms of eutrophication depends on reducing inputs of a single nutrient: phosphorus. In contrast, small-scale experiments of short duration, where nutrients are added rather than removed, often give spurious and confusing results that bear little relevance to solving the problem of cyanobacteria blooms in lakes.

Toxic Cyanobacteria in Water

1999-01-01

Toxic cyanobacteria in water , Toxic cyanobacteria in water , کتابخانه دیجیتال جندی شاپور اهواز Toxic cyanobacteria in water , Toxic cyanobacteria in water , کتابخانه دیجیتال جندی شاپور اهواز

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Widespread global increase in intense lake phytoplankton blooms since the 1980s

2019-10-14

Jeff C. Ho , A. M. Michalak , Nima Pahlevan

Ecological Stoichiometry

2003-12-31

Robert W. Sterner , James J. Elser

All life is chemical. That fact underpins the developing field of ecological stoichiometry, the study of the balance of chemical elements in ecological interactions. This long-awaited book brings this field … All life is chemical. That fact underpins the developing field of ecological stoichiometry, the study of the balance of chemical elements in ecological interactions. This long-awaited book brings this field into its own as a unifying force in ecology and evolution. Synthesizing a wide range of knowledge, Robert Sterner and Jim Elser show how an understanding of the biochemical deployment of elements in organisms from microbes to metazoa provides the key to making sense of both aquatic and terrestrial ecosystems. After summarizing the chemistry of elements and their relative abundance in Earth's environment, the authors proceed along a line of increasing complexity and scale from molecules to cells, individuals, populations, communities, and ecosystems. The book examines fundamental chemical constraints on ecological phenomena such as competition, herbivory, symbiosis, energy flow in food webs, and organic matter sequestration. In accessible prose and with clear mathematical models, the authors show how ecological stoichiometry can illuminate diverse fields of study, from metabolism to global change. Set to be a classic in the field, Ecological Stoichiometry is an indispensable resource for researchers, instructors, and students of ecology, evolution, physiology, and biogeochemistry. From the foreword by Peter Vitousek: ? "[T]his book represents a significant milestone in the history of ecology. . . . Love it or argue with it--and I do both--most ecologists will be influenced by the framework developed in this book. . . . There are points to question here, and many more to test . . . And if we are both lucky and good, this questioning and testing will advance our field beyond the level achieved in this book. I can't wait to get on with it."

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Cyanobacterial blooms

2018-06-26

Jef Huisman , Geoffrey A. Codd , Hans W. Paerl +3 more

Assessment of the diversity, ecology, and spatiotemporal dynamics of the phytoplankton community in the Tono Dam, Ghana

2025-06-24

Emmanuel O. Kombat , Abdul-Wahab M. Imoro , Kezia Baidoo +3 more | Aquatic Ecology

Correction: Melaram et al. Microcystin Contamination and Toxicity: Implications for Agriculture and Public Health. Toxins 2022, 14, 350

2025-06-24

Rajesh Melaram , Amanda Rose Newton , Jennifer Chafin | Toxins

The authors wish to make the following corrections to their paper [...] The authors wish to make the following corrections to their paper [...]

Freshwater Quality Challenges in Southern Europe Under an Increasingly Warmer and Drier Climate Scenario

2025-06-24

Daniela R. de Figueiredo , Sofia Bento , Maria Teresa Condesso de Melo | Water

Climate change is driving major transformations across ecosystems [...] Climate change is driving major transformations across ecosystems [...]

Unraveling the Toxicity of a Non-Microcystin-Producing Strain (CCIBt3106) of Microcystis aeruginosa: Ecotoxicological Effects on Aquatic Invertebrates

2025-06-24

Éryka Costa de Almeida , Fernanda Rios Jacinavicius , Rhuana Valdetário Médice +7 more | Toxins

Cyanobacterial blooms are becoming increasingly frequent and intense worldwide, often dominated by Microcystis aeruginosa, a species capable of producing a wide array of bioactive metabolites beyond microcystins. This study evaluates … Cyanobacterial blooms are becoming increasingly frequent and intense worldwide, often dominated by Microcystis aeruginosa, a species capable of producing a wide array of bioactive metabolites beyond microcystins. This study evaluates the ecotoxicological potential of a non-microcystin-producing strain, M. aeruginosa CCIBt3106, using acute immobilization assays with three microcrustacean species: Daphnia similis, Artemia salina, and Parhyale hawaiensis. Biomass was extracted using solvents of varying polarity, and selected extracts (aqueous and 50% methanol) were further fractionated and analyzed via high-resolution liquid chromatography–tandem mass spectrometry (HR-LC-MS/MS). Significant toxicity was observed in D. similis and P. hawaiensis, with EC50 values ranging from 660 to 940 µg mL−1. Metabolomic profiling revealed the presence of chemically diverse metabolite classes, including peptides, polyketides, and fatty acyls, with putative annotations linked to known bioactivities. These findings demonstrate that cyanobacterial strains lacking microcystins can still produce complex metabolite mixtures capable of inducing species-specific toxic effects under environmentally relevant exposure levels. Overall, the results highlight the need to expand ecotoxicological assessments and monitoring frameworks to include non-microcystin cyanobacterial metabolites and strains in water quality management.

Effect of Rhizoglomus intraradices and symbiotic Bacillus megaterium on the competitive growth of Flaveria bidentis under different soil phosphorus levels

2025-06-24

Ruiyue Wang , Jun Li , Yaning Jia +3 more | Plant and Soil

Spatiotemporal drivers of water quality and phytoplankton communities in a cyanobacteria-dominated reservoir provide management insights

2025-06-23

Linnea A. Rock , William W. Fetzer , Lindsay S. Patterson +4 more | Environmental Monitoring and Assessment

Reservoirs serve critical roles providing drinking water, irrigation, flood control, hydropower, recreation, fisheries, and aquatic habitat. Yet their physical position, complex shape, and large watersheds make reservoirs especially susceptible to … Reservoirs serve critical roles providing drinking water, irrigation, flood control, hydropower, recreation, fisheries, and aquatic habitat. Yet their physical position, complex shape, and large watersheds make reservoirs especially susceptible to eutrophication and harmful algal bloom (HAB) production. Boysen Reservoir, WY, is a high priority for proactive nutrient management because it is an important source for drinking water and recreation, and has a history of toxic cyanobacterial blooms. We combined four years of comprehensive monitoring efforts by state and federal agencies to characterize the spatiotemporal patterns of nutrient inflow, internal water quality dynamics, and phytoplankton community shifts in Boysen Reservoir. We found nutrient inflow was hydrologically driven, with snowmelt runoff transporting high nutrient loads. Our findings suggest physicochemical and nutrient conditions of the reservoir were strongly different between the furthest reaches of the reservoir, but less variable among the intermediate sites. Space did not play a role in phytoplankton community dynamics, but time was an important factor. Cyanobacteria dominated phytoplankton communities by mid-summer across the reservoir and were driven mainly by temporal physicochemical conditions, like stratification and water temperature. The two most dominant phytoplankton taxa across the four years of sampling were N-fixing, toxin producing cyanobacteria. Extensive monitoring efforts and data analyses can illuminate strategies to safeguard water resources via understanding the drivers of water quality changes and HAB production.

Remotely sensed water color and eutrophication in a downstream lake: Long-term dynamic and driving factors in Hong Lake, China

2025-06-23

Xueer Geng , Yadong Zhou , Fan Yang +7 more | Ecological Indicators

Climate factors increasing in importance for internal P dynamics in a large eutrophic lake

2025-06-23

James M. Thompson , Yvonne McElarney , Brian Rippey +3 more | The Science of The Total Environment

Identification and management of ecosystem vulnerability in brackish lakes based on phytoplankton primary productivity dynamics: A case study of lake Nakaumi, Japan

2025-06-23

Xizhe Wang , Kengo Kurata | Journal of Ecological Engineering

Short-term Local Phytoplankton Response to Dredging Effects on a Subtropical Large Lowland River

2025-06-22

Diego Frau , Pablo Collins | Hydrobiologia

Removal of Microcystis aeruginosa using hydrodynamic cavitation in a jet pump cavitation reactor: Considering the mechanical and chemical effects

2025-06-21

Tongshan Chai , Xiaoyu Mo , Shuangjie Xu +3 more | Journal of Environmental Management

Phytoplankton functional groups regulated by hydrological parameters in cascading reservoirs of the subtropical Ganga River, India

2025-06-20

Jeetendra Kumar , Basanta Kumar Das , Asha T. Landge +5 more | Aquatic Ecology

Growth Response of Submerged Macrophyte Vallisneria denseserrulata to Water Depth (Light Intensity) Changes Varies with Sediment Nutrient Level

2025-06-20

Yudan Lin , Jinyang Yu , Haochi Zheng +7 more | Water

The re-establishment of submerged macrophytes is crucial for the ecological restoration of eutrophic lakes. Water depth (light intensity) and sediment nutrient levels are key factors influencing the growth of these … The re-establishment of submerged macrophytes is crucial for the ecological restoration of eutrophic lakes. Water depth (light intensity) and sediment nutrient levels are key factors influencing the growth of these macrophytes. Although their individual impacts have been extensively studied, their interactive effects remain unclear. We conducted a two-factor experiment to investigate the interactive effects of different water depths (50 cm and 190 cm) and sediment nutrient levels (fertile and infertile) on the growth and morphological traits of Vallisneria denseserrulata. We found that biomass, relative growth rate, below/above-ground biomass, ramet number, and leaf number significantly increased with decreasing water depth in fertile sediments, while no significant or less pronounced changes occurred for infertile sediments. The absence or weak responses to increased light intensity in infertile sediments are likely due to photoinhibition, which may be alleviated at higher nutrient levels in fertile sediments. Additionally, V. denseserrulata, in adapting to low-light environments (deeper water), increased plant height at the cost of decreased leaf number and below-ground biomass as water depth increased in fertile sediments. Our study demonstrated significant interactive effects between water depth (light intensity) and sediment nutrient levels on the growth and morphological traits of V. denseserrulata, indicating that their response to water depth (light intensity) strongly depends on sediment fertility.

No evidence of an allelopathic effect of Eurasian watermilfoil ( <i>Myriophyllum spicatum</i> ) on cyanobacteria in two Canadian Lakes

2025-06-20

Colin Bergeron , François Proulx , Sonja Behmel +1 more | Journal of Freshwater Ecology

Phytoplankton as indicators of ecological changes in Afrotropical reservoirs

2025-06-20

Esther N. Akachukwu , Grace E. Obi-Iyeke , Alexander Ikechukwu Ajai +2 more | Environmental Monitoring and Assessment

Decadal changes in water transparency of lakes in the middle and lower reaches of the Yangtze River: Trends and implications

2025-06-19

Zhou Wang , Fei Xiao , Miaomiao Chen +3 more | Ecological Indicators

Editorial: Diversity and stability in aquatic plant communities

2025-06-19

Igor Zelnik , Rui Rivaes , Mateja Germ | Frontiers in Plant Science

Mechanisms of Zooplankton Community Assembly and Their Associations with Environmental Drivers in Arid-Region Reservoirs of Northwest China

2025-06-19

Xuelian Qiu , Fangze Zi , Long Yun +4 more | Biology

This study investigates the mechanisms of zooplankton community assembly and their relationship to environmental factors in high-latitude arid regions. We conducted seasonal sampling at four reservoirs in the upper Tarim … This study investigates the mechanisms of zooplankton community assembly and their relationship to environmental factors in high-latitude arid regions. We conducted seasonal sampling at four reservoirs in the upper Tarim River Basin from 2023 to 2024: Shangyou Reservoir (SY), Shengli Reservoir (SL), Duolang Reservoir (DL) and Xinjingzi Reservoir (XJZ). The zooplankton community was categorized into five functional groups based on the predominant species, with small crustacean filter feeders (SCF) in all reservoirs except XJZ, where a seasonal shift between rotifer collectors (RC) in the wet season and SCF in the dry season was observed. Pearson correlation and canonical correspondence analysis (CCA) revealed that interspecific competition, pH, conductivity (COND), and salinity (SALIN) were the main determinants of zooplankton community composition. Significant correlations (p < 0.05) were detected among functional groups RC (rotifers carnivora), RF (rotifers filter feeders), SCF (small copepods and claocera filter feeders), and MCC (middle copepods and claocera carnivora). Environmental factors showed significant spatial heterogeneity, while zooplankton biomass was positively correlated with pH and COND. Cluster similarity analyses indicated complex interactions between 29 zooplankton species, with RF identified as an important positive predictor for larger groups. The network of co-occurrences showed predominantly positive relationships, emphasizing the mutual facilitation between the species. Our results suggest that interspecific interactions have stronger effects on community structuring than environmental factors, with mutual facilitation emerging as an important survival strategy. This study provides important insights into the dynamics of zooplankton communities in dry reservoirs and establishes a framework for understanding ecological patterns and assembly mechanisms under drought conditions.

Eutrophication Heterogeneously Enhances Organic Matter and Phosphorus Exchanges among Dissolved, Particulate, and Sedimentary Phases in a Large Shallow Lake

2025-06-19

Zhipeng Duan , Liang Jia , Lin Shi +3 more | Environmental Science & Technology

Dissolved, particulate, and sedimentary phases are essential substrates in lake systems. However, few studies have explicitly examined their interactions in response to eutrophication. Here, we characterized organic matter (OM) and … Dissolved, particulate, and sedimentary phases are essential substrates in lake systems. However, few studies have explicitly examined their interactions in response to eutrophication. Here, we characterized organic matter (OM) and phosphorus (P) pools in these subsystems of Lake Taihu and analyzed their variations with a gradient from mesotrophic to hypertrophic states. We employed a "3-subsystem" conceptual model with statistical algorithms to estimate the interactions. Concentrations of dissolved and particulate OM and P increased with eutrophication, while only the surface OM and P pools in sediments exhibited variability with the trophic state. Protein- and humic-like substances in the dissolved and particulate OM pools became more prominent at higher trophic states. High mobile P and low inert P were observed in the suspended particles and surface sediments of eutrophic regions. As the trophic state increased, interactions between dissolved and particulate subsystems and between particulate and sedimentary subsystems strengthened, whereas few changes occurred in the interaction between dissolved and sedimentary subsystems. This suggests that particle release and sediment resuspension are more significant pathways for internal nutrient loading in eutrophic regions. These findings provide a comprehensive understanding of how eutrophication affects lake subsystems and their interactions, offering potential ecological restoration references for eutrophic shallow lakes.

Nonlinear Responses and Population-Level Coupling of Growth and MC-LR Production in Microcystis aeruginosa Under Multifactorial Conditions

2025-06-18

Melina Celeste Crettaz Minaglia , Sandro M. Goñi , Leda Giannuzzi | Phycology

Microcystis aeruginosa is a cyanobacterium frequently associated with toxic blooms in eutrophic freshwater systems. Certain strains produce microcystins (MCs), a group of hepatotoxins with significant ecological and public health implications. … Microcystis aeruginosa is a cyanobacterium frequently associated with toxic blooms in eutrophic freshwater systems. Certain strains produce microcystins (MCs), a group of hepatotoxins with significant ecological and public health implications. In this study, we examined the quantitative response of a temperate native M. aeruginosa strain to combinations of temperature (26, 30, and 36 °C), light intensity (30, 50, and 70 µmol photons·m−2·s−1), and N:P ratio (10, 100, 150), using a full-factorial experimental design. Growth parameters (µ, lag phase duration, and maximum cell density), chlorophyll-a production, and MC-LR synthesis were modeled using Gompertz, linear, and dynamic approaches. High temperature and irradiance increased the specific growth rate but decreased final biomass, while elevated N:P ratios shortened the lag phase. MC-LR production peaked under low temperature, low irradiance, and low N:P ratio. Although MC-LR synthesis did not correlate positively with growth rate, and the environmental conditions maximizing growth differed from those enhancing toxin production, a population-level coupling between both processes was observed using the Long model. These findings suggest that MC-LR synthesis in M. aeruginosa is not merely a metabolic by-product of growth, but a context-dependent trait with potential adaptive significance.

Photochemistry of Lake Taihu dissolved organic matter: Reactive species generation and effects on microcystin photodegradation

2025-06-18

Haishuo Wang , Xiuchun Tian , Jie Zhang +3 more | Journal of Water Process Engineering

A hybrid biomanipulation strategy to regulate seasonal dynamics of phytoplankton in a subtropical mesocosm experiment

2025-06-18

Feng Wang , Wenyi Dong , Hongjie Wang +7 more | The Science of The Total Environment

Prenatal Microcystin-LR Exposure Alters Pancreatic Proteome and Impairs Insulin Secretion in Offspring Mice

2025-06-18

Yu Chen , Guofang Chen , Yijiao Xu +4 more | Toxicology Letters

Phytoplankton functional group dynamics and environmental drivers in a tropical monomictic lake (Lake Yambo, Philippines)

2025-06-17

Dimple May Gianne Q. Dumaguit , Maxine A. D. Mowe , Rey Donne S. Papa | Journal of Limnology

Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, … Tropical monomictic lakes, characterized by a single annual mixing event and prolonged stratification, are particularly sensitive to climatic and anthropogenic pressures. Lake Yambo, a tropical monomictic lake in the Philippines, exemplifies such systems, with stratification prevailing during the southwest monsoon and full lake mixing occurring during the northeast monsoon. This study examined vertical and seasonal variations in environmental conditions and phytoplankton functional group composition in Lake Yambo to assess how seasonal stratification and mixing affect functional groups’ vertical structure. Monthly sampling from March 2024 to February 2025 was conducted from the subsurface to 30 meters at 5-meter intervals. In situ measurements of water temperature, dissolved oxygen, pH, and nitrate (NO₃⁻) were obtained using multiparameter probes, while chlorophyll-a, ammonia, and total phosphorus were analyzed in the laboratory. Phytoplankton samples were collected, identified, and counted, with species comprising at least 5% of the total phytoplankton biomass per period classified into their respective functional groups. Lake Yambo exhibited meso-eutrophic conditions characterized by high total phosphorus concentrations but comparatively low chlorophyll-a levels, suggesting that phytoplankton growth is likely limited by nitrogen availability. Seasonal patterns governed thermal stratification and mixing, which, in turn, regulated vertical nutrient gradients. Stratified conditions during the southwest monsoon led to nutrient trapping and hypolimnetic anoxia, while northeast monsoon mixing redistributed nutrients, particularly NO₃⁻. These transitions strongly influenced the functional group composition. Seven dominant functional groups (B, F, G, H1, J, LO, and P) comprised 81% to 97% of the total phytoplankton biomass. Most functional groups declined with depth, but seasonal and vertical variations were distinct: Group G and H1 thrived in warmer surface waters with low nitrate concentrations. Groups J and LO were associated with cooler, nitrate-enriched surface layers during peak mixing, while Groups B, F, and P were more abundant at deeper layers under the same conditions. These findings support the hypothesis that seasonally driven stratification and mixing in tropical monomictic lakes structure vertical nutrient availability and shape phytoplankton functional group dynamics. Notably, the bloom of Group H1 during post-peak mixing under extreme nitrogen limitation and elevated temperatures poses a health risk, as this group’s descriptor taxon, Dolichospermum, can produce cyanotoxins. Thus, tropical monomictic lakes experiencing greater eutrophication may face increased risks of these toxic blooms. As a representative tropical monomictic system, Lake Yambo offers valuable insights into how similar systems respond to seasonal mixing and nutrient limitations, providing a framework for understanding and managing ecological risks in these environments.

Influence of phosphorus on genome copy number of <i>Synechocystis</i> sp. PCC 6803

2025-06-16

Junkui Zhao , Mengting Wang , Chengwei Liang +1 more | Letters in Applied Microbiology

Abstract The regulatory mechanisms underlying ploidy dynamics in cyanobacteria under phosphorus (P) limitation remain poorly understood. In this study, we investigated the impact of phosphate deprivation on the polyploidy of … Abstract The regulatory mechanisms underlying ploidy dynamics in cyanobacteria under phosphorus (P) limitation remain poorly understood. In this study, we investigated the impact of phosphate deprivation on the polyploidy of Synechocystis sp. PCC 6803 through integrated approaches combining spectrofluorometry, flow cytometry, comparative transcriptomics, Pho regulon prediction, and enzymatic activity assays. Our results revealed a significant reduction in genomic DNA content (p &lt; 0.01) during cultivation in phosphate-free BG11 medium, with average genome copy numbers decreasing from 24.34 ± 0.27 in standard BG11 to 6.18 ± 0.25 under P-depleted conditions (p &lt; 0.01). Transcriptomic analysis demonstrated marked upregulation of genes associated with two-component signaling systems, ABC transporters, and nucleotide metabolism, while DNA replication, homologous recombination, and mismatch repair pathways were significantly downregulated (p &lt; 0.05). Concurrently, alkaline phosphatase activity exhibited a substantial increase (p &lt; 0.01), suggesting enhanced phosphate mobilization. These findings collectively indicated that genome copy number in Synechocystis sp. PCC 6803 was dynamically regulated through the coordinated interplay between DNA replication suppression and degradation activation in response to phosphorus availability. This work provides novel insights into the molecular basis of ploidy regulation in cyanobacteria and offers valuable implications for understanding analogous mechanisms in chloroplasts.

A heterogeneity of water and sediment nitrogen removal patterns in shallow lakes: implications for lake management

2025-06-16

Yuyu Ji , Wenqing Shi , Justin D. Brookes +1 more | Journal of Environmental Management

Using an Ultraviolet-Enabled Boat to Reduce Microcystin and Suppress Cyanobacterial Growth in Harmful Algal Bloom-Impacted Surface Waters

2025-06-16

Taylor Rycroft , Fernando A. Branco , Michael L. Mayo | Applied Sciences

Numerous remediation strategies exist for cyanobacterial harmful algal blooms (cyanoHABs); however, most are limited by challenges of scalability and adverse off-target effects on the surrounding ecosystem. Germicidal ultraviolet light (UV-C) … Numerous remediation strategies exist for cyanobacterial harmful algal blooms (cyanoHABs); however, most are limited by challenges of scalability and adverse off-target effects on the surrounding ecosystem. Germicidal ultraviolet light (UV-C) has emerged as a promising method for suppressing cyanoHABs in a sustainable, chemical-free manner that is both scalable and results in limited off-target ecological effects in the surrounding area. In this study, the US Army Engineer Research and Development Center’s (ERDC)’s CyanoSTUNTM (Cyanobacterial Suppression Through Ultraviolet-Light-C Neutralization) vessel was deployed to a cyanoHAB as part of a field trial to determine whether UV-C could effectively suppress cellular growth, degrade associated cyanotoxins, and inhibit harmful phytoplankton species more readily than beneficial species without the addition of chemicals. The cyanoHAB exhibited an average cyanobacteria abundance of 3.75 × 105 cells/mL (n = 5, SD = 6.76 × 104 cells/mL) and average total microcystin concentration of 3.5 µg/L (n = 5; SD = 0.24 µg/L). Pre- and post-treatment samples were collected and re-grown for 9 days in the laboratory to observe differences in microcystin, chlorophyll a, and phycocyanin concentrations, optical density, cell density, and community composition. The results of the field trial showed that the CyanoSTUN UV-C treatment effectively suppressed the growth of the cyanobacteria community for approximately two days at the three tested UV-C doses. The CyanoSTUN UV-C treatment also demonstrated a sustained, dose-dependent effect on microcystin concentration; the average reduction in microcystin concentration for 15, 30, and 45 mJ/cm2 treatment doses was 31.6% (n = 10, SD = 20.1%; 1.3 µg/L reduced), 45.7% (n = 10, SD = 10.8%; 1.9 µg/L reduced), and 49.9% (n = 10, SD = 8.2%; 1.7 µg/L reduced), respectively, over the 9-day regrowth period. Non-cyanobacteria were too scarce in this CyanoHAB to conclude whether the CyanoSTUN UV-C inhibits harmful phytoplankton species more readily than beneficial species. Further field studies with the CyanoSTUNTM are required to validate performance under more severe cyanoHAB conditions, however the results reported herein from the first field trial with the CyanoSTUNTM suggest that this treatment method may offer water managers confronted with a CyanoHAB the ability to rapidly and safely pause a bloom for multiple days and reduce the risks posed by its associated cyanotoxins without adding chemicals.

Scoping review of the effects of cyanobacterial toxins on human and animal health and potential role in mosquito control

2025-06-14

Luka K. Ndungu , Annette Stubner , Sean P. Beeman +4 more | Discover Environment

Abstract Cyanobacteria and their associated toxins are widespread, particularly in aquatic environments. Periodic comprehensive assessments of the effects of cyanobacteria and cyanotoxin, within the One Health framework is needed. Evidence … Abstract Cyanobacteria and their associated toxins are widespread, particularly in aquatic environments. Periodic comprehensive assessments of the effects of cyanobacteria and cyanotoxin, within the One Health framework is needed. Evidence suggests that increasing presence of cyanobacteria in water bodies enhances mosquito breeding therefore raises interesting questions on how the toxins impact mosquitoes. This review highlights the impacts of cyanobacteria and their toxins on human and animal health, while exploring potential effects and emerging research questions on mosquitoes. We systematically searched peer reviewed publications across PubMed, Web of Science, and Google Scholar, between 1974 and 2023. The publications focused on cyanobacteria and/or cyanotoxin and impacts on human, animal health and arthropods, particularly mosquitoes and were reviewed following PRISMA guidelines. A total of 76 articles were identified with more studies on animal health effects (53%) than on human health (25%) or mosquitoes and other arthropods (22%). Cyanotoxins significantly impact humans and animals by disrupting cellular processes and damaging organs, including the liver, kidneys, and nervous system. In mosquitoes and other arthropods, cyanobacteria and their toxins affect the digestive system and survivorship, suggesting a potential role in mosquito control. This study highlights the impacts of cyanobacteria and their toxins on health and mosquito control but is limited by reliance on in vitro studies and variable methodologies. Future research should focus on field investigations, standardized protocols, molecular tools, and ecological monitoring to enhance understanding and inform One Health-focused interventions and mosquito management strategies.

The Adsorption Characteristics and Impact Mechanism of Phosphorus by Surface Sediments in Natural Freshwater Lakes

2025-06-13

Qiang Zhang , Yang Yang , Xu Liu +1 more | Water

A lake is a sink, source, and converter of phosphorus, and its ability to intercept phosphorus in water bodies is receiving increasing attention. In this study, the Nanyi Lake sediment … A lake is a sink, source, and converter of phosphorus, and its ability to intercept phosphorus in water bodies is receiving increasing attention. In this study, the Nanyi Lake sediment in the middle and lower reaches of the Yangtze River basin was taken as the research object, and the phosphorus adsorption capacity and influencing factors of the sediment in the basin were investigated through a control variable experiment. The adsorption capacities of sediments at the sample points are L1 > L3 > L2, with maximum values of 372.41 mg/kg, 332.53 mg/kg, and 346.27 mg/kg, respectively. Equilibrium adsorption is reached at approximately 5 h for L1 and L2, and 10 h for L3. The interaction between sediment and phosphorus involves physical adsorption and mono-layer adsorption. The increase in temperature does not promote phosphorus migration from overlying water to sediments, but instead triggers phosphorus release from sediments, indicating an exothermic process for phosphorus adsorption on sediments. When the phosphorus concentration in overlying water is below and above 1 mg/L, increasing disturbance intensity results in enhanced phosphorus adsorption and release in sediments, respectively. The presence of humus in the overlying water, especially humic acid compared with fulvic acid, causes stronger adsorption of phosphorus on sediments. Overall, this study contributes to our understanding of phosphorus adsorption characteristics and mechanisms in Nanyi Lake sediments, providing valuable insights for managing and conserving this freshwater ecosystem.

Dispersal of the brachiaria invasive species in a tropical estuary

2025-06-13

Danilo de Oliveira Sant'Ana , Cynara Cunha , Aline Trog Ferreira +1 more | Revista de Geociências do Nordeste

Excess nutrients in estuaries favor the growth of aquatic plants. Invasive plants, such as brachiaria (Urochloa arrecta), increase competition, compromising native species survival and causing ecological imbalance. This study examined … Excess nutrients in estuaries favor the growth of aquatic plants. Invasive plants, such as brachiaria (Urochloa arrecta), increase competition, compromising native species survival and causing ecological imbalance. This study examined the spread of brachiaria in the Guaraguaçu River estuary in Paraná, Brazil, in two scenarios (rainy and dry), considering flow and salinity variations. The brachiaria spread was evaluated using a Lagrangian transport model to simulate inert particle trajectories. Results indicate that in the rainy scenario (lower salinity), particles tend to move more easily out of the modeled domain. In the dry scenario (higher salinity), they tend to remain for over 30 days. These findings show the dynamics of species fixation and adaptation

Nitrogen release potential and ecological environmental effects during particulate matter deposition in sub-deep reservoirs of Southwest China

2025-06-13

Dong Wu , Jingan Chen , Hongyun Bao +5 more | Journal of Hydrology Regional Studies

Halotolerance of Phytoplankton and Invasion Success of Nostocalean Cyanobacteria Under Freshwater Salinization

2025-06-13

Izabelė Šuikaitė , Gabrielė Šiurkutė , Robert Ptáčník +1 more | Microorganisms

Disturbed ecosystems are particularly susceptible to biological invasions. Increasing freshwater salinization, caused by anthropogenic factors, can alter the phytoplankton community and favour newly arrived halotolerant species. This study investigates the … Disturbed ecosystems are particularly susceptible to biological invasions. Increasing freshwater salinization, caused by anthropogenic factors, can alter the phytoplankton community and favour newly arrived halotolerant species. This study investigates the halotolerance of four Nostocalean cyanobacterial species—the native to Europe, Aphanizomenon gracile, and alien Chrysosporum bergii, Cuspidothrix issatschenkoi, and Sphaerospermopsis aphanizomenoides—using monoculture experiments under varying NaCl concentrations. Additionally, we performed two microcosm experiments to explore shifts in biodiversity in freshwater phytoplankton communities sourced from artificial reservoirs and assess their susceptibility to cyanobacterial invasion under salinity stress. Results showed that all Nostocalean cyanobacteria were halotolerant under mild salinities (up to 1 g/L NaCl), with Chrysosporum bergii and Sphaerospermopsis aphanizomenoides demonstrating the most salt tolerance. In the microcosm experiment, changes in community composition were driven by the halotolerance of dominant groups. Water body 1, dominated by Bacillariophytina, reduced its biomass of phytoplankton at high salinity (5 g/L NaCl), while water body 2, dominated by Chlorophytina, remained stable regardless of disturbance. Both cyanobacteria successfully invaded both halotolerant and halosensitive communities, increasing their dominance as salinity rose. Our findings suggest that anthropogenic stressors such as freshwater salinization can alter the phytoplankton community and increase a competitive advantage to certain taxa, including widespread alien cyanobacteria, potentially promoting invasions and bloom formation.

Delayed water quality response to external nutrient loading reduction: the role of internal nutrient loading in a shallow eutrophic lake over 20 years

2025-06-12

Lei Zhao , Su Yufang , Wei Gao +2 more | Ecological Indicators

Variación interanual en las comunidades algales y calidad del agua de una laguna periurbana: Laguna Don Tomás (La Pampa, Argentina)

2025-06-12

Manuela Monteyro , Andrea E. Biasotti , María José Galea +1 more | Cymbella revista de investigación y difusión sobre algas.

Este estudio se realizó en el Parque Recreativo Laguna Don Tomás (Santa Rosa, La Pampa, Argentina) comparando dos períodos comprendidos entre mayo 2019 - febrero 2020 y noviembre 2022 - … Este estudio se realizó en el Parque Recreativo Laguna Don Tomás (Santa Rosa, La Pampa, Argentina) comparando dos períodos comprendidos entre mayo 2019 - febrero 2020 y noviembre 2022 - agosto 2023. Se tomaron muestras en tres puntos de la laguna para evaluar la riqueza ficológica y la calidad del agua a lo largo de las estaciones del año. Se analizaron parámetros físicoquímicos como temperatura, transparencia, pH y conductividad. En el primer período (P1), se identificaron 78 taxones de las clases Chlorophyceae (32), Cyanophyceae (20), Zygnematophyceae (11), Bacillariophyceae (10), Euglenophyceae (4) y Trebouxiophyceae (1). En el segundo período (P2), se registraron 88 taxones, de las Clases Chlorophyceae (39), Cyanophyceae (18), Bacillariophyceae (14), Zygnematophyceae (12), Euglenophyceae (3), Trebouxiophyceae (1) y Dinophyceae (1). Los índices de Nygaard indicaron que la laguna era eutrófica en ambos períodos, con un enriquecimiento de nutrientes en el agua. El índice Plantle & Buck (S=2.52) señaló contaminación orgánica débil (β mesosapróbico) en ambos períodos. El análisis de similitud de las comunidades ficológicas mostró una coincidencia superior al 50 % entre los períodos, y el índice de Jaccard (0.39) reflejó los taxones compartidos entre ambos.

Cladoceran Chydorus sphaericus and Colonial Cyanobacteria: Potentially a Toxic Relationship?

2025-06-12

Helen Agasild , Ilmar Tõnno , Margarita Esmeralda Gonzales Ferraz +6 more | Toxins

Chydorus sphaericus is often a dominant cladoceran zooplankton species in water bodies experiencing harmful cyanobacterial blooms. However, its relationship with toxin-producing algae remains largely unexplored. In this study, the feeding … Chydorus sphaericus is often a dominant cladoceran zooplankton species in water bodies experiencing harmful cyanobacterial blooms. However, its relationship with toxin-producing algae remains largely unexplored. In this study, the feeding behavior of C. sphaericus on colonial cyanobacteria and potentially toxic Microcystis was investigated in a temperate, shallow, eutrophic lake. Liquid chromatographic analyses of phytoplankton marker pigments in C. sphaericus gut content revealed that pigments characteristic of cyanobacteria (identified a zeaxanthin, echinenone, and canthaxanthin) comprised the majority of its diet. Among them, colonial cyanobacteria (marked by the pigment canthaxanthin) were the highly preferred food source despite their minor contribution to phytoplankton biomass. qPCR targeting Microcystis genus-specific mcyE synthase genes, which are involved in microcystin biosynthesis, indicated that potentially toxic strains of Microcystis were present in C. sphaericus gut content throughout its temporal and spatial presence in the lake. The results suggest that the common small cladoceran in eutrophic waters, C. sphaericus, has a close trophic interaction with colonial cyanobacteria (including Microcystis) and may represent an important vector for transferring toxigenic Microcystis to the food web, even under conditions of low Microcystis biomass in the lake water.

Flocculation Efficiency of Organic and Inorganic Coagulants in Microalgae Bloom Harvesting

2025-06-09

C. H. Lee , Paran Gani , Siti Nor Aishah Mohd Salleh +1 more | Deleted Journal

The present study investigated the performance of inorganic (alum) and organic (chitosan) coagulants in the flocculation-harvesting of microalgae blooms. Water samples were collected from the eutrophic Gunung Lang Recreational Park, … The present study investigated the performance of inorganic (alum) and organic (chitosan) coagulants in the flocculation-harvesting of microalgae blooms. Water samples were collected from the eutrophic Gunung Lang Recreational Park, Ipoh, Malaysia. The analysis results indicated moderate contamination, with the early stages of algal bloom suggested by high pH and moderate turbidity. Optimisation of coagulant dosage and pH was carried out through a jar-test experiment and Response Surface Methodology (RSM). The best performance was observed with alum, achieving 98.7% harvesting efficiency at 105 mg/l and pH 8.5, while chitosan reached 86% efficiency at 180 mg/l and pH 5.0. Statistical analysis revealed that pH and dosage significantly impacted flocculation performance. These results demonstrated that alum and chitosan were cost-effective and efficient coagulants. Moreover, chitosan presented a biodegradable alternative, offering environmental sustainability in the long term. This study suggested that flocculation could be a competitive and scalable technique for improving water quality and recovering microalgae biomass, with potential applications in large-scale water treatment.