Nutrient Retention in Ecologically Functional Floodplains: A Review

In several countries, the public health and fishery industries have suffered from harmful algal blooms (HABs) that have escalated to become a global issue. Though computational modeling offers an effective means to understand and mitigate the adverse effects of HABs, it is challenging to design models that adequately reflect the complexity of HAB dynamics. This paper presents a method involving the application of deep learning to an ocean model for simulating blooms of Alexandrium catenella. The classification and regression convolutional neural network (CNN) models are used for simulating the blooms. The classification CNN determines the bloom initiation while the regression CNN estimates the bloom density. GoogleNet and Resnet 101 are identified as the best structures for the classification and regression CNNs, respectively. The corresponding accuracy and root means square error values are determined as 96.8% and 1.20 [log(cells L–1)], respectively. The results obtained in this study reveal the simulated distribution to follow the Alexandrium catenella bloom. Moreover, Grad-CAM identifies that the salinity and temperature contributed to the initiation of the bloom whereas NH4-N influenced the growth of the bloom.

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Tracing the sources of nutrients fueling dinoflagellate red tides occurring along the coast of Korea using radium isotopes

Scientific Reports ◽

10.1038/s41598-019-51623-w ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Hyeong Kyu Kwon ◽

Guebuem Kim ◽

Yongjin Han ◽

Junhyeong Seo ◽

Weol Ae Lim ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Red Tide ◽

Subsurface Layer ◽

Vertical Mixing ◽

Eastern Coast ◽

Nutrient Concentrations ◽

Red Tides ◽

Radium Isotopes ◽

Nutrient Sources

Abstract It is a well held concept that the magnitude of red-tide occurrence is dependent on the amount of nutrient supply if the conditions are same for temperature, salinity, light, interspecific competition, etc. However, nutrient sources fueling dinoflagellate red-tides are difficult to identify since red tides usually occur under very low inorganic-nutrient conditions. In this study, we used short-lived Ra isotopes (223Ra and 224Ra) to trace the nutrient sources fueling initiation and spread of Cochlodinium polykrikoides blooms along the coast of Korea during the summers of 2014, 2016, and 2017. Horizontal and vertical distributions of nutrient concentrations correlated well with 224Ra activities in nutrient-source waters. The offshore red-tide areas showed high 224Ra activities and low-inorganic and high-organic nutrient concentrations, which are favorable for blooming C. polykrikoides in competition with diatoms. Based on Ra isotopes, the nutrients fueling red-tide initiation (southern coast of Korea) are found to be transported horizontally from inner-shore waters. However, the nutrients in the spread region (eastern coast of Korea), approximately 200 km from the initiation region, are supplied continuously from the subsurface layer by vertical mixing or upwelling. Our study highlights that short-lived Ra isotopes are excellent tracers of nutrients fueling harmful algal blooms in coastal waters.

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Photodynamic Controls of Harmful Algal Blooms by an Ultra-efficient and Degradable AIEgen-based Photosensitizer

10.26434/chemrxiv.12471557.v1 ◽

2020 ◽

Author(s):

Qiang Yue ◽

Xuewen He ◽

Neng Yan ◽

sidan tian ◽

Chenchen LIU ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Water Solubility ◽

Irradiation Time ◽

Effective Means ◽

Cost Effective ◽

Weather Conditions ◽

New Paradigm ◽

Green Governance ◽

Positively Charged

Harmful <a></a><a>algal blooms</a> (HAB) have severe impacts on human health, aquatic ecosystems, and economy. There is still a lack of effective means to control the algal blooms. Herein, a positively charged photosensitizer with aggregation induced emission (AIE) characteristics, namely TVP-A, is reported for its super-efficient, cost-effective, and eco-friendly governance of HAB. TVP-A possesses a characteristically high quantum yield of harvesting white light into reactive oxygen species (ROS). Attributed to its positive charges, TVP-A has good water solubility and can quickly adsorb onto algal cells floating on the water surface. It effectively triggers cell death through oxidative destruction of the nuclei and chloroplasts of algae. The extremely low effective concentration of TVP-A and the short irradiation time by natural light in removing algal blooms ensure its application at large scales under most weather conditions, without affecting other existing organisms. The slow but consistent self-degradation of TVP-A during the photodynamic controls of algal blooms avoids generating any environmental residues or secondary pollution to environmental systems. TVP-A thereby serves as an excellent candidate for the green governance of HAB, and this work represents a new paradigm for the development of efficient and degradable AIEgens for future environmental applications.

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Connections and Feedback: Aquatic, Plant, and Soil Microbiomes in Heterogeneous and Changing Environments

BioScience ◽

10.1093/biosci/biaa046 ◽

2020 ◽

Vol 70 (7) ◽

pp. 548-562 ◽

Cited By ~ 1

Author(s):

Walter K Dodds ◽

Lydia H Zeglin ◽

Robert J Ramos ◽

Thomas G Platt ◽

Aakash Pandey ◽

...

Keyword(s):

Ecosystem Services ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Crop Production ◽

Nutrient Retention ◽

Anthropogenic Factors ◽

Aquatic Habitats ◽

Plant Soil ◽

Gas Fluxes ◽

Management Approaches

Abstract Plant, soil, and aquatic microbiomes interact, but scientists often study them independently. Integrating knowledge across these traditionally separate subdisciplines will generate better understanding of microbial ecological properties. Interactions among plant, soil, and aquatic microbiomes, as well as anthropogenic factors, influence important ecosystem processes, including greenhouse gas fluxes, crop production, nonnative species control, and nutrient flux from terrestrial to aquatic habitats. Terrestrial microbiomes influence nutrient retention and particle movement, thereby influencing the composition and functioning of aquatic microbiomes, which, themselves, govern water quality, and the potential for harmful algal blooms. Understanding how microbiomes drive links among terrestrial (plant and soil) and aquatic habitats will inform management decisions influencing ecosystem services. In the present article, we synthesize knowledge of microbiomes from traditionally disparate fields and how they mediate connections across physically separated systems. We identify knowledge gaps currently limiting our abilities to actualize microbiome management approaches for addressing environmental problems and optimize ecosystem services.

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The Case for Phosphorus

Dead Zones ◽

10.1093/oso/9780197520376.003.0008 ◽

2021 ◽

pp. 106-123

Author(s):

David L. Kirchman

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Wastewater Treatment Plants ◽

Action Plan ◽

Dead Zone ◽

Cyanobacterial Blooms ◽

Nutrient Concentrations ◽

Marine Microorganisms ◽

Nitrogen And Phosphorus ◽

The Baltic

As this chapter explains, one approach to evaluate nutrient limitation is to compare nutrient concentrations with the Redfield ratio. Alfred Redfield had no formal background in oceanography, yet he made one of the most fundamental discoveries in the field. He found that the ratio of nitrogen to phosphorus in marine microorganisms is the same as the ratio of the two elements in nutrients dissolved in the oceans. Because of work with the ratio, the current Hypoxia Action Plan for the Gulf of Mexico mentions phosphorus as well as nitrogen. In the Baltic Sea, it was argued that the focus should be solely on phosphorus to limit toxic cyanobacterial blooms, but other work demonstrates the importance of limiting nitrogen for minimizing eutrophication. Once considered to be a dead lake, Lake Erie improved after the construction of wastewater-treatment plants and the banning of phosphorus-rich detergents, as the chapter shows. But the lake continues to have problems with hypoxia and harmful algal blooms, because of continuing inputs of phosphate and organic nitrogen. The chapter ends by arguing that both nitrogen and phosphorus must be considered in efforts to solve the dead-zone problem.

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Anticipated human population and climate change effects on algal blooms of a toxic haptophyte in the south-central USA1This article is derived from a special session entitled “A New Hydrology: Inflow Effects on Ecosystem Form and Functioning” that took place at the February 2011 ASLO Aquatic Sciences conference in San Juan, Puerto Rico.

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2012-019 ◽

2012 ◽

Vol 69 (8) ◽

pp. 1389-1404 ◽

Cited By ~ 22

Author(s):

Daniel L. Roelke ◽

Bryan W. Brooks ◽

James P. Grover ◽

George M. Gable ◽

Leslie Schwierzke-Wade ◽

...

Keyword(s):

Climate Change ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Human Population ◽

Nutrient Concentrations ◽

Prymnesium Parvum ◽

Climate Change Effects ◽

South Central ◽

Resource Managers ◽

Aquatic Sciences

Effects of inflow on phytoplankton dynamics and assemblage structure have long been an interest of ecologists and resource managers, especially when they are linked to the incidence of harmful algal blooms. The frequency and magnitude of Prymnesium parvum bloom-preventing inflows likely in a drier landscape of south-central USA was explored, along with the relative importance of various factors important to blooms. We show that the number of large inflow events necessary to prevent blooms might decrease between 25% and 65% under drier conditions likely for this region. Long duration inflow events that are critical to lake flushing could nearly disappear, with inflow events lasting longer than 20 days decreasing 40-fold. These findings suggest that the frequency of P. parvum blooms and fish-kill events might increase in this region with human population and climate change. Multivariate analyses of monitoring data from multiple lakes indicate that other factors may be equally important to bloom occurrences. Inverse trends between toxic bloom events and nutrient concentrations, cyanobacteria, and lower pH are apparent. During periods when P. parvum populations were not toxic, an inverse relationship with zooplankton was observed. These other factors might be harnessed to mitigate P. parvum blooms in the future when inflows are reduced.

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Population dynamics of harmful algal blooms in Lake Champlain: A tale of two phases

10.7287/peerj.preprints.75v1 ◽

2013 ◽

Author(s):

Edmund Hart ◽

Nicholas Gotelli ◽

Rebecca Gorney ◽

Mary Watzin

Keyword(s):

Population Growth ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Time Series Data ◽

Growth Parameters ◽

Series Data ◽

Nutrient Concentrations ◽

Nutrient Inputs ◽

Lake Champlain ◽

Two Phases

Understanding the dynamics of harmful algal blooms (HABs) in lakes can inform management strategies to reduce their economic and health impacts. Previous studies have analyzed spatially replicated samples from a single time or have fit phenomenological models to time series data. We fit mechanistic population models to test the effects of critical nutrient concentrations and the density of potential algal competitors on population growth parameters in HABs in Lake Champlain, U.S.A. We fit models to five years (2003-2006, 2008) of weekly cyanobacteria counts. Plankton dynamics exhibited two phases of population growth: an initial “bloom phase” of rapid population growth and a subsequent “post-bloom phase” of stochastic decline. Population growth rates in the bloom phase were strongly density dependent and increased with increasing TN:TP ratios. The post-bloom phase was largely stochastic and was not obviously related to nutrient concentrations. Because TN:TP was important only in the initial phase of population growth, correlative analyses of the relationship between cyanobacteria blooms and nutrient concentrations may be especially sensitive to when snapshot data are collected. Limiting nutrient inputs early in the season could be an effective management strategy for suppressing or reducing the bloom phase of cyanobacteria population growth.

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Photodynamic Controls of Harmful Algal Blooms by an Ultra-efficient and Degradable AIEgen-based Photosensitizer

10.26434/chemrxiv.12471557 ◽

2020 ◽

Author(s):

Qiang Yue ◽

Xuewen He ◽

Neng Yan ◽

sidan tian ◽

Chenchen LIU ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Water Solubility ◽

Irradiation Time ◽

Effective Means ◽

Cost Effective ◽

Weather Conditions ◽

New Paradigm ◽

Green Governance ◽

Positively Charged

Harmful <a></a><a>algal blooms</a> (HAB) have severe impacts on human health, aquatic ecosystems, and economy. There is still a lack of effective means to control the algal blooms. Herein, a positively charged photosensitizer with aggregation induced emission (AIE) characteristics, namely TVP-A, is reported for its super-efficient, cost-effective, and eco-friendly governance of HAB. TVP-A possesses a characteristically high quantum yield of harvesting white light into reactive oxygen species (ROS). Attributed to its positive charges, TVP-A has good water solubility and can quickly adsorb onto algal cells floating on the water surface. It effectively triggers cell death through oxidative destruction of the nuclei and chloroplasts of algae. The extremely low effective concentration of TVP-A and the short irradiation time by natural light in removing algal blooms ensure its application at large scales under most weather conditions, without affecting other existing organisms. The slow but consistent self-degradation of TVP-A during the photodynamic controls of algal blooms avoids generating any environmental residues or secondary pollution to environmental systems. TVP-A thereby serves as an excellent candidate for the green governance of HAB, and this work represents a new paradigm for the development of efficient and degradable AIEgens for future environmental applications.

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sxtA-Based Quantitative Molecular Assay To Identify Saxitoxin-Producing Harmful Algal Blooms in Marine Waters

Applied and Environmental Microbiology ◽

10.1128/aem.05308-11 ◽

2011 ◽

Vol 77 (19) ◽

pp. 7050-7057 ◽

Cited By ~ 67

Author(s):

Shauna A. Murray ◽

Maria Wiese ◽

Anke Stüken ◽

Steve Brett ◽

Ralf Kellmann ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Harmful Algal Bloom ◽

Effective Means ◽

Molecular Genetic ◽

Alexandrium Tamarense ◽

Alexandrium Catenella ◽

Content Type ◽

Eukaryotic Phytoplankton ◽

Novel Method

ABSTRACTThe recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal bloomsin situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the genesxtAthat encodes a unique enzyme putatively involved in thesxtpathway in marine dinoflagellates,sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producingAlexandriumandGymnodinium catenatumand was not detected in the non-STX-producingAlexandriumspecies, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However,sxtA4was also detected in the non-STX-producing strain ofAlexandrium tamarense, Tasmanian ribotype. We investigated the copy number ofsxtA4in three strains ofAlexandrium catenellaand found it to be relatively constant among strains. Using our novel method, we detected and quantifiedsxtA4in three environmental blooms ofAlexandrium catenellathat led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring.

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