Growth performance of Alexandrium catenella from the Chilean fjords under different environmental drivers: plasticity as a response to a highly variable environment

2020 ◽  
Vol 42 (2) ◽  
pp. 119-134 ◽  
Author(s):  
Javier Paredes-Mella ◽  
Daniel Varela ◽  
Pamela Fernández ◽  
Oscar Espinoza-González
Keyword(s):  
Light Intensity ◽  
Growth Performance ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Optimal Growth ◽  
N:P Ratio ◽  
Environmental Drivers ◽  
Growth Responses ◽  
Variable Environment ◽  
Alexandrium Catenella

Abstract Alexandrium catenella, the main species associated with harmful algal blooms, has progressively increased its distribution through one of the most extensive and highly variable fjord systems in the world. In order to understand this successful expansion, we evaluated the effects of different salinities, light intensity, temperatures, nitrogen (N) forms and nitrogen/phosphate (N:P) ratio levels on the growth performance, using clones isolated from different locations across its wide geographic distribution. Results showed that the growth responses were plastic and, in some cases, different reaction norms among clones were observed. Despite plasticity, the optimal growth of A. catenella (i.e. highest growth rate and highest maximal cells density) was reached within a narrow thermal range (12–15°C), while salinity (20–30 PSU) and light intensity (20–120 μmol m−2 s−1) ranges were wider. These results are partially consistent with the highest cell densities recorded in the field. Furthermore, optimal growth was reached using reduced forms of nitrogen (i.e. urea and NH4+) and in unbalanced N:P ratios (18:1 and 30:1). These characteristics likely allow A. catenella to grow in highly variable environmental conditions and might partly explain the recent expansion of this species.

scholarly journals Deep Learning for Simulating Harmful Algal Blooms Using Ocean Numerical Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Sang-Soo Baek ◽  
JongCheol Pyo ◽  
Yong Sung Kwon ◽  
Seong-Jun Chun ◽  
Seung Ho Baek ◽  
...  
Keyword(s):  
Deep Learning ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Effective Means ◽  
Ocean Model ◽  
Alexandrium Catenella ◽  
The Public ◽  
Global Issue ◽  
Simulated Distribution ◽  
Classification And Regression

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.

Influence of non-nutrient environmental factors on Ulva pertusa's inhibitory effects on Heterosigma akashiwo growth

2015 ◽  
Vol 96 (5) ◽  
pp. 1041-1052
Author(s):  
Qiu Jin ◽  
Han-Gui Wu ◽  
Xin-Xin Zhang ◽  
Zhong-Lu Ke
Keyword(s):  
Environmental Factors ◽  
Growth Inhibition ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Optimal Growth ◽  
High Irradiance ◽  
Heterosigma Akashiwo ◽  
Inhibitory Influence ◽  
Single Factor ◽  
Green Macroalgae

We studied the effects of four non-nutrient environmental factors (temperature, salinity, irradiance and pH) on the growth inhibition of the macroalgae Ulva pertusa (Chlorophyta) upon the microalgae Heterosigma akashiwo (Rhaphidophyta). Experiments were conducted in single-factor incubation and various two-factor combination experiments in which temperature (10, 15, 25 and 30°C), salinity (10, 20, 30 and 40 g kg−1 water), irradiance (20, 100, 200 and 400 μmol m−2 s−1), and pH (5.5, 7, 8.5 and 10) were varied systematically. The growth rates of U. pertusa and H. akashiwo and the rate of microalgal growth inhibition were altered significantly by changing some of the non-nutrient factors in both the single-factor and the two-factor experiments. The optimal growth conditions for U. pertusa were 20–25°C, salinity of 30 g kg−1, irradiance level of 200–400 μmol m−2 s−1, and pH 8.5–10; optimal conditions for H. akashiwo growth were 25°C, 30 g kg−1, 100 μmol m−2 s−1 and pH 8.5, respectively. The growth inhibitory influence of U. pertusa on H. akashiwo was strongest at 25°C with low salinity (10 g kg−1), high irradiance (400 μmol m−2 s−1) and high alkalinity (pH = 10). The results of this study may be helpful in the development of methods for using green macroalgae to control the proliferation of microalgae in harmful algal blooms (HABs). In particular, these findings provide guidance regarding optimum levels of non-nutrient environmental factors in confined areas, such as aquaculture factories.

scholarly journals Nutrient Control to Prevent the Occurrence of Cyanobacterial Blooms in a Eutrophic Lake in Southern Sweden, Used for Drinking Water Supply

2018 ◽  
Author(s):  
Jing Li ◽  
Lars-Anders Hansson ◽  
Kenneth M. Persson
Keyword(s):  
Total Phosphorus ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Cyanobacterial Bloom ◽  
Eutrophic Lake ◽  
N:P Ratio ◽  
Cyanobacterial Blooms ◽  
Southern Sweden ◽  
Dissolved Phosphorus ◽  
Future Work

Control of nutrients, mainly nitrogen (N) and phosphorus (P), plays a significant role in preventing cyanobacterial blooms (harmful algal blooms (HABs)). This study aimed at evaluating changes in the risk of the occurrence of cyanobacterial blooms and advancing the understanding of how N and P affect the growth of cyanobacteria in a eutrophic lake, Lake Vombsjön, in southern Sweden. Statistical analysis was used to demonstrate the pattern of cyanobacterial blooms, that the highest content present in September and the later that algal blooms occur, the more likely it is a cyanobacterial bloom as cyanobacteria became dominating in October and November (90%). Two hypothesises tested in Lake Vombsjön confirmed namely that a high total phosphorus (TP) level correlates with an abundance of cyanobacteria and that low N:P ratio (total nitrogen/total phosphorus < 20) favours the growth of cyanobacteria. To control the growth of cyanobacteria in Lake Vombsjön, the TP level should be kept below 20 µg/L and the N:P ratio be maintained at a level of over 20. The two species Planktothrix agardhii, and Pseudanabaena spp. should be carefully monitored especially in late autumn. Future work should consider any high degree of leakage from the sediment of the dissolved phosphorus available there.

scholarly journals The effect of iron on Chilean Alexandrium catenella growth and paralytic shellfish toxin production as related to algal blooms

BioMetals ◽  
2021 ◽  
Author(s):  
Kyoko Yarimizu ◽  
Jorge I. Mardones ◽  
Javier Paredes-Mella ◽  
Luis Norambuena-Subiabre ◽  
Carl J. Carrano ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Culture Media ◽  
Iron Concentration ◽  
Toxin Production ◽  
Southern Chile ◽  
Alexandrium Catenella ◽  
Paralytic Shellfish Toxin ◽  
Paralytic Shellfish ◽  
Shellfish Toxin

AbstractThe dinoflagellate Alexandrium catenella is a well-known paralytic shellfish toxin producer that forms harmful algal blooms (HABs) worldwide. Blooms of this species have repeatedly brought severe ecological and economic impacts to Chile, especially in the southern region, where the shellfish and salmon industries are world-famous. The mechanisms of such HABs have been intensively studied but are still unclear. Nutrient overloading is one of the often-discussed drivers for HABs. The present study used the A. catenella strain isolated from southern Chile to investigate how iron conditions could affect their growth and toxin production as related to HAB. Our results showed that an optimum concentration of iron was pivotal for proper A. catenella growth. Thus, while excess iron exerted a toxic effect, low iron media led to iron insufficiency and growth inhibition. In addition, the study shows that the degree of paralytic shellfish toxin production by A. catenella varied depending on the iron concentration in the culture media. The A. catenella strain from southern Chile produced GTX1-4 exclusively in the fmol cell−1 scale. Based on these findings, we suggest that including iron and paralytic shellfish toxin measurements in the fields can improve the current HAB monitoring and contribute to an understanding of A. catenella bloom dynamics in Chile.

scholarly journals Kelimpahan Dinoflagellata Bentik Berbahaya di Habitat Lamun dan Makroalga di Pulau Pari, Kepulauan Seribu, Indonesia

2021 ◽  
Vol 6 (3) ◽  
pp. 191
Author(s):  
Mochamad Ramdhan Firdaus ◽  
Arief Rachman ◽  
Oksto Ridho Sianturi ◽  
Diah Anggraini Wulandari ◽  
Hanny Meirinawati ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Principal Component ◽  
N:P Ratio ◽  
Artificial Substrates ◽  
Marine Biota ◽  
Nitrogen And Phosphorus ◽  
Benthic Dinoflagellates ◽  
Fish Poisoning ◽  
Benthic Ecosystems

<p class="Papertext"><strong>The Abundance of the Harmful Benthic Dinoflagellate in the Seagrass and Macroalgae Habitats on Pari Island, Thousand Islands, Indonesia. </strong>Benthic dinoflagellates are an important part of benthic ecosystems and part of their ecological functions. However, ciguatoxin (CTX) producer dinoflagellates, which could cause Ciguatera Fish Poisoning (CFP) disease, is a known threat to marine biota and the island’s coastal communities, such as in Pari Island. Thus, this research aimed is to study the population of five harmful and toxin producer benthic dinoflagellate genera, namely <span style="text-decoration: underline;">Amphidinium</span>, <span style="text-decoration: underline;">Coolia</span>, <span style="text-decoration: underline;">Gambierdiscus</span>, <span style="text-decoration: underline;">Ostreopsis</span>, and <span style="text-decoration: underline;">Prorocentrum</span>, in macroalgae and seagrass habitats of Pari Island. Benthic dinoflagellate samples were collected in Juni 2019 using artificial substrates in the form of a 10×15 cm nylon screen. Environmental variables, such as nutrient concentration (nitrogen and phosphorus) and water temperature were also measured. The results showed that the average benthic dinoflagellate density in seagrass habitats was four times higher compared to the macroalgae habitats. <em>Gambierdiscus</em> were found as the most abundant benthic dinoflagellate in seagrass habitats, while <em>Prorocentrum</em> were more abundant in macroalgae habitats. Principal Component Analysis (PCA) showed that the N:P ratio was the most important regulating parameter for most benthic dinoflagellate genera in this study, except <em>Ostreopsis</em>, which was found to be more abundant in phosphorus-rich macroalga habitats. The data also shows an increase of benthic dinoflagellate cell density up to seven times compared to the previous research data in 2012 and 2013. That trend indicates an increase in the disturbance and pressure on the macroalgae and seagrass habitats of Pari Island, which require special attention to prevent the occurrence of toxic Benthic Harmful Algal Blooms (bHABs) and CFP cases in the island.</p>

scholarly journals Transcriptional Responses of Flavin-Containing Monooxygenase Genes in Scallops Exposed to PST-Producing Dinoflagellates Implying Their Involvements in Detoxification

2021 ◽  
Vol 8 ◽  
Author(s):  
Lingling Kong ◽  
Pingping Liu ◽  
Moli Li ◽  
Huizhen Wang ◽  
Jiaoxia Shi ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Chlamys Farreri ◽  
Transcriptional Responses ◽  
Patinopecten Yessoensis ◽  
Alexandrium Catenella ◽  
Paralytic Shellfish Toxins ◽  
Paralytic Shellfish ◽  
Genome Screening ◽  
Trochophore Stage

Flavin-containing monooxygenase (FMO) is one of the most prominent xenobiotic metabolic enzymes. It can catalyze the conversion of heteroatom-containing chemicals to polar, readily excretable metabolites and is considered an efficient detoxification system for xenobiotics. Bivalves can accumulate paralytic shellfish toxins (PSTs) produced by dinoflagellates, especially during outbreaks of harmful algal blooms. Exploring FMO genes in bivalves may contribute to a better understanding of the adaptation of these species and the mechanisms of PSTs bioavailability. Therefore, through genome screening, we examined the expansion of FMO genes in two scallops (Patinopecten yessoensis and Chlamys farreri) and found a new subfamily (FMO_like). Our expression analyses revealed that, in both scallops, members of the FMO_N-oxide and FMO_like subfamilies were mainly expressed from the D-stage larvae to juveniles, whereas the FMO_GS-OX subfamily genes were mainly expressed at and prior to the trochophore stage. In adult organs, higher expressions of FMOs were observed in the kidney and hepatopancreas than in other organs. After exposure to PST-producing algae, expression changes in FMOs occurred in hepatopancreas and kidney of both scallops, with more members being up-regulated in hepatopancreas than in kidney for Alexandrium catenella exposure, while more up-regulated FMOs were found in kidney than in hepatopancreas of C. farreri exposed to A. minutum. Our findings suggest the adaptive functional diversity of scallop FMO genes in coping with the toxicity of PST-producing algae.

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

2011 ◽  
Vol 77 (19) ◽  
pp. 7050-7057 ◽  
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.

scholarly journals Suitcase Lab: new, portable, and deployable equipment for rapid detection of specific harmful algae in Chilean coastal waters

2020 ◽  
Author(s):  
So Fujiyoshi ◽  
Kyoko Yarimizu ◽  
Yohei Miyashita ◽  
Joaquín Rilling ◽  
Jacquelinne J. Acuña ◽  
...  
Keyword(s):  
Coastal Waters ◽  
Rapid Detection ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Lamp Assay ◽  
Field Studies ◽  
Harmful Algae ◽  
Molecular Diagnostic ◽  
Alexandrium Catenella ◽  
Molecular Diagnostic Test

AbstractPhytoplankton blooms, including harmful algal blooms (HABs), have serious impacts on ecosystems, public health, and productivity activities. Rapid detection and monitoring of marine microalgae are important in predicting and managing HABs. We developed a toolkit, the Suitcase Lab, to detect harmful algae species in the field. We demonstrated the Suitcase Lab’s capabilities for sampling, filtration, DNA extraction, and loop-mediated isothermal amplification (LAMP) detection in cultured Alexandrium catenella cells as well as Chilean coastal waters from four sites: Repollal, Isla García, Puerto Montt, and Metri. A LAMP assay using the Suitcase Lab in the field confirmed microscopic observations of A. catenella in samples from Repollal and Isla García. The Suitcase Lab allowed the rapid detection of A. catenella, within 2 h from the time of sampling, even at a single cell per milliliter concentrations, demonstrating its usefulness for quick and qualitative on-site diagnosis of target toxic algae species. This method is applicable not only to detecting harmful algae but also to other field studies that seek a rapid molecular diagnostic test.

scholarly journals Nutrient content and stoichiometry of pelagic Sargassum reflects increasing nitrogen availability in the Atlantic Basin

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. E. Lapointe ◽  
R. A. Brewton ◽  
L. W. Herren ◽  
M. Wang ◽  
C. Hu ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Nitrogen Availability ◽  
North Atlantic Ocean ◽  
Nutrient Content ◽  
N:P Ratio ◽  
N Availability ◽  
Brown Macroalgae ◽  
The North ◽  
P Limitation

AbstractThe pelagic brown macroalgae Sargassum spp. have grown for centuries in oligotrophic waters of the North Atlantic Ocean supported by natural nutrient sources, such as excretions from associated fishes and invertebrates, upwelling, and N2 fixation. Using a unique historical baseline, we show that since the 1980s the tissue %N of Sargassum spp. has increased by 35%, while %P has decreased by 44%, resulting in a 111% increase in the N:P ratio (13:1 to 28:1) and increased P limitation. The highest %N and δ15N values occurred in coastal waters influenced by N-rich terrestrial runoff, while lower C:N and C:P ratios occurred in winter and spring during peak river discharges. These findings suggest that increased N availability is supporting blooms of Sargassum and turning a critical nursery habitat into harmful algal blooms with catastrophic impacts on coastal ecosystems, economies, and human health.

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