scholarly journals A novel random forest approach to revealing interactions and controls on chlorophyll concentration and bacterial communities during coastal phytoplankton blooms

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yiwei Cheng ◽  
Ved N. Bhoot ◽  
Karl Kumbier ◽  
Marilou P. Sison-Mangus ◽  
James B. Brown ◽  
...  
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Chlorophyll Concentration ◽  
Ecosystem Structure ◽  
Monterey Bay ◽  
Phytoplankton Abundance ◽  
Abundance Patterns ◽  
Machine Learning Model ◽  
Marine Algal ◽  
Coastal Phytoplankton

AbstractIncreasing occurrence of harmful algal blooms across the land–water interface poses significant risks to coastal ecosystem structure and human health. Defining significant drivers and their interactive impacts on blooms allows for more effective analysis and identification of specific conditions supporting phytoplankton growth. A novel iterative Random Forests (iRF) machine-learning model was developed and applied to two example cases along the California coast to identify key stable interactions: (1) phytoplankton abundance in response to various drivers due to coastal conditions and land-sea nutrient fluxes, (2) microbial community structure during algal blooms. In Example 1, watershed derived nutrients were identified as the least significant interacting variable associated with Monterey Bay phytoplankton abundance. In Example 2, through iRF analysis of field-based 16S OTU bacterial community and algae datasets, we independently found stable interactions of prokaryote abundance patterns associated with phytoplankton abundance that have been previously identified in laboratory-based studies. Our study represents the first iRF application to marine algal blooms that helps to identify ocean, microbial, and terrestrial conditions that are considered dominant causal factors on bloom dynamics.

scholarly journals Agricultural Conservation Practices and Aquatic Ecological Responses

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1687
Author(s):  
Richard E. Lizotte ◽  
Peter C. Smiley ◽  
Robert B. Gillespie ◽  
Scott S. Knight
Keyword(s):  
Aquatic Ecosystems ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Soil Health ◽  
Conservation Agriculture ◽  
Agricultural Runoff ◽  
The United States ◽  
Ecosystem Structure ◽  
Ecological Responses ◽  
And Function

Conservation agriculture practices (CAs) have been internationally promoted and used for decades to enhance soil health and mitigate soil loss. An additional benefit of CAs has been mitigation of agricultural runoff impacts on aquatic ecosystems. Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.

scholarly journals Assessing the Skills of a Seasonal Forecast of Chlorophyll in the Global Pelagic Oceans

2021 ◽  
Vol 13 (6) ◽  
pp. 1051
Author(s):  
Cecile S. Rousseaux ◽  
Watson W. Gregg ◽  
Lesley Ott
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Chlorophyll Concentration ◽  
Correlation Coefficients ◽  
Global Scale ◽  
Seasonal Forecasts ◽  
Mean Square Errors ◽  
Satellite Chlorophyll

While forecasts of atmospheric variables, and to a lesser degree ocean circulation, are relatively common, the forecast of biogeochemical conditions is still in its infancy. Using a dynamical ocean biogeochemical forecast forced by seasonal forecasts of atmospheric and physical ocean variables, we produce seasonal predictions of chlorophyll concentration at the global scale. Results show significant Anomaly Correlation Coefficients (ACCs) for the majority of regions (11 out of the 12 regions for the 1-month lead forecast). Root mean square errors are smaller (<0.05 µg chlorophyll (chl) L−1) in the Equatorial regions compared to the higher latitudes (range from 0.05 up to 0.13 µg chl L−1). The forecast for all regions except three (North Atlantic, South Pacific and North Indian) are within the Semi-Interquartile Range of the satellite chlorophyll concentration (Suomi-National Polar-orbiting Partnership (NPP), 27.9%). This suggests the potential for skillful global biogeochemical forecasts on seasonal timescales of chlorophyll, primary production and harmful algal blooms that could support fisheries management and other applications.

scholarly journals Distribución espacial y temporal del fitoplancton en el golfo de Cariaco, estado Sucre, Venezuela, febrero 2014 – enero 2015

2018 ◽  
Vol 47 (2) ◽  
Author(s):  
Asdrúbal Calvo-Trujillo ◽  
Karla Rincones-Reyes ◽  
José Rafael Díaz-Ramos ◽  
Brightdoom Márquez-García ◽  
Sonia Subero-Pino ◽  
...  
Keyword(s):  
Phytoplankton Community ◽  
Transition Period ◽  
Chlorophyll Concentration ◽  
Temporal Distribution ◽  
Nonparametric Analysis ◽  
Multivariate Methods ◽  
Phytoplankton Abundance ◽  
Relaxation Period ◽  
Coastal Phytoplankton ◽  
First Time

Coastal phytoplankton is affected by natural and anthropic processes. To analyze the influence of some of these processes, the spatial and temporal distribution of phytoplankton in the Gulf of Cariaco, Sucre state, was evaluated. Samples (0-10 m) were collected with Niskinbottles (5 L) in seven stations between February 2014 and January 2015. Transparency (m), salinity (UPS), temperature (° C), chlorophyll concentration a (mg m-3), and phytoplankton abundance (org mL-1) were measured. A nonparametric analysis of variance and multivariate methods (PCA, CCA, and nMDS) were used to analyze the results. The 0 - 10 m stratum was homogeneous with respect to all variables except temperature which ranged from 20.1 to 29.1 °C (March and October, respectively). Temporally, the variables were heterogeneous. Biomass fluctuated between undetectable (ND) and 17.5 mg m-3 (December and March). While microalgal abundance oscillated between 0.24 and 1.85 x 103 org mL-1 (April andFebruary). The community was dominated by diatoms, nanoflagellates, and coccolithophorids. The first two groups were associated with turbulent, nutrient-rich waters. The nMDS separated the community into the three periods previously described for the region. Likewise, the CCA detected that wind speed and temperature were the most influential variables on the phytoplankton community during upwelling and relaxation period, respectively. In the transition period, none of the variables studied affected the community. This is the first time that coccolithophores are reported as part of the dominant flora in the Gulf of Cariaco. This change suggests modifications in the oceanographic conditions of the study area.

Viewpoints of Dominant Environmental Factors Influencing Algal Blooms

2011 ◽  
Vol 66-68 ◽  
pp. 155-159
Author(s):  
Di Guan ◽  
Da Wen Gao ◽  
Nan Qi Ren ◽  
Yi Fan Li
Keyword(s):  
Environmental Factors ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Meteorological Factors ◽  
Chlorophyll Concentration ◽  
Phytoplankton Growth ◽  
High Biomass ◽  
Coupling Effects ◽  
Factors Influencing

Harmful algal blooms (HABs) are generally known as excessive phytoplankton growth or rapidly concentrate to high biomass. This study summarized the situation of HABs in China, and discussed possible dominant factors stimulating algal blooms by analyzing several actual HABs cases. It was manifested nutrients may affect algae concentration principally, but such impact tended to decease with degradation of background water. Meanwhile the hydrological and meteorological factors expressed greater correlation to chlorophyll concentration under multiple coupling effects of complex environmental factors. For the complex mechanisms, the determination of principle factors which stimulate excessive algal blooms effectively still need further researches, which are suggested to conduct under overall considerations on 3 scales: macro dimension, medium dimension and micro dimension.

scholarly journals Identification and Monitoring of Microalgal Genera Potentially Capable of Forming Harmful Algal Blooms in Punta Galeta, Panama

2019 ◽  
Vol 12 ◽  
pp. 117862211987276 ◽  
Author(s):  
Alexander González ◽  
Kathia Broce ◽  
José Fábrega-Duque ◽  
Nathalia Tejedor-Flores ◽  
Karen Young
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Growth Parameters ◽  
Harmful Algal Bloom ◽  
Health Hazard ◽  
Artificial Substrates ◽  
Easy Access ◽  
Host Preferences ◽  
Photosynthetic Organisms ◽  
Abundance Patterns

Coastal areas are attractive for human settlements because they allow easy access to benefits like food, security, and fishing. These aquatic ecosystems are supported by photosynthetic organisms that constitute the base of the food web. The term “Harmful Algal Bloom” (HAB) refers to the excessive proliferation of some taxa of these microorganisms reaching harmful levels to humans and other organisms. Biotoxins produced by these HABs could be transferred to the food chain and are the best-documented impact that HABs have on humans. The location and abundance of the HAB species producing the toxin is a good indicator of a possible human health hazard. The aim of this study was to monitor potentially harmful benthic/epibenthic microalgae in Punta Galeta, Panama over a 15-month period. The 3 main microalgae found were 2 dinoflagellates from the genera Prorocentrum and Ostreopsis and 1 diatom from the genus Coscinodiscus. Sampling made with both natural and artificial substrates yielded similar overall abundance patterns; however, for the macroalgae samples, there appeared to be significant host preferences for Ostreopsis and Coscinodiscus. Physicochemical measures taken at the site were found to fall within previously reported growth parameters for the microalgae found in the study.

scholarly journals The Effects of Ocean Acidification and Warming on Growth of a Natural Community of Coastal Phytoplankton

2020 ◽  
Vol 8 (10) ◽  
pp. 821
Author(s):  
Bonggil Hyun ◽  
Ja-Myung Kim ◽  
Pung-Guk Jang ◽  
Min-Chul Jang ◽  
Keun-Hyung Choi ◽  
...  
Keyword(s):  
Species Composition ◽  
Ambient Temperature ◽  
Ocean Acidification ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Standing Stock ◽  
Co2 Concentration ◽  
Natural Seawater ◽  
Element Cycling ◽  
Coastal Phytoplankton

An in situ mesocosm experiment was performed to investigate the combined effects of ocean acidification and warming on the coastal phytoplankton standing stock and species composition of a eutrophic coastal area in the temperate-subtropical region. Experimental treatments of natural seawater included three CO2 and two temperature conditions (present control: ~400 μatm CO2 and ambient temperature, acidification conditions: ~900 μatm CO2 and ambient temperature, and greenhouse conditions: ~900 μatm CO2 and ambient temperature +3 °C). We found that increased CO2 concentration benefited the growth of small autotrophic phytoplankton groups: picophytoplankton (PP), autotrophic nanoflagellates (ANF), and small chain-forming diatoms (DT). However, in the greenhouse conditions, ANF and DT abundances were lower compared with those in the acidification conditions. The proliferation of small autotrophic phytoplankton in future oceanic conditions (acidification and greenhouse) also increased the abundance of heterotrophic dinoflagellates (HDF). These responses suggest that a combination of acidification and warming will not only increase the small autotrophic phytoplankton standing stock but, also, lead to a shift in the diatom and dinoflagellate species composition, with potential biogeochemical element cycling feedback and an increased frequency and intensity of harmful algal blooms.

scholarly journals The challenges of a small population exposed to multiple anthropogenic stressors and a changing climate: the St. Lawrence Estuary beluga

2021 ◽  
Vol 40 ◽  
Author(s):  
Véronique Lesage
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Extinction Risk ◽  
Small Population ◽  
Ecosystem Structure ◽  
Toxic Substances ◽  
Natal Philopatry ◽  
Lawrence Estuary ◽  
Fat Reserves ◽  
St Lawrence Estuary

Until 2012, the St. Lawrence Estuary beluga population was considered stable with about 1100 individuals. An abnormally high number of calves reported dead that year triggered a population status reassessment. This review article summarizes the findings from this reassessment and various studies subsequent to it and provides an updated analysis of carcass recovery rates up to 2019. The 2013 review indicated a decreased incidence of cancer in adults, suggesting positive impacts from the regulation of toxic substances (e.g., PCBs and PAHs). However, the review also revealed that the population initiated a decline of ca. 1% per year in the early 2000s and had reached a size of ca. 900 individuals by 2012. This decline was accompanied by high inter-annual variability in calf survival and pregnancy rates and by more frequent peripartum complications among dead females. The change in population dynamics coincided with a shift in the St. Lawrence ecosystem structure and warmer environmental conditions, suggesting a link through effects on reproductive success and adult female body condition. This was supported by the continued high calf mortality after 2012 and a documented decline of fat reserves in beluga blubber from 1998 to 2016. Other factors, such as the exposure to chronic vessel noise, increasing whale-watching activities, high contaminant levels and episodic harmful algal blooms, may also be contributing to the long-term non-recovery and current decline of the population. The strong natal philopatry and complex social system of the beluga likely increase its vulnerability to extinction risk by limiting dispersal.

scholarly journals Auxotrophic interactions: a stabilizing attribute of aquatic microbial communities?

2020 ◽  
Vol 96 (11) ◽  
Author(s):  
Winifred M Johnson ◽  
Harriet Alexander ◽  
Raven L Bier ◽  
Dan R Miller ◽  
Mario E Muscarella ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Theoretical Work ◽  
Microbial Interactions ◽  
Ecosystem Structure ◽  
Community Members ◽  
Aquatic Microorganisms ◽  
The Stability

ABSTRACT Auxotrophy, or an organism's requirement for an exogenous source of an organic molecule, is widespread throughout species and ecosystems. Auxotrophy can result in obligate interactions between organisms, influencing ecosystem structure and community composition. We explore how auxotrophy-induced interactions between aquatic microorganisms affect microbial community structure and stability. While some studies have documented auxotrophy in aquatic microorganisms, these studies are not widespread, and we therefore do not know the full extent of auxotrophic interactions in aquatic environments. Current theoretical and experimental work suggests that auxotrophy links microbial community members through a complex web of metabolic dependencies. We discuss the proposed ways in which auxotrophy may enhance or undermine the stability of aquatic microbial communities, highlighting areas where our limited understanding of these interactions prevents us from being able to predict the ecological implications of auxotrophy. Finally, we examine an example of auxotrophy in harmful algal blooms to place this often theoretical discussion in a field context where auxotrophy may have implications for the development and robustness of algal bloom communities. We seek to draw attention to the relationship between auxotrophy and community stability in an effort to encourage further field and theoretical work that explores the underlying principles of microbial interactions.

scholarly journals Diversity and Abundance of Phytoplankton in the Coastal Waters of South Sulawesi

2021 ◽  
Vol 28 (3) ◽  
pp. 199
Author(s):  
Hasriani Ayu Lestari ◽  
M. Farid Samawi ◽  
Ahmad Faizal ◽  
Abigail Mary Moore ◽  
Jamaluddin Jompa
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Inorganic Materials ◽  
Phytoplankton Abundance ◽  
Phytoplankton Diversity ◽  
South Sulawesi ◽  
Phytoplankton Communities

Phytoplankton are primary producers that can be used as seawater condition indicators. Certain phytoplankton can proliferate, causing harmful algal blooms (HABs). The coastal waters of South Sulawesi, Indonesia are under pressure from land-based processes and activities resulting in inputs of organic and inorganic materials. This study analysed phytoplankton diversity and abundance in coastal waters around South Sulawesi. Phytoplankton were sampled and seawater parameters (salinity, temperature, turbidity, pH, nitrate concentration) measured in-situ at six stations around seven major river estuaries in three seaways (Makassar Strait, Flores Sea, Gulf of Bone). Phytoplankton taxonomic composition, abundance and indices of diversity (H’), evenness (E), and dominance (D) were analysed. Phytoplankton from 31 species and three classes (Bacillariophyceae, Cyanophyceae, Dinophyceae) were identified. Phytoplankton abundance and community structure differed significantly between sites and seaways but were not significantly correlated with water quality parameters although Dinophyceae abundance correlated significantly with observed pollution levels. Phytoplankton abundance was strongly influenced by the Dinophyceae, especially Ceratium furca, a potential HAB species; Cyanophyceae had the strongest influence on species richness but least on community structure. C. furca abundance was strongly correlated negatively with species richness, H’ and E, and positively with D, indicating negative impacts of this species on phytoplankton communities.

Shellfish toxicity: human health implications of marine algal toxins

2010 ◽  
Vol 138 (7) ◽  
pp. 927-940 ◽  
Author(s):  
K. J. JAMES ◽  
B. CAREY ◽  
J. O'HALLORAN ◽  
F. N. A. M. van PELT ◽  
Z. ŠKRABÁKOVÁ
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Large Scale ◽  
Global Climate ◽  
Anthropogenic Activities ◽  
Detection Methods ◽  
Algal Toxins ◽  
Marine Transport ◽  
Ecological Changes ◽  
Marine Algal

SUMMARYFive major human toxic syndromes caused by the consumption of shellfish contaminated by algal toxins are presented. The increased risks to humans of shellfish toxicity from the prevalence of harmful algal blooms (HABs) may be a consequence of large-scale ecological changes from anthropogenic activities, especially increased eutrophication, marine transport and aquaculture, and global climate change. Improvements in toxin detection methods and increased toxin surveillance programmes are positive developments in limiting human exposure to shellfish toxins.

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