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

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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On the potential causes of the recent Pelagic Sargassum blooms events in the tropical North Atlantic Ocean

10.5194/bg-2017-346 ◽

2017 ◽

Cited By ~ 5

Author(s):

Sandrine Djakouré ◽

Moacyr Araujo ◽

Aubains Hounsou-Gbo ◽

Carlos Noriega ◽

Bernard Bourlès

Keyword(s):

Atlantic Ocean ◽

North Atlantic Ocean ◽

Large Mass ◽

Recirculation Region ◽

Brown Macroalgae ◽

The West ◽

The North ◽

Tropical North Atlantic ◽

Equatorial Upwelling ◽

Favorable Conditions

Abstract. Since 2011, unprecedented and repetitive blooms and large mass strandings of the floating brown macroalgæ, Sargassum natans and Sargassum fluitans have been reported along the West Indies, the Caribbean, the Brazilian and the West Africa coasts. Recent studies have highlighted a new tank of Sargassum: the North Equatorial Recirculation Region of the Atlantic Ocean. This region is located off the northeast of Brazil, approximately between the equator and 10° N and from 50° W to 25° W. The potential causes of these recent blooms and mass strandings are still poorly understood. Observational datasets and modelling outputs involving hydrological parameters and climate events are examined focusing on their potential feedback on the observed blooms and mass strandings. The results show that combined conditions have been in favor of these recent changes. High anomalously unprecedented positive sea surface temperature observed in the tropical Atlantic in 2010–2011 could have induced favorable temperature conditions for Sargassum blooms. These favorable conditions were then fed by additional continental nutrients inputs, principally from the Amazon River. These continental nutrients load are the consequences of deforestation, agroindustrial and urban activities in the Amazonian forest. The results also suggest that subsurface intake of nutrients from the equatorial upwelling could also contribute to the blooms of the Sargassum seaweed in the Atlantic Ocean but further studies are needed to confirm these additional inputs.

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Challenges in modeling spatiotemporally varying phytoplankton blooms in the Northwestern Arabian Sea and Gulf of Oman

Biogeosciences ◽

10.5194/bg-13-1049-2016 ◽

2016 ◽

Vol 13 (4) ◽

pp. 1049-1069 ◽

Cited By ~ 5

Author(s):

S. Sedigh Marvasti ◽

A. Gnanadesikan ◽

A. A. Bidokhti ◽

J. P. Dunne ◽

S. Ghader

Keyword(s):

Interannual Variability ◽

Annual Cycle ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Arabian Sea ◽

Regional Scale ◽

Phytoplankton Productivity ◽

Gulf Of Oman ◽

The North ◽

The Persian Gulf

Abstract. Recent years have shown an increase in harmful algal blooms in the Northwest Arabian Sea and Gulf of Oman, raising the question of whether climate change will accelerate this trend. This has led us to examine whether the Earth System Models used to simulate phytoplankton productivity accurately capture bloom dynamics in this region – both in terms of the annual cycle and interannual variability. Satellite data (SeaWIFS ocean color) show two climatological blooms in this region, a wintertime bloom peaking in February and a summertime bloom peaking in September. On a regional scale, interannual variability of the wintertime bloom is dominated by cyclonic eddies which vary in location from one year to another. Two coarse (1°) models with the relatively complex biogeochemistry (TOPAZ) capture the annual cycle but neither eddies nor the interannual variability. An eddy-resolving model (GFDL CM2.6) with a simpler biogeochemistry (miniBLING) displays larger interannual variability, but overestimates the wintertime bloom and captures eddy-bloom coupling in the south but not in the north. The models fail to capture both the magnitude of the wintertime bloom and its modulation by eddies in part because of their failure to capture the observed sharp thermocline and/or nutricline in this region. When CM2.6 is able to capture such features in the Southern part of the basin, eddies modulate diffusive nutrient supply to the surface (a mechanism not previously emphasized in the literature). For the model to simulate the observed wintertime blooms within cyclones, it will be necessary to represent this relatively unusual nutrient structure as well as the cyclonic eddies. This is a challenge in the Northern Arabian Sea as it requires capturing the details of the outflow from the Persian Gulf – something that is poorly done in global models.

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

Journal of Plankton Research ◽

10.1093/plankt/fbaa011 ◽

2020 ◽

Vol 42 (2) ◽

pp. 119-134 ◽

Cited By ~ 1

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.

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The North Atlantic Oscillation and the Arctic Oscillation favour harmful algal blooms in SW Europe

Harmful Algae ◽

10.1016/j.hal.2014.07.008 ◽

2014 ◽

Vol 39 ◽

pp. 121-126 ◽

Cited By ~ 8

Author(s):

José C. Báez ◽

Raimundo Real ◽

Victoria López-Rodas ◽

Eduardo Costas ◽

A. Enrique Salvo ◽

...

Keyword(s):

North Atlantic Oscillation ◽

North Atlantic ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Arctic Oscillation ◽

The Arctic ◽

The North ◽

The North Atlantic ◽

The Arctic Oscillation ◽

The North Atlantic Oscillation

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

10.20944/preprints201804.0316.v1 ◽

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.

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Climate change and harmful algal blooms in the North Sea

Acta Oecologica ◽

10.1016/s1146-609x(03)00009-2 ◽

2003 ◽

Vol 24 ◽

pp. S139-S144 ◽

Cited By ~ 81

Author(s):

Louis Peperzak

Keyword(s):

Climate Change ◽

North Sea ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

The North ◽

The North Sea

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Harmful algal blooms in the Eastern North Atlantic Ocean

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1715499114 ◽

2017 ◽

Vol 114 (46) ◽

pp. E9763-E9764 ◽

Cited By ~ 7

Author(s):

Paul Dees ◽

Eileen Bresnan ◽

Andrew C. Dale ◽

Martin Edwards ◽

David Johns ◽

...

Keyword(s):

Atlantic Ocean ◽

North Atlantic ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

North Atlantic Ocean ◽

Eastern North Atlantic ◽

Eastern North Atlantic Ocean

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Ocean warming since 1982 has expanded the niche of toxic algal blooms in the North Atlantic and North Pacific oceans

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1619575114 ◽

2017 ◽

Vol 114 (19) ◽

pp. 4975-4980 ◽

Cited By ~ 147

Author(s):

Christopher J. Gobler ◽

Owen M. Doherty ◽

Theresa K. Hattenrath-Lehmann ◽

Andrew W. Griffith ◽

Yoonja Kang ◽

...

Keyword(s):

Growth Rates ◽

North Pacific ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Global Ocean ◽

Potential Growth ◽

Alexandrium Fundyense ◽

The North ◽

Temperature Records ◽

Dependent Growth

Global ocean temperatures are rising, yet the impacts of such changes on harmful algal blooms (HABs) are not fully understood. Here we used high-resolution sea-surface temperature records (1982 to 2016) and temperature-dependent growth rates of two algae that produce potent biotoxins, Alexandrium fundyense and Dinophysis acuminata, to evaluate recent changes in these HABs. For both species, potential mean annual growth rates and duration of bloom seasons significantly increased within many coastal Atlantic regions between 40°N and 60°N, where incidents of these HABs have emerged and expanded in recent decades. Widespread trends were less evident across the North Pacific, although regions were identified across the Salish Sea and along the Alaskan coastline where blooms have recently emerged, and there have been significant increases in the potential growth rates and duration of these HAB events. We conclude that increasing ocean temperature is an important factor facilitating the intensification of these, and likely other, HABs and thus contributes to an expanding human health threat.

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Optical Detection of Harmful Algal Blooms in the Belgian Coastal Zone: A Cautionary Tale of Chlorophyll c3

Frontiers in Marine Science ◽

10.3389/fmars.2021.770340 ◽

2021 ◽

Vol 8 ◽

Author(s):

Alexandre Castagna ◽

Heidi Dierssen ◽

Emanuele Organelli ◽

Margarita Bogorad ◽

Jonas Mortelmans ◽

...

Keyword(s):

North Sea ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Optical Detection ◽

Biomass Concentration ◽

Optical Signal ◽

Optical Data ◽

Optical Signals ◽

Southern North Sea ◽

The North

Phaeocystis globosa is a nuisance haptophyte species that forms annual blooms in the southern North Sea and other coastal waters. At high biomass concentration, these are considered harmful algal blooms due to their deleterious impact on the local ecosystems and economy, and are considered an indicator for eutrophication. In the last two decades, methods have been developed for the optical detection and quantification of these blooms, with potential applications for autonomous in situ or remote observations. However, recent experimental evidence suggests that the interpretation of the optical signal and its exclusive association with P. globosa may not be accurate. In the North Sea, blooms of P. globosa are synchronous with those of the diatom Pseudo-nitzschia delicatissima, another harmful bloom-forming species with similar pigmentation and optical signature. Here we combine new and published measurements of pigmentation composition and inherent optical properties from pure cultures of several algal and cyanobacterial groups, together with environmental spectroscopy data, to identify the pigments generating the optical signals captured by two established algorithms. We further evaluate the association of those pigments and optical signals with P. globosa. We found that the interpretation of the pigment(s) generating the optical signals were incorrect and that previous methods are not specific to P. globosa, even in the context of the phytoplankton assemblage of the southern North Sea. Additionally, we found that the optical and pigment signatures of Phaeocystis species are part of a broad pigmentation trend across unrelated taxonomic groups related to chlorophyll c3 presence, with important consequences for the interpretation of pigment and optical data. We then develop and evaluate an algorithm to detect this pigmentation pattern with minimal influence of co-occurring species and elaborate general recommendations for the future development of algorithms.

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

Oseanologi dan Limnologi di Indonesia ◽

10.14203/oldi.2021.v6i3.382 ◽

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

The Abundance of the Harmful Benthic Dinoflagellate in the Seagrass and Macroalgae Habitats on Pari Island, Thousand Islands, Indonesia. 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 Amphidinium, Coolia, Gambierdiscus, Ostreopsis, and Prorocentrum, 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. Gambierdiscus were found as the most abundant benthic dinoflagellate in seagrass habitats, while Prorocentrum 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 Ostreopsis, 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.

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