Macroalgal Blooms Research Articles

A Dynamic Energy Budget model for the macroalga Ulva lactuca

Macroalgal blooms in eutrophic coastal waters around the globe constitute a rising issue for ecosystems and economic activities. Sometimes leading to anoxic events, a better understanding of its growth dynamics is necessary to develop mitigation strategies and inform policies on nutrient runoff management. The development of a Dynamic Energy Budget (DEB) model for the sea lettuce, Ulva lactuca, provides a generic mechanistic description of energy and matter fluxes within the macroalgae and between macroalgae and the environment. Forcing variables consist of seawater temperature, light intensity, and seawater concentrations of dissolved carbon and nitrogen. The model includes a self-shading module for light reduction under heavy biomass and simulation outputs consist of (but are not limited to) total algae biomass, nutrient uptake (carbon and nitrogen), photosynthetic rate, and state of nutrient reserve. Model parameters were estimated using data-sets from the literature and laboratory experiments, then validated using an independent field study in two estuaries with contrasting nutrient loads that feed into Malpeque Bay, PEI (Canada). The validation step yielded accurate temporal predictions of sea lettuce biomass in both of these estuaries. These results indicate that the present mechanistic modelling approach for predicting sea lettuce dynamics captures salient patterns along a spectrum of nutrient loading and could therefore be of use for managing across diverse ecological conditions, which is particularly relevant for a widespread species like Ulva lactuca.

Complete chloroplast genome of Ulva pertusa, one of the causal species of green macroalgal blooms in the coastal waters of Qinhuangdao, China

Since 2015, macroalgae blooms have appeared along the Qinhuangdao coast of the Bohai Sea in China and they have recurred annually during the months of April to September. One of the causal species that results in the macroalgal blooms, Ulva pertusa, has been detrimental to the environment and ecosystem along the coast of the Qinhuangdao, China. In the present study, we sequenced the chloroplast genome of U. pertusa for the first time (GenBank accession number MN853875) and found that the annular genome comprised 104,380 base pairs, including 71 protein-coding genes, 26 tRNAs, and 2 rRNAs. We then constructed a phylogenetic tree of U. pertusa and 17 other species based on core genes, which showed that U. pertusa is the closest sister species of U. fasciata.

The complete mitochondrial genome sequence of Bryopsis plumosa

In 2015, a novel macroalgae began to bloom in Qinhuangdao on the coast of the Bohai Sea, Northern China. Bryopsis plumosa, a green macroalga, is one of the causal species of the macroalgae blooms, which have severely affected the environment and ecosystem on the coast of Qinhuangdao. In the present study, we sequenced the mitochondrial genome of B. plumosa for the first time (GenBank accession number MN853874). It was found that the ring-shaped genome was made up of 110,912 base pairs, including 29 protein-coding genes, 23 tRNAs, and 2 rRNAs. Phylogenetic analysis showed B. plumosa had close genetic relationships with algae Ulva prolifera, Ulva linza, and Ulva flexuosa. The present data will provide important information on the phylogenetics and molecular evolution of Bryopsis species.

Beneficios de los florecimientos macroalgales para la producción de biofertilizantes

En el presente ensayo se propone una alternativa para la producción de biofertilizantes a partir del aprovechamiento de los florecimientos macroalgales que se están suscitando en las lagunas costeras de Sinaloa. Las comunidades aledañas a las costas pueden obtener un beneficio económico al cosechar adecuadamente parte de la biomasa resultante de dichos florecimientos. La biomasa macroalgal extraída podría ser usada para la producción de biofertilizantes, con los siguientes beneficios: a) mitigar el daño ecológico provocado por los florecimientos macroalgales a los ecosistemas costeros eutrofizados; b) el uso de fertilizantes orgánicos en campos agrícolas permite reciclar N y P, evitando así, la aplicación de mas fertilizantes sintéticos, los cuales son los principales responsables de los florecimientos macroalgales; c) los biofertilizantes a base de macroalgas además de contener, N y P, contienen un conjunto de micronutrientes y sustancias con el potencial de beneficiar a los cultivos y mejorar los suelos; d) se contribuye al secuestro de carbono y a la reducción de gases de efecto invernadero en la atmósfera; y e) beneficios económicos en el aprovechamiento de una materia prima, hoy en día, de bajo valor o sin valor comercial. Tales biofertilizantes se utilizarían para producir frutos y vegetales de los denominados orgánicos, los cuales tienen una alta plusvalía y su demanda va en aumento en México y en el mundo. Esta es una alternativa enfocada en la producción de biofertilizantes para su utilización en la agricultura orgánica y producción de frutos de alto valor económico, los cuales pueden ser acreditados como orgánicos y al mismo tiempo, contribuir al mejoramiento de los suelos y del estado de salud de los ecosistemas costeros.

Implications of macroalgae blooms to the spatial structure of seagrass seascapes: The case of the Anadyomene spp. (Chlorophyta) bloom in Biscayne Bay, Florida

Macroalgal blooms are becoming an increasing problem in coastal regions worldwide and have been associated with a widespread decline of seagrass habitats. It is critical to measure macroalgal bloom (MB) impacts at broad spatial scales since seagrass seascape characteristics can influence feedback processes that regulate the resilience of seagrass ecosystems. We assessed the broad-scale spatial impacts of an MB formed by Anadyomene spp. on the seagrass seascapes in Biscayne Bay (Miami, US) using a multi-scale seascape approach. By integrating field and remote sensing data, our multi-scale approach showed significant reductions in seagrass foliage cover and a seascape structure transformation across the bloom extent. The landscape cover and patch extensiveness declined after the MB peak. Other spatial pattern metrics also showed that the seagrass seascape structure got fragmented. We demonstrated that a persistent MB could transform the structure of seagrass seascapes, hindering the resilience of seagrass habitats.

Green macroalgae blooms (Ulva spp.) influence trophic ecology of juvenile flatfish differently in sandy beach nurseries

Opportunistic green macroalgae blooms increasingly affect coastal areas worldwide. Understanding their impacts on organisms that use this zone, such as juvenile flatfish, is critical. By combining stable isotope data, digestive tract contents and community analyses of flatfish and their potential prey (benthic macroinvertebrates) from two North-East Atlantic sandy beaches (one impacted by blooms and one not), we detected similar and species-specific trophic changes among three co-occurring species (sand sole, plaice and turbot). Across flatfish species, juveniles displayed more opportunistic foraging behavior at the impacted site. Differently, plaice and sand sole relied more on the additional basal resource (Ulva spp.) than turbot. Finally, sand sole and turbot presented a stronger diet shift at the impacted site than plaice. We hypothesize that the species-specific response to the blooms are mostly driven by how the flatfish detect their prey (using visual and/or chemical cues) and when they forage (diurnal or nocturnal foraging).

Assessment of blooming Ulva macroalgae production potential in the Yellow Sea, China

ABSTRACTSince 2007, large-scale blooms have periodically broken out in the Yellow Sea, leading to serious economic and ecological problems in the surrounding coastal environments. Previous studies reported that the blooms originated in the Rudong oceanic area of the southern Yellow Sea and drifted almost 400 km into the Qingdao oceanic area of the northern Yellow Sea. In this study, chlorophyll concentrations, chlorophyll fluorescence, growth rates, and reproductive characteristics of floating Ulva prolifera collected along the Yellow Sea coast were assessed. The results revealed that these four physiological parameters in the Rudong area at the bloom source were considerably higher (2.02 mg/g, 0.68, 28.49% d−1, and 4 × 107, respectively) than in the Qingdao area (0.34 mg/g, 0.31, 5.23% d−1, and 0.67 × 107, respectively). However, the abundance of microscopic propagules of Ulva in the Qingdao area (3980 ind/l) was significantly higher than that in the Rudong area (667 ind/l). These findings help increase our understanding of the formation of the world’s largest Ulva macroalgal blooms.

Automatic Remote Sensing Detection of Floating Macroalgae in the Yellow and East China Seas Using Extreme Learning Machine

Liang, X.-J.; Qin, P.; Xiao, Y.-F.; Kim, K.-Y.; Liu, R.-J.; Chen, X.-Y., and Wang, Q,-B., 2019. Automatic remote sensing detection of floating macroalgae in the yellow and east china seas using extreme learning machine. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Remote Sensing and Geoscience Information Systems of Coastal Environments. Journal of Coastal Research, Special Issue No. 90, pp.272-281. Coconut Creek (Florida), ISSN 0749-0208.In the past 10 years, floating macroalgae blooms have occurred repeatedly in the Yellow Sea. For the purpose of disaster prevention and mitigation, it is very important to monitor floating macroalgae blooms using satellite imagery. The traditional macroalgae remote sensing detection methods based on the vegetation indices are very sensitive to the threshold value which is affected by many factors in the complex atmospheric–oceanic environment. The threshold has obvious temporal and spatial variations, and is difficult to determine accurately. The expert experience is required to assist the value of threshold which leads to the low automation of detection. Aiming at this problem, this study introduces an Extreme Learning Machine (ELM) into the field of macroalgae remote sensing detection. Taking the four-bands GF-1 WFV optical images with 16-m resolution as an example, an automatic remote sensing detection model of macroalgae is constructed. The evaluation based on independent data shows that the accuarcy of this method is up to 86 %. The method is not disturbed by thin clouds, sun glint, high-turbidity water, and other factors. In addition, no manual intervention is required which suggests that the proposed method has strong potential of automated detection for the floating macroalgae blooms.

Can scientists put Sargassum to work?

In the North Atlantic, there’s a region called a floating rain forest because of its incredible biodiversity. Known as the Sargasso Sea, the area takes its name from large mats of brown algae—Sargassum natans and Sargassum fluitans—that provide shelter, food, and breeding ground for fish, shrimps, birds, turtles, and crabs. But while the seaweed is a sanctuary in this place, it has become a scourge in another. Sargassum wasn’t a regular sight outside its native arena in the Sargasso Sea until 2011. That year, enormous mats of the algae started brewing farther south, in the central Atlantic, eventually washing onto beaches on the eastern and southern coasts of many Caribbean islands. By 2018, the mats had grown into the largest macroalgae bloom in recorded history, an 8,850 km long mass extending from the central Atlantic and Caribbean Sea to West Africa and the Gulf of Mexico. Chunks of Sargassum, circulated

A spatially aggressive peyssonnelid algal crust (PAC) threatens shallow coral reefs in St. John, US Virgin Islands

In recent decades, many Caribbean reefs have experienced large declines in abundance of scleractinian corals, and blooms of fleshy macroalgae have often accompanied these trends. In 2010 a new macroalgal threat emerged in Lac Bay, Bonaire, where peyssonnelid algal crusts (PAC) rapidly spread in shallow water and overgrew corals and sponges. Similar growths have been reported in Puerto Rico and the Virgin Islands, and here, we describe the spread of PAC on the shallow reefs of St. John, US Virgin Islands, ~ 760 km northeast of Bonaire. In 2015, PAC covered 0.2–20.6% of hard benthic surfaces at ≤ 7 m depth. By August 2017, at the same sites, PAC had increased to 3.2–61.0% cover, at 5 m depth at 10 other sites along 5 km of shore, it covered 1.4–61.6% of reef surfaces, and at 9 m depth at five sites, it covered 0.8–41.0% of reef surfaces. At 5 m depth in August 2017, scleractinians and octocorals were frequently contacting PAC (42–47% of colonies), and more scleractinians (74%) than octocorals (39%) were overgrown by PAC. Following surveys in August 2017, St. John was hit by two Category 5 hurricanes, yet the shore-wide mean cover of PAC at 5 m depth was only reduced from 26 to 23%. Our results suggest PAC is poised to cause significant ecological change on the reefs of St. John and potentially will promote a community shift favoring octocorals over scleractinians. PAC constitutes an emerging regional threat on shallow Caribbean reefs to which researchers and resource managers will need to quickly respond.

Low-temperature catalyst based Hydrothermal liquefaction of harmful Macroalgal blooms, and aqueous phase nutrient recycling by microalgae

The present study investigates the hydrothermal liquefaction (HTL) of harmful green macroalgal blooms at a temperature of 270 °C with, and without a catalyst with a holding time of 45 min. The effect of different catalysts on the HTL product yield was also studied. Two separation methods were used for recovering the biocrude oil yield from the solid phase. On comparision with other catalyst, Na2CO3 was found to produce higher yiled of bio-oil. The total bio-oil yield was 20.10% with Na2CO3, 18.74% with TiO2, 17.37% with CaO, and 14.6% without a catalyst. The aqueous phase was analyzed for TOC, COD, TN, and TP to determine the nutrient enrichment of water phase for microalgae cultivation. Growth of four microalgae strains viz., Chlorella Minutissima, Chlorella sorokiniana UUIND6, Chlorella singularis UUIND5 and Scenedesmus abundans in the aqueous phase were studied, and compared with a standard growth medium. The results indicate that harmful macroalgal blooms are a suitable feedstock for HTL, and its aqueous phase offers a promising nutrient source for microalgae.

The great Atlantic Sargassum belt.

Pelagic Sargassum is abundant in the Sargasso Sea, but a recurrent great Atlantic Sargassum belt (GASB) has been observed in satellite imagery since 2011, often extending from West Africa to the Gulf of Mexico. In June 2018, the 8850-kilometer GASB contained >20 million metric tons of Sargassum biomass. The spatial distribution of the GASB is mostly driven by ocean circulation. The bloom of 2011 might be a result of Amazon River discharge in previous years, but recent increases and interannual variability after 2011 appear to be driven by upwelling off West Africa during boreal winter and by Amazon River discharge during spring and summer, indicating a possible regime shift and raising the possibility that recurrent blooms in the tropical Atlantic and Caribbean Sea may become the new norm.

The biggest bloom

Marine Ecology![Figure][1] Underwater photograph taken near Key Largo, Florida, of a Sargassum mat from below CREDIT: CHRIS GUG/ALAMY STOCK PHOTO Floating mats of Sargassum seaweed in the center of the North Atlantic were first reported by Christopher Columbus in the 15th century. These mats, although abundant, have until recently been limited and discontinuous. However, Wang et al. report that, since 2011, the mats have increased in density and aerial extent to generate a 8850-kilometer-long belt that extends from West Africa to the Caribbean Sea and Gulf of Mexico (see the Perspective by Gower and King). This represents the world's largest macroalgal bloom. Such recurrent blooms may become the new normal. Science , this issue p. [83][2]; see also p. [27][3] [1]: pending:yes [2]: /lookup/doi/10.1126/science.aaw7912 [3]: /lookup/doi/10.1126/science.aay0989

Wadden Sea Eutrophication: Long-Term Trends and Regional Differences

The Wadden Sea is a shallow intertidal coastal sea, largely protected by barrier islands and fringing the North Sea coasts of The Netherlands, Germany and Denmark. It is subject to influences from both the North Sea and major European rivers. Nutrient enrichment from these rivers since the 1950s has impacted the Wadden Sea ecology including loss of seagrass, increased phytoplankton blooms and increased green macroalgae blooms. Rivers are the major source of nutrients causing Wadden Sea eutrophication. The nutrient input of the major rivers impacting the Wadden Sea reached a maximum during the 1980s and decreased at an average pace of about 2.5 % per year for total Nitrogen (TN) and about 5 % per year for total Phosphorus (TP), leading to decreasing nutrient levels but also increasing N/P ratios. During the past decade, the lowest nutrient inputs since 1977 were observed but these declining trends are levelling out for TP. Phytoplankton biomass (measured as chlorophyll a) in the Wadden Sea has decreased since the 1980s and presently reached a comparatively low level. In tidal inlet stations with a long-term monitoring, summer phytoplankton levels correlate with riverine TN and TP loads but stations located closer to the coast behave in a more complex manner. Regional differences are observed, with highest chlorophyll a levels in the southern Wadden Sea and lowest levels in the northern Wadden Sea. Model data support the hypothesis that the higher eutrophication levels in the southern Wadden Sea are linked to a more intense coastward accumulation of organic matter produced in the North Sea.

Monitoring seaweed aquaculture in the Yellow Sea with multiple sensors for managing the disaster of macroalgal blooms

Multi-sensor remote sensing is a critical part of the surveillance of coastal ocean for hazard management. The world's largest green macroalgae blooms (green tide) in the Yellow Sea since 2007 are caused by the macroalgae of Ulva, which are disposed as biofoulings into sea water when workers recycle seaweed (Porphyra) farming facilities. We traced the development processes of seaweed cultivation in which area since 2000 and the variation in macroalgal blooms since 2007 through multi-sensors (satellite, Unmanned Aerial Vehicle, and ground spectroradiometer) remote sensing in this study. We found that the sudden occurrence of large-scale green tide in 2007 and the increasing trend since that year were caused by the seaweed aquaculture in a specific mode at specific locations. A numerical simulation and satellite observations on the relationship between the timing of recycling seaweed facilities and the volume of green tide suggest that the green tide is manageable. Adoption of multi-sensor, multi-scale, and multi-temporal observations, translocating seaweed farming sites, and changing the cultivation mode are deemed as key tools for controlling the green tide and sustaining the seaweed aquaculture.

EU Project of Life Programme “Algae Service for Life” Creates Tools for Ecological Service to Mitigate Cyanobacteria and Macroalgae Blooms in Freshwater Ecosystems

AbstractEU international project of LIFE programme “Algae Service for LIFE” seeks to promote best practices in ecological service and development of circular economy. The goal of the project is to demonstrate integrated efficient management of nutrients and nuisance algal blooms at the catchment scale by harvesting cyanobacteria scums and macroalgae mats in various types of water bodies (rivers, lakes and estuarine lagoon). Also, it seeks to raise awareness of the national and local authorities, business community and society on the environmental, water quality and health hazard issues. The paper provides the idea of applying ecological measures to control algal blooms. Thus, issues related to the causes and mechanisms of eutrophication in inland freshwaters as well as to consequences such as algal blooms are highlighted. The measures proposed in the project are briefly discussed in the light of European Union directives.

An increase in new Sargassum (Phaeophyceae) blooms along the coast of the East China Sea and Yellow Sea

ABSTRACTNew macroalgal blooms caused by the genus Sargassum have been occurring along the coast of China. In particular, in 2017, Sargassum blooms covered up to 188 km2 and drifted into the offshore region of Jiangsu Province, the traditional area for Pyropia aquaculture. This resulted in an enormous loss of production of Pyropia. This study was designed to identify the species composition, phylogenetic relationships, and possible origin of the free-floating Sargassum populations in the Yellow Sea and East China Sea. Results from morphological observations and molecular identification showed that Sargassum horneri was the only species comprising the blooms. Based on further satellite remote sensing analysis, the suspected origin of the blooms was the coastal area of Zhejiang Province, where S. horneri is widely distributed. This study increases our understanding of the importance of controlling the spread of macroalgae blooms.

Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 616:37-49 (2019) - DOI: https://doi.org/10.3354/meps12927 Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land Sandra Walløe Thorsen*, Erik Kristensen, Thomas Valdemarsen, Mogens R. Flindt, Cintia Organo Quintana, Marianne Holmer Department of Biology, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark *Corresponding author: sandrawt@biology.sdu.dk ABSTRACT: Managed realignment by deliberate flooding of coastal areas is an adaptation to sea level rise but may risk enriching the coastal zone with nutrients when seawater floods agricultural soil. This study focuses on the early development of macroalgae and their sources of nitrogen (N) in Gyldensteen Coastal Lagoon, Denmark. The lagoon was claimed for agricultural purposes in 1871 and reflooded by managed realignment 143 yr later (2014). Our hypotheses were: (1) that nutrients of agricultural origin from the newly flooded soil initiate opportunistic macroalgal blooms; and (2) that the isotopic composition of green algae rapidly reflects the origin of nutrient sources. We monitored macroalgal cover and conducted stable isotope (δ15N) analyses to assess the origin of N sources. Intense green macroalgal blooms occurred during the first summer after flooding and diminished in the 2 following years as a result of rapid water exchange. Low δ15N in macroalgae in the first year (mean ± SE, 4.2 ± 0.3‰) increased significantly in the next year (8.0 ± 0.1‰). A laboratory experiment tested the δ15N response of opportunistic green macroalgae (Ulva spp.) exposed to organic manure and synthetic inorganic fertilizers. Higher δ15N (11.1 ± 0.1‰) characterized manure-treated algae compared to fertilizer-treated algae (2.7 ± 0.2‰). Based on these field and laboratory results, we accept both hypotheses and conclude that the major N source supporting macroalgal growth in 2014 was derived from synthetic fertilizers; however, rapid tidal flushing during the following years resulted in nutrient limitation and lower macroalgal growth. KEY WORDS: Nitrogen · Macroalgal bloom · Nutrient sources · Sea level rise · Coastal realignment · Gyldensteen Coastal Lagoon Full text in pdf format PreviousNextCite this article as: Thorsen SW, Kristensen E, Valdemarsen T, Flindt MR, Quintana CO, Holmer M (2019) Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land. Mar Ecol Prog Ser 616:37-49. https://doi.org/10.3354/meps12927 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 616. Online publication date: May 09, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Temporal variability in zooplankton community in the western Yellow Sea and its possible links to green tides.

Large-scale macro-algal blooms of Ulva prolifera (also called green tides) have appeared each summer since 2008 in the western Yellow Sea. In this study, we investigated the temporal variability in zooplankton community in the western Yellow Sea and its possible links to green tides using data from a long-term plankton survey off the coast of Qingdao, China. Environmental conditions observed in the study area during the green tide period (GTP: June–August, 2008–2013) were compared to the non-green tide period (NGTP: June–August, 2005–2007), to support the contention that variations observed in zooplankton community may be attributed to the green tides, as opposed to natural climatic or environmental variations. Zooplankton assemblage structure observed during the GTP was then compared to the NGTP. Significant variations were detected both in zooplankton abundance and assemblage structure between the two defined periods. The abundance of zooplankton, mainly copepods, was significantly decreased during the GTP. Meanwhile, the relative abundance of copepods decreased by approximately 10% and that of gelatinous zooplankton, including appendicularians, chaetognaths, and medusae, almost doubled (ca. increased by 6.4%). The dominant species of meroplankton completely changed, specifically, polychaeta, and echinoderm larvae were more dominant than decapod and bivalve larvae. With regard to zooplankton size structure, the NGTP showed a higher size diversity with more small-sized organisms, while the GTP showed a lower size diversity in the community. According to general linear models, the interannual variation in summer zooplankton abundance was significantly correlated with green tides. These results indicate that the temporal changes in zooplankton community may have a close link to the green tides.

Coral Skeleton \u03b415N as a Tracer of Historic Nutrient Loading to a Coral Reef in Maui, Hawaii

Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δ15N) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources. Our results show a dramatic increase in coral δ15N values after 1995, corresponding with the implementation of biological nutrient removal at the nearby Lahaina Wastewater Reclamation Facility (LWRF). High δ15N values are known to be strongly indicative of denitrification and sewage effluent, corroborating a previously suggested link between local wastewater injection and degradation of the reef environment. This record demonstrates the power of coral skeletal δ15N as a tool for evaluating nutrient dynamics within coral reef environments.