Harmful algal blooms as a sink for inorganic nutrients in a eutrophic estuary

2021 ◽  
Vol 663 ◽  
pp. 63-76
Author(s):  
DA Lemley ◽  
JB Adams ◽  
JL Largier
Keyword(s):  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Phytoplankton Biomass ◽  
Algal Blooms ◽  
Nutrient Dynamics ◽  
Nutrient Loading ◽  
Positive Association ◽  
Inorganic Nutrient ◽  
Study Objective ◽  
Hydrological Variability

Phytoplankton-mediated nutrient fluxes typically provide only pulsed relief to adjacent coastal waters during the productive period, with nutrient export increasing in the absence of substantial phytoplankton biomass. On the warm temperate coastline of South Africa, the Sundays Estuary is characterised by highly regulated freshwater inflow patterns, nutrient-enriched conditions, and resident harmful algal blooms (HABs). Given these attributes, the study objective was to investigate the effect of these phytoplankton blooms on fluvial inorganic nutrient dynamics. To assess uptake, we analysed inorganic nutrient (phosphate, ammonium, NOx) and phytoplankton concentrations in relation to salinity using data from 17 surveys. Property-salinity mixing diagrams and statistical analyses indicated a positive association between increasing phytoplankton biomass and decreasing NOx flux (p < 0.001), and to a lesser degree phosphate flux (p = 0.22), along the gradient from low-salinity inner estuary to high salinity outer estuary. High biomass HAB accumulations of Heterosigma akashiwo (>100 µg chl a l-1) represent significant removal of available NOx (~100%) and phosphate (>75%) during warmer conditions (>20°C). These events, together with continuous inorganic nutrient uptake during less severe bloom conditions, remove a substantial portion of annual NOx and phosphate loads (36.5 and 36.4% flux, respectively). Although this buffers inorganic nutrient loading to adjacent coastal waters, it also represents an emerging legacy pollution issue in the form of a benthic accumulation of organic material in bottom waters subject to recurrent hypoxia. Future management efforts should adopt an ecosystem-based approach centred around simultaneous restoration of hydrological variability and dual nutrient reduction strategies (N and P).

scholarly journals Global change and eutrophication of coastal waters

2009 ◽  
Vol 66 (7) ◽  
pp. 1528-1537 ◽  
Author(s):  
Nancy N. Rabalais ◽  
R. Eugene Turner ◽  
Robert J. Díaz ◽  
Dubravko Justić
Keyword(s):  
Water Quality ◽  
Global Change ◽  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Nutrient Loading ◽  
Global Climate ◽  
Oxygen Depletion ◽  
Negative Consequences ◽  
Storm Activity

Abstract Rabalais, N. N., Turner, R. E., Díaz, R. J., and Justić, D. 2009. Global change and eutrophication of coastal waters. – ICES Journal of Marine Science, 66: 1528–1537. The cumulative effects of global change, including climate change, increased population, and more intense industrialization and agribusiness, will likely continue and intensify the course of eutrophication in estuarine and coastal waters. As a result, the symptoms of eutrophication, such as noxious and harmful algal blooms, reduced water quality, loss of habitat and natural resources, and severity of hypoxia (oxygen depletion) and its extent in estuaries and coastal waters will increase. Global climate changes will likely result in higher water temperatures, stronger stratification, and increased inflows of freshwater and nutrients to coastal waters in many areas of the globe. Both past experience and model forecasts suggest that these changes will result in enhanced primary production, higher phytoplankton and macroalgal standing stocks, and more frequent or severe hypoxia. The negative consequences of increased nutrient loading and stratification may be partly, but only temporarily, compensated by stronger or more frequent tropical storm activity in low and mid-latitudes. In anticipation of the negative effects of global change, nutrient loadings to coastal waters need to be reduced now, so that further water quality degradation is prevented.

scholarly journals Comparative analysis of full-length mitochondrial genomes of five Skeletonema species reveals conserved genome organization and recent speciation

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Shuya Liu ◽  
Yichao Wang ◽  
Qing Xu ◽  
Mengjia Zhang ◽  
Nansheng Chen
Keyword(s):  
Molecular Markers ◽  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Phylogenetic Analyses ◽  
Time Estimation ◽  
Single Species ◽  
Full Length ◽  
Comparative Genomic ◽  
Primary Producers

Abstract Background Skeletonema species are prominent primary producers, some of which can also cause massive harmful algal blooms (HABs) in coastal waters under specific environmental conditions. Nevertheless, genomic information of Skeletonema species is currently limited, hindering advanced research on their role as primary producers and as HAB species. Mitochondrial genome (mtDNA) has been extensively used as “super barcode” in the phylogenetic analyses and comparative genomic analyses. However, of the 21 accepted Skeletonema species, full-length mtDNAs are currently available only for a single species, S. marinoi. Results In this study, we constructed full-length mtDNAs for six strains of five Skeletonema species, including S. marinoi, S. tropicum, S. grevillei, S. pseudocostatum and S. costatum (with two strains), which were isolated from coastal waters in China. The mtDNAs of all of these Skeletonema species were compact with short intergenic regions, no introns, and no repeat regions. Comparative analyses of these Skeletonema mtDNAs revealed high conservation, with a few discrete regions of high variations, some of which could be used as molecular markers for distinguishing Skeletonema species and for tracking the biogeographic distribution of these species with high resolution and specificity. We estimated divergence times among these Skeletonema species using 34 mtDNAs genes with fossil data as calibration point in PAML, which revealed that the Skeletonema species formed the independent clade diverging from Thalassiosira species approximately 48.30 Mya. Conclusions The availability of mtDNAs of five Skeletonema species provided valuable reference sequences for further evolutionary studies including speciation time estimation and comparative genomic analysis among diatom species. Divergent regions could be used as molecular markers for tracking different Skeletonema species in the fields of coastal regions.

scholarly journals Action Plan for Monitoring, Mitigation and Management of Harmful Algal Blooms in the Coastal Waters of Oman

2007 ◽  
Vol 12 (2) ◽  
pp. 75
Author(s):  
A.Y.A AlKindi ◽  
H.M.H. Al-Ghelani ◽  
S. Amer ◽  
Y.K Al-Akhzami
Keyword(s):  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Red Tide ◽  
Action Plan ◽  
Rapid Response System ◽  
Gulf Of Oman ◽  
Trichodesmium Erythraeum ◽  
Response System ◽  
Adverse Impacts

The Gulf of Oman, an ecologically and economically rich ecosystem, is frequently impacted by occurrences of harmful algal blooms. Recent studies indicate an increase in the number of causative species and harmful impacts. Many red tide incidents in Oman have been found leading to hypoxia. The frequent bloom forming species here are Karenia selliformis, Nitzschia pungens, Prorocentrum arabianum and Trichodesmium erythraeum. We review work carried out in this area, and we propose here a Management Action Plan for not only an effective monitoring system for harmful algal blooms (HABs), but also mitigation of their adverse impacts and rapid response system.   

Dead Zones

2021 ◽  
Author(s):  
David L. Kirchman
Keyword(s):  
Cover Crops ◽  
Precision Agriculture ◽  
Coastal Waters ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Biological Diversity ◽  
Oxygen Depletion ◽  
Waterborne Diseases ◽  
Buffer Zones ◽  
Dead Zones

This book explores the many rivers, lakes, and oceans that are losing oxygen. Aquatic habitats with little dissolved oxygen are called dead zones because nothing can live there except some microbes. The number and size of dead zones are increasing worldwide. The book shows that oxygen loss causes fish kills, devastates bottom-dwelling biota, reduces biological diversity, and rearranges aquatic food webs. In the 19th century in rich countries and in poor regions today, dead zones are accompanied by waterborne diseases that kill thousands of people. The open oceans are losing oxygen because of climate change, whereas dead zones in coastal waters and seas are caused by excessive nutrients, which promote excessive growth of algae and eventually oxygen depletion. Work by Gene Turner and Nancy Rabalais demonstrated that nutrients in the Gulf of Mexico come from fertilizers used in the US Midwest, home to the most productive cropland in the world. Agriculture is also the biggest source of nutrients fuelling dead zones in the Baltic Sea and other coastal waters. Today, fertilizers contaminate drinking water and kick-start harmful algal blooms in local lakes and reservoirs. Nutrient pollution in some regions has declined because of buffer zones, cover crops, and precision agriculture, but more needs to be done. The book concludes by arguing that each of us can do our part by changing our diet; eating less, especially eating less red meat, would improve our health and the health of the environment. A better diet could reduce the amount of greenhouse gas emitted by agriculture and shrink dead zones worldwide.

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