Aquatic Microbial Ecology and Biogeochemistry: A Dual Perspective, 2016
Blooms of the toxic cyanobacterium, Lyngbya majuscula, were observed in Moreton Bay, Australia, b... more Blooms of the toxic cyanobacterium, Lyngbya majuscula, were observed in Moreton Bay, Australia, beginning in the late 1990s. These dense blooms led to significant human and ecosystem health impacts. Research on the causes of the bloom focused on nutrient interactions (e.g., nitrogen, phosphorus, and iron) and light availability, in particular, light quality. Light quality investigations reported here were instigated because of the abundance of humic-stained water runoff from the catchment that periodically washed into the primary bloom locations. Light quality experiments were conducted on L. majuscula in aquaria using spectral filters to simulate different light regimes. The most pronounced effect on L. majuscula pigment content and productivity rates was the colored water treatment that simulated the humic-stained runoff. Colored water stimulated pigment content (phycoerythrin and chlorophyll a) and productivity (14C uptake) compared with clear water, turbid water, and a combination of turbid/colored water treatments. Previous research identified the importance of humic compounds in making iron bioavailable to L. majuscula. These results, combined with previous studies of L. majuscula and nutrient interactions, were used to construct a conceptual model of the primary causes of L. majuscula blooms in Moreton Bay, Australia. This model is presented in a diagrammatic format to synthesize research results as to the causes of these cyanobacteria blooms. The Lyngbya majuscula model focuses on having sufficient nutrients, particularly bioavailable iron, in a light climate of colored water. This model for toxic cyanobacteria blooms of L. majuscula in Australia also has relevance in other parts of the world.
Abstract Blooms of Karenia brevis plague the West Florida Shelf (WFS) region in the Gulf of Mexic... more Abstract Blooms of Karenia brevis plague the West Florida Shelf (WFS) region in the Gulf of Mexico (GOM) where they exert harmful effects on aquatic biota and humans. Because productivity on the WFS is N limited, new N inputs into the region are thought to trigger blooms of K. brevis. Here we examine the potential for new N inputs via N2 fixation by Trichodesmium and other diazotrophic plankton to contribute to the N demand of K. brevis. Because of possible methodological biases, we also compared N2 fixation rates by cultured Trichodesmium using the 15N2 bubble addition method and the 15N2 saturated seawater. Both methods yielded identical results in 12 and 24 h incubations; however, there was more variability in rate estimates made using the bubble addition method. Pelagic N2 fixation rates by other planktonic diazotrophs ranged from 0 to 13.6 nmol N L−1 d−1, comparable to or higher than rates observed in oligotrophic gyres. These rates should be considered conservative estimates because they were made using the bubble addition method. Integrating over our study area, we estimate that new inputs of N to the WFS via N2 fixation are on the order of 0.011 Tmol N annually. Further, we measured directly the trophic transfer of recently fixed N2 to co-occurring plankton that included K. brevis and found that up to 47% of N2 fixed was transferred to non-diazotrophic plankton even in short (
... Large numbers of juvenile Macrosetella have also been found associated with Trichodesmium in ... more ... Large numbers of juvenile Macrosetella have also been found associated with Trichodesmium in waters off Japan (Tokioka & Bieri, 1966 ; Ohki ... the two dominant species of Trichodesmium, T thiebautii and T ery-thraeum by Macrosetella gracilis and Miracia effer-ata were also ...
O'Neil, JM, Albert, S., Osborne, N., Shaw, GR, Heil, CA, Mulholland, M. and Bronk, DA (2004)... more O'Neil, JM, Albert, S., Osborne, N., Shaw, GR, Heil, CA, Mulholland, M. and Bronk, DA (2004). Nitrogen acquisition by the toxic marine cyanobacterium Lyngbya majuscula from Moreton Bay Australia and Tampa Bay Florida. In: , Harmful Algae. XIth International Conference ...
... Brown and Boyd, 1982) and intoxication due to ingestion of sea-turtle meat and macroalgae epi... more ... Brown and Boyd, 1982) and intoxication due to ingestion of sea-turtle meat and macroalgae epiphytised by L. majuscula (Osborne et al ... wracks of decaying L. majuscula by local government for health and aesthetic reasons (Dennison and Abal, 1999 and O'Neil and Dennison ...
Limnol. Oceanogr., 51(5), 2006, 2484 E 2006, by the American Society of Limnology and Oceanograph... more Limnol. Oceanogr., 51(5), 2006, 2484 E 2006, by the American Society of Limnology and Oceanography, Inc. ... Erratum: Nitrogen fixation and release of fixed nitrogen by Trichodesmium spp. in the Gulf of Mexico ... There is an error in our paper published in L&O 51: ...
Summary Intensive sampling of the Maryland Coastal Bays in May and July of 2007 served to further... more Summary Intensive sampling of the Maryland Coastal Bays in May and July of 2007 served to further assess spatial patterns in nutrients, responses of biological indicators, seasons, land use, and nutrient cycling. Studies conducted in 2004 and 2006 had pinpointed the regions of St. Martin River and Johnsons Bay as areas of degraded water quality, high turbidity, increasing total nitrogen and phosphorus concentrations, high natural isotope abundance (δ15N), and low dissolved oxygen. Therefore the current study sought to ...
Aquatic Microbial Ecology and Biogeochemistry: A Dual Perspective, 2016
Blooms of the toxic cyanobacterium, Lyngbya majuscula, were observed in Moreton Bay, Australia, b... more Blooms of the toxic cyanobacterium, Lyngbya majuscula, were observed in Moreton Bay, Australia, beginning in the late 1990s. These dense blooms led to significant human and ecosystem health impacts. Research on the causes of the bloom focused on nutrient interactions (e.g., nitrogen, phosphorus, and iron) and light availability, in particular, light quality. Light quality investigations reported here were instigated because of the abundance of humic-stained water runoff from the catchment that periodically washed into the primary bloom locations. Light quality experiments were conducted on L. majuscula in aquaria using spectral filters to simulate different light regimes. The most pronounced effect on L. majuscula pigment content and productivity rates was the colored water treatment that simulated the humic-stained runoff. Colored water stimulated pigment content (phycoerythrin and chlorophyll a) and productivity (14C uptake) compared with clear water, turbid water, and a combination of turbid/colored water treatments. Previous research identified the importance of humic compounds in making iron bioavailable to L. majuscula. These results, combined with previous studies of L. majuscula and nutrient interactions, were used to construct a conceptual model of the primary causes of L. majuscula blooms in Moreton Bay, Australia. This model is presented in a diagrammatic format to synthesize research results as to the causes of these cyanobacteria blooms. The Lyngbya majuscula model focuses on having sufficient nutrients, particularly bioavailable iron, in a light climate of colored water. This model for toxic cyanobacteria blooms of L. majuscula in Australia also has relevance in other parts of the world.
Abstract Blooms of Karenia brevis plague the West Florida Shelf (WFS) region in the Gulf of Mexic... more Abstract Blooms of Karenia brevis plague the West Florida Shelf (WFS) region in the Gulf of Mexico (GOM) where they exert harmful effects on aquatic biota and humans. Because productivity on the WFS is N limited, new N inputs into the region are thought to trigger blooms of K. brevis. Here we examine the potential for new N inputs via N2 fixation by Trichodesmium and other diazotrophic plankton to contribute to the N demand of K. brevis. Because of possible methodological biases, we also compared N2 fixation rates by cultured Trichodesmium using the 15N2 bubble addition method and the 15N2 saturated seawater. Both methods yielded identical results in 12 and 24 h incubations; however, there was more variability in rate estimates made using the bubble addition method. Pelagic N2 fixation rates by other planktonic diazotrophs ranged from 0 to 13.6 nmol N L−1 d−1, comparable to or higher than rates observed in oligotrophic gyres. These rates should be considered conservative estimates because they were made using the bubble addition method. Integrating over our study area, we estimate that new inputs of N to the WFS via N2 fixation are on the order of 0.011 Tmol N annually. Further, we measured directly the trophic transfer of recently fixed N2 to co-occurring plankton that included K. brevis and found that up to 47% of N2 fixed was transferred to non-diazotrophic plankton even in short (
... Large numbers of juvenile Macrosetella have also been found associated with Trichodesmium in ... more ... Large numbers of juvenile Macrosetella have also been found associated with Trichodesmium in waters off Japan (Tokioka & Bieri, 1966 ; Ohki ... the two dominant species of Trichodesmium, T thiebautii and T ery-thraeum by Macrosetella gracilis and Miracia effer-ata were also ...
O'Neil, JM, Albert, S., Osborne, N., Shaw, GR, Heil, CA, Mulholland, M. and Bronk, DA (2004)... more O'Neil, JM, Albert, S., Osborne, N., Shaw, GR, Heil, CA, Mulholland, M. and Bronk, DA (2004). Nitrogen acquisition by the toxic marine cyanobacterium Lyngbya majuscula from Moreton Bay Australia and Tampa Bay Florida. In: , Harmful Algae. XIth International Conference ...
... Brown and Boyd, 1982) and intoxication due to ingestion of sea-turtle meat and macroalgae epi... more ... Brown and Boyd, 1982) and intoxication due to ingestion of sea-turtle meat and macroalgae epiphytised by L. majuscula (Osborne et al ... wracks of decaying L. majuscula by local government for health and aesthetic reasons (Dennison and Abal, 1999 and O'Neil and Dennison ...
Limnol. Oceanogr., 51(5), 2006, 2484 E 2006, by the American Society of Limnology and Oceanograph... more Limnol. Oceanogr., 51(5), 2006, 2484 E 2006, by the American Society of Limnology and Oceanography, Inc. ... Erratum: Nitrogen fixation and release of fixed nitrogen by Trichodesmium spp. in the Gulf of Mexico ... There is an error in our paper published in L&O 51: ...
Summary Intensive sampling of the Maryland Coastal Bays in May and July of 2007 served to further... more Summary Intensive sampling of the Maryland Coastal Bays in May and July of 2007 served to further assess spatial patterns in nutrients, responses of biological indicators, seasons, land use, and nutrient cycling. Studies conducted in 2004 and 2006 had pinpointed the regions of St. Martin River and Johnsons Bay as areas of degraded water quality, high turbidity, increasing total nitrogen and phosphorus concentrations, high natural isotope abundance (δ15N), and low dissolved oxygen. Therefore the current study sought to ...
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