Aphanizomenon Flos-aquae Blooms Research Articles

Relation between the relative abundance and collapse of Aphanizomenon flos-aquae and microbial antagonism in Upper Klamath Lake, Oregon.

Aphanizomenon flos-aquae (AFA) is the dominant filamentous cyanobacterium that develops into blooms in Upper Klamath Lake, Oregon, each year. During AFA bloom and collapse, ecosystem conditions for endangered Lost River and shortnose suckers deteriorate, thus motivating the need to identify processes that limit AFA abundance and decline. Here, we investigate the relations between AFA and other members of the microbial community (photosynthetic and nonphotosynthetic bacteria and archaea), how those relations impact abundance and collapse of AFA, and the types of microbial conditions that suppress AFA. We found significant spatial variation in AFA relative abundance during the 2016 bloom period using 16S rRNA sequencing. The Pelican Marina site had the lowest AFA relative abundance, and this was coincident with increased relative abundance of Candidatus Sericytochromatia, Flavobacterium, and Rheinheimera, some of which are known AFA antagonists. The AFA collapse coincided with phosphorus limitation relative to nitrogen and the increased relative abundance of Cyanobium and Candidatus Sericytochromatia, which outcompete AFA when dissolved inorganic nitrogen is available. The data collected in this study indicate the importance of dissolved inorganic nitrogen combined with microbial community structure in suppressing AFA abundance.

Evaluating the dynamics of groundwater, lakebed transport, nutrient inflow and algal blooms in Upper Klamath Lake, Oregon, USA

Transport of nutrients to lakes can occur via surface-water inflow, atmospheric deposition, groundwater (GW) inflow and benthic processes. Identifying and quantifying within-lake nutrient sources and recycling processes is challenging. Prior studies in hypereutrophic Upper Klamath Lake, Oregon, USA, indicated that ~60% of the early summer phosphorus (P) load to the lake was internal and hypothesized to be lakebed sediment release. Dynamic nutrient transport processes were examined to better characterize the nutrient sources. One-dimensional heat transport models calibrated to observed lakebed temperatures and a cross-sectional GW flow model provided estimates of GW-inflow rates that were greatest in spring and decreased through summer. One-dimensional solute transport models calibrated to observed lakebed pore-water dissolved silica (Si) and dissolved phosphate-phosphorus (DP) concentrations indicated that nutrients were transported from the lakebed by advection, diffusion, and enhanced mixing by benthic organisms and waves, and that DP removal occurred near the lakebed interface. Estimated water, Si, DP and total-phosphorus (TP) budgets indicated that GW contributed 21% of lake water inflow and at least 26, 20 and 16% of total Si, DP and TP inflow, respectively, when conservatively assuming background GW nutrient concentrations. However, lakebed GW (LGW) is enriched in nutrients during flow through lakebed sediment and the estimated GW contribution increased to 29 (33), 49 (67) and 43% (61%) of total Si, DP and TP inflow, respectively, if 20% (50%) of GW inflow to the lake was assumed to have LGW concentrations. Net nutrient inflow to the lake was greatest in spring and coincident with the annual diatom bloom. Inflowing dissolved nutrients appear to be assimilated by diatoms during the spring and become available for the summer Aphanizomenon flos-aquae bloom when the diatoms senesce. Thus, nutrient-enriched GW inflow and nutrient recycling by successive algal blooms must be considered when evaluating internal nutrient loading to lakes.

A large-scale sustained fish kill in the St. Johns River, Florida: A complex consequence of cyanobacteria blooms

In the summer of 2010, a sustained multispecies fish kill, affecting primarily adult red drum (Sciaenops ocellatus) and Atlantic stingray (Dasyatis sabina), along with various baitfish such as menhaden (Brevoortia spp.) and shad (Dorosoma spp.), was documented for six weeks along 50 km of the Lower St. Johns River (LSJR), Florida. An Aphanizomenon flos-aquae bloom was present in the freshwater reaches before the fish kill. The kill was triggered by a significant reverse-flow event and sudden influx of high-salinity water in late May that contributed to the collapse of the bloom upstream and brought euryhaline fish downstream into the vicinity of the senescing bloom or its by-products. The decomposing bloom led to a sequence of events, including the release of small amounts of cyanotoxins, bacterial lysis of cyanobacterial cells, high organic loading, and changes in the diversity and dominance of the plankton community to include Microcystis spp., Leptolyngbya sp., Pseudanabaena spp., Planktolyngbya spp., and low concentrations of Heterosigma akashiwo. Dissolved oxygen levels were within normal ranges in the reach of the fish kill, although elevated ammonia concentrations and high pH were detected farther upstream. These conditions resulted in complex pathological changes in fish that were not consistent with acute cyanotoxin exposure or with poor water quality but were attributable to chronic lethal hemolysis. Potential sources of hemolytic activity included H. akashiwo, Microcystis spp., and Bacillus cereus, a hemolytic bacterium. The continued presence of A. flos-aquae in the LSJR could have significant environmental repercussions and ideally the causal factors contributing to bloom growth and maintenance should be fully understood and managed.

Changes in antioxidant enzyme activities in the livers and gills of three cyprinids after exposure to a cyanobacterial bloom in the Gruža Reservoir, Serbia

We examined the influence of an Aphanizomenon flos-aquae bloom on the activities of antioxidant enzymes in the livers and gills of three cyprinids, Rutilus rutilus (roach), Blicca bjoerkna (white bream) and Carassius gibelio (Prussian carp) from the Gruža Reservoir (Serbia). We also studied tissue- and species-specific differences in the antioxidant response to the cyanobacterial bloom. The activities of total, copper zinc and manganese containing superoxide dismutases (Tot SOD, CuZn SOD, Mn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and the biotransformation phase II enzyme glutathione-S-transferase (GST) were determined before and during the cyanobacterial bloom. B. bjoerkna exhibited higher antioxidant response to the cyanobacterial bloom than R. rutilus and C. gibelio; liver Tot SOD, CuZn SOD and GST activities increased during the bloom only in this species. Liver Mn SOD activity in all three cyprinids increased during the bloom. A decrease in liver CAT and GSH-Px activities that was detected in all three species may be directly responsible for an enhanced susceptibility of fish to potential oxidative stress caused by the bloom. Tot SOD, CuZn SOD, Mn SOD, GSH-Px, GR and GST activities in gills were also inhibited during the bloom showing that the gills were affected more than the liver. The observed changes in the activities of aforementioned antioxidant enzymes during the cyanobacterial bloom suggest that these parameters could be important biomarkers for ecotoxicological risk in fish that inhabit ecosystems where A. flos-aquae blooms occur.

Biochemical and ultrastructural changes in the liver of European perch (Perca fluviatilis L.) in response to cyanobacterial bloom in the Gruza reservoir

We investigated the biochemical and ultrastructural changes in the liver of the freshwater fish, European perch (Perca fluviatilis), in response to Aphanizomenon flos-aquae bloom in the Gruza Reservoir, Serbia. The activities of total manganese- and copper zinc-containing superoxide dismutase (Tot SOD, Mn-SOD, Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and biotransformation phase II enzyme glutathione-S-transferase (GST), as well as concentrations of total glutathione (GSH) and sulfhydryl (-SH) groups were examined before and during the bloom period. Mn-SOD activity was significantly higher, while the activities of Cu/Zn-SOD, CAT and GSH-Px and the concentration of the -SH groups were significantly lower during the bloom. The ultrastructure of the liver revealed necrotic and apoptotic damage to the hepatocytes during the bloom period. Our work represents the first study to report the influences of an Aphanizomenon flos-aquae bloom in the Gruza Reservoir on antioxidant biomarkers and on histopathological alterations in the liver of the freshwater fish European perch (Perca fluviatilis).

Phosphorus Fractionation in Sediment Cores Collected In 2005 Before and After Onset of an Aphanizomenon flos-aquae Bloom in Upper Klamath Lake, OR, USA

We tested the hypothesis that there would be measurable losses of phosphorus (P) from surficial sediments of Upper Klamath Lake (UKL), Oregon, if sediments were a source of P during an algal bloom. We compared concentrations of total and forms of P at various depths in cores collected before and after the onset of a large Aphanizomenon flos-aquae bloom. Concentrations of inorganic P were determined in extraction solutions of MgCl2 (1 M, pH 8), citrate-dithionite-bicarbonate, and 1 M HCl. Sediments below 2 cm were dominated by residual P which is defined as total P minus inorganic P. During the study period, data from the top 2-cm of sediment indicated (a) significant decrease in total P concentration, primarily associated with iron oxyhydroxides at one site, and (b) significant increase in total P concentration associated with residual P at a second site. Data from two other sites indicated no net changes in concentrations of total P.

The formation and degradation of cyanobacterium Aphanizomenon flos-aquae blooms: the importance of pH, water temperature, and day length

Investigation of annual changes in phytoplankton community structure in a small artificial eutrophic pond was carried out from May 2002 to April 2003. A heavy bloom of Aphanizomenon flos-aquae var. klebahnii Elenk. (Cyanobacteria) persisted in most of the water column from June to the end of October. In November, the A. flos-aquae bloom suddenly crashed and green algae were predominant until the end of spring. Weekly monitoring suggested strong involvement of the changes in abiotic factors in the cyanobacterial bloom degradation. To clarify the effects of pH, water temperature, and day length on the growth of A. flos-aquae, laboratory batch experiments were conducted. The results showed that A. flos-aquae could not grow below pH 7.1 and 11°C, and the growth tended to be suppressed under a 10L:14D photoperiod. pH, water temperature, and day length are vital factors in the growth of A. flos-aquae and, additionally, grazing by cyclopoid copepods also seemed important in bloom collapse.

Effects of Copper on Nitrogen Fixation and Growth of Blue-Green Algae in Natural Plankton Associations

Copper toxicity bioassays were conducted on six stages of the spring Aphanizomenon flos-aquae bloom in eutrophic Clear Lake, California. Major variables tested were nitrogen fixation, carbon fixation, pigments, and cell numbers. Inhibition of nitrogen fixation, carbon fixation, and pigment accumulation increased linearly between 10 and 30 μg Cu/L. Higher concentrations produced little additional toxicity. In contrast, there was a stimulatory effect of copper, especially on nitrogen fixation, at the very low level of 2 μg/L. There was no inhibitory effect of copper on nitrogen fixation without a comparable or greater effect on carbon fixation or chlorophyll a. Other algae growing with the Aphanizomenon bloom were not affected by additions of copper up to 20–30 μg Cu/L, but were affected at the 50–100 μg/L level.Key words: algae, algicide, blue-green algae, copper, cyanobacteria, metal, limiting nutrient, nitrogen fixation, photosynthesis, phytoplankton, toxicity

Experimental Manipulation of Algal Bloom Composition by Nitrogen Addition

Nitrogen (as ammonium, nitrate, or both) was added over an 8- to 12-wk period to enclosures in a small prairie lake and to a whole pond. In previous years, both had experienced seasonal anoxia as a result of collapses of Aphanizomenon flos-aquae blooms followed by a massive fish kill. Additions altered the bloom magnitude and the species composition if N was added prior to the appearance of A. flos-aquae. Low additions (~ 0.75–1.5 g m−8∙wk−1) initiated after the appearance of the cyanophyte bloom resulted in a significant reduction of the A. flos-aquae biomass, while the same addition at the time of a chlorophyte bloom (Scenedesmus and Oocystis sp.) caused a substantial shift to Microcystis aeruginosa. High additions (~ 7–14 g m−3∙wk−1) resulted in a total absence of cyanophytes and were followed by a complete shift to small chlorophytes and cryptomonads, with a total absence of A. flos-aquae and the fish kill. Low additions of N did not show any accumulation over 3–5 mo after discontinuation of the fertilization; high additions showed a significant accumulation of nitrate in the water. Both lake and pond returned to heavy A. flos-aquae blooms and fish kills the following summer when not fertilized.Key words: nutrient enrichment, nitrogen, algal blooms, fish kills, oxygen depletion, prairie lakes, biomanipulation, eutrophication

Collapses of Aphanizomenon flos-aquae blooms resulting in massive fish kills in eutrophic lakes: effect of weather

(1978). Collapses of Aphanizomenon flos-aquae blooms resulting in massive fish kills in eutrophic lakes: effect of weather. SIL Proceedings, 1922-2010: Vol. 20, No. 1, pp. 208-213.

Efficacy of copper sulphate in the suppression of Aphanizomenon flos-aquae blooms in prairie lakes

Five shallow eutrophic prairie lakes in the Erickson-Elphinstone area of Manitoba were treated with copper sulphate in order to control Aphanizomenon flos-aquae blooms and prevent summer fish kills. Copper sulphate was added at concentrations of 25 to 360 μg/l Cu to lakes and 100 to 3000 μg/l Cu to experimental tubes in early July when A. flos-aquae filaments were about 10 mm in length. Pretreatment chlorophyll a concentrations were 48 to 55 μg/litre and bloom species compositions were 90 to 98 % of A. flos-aquae. Excellent algal control was achieved at all treatment concentrations. Typically chlorophyll a declined to 2 to 4 μg/litre after 4 days and A. flos-aquae completely disappeared. Algal biomass remained low for 2 to 3 weeks and then gradually increased. Often Chlorophyta, diatoms and chrysophytes dominated the algal community for the rest of the ice-free season, although in two lakes other species of cyanophyta ( Microcystis sp.) were predominant. Low concentrations ranging between 25 and 40 μg/litre Cu proved to be effective enough in these lakes. Copper concentration in the water returned to background levels after 8 to 10 days.

General and applied hydro-biology, particularly as a vehicle of schistosoma. Hypereutrophy, modern deterioration of water

Observações hidrobiológicas do Lago de Brasília, em 1965, mostraram algas planctônicas Desmidiaceae predominantes, com espécies dos gêneros Staurastrum, Micrasterias, Euastrum, Cosmarium Xanthidium, Bambusina, Closterium, Spondilosium, Penium, principalmente, de águas puras e naturais; conforme o texto, são sêres comuns nas águas indígenas do Brasil Central. Mas a nova capital brasileira cresceu ràpidamente, alcançando oerto de meio milhão de habitantes: a influência do homem se apresentou e, em 1968, já causava outro regime hidrobiológico dentro das faixas de saprobidade, com planctos cosmopolitas indicadores de poluição. Encontramos águas já mesossapróbias com cianofíceas indesejáveis em quantidades maciças, como as Aphanizomenon flos-aquae, a Anacystis cyanea (= Microcystis aeruginosa), Anabaenopsis, Gomphosphaeria e outras. O lago que era "Lago de Desmidiáceas" passou a ser um "Lago de Cianofíceas". Os índices de eutrofização dependem de eutrofizantes no numerador, divididos por desmidiáceas no denominador. Quanto maior o número de algas eutrofizantes, tanto maior a eutrofização; exatamente o que acontece no lago de Brasília. os autores chamam a atenção para os estudos de saprobidade das águas do lago, baseado na teoria que os moluscos Planorbidae se instalem dependentes do regime de poluição mesossapróbio; supõe-se por isso a razão por que êsses moluscos acompanham o homem nas suas migrações. Poder-se-à determinar a faixa de saprobidade em que se instalam os moluscos, suspeitando-se entre os regimes A- e B- mesossapróbio. Propõem medidas preventivas de caráter hidrobiológico para evitar a instalação de planorbídeos. Embora os esgotos sejam todos muito bem tratados sanitàriamente e não há nenhum perigo ou queixa quanto a essa parte; mas é o resultado do tratamento de esgotos e restos de águas usadas pelo homem que fornecem nutritivos às àguas: N, P, Ca, Cl, K, etc. ... e que eutrofizam. A eutrofização normal é ótima; o lago fica produtivo de bom plancto e ótimos peixes. Para eutrofia em excesso, os autores criaram o nôvo têrmo HIPEREUTROFIA, descrevem êsses fenômenos, de ordem geral, com explosivo crescimento da população planctônica e fitoplanto mesossapróbio causador de calamitosos problemas. Pode a "hipereutrofia" ser considerada uma nova e grave "praga das águas" que surgiu depois da 2ª guerra mundial, devido á rápida industralização e explosão populacional do homem. Medidas preventivas contra a hipereutrofia poderão ser conseguidas com planejamentos integrados das bacias dos rios, lagos e baías evitando despejos de excessos de nutrientes, em zonas que fiquem como reservas, preservando a biota aquática natural e normal. É possível tal planejamento no Brasil, porque é um dos poucos países, com bacias de rios e lagos artificiais ainda não poluídos.