Induced turbulence in rotating bottles affects phytoplankton productivity measurements in turbid waters

Enclosing phytoplankton in bottles to measure photosynthesisimposes an artificial environment on the sample that can influencerate processes. The absence of turbulence inside incubationbottles can affect productivity measurements by altering boththe irradiance level and sedimentation rates of confined cellsand particles. In Fourleague Bay, LA, a turbid lagoon-estuary,we compared productivity measurements in motionless bottlesto those in bottles that were continuously rotated at 15 r.p.m.to prevent the sedimentation of bottle contents. Productivitydiffered significantly in rotating and non-rotating treatments.At low light levels, rotation often enhanced production, probablydue to increased average irradiance. At high light levels, rotationreduced productivity by 10–83%, probably due to increasedphotoinhibition because the average position of the planktonwas closer to the light source than those in non-rotated bottles.Furthermore, in non-rotated bottles a greater proportion ofsediment particles and cells settled to the bottom, potentiallyshielding cells from photoinhibition. Cell density of the 8µm fraction was nearly 100% higher at the bottom of non-rotatedbottles (2.5+10⁸ cells l^–1) than at the surface aftera 3.5 h incubation. In quiescent water samples, light increasedby >35% in 20 min as a result of rapid particle settlingwhen stirring ceased. Integrated production rates were overestimatedin non-rotated samples by up to 95%, demonstrating the importanceof maintaining a cell-particle suspension which approximatesthat in situ when measuring productivity in turbid systems.     

Modelling phytoplankton productivity in turbid waters with small euphotic to mixing depth ratios

A model which was developed and calibrated for predicting algalgrowth in mass cultures, was modified for natural systems. Inturbid systems the ratio of euphotic to aphotic depth is usuallysmall and mixing may exceed the compensation depth. In orderto compensate for the various light regimes to which the phytoplanktonwould be subjected, the losses due to dark respiration weremodified so that the effective light history would determinethe actual rate. The efficiency of light utilization also changesunder different light regimes and the model was modified totake these variations into account. Both these modificationsresulted in different production profiles being generated forthe same surface conditions, but with different mixing depths,where the phytoplankton become more efficient as the light regimedeteriorates (i.e. less respiration and greater light utilizationefficiency). A further consequence is that the ‘criticalmixing depth’ is {small tilde}2.5 times greater than thatwhich was previously accepted, being {small tilde}20 times theeuphotic depth. The model predicted productivities to within90% of observed rates. It was also suggested how the predictionscould be used to determine the extent of nutrient limitation.The predictions also have biomanipulatory consequences, as alterationsof the light regime through the addition of non-photosynthesizingmaterials, under certain conditions, may even result in a stimulationof phytoplankton productivity.     

Phytoplankton productivity in findley lake

Findley Lake is a dimictic, oligotrophic, subalpine lake located in the western Cascade Mountains, Washington. The lake is snow covered for most of the year so that the growing season was 3.5 months in 1971 and 4.5 months in 1972. Rapid melt of the lake's snow cover in summer allowed the sudden development of a phytoplankton productivity maximum (as measured by the ¹⁴C tracer method) of 86 mg m⁻² hr⁻¹ and a peak of 48 mg chlorophyll a per m¹ within two weeks of surface clearing in 1972, followed by a rapid decline of productivity and biomass. Annual production (between 10 October, 1971 and 21 October, 1972) was 36 g/m² in the 27.5 m water column. Autotrophic carbon assimilation during the snow-covered period was insignificant. The total production for the lake in 1972 was 530 kg carbon. The concentration of available nitrogen (NO₂ + NO₃ + NH₃ as N) at 15 m ranged from 12 to 76 mg/m³ while PO₄-P ranged from 0.5 to 8.3 mg/m³. In vitro nutrient enrichment experiments with natural phytoplankton communities from the lake indicated that while N and P together were growth limiting, P alone produced a growth response while N alone did not. Contributions to production from net-, nanno-, and ultraplankton were determined by fractional filtration of ¹⁴C-labeled phytoplankton samples. The nannoplankton, dominated by diatoms, accounted for 58% to 94% of productivity.     

Environmental control of phytoplankton productivity in turbulent turbid systems

Factors affecting phytoplankton productivity are analysed in turbid systems, such as shallow lakes and rivers. When resuspension from the sediment or loading from the catchment significantly increases inorganic (non-algal) turbidity and hence light attenuation potentials for high production are not realised. Energy available for phytoplankton growth is strongly regulated by underwater light availability which depends on the critical mixing depth, fluctuating light intensities and algal circulation patterns. Higher production rates in shallow waters are often compensated by greater algal respiration due to higher water temperatures when compared to deeper lakes.Total daily integral production of turbulent, turbid environments can be predicted from a combination of easily measured variables such as maximum photosynthetic rates, algal biomass, surface irradiance and some measure of underwater light attenuation.     

Navigation by light polarization in clear and turbid waters

Certain terrestrial animals use sky polarization for navigation. Certain aquatic species have also been shown to orient according to a polarization stimulus, but the correlation between underwater polarization and Sun position and hence the ability to use underwater polarization as a compass for navigation is still under debate. To examine this issue, we use theoretical equations for per cent polarization and electric vector (e-vector) orientation that account for the position of the Sun, refraction at the air-water interface and Rayleigh single scattering. The polarization patterns predicted by these theoretical equations are compared with measurements conducted in clear and semi-turbid coastal sea waters at 2 m and 5 m depth over sea floors of 6 m and 28 m depth. We find that the per cent polarization is correlated with the Sun's elevation only in clear waters. We furthermore find that the maximum value of the e-vector orientation angle equals the angle of refraction only in clear waters, in the horizontal viewing direction, over the deeper sea floor. We conclude that navigation by use of underwater polarization is possible under restricted conditions, i.e. in clear waters, primarily near the horizontal viewing direction, and in locations where the sea floor has limited effects on the light's polarization.     

Phytoplankton and pelagic primary productivity in Øvre Heimdalsvatn

A phytoplankton investigation was carried out in the subalpine, low-productive Norwegian lake Øvre Heimdalsvatn in 1969–70 and 1972. This paper describes the temporal and spatial distribution of the standing stock of phytoplankton, and phytoplankton primary productivity. The annual average primary productivity in 1972 was 4.0–4.9 mg C m⁻³ d⁻¹; the annual average standing stock varied from 120 mg m⁻³ (freshweight) in 1969–70, to 250 mg m⁻³ in 1972. Phytoplankton species composition and size distribution is discussed. Throughout the year the phytoplankton is dominated by small (ultraplankton) species; μ-algae (< 5 μm) showed cell concentrations up to 15 mill. cells 1⁻¹. The dominating group was chrysophytes; cryptophytes, dinoflagellates or green algae were at times abundant. A phytoplankton monthly budget and a diagram showing annual average carbon flow through the standing stock of phytoplankton are presented; the phytoplankton dynamics in Øvre Heimdalsvatn is compared to that of other low-productive lakes.     

The contribution of phytoplankton productivity in turbid freshwaters to their trophic status

Certain factors influencing phytoplankton productivity are accentuated in turbid waters. They include mixing, spectral quality shifts, scattering, light fluctuations, and overall light attenuation. Measurements of productivity is influenced by the presence of inorganic turbidity. Together with the above factors high turbidity causes difficulties to assess and model phytoplankton productivity. Estimations of ^B, P_m ^B, I_k and _m only reflect on the physiological condition of the phytoplankton, which differs little between water types of temperate regions. Measurement of integral vertical productivity, efficiency and fractional absorption by the phytoplankton of light energy conversion, however, are greatly influenced by inorganic turbidity. Because of high ratios of mixing to euphotic depth, the critical mixing depth is one of the most important factors influencing overall productivity in turbid waters.     

厦门近岸海域大型底栖动物次级生产力

于2013年5月和11月在厦门近岸海域设置67个站位进行大型底栖动物定量调查,运用Brey(1990)经验公式对该海域的次级生产力进行估算。结果表明:该海域大型底栖动物年均总次级生产力P和P/B值分别为4.6±10.1 g AFDW·m-2·a-1和1.0±0.4a-1,软体动物和多毛类为该海域P值的主要贡献类群,秋季的P值略高于春季,同安湾的P值明显高于大嶝海域、九龙江口、厦门外海域和围头湾。相关性分析显示,该海域次级生产力与沉积物有机质含量以及水体底温呈显著相关,底质类型以及采砂、航道清淤、环境污染等人类活动干扰也是影响次级生产力分布的主要因素。     

南沙群岛邻近海区春夏季浮游植物多样性研究

1999年春季和夏季对南沙海区网采浮游植物分布与多样性进行了调查。 1999年春季渚碧礁湖观测站及春、夏季大面站的浮游植物细胞数量平均值分别为 2 .4 9× 10 4cells/m3 、0 .73× 10 4cells/m3 和 1.0 3× 10 4cells/m3 。1999年春季在渚碧礁湖共采到浮游植物 2 6属 5 1种 ,大面站 31属 10 9种 ;夏季大面站共检出 38属 172种。海区大面站春季、夏季浮游植物Shannon Wiener多样性指数平均值分别为 4 .35和 4 .0 1;春季渚碧礁浮游植物多样性指数为 2 .92 ,低于外部开阔海域。南沙海区浮游植物的分布与水文、营养盐、浮游动物的摄食等均有一定的关系     

Fish-mediated zooplankton community structure in shallow turbid waters: a mesocosm study

Wetlands Ecology and Management - Turbidity influences the success of fish feeding, but little is known about the difference in the effects of turbidity as a result of organic and inorganic matter....     

Selection of a suitable cladoceran species for toxicity testing in turbid waters

Abstract Two Australian cladocerans, Moina australiensis Sars and a species of Ceriodaphnia, were evaluated as possible biological indicator organisms to assess the toxicity of irrigation supply and drainage water of the Murrumbidgee and Coleambally Irrigation Areas. M. australiensis, being large (～2000 μm) and orange, was initially chosen to overcome visibility problems in highly turbid Australian inland waters. However, the organism responded erratically in culture. Mortality was high and neonate production was unpredictable when cultured under recommended United States Environmental Protection Agency protocols. Attempts to improve culture performance by optimizing food (quality and quantity), water (control source, hardness, volume) and temperature were only marginally successful. Similar difficulties were not evident when Ceriodaphnia sp. was used as the test organism. Although Ceriodaphnia sp. is small (～1000 μm), grey and more difficult to see in turbid water its responses were more predictable and reliable than those of M. australiensis. Results of initial trials comparing the two organisms suggest that Ceriodaphnia sp. was a better test organism and more suited to local requirements.     

Phytoplankton productivity and chlorophyll-A concentration of Oguta Lake in Southeastern Nigeria

The phytoplankton productivity and chlorphyll-a concentration of Oguta Lake, the largest natural lake in south-eastern Nigeria, are presented (Dec. 1983. Nov. 1984). The gross productivity ranged from 1.3 to 3.77 g C.m^–2.day^–1 for the water column, dropped during the period of heavy rainfall and varied with depth. The chlorophyll-a concentration had monthly means ranging from 2.31 to 4.00 mg.m^–3, with a drop during the rains, but little depth variation. Both productivity and chlorophyll-a showed non-significant correlation with the physico-chemical features of the water. The values of the biological parameters showed the lake as mesotrophic. The values are compared with those of other African lakes.     

The photosensitive retinal pigments of fishes from relatively turbid coastal waters

Digitonin extracts have been prepared from the retinae of a dozen species of marine and euryhaline teleost fishes from turbid water habitats. Spectrophotometric analysis of the extracts shows that the photosensitive retinal pigments of these species have maximum absorption above 500 mµ. In nine species there are retinene₁ pigments with λ_max between 504 and 512 mµ. In the marine but euryhaline mullet, Mugil cephalus, there is a porphyropsin with λ_max 520 mµ. A mixture of rhodopsin and porphyropsin in an extract of a marine puffer, Sphoeroides annulatus, was disclosed by partial bleaching with colored light. In addition, one other species has a 508 mµ pigment, of which the nature of the chromophore was not determined. The habitats in which these fishes live are relatively turbid, with the water greenish or yellowish in color. The spectral transmission of such waters is probably maximal between 520 and 570 mµ. It is suggested that the fishes have become adapted to these conditions by small but significant shifts in spectral absorption of their retinal pigments. These pigments are decidedly more effective than rhodopsin in absorption of wavelengths above 500 mµ. This offers a possible interpretation of the confusing array of retinal pigments described from marine and euryhaline fishes.     

Phytoplankton composition of the New York Bight and adjacent waters

The New York Bight possesses a diverse assemblage of phytoplanktonwhere seasonal periods of high growth are dominated by several,chain-forming diatoms and a pico-nanoplankton component Thecomposition is similar to other regions of the northeasternshelf, producing late winter-early spring and fall maxima.     

Phytoplankton community structure and environment in the Kenyan waters of Lake Victoria

• 1 Phytoplankton species composition, numerical abundance, spatial distribution and total biomass measured as chlorophyll a concentration were studied in relation to environmental factors in September 1994 (dry season) and March 1995 (rainy season), respectively, in the Kenyan waters of Lake Victoria; 103 species were recorded.
• 2 Blue‐green algae (Cyanophyceae) were most diverse, followed by diatoms (Bacillariophyceae), green algae (Chlorophyceae) and dinoflagellates (Dinophyceae).
• 3 Twinspan separated the phytoplankton communities in the Nyanza Gulf and those in the open lake during both seasons. During the dry season, the Nyanza Gulf was strongly dominated by blue‐greens, while diatoms dominated in the open lake. During the rainy season, blue‐greens remained dominant in the Nyanza Gulf although the number of species found was lower than during the dry season; in the open lake, blue‐greens replaced diatoms as the dominant group and there were more species than in the dry season.
• 4 Canonical correspondence analysis indicated that the phytoplankton species distribution was significantly correlated with turbidity during the dry season and with SiO₂ during the rainy season. Chlorophyll a concentrations ranging from 2.0 to 71.5 mg m^‐3 in the dry season and 2.0–17.2 mg m^‐3 in the rainy season confirm earlier reports of increasing phytoplankton biomass in Lake Victoria since the 1960s.

     

Phytoplankton structure and dynamics in a turbid Antarctic lake (Potter Peninsula, King George Island)

Qualitative and quantitative changes in the freshwater phytoplankton from one of the largest lakes in Potter Peninsula were studied during the summer period of 1995/1996. The main limnological features were analysed. This research constitutes the first study dealing with the phytoplankton structure and dynamics from lakes in Potter Peninsula. Due to the mixing of the water column by the constant wind action during the ice-free period, neither physical, chemical nor biological parameters showed differences between depths. Soluble reactive phosphorus remained low (26 μg l⁻¹) while total phosphorus concentrations were up to 232 μg l⁻¹. Suspended solids and total phosphorus differed significantly between the two basins in which the lake is divided. Sixty-five taxa were identified. The Bacillariophyceae was the dominant class followed by Chrysophyceae. Achnanthes lanceolata var. haynaldii and Hydrurus foetidus (cysts) were the dominant species. Tychoplanktonic species were the best represented in terms of abundance and species richness. The principal component analysis carried out with abiotic variables showed a temporal gradient characterised by the augmentation of suspended solids, total phosphorus, conductivity, pH and NH₄-N to the end of the summer period. The Principal Component Analysis performed with biotic variables also showed a temporal trend related to a decline in phytoplankton density and an enhancement of chlorophyll-a despite a slight increase of light limitation during the study period. This inverse relation may be due to the presence of picoplankton in chlorophyll-a samples. The potential effect of grazing on the phytoplankton structure is a subject to be tested in future studies. Accepted: 7 February 1999     

Phytoplankton community growth-rate response to nutrient pulses in a shallow turbid estuary, Galveston Bay, Texas

Phytoplankton growth is a physiological process often limitedby temperature, nutrients or light, while biomass accumulationis a function of growth rates, grazing and deposition. Althoughprimary productivity measurements are usually used to assessresponses to limiting factors, the rates are proportional tobiomass and inversely related to grazing pressure during experimentalincubations. Alternatively, carbon-specific growth-rate determinationsprovide insights into physiological responses without the confoundingeffects of biomass and grazing. The objective of this studywas to quantify the growth-rate responses of phytoplankton toenhanced nutrient availability (nitrate and phosphate) overa range of in situ irradiances. Growth rates were determinedbased on chlorophyll a-specific ¹⁴C-uptake rates by phytoplankton.Phytoplankton demonstrated high (24 h) growth rates when exposedto increased concentrations of limiting nutrients, independentof the surface irradiances (12–41%). Growth-rate responseswere also compared with the biomass (chlorophyll a) responsesand community composition. Observed and estimated phytoplanktonbiomass changes during the incubations differed, emphasizingthe structural role of grazers on the phytoplankton community.The phytoplankton community in Galveston Bay has the potentialto instantaneously respond to nutrient pulses, facilitatingdiatom biomass accumulations in spring and summer and small,flagellated species and cyanobacteria during periods of lownutrient inputs. Thus, Galveston Bay phytoplankton biomass andcommunity composition reflect a dynamic balance between thefrequency of nutrient pulsing and grazing intensity.     

Abundance and productivity of heterotrophic nanoplankton in Georgia coastal waters

The population abundances and rates of biomass production ofheterotrophic nanoplankton (HNAN) in Georgia coastal waterswere evaluated by epifluorescence microscopy. HNAN populations(mostly non-pigmented microflagellates <10 µm in diameter)ranged from 0.3 x 10³ cells ml^–1 in shelf waters 15 kmoffshore to 6.3 x 10³ cells ml^–1 in waters 0.25 km fromthe coast. There was a strong correlation (r = 0.83) betweenHNAN and free bacterioplankton population abundances, but noapparent relation (r = 0.38) between HNAN and phototrophic nanopLankton(PNAN) abundances. HNAN biomass production in estuarine andnearshore shelf waters, as estimated from increases in HNANpopulations during laboratory incubations of natural water samples,ranged from 0.10 to 0.79 mg C m^–3 h^–3, with populationgeneration times of 9.7 to 26.5 h. There was a significant linearrelation (r = 0.95) between HNAN biomass and HNAN productivity.We calculated that HNAN may graze at least 30% to 50% of dailybacterioplankton production in Georgia coastal waters.     

长江口及其邻近水域冬季浮游植物群集

应用Uterm hl方法分析了2005年2月28日至3月10日在长江口及其邻近水域进行的大面调查所获浮游植物采水样品,报道了该水域浮游植物的群落特征.初步鉴定浮游植物5门67属130种(含未定名25种).调查水域浮游植物群落主要由硅藻组成,其次为甲藻,此外还有少量的金藻、蓝藻和绿藻.主要优势种为具槽帕拉藻(Paralia sulcata)、中肋骨条藻(Skeletonema costatum)、圆海链藻(Thalassiosira rotula)、标志布莱克里亚藻(Bleakeleya nota-ta)、辐射圆筛藻(Coscinodiscus radiatus)和离心列海链藻(Thalassiosira excentrica).调查区浮游植物的细胞丰度介于0.1~90.0cells.ml-1,平均值为10.1cells.ml-1.浮游植物的水平分布特征是近岸处浮游植物丰度高,远岸处丰度低.水体表层的浮游植物细胞丰度最高,表层之下细胞丰度略有降低,但变化不大.浮游植物的细胞丰度和叶绿素a与硝酸盐、亚硝酸盐、铵盐、磷酸盐和硅酸盐浓度呈显著正相关,而与盐度呈负相关.调查区中部香农-威纳多样性指数和Pielou均匀度指数较高,而东北部和近岸水域较低.     

Phytoplankton dynamics,primary productivity and community metabolism in a north-central Texas pond

Phytoplankton diversity, primary productivity and community metabolism were measured for 1 year in a 0.94 ha pond located in north-central Texas. Gross primary production ranged from 4.5 to 46.8 kcal m⁻² day⁻¹ ( =22.0 kcal m⁻² day⁻¹) and community metabolism ranged from 7.3 to 32.4 kcal m⁻² day⁻¹ ( =14.8 kcal m⁻² day⁻¹). Average production/respiration ratio (1.5) showed that the pond was principally autotrophic. Photosynthetic efficiency (gross primary production/0.5 total solar radiation) ranged from 0.32 to 2.8 with a mean of 1.2. Phytoplankton diversity based on numbers and biomass fluctuated greatly. Highest gross primary productivity occurred during Cyanophyta blooms in late summer-early fall when species diversity was minimal. Water temperature and turbidity, which governed light penetration, were the principal determinants of primary production.