Autotrophic Picoplankton Biomass Research Articles

Comparative study of picoplankton biomass and community structure in different provinces from subarctic to subtropical oceans

Picoplankton biomass and community structure in the subtropical and subarctic Pacific Oceans were investigated during November 2003, April-August 2005 and July-August 2005. The sampling covered the subarctic K2 station, the Western North Pacific subtropical gyre (WNPG1 and 2 stations) and the Eastern North Pacific subtropical area (ENP1, 2, 3 and 4 stations). Distinct differences in community structure and autotrophic and heterotrophic picoplankton biomass were observed among the above provinces. In subtropical areas, the picoplankton community comprised Prochlorococcus, Synechococcus, picoeukaryotes and heterotrophic bacteria. While in the subarctic area (K2 station), Prochlorococcus were absent. Prochlorococcus were numerically dominant in the subtropical oceans, their abundance tended to decrease with increasing nutrient levels, which is the opposite of the other picoplankton populations. Although the aerobic anoxygenic phototrophic heterotrophic bacteria (AAPB), accounted for only a small proportion of total heterotrophic bacterial abundance, their potential contribution to carbon export may be important due to their larger cell size and higher cell turnover rates compared with other heterotrophic bacteria. Biomass contribution of the AAPB increased distinctly along the oligotrophic to relatively eutrophic gradient. Vertically, AAPB generally followed the phytoplankton except in the subtropical WNPG. Spatial variability of biomass in the autotrophic picoplankton was distinctly larger than that in the heterotrophic bacteria. Changes in the picoplankton community were more closely associated with latitude while nutrient availability was more important for differences in picoplankton biomass. The biomass of autotrophic picoplankton in the upper mixed layer, and also the depth attenuation, were higher in eutrophic relative to oligotrophic waters. Picoplankton seemed to be an important source of new organic carbon for higher trophic level organisms and for detritus production, especially in the oligotrophic subtropical gyre.

Biomass of autotrophic picoplankton in subtropical coastal lagoons: Is it relevant?

Biomass of autotrophic picoplankton in subtropical coastal lagoons: Is it relevant? The importance of the autotrophic picoplankton (APP, <2 μm) to the primary productivity of coastal lagoons has been recently recognized. However, the role of these organisms in highly dynamic systems such as coastal lagoons is not well understood. The Atlantic coast of Uruguay (34 ◦ 20 � -34 ◦ 54 � S; 53 ◦ 55 � -55 ◦ 00 � W) is characterized by the presence of a series of subtropical coastal lagoons (depth: 0.2-2.0 m) that differ in the dynamics of the interaction with the ocean, their salinity, morphometry, and anthropogenic impact. The relative contribution of eukaryotic and prokaryotic APP to the total phytoplankton biomass in five coastal lagoons was determined and its relation to the abiotic factors was analyzed. Phytoplankton was identified and quantified using flow cytometry and optical microscopy. Chlorophyll a (Chl-a) concentration was determined through seasonal samplings. The conductivity varied from limnic (< 0.3 mS/cm) to brackish conditions (36.6 mS/cm). The concentration of dissolved inorganic nitrogen and the DIN/SRP atomic ratio were generally low (ranging from undetectable to 107.2 μg/l, and from < 1 to 52.3 μg/l, respectively). The total Chl-a ranged from 0.7 to 18.3 μg/l from which the picoplanktonic fraction represented from 4.2 to 96.6 %. In general, the Chl-a picoplanktonic fraction was negatively correlated with the total concentration of Chl-a. The cytometric analysis of the picoplankton allowed the identification of six ataxonomic groups, indicating that picoeukaryote groups were dominant throughout the study, although picocyanobacteria were occasionally important. It was found that suspended solids and dissolved inorganic nitrogen were the most important factors related to the APP Chl-a contribution.

The significance of autotrophic and heterotrophic picoplankton in hypertrophic ecosystems

Hypertrophic aquatic ecosystems are biologically important because they represent an environment where homeostatic mechanisms are strongly reduced and extreme oscillations occur in physical and chemical parameters as well as in the growth of many planktonic organisms. Hypertrophic lakes may represent not only the ultimate state of eutrophication, but also systems where abundance and production of picoplanktonic organisms (0.2–2 μm in diameter) may theoretically be greatest. In this review we examined the microbial ecology literature for studies on hypertrophic lakes and assessed the significance of heterotrophic bacteria (BACT) and autotrophic picoplankton (APP). Our main conclusions are as follows: (a) The relative contribution of APP to total phytoplankton biomass is strongly reduced in hypertrophic systems. (b) The absolute abundance and biomass of APP are highly variable among these systems; depending mainly on differences in light quality and quantity, the existence of nitrogen limitation and presence of pollutants. (c) The abundance of BACT does not increase as rapidly as algal biomass with increasing trophy. (d) A clear dichotomy exists between lakes dominated by Microcystis where bacterial biomass and production are relatively low, and Planktothrix-dominated lakes where bacterial biomass and production are high. (e) Bacterial production per unit biomass tends to increase from oligotrophic to hypertrophic systems supporting the previous hypothesis that bacteria do not play a lesser role in lake metabolism at the upper end of the trophic scale. In general, however, our knowledge of the microbial ecology of hypertrophic systems has advanced very little since the 1980s, largely because most studies of these systems have focused on their remediation.

The relationship between autotrophic picoplankton (APP) - the smallest autotrophic component of food web and the trophic status and the depth of lakes

The occurrence and dynamics of autotrophic picoplankton (APP) in relation to the trophic status of a lake is discussed basing on results from 9 lakes situated in northeastern Poland and southern Finland. The lakes varied in the concentration of basic nutrients, chlorophyll a, phytoplankton biomass, pH depth and the composition of APP.A positive relationship between the productivity of the lakes and the APP biomass was confirmed. Shallow lakes were characterised by a significantly higher abundance and biomass of APP than deeper lakes, regardless of their trophic status. The abundance of APP as well as its contribution to the total phytoplankton biomass in the studied shallow lakes was also higher, than it could be expected from the level of basic nutrients in those lakes.Results imply that, when compared to deep lakes of a comparable trophic level, shallow and occasionally turbid water environment may create favourable conditions for APP, enabling it to occur in high numbers and thus influence the carbon cycling causing an increase of the carbon flow through the microbial food webs.

Phytoplankton community structure in non-stratified lakes of Pomerania (NW Poland)

The species composition, abundance and biomass of autotrophic picoplankton and larger phytoplanktonic organisms were analysed in 17 non-stratified lakes of Pomerania. Water samples were collected in August in 1995–1999. The composition and structure of phytoplankton varied among the lakes. Two groups of lakes could be distinguished: with a low and with a high species richness. Phytoplankton abundance ranged from about 1 × 102 to 1.5 × 106 cells ml−1 and was usually dominated by green algae, cyanobacteria, chrysophytes and dinoflagellates. Phytoplankton biomass ranged from 0.04 to 16.9 mg l−1 and in half of the lakes was dominated by cyanobacteria or dinoflagellates. Biomass of the smallest size fraction i.e. autotrophic picoplankton (APP) was always small in comparison with that of larger phytoplanktonic organisms. Cyanobacterial cells were usually the main components of APP, while eukaryotic APP were rare. Colonial forms accounted for 6–93% of the total APP abundance. In terms of total phytoplankton biomass, organisms from one of the other fractions, i.e. nanoplankton or microplankton, were usually more important. As the community structure of phytoplankton showed clear differences among lakes, special attention was paid to the variation in the relative abundance and biomass of some species or groups of species.

Picoplankton dynamics in a hypertrophic semiarid wetland

This study was carried out on a neglected component of wetlands: the picoplankton community. We analyzed the picoplanktonic community patterns and their related environmental factors in a hypertrophic semi-arid wetland located in Central Spain (Las Tablas de Daimiel National Park, TDNP). We determined the bacterial and autotrophic picoplankton (APP) abundance over a three-year period (1996: the end of a long drought period and 1997–1998: after flooding) in five sites of the wetland. The overall range of bacterial abundance was 0.2 × 106 to 10 × 106 cells/ml. The annual mean abundance increased in the wettest 1997. APP was composed mainly by coccoid phycocyanin-containing cyanobacteria, with the greatest abundance up to 25 × 105 cells/ml. The annual mean also increased considerably in wetter 1997–98. Despite the large APP biomass in some sites, its percentage of total phytoplankton biomass was low (the annual average did not exceed 1.5%). We observed spatial heterogeneity in the picoplankton fraction depending on the fluctuating hydrology: bacteria tends to spatial homogeneity after flooding while APP showed only similarity among the output sites. Among the considered predictive variables (temperature, phosphorus, nitrogen, zooplankton, phytoplankton) of the picoplanktonic dynamics, temperature was the most closely correlated to picoplankton, especially to bacterial abundance. Further, in two factorial, coupled-hierarchical laboratory experiments (constant temperature), we searched for control mechanisms of picoplankton. We tested (a) the trophic cascade hypothesis by analyzing the effect of presence/absence of mosquitofish (experiment 1) or directly modifying the zooplanktonic community (experiment 2) and (b) the bottom-up regulation by altering the nutrient conditions (presence/absence of sediment in experiment 1; reducing the nutrient content in experiment 2). Bacterioplankton failed to show any behavior related to trophic cascade direct effects, while nutrients increased its abundance. APP was affected positively by nutrients and negatively by zooplankton grazing.

Composition and dynamics of autotrophic picoplankton and spectral light distribution in saline lignite mining lakes of Germany

In two saline turbid mining lakes, the seasonal dynamics of autotrophic picoplankton (APP) were investigated. APP biomass accounted for 10–96% (annual average 48%) of the total autotrophic biomass. Eucaryotic picoplankton was dominant during spring and autumn (0.4–9 10 7 cells l −1). Picocyanobacteria appeared from June to September, reaching abundances of up to 1.3×10 8 cells l −1 . The total phosphorus content varied in the range 7–46 μg P l −1 and chlorophyll a (chl a) in the range 0.5–5.2 μg chl a l −1. The euphotic zone (1%-light level) extended only over the upper part of the epilimnion during the 1997 growing season. Red light (620–720 nm) was available within the water body. Blue or green light (430–580 nm) was mostly absent because of the high contents of suspended particles in lakes. This may be a reason for the occurrence of only phycocyanin-rich picocyanobacteria in the lakes investigated. This study shows that the APP constitutes a significant part of the phytoplankton in these slightly saline (6.5–8‰) turbid mining lakes. Because of their small cell size, higher uptake rates of inorganic nutrients and possibility of efficient utilization of low light intensities, they might have had an advantage for the development in the lakes investigated.

Composition and dynamics of autotrophic picoplankton and spectral light distribution in saline lignite mining lakes of Germany

Abstract In two saline turbid mining lakes, the seasonal dynamics of autotrophic picoplankton (APP) were investigated. APP biomass accounted for 10–96% (annual average 48%) of the total autotrophic biomass. Eucaryotic picoplankton was dominant during spring and autumn (0.4–9 107 cells l-1). Picocyanobacteria appeared from June to September, reaching abundances of up to 1.3 × 108 cells l-1. The total phosphorus content varied in the range 7–46 µg P l-1 and chlorophyll a (chla) in the range 0.5–5.2 µg chla l-1. The euphotic zone (1%-light level) extended only over the upper part of the epilimnion during the 1997 growing season. Red light (620–720 nm) was available within the water body. Blue or green light (430–580 nm) was mostly absent because of the high contents of suspended particles in lakes. This may be a reason for the occurrence of only phycocyanin-rich picocyanobacteria in the lakes investigated. This study shows that the APP constitutes a significant part of the phytoplankton in these slightly saline (6.5–8%) turbid mining lakes. Because of their small cell size, higher uptake rates of inorganic nutrients and possibility of efficient utilization of low light intensities, they might have had an advantage for the development in the lakes investigated.

The significance of autotrophic and heterotrophic picoplankton in hypertrophic ecosystems

Hypertrophic aquatic ecosystems are biologically important because they represent an environment where homeostatic mechanisms are strongly reduced and extreme oscillations occur in physical and chemical parameters as well as in the growth of many planktonic organisms. Hypertrophic lakes may represent not only the ultimate state of eutrophication, but also systems where abundance and production of picoplanktonic organisms (0.2–2 μm in diameter) may theoretically be greatest. In this review we examined the microbial ecology literature for studies on hypertrophic lakes and assessed the significance of heterotrophic bacteria (BACT) and autotrophic picoplankton (APP). Our main conclusions are as follows: (a) The relative contribution of APP to total phytoplankton biomass is strongly reduced in hypertrophic systems. (b) The absolute abundance and biomass of APP are highly variable among these systems; depending mainly on differences in light quality and quantity, the existence of nitrogen limitation and presence of pollutants. (c) The abundance of BACT does not increase as rapidly as algal biomass with increasing trophy. (d) A clear dichotomy exists between lakes dominated by Microcystis where bacterial biomass and production are relatively low, and Planktothrix-dominated lakes where bacterial biomass and production are high. (e) Bacterial production per unit biomass tends to increase from oligotrophic to hypertrophic systems supporting the previous hypothesis that bacteria do not play a lesser role in lake metabolism at the upper end of the trophic scale. In general, however, our knowledge of the microbial ecology of hypertrophic systems has advanced very little since the 1980s, largely because most studies of these systems have focused on their remediation.

Population dynamics of autotrophic picoplankton in a southeastern U.S. Reservoir

AbstractReservoirs typically exhibit a gradient along their longitudinal axis in turbidity, nutrient flux, and algal biomass. We utilized these characteristics to examine factors influencing temporal and spatial patterns in abundance, biomass, composition, and production of epilimnetic autotrophic picoplankton (APP) in Sardis Reservoir, Mississippi, USA. Over a 18‐month period, APP abundance varied between about 15,000 and 700,000 cells ml−1. Both APP abundance and APP biomass were closely linked to APP production and temperature. On an annual basis, the contribution of APP to total algal biomass and light‐standardized production ranged between 15–47%, and 5–40%, respectively. Prokaryotes comprised more than 95% of all APP in summer, but eukaryotes dominated the APP community in winter. During the nutrient‐depleted summer period, APP decreased in number but tended to increase in the percentage of total algal biomass and production, from the uplake riverine zone to the downlake lacustrine zone. Only in the second year of the study, when reservoir water residence time was more than four times greater than in the first year, were there significant differences in biomass and productivity of APP between the uplake and downlake regions. We suggest that, particularly in years or at times of the year when water‐flow through the reservoir is slow, the importance of APP in Sardis Reservoir reflects a spatial and temporal gradient in nutrient availability.