Development Of Phytoplankton Biomass Research Articles

Regular build-up of the spring phytoplankton maximum before ice-break in a boreal lake

The development of phytoplankton biomass and composition in a eutrophic boreal lake was studied during the evolution of under-ice convection in spring. The results from 8 yr showed that, within a few weeks before ice-break, phytoplankton biomass regularly increased by up to two or three orders of magnitude, reaching or exceeding the biomass in summer. Accordingly, this may be the most significant single annual phytoplankton episode in the lake. The development of phytoplankton was closely coupled with that of convection created by solar radiation at water temperatures < 4°C. In addition to vertical convection which keeps phytoplankton suspended, there was also horizontal convection which transported water with likely higher abundance of phytoplankton from the shallow lake margins. The effect of mechanical mixing, which was meant to prevent anoxia in the deep water layers of the study basin, was overridden by natural convection. Stochastic variations in weather played a key role controlling light penetration into the lake and hence the abundance and composition of under-ice phytoplankton. After snow melt the proportion of motile algae was at first higher, sometimes with a maximum nearest to the ice, but later diatoms flourished throughout the convection layer. Only in the years of the shortest convection period did the proportion of motile algae remain high until the end of ice cover. More detailed information about the interaction between littoral and pelagial water masses under different mixing regimes is needed for a more profound understanding of the development of phytoplankton under-ice.

Predicting phytoplankton biomass and estimating critical N:P ratios with piecewise models that conform to Liebig's law of the minimum

Summary The influence of nitrogen and phosphorus on the development of phytoplankton biomass is typically such that when one nutrient is limiting, variation in the availability of the other has little effect; this is known as Liebig's law of the minimum. However, statistical models used to quantify the dependence of phytoplankton biomass on both nitrogen and phosphorus availability have typically assumed multiplicative effects of the two nutrients. Here, we demonstrate that a new statistical model, which conforms to this law of the minimum, better describes the response of biomass to nitrogen and phosphorus and in addition provides an estimate of the ratio at which lake phytoplankton communities typically transition between nitrogen and phosphorus limitation. This improvement holds for three large independent sets of lakes, and we conclude that the previous mismatch between the nature of resource limitation and the models used to investigate it may have contributed to an underestimation of the influence of nitrogen on freshwater phytoplankton biomass.

Response of phytoplankton communities to salinity changes – a mesocosm approach

The response of natural phytoplankton communities, originating from oligohaline brackish water systems, to salinity changes (3–12 PSU) has been studied in small-scale mesocosms. Simultaneously, their reaction on iron manipulations was tested. The experiments, each lasting 7 days, were repeated three times at different dates. Treatments were evaluated with respect to biomass development (Chl a concentration), photosynthesis behaviour, and rough taxonomic composition. The investigated phytoplankton communities were dominated by cyanobacteria. Salt addition was not effective for overall phytoplankton biomass development. Filamentous cyanobacteria, however, were promoted by NaCl enrichments. Dark yield and non-photochemical quenching of fluorescence (NPQ) analyses revealed differences for treatments in dependence on iron supplements. Iron partially seemed to dampen the effects of salt shocks, and iron addition reduced both, capacity and irradiance dependency of NPQ, irrespective of the NaCl treatment.

Summer feeding activities of zooplankton in Prydz Bay, Antarctica

Grazing of dominant zooplankton copepods (Calanoides acutus. and Metridia gerlachei), salps (Salpa thompsoni) and microzooplankton was determined during the austral summer of 1998/1999 at the seasonal ice zone of the Prydz Bay region. The objective was to measure the ingestion rates of zooplankton at the seasonal ice zone, so as to evaluate the importance of different groups of zooplankton in their grazing impact on phytoplankton standing stock and primary production. Grazing by copepods was low, and accounted for less than or equal to 1% of phytoplankton standing stocks and 3.8-12.5% of primary production for both species during this study, even the ingestion rates of individuals were at a high level compared with previous reports. S. thompsoni exhibited a relatively high grazing impact on primary production (72%) in the north of our investigation area. The highest grazing impact on phytoplankton was exerted by microzooplankton during this investigation, and accounted for 10-65% of the standing stock of phytoplankton and 34-100% of potential daily primary production. We concluded that microzooplankton was the dominant phytoplankton consumer in this study area. Salps also played an important role in control of phytoplankton where swarming occurred. The grazing of copepods had a relatively small effect on phytoplankton biomass development.

Resuspension in regulating sedimentation dynamics in Lake Vesijärvi.

The role of resuspension in sedimentation dynamics and internal phosphorus (P) loading was investigated in the Enonselka basin of Lake Vesijarvi, southern Finland. The gross sedimentation rate was measured at three sampling sites, where sedimentation traps were placed 2 m above the bottom (the depth of 28 m, 18 m and 7m) and at the two deepest sites also in the metalimnion (11 m depth). The total settling flux did not follow either the phytoplankton biomass development in the lake or the bacterial mineralization rate in the settled material. The gross sedimentation rate was much higher in the hypolimnion than in the metalimnion, indicating that resuspension increased the settling flux. This conclusion is supported by the fact that when the gross sedimentation rate increased, the C and N concentrations of settled material resembled those of bottom sediment. The proportion of resuspended material, estimated by three different methods, averaged 56-99 % of the gross sedimentation rate during the study periods. Contrary to the common assumption, the Enonselka basin provides an example of successful restoration by biomanipulation in lakes with high resuspension.

Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. II. Phytoplankton species composition

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 18:55-65 (1999) - doi:10.3354/ame018055 Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. II. Phytoplankton species composition Per Carlsson*, Edna Granéli University of Kalmar, Department of Marine Sciences, POB 905, S-391 29 Kalmar, Sweden *E-mail: per.carlsson@ng.hik.se ABSTRACT: Development of phytoplankton biomass and species composition in northern Adriatic Sea natural plankton communities was investigated in 2 spring/summer (May and June) enclosure experiments. The enclosures (100 l plastic cylinders) were subjected to different concentrations/ratios of nitrate, phosphate and silicate in order to obtain a situation where one of these nutrients would limit phytoplankton biomass in different treatments. The initial phytoplankton community in both experiments was dominated by small (both by cell numbers and biomass) autotrophic flagellates. In the May experiment the small autotrophic flagellates made up more than 50% of the initial biomass; this was 95% in June. The duration of the experiments were 7 and 10 d, respectively. A surplus of nitrogen, phosphorus and silicon favored the development of some fast-growing diatoms. Phosphorus deficiency induced higher phytoplankton biomass than expected from Redfield ratios (Redfield 1958), probably due to fast recycling of phosphorus compared to nitrogen. Despite low silicon concentrations in the silicon-deficient treatments, growth of diatoms was high in the May experiment suggesting a low silicon demand for the dominating small diatom species. The diatom Rhizosolenia fragilissima was particularly favored under phosphorus-deficient conditions whereas under nitrogen deficiency another diatom (Chaetoceros sp.) increased in biomass. Small flagellates were favored by either nitrogen deficiency (May) or by silicon deficiency (June). The increasing dominance of small flagellates in the natural communities during the transition from spring to summer, together with decreasing concentration of inorganic nitrogen, indicates that shortage of inorganic nitrogen can be important for the structure of northern Adriatic phytoplankton communities in this period. KEY WORDS: Adriatic Sea · Phytoplankton species composition · Diatoms · Flagellates Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 18, No. 1. Publication date: July 16, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.

Photosynthetic pigment fingerprints as indicators of phytoplankton biomass and development in different water masses of the Southern Ocean during austral spring

The development of phytoplankton biomass and composition was investigated on three occasions along a longitudinal transect (6°W) between 60°S and 47°S from October 13 to November 21, 1992 by measurement of photosynthetic pigments with high performance liquid chromatography (HPLC). Measured accessory pigment concentrations were multiplied by conversion factors to derive the proportions of phytoplankton groups contributing to the biomass indicator chlorophyll a. Phytoplankton blooms developed in the Polar Frontal region (PFr) and were dominated (80%) by diatoms. Other groups contributing to the phytoplankton included prymnesiophytes, green algae, autotrophic dinoflagellates, cryptophytes, pelagophytes and micromonadophytes, and their distributions varied with time. In contrast, phytoplankton biomass remained low in the southern Antarctic Circumpolar Current (ACC) and was dominated by flagellates, particularly green algae and prymnesiophytes. Green algae contributed more to total biomass than in previous investigations, partly attributed to “Chlorella-like” type organisms rather than prasinophytes. Cryptophytes decreased during the investigation, possibly due to salp grazing. No bloom was observed at the retreating ice-edge, presumably due to strong wind mixing. Only a slight increase in phytoplankton biomass, composed primarily of diatoms, was found at the ACC-Weddell Gyre front. Cluster analysis revealed that different phytoplankton communities characterised the different water masses of the PFr and southern ACC; the history of different water masses in the PFr could be reconstructed on this basis.

Effect of concentrating the virus‐rich 2‐2nm size fraction of seawater on the formation of algal flocs (marine snow)

Particle aggregates &gt;0.5 mm in diameter (marine snow) are an important component of marine environments. Viruses are now recognized as active members of the marine microbial food web, infecting both planktonic primary producers and bacteria. The effect of adding material from the 2–200‐nm size fraction, concentrated from seawater with ultrafiltration, on the development of phytoplankton biomass and formation of algal flocs was examined. At higher concentrations of material in this size fraction (2.3 times enrichment with virus‐like particles), the buildup of phytoplankton biomass was initially delayed. After 8 d, these enrichments resulted in the formation and persistence of up to 5 times higher numbers of larger aggregates (≥ 1‐mm equivalent spherical diameter) concomitant with even higher phytoplankton biomass. Both the size distribution of algal aggregates and primary production can be affected by material in the size range of 2–200 nm containing large numbers of viruses.

Seston in a seasonally flooded lake of the central Changjiang River (China)

Seston was studied during inundation in a seasonally flooded lake of Changjiang River system (Lake Chenhu, Hanyang, P.R. China). Particulate organic matter (POM), particulate inorganic matter (PIM), particulate organic carbon (POC) and particulate organic nitrogen (PON) concentrations were highest upon initial inflow of river water, as a result of the riverine transport of allochthonous seston into the lake, and during the initial draining phase, coinciding with the postflood development of phytoplankton biomass and accumulation of detritus from the decomposition of the inundated vegetation grown during the preceding period of exposure. However seston concentrations were lowest shortly after the termination of flood inflow, presumably due to sedimentation and river water dilution. Seston food quality, based on POM: PIM, C: N and Algal-AFDW : POM ratios, was higher during the early high water phase than during the filling and draining phases.

Quantifying the impact of periphytic algae on nutrient availability for phytoplankton

SUMMARY. Recent laboratory studies demonstrate that periphytic algae growing on the sediment surface reduce nutrient availability in the overlying water. Consequently, periphytic algae may competitively reduce growth of phytoplankton. The aim of this study was to quantify the competitive impact of sediment‐attached periphytic algae on phytoplankton in the presence of all other factors simultaneously affecting nutrient dynamics in natural systems. In enclosure experiments, performed in three lakes of different productivity, the periphytic algal biomass was manipulated. When compared to enclosures with high biomass of periphytic algae, those with reduced biomass showed an increase in total phosphorus concentration in the water of 32–44%. Extrapolation of the experimental results to whole lakes predicts an increase in original total phosphorus concentration of between 1.5% and 8.0%. According to existing regressions between total phosphorus and phytoplankton chlorophyll, the potential increase in original phytoplankton biomass will be between 2.5% and 12.6%. With respect to the shallow parts of lakes, my results support the conclusions revealed from laboratory studies that periphytic algae have a significant impact on the phosphorus concentration in the overlying water. However, when considering whole‐lake dynamics, the competitive impact of periphytic algae on phytoplankton biomass development is probably of minor importance. Rather, the main competitive advantage of growing on the sediment surface, compared to in the water, may be the exclusive access to nutrients in the sediment.

Effects of turbulence on the development of phytoplankton biomass and copepod populations in marine microcosms

Effects of turbulence on the development of phytoplankton biomass and copepod populations in marine microcosms

Regulation of phytoplankton biomass in estuarine enclosures

During April, June/July and September 1986, phytoplankton biomass was followed in marine enclosures in the Roskilde Fjord, Denmark, manipulated by the addition of benthic suspension feeders, planktivorous fish, nutrients and contact to the sediment. During periods with high insolation and temperatures from 11 to 22 C, the manipulations caused marked changes in the development of phytoplankton biomass. Additions of Mytilus edulis reduced phytoplankton biomass to between 10 and 59 % of controls, whereas addition of nutrients raised phytoplankton biomass to an average of 256 % of controls. Generally, low growth rates of mussels were found in enclosures containing mussels alone. Addition of planktivorous fish and nutrients increased growth rates of mussels. During June/July, when inorganic nitrogen limited phytoplankton growth, autotrophic picoplankton (1 to 2 pm cell diameter) constituted 70 to 93 % of phytoplankton biovolume in enclosures containing mussels compared to 4 to 20 % in controls. The mussels reduced phytoplankton biomass by only about 50 % during this period, presumably due to low retention efficiency of the small cells. In April and September, however, when nitrogen did not control phytoplankton growth, picoplankton comprised 6 C and in September, benthic suspension feeders maintained chlorophyll levels below those in enclosures with no sediment contact. During April, only minor changes were recorded in the chlorophyll levels in the various enclosures, presumably due to the low temperature (0 to 4.5OC) and a phytoplankton population of decaying diatoms. Thus, several factors or combinations of factors controlled the phytoplankton biomass in the enclosures. The most important of these factors was the balance between nutrient input, phytoplankton size structure and the physiological state of the mussels.

Synuraceae (Chrysophyceae) in the Netherlands

Investigations of phytoplankton biomass development and species succession in the Oude Waal near Nijmegen revealed the importance of the Chrysophyceae (Table I).