Seasonal Succession Of Phytoplankton Research Articles

Seasonal succession of phytoplankton in the eutrophic Lake Bled

Seasonal succession of phytoplankton in the eutrophic Lake Bled

Comparison of phytoplankton succession in two lakes of different mixing regimes fig: 12 tab: 4

The influence of frequent water-column mixing on phytoplankton succession and species composition was studied by comparing plankton dynamics in two lakes (Lake Opinicon and Upper Rock Lake) which have similar water chemistry, but differ widely in their basin morphometries: Opinicon is shallow and frequently-mixed during the ice-free season, whereas nearby Upper Rock is deep and dimictic. The species composition and the seasonal succession of phytoplankton were broadly similar in both lakes over the three years of study. The spring phytoplankton in both lakes consisted of diatoms that were replaced in the summer and fall by cyanobacteria. Diatom peaks in Opinicon preceded similar peaks in Upper Rock. Loss of diatoms from the phytoplankton in Upper Rock appeared to be related to sedimentation; in contrast, zooplankton herbivory may have resulted, partly, in loss of diatoms in Opinicon. Lightly-silicified and spindle-shaped diatoms (Rhizosolenia and single-celled Fragilaria) were more abundant in the dimictic lake, whereas heavily-silicified diatoms (Aulacoseira) were more abundant in the frequently-mixed lake. Zooplankton taxa and their seasonal patterns were similar in both lakes, but populations were considerably denser in the frequently-mixed lake. The results of canonical correspondence analysis and detrended correspondence analysis (multivariate ordination techniques) indicated that, although phytoplankton growth was influenced by similar physical and chemical variables in both lakes, the influence of chemical variables was stronger in Upper Rock. A frequently-mixed system, such as Lake Opinicon, appeared to provide a similar environment for plankton development to a well-mixed epilimnion of a typical dimictic lake, such as Upper Rock Lake.

Zooplankton-phytoplankton interactions: a possible explanation of the seasonal succession in the Kuršių Marios lagoon

The zooplankton-phytoplankton interactions inthe Kursių Marios lagoon (southeastern Baltic Sea)were investigated in 1995. The objective was toevaluate the role of herbivores (crustaceanzooplankton) in the seasonal succession ofphytoplankton, as well as the influence of foodconditions on structure and dynamics of zooplanktoncommunity. Our results demonstrated that thecrustacean grazing pressure may restrict thedevelopment of small Chlorophyta and Diatomophyceaeand, in turn, favouring growth of Cyanobacteria.Blooms of filamentous Cyanobacteria possibly has aninhibitory effect for Daphnia, decreasing theirbiomass as well possibly explaining the shift ofdominant zooplankton species. The influence ofplanktivory on seasonal plankton succession remainsunclear because of lack of fish data.

A modelling study of Emiliania huxleyi in the NE atlantic

Intensive (> 10,000 cells ml−1) and extensive (> 100,000 km2) blooms of the coccolithophorid Emiliania huxleyi frequently occur in the NE Atlantic, usually in the months of June and July, and only north of 50°N. This article describes a modelling study of these blooms, with the aim of understanding why they occur. That is to say, which water conditions allow Emiliania huxleyi to become dominant amongst the phytoplankton? Providing answers to these questions in the NE Atlantic, and comparing the results with data from other areas, allows us to tackle the question: what is the ecological niche for Emiliania huxleyi? The model described in this article is a single-layer ID Eulerian phytoplankton seasonal succession model, with detailed representations of physical, chemical and biological forcing functions and interactions. Model assumptions and their derivation from data are described, and sensitivity analyses examine the reliance of model results on individual assumptions. The model results suggest that, in the summer of 1991 in the NE Atlantic, the most likely factors causing the bloom of Emiliania huxleyi were high light (high surface irradiances, shallow stratification) and low phosphate (phosphate limiting rather than nitrate). The model was able to reproduce the observed distributoin of Emiliania huxleyi in the NE Atlantic by assuming that Emiliania huxleyi has similar limitations to other phytoplankton species except that it possesses a competitive advantage at high light and low phosphate.

Glutamine Synthetase activity in limnetic phytoplankton

The seasonal distribution of potential Glutamine Synthetase (GS) activities was studied in eutrophic Lake Aydat (France, Massif Central). The validity of this index of N-assimilation in field studies was tested by a comparison with the coupling of distributions of inorganic nitrogen uptake rate based on14C incorporation into proteins and the amino acids to protein ratio together with several abiotic and biotic parameters. The potential GS activities recorded during the seasonal succession of phytoplankton (characterized by the dominance of diatoms) were in the same order of magnitude of those reported from the very poor literature on this subject. Over high N-NO 3 - availability, the potential GS activities recorded were close to indirect estimations of N-uptake rates. During nitrogen depletion, high potential GS activities (which coincided with a development of small diatoms) were recorded suggesting that cell metabolism adapted to N-nutrient constraints. In addition, potential GS activity evolved concomitantly to other indicators of N-uptake and N-status. However, N-assimilation rates based on the enzymatic approach were lower than those obtained through indirect isotopic determination of uptakes rates. We suggest therefore that GS was not the unique pathway of ammonium assimilation in field populations.

Direct and indirect effects of grazing on the phytoplankton seasonal succession in an oligotrophic lake

We examined the simultaneous dynamics of phytoplankton and zooplankton in an oligotrophic lake, as well as the algal response to experimental manipulations of herbivore population structure and density. The seasonal succession of phytoplankton is characterized by a shift in dominance from eukaryotic species to prokaryotic cyanobacteria, as in a eutrophic lake. This unusual pattern for an oligotrophic lake is related to the release of zooplankton phosphorus, rather than to the amount of total phosphorus. The highest estimated values of this released phosphorus occur during the co-dominance of small-sized species and of one calanoid population, both under natural and experimental conditions. Our experimental results clearly reveal that a blue-green species replaces non-blue-green ones when environmental conditions render low or intermediate values for released phosphorus, irrespective of the grazing pressure. The absence of predators or high levels of released phosphorus stimulate non-blue-green growth. These results agree with the successional pattern observed for the algal assemblage under natural conditions. Nutrient recycling plays an essential role in the maintenance of the metabolism of the pelagic system, and therefore the prevalence of a topdown regulation mechanism as proposed for such low-nutrient environments should be reconsidered.

Optimal foraging by a suspension-feeding copepod: responses to short-term and seasonal variation in food resources

Laboratory radioisotope experiments were used to investigate the effects of phytoplankton seasonal succession on the selectivity and clearance rates of a suspension-feeding copepod in two Indiana lakes. Responses to particle size and quality were tested by allowing adult female Diaptomus birgei feeding in natural seston to select between a small (6×7 μm) flagellate (Chlamydomonas reinhardii) and a large, poor quality food (heat-killed Carteria olivieri, 22×25 μm). Short-term responses were tested in one lake by additional treatments in which copepods were acclimated for 5-6 h in filtered lake water ("starved") or natural seston with added Chlamydomonas ("enriched"). Copepods from both lakes fed selectively on the small live flagellate during the spring bloom of edible phytoplankton but fed selectively on the larger, poor quality particle during the "clear water phase" when food was scarce. These results are interpreted as an interaction between the concentration-dependent selectivity for high quality foods predicted by optimal diet theory and a perceptual bias for large-sized particles. Selectivity for high-quality food was intermediate and clearance rates were depressed when total phytoplankton abundance was high but dominated by filamentous cyanobacteria. In each experiment copepods also responded to the short-term manipulations by exhibiting weaker discrimination against the poor quality particle in the starvation treatment and stronger discrimination in the enriched treatment. A two-way mixed model ANOVA revealed substantial short term (37%) and seasonal (53%) components to the total variance in selectivity. Clearance rates were also influenced by both phytoplankton succession and the short-term resource manipulations. As expected, clearance rates on the poor quality food were more sensitive to the abundance of alternative foods. These results show how the feeding behavior of a freshwater copepod is modulated by both seasonal and short-term variation in natural food.

Production of allelochemicals in Fischerella muscicola under different environmental conditions

The existence of allelopathic interactions among phytoplankton species remains controversial (for review see RICE 1984). Even if allelochemicals can be isolated, their action in the ecosystem, e.g. on phytoplankton seasonal succession, remains debatable. The question is whether they are released or actively excreted into the environment and what concentrations are necessary to be effective in the waterbody. A major problem relates to the large distances water-soluble allelochemicals have to move to reach target organisms in the phytoplankton communities (LEWIS 1986). On the other hand, reports on the isolation of allelochemicals from benthic cyanobacteria have been published in recent years (MASON et al. 1982, MOORE et al. 1984). We studied the allelopathic potential of the benthic cyanobacterium Fischerella muscicola, that strongly inhibits other cyanobacteria (FLORES & WOLK 1986) and to a lesser extent members of the chlorophytes and diatoms. We isolated the main active compound by a bioassay direeted extraction proeedure, purified it and ealled it fiseherellin. Results of the physieal and ehemieal eharaeteristies of fischerellin and its physiologieal role have been published recently (GROSS et al. 1991). Studying allelopathie interaetions in benthie eyanobaeteria is promising for several different reasons: many eyanobaeteria are known to produee a great number of different seeondary metabolites (MOORE 1981). Sueh eompounds are often investigated for pharmaeeutieal purposes, although they mayaIso have an eeological and physiologieal role. Additionally, in benthie and edaphic habitats allelopathy seems to be a powerful competitive strategy beeause of the proximity of adjaeent speeies. We suggest that eertain alleloehemieals are transmitted by direet contaet of eells for whieh purpose lipophilie inhibitors of low moleeular weight would be very suitable. As F. muscicola is able to kill algae growing adjacently, we studied the excretion and transfer of fischerellin. In this eontext it is also important that the quality and quantity of alleloehemieals produced might depend on environmental conditions, e.g. the strength of eompetition, nutrient depletion or shading (BOYER et al. 1987). Aecordingly, we studied fischerellin production by F. muscicola experimentally under nitrate, phosphate and light limitation. Materials and methods

Gravel-Pit Lakes Connected with the River Rhine as a Reserve for High Productivity of Plankton and Young Fish

During the last two decades an increasing number of sand and gravel-pits were established in the original flood plain of the River Rhine. Some of these are connected with the stream by a small canal for the transport of the spoil. Some of these dredged lakes have been studied during recent years at the ecological field station of the University of Köln, with regard to seasonal phytoplankton succession, productivity of copepods and cladocerans, occurrence of macrozoobenthos, and both spawning and recruitment of fish populations. These eutrophic lakes represent a valuable substitute biotope for lost lentic waters of the former flood plain. They offer via the canal connection an advantageous habitat to resident fish species of the Lower Rhine, (1) for reproduction and growth of the 0+-generation, and (2) for shelter during flood events. Recommendations for reclamation plans of such lakes are required.

Seasonal succession of phytoplankton in a lake of the Paraná river floodplain, Argentina

Phytoplankton biomass, morphological and taxonomic composition, species diversity and productivity were analyzed in a shallow lake of the Middle Parana River floodplain (El Tigre, 31 ° 41′ S and 60° 42′ W), between November 1986 and July 1988. Lake inundation (filling and through-flow phases) constituted an intense long-term perturbation in the physical and chemical environment. As the lake filled with river water, K-selected species (netplanktonic filamentous bluegreens, > 37 µm, with low surface area/volume (SA/V) ratios) that had existed prior to filling (late spring 1986) were replaced in summer-fall by r-selected species (nannoplanktonic chlorophytes and cryptophytes, < 37 µm, mainly stout forms with high SA/V ratios). During the through-flow phase, lentic phytoplankton was replaced by lotic flagellate populations due to the direct flushing by river water. During the period of falling water (drainage and isolation phases), nanoplanktonic algae with similar characteristics to those of the filling phase dominated in late winter-spring. Later in the isolation phase, these were succeeded by K-selected species (netplanktonic algae, mainly motile spherical dinoflagellates and filamentous bluegreens with low SA/V ratios). Simultaneously, primary production per unit biomass decreased and total biomass and specific diversity increased. Seasonal changes of phytoplankton in floodplain lakes can be interpreted as the interaction between true successional development (as observed in the drainage and isolation phases) and intermediate disturbance. Using Reynolds' terminology, short-term disturbance (slight inflow of nutrient-rich river water) caused ‘reversion’ to an earlier stage in the former succession, and long-term disturbance (lake inundation) truncated the successional progression and a new (or ‘shifted’) succession was initiated.

Seasonal succession of phytoplankton in a small Andean patagonian lake (Rep. Argentina) and some considerations about the PEG Model

Seasonal succession of phytoplankton in a small Andean patagonian lake (Rep. Argentina) and some considerations about the PEG Model

Seasonal succession of phytoplankton and its diversity in two highly eutrophic lakes with different conditions of stratification

Seasonal succession of phytoplankton and its diversity in two highly eutrophic lakes with different conditions of stratification

Seasonal Changes in the Plankton Dynamics of a Eutrophic Lake Including the Microbial Web

AbstractDuring 1989 and 1990 the carbon dynamics in the shallow eutrophic Lake Müggelsee (Berlin) were investigated by analysing the seasonal succession of phytoplankton, metazooplankton, protozooplankton and bacteria. Size fractionated algal primary production and exudation were measured as well as bacterial production in order to calculate the amount of carbon covering the bacterial carbon demand by primary production. The impact of bacterivorous protozoans and metazoans was estimated by comparison of the calculated feeding rate and the bacterial production. Our results show a shift within the metabolic interactions of the microbial food web from winter/spring to summer, indicating a high significance of the protozooplankton as a regulator on bacteria during the colder season, whereas from early summer the influence of metazooplankton dominated by cladocerans was evident in this eutrophic lake.

Seasonal pattern of ammonium (methylamine) uptake by phytoplankton in an oligotrophic lake

Our primary objective was to determine if a relationship existed between seasonal change in phytoplankton and high affinity for (Km) or uptake rates (VmaX) of ammonium which might explain seasonal phytoplankton succession in oligotrophic ecosystems. We measured ammonium uptake using [14C]-methylamine and estimatedKm andVmax using Hanes Plots at 2-week intervals during 6 months of thermal stratification in Mountain lake, Virginia (37° 22′ N, 80° 32′ W). Community composition, nutrient levels, and other variables were determined in all uptake experiments. A second objective was to determine if ammonium was preferentially utilized over nitrate and to characterize further the ammonium transport system.Vmax increased steadily from May until the end of July, each increase coinciding with major changes in the phytoplankton community. Cryptophyceans dominated in May, chlorophyceans in June and July, and cyanophyceans from the end of July to late October. With cyanophycean dominance,Vmax declined until chlorophyceans reestablished dominance in late October. By contrast,Km values increased from May to the end of July, but thereafter showed no correlation. Acetylene reduction experiments showed no nitrogen fixation during late summer and fall when blue-green algae were present. Preference for ammonium was implied also by negative nitrate reductase assays. Overall, the coincidence ofVmax andKm values for [14C]-methylamine uptake and changing phytoplankton community structure suggests the possibility that successive algal communities may be changing as a result of specific species differences in ammonium affinity and uptake rates.

Seasonal Succession of Phytoplankton in a Large Shallow Lake (Balaton, Hungary)--A Dynamic Approach to Ecological Memory, Its Possible Role and Mechanisms

The phytoplankton of the large shallow Lake Balaton was studied quantitatively on 211 consecutive days between April and November 1980. In total 417 taxa were found during the period of sampling. The number of planktonic species was c.300. Compared with the few dominants, most of the species were extremely rare. Relative frequencies (RF) within the total number of enumerated specimens (c.100000) were used to analyse the quantities of both frequent and rare species on a common quantitative base. Approximately two-thirds of the 300 planktonic species were evenly distributed in time, the others exhibited temporal peaks (...)

The seasonal succession of phytoplankton in an eutrophic lake through the coupling of biochemical composition of particulates, metabolic parameters and environmental conditions

The seasonal succession of phytoplankton in an eutrophic lake through the coupling of biochemical composition of particulates, metabolic parameters and environmental conditions

Seasonal associations of phytoplankton and planktic foraminifera in an upwelling region and their contribution to the seafloor

Seasonal occurrences of both phytoplankton and zooplankton are closely associated with upwelling and stabilization in waters overlying the San Pedro Basin. This region is situated within the Southern California Bight and is affected by variations in the general southward flowing California Current and variable intrusion of oceanic waters. Increased northerly wind stress in spring and early summer results in upwelling of deeper, nutrient-rich waters into the photic zone. A seven month time-series sediment trap experiment revealed clear patterns in seasonal succession of both phytoplankton and planktic foraminifera. Several distinct high and low flux periods occurred over the study period, some of which can be related to rapid changes in the hydrographic environment caused by upwelling and subsequent surface water stratification. Factor analysis of relative abundances of combined phytoplankton and foraminiferal taxa defines seven assemblages reflecting seven stages of production which range in duration from two to five weeks. Factor scores describe phytoplankton and foraminiferal taxa indicative of specific production stages. Periods of high flux of the more abundant diatoms and planktic foraminifera also illustrate preferred production stages and compare well with percentage-based results. A comparison of the sediment trap assemblage with local sediment from an oxygenated portion of the basin suggests that long-term phytoplankton accumulation in this region is dominated by taxa associated with winter bloom and post-upwelling bloom production, implying that brief but massive episodic events overwhelm and dominate the annually averaged diatom species assemblage found in the sediments. Foraminifera, however, are modified by dissolution to the extent that the high production periods of late spring and during upwelling are poorly represented. Rather, species indicative of early spring and post-upwelling conditions dominate the planktic foraminiferal sedimentary assemblage.

The Concept of Seasonal Succession Theory Applied to Phytoplankton Through the Coupling Use of Diversity Index and Rank-Frequencies Diagrams in a Eutrophic Ecosystem

Seasonal succession of phytoplankton was studied in a eutrophic lake (Lake Aydat, Massif Central, France), from March to November 1985. An attempt is made to check the succession stages of the concept of ecological succession theory using either the H-diversity index of SHANNON and WEAVER or the FRONTIER'S rank-frequencies diagrams. A description of a stage 3 community was only possible through the use of the latter diagrams.

Lake Kinneret phytoplankton: Stability and variability during twenty years (1970?1989)

The general features of phytoplankton seasonal succession, abundance and distribution in Lake Kinneret, as based on observations from 1970 through 1989, are summarised. Throughout this period of observation, the large, thecate dinoflagellatePeridinium gatunense formed an annual, late winter to early spring bloom resulting in very high standing stock levels. The dominance of these dinoflagellates has a profound impact upon the lake ecosystem. In the summer and fall the phytoplankton assemblage consisted mainly of nanoplanktonic green and blue-green algae and diatoms. Picophytoplankton, mainly picocyanobacteria, were present in low numbers during the dinoflagellate bloom but reached maximum abundance (105 cells · ml−1) in the epilimnion during the summer and fall. Within a given year, chlorophyll concentrations correlated well with estimates of wet weight biomass, derived from microscope counts. However, interannual averages of chlorophyll did not correlate closely with those for wet weight biomass. Both wet weight biomass and chlorophyll standing stocks fluctuated more than 2 fold from 1970 through 1989 but no extreme, long-term, continuous trend of increase or decrease was observed. Thus, phytoplankton has remained relatively stable although there has been a significant rise in the levels of summer-fall biomass since 1981. The main factor responsible for this may have been increased available phosphorus; the abundance of phytoplankton did not show any clear, long-term relation to that of herbivorous zooplankton.

Effects of mixing and silica enrichment on phytoplankton seasonal succession

During the summer of 1983, cryptophytes, diatoms, cyanophytes, and the dinoflagellate, Ceratium hirundinella were most prominant among the phytoplankton of Eau Galle Reservoir. In the open water, cryptophytes and diatoms peaked in the spring, cyanophytes were most successful in the early summer, and Ceratium was dominant from mid-July until early August. In general, the sequence of events corresponded quite closely to the model of seasonal succession developed by the Plankton Ecology Group of the International Society of Limnology. To a large extent, the same pattern held in four experimental water columns. Departures from the model involved the roles of specific nutrients in diatom and cyanophyte periodicity. Diatoms began to yield to cyanophytes in late spring despite intermittent mixing and silica enrichment. Although capable of buoyancy regulation and thus well adapted to stable water columns, cyanophytes had greater increases in biomass in mixed columns, and in those columns, were most successful during a period of intermittent mixing. Cyanophyte success varied inversely with TN : TP ratios during the period of intermittent mixing, but not subsequently. By mid-July, Ceratium dominated the phytoplankton of every column except that of a mixed column in which conditions favored cyanophytes and large diatom species.