Number Of Phytoplankton Species Research Articles

Phytoplankton species diversity control through competitive exclusion and physical disturbances

Competitive exclusion theory suggests that phytoplankton species number in an assemblage at equilibrium will be limited to the number of simultaneously limiting resources, generally three or fewer. However, natural phyto‐plankton assemblages usually exhibit high species diversity, hence the concept of Hutchinson's “paradox of the plankton”. Recent works have suggested that this apparent paradox is a result of disturbances intermediate in frequency relative to the time period necessary for species succession to lead to equilibrium conditions (sensu Connell's intermediate disturbance hypothesis [IDH]). Moreover, evidence indicates that disturbances of intermediate intensities are also conducive to maintenance of high species diversity in phytoplankton communities. Using a long‐term data record from hypereutrophic subtropical Hartbeespoort Dam (South Africa) that was typically dominated by a single species, but annually subjected to physical disturbance, we demonstrate here that disturbances can indeed enhance phytoplankton species diversity. However, these data fail to support Connell's IDH per se, as moderate‐and high‐intensity disturbances yielded similarly high species diversity. These data also suggest that community resilience (the ability or time to return to predisturbed conditions) is negatively related to disturbance intensity, such that higher intensity disturbances maintained high diversity for longer periods of time relative to lower intensity disturbances.

Seasonal dynamics of plankton in a mountain lake in the southern Alps (Laghetto Inferiore, Switzerland)

The pelagic populations in Laghetto Inferiore (southern Swiss Alps) were studied between 1996 and 1998 during the ice-free period. Investigations revealed a considerable number of phytoplankton species but few zooplankton species. The vertical distribution of the main species of algae shows a marked vertical stratification, with higher biomass concentrations in the deep zone. Along this profile, species in the same taxonomic class tend to be distributed at different depths, according to their specific light requirements. During the study period no clear seasonal succession of populations was observed, also because of the influence of precipitation on the biological cycles. On the whole there was a good correspondence between the biomass values of phytoplankton and those of chlorophyll-a, both in integral samples of the whole water column and in the vertical profile.

The role of C, N and P in dissolved and particulate organic matter as a nutrient source for phytoplankton growth, including toxic species

Phytoplankton have traditionally been regarded as strictly phototrophic, with a well defined position at the base of pelagic food webs. However, recently we have learned that the nutritional demands of a growing number of phytoplankton species can be met, at least partially, or under specific environmental conditions, through heterotrophy. Mixotrophy is the ability of an organism to be both phototrophic and heterotrophic, in the latter case utilizing either organic particles (phagotrophy) or dissolved organic substances (osmotrophy). This finding has direct implications for our view on algal survival strategies, particularly for harmful species, and energy- and nutrient flow in pelagic food webs. Mixotrophic species may outcompete strict autotrophs, e.g. in waters poor in inorganic nutrients or under low light. In the traditional view of the ‘microbial loop’ DOC is thought to be channeled from algal photosynthesis to bacteria and then up the food chain through heterotrophic flagellates, ciliates and mesozooplankton. Are mixotrophic phytoplankton that feed on bacteria also significantly contributing to this transport of photosynthetic carbon up the food chain? How can we estimate the fluxes of carbon and nutrients between different trophic levels in the plankton food web involving phagotrophic algae? These questions largely remain unanswered. In this review we treat evidence for both osmotrophy and phagotrophy in phytoplankton, especially toxic marine species, and some ecological implications of mixotrophy.

Environmental hazards of nitrogen loading in wetland rice fields

Rice is the predominant crop in South and Southeast Asian countries, covering an area of 73.7 million ha. It is unique among the major food crops that, it grows well on flooded soil. When applied under flooded condition nitrogen, a major nutrient is prone to different types of losses, which are as high as 60%. With the increase in area under modern rice varieties in different countries, the usage of chemical fertilizer has been increased up to as high as 150 kg N/ha. About 10% of the total nitrogen fertilizer used globally are applied to rice. Chemical fertilizers supply nitrogen in ammonia, nitrate or amide forms. Among the N-fertilizers, about 80% of the demand are met by urea, which is highly water soluble and prone to losses. When any N compound is applied to a submerged paddy field, it is lost through leaching, denitrification, volatilization and runoff. Of the total N loss, leaching contributes about 30–50%, mostly as nitrate, denitrification, about 10–30% as N 2 and volatilization, about 2–30% as ammonia. The escaped nitrogen causes pollution to the atmosphere and water systems. In the lowlands, a dual rice-fish culture is also practised, where loading of high dose of nitrogen can be lethal to the fish. Studies have shown that nitrogen when applied in the form of ammonium sulfate was more lethal than urea. About 50% of the fish, Catla catla (common carp) were killed when ammonia concentration reached 29.4 mg NH 3-N/L. The fish growth was higher under organic based than inorganic based nitrogen fertilizers. The number of phytoplankton species, which are fish food, was also less when chemical fertilizers were used as a nitrogen source. Besides, it is expected that the leached NO 3-N may pollute the groundwater. Thus loading of nitrogenous compounds in rice ecosystems creates an unavoidable continuum of environmental hazards in rice growing countries.

UV‐induced changes in phytoplankton cells and its effects on grazers

1. This review addresses the effects of UV‐radiation on the morphology and biochemistry of phytoplankton and the potential effects on grazers.2. UVA and UVB radiation inhibit the uptake of inorganic nutrients in phytoplankton. Reduced rates of ammonium and nitrate uptake in marine diatoms, and reduced uptake of phosphorus in freshwater flagellates are reported. The effects on cell stoichiometry are not settled.3. UVA and UVB radiation promote increased cell volumes owing to a decoupling between the photosynthetic processes and cell division. Loss or inactivation of flagellae and loss of motility are also reported for a number of phytoplankton species.4. UVA and UVB radiation may affect major biochemical constituents. Accumulation of intracellular, photosynthetic products (lipids or carbohydrates) is a common, although not unique, property of UV‐stressed algae. Fatty acid (FA) profiles seem susceptible to UV radiation. A relative increase of short‐chained, and a decrease in polyunsaturated FA (PUFA) are reported. The important membrane FA like eicosapentaenoic acid (EPA, 20 : 5ω3) and docosahexaenoic acid (DHA, 22 : 6ω3) seem particularly susceptible, owing to lipid peroxidation or reduced biosynthesis.5. UV‐related responses are highly dependent on taxonomy, cell‐cycle stage, nutrient‐limitation and the UV : PAR (photosynthetic active radiation)‐ratio.6. Nutrient deficiency, cell size, cell wall properties and FA can all have significant impacts on grazers. Thus the reported effects on cell morphology and biochemical constituents could have profound effects on grazers and energy transfer in aquatic foodwebs.

Impact of acidification on structural organization of phytoplankton community in the forest lakes of the north-western Russia

The response of the phytoplankton to different degree of pH was studied by the example of 7 shallow weakly mineralized forest lakes located in the Darwin National reserve on the north shore of the Rybinsk reservoir (north-western Russia). With a decrease of pH the number of phytoplankton species decreased especially among centric diatoms,blue-greens and Euglenophyta, total biomass of phytoplankton and its seasonal dispersion declined. Green algae, chrysomonades and cryptomonades biomass correlated negatively with pH but diatoms and blue-greens biomass were related positively to pH. The drop in pH produced a decrease of Shannon-Weaver diversity index, obtained from biomass and cell volume of algae, increase of Simpson index and algae size. The growth of phytoplankton did not correspond the total phosphorus. The necessary modifications to the structural characteristics of phytoplankton by the acidification came about in the pH range from 6 to 5.

Impact of acidification on structural organization of phytoplankton community in the forest lakes of the North-Western Russia

The response of the phytoplankton to different degree of pH was studied by the example of 7 shallow weakly mineralized forest lakes located in the Darwin National reserve on the north shore of the Rybinsk reservoir (north-western Russia). With a decrease of pH the number of phytoplankton species decreased especially among centric diatoms, blue-greens and Euglenophyta, total biomass of phytoplankton and its seasonal dispersion declined. Green algae, chrysomonades and cryptomonades biomass correlated negatively with pH but diatoms and blue-greens biomass were related positively to pH. The drop in pH produced a decrease of Shannon-Weaver diversity index, obtained from biomass and cell volume of algae, increase of Simpson index and algae size. The growth of phytoplankton did not correspond the total phosphorus. The necessary modifications to the structural characteristics of phytoplankton by the acidification came about in the pH range from 6 to 5.

Effects of arsenate and copper on the algal communities in polluted lakes in the northern parts of Sweden assayed by PICT (Pollution-Induced Community Tolerance)

The tolerance for arsenate and copper in the carbon dioxide fixation activity of phytoplankton communities coming from lakes around the smelter at Ronnskar at the Swedish east-coast were measured during three years (1989–1991). The smelter have for several decades discharged arsenic and heavy metals into the air, and their concentrations in the lakes were clearly correlated with the distance from the smelter. The tolerance of communities from the three most polluted lakes were higher than communities from reference lakes with background concentrations of arsenic and copper. In accordance with the PICT concept it is indicated that those communities have been affected by these substances. These communities also had lower diversity than the others, but no clear correlation could be done with phytoplankton species number, or between phytoplankton biomass and pollution levels.

Phytoplankton functional attributes along trophic gradient and season

Each of the following phytoplankton functional attributes could be described by significant (P < 0.05) response surfaces defined by trophic status (T) from oligotrophy to hypertrophy and season (S) from early vernal period to late summer: phytoplankton cell volume, growth rate, the ratio between minimum quotas of total N and total P, affinity for P, half‐saturation constant for growth with respect to P, and temperature optimum and light optimum for growth. Sinking rate could not be so described. The response surfaces were calculated by multiple regressions, including first‐ and second‐order terms of T and S and the interaction term T · S. Although the data base was rather limited (number of phytoplankton species ranged from 10 to 31), the resulting surfaces often reflected a corresponding attribute of the water along T and S (e.g. phytoplankton temperature optimum for growth reflected water temperature). The results support the frequent use of physical factors as explanatory variables for the distribution and abundance of phytoplankton.

Chemical, biological and socio-economic approaches to the liming of Lake Alinenj�rvi in southern Finland

The aim of this comprehensive study is to estimate the effects and usefulness of liming Lake Alinenjarvi based on chemical, biological and socio-economic studies. Methodological standpoints concerning the limestone dissolution rate, acidic surges and reacidification are also discussed. L. Alinenjarvi (0.4S km2) is located near the city of Nokia with a surrounding population of over 5 000 (< 2 km). Before liming, the lake had only a sparse crayfish (Astacus astacus L.) population left, because reproduction had been failing since the early 1980s. The most important effect of liming is that it should connect with the potential production of crayfish. The roach (Rutilus rutilus L.) population was also affected. The liming improved the chemical quality of the water, and decreased also the Al and Mn concentrations. The number of phytoplankton species increased, and the species composition of periphyton changed after liming. The a-chlorophyll concentration in water remained low. Furthermore, crustacean zooplankton and benthic animals increased in abundance in the first late summer after liming. The diet analysis of perch (Perca fluviatilis L.) gave comparable results suggesting a possible positive effect of liming on their food resources. The improved water quality seems to make the reproduction of the crayfish possible again, but recovery would take several years. To guarantee a recovery, the introduction of new crayfish individuals and supplementary neutralizing methods would be needed. The results of a mailed survey showed that L, Alinenjarvi is a valuable water source for the local people. The most usual forms of leisure around the lake and shores are, however, outdoor recreation and swimming, with only minor usage for fishing. Despite that, though the immediate benefits would be negligible, a majority of local residents supported the continuation of liming even though they would have to carry the costs in the future.

Biological recovery of two previously acidified, metal-contaminated lakes near Sudbury Ontario, Canada

Studies are reported on two small lakes at Sudbury, Ontario located close to a nickel-copper smelter which closed in 1972. At that stage, Baby Lake had a pH of 4.0–4.2 while the adjacent Alice Lake had a pH 5.9–6.3. Both lakes were almost entirely devoid of algae and had neither Zooplankton nor fish. Soon after the closure of the smelter, with its large airborne volume of sulphur dioxide and of copper and nickel containing particulates, the chemistry of the lakes began to change. By 1985, Baby Lake had changed from pH 4.0 to 6.8 and is now at pH 7.2. The pH of Alice Lake increased from a low of 5.9 in the early 1970s to 6.9–7.4 in the mid 1980s and is now at 7.3. Copper and nickel concentrations also decreased in both lakes during this period. The first biota found in the lakes in the post-smelter stage in the early 1980s were benthic red chironomids, planktonic rotifers, and a limited number of phytoplankton species, of which Rhizosolenia was the most common. By the 1990s, 13 phytoplankton species were present in each lake, with a substantial Zooplankton fauna (14 species) of rotifers, copepods, and cladocerans. There are now numerous insect larvae in the sediment and some small fish in both lakes. The biological recovery, which followed substantial reductions in acidity and in soluble nickel and copper concentrations in the waters, is a slower process than chemical recovery and is initially characterized by the dominance of a few species.

Influence of organic and inorganic fertilization on the growth and nutrition of rice and fish in a dual culture system

SUMMARYField experiments were conducted for three consecutive years during 1988–90 at a research farm near the Indian Institute of Technology, Kharagpur, West Bengal, India to study the influence of organic and inorganic fertilizers on the performance of rice and fish in a dual culture system. Under waterlogged conditions the grain yield and dry matter of the rice variety CR1018 was increased both when inorganic N fertilizer (50 kg N/ha) was supplied or when a combination of organic (lOt FYM/ha) and inorganic N fertilizer (25 kg N/ha) were applied as compared with an organic fertilizer alone (20 t FYM/ha). The recovery of N as well as grain yield response per kg of N applied was also greater when inorganic N was applied. On the other hand, the growth of the fish species Java punti (Puntius javanicus) when grown alone (monoculture) and Catla (Catla catla), Mrigal (Cirrhinus mrigala) and Java punti (Puntius javanicus) grown together (polyculture) in the rice field was found to be superior when organic fertilizer was applied either alone or in combination with an inorganic fertilizer. The total number of phytoplankton species as food for the fish under organic manuring was more than under inorganic fertilization. In low-lying waterlogged situations (15–45 cm water depth), the total productivity could be increased by supplying the appropriate nutrition to both rice and fish in such dual culture systems.

Bottom-up effects of bream (Abramis brama L.) in Lake Balaton

Enclosures (17 m3) were used in the mesotrophic area of Lake Balaton to determine the impact of benthivorous bream (Abramis brama L.) on the lower trophic levels during summers of 1984–86. In enclosures with a fish biomass similar to the biomass in the eutrophic area of the lake, the number of phytoplankton species was highest. In enclosures with a low fish biomass the phytoplankton was dominated by the greens. A high biomass of bream in the mesotrophic basin caused bacterial production corresponding to that of the eutrophic part of the lake. Crustaceans were dominated by copepods and were unable to control phytoplankton peaks. Bottom-up effects of bream were more obvious than top-down effects and seem to be more important in the possible control of water quality.

Phytoplankton responses to reduction and elimination of submerged vegetation by herbicides and grass carp in four Florida lakes

Four central Florida lakes were monitored for 3 years to determine the effects of macrophyte reduction and elimination by grass carp and herbicide on phytoplankton populations. Clear Lake, in which grass carp were stocked after a year of baseline studies, had all macrophytes eliminated within 14 months. The density of phytoplankton increased significantly from an initial 24-month mean of 165 000 cells 1 −1 to a mean level of 787 900 cells 1 −1 in the third year. In Little Lake Fairview, stocked with grass carp in both the first and third years of study, vegetation was not eliminated until the 34th month. Phytoplankton density increased significantly from a 24-month mean of 64 200 cells 1 −1 to a mean of 370 200 cells 1 −1 in the third year. Lake Orienta, stocked with grass carp in the first year, had all vegetation eliminated within 6 months. Phytoplankton abundance did not change significantly over the course of the study (mean: 2 700 000 cells 1 −1). Lake Mann was treated with herbicide alone after an initial year of baseline data collection. Submerged vegetation was reduced in the second year but increased to near initial biomass levels in Year 3, with Nitella sp. replacing Hydrilla verticillata (L.f.) Royle as the dominant macrophyte. No significant yearly changes were noted in density of phytoplankton in this lake. Lake Orienta was the only lake in which the number of phytoplankton species collected differed significantly between years. Cyanophytes (notably species of Anacystis, Microcystis and Anabaena) and the diatom, Fragilaria sp., predominated in all lakes as macrophytes were removed. Most changes observed were in the direction of apparent increased trophic state. Major shifts in the phytoplankton assemblage (e.g., Shannon diversity indices and abundance) coincided with periods of maximal fluctuation in vegetation. Reversals of these tendencies were observed during prolonged stable periods of both high and low macrophute biomass.

Liming of Acidified Swedish Lakes and Streams and its Consequences for Aquatic Ecosystems

Abstract Acidification of poorly buffered lakes, with negative effects on fish populations as well as the functioning of whole aquatic ecosystems, prompted an extensive program for neutralization of surface waters in Sweden. The biological response to lake liming has been mainly positive, especially in lakes with water retention times of more than 1–2 years, and in lakes where the deleterious effects of acidification have been moderate. Liming promotes decompositional processes. Whether it results in a temporary or permanent increase in nutrient recycling, is not yet known. The number of phytoplankton species generally increases in limed lakes. Zooplankton species which are sensitive to acidification reappear often spontaneously in limed lakes within a few years. The benthic fauna, established during the acid period, changes over several years following liming. New species invade during the neutral conditions and populations of acid sensitive species, previously present at very low levels, expand. The bio...

Ecology of Swanpool, Falmouth: V. Phytoplankton and nutrients

Nutrient levels, plant pigments, oxygen balance and phytoplankton populations have been studied over a period of 2 years in a brackish-water lagoon. In general the lagoon was found to be supplied with abundant nutrients for plant growth by its freshwater inflow stream. Being shallow, it was therefore frequently eutrophic in summer. The number of phytoplankton species found in the pool was low, but several species showed marked continuity over the study period. Phytoplankton diversity was low, as often found in eutrophic lakes, and on occasions extremely low owing to the dominance of Gyrodinium resplendens. This species formed dense blooms which showed uneven horizontal and vertical distributions. In early summer, G. resplendens accumulated in strongly stratified layers of water about 1·5 m below the surface and caused maxima of oxygen and oxygen production at this level. Over the period of study some marked changes of species composition occurred, but these did not conform to any clear seasonal pattern such as that typical of many temperate freshwater lakes.

兵庫県神崎郡の池沼に産する植物プランクトン

Species composition of phytoplankton was studied in two groups of irrigation ponds close to Himeji City, Hyogo Prefecture. Sixty-three genera and 112 species were recorded from 12 ponds. The number of species was greatest in August with the highest water temperature and the smallest in cold January in both groups of ponds. A good correlation was found between the occurrence of rooted aquatic plants and the number of phytoplankton species. Ponds with a luxuriant growth of macrophytes generally had the large number of phytoplankton species. In Sara-ike, 43 species of Desmids were recorded.

鶴岡市公園3池(山形県)における植物プランクトンの季節的消長と黄金色藻の優位性

Seasonal changes of phytoplankton were studied with special reference to the Chrysophyceae in three ponds at Tsuruoka Park, Tsuruoka, Yamagata Prefecture from September in 1961 to September in 1962. 190 species, 15 varieties, and 2 forms of phytoplankton and 63 species and 9 varieties of zooplankton were recorded throughout the study period. 78 taxa of the Chlorococcales, 38 of the Chrysophyceae, and 37 of the Euglenophyceae formed 37.7%, 18.4%, and 17.9% of total number of phytoplankton species, respectively. The highest density of total phytoplankter cells in each pond was found in August in Pond No. 1 (43, 000 cells/ml) and Pond No. 2 (90, 000 cells/ml), and in May in Pond No. 3 (19, 000 cells/ml). The lowest desity was recorded in February in Pond No. 2, and in March in Ponds Nos. 1 and 3 (300-400 cells/ml). The Chlorococcales occured abundantly throughout the years studied. The Cyanophyceae dominanted in summer, the Chrysophyceae in winter. A large number of the Volvocales, the Bacillariophyceae, and the Euglenophyceae were found at a few samplings. The highest densities of phytoplankton cells, especially of the Chrysophyceae were found in winter when the temperature and pH values of pond waters were the lowest throughout the year. 3, 000 cells/ml in Pond No. 3 on February 6, 1962 was the highest value among three ponds, and occupied 78% of total phytoplankters in the pond.

Some Effects of Artificial Fertilization on Enclosed Plankton Populations in Marion Lake, British Columbia

After single applications of nutrients to enclosures in Marion Lake in each of three seasons (fall, summer, and spring), primary productivity always increased within a 2-week period whether nitrate, phosphate, or a combination of the two was used. The species that responded to the three nutrients generally differed both within and between seasons. In all seasons, there was a decrease in total plankton diversity (based on productivity) accompanied by an increase in relative productivity of a few phytoplankton species. During fall, phosphate (P) was most stimulatory, raising primary productivity 6 mg C/m3 per hr above that of the unenriched control. During spring, N + P was most stimulatory (23 mg C/m3 per hr) and nitrate (N) next (11 mg C/m3 per hr). In summer, N + P was again most stimulatory (44 mg C/m3 per hr), primary production in the untreated lake rarely exceeding 4 mg C/m3 per hr. Of the species that increased in density, 78% were not detectable (&lt; 1 cell/ml) at the time of fertilization. A rapid increase in density of rare species culminated in an algal bloom 2–3 weeks after fertilization.After the first phase of succession following fertilization, there was an increase in plankton diversity. At 1.5 months after fertilization, the diversity and the number of species detected were as high as or higher than before fertilization. In addition, the number of phytoplankton species per liter did not decrease significantly after enrichment though diversity decreased sharply due to the increase in abundance of a few species.