One of the most common examples of the planktonic genus is Synechococcus and can reach the densities of 10 4 5 cells per milliliter. In most marine and freshwater environments, Phytoplankton photosynthetic prokaryotes and eukaryotic organisms forms the basis of primary production. The dissolved and particulate organic matter is released by the phytoplankton and is further used by heterotrophic bacteria. A part of this material is consumed by the predators, which further releases the material and is used eventually used by phytoplankton.
Iron and nitrogen can limit these activities in the different marine environment. The overgrowth of algae, also known as algae blooms , is the type of phytoplankton indicating the high level of presence of toxins. It is also known as Red Tides. It results in the die-off of marine animals and fish in that particular water body and thus creating the dead zone. The two main classes are dinoflagellates and diatoms of phytoplankton.
They also play a major role in global carbon cycle. Zooplankton refers to the small animals, that swims in the water bodies.
Zooplankton is classified by size by their developmental stage and size like picoplankton, nanoplankton, microplankton, mesoplankton, macroplankton, mega plankton. They range from less than 2 micrometers to millimeters almost 8 inches. On the basis of the sizes, the zooplanktons are divided into two groups, which are meroplankton and holoplankton.
Meroplankton includes crustaceans, mollusks, echinodermata and some small fishes, these are the temporary members among plankton. They show a very different feature called as vertical migration in which at the night time zooplankton moves towards the surface of the water and at the day time they move down to the deep water.
This process protects the zooplankton from being eaten by the predators especially diurnal and also support the phytoplankton to produce their food in the presence of sunlight.
Many zooplankton moves deeper into the water during the day and gets back into the night. This migration is based on the season, size, age, and sex. Zooplankton is also affected by calcium, pH, heavy metals, calcium, and aluminum. Zooplankton is considered as wandering animals. Blooms in the ocean may cover hundreds of square kilometers and are easily visible in satellite images. A bloom may last several weeks, but the life span of any individual phytoplankton is rarely more than a few days.
Phytoplankton are the foundation of the aquatic food web, the primary producers , feeding everything from microscopic, animal-like zooplankton to multi-ton whales. Small fish and invertebrates also graze on the plant-like organisms, and then those smaller animals are eaten by bigger ones. Phytoplankton can also be the harbingers of death or disease. These toxic blooms can kill marine life and people who eat contaminated seafood. Dead fish washed onto a beach at Padre Island, Texas, in October , following a red tide harmful algal bloom.
Phytoplankton cause mass mortality in other ways. In the aftermath of a massive bloom, dead phytoplankton sink to the ocean or lake floor. The bacteria that decompose the phytoplankton deplete the oxygen in the water, suffocating animal life; the result is a dead zone. Through photosynthesis, phytoplankton consume carbon dioxide on a scale equivalent to forests and other land plants.
Some of this carbon is carried to the deep ocean when phytoplankton die, and some is transferred to different layers of the ocean as phytoplankton are eaten by other creatures, which themselves reproduce, generate waste, and die. Phytoplankton are responsible for most of the transfer of carbon dioxide from the atmosphere to the ocean. Carbon dioxide is consumed during photosynthesis, and the carbon is incorporated in the phytoplankton, just as carbon is stored in the wood and leaves of a tree.
Most of the carbon is returned to near-surface waters when phytoplankton are eaten or decompose, but some falls into the ocean depths. Even small changes in the growth of phytoplankton may affect atmospheric carbon dioxide concentrations, which would feed back to global surface temperatures. Phytoplankton form the base of the aquatic food web.
Phytoplankton samples can be taken directly from the water at permanent observation stations or from ships. Sampling devices include hoses and flasks to collect water samples, and sometimes, plankton are collected on filters dragged through the water behind a ship. Marine biologists use plankton nets to sample phytoplankton directly from the ocean. Samples may be sealed and put on ice and transported for laboratory analysis, where researchers may be able to identify the phytoplankton collected down to the genus or even species level through microscopic investigation or genetic analysis.
Although samples taken from the ocean are necessary for some studies, satellites are pivotal for global-scale studies of phytoplankton and their role in climate change. Individual phytoplankton are tiny, but when they bloom by the billions, the high concentrations of chlorophyll and other light-catching pigments change the way the surface reflects light.
In natural-color satellite images top , phytoplankton appear as colorful swirls. Scientists use these observations to estimate chlorophyll concentration bottom in the water. These images show a bloom near Kamchatka on June 2, The water may turn greenish, reddish, or brownish. The chalky scales that cover coccolithophores color the water milky white or bright blue. Scientists use these changes in ocean color to estimate chlorophyll concentration and the biomass of phytoplankton in the ocean.
Phytoplankton thrive along coastlines and continental shelves, along the equator in the Pacific and Atlantic Oceans, and in high-latitude areas. Winds play a strong role in the distribution of phytoplankton because they drive currents that cause deep water, loaded with nutrients, to be pulled up to the surface. These upwelling zones, including one along the equator maintained by the convergence of the easterly trade winds, and others along the western coasts of several continents, are among the most productive ocean ecosystems.
By contrast, phytoplankton are scarce in remote ocean gyres due to nutrient limitations. Phytoplankton are most abundant yellow, high chlorophyll in high latitudes and in upwelling zones along the equator and near coastlines. They are scarce in remote oceans dark blue , where nutrient levels are low. This map shows the average chlorophyll concentration in the global oceans from July —May View animation: small 5 MB large 18 MB.
Like plants on land, phytoplankton growth varies seasonally. In high latitudes, blooms peak in the spring and summer, when sunlight increases and the relentless mixing of the water by winter storms subsides. Recent research suggests the vigorous winter mixing sets the stage for explosive spring growth by bringing nutrients up from deeper waters into the sunlit layers at the surface and separating phytoplankton from their zooplankton predators.
In the subtropical oceans, by contrast, phytoplankton populations drop off in summer. As surface waters warm up through the summer, they become very buoyant. With warm, buoyant water on top and cold, dense water below, the water column doesn't mix easily. Phytoplankton use up the nutrients available, and growth falls off until winter storms kick-start mixing. In summer, the lake is characterized by oxygen depletion in the deeper layers of water and by high concentrations of total phosphorus and total nitrogen, reaching up to 1.
Its present trophic state has been classified as advanced eutrophic, or even hypertrophic Kowalczewska-Madura, The sampling station was located in the central, deepest point of north-eastern part of the lake. Water samples for phytoplankton analysis were taken just below the surface. Samples for analyses of chlorophyll a and zooplankton were collected using a 5-L Limnos water sampler every 1 m in a vertical profile.
Chlorophyll a was assessed with the Lorenzen method after extraction in acetone and corrected for pheopigments a Wetzel and Likens, Number of specimens in 1 mL was counted, assuming as 1 specimen was the cell, coenobium or filament, in dependence on the manner of occurrence. The biovolume of each species was estimated by applying closest geometric formulae following Hindak Hindak, and Wetzel and Likens Wetzel and Likens, Zooplankton biomass was calculated following Bottrell et al.
Bottrell et al. For the calculation of phyto- and zooplankton biomass, ca. Other species were measured occasionally or mean literature data were used. As the differences among zooplankton data in vertical profile were not statistically significant, mean values were calculated and generally taken into account.
Total redundancy indexes, which were calculated in these analyses, were used to estimate how much of the actual variability in one set of variables was explained by the other. All analysed data were converted to normal distribution.
They were also examined to detect possible outliers. As the data of phytoplankton and zooplankton were temperature dependent, they create time-dependent series. Higher values were recorded in spring and summer, and lower in winter. Differences in abundance were also observed between years. In terms of number of specimens, Cyanobacteria prevailed, accounting on average for The number of Cyanobacteria in summer reached ca.
The most numerous were Pseudanabaena limnetica Lemm. Apart from Cyanobacteria, Chlorophyceae, Bacillariophyceae and Cryptophyceae reached relatively high numbers Fig. Calculated biomass ranged from 5. Cryptophytes accounted for the highest mean contribution The dominant species in terms of biomass were Cryptomonas reflexa Skuja and Cryptomonas curvata Ehr.
Their biomass reached up to Also diatoms and green algae were important contributors to total biomass. A marked increase in phytoplankton biomass was recorded in August This was due mainly to dinoflagellates, especially the dominant Ceratium hirundinella f. Greater values of nanoplankton were observed twice a year—in early spring March and late summer August—September Fig. Chlorophyll a concentration indicated seasonal fluctuations Figs 3 and 6 similar to those of phytoplankton biomass.
Its value decreased with the increasing depth of the vertical profile of the lake. The highest values were usually recorded at the surface or at the depth of 1 m.
The maximum value was The zooplankton community was composed of 96 taxa, including 67 rotifers, 17 cladocerans and 12 copepods. Juvenile stages of copepods nauplii, copepodids were considered jointly. Zooplankton abundance ranged from 7 February to 19 ind.
In terms of abundance, zooplankton was dominated by rotifers, which reached ca. The dominant rotifer taxa were: Keratella cochlearis Gosse, K. Cladoceran numbers varied from 1 February to ind. Among the copepods, juvenile stages were the most numerous, accounting on average for Zooplankton biomass ranged from 0. Copepods accounted on average for Among cladocerans, the most important biomass contributors were Daphnia cucullata and Leptodora kindti Flacke.
The biomass of rotifers varied from 0. The maximum value, much higher than in any other month of the study, was recorded in May , when it was to A comparison of the annual summer means June—September shows that was characterized by the highest grazing rate, when the summer mean was In , the corresponding value was In the vertical profile, calculated grazing rates were highest at 2 m and the lowest near the bottom, i.
The maximum In colder periods, the highest grazing rates were recorded for Eudiaptomus gracilis , up to 5. In both models, the same zooplankton species were the most efficient filter feeders. The canonical correlation analysis comparing the zooplankton variables grazing rate, rotifers and copepods biomass—left set Table III versus two size groups of phytoplankton nano- and microplankton—right set Table III indicated a similar relationship. Canonical factor loadings suggested that grazing rate and rotifers were associated with a positive influence on the microphytoplanktonic biomass, whereas copepods, negative one Table III.
Canonical weights, however, indicated a negligible role of Rotifera in this process. Canonical weights explain unique contributions of the respective variables with a particular weighted sum or canonical variate, so they are more important than factor loadings, which only overall correlation of the respective variables with the canonical variate.
The influence of zooplankton variables on nanophytoplanktonic biomass was positive, but very weak. Grazing rate together with rotifer and copepod biomass explained about more twice the variance The positive influence of zooplankton on phytoplankton variables indicated above was not identical with the results of canonical analysis using 14 phytoplankton groups.
Canonical factor loadings testified that this positive influence on microplankton was exerted mainly on Cryptophyceae, less on Conjugatophyceae and Cyanobacteria. However, this influence was distinctly negative on nanoplanktonic Euglenophyceae and Chrysophyceae and also positive on nanoplanktonic Cryptophyceae, Cyanobacteria and Chlorophyceae Table IV.
Canonical weights of phytoplankton groups mentioned above were also the largest, showing their important contribution to the right canonical variable. The canonical factor loadings and weights of zooplankton variables left set and of biomass of two phytoplankton size groups right set as a result of canonical correlation analysis presented in Table II. Only statistically significant data of the first canonical root are given.
Acronyms see Table II. Example of canonical factor loadings and weights of particular variables as a result of canonical analysis of three zooplankton variables versus 14 phytoplankton groups, presented in Table II. The RDA analyses confirmed the distinct positive influence of grazing rate on large and small cryptophytes.
It was visible mainly in winter, but less in autumn and spring Fig. It was not indicated, however, for Cyanobacteria where there is a distinct negative influence, suggesting a possible grazing of filtrators on Cyanobacteria that occurred mainly in summer.
A lesser negative influence of grazing rate was indicated for the microplanktonic chlorophytes, diatoms and euglenophytes. A similar low negative influence was with the nanoplanktonic chlorophytes algae and euglenophytes during autumn and winter Fig. Rotifers exerted mainly a negative influence on nanoplanktonic Cyanobacteria and Chrysophyceae and partly on microplanktonic Dinophyceae and Cyanobacteria.
Similar, though weaker influence was exerted by Copepoda. This group exerted also positive, though rather weak effect on microplanktonic Conjugatophyceae, nanoplanktonic Bacillariophyceae and Euglenophyceae Fig. Temperature data were used as a covariable. The above analyses were generally confirmed by simple regression analyses between the grazing rate and particular phytoplankton species. These analyses identified the grazing sensitive species negative correlation and grazing resistant species positive correlation.
Small, taxonomically diverse flagellated species belong to the first group: Chrysococcus skujae Heyning , Ch. Larger cryptophytes and mostly coenobial green algae belong to the second group: C. Chodat , Selenastrum capricornutum Printz , Tetrastrum triangulare Chod. Reversal of the RDA analysis made possible the evaluation of phytoplankton influence on the zooplankton biomass.
Microplanktonic Cyanobacteria and Cryptophyceae positively influenced Cladocera, but not in summer months. Instead of this, weak negative influence was visible in summer Fig. Distinct negative influence on Cladocera partly on Copepoda was exerted by nanoplanktonic Chrysophyceae and Euglenophyceae.
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