Temporary members include sea stars, crustaceans, marine worms, sea urchins, most fish, etc. All the species of plankton are adapted to certain structural adaptations , which enable them to float freely in the water. These adaptations are oil droplets, lateral spines, sheaths made of gel kind of substance, floats filled with gases, flat bodies. In this article, we will be discussing the difference between both kinds of plankton.
Zooplankton are the small aquatic animals. Mode of nutrition Phytoplankton prepare their own food by the process of photosynthesis autotrophs. Zooplanktons depend on phytoplanktons for their food and other matter found in sea heterotrophs. Habitat As they depend on sunlight for making their food, they primarily use to live on the surface of the water.
Zooplankton lives in the darker and colder area of the water body. Liberation of oxygen Being in the category of plants, Phytoplankton releases oxygen in the atmosphere. Zooplankton does not have such function. Movement Phytoplanktons are not the active swimmers and cannot move. Zooplankton can swim actively or passively. Ecological Importance 1. Phytoplankton serve as the basic food source for many marine animals. They also play a vital role in checking the stability in marine water, as they serve as an indicator of health of water.
Zooplankton also helps in checking the toxicity level in marine water. If there are sudden changes in water like increase in level of pollution, acidity, changes in temperature, these plankton reveal the early warning of the changes in the environment.
Examples Algae and Diatoms. Crustaceans and Small fishes, etc. One of the most common examples of the planktonic genus is Synechococcus and can reach the densities of 10 4 5 cells per milliliter. Changes in temperature or acidity or an increase in nutrients from farm runoff and pollution can all have dramatic effects on plankton.
Often, changes in plankton can reveal early warning signs of a problem in the environment. One sign of imbalance is termed a red tide. Red tides, also known as harmful algae blooms, are an overgrowth of algae, a type of phytoplankton, that can cover the surface of the water. In severe cases, the massive overgrowth of the algae can release sufficient toxins to cause a die-off of fish and marine animals in the area, creating what is known as a dead zone in the water.
Phytoplankton, which release oxygen through photosynthesis, are responsible for producing half of the world's oxygen. As well as forming the basis of marine food chains, these tiny organisms safeguard the Earth's atmosphere.
Niki Fears has been a writer and editor for more than four years and has written for a number of major sites. She specializes in natural health, nutrition, herbalism, environment, religion and spirituality, traditional medicine, culture, folklore and myth, and alternative news.
What Lives in the Photic Zone? What Are the Different Types of Phytoplankton? What Plants Live in the Oceanic Zone? 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.
Most clearly this impact was visible in winter, and less in summer. A positive influence on Rotifera was exerted by the nanoplanktonic Bacillariophyceae, but less by the microplanktonic Conjugatophyceae, Chrysophyceae and Chlorophyceae.
This influence was visible in all seasons, however, less frequently in summer, when it was often negative Fig. Triplot diagram for RDA including phytoplankton groups explanatory variables , zooplankton biomass dependent variables and samples.
Only eight groups of phytoplankton more statistically significant were shown. Acronyms: see Fig. One of the most important associations affecting phytoplankton abundance and biomass in lakes is zooplankton Kawecka and Eloranta, Negative relationship between these two groups is expected, which is the result of predation by zooplankton on phytoplankton. A positive relationship can indicate that phytoplankton growth can be stimulated by zooplankton.
Such relationships were obtained by simple and multiple regression analyses and partially by canonical correlation analyses and RDA. Taking into account 14 phytoplankton groups, it is possible to explain Because most phytoplankton and zooplankton variables are temperature dependent, a clearer result is probably shown by RDA analysis, in which water temperature was used as a covariable.
This analysis confirms the positive influence of zooplankton variables on Cryptophyceae mainly grazing rate and Conjugatophyceae Copepoda biomass.
The Cryptophyceae due to their flagella are possible to escape the grazing pressure of filtrators, whereas Conjugatophyceae are probably too small to be good prey for predatory copepods. This positive influence of grazing rate on species belonging to Cryptophyceae was proved by simple regression analysis and was probably connected with nutrient release by zooplankton, which stimulate algal growth Kawecka and Eloranta, This influence was also proved by calculated results of nutrient excretion by zooplankton Kowalczewska-Madura et al.
RDA did not confirm the positive relationship between zooplankton grazing and Cyanobacteria, which was probably the effect of autocorrelation. The negative effect shown in summer Fig. This is consistent with the laboratory experiments of Dawidowicz et al. Dawidowicz et al. The negative influence of Rotifera on nanoplanktonic algae resulting from RDA is in agreement with statement of Karabin Karabin, and Telesh Telesh, that these algae can be easily digested by rotifers.
Tadonleke et al. Trophic relationship may also explain the negative influence of Copepoda on microplanktonic algae, especially Dinophyceae, using RDA analysis.
Copepoda as reported by Sommer et al. Sommer et al. The canonical correlation analyses suggest that phytoplankton, especially when divided into 14 groups, can explain as many as This may be probably the effect of autocorrelation, because RDA did not confirm such intensive influence.
In both analyses, however, the positive effect of Cryptophyceae and microplanktonic Cyanobacteria on Cladocera was demonstrated. It is difficult to explain these relationships, because Cryptophyceae are not easy available for Cladocera. Cyanobacteria may represent a food of good quality in some cold months, but during summer many species are potentially toxic.
This may explain why RDA displayed the weak negative effect of microplanktonic Cyanobacteria on cladoceran biomass in summer. Such influence of Cyanobacteria was earlier reported, e. Reinikainen et al. The reason that there is a negative influence of nanoplanktonic Chrysophyceae and Euglenophyceae on Cladocera is not evident since they are considered a good food source for crustaceans Kawecka and Eloranta, This is possibly the effect of autocorrelation with other, unknown variables.
The domination of small species in the zooplankton community can be associated with fish predation pressure and by the negative influence of Cyanobacteria. Cyanobacteria clearly prevailed in the phytoplankton during the summer of the first 2 years of this study. When their numbers exceed a threshold value, they could exert a negative influence on the feeding, development and abundance of large cladocerans.
Also, cyanobacterial filaments make their foraging difficult they block the closing of the carapace , so these algae can influence the decline of the cladoceran community Dawidowicz, Larger-sized cladocerans mainly Daphnia spp.
According to Meijer Meijer, , in some conditions, they can contribute to the low level of phytoplankton biomass despite a high trophic state of the water. In August , cladoceran numbers decreased to 18 ind. This unfavourable influence of cyanobacterial blooms on cladoceran communities especially on Daphnia longispina has been observed in a eutrophic lake in Portugal Abrantes et al. In , cladoceran abundance did not decline, resulting in the calculated grazing rate that reached an unusually high value of Cyanobacterial abundance and biomass were then lower than in preceding years, and probably because cladocerans controlled their numbers.
This relationship is associated with the active breaking of single cyanobacterial filaments by the zooplankton, which can then easily feed upon the Cyanobacteria Gulati, However, it is likely that other variables physio-chemical, hydrological or biological may have influenced both the concentrations of the Cyanobacteria and cladocerans with the grazing rate the response to a lack of Cyanobacteria in the ecosystem.
The high grazing rates in the summer of also coincided with the greatest phytoplankton biomass at that time. Cyanobacteria dominance was replaced by dinoflagellates, with C. The large size of this species prevented its consumption by filter-feeding zooplankton, so the calculated grazing rate is potential rather than real. This was probably caused by incomplete filtration, and the high density of cladocerans, which negatively affected the feeding rate Helgen, Similar water blooms caused by large dinoflagellates including C.
Tomec et al. Grigorszky et al. Ceratium hirundinella is able to reach high numbers and biomass associated with its diel migrations in the vertical profile. As reported by Frempong Frempong, , it can migrate for distances of up to 5 m per day.
Whittington et al. This allows active photosynthesis in the surface layer of water at optimal light intensity, followed by absorption of nutrients near the bottom during other periods. Ceratium hirundinella also provides a suitable food source for advanced copepodite instars and adult cyclopoid copepods Santer, ; Sommer et al.
For instance, the high value for May However, this is not consistent with the relatively high abundance and biomass of phytoplankton recorded then. In conclusion, the distinct influence of zooplankton grazing and predation on phytoplankton abundance and biomass was not apparent in this highly eutrophic lake, in comparison to results obtained in enclosure experiments by other authors Sommer et al.
As we expected zooplankton suppress nanoplanktonic species, but not from all taxonomic groups. RDA proved only weak influence on nanoplanktonic Euglenophyceae and Chlorophyceae exerted by filtering crustaceans and on Cyanobacteria and Chysophyceae by rotifers. Simple regression proved that only some sensitive species were significantly suppressed by zooplankton. Owing to RDA there was indicated an unexpected distinct negative influence suggested grazing of filtrators exerted on microplanktonic Cyanobacteria during summer.
Positive influence of zooplankton grazing on Cryptophyceae both micro- and nanoplanktonic detected by RDA was a confirmation of results of simple regression between grazing rate and species belonging to Cryptophyceae. It indicated a stimulation of growth of species resistant to selective grazing or predation by zooplankton. We also thank the anonymous reviewer for many comments that helped improve the original manuscript.
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