Phytoplankton, Physicochemical characteristics, Trophic status and Saprobiological characteristics o

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Phytoplankton, Physico-chemical characteristics,
Trophic status and Saprobiological
characteristics of Bovan reservoir

• SNEANA CAÐO, ALEKSANDAR MILETIC ALEKSANDRA
  ÐURKOVIC
• Republic Hydrometeorologic Service of Serbia,
  Belgrade, Serbia and Montenegro

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Introduction

• The Bovan reservoir is situated in south-east of
  Serbia, near the town of Aleksinac
• It is made on the River Moravica, the right
  tributary of River Juna Morava, in 1978.
• At the beginning of forming and building, the
  errors have been made
• The reservoir is not properly located, nor the
  field for it has been properly prepared

• The waters of River Moravica and River Joanicka
  bring the sewage of Sokobanja town, ''Soko''
  mine, and the effluents of surrounding dwellings
  into Bovan reservoir
• Non-adequate preparation of field for the
  building of reservoir, insufficient protection of
  catchment area and huge income of nutrients,
  particularly in summer period during the
  touristic season, ended in euthrophication of
  Bovan reservoir.
• One of the most obvious consequences of
  euthrophication is water "blossoming'' as the
  result of destruction of self-regulation process
  in ecosystem

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The Bovan Reservoir
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The results of physico-chemical analysis of Bovan
reservoir in July 2003.
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The results of qualitative phytoplankton analysis

• 98 taxa have been determined from seven divisions
  of algae
• Cyanophyta 9 taxa
• Chrysophyta 2 taxa
• Bacillariophyta 30 taxa
• Xanthophyta 2 taxa
• Pyrrhophyta 3 taxa
• Euglenophyta 4 taxa
• Chlorophyta 48 taxa

• Dominant species Aphanizomenon flos-aquae (L.)
  Ralfs from the group of Cyanophyta
• Subdominant species Ceratium hirundinella
  (O.F.M.) Bergh from the group of Pyrrophyta

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The ratio between the concentrations of total
phosphorous and sillicium-dioxide in Bovan
reservoir

• The increase in ratio of Ptot against the
  soluble sillica in reservoir water, which can be
  caused by antrophogenic influence, will end in
  the change of phytoplankton community contents.
  The domination of sillicate algae will be
  replaced by the domination of bluegreen algae or
  flaghelates
• The examination results point out on high ratio
  between Ptot against soluble sillica which has
  beside the domination of bluegreen algae, also
  conditioned the presence of smaller centric forms
  among sillicate algae.

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The results on density and biomass of
phytoplankton and concentration of chlorophyll-a
of Bovan reservoir in July 2003.
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The density and biomass of phytoplankton and
chlorophyll-a ratio of Bovan reservoir in July
2003.

• Comparing the values of phytoplankton density,
  its biomass as well as the degree of primary
  production, given by the concentration of
  chlorophyll-a it can be concluded that their
  highest values are noted in surface water at the
  entrance of reservoir, and the lowest values at
  the dam locality at the highest depth.
• It can be also concluded that the variations of
  density and biomass values follow the variations
  of concentration of chlorophyll-a values

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The percential presence of certain algal groups
and species in phytoplankton in comparison to the
density and biomass
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The values of Saprobic indices on sampling
locality of Bovan reservoir in July 2003

• The results of saprobiological analysis show that
  in reservoir water the dominant organisms were
  those of ß-mesosaprobic and oligosaprobic zone.
  The values of saprobic indices varied from 1.63,
  in the deepest water at the dam locality and in
  the central part of the reservoir, respectively,
  up to 1.79 in the middle water at the entrance of
  reservoir

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Classification of the trophic status of Bovan
reservoir

• In the period of examination according to OECD
  classification of trophic status of the lakes and
  reservoirs, Bovan reservoir can be defined as
  euthrophic.
• At the entrance of the reservoir the average
  values of concentrations of total phosphorous,
  chlorophyll-a and transparency are characteristic
  for hypereuthrophic lakes.

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Conclusion

• The increased organic production ended in
  simplification of ecosystem and the disturbance
  in its function.
• The species diversity has been decreased and
  water quality is worsened.
• By the decomposition of algal biomass the
  decaying processes are increased with the
  increased consumption of oxygen up to its deficit
  in the lower water.
• The organic compounds are accummulated in water
  as the result of algal decomposition.
• Phitodethritus precipitates on the bottom of
  reservoir.
• From the sediment compilations, which are rich in
  organic and mineral compounds, in the conditions
  of oxygen deficit, in the period of thermic
  stratification, the resources of nutrients are
  recharged, first of all orthophosphates.
• Failures made during the forming of reservoir,
  morphometric characteristics, washing off the
  agricultural fields from the very neighbourhood
  of the reservoir and the high income of nutrients
  and other pollutants by River Moravica ended in
  increased euthrophication and ecosystem
  degradation.

• In surface water, the water blossoming was
  noted, which is the consequence of
  euthrophication
• high development of bluegreen algae is the
  consequence of
• the high water temperature
• lower water level
• suitable meteorological conditions
• very high nutrients concentrations
• morphometry of the reservoirs.