Alexandru ioan cuza




Дата канвертавання17.04.2016
Памер51.51 Kb.
ALEXANDRU IOAN CUZA” UNIVERSITY, IAȘI

Faculty of BIOLOGY

ANIMAL BIOLOGY Department

BIODIVERSITY OF CLADOCERANS

(CRUSTACEA, CLADOCERA)

OF THE TINERETULUI LAKE, BUCHAREST

SUMMARY OF DOCTORAL DISSERTATION

Author: HURDUGAN (MARRIED IRIMIA) ORIANA

Doctoral advisor

Prof. dr. GHEORGHE MUSTAȚĂ

Iași

28 May 2013

The present paper aims to address anthropogenic urban lakes ecology through the detailed study of zooplankton biodiversity in Tineretului Lake from Bucharest, especially of cladocerans biodiversity, the primary consumer of unicellular algae but also the main food for many fish species of economic and environmental interest.

The study was structured and elaborated so as to highlight the following objectives proposed:


  • Realization of a study with monographic character of the city centre situated Tineretului Lake, ignored by the biologists until recently, with the exception of some ornithological observations. Thus the geographical, climatological, hydrological, physical and chemical characteristics were registered and it was made the first inventory of biocenosis, from phytoplankton and submerged macrophytes to zooplankton (especially cladocerans, copepods, aquatic insects) and fish, and also the inventory of lake’s herpetofauna and avifauna as well as of the protected species present.

  • Adaptation of different cladocerans sampling methods to the specific of plain lakes rich in submerged vegetation with a large variety of habitats (muddy, epiphytic, pelagic, macrophytic ecotops, concrete or flooded banks) and also the realization of the first zooplankton sampling efficiency study on various methods proposed by the established literature.

  • Determination of the qualitative structure of cladocerans populations and also the comparison of their biodiversity with the one observed in the similar periurban and intraurban reservoirs.

  • Analysis of some aspects of quantitative and qualitative dynamics for these populations (abundance, diversity, frequency, dominance, ecological significance index, similarity coefficient) and their relationship with physical, chemical and biotic parameters’ evolution in the Tineretului Lake over eight seasons complex monitoring.

  • Analysis of the effect of aquatic macrophytes presence on the physical and chemical parameters of the lake water and also on the zooplankton, especially on cladocerans.

  • Realization of a laboratory study on the homeostasis predisposition of the spring Potamogetonetum associated microbiocenosis through daily observations over 45 days.

  • Highlighting the cladocerans position and role within the analysed ecosystem, and also of certain issues regarding the use of cladocerans as ecological indicators for the status of anthropogenic aquatic ecosystems.

During the field research, was discovered the historical and complex link between Tineretului Lake and Văcărești Pond, ”the Downtown Delta” as it was named, proposed for improvement and protection inside the Nature 2000 network. Tineretului Lake is an important reservoir of algal, macrophytic, zooplankton and avian biodiversity for the Văcărești Pond, a constant communication being established between the birds populations from the two lakes, acting as vectors for zoochore plant and animal species.

This aquatic body is not fed by any of the rivers crossing Bucharest, Colentina or Dâmboviţa, therefore not subject to ecological monitoring by Environmental Protection Agency of Bucharest. Instead, it is fed by helocrene type springs strong enough to ensure a constant level, even during the summer drought of 2007 and with a thermoregulatory role.

The lake has a natural elongated form, with three islands, linked to the shore by bridges, fitting harmoniously into the sinuous shores, with various usage profiles: the south islands, bigger, remained covered with vegetation, while on the north island, the smallest, was established a platform linked to the shore by a covered wooden bridge, also used for public recreational purposes.

It contains a variety of habitats, such as concrete banks which are flooded during the summer, forming temporary pools, favourable to plankton development, assemblages of willow logs housing sedentary and migratory birds and providing rest platforms for pond turtles, an area with reed and poplar saplings in the NE part of the lake, near the terrace, and a similar area in the northern part of the Big Island, used as a nesting place by wild mallards. It is divided in two water bodies by a very shallow bank, situated under the bridge from the eastern part of the lake. These water bodies have different usages: leisure crafting with rowing boats and rod angling in the north-eastern sector. and rod fishing from the shore, on a limited range in the rest of the lake.

The lake is managed by the Lakes, Parks and Recreation Administration of Bucharest and the aquatic vegetation is periodically removed through manual and mechanic means and it was periodically populated with juveniles from fish species of economic interest until 2009.

F
ig. 1. Tineretului Lake with sectors marked: I – NE sector: 1 – „Terrace” – Coffee shop; 2 – „Bridge” – Concrete bridge that separates the two big sectors, NE and SV; II – central sector: 3 – „Logs 1” – assemblages of floating willow logs; 4 – concrete shore with cedars; 5 – Big Island; 6 – Fishery; 7 – Small Island; III – „Oala Mică” sector: 8 – „Logs 2” – assemblages of floating willow logs. Google maps 2011, adapted by Hurdugan-Irimia Oriana.


Table 1. The main dimensions of Tineretului Lake (measured on the map at scale 1:38).

No.

Measured dimension

Abbreviation

Length

[m]

1

Perimeter

P

2757.17

2

Total length

Lmax =LI +LII+III

1196.07

3

Sector I length :Terrace - Bridge

LI

318.43

4

Sectors II+III length: Bridge- Oala Mică

LII+III

877.63

5

Maximum width (sector I - Terrace)

lmax

186.40

6

Secondary width (sector II -Fishery – Big Island)

lII

135.92

7

Width at the Bridge

lPOD

34.95

8

Minimum width (in front of the Small Island)

lmin

23.30

9

Tertiary width (sector III - Oala Mică )

lIII

112.62

The colorimetric titration it was used for the physical and chemical description of the lake water. The first three sets of analysis of the physical-chemical factors were carried out in all ecological significant points: springs, discharge point, islands, open water areas and vegetated areas. The test results differences were below testing accuracy, the only relevant difference being a gradation of certain environmental factors between the north-western sector, location of the underground springs, and the NE area, heavily anthropic, where the water level is adjusted, virtually, the only exit point of the lake towards the Dâmboviţa cased collector. Therefore, all further physical and chemical determinations were performed at the lake’s origin and discharge points allowing the monitoring of water quality evolution before and after its passage through the mass of macrophytic vegetation.

The medium depth of the lake is 2.3 m, with a range of depths measured between 1.7 m at Oala Mică and Terrace to 2.8 m or even 3.2 m in some places in the Fishery area or log islands areas. The shallow depth of the lake is the reason for which the lake does not present significant vertical variations of the water temperature, the difference between the surface and the bottom layers being generally of only 2-3ºC during the cold season and 1-2ºC during summer. The average water temperature ranged from 8ºC in winter to 25ºC in the summer.

The analyzed parameters showed optimal values ​​for the period from March to April, in conjunction with macrophytic vegetation growth period, which reached its maximum height and density of development during late April. After the vegetation harvesting period of May 2008 the water quality deteriorated significantly, the phytoplankton was stimulated by light and high temperatures and mass bloomed. The water quality follows closely the evolution of aquatic macrophytes presence, especially of Potamogeton crispus.

48 species of cyanobacteria and proctista were identified in the phytoplankton samples and 46 species in the epiphytic samples. The phytoplankton was dominated by Ord. Chlorococcales with 12 species, followed by Ord. Naviculales with 9 species, then Fragilariales and Chorococcales with 4 species each. The periphyton was dominated by the orders Chroococales, Desmidiales and Chorococcales, each with 5 species. Regarding the submerged aquatic macrophytes, they are represented by only two species: Potamogeton crispus and Miriophyllum spicatum.

The invertebrates identified in Tineretului Lake are truly planktonic or nektonic species, mostly macrophytofilous but also benthic species whose life cycle has one or more aquatic stages, like Notonecta glauca, Corixa punctata, Plea minutissima, Gerris lacustris (the only epineuston representative identified in this acvatory), Culex pipiens and Chyronomus.The crustaceans are present in large numbers, the vast majority comprising the Tineretului Lake zooplankton, together with rotifers: Macrocyclops albidus, Acanthocyclops vernalis, A. robustus, Eucyclops serrulatus proximus, Cypria sp. The latter were very abundant, sometimes dominant in zooplankton samples.

The molluscs are represented by Viviparus acerosus rumaenicus and Stagnicola palustris.

The Tineretului Lake ichtyofaune comes, without exceptions, from the fish farms around Bucharest, being introduced for the purpose of sport fishing. The following species were identified: Esox lucius, Carassius auratus gibelio, Cyprinus carpio, Ctenopharyngodon idella, Hypophthalmichthys nobilis, Pelecus cultratus (protected by the Berne Convention), Scardinius erythrophthalmus, Perca fluviatilis, Silurus glanis (species in regression, protected by the Berne Convention).

The herpetofauna is represented by: Rana esculenta (protected by the Berne Convention), Rana lessonae, Bufo viridis, Trachemys scripta elegans (invasive species), Emys orbicularis (CITES appendix III, strictly protected in Romania).

The avifauna is represented by: Anas plathyrhynchos, Anas querquedula, Anas strepera, Anas clypeata, Anas crecca, Anas penelope, Bucephala clangula, Cygnus olor, Chlidonia hybridus, Larus argentatus, Larus ridibundus, Larus canus, Egretta garzetta, Nycticorax nycticorax, Phalacrocorax pygmaeus, Tachybaptus rufficolis, Fulica atra, Galinulla chloropus.

In total 37 species protected by the Berne Convention and CITES Convention have been identified in Tineretului Lake and its immediate vicinity.
5 fixed stations and 6 mobile stations were established for zooplankton sampling, based on the ecological diversity of the lake. Measurements were made in the points of origin and the mouth of the lake of the physical-chemical parameters (pH, nitrite, nitrate, ammonia, carbonates, dissolved oxygen and dissolved carbon dioxide, temperature, transparency). In the established stations fortnightly and monthly samples were taken for 8 seasons or 3 years (2007-2009). The biological material was preserved in 4% formaldehyde at the site and identified in the laboratory to subspecies level, in order to determine the dynamics of species in terms of abundance, frequency, dominance, ecological significance and similarity.

90 samples were collected and analyzed in which were identified 12774 cladocerans, at the level of subspecies, gender and approximate age. 15 taxa were identified, classified in 11 genera, 6 families and two orders, according to the latest taxonomic reshuffle of the supraorder.

The Tineretului Lake falls within lotic ecosystems category with a significant cladocerans biodiversity between the previously studied Romanian intra- or peri-urban ecosystems.

The identified species are: Sida crystallina O.F. Müller, 1776, Simocephalus exspinosus (Koch, 1841); Simocephalus vetulus (O.F. Muller, 1776); Bosmina longirostris O.F. Müller 1875; Illiocryptus agilis Kurz, 1878; Macrothrix laticornis Fischer, 1851; Alona costata Sars, 1862 emend. Van Damme, 2010, Alona quadrangularis O.F. Müller, 1776 emend. Van Damme, 2010; Alona affinis Leydig, 1860 emend. Van Damme, 2010; Coronatella rectangula comb. nov. Alona rectangula Sars, 1861 sensu Van Damme, 2010; Camptocercus rectirostris Schoedler, 1862; Leydigia acanthocercoides (Fischer, 1854); Chydorus sphaericus caelatus Smirnov 1996; Chydorus sphaericus O.F. Müller, 1785; Pleuroxus aduncus Jurine, 1820



Alona quadrangularis and Coronatella rectangula (syn. Alona rectangula) from the Alona complex sensu Van Damme, 2010 were described for the first time in Romania.

Chydorus sphaericus caelatus, Alona costata and Camptocercus uncinatus species are first cited for the Dacian Plain.

The most abundant species were Bosmina longirostris with 6521 specimens, Chydorus sphaericus with 5654 specimens, followed by Alona affinis with 292 specimens and, respectively, Pleuroxus aduncus with 161 specimens. Also, there were species represented in the samples sorted by just one individual: Camptocercus rectirostris and Macrothrix laticornis.

In Tineretului Lake, between 2007-2009, Chydorus sphaericus was the only constant species. The Alona affinis, Pleuroxus aduncus and Bosmina longirostris species were accessory and the other species were framed in accidental species category.

Two species were dominant: Bosmina longirostris and Chydorus sphaericus, one subdominant species: Alona affinis and one recedent species: Pleuroxus aduncus, the remaining species being subrecedent.

Two species were distinctive (W5): Chydorus sphaericus and Bosmina longirostris. Another two species were accessory (W2) Alona affinis and Pleuroxus aduncus. The other species were coincidental (W1).

Fig. 2. Seasonal evolution of the average monthly abundance of cladocerans identified in Tineretului Lake, Bucharest.


The ecology of the species identified in the lake confirms that the macrophytic vegetation plays an decisive role in maintaining the ecological balance of the urban lacustrine ecosystem of the Tineretului Lake.

Chydorus sphaericus, a characteristic species, was the most frequent and one of the dominant species over the study period, reaching densities between 5 and 135 individuals/m3.

Bosmina longirostris, the second characteristic species, much less frequent, recorded the highest values in terms of abundance, but over small areas, the plankton cloud phenomenon reported in the years 1960-1980 in lakes of the Romanian Plain and the Danube Delta not being recorded here. The two abundance peaks were formed by two cyclomorphotic forms, B. longirostris f. typica in the spring samples and B. longirostris f. similis in the autumn samples, and also by a all year form, B. longirostris f. cornuta.

On the contrary, a higher concentration of individuals of Alona affinis, Chydorus sphaericus, Pleuroxus aduncus (oxyphilous) and also the presence of some individuals from species Sida crystallina and Simocephalus vetulus indicated a good or very good lake water quality, with an oxygen content over 7 mg/l. This was the case for the periods when the macrophytic vegetation was abundant in the lake, meaning during a good part of 2008 summer, March and April of 2009 and the beginning of autumn of 2008 and 2009.

Cladocerans species diversity varies widely from one period to another and from one stationary to another, as well as their abundance, from 6524 individuals for Bosmina longirostris species to only one individual for Camptocercus rectirostris and Macrothrix laticornis species.

Ilyocryptus agilis specimens infected with Blastodinium spinulosum trophozoids as well as Alona affinis individuals infected with Caullerya mesnili in the egg pouch and on the gonads are recorded for the first time.

The highest similarity value, was identified for Alona affinis and Chydorus sphaericus species. The triad Chydorus sphaericus, Alona affinis and Pleuroxus aduncus forms a macrophytophilous guild frequently found in open water samples. They share the habitat with Bosmina longirostris but the abundance peaks in different physical and chemical and biotic conditions. Bosmina longirostris is typically pelagic, eutrophic and its abundance weighs more than its frequency in the similarity ratio.

The dynamics and competition between Chydorus sphaericus and Bosmina longirostris can be easily traced, their succession being a good ecological indicator of changes in water quality.

Simocephalus exspinosus and Alona quadrangularis form a predominantly epiphytic and tychoplanktonic guild, thus found in a variety of stations, including transect samples. The Jaccard estimator also registered statistically significant values for Simocephalus vetulus and Alona costata species, found mainly in the Big Island temporary ponds, on pelophilous and epiphytic substrate. Species Macrothrix laticornis and Ilyocryptus agilis are typically pelophilous, detritivorous species. Leydigia acanthocercoides, Macrothrix laticornis, Chydorus sphaericus caelatus, Camptocercus rectirostris are rare species, occasionally found in Tineretului Lake.

The tolerance for basic pH values was expanded for several species of cladocerans: Alona affinis (syn. Biapertura affinis), Camptocercus uncinatus, Ilyocryptus agilis, Pleuroxus aduncus, Simocephalus exspinosus.



Bosmina longirostris seems to prove thermophilic and eurithermic, its maximum abundance being correlated with the higher water temperatures during the year. The high water temperature negatively affected the overall abundance of cladocerans, being a limiting factor for Ch. sphaericus, Alona spp. and Pleuroxus aduncus.

Chydorus sphaericus was sensitive to water transparency, its abundance being directly linked with a good water transparency. Meanwhile Bosmina longirostris recorded abundance maximum during maximum water turbidity periods.

Carbonate ion concentration is directly correlated with the abundance of hard shell cladocerans species, such as Chydorus sphaericus and Pleuroxus aduncus. In contrast, the abundance of Bosmina longirostris is inversely correlated with the carbonate concentration, this species having a very soft and transparent shell.

Small tanks like temporary ponds, flooded areas, ditches, etc., are particularly important for biodiversity, confirming at micro level what has long been known at macro level, i.e. the Danube floodplain, a reservoir of biodiversity for the entire Holarctic region.

The succession of cladocerans communities throughout the year, particularly of the planktonic species, reflects the water quality evolution under the influence of increasing water temperature especially and lack of macrophytes, generated artificial. Such cases are repeating more often in the coming years due to the increase in average monthly temperature, especially in metropolitan areas (under enhanced greenhouse effect of buildings and urban infrastructure elements) already observed for the past 10 years in Bucharest.



Cladocerans can be used as ecological indicators of both state of the moment of urban aquatory quality as well as of their evolution in time. Through a regular monitoring, cladocerans associations may even allow the development of productive capacity forecast models for water bodies used in fish farming or aquaculture of any type.



База данных защищена авторским правом ©shkola.of.by 2016
звярнуцца да адміністрацыі

    Галоўная старонка