© Acta hydrotechnica 21/35 (2003), Ljubljana
ISSN 1581–0267
129
UDK/UDC: 504.4:556.53:574.5 Prejeto/Received: 18. 6. 2004
Izvirni znanstveni članek – Original scientific paper Sprejeto/Accepted: 14. 12. 2004
UPORABA PERIFITONA IN VE ČJIH VODNIH NEVRETEN ČARJEV PRI
DOLO ČANJU EKOLOŠKO SPREJEMLJIVEGA PRETOKA NA REKI
RIŽANI, SLOVENIJA
THE USE OF PERIPHYTON AND MACROZOOBENTOS IN
DETERMINATION OF ECOLOGICALLY ACCEPTABLE FLOW
FOR THE RIŽANA RIVER, SLOVENIA
Nataša SMOLAR - ŽVANUT, Ciril KRUŠNIK, Gorazd KOSI, Danijel VRHOVŠEK
Edini ve čji izvir v slovenski Istri je kraški izvir reke Rižane, ki predstavlja najpomembnejši vir
oskrbe z vodo za slovensko obalno obmo čje. V poletnih mesecih je naravni pretok dokaj nizek, saj
voda delno pronica v tla, nekaj pritokov reke Rižane pa se izsuši. Isto časno pa sta v tem letnem
času potreba po oskrbi s pitno vodo in namakanje najve čja. V obdobju od 1995 do 1996 je bil
izdelan seznam vseh porabnikov vode in popis onesnaževalcev. Izvedene so bile hidrološke analize
od izvira do ustja reke Rižane. Z analizami perifitonskih alg in ve čjih vodnih nevreten čarjev se je
ugotavljala kakovost vodnega ekosistema na razli čnih odsekih reke Rižane. Zaradi velikega
odvzema vode in onesnaženja je prišlo do sprememb v raznolikosti združb ve čjih vodnih
nevreten čarjev, perifitonskih alg in biomase perifitona (suhe teže brez pepela (AFDW), suhe teže
(DW), klorofila-a (chl-a)). Na podlagi saprobioloških analiz je bila reka uvrš čena v I.–II.
kakovostni razred. Ocena kakovosti, ki je temeljila na indeksu (ocenjevalnem sistemu) BMWP
(Biological Monitoring Working Party) in indeksu EBI (Extended Biotic Index), je pokazala na
poslabšanje kakovosti vodnega okolja v nižjih delih reke. Da bi ohranili ekološko ravnovesje, je bil
dolo čen ekološko sprejemljiv pretok za poletne mesece na osnovi ekološke metode.
Klju čne besede: perifiton, ve čji vodni nevreten čarji, ekološko sprejemljiv pretok, kakovost vode,
kakovost vodnega okolja
The only major spring in the Slovenian Istria is the karst spring of the Rižana River, which is the
most important source of water supply for the Slovenian coastal area. In summer months the
natural flow is very low, whereby part of water drains off into the underground and several
tributaries of the Rižana River dry up. At the same time, the need for water supply and irrigation
are at their highest. In the period from 1995 to 1996, the list of all water users and the inventory of
polluters were made. From source to mouth of the Rižana River, the hydrological analyses were
carried out. The river ecosystem was evaluated according to analyses of periphytic algae and
macroinvertebrates on different sections of the Rižana River. Because of large water abstraction
and pollution of the river, changes in diversity of macroinvertebrates, in diversity of periphytic
algae and in periphyton biomass (ash free dry weight (AFDW), dry weight (DW), chlorophyll a (chl
a)) were established. Based on saprobiological analyses, the river is classified as quality class I–II.
The evaluation of quality based on BMWP score system and EBI, indicated a deterioration of the
aquatic environment in lower parts of the river. In order to maintain the ecological balance, the
ecologically acceptable flow (EAF) was determined according to the ecological method for summer
months.
Key words: periphyton, macrozoobenthos, ecologically acceptable flow, water quality, quality of
aquatic environment

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
130
1. UVOD
Podobno kot drugje v Sredozemlju je na
obmo čju slovenske Istre malo vodnih virov.
Edini ve čji izvir je kraški izvir reke Rižane, ki
predstavlja najbolj pomemben vir oskrbe z
vodo za slovensko obalno obmo čje. Dolvodno
je opaziti pove čano gostoto prebivalstva z
vsemi spremljajo čimi, tudi negativnimi pojavi,
kot so poseljevanje, kmetijstvo, industrija,
trgovina, promet in odlagališ ča. Potrebe po
pitni vodi, vodi za kmetijstvo in industrijo
presegajo vodne kapacitete reke Rižane.
Za dolo čitev minimalnega sprejemljivega
pretoka obstaja nekaj metod (Petts &
Maddock, 1995): hidrološke metode
(Schälchli, 1991; Mader, 1992), metode za
oceno vodotokov (Büttiker, 1982; Bundi &
Eichenberger, 1989; Statzner & Müller, 1989;
Schälchli, 1991; DVWK, 1995; Bernardo &
Alves, 1999) in PHABSIM (Physical HABitat
SIMulation) (Institute of Hydrology &
Institute of Freshwater Ecology, 1993; Lamb,
1995; Maddock et al., 2001). Ob upoštevanju
hidroloških, hidravli čnih, morfoloških in
ekoloških kriterijev se v Sloveniji trenutno
uporabljata dve metodi: hidrološka in ekološka
metoda (Vrhovšek et al., 1994; Vrhovšek &
Smolar, 1997; Smolar et al., 1998; Smolar -
 Žvanut & Vrhovšek, 2002).
Zaradi velikega odvzema vode in skoraj
popolne odsotnosti vode poleti v spodnjih
delih reke Rižane je bila ocenjena vrednost
ekološko sprejemljivega pretoka (Qes) z
interdisciplinarnim pristopom (ekološka
metoda) z namenom, da se zagotovi
izboljšanje razmer za vodne organizme
(Smolar et al., 1997).
V članku se osredotočamo predvsem na
uporabo ve čjih vodnih nevreten čarjev in
perifitonskih alg pri dolo čanju ekološko
sprejemljivega pretoka za reko Rižano.
1. INTRODUCTION
Like throughout the Mediterranean, the area
of Slovenian Istria is very poor in water
sources. The only major spring is the karst
spring of the Rižana River, which is the most
important source of water supply for the
Slovenian coastal area. Downstream, the
increasing density of population with all
relevant, and also negative phenomena, such
as settlements, agriculture, industry, trade,
traffic and landfill-sites can be observed. The
demand for drinking water, as well as the
industrial and agricultural exploitation of the
Rižana River have exceeded the water capacity
of the river.
There are some methods available for the
estimation of minimum acceptable flows (Petts
& Maddock, 1995): hydrological methods
(Schälchli, 1991; Mader, 1992) river
assessment methods (Büttiker, 1982; Bundi &
Eichenberger, 1989; Statzner & Müller, 1989;
Schälchli, 1991; DVWK, 1995; Bernardo &
Alves, 1999); and PHABSIM (Physical
HABitat SIMulation) (Institute of Hydrology
& Institute of Freshwater Ecology, 1993;
Lamb, 1995; Maddock et al., 2001). Based on
the hydrological, hydraulic, morphological and
ecological criteria, the hydrological and
ecological method is currently being applied in
Slovenia (Vrhovšek et al., 1994; Vrhovšek &
Smolar, 1997; Smolar et al., 1998; Smolar -
 Žvanut & Vrhovšek, 2002).
Because of major water exploitation and an
almost complete absence of water in summer
in lower parts of the Rižana River, the relevant
ecologically acceptable flow (EAF) value was
evaluated by means of the interdisciplinary
approach (ecological method) in order to
achieve the improvement of conditions for
water organisms (Smolar et al., 1997).
This paper describes specifically the use of
macroinvertebrates and periphytic algae in
determining the EAF in the Rižana River.

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
131
2. MESTO RAZISKAV
Prispevno območje 14 km dolge reke
Rižane (slika 1) obsega 204,5 km
2
. Reka te če
po kraškem zaledju s pretežno flišnim
obmo čjem, z izlivom v Jadransko morje čez
braki čno mokriš če.
Za obmo čje je zna čilna blaga
submediteranska klima z blagimi zimami in
dokaj visokimi poletnimi temperaturami
predvsem od za četka maja do konca
septembra. Suše so v tem obdobju pogoste.
Srednja letna raven padavin je približno 1000
mm v obalnem obmo čju, v višjih legah reke
Rižane pa je letna koli čina padavin povpre čno
1150 mm. Letna porazdelitev padavin je
neenakomerna, kar pomeni, da je poleti veliko
neviht, ko voda hitro odteka in izpareva.
Reka Rižana je vir oskrbe s pitno vodo že
od leta 1935. Neposredno pod akumulacijo je
odvzem vode, namenjen za ribogojnico in za
namakanje. Dolvodno je še 15 vodnih zajetij,
poleti pa tudi nekaj nenadzorovanih odvzemov
vode za namakanje. Posledice so vidne
predvsem v poletnih mesecih, ko zaradi
poslabšanja vodnega okolja prihaja do poginov
rib. V tem obmo čju se je izvedlo tudi ve č
hidrotehni čnih posegov.
Za strugo vzdolž vodotoka so zna čilni
razli čni substrati; gorvodno so to ve čji kamni,
dolvodno pa se struktura re čnega dna
spreminja od proda do mulja. Reka Rižana ima
status športno ribolovne vode, mlinš čice ob
reki pa so na seznamu okoljsko zaš čitenih
obmo čij za trajnostno gojenje soške postrvi
Salmo marmoratus. V bližini reke pogosto
najdemo združbe Ostryo - Quercetum
pubescentis, Carici humulis - Centaureetum
rupestris in Bromo - Chrysopogonetum grylli.
Obvodna vegetacija je okrnjena zaradi
obdelane zemlje in bližine cest.
Na reki Rižani smo izbrali 4 vzor čna mesta:
prvo vzor čno mesto (R1) je bilo izbrano poleg
izvira, drugo in tretje vzor čno mesto (R2, R3)
sta bili izbrani v osrednjem delu reke, zadnje
vzor čno mesto (R4) pa je bilo izbrano v bližini
2. STUDY SITES
 With its 14 km of length, the Rižana River
(Fig. 1) drains a watershed area of 204.5 km
2
.
The Rižana River features karstic hinterland
with predominantly flysch area, with the
estuary in the Adriatic over brackish wetland.
Typical of the area is a relatively mild
submediterranean climate with mild winters
and relatively high summer temperatures
occurring primarily from the beginning of May
until the end of September. During this period
droughts are quite frequent. The average levels
of annual precipitation amount to
approximately 1000 mm in the coastal area,
whereas in the upper stream area of the Rižana
River they reach approximately 1150 mm. The
annual precipitation distribution is uneven,
meaning that in summer the precipitation takes
the form of heavy showers during which the
water drains and evaporates very quickly.
The Rižana River has been the source of
water supply since 1935. Directly below the
accumulation there is a water abstraction for
the fish-farm and irrigation requirements.
There are further 15 water abstractions
downstream, and in summer some
uncontrolled water abstractions for irrigation.
Consequences can be observed primarily in the
summer period when, due to the deterioration
of the aquatic environment, there were several
cases of fish kill. Downstream, numerous
hydrotechnical interventions were carried out,
too.
Along the watercourse, the riverbed
structure is characterised by various substrates
which, upstream, are composed of large stones
while downstream, the stone structure changes
from gravel into silt. As regard the fish
management, the Rižana River has a status of
a sports and fishing water body, whereas mill-
brooks along the river are listed as
environmentally protected areas for the
sustainable fish-hatching of marble trout
Salmo marmoratus. In the vicinity of the river,
the communities of Ostryo - Quercetum
pubescentis, Carici humulis - Centaureetum
rupestris and Bromo - Chrysopogonetum grylli
are to be found quite frequently. The riparian
vegetation along the watercourse is quite
degraded due to land cultivation and vicinity
of roads.
Four relevant sampling sections of the
Rižana River have been selected: the first (R1)
was selected near the spring, the second (R2)
and third (R3) were selected in the middle part
of the Rižana River and the last (R4) was

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
132
izliva v Jadransko morje.
Zaledje reke Rižane je pretežno kraško z
zna čilnimi hidrogeološkimi pojavi, kar se kaže
tudi v letnih hidrogramih. Koli čina vode v
Rižani je odvisna od vodostaja podtalnice,
padavin in vodnatosti pritokov Rižane. Pritoki,
ki se nahajajo na kraškem svetu, so kratki in
strmi z zna čilnostmi hudournikov, ki se v
poletnem času izsušijo (Peroša et al., 1993).
Manjši odvzemi vode ob reki v času visoke
vode (tj. spomladi in jeseni) bistveno ne
spreminjajo hidrologije reke, medtem ko se v
sušnem obdobju koli čina vode zmanjša zaradi
prej omenjenih odvzemov vode.
Eden od poglavitnih parametrov pri
dolo čanju ekološko sprejemljivega pretoka so
vrednosti pretokov vode. Koli čina vode se
nanaša na merilno postajo Kubed, ki se nahaja
pod odvzemom za sistem oskrbe s pitno vodo,
katerega maksimalna koli čina znaša 0,35 m
3
/s.
Hidrološke zna čilnosti pretokov reke Rižane
na merilni postaji Kubed za obdobje 1966–
1995 so predstavljene v preglednici 1.
selected in the very vicinity of its estuary in
the Adriatic Sea.
The hinterland of the Rižana River is
primarily composed of karst characterised by
specific hydrogeological features, which is
reflected by the annual hydrographs. The
quantity of water feeding the Rižana River
depends on the water-level of the groundwater,
the precipitation and the capacity of the Rižana
River tributaries. The tributaries of the river,
located in the karst region, are short and steep,
having all the characteristics of torrents drying
in summer periods (Peroša et al., 1993). Minor
water abstractions along the watercourse
during the period of high flows (i.e. in spring
and autumn) do not essentially change the
hydrology of the river, whereas in drought
periods the water quantity along the
watercourse decreases due to the mentioned
abstractions.
One of the basic parameters in estimating
EAF are the flow values. The water quantity
data refer to the Kubed gauge station, which is
located below the abstraction for water supply
system, whose maximum delivery amounts to
0.35 m
3
/s. The hydrological characteristics of
the Rižana River flows at the Kubed gauge
station for the thirty year period (1966–1995)
are represented in Table 1.
Slika 1. Reka Rižana.
Figure 1. The Rižana River.

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
133
Preglednica 1. Hidrološki podatki za reko Rižano na merilni postaji Kubed za obdobje 1966–1995.
Table 1. Hydrological data for the Rižana River at the gauge station Kubed, for period 1966–1995.
Parameter/parameter Vrednost/value
prispevno obmo čje/catchment area 204.5 km
2
srednji letni pretok/mean annual flow 4.101 m
3
/s
srednji minimalni pretok/mean minimum flow 0.222 m
3
/s
minimalni pretok/minimum flow 0.010 m
3
/s
Q300d 0.500 m
3
/s
Q347d 0.160 m
3
/s
3. MATERIALI IN METODE
Na štirih vzor čnih mestih (R1, R2, R3, R4)
reke Rižane so bili za kvantitativne in
kvalitativne analize odvzeti vzorci (do štirje
odvzemi) perifitona in ve čjih vodnih
nevreten čarjev. Vzorci so bili pobrani na 4
to čkah vzor čnega mesta v pre čnem profilu.
Ozna čeni so bili kot R1.1–R1.4 od levega proti
desnemu bregu.
Kvantitativne vzorce vodnih nevreten čarjev
smo zbrali z vzorčevalnikom Surber
(pravokotnik 21,5 krat 17,5 cm, z velikostjo
okenca 0,3 mm). Vzorce perifitona in ve čjih
vodnih nevreten čarjev smo konzervirali na
terenu s 36-odstotnim formaldehidom in jih
prenesli v laboratorij na sortiranje. Kjer je bilo
mogo če, so bili ve čji vodni nevreten čarji
dolo čeni do nivoja vrste, medtem ko se je pri
ve čini dolo čil le rod, v nekaterih primerih pa le
družina. Ve čina perifitonskih alg je bila
dolo čena do nivoja vrste. Po pregledu
organizmov se je ocenila pogostost
posameznih vrst perifitonskih alg in ve čjih
vodnih nevreten čarjev, to pa se je ozna čilo z 1
– redko, posamezno, 3 – srednje pogosto, 5 –
pogosto, množi čno.
Vzorci perifitona, namenjeni za
kvantitativno analizo perifitonske biomase, so
bili odvzeti iz re čnih sedimentov, premera 50–
200 mm. Na vsaki to čki vzor čnega mesta smo
postrgali 5 plavin, in sicer smo iz vsake
postrgali površino 200 mm
2
. V laboratoriju
smo ovrednotili suho težo in organsko snov
(suha teža brez pepela) po metodiki
APHA.AWWA.WPC (1992). Koncentracijo
klorofila-a smo dolo čili s filtracijo skozi filtre
Watman GF/C in z ekstrakcijo z vro čim
3. MATERIALS AND METHODS
In four sampling sections (R1, R2, R3, R4)
of the Rižana River, up to four samples of
periphyton and macroinvertebrates were taken
for quantitative and qualitative analyses. The
samples were taken at 4 sampling points in the
sampling section in a river cross-section. They
were designated f.e. R1.1–R1.4 from the left to
the right bank.
Quantitative samples of macroinvertebrates
were collected with the Surber sampler (square
21.5 by 17.5 cm, mesh size 0.3 mm). The
samples of periphyton and macroinvertebrates
for qualitative analyses were preserved in the
field with 36 % formaldehyde and returned to
the laboratory for sorting. Where possible,
some macroinvertebrates were identified to
species level, whereas the majority was
identified to genus level, and in few cases only
to family level. The majority of periphytic
algae taxa were identified to species level.
After surveying the organisms, abundance of
individual taxa of algae and
macroinvertebrates was assessed, marked by 1
– rare, occasional, 3 – frequent, 5 – dominant.
 Periphyton samples intended for
quantitative analysis of the periphyton biomass
were taken from river sediments 50 mm to 200
mm in diameter. At each sampling point in the
sampling section, 5 sediment particles were
scraped off from the surface 200 mm
2
. Dry
weight (DW) and organic matter (ash-free dry
weight – AFDW) were assessed in the
laboratory using the APHA.AWWA.WPC
technique (1992). The chlorophyll-a
concentration was determined by the use of
filtration through Watman GF/C filters and

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
134
metanolom (Vollenweider, 1974). Vrednosti
perifitonske biomase so bile izra čunane za
kvadratni meter substrata na re čnem dnu.
Vzor čevanje je na vseh odvzemnih mestih
potekalo v obdobju nizkega pretoka, tj. poleti
1996 in pozimi 1997.
V obdobju vzor čevanja se je na odvzemnih
mestih merilo pretoke in maksimalno hitrost
pretoka z merilcem pretoka SEBA Mini
Current Meter MI.
Razlike v povpre čnih vrednostih suhe teže,
organske snovi in klorofila-a smo testirali med
vzor čnimi mesti. Z izra čunom Bray-
Curtisovega koeficienta podobnosti (Clarke &
Warwick, 1990) so se ocenile podobnosti med
posameznimi mesti s pomo čjo podatkov
vrstnega sestava in pogostosti prisotnih vrst.
Delež primanjkljaja vrst po Kothéju 1962
(Wegl, 1983) je bil izra čunan iz števila
perifitonskih alg in skupin ve čjih vodnih
nevreten čarjev v vzorcih na posameznih
mestih reke.
Ocena kakovosti vode je bila ovrednotena s
Pantle-Buckovim saprobnim indeksom s
prilagoditvijo metodi, ki sta jo razvila Zelinka
in Marvan (1961). Kakovost vodnega okolja je
bila ocenjena z ocenjevalno lestvico BMWP
(Armitage et al., 1983) in EBI (spremenjeno
po Ghetti, 1986).
extraction with hot methanol (Vollenweider,
1974). The values of periphyton biomass were
calculated per square metre of river bottom
substrata. In all sections, samples were taken
in the period of low flow in summer 1996 and
in winter 1997.
During the sampling period, the flow and
the maximum current velocity in the sections
were measured by SEBA Mini Current Meter
MI.
The differences in AFDW averages, DW
averages and chl-a averages were tested
between sampling sections. By calculating the
Bray-Curtis coefficient of similarity (Clarke &
Warwick, 1990), the similarities between
individual sections were evaluated as far as
species diversity and their abundance were
concerned.
A percentage of species deficit by Kothé,
1962 (Wegl, 1983) was calculated from the
number of periphytic algae and
macroinvertebrates taxa in samples between
individual sampling sections of the river.
The quality of water was evaluated using
the Pantle-Buck saprobic index with
modification to the Zelinka and Marvan
method (1961). The quality of aquatic
environment was evaluated by BMWP score
system (Armitage et al., 1983), and Extended
Biotic Index – EBI (modified by Ghetti, 1986).
4. REZULTATI IN RAZPRA V A
4.1 HITROST TOKA IN PRETOK
Poleti 1996 se je pretok vzdolž reke
zmanjšal zaradi odvzema vode za namakanje
in industrijo ter zaradi naravnega pronicanja v
podtalje kot posledice intergranularne
poroznosti substrata. Podobno tudi rezultati
meritev 6. oktobra 1995 (Vrhovšek et al.,
1995) kažejo naslednje vrednosti pretokov
vode: na vzor čnem mestu R1 smo izmerili
pretok 1,036 m
3
/s in na vzorčnem mestu R4
0,836 m
3
/s. Pozimi 1997 se je pretok
pove čeval od vzor čnega mesta R1 proti
vzor čnemu mestu R4. Maksimalna povpre čna
hitrost je bila vedno najvišja v obmo čju R1;
najnižja je bila poleti 1996 v obmo čju R4
(slika 2). Rezultat naravnih in antropogenih
posegov, ki so povzro čili spremembe pretoka
4. RESULTS AND DISCUSSION
4.1 CURRENT VELOCITY AND
DISCHARGE
The discharge in summer 1996 decreased
along the river as a result of water abstraction
for irrigation, industry and natural drainage
into underground due to intergranular porosity
of substrata. Similarly, the results of the
measurements carried out on October 6, 1995
(Vrhovšek et al., 1995) indicated the following
values of the water flow: R1 section 1.036
m
3
/s and R4 section 0.836 m
3
/s. In winter
1997, the discharge increased from section R1
to section R4. Maximum mean velocity always
reached its highest value in the R1 section; the
lowest was in summer 1996 in the R4 section
(Fig. 2). The result of natural and
anthropogenically induced changes in

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
135
poleti, je skoraj popolnoma suha re čna struga.
Re čno strugo sestavlja pretežno trden substrat
(velike in manjše skale, prodniki) kot
posledica nizkega pretoka in hitrosti toka
vzdolž reke; dolvodno so predvsem v obmo čju
počasnejšega toka pogostejši drobni sedimenti.
Pri dolo čanju ekološko sprejemljivega pretoka
mora biti zagotovljena odstotnost ekstremnih
nanosov drobnih sedimentov, potrebno pa je
periodi čno vzdrževanje visoke vode in
raznolikost v hitrostih vodnega toka v
vodotoku kot tudi vzdrževanje dolo čenega
vodostaja (Bundi & Eichenberger, 1989).
Treba je tudi ohraniti pestrost v razli čnih tipih
vodnih habitatov na posameznih odsekih rek.
discharge in summer is a nearly dry river bed.
As a consequence of low discharge and current
velocity along the river, the river bed in the R1
and R2 sections is dominated by solid
substrates (boulders, rocks and pebbles),
whereas downstream soft sediments frequently
occur in low current sections. The
determination of EAF requires the absence of
the extreme accumulation of small sediments
and the periodical maintenance of high water
flows and the diversity of watercourse
velocity, as well as the maintenance of the
specific water level (Bundi & Eichenberger,
1989). It is important to ensure the diversity in
various types of water habitats within the river
sections.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
R1 R2 R3 R4
section
discharge (m
3 
s
-1
)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
max mean velocity (m s
-
1
)
discharge August 1996 discharge February 1997
max mean velocity August 1996 max mean velocity February 199
Slika 2. Pretok in maksimalna hitrost na vzor čnih mestih reke Rižane.
Figure 2. Discharge and maximum velocity for the sampling sections in the Rižana River.
4.2 BIOMASA PERIFITONA
V primerjavi z dolvodnimi odvzemnimi
mesti so bile najvišje vrednosti suhe teže,
organske snovi in klorofila-a izmerjene na
vzor čnem mestu R1, tj. predvsem poleti 1996
(preglednica 2).
4.2 PERIPHYTON BIOMASS
In comparison with downstream sites, the
highest values of DW, AFDW and chl-a were
measured in the R1 sampling section, notably
in summer 1996 (Table 2).

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
136
Preglednica 2. Minimalne (min), maksimalne (max) in povpre čne (ave) vrednosti suhe teže
(DW), organske snovi (AFDW) in klorofila-a (Chl-a) na vzor čnih mestih v reki Rižani.
Table 2. Minimum (min), maximum (max) and average (ave) values of DW, AFDW
and chl-a for the sampling sections in the Rižana River.
DW (g/m
2
) AFDW (g/m
2
) Chl-a (mg/m
2
)
min max ave min max ave min max ave
R1 152 327 237 30 181 86 191 773 374
R2 44 220 139 13 78 44 65 329 200
R3 19 227 140 5 79 42 10 218 113
R4 125 210 172 5 34 19 96 181 146
Predpostavljamo lahko, da je razloge
potrebno iskati v negibljivem sedimentu, v
morfološki raznolikosti re čne struge in v
prevladi zelenih alg. Najnižje vrednosti
perifitonske biomase so bile izmerjene na
vzor čnem mestu R3 kot posledica drobnega
gibljivega substrata, ki onemogo ča razvoj
stabilnih perifitonskih združb. Podobni pogoji
so bili 10. junija 1995 ugotovljeni na
vzor čnem mestu R4 (suha teža = 780 g/m
2
),
kjer je bilo onesnaženje vode še ve čje. Zaradi
vpliva drugih okoljskih dejavnikov velike rasti
alg ni bilo mogo če pojasniti samo na podlagi
pretoka vode, temve č tudi z visoko vrednostjo
hranilnih snovi, vplivom svetlobe in ve čjimi
sedimentnimi zrni (Smolar – Žvanut, 2001).
Vrednosti perifitonske biomase so bile pozimi
1997 nižje kot poleti 1996; podobno je bilo
tudi na drugih slovenskih vodotokih: na
Tržiški Bistrici, Dravinji in Branici (Smolar et
al, 1998), Savi Bohinjki (Kosi, 1988) in So či
(Smolar – Žvanut, 2001). Pozimi 1997 so bile
izmerjene zelo nizke vrednosti organske snovi
na vzor čnih mestih R3 in R4 (5 g/m
2
), medtem
ko je bila najnižja vrednost klorofila-a
izmerjena na vzor čnem mestu R3 (10 mg/m
2
).
S 95-odstotno verjetnostjo lahko potrdimo, da
so bile povpre čne vrednosti klorofila-a pozimi
1997 statisti čno bistveno druga čne med
vzor čnimi mesti R1 in R3 ter med R1 in R4 (p
< 0,05). Povpre čne vrednosti organske snovi
so se poleti 1996 statisti čno bistveno
razlikovale med vzor čnimi mesti R1 in R2 ter
med R1 in R3 (95-odstotna verjetnost). Pri
dolo čanju ekološko sprejemljivega pretoka je
potrebno poznavanje naravne dinamike
pojavljanja biomase perifitona. V obdobju
We may assume that the reason for this
phenomenon can be found in stable sediments,
in the morphological diversity of the river bed
and in the predominance of green algae mats.
The lowest values of periphyton biomass were
measured in the R3 section as the result of
small moving substrata, which disable the
development of a stable periphyton
community. The same conditions were
established in the R4 section, where water
pollution was higher. The periphyton biomass
was very high on river substrata in the R4
section measured on 10 June 1995 (i.e. DW =
780 g/m
2
). Due to the impact of other
environmental factors, it was not possible to
explain the massive growth of algae only
through the low level of water flow, but also
through the high nutrient level, impact of light
and large sediment grains (Smolar – Žvanut,
2001). The values of periphyton biomass were
lower in winter 1997 than in summer 1996; the
same was the case of the Slovenian streams
Tržiška Bistrica, Dravinja and Branica (Smolar
et al, 1998), Sava Bohinjka (Kosi, 1988) and
So ča (Smolar – Žvanut, 2001). Very low
values of AFDW (5 g/m
2
) were measured in
winter 1997 in the R3 and R4 sections, while
the lowest value of chl-a was measured in the
R3 section (10 mg/m
2
). With 95 % of
probability we can affirm that in winter 1997
the average values of chl-a were statistically
significantly different between the R1 and R3,
and between R1 and R4 sections (p < 0.05).
The average values of AFDW in summer 1996
differed statistically significantly between the
R1 and R2 sections and between the R1 and
R3 sections (95 % of probability). The
knowledge of the natural dynamics of
periphyton biomass in determining the EAF
should be known. In the period of low flow

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
137
nizkih pretokov vode je namre č potrebno
zagotavljati koli čino in kakovost vode, da ne
pride do prevelikega preraš čanja dna s
perifitonskimi algami.
4.3 PERIFITONSKE ALGE IN VE ČJI
VODNI NEVRETEN ČARJI
V reki Rižani smo poleti 1996 dolo čili 70
taksonov perifitonskih alg, pozimi 1997 pa 58
taksonov. Ve čina taksonov je pripadala
skupini diatomej (Bacillariophyta), vrste iz
skupin Cyanophyta, Chlorophyta,
Xanthophyta in Rhodophyta pa so se pojavljale
redkeje, podobno kot na primer v kraški reki
Unici (Vrhovšek et al., 1996). Na vzor čnih
mestih so bile prisotne alge, ki so splošno
razširjene, medtem ko sta bili na vzor čnem
mestu R1 poleti 1996 množi čno prisotni vrsti
Tribonema vulgare in Microspora amoena, ki
sta zna čilni predstavnici za čiste reke. Rod
Batrachospermum je v slovenskih rekah manj
pogost in smo ga našli le na vzor čnih mestih
R1 in R2. Zaradi sprememb morfologije in
pretoka v reki Rižani so bile na vzor čnih
mestih R3 in R4 pogostejše epipeli čne in
epizamne alge kot v obmo čjih R1 in R2, kjer
so prevladovale epilitske alge. Če bi v reki
vzdrževali raven ekološko sprejemljivega
pretoka, do tako velikih sprememb v
perifitonski združbi ne bi prihajalo.
Ve čina od 61 skupin ve čjih vodnih
nevreten čarjev je bila prisotna na vzor čnih
mestih R1 in R2. V vsakem vzorcu smo
dolo čili ve č kot 30 taksonomskih skupin, na
obmo čju R3 in R4 pa je bilo število skupin na
vzorec nižje (od 10 do 24), z izjemo zime
1997, ko je bilo na vzor čnem mestu R4 v
vzorcu najdenih 35 taksonov ve čjih vodnih
nevreten čarjev.
Prevladujo če taksonomske skupine ve čjih
vodnih nevreten čarjev na vzor čnih mestih v
obeh letnih časih so bile vrste Gammarus
fossarum, rod Baetis, družina Elmidae. Rod
Baetis je prevladoval na vseh vzor čnih mestih,
z izjemo poletja 1996, ko ga na vzor čnem
mestu R3 in R4 nismo našli.
Dolvodno je števil čnost narasla le pri
taksonomskih skupinah Oligochaeta iz družine
Lumbriculidae in Tubificidae.
such quantity and quality of water should be
assured in the river, so that there is no
proliferation of periphytic algae on the
riverbed.
4.3 PERIPHYTIC ALGAE AND
MACROINVERTEBRATES
A total of 70 taxa of periphytic algae were
recorded in summer 1996, and 58 taxa in
winter 1997 in the Rižana River. The majority
of them belonged to Bacillariophyta, whereas
the species of Cyanophyta, Chlorophyta,
Xanthophyta and Rhodophyta were less
pronounced, e.g. in the karst river Unica
(Vrhovšek et al., 1996). Periphytic algae found
in sections discussed consisted of several
frequently occurring species, while in the R1
section, Tribonema vulgare and Microspora
amoena were dominant in summer 1996. Both
species are representatives for unpolluted
rivers. The genus of Batrachospermum is less
frequent in the Slovenian rivers and it was
found only in the R1 and R2 sections. Because
of the morphological and discharge changes in
the Rižana River in the R3 and R4 sampling
sections, epipelic and epipsamic algae were
more frequent compared to the R1 and R2
sections, where epilithic algae were dominant.
Had the EAF in the river been maintained,
such major changes in periphyton community
could not occur.
The majority of 61 taxa of
macroinvertebrates were present in the R1 and
R2 sections. We found more than 30 taxa in
each sample in the first two sampling sections,
while on other two sites the number of taxa per
sample was lower (from 10 to 24), with the
exception of R4 featuring 35 taxa of
macrozoobenthos in winter 1997.
The dominant taxa of macroinvertebrates in
the sections in both seasons were species
Gammarus fossarum, genus Baetis and family
Elmidae. The genus Baetis was dominant in all
sections, except in summer 1996 in the R3 and
R4 sections when it was not found.
The only taxa whose abundance increased
downstream were Oligochaetes from families
Lumbriculidae and Tubificidae.
The average density of Gammarus
fossarum increased downstream from 25.4 per

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
138
Povpre čna gostota vrste Gammarus
fossarum je poleti 1996 dolvodno narasla s
25,4 na vzorec na vzor čnem mestu R1 na 277
na vzor čnem mestu R3 in se rahlo znižala na
vzor čnem mestu R4. Povpre čna gostota
taksonov Ephemeroptera se je pozimi 1997
zmanjšala dolvodno (z 99 na vzor čnem mestu
R1 na 0 na vzor čnem mestu R3), gostota pa je
bila najvišja na vzor čnem mestu R4 (rod
Baetis). Gostota Coleoptera je bila najvišja na
R2 pozimi 1997 in na R1 poleti 1996; v obeh
primerih je bila najnižja gostota na vzor čnem
mestu R3.
Zaradi zmanjšanja pretoka in nizke
kakovosti vodnega okolja vzdolž reke smo
poleti 1996 zabeležili velik primanjkljaj
skupin ve čjih vodnih nevreten čarjev
(preglednica 3). Tako je imelo poslabšanje
kakovosti vodnega okolja velik vpliv na
združbo ve čjih vodnih nevreten čarjev. V istem
času vzor čevanja pa primanjkljaj v številu
taksonov perifitonskih alg ni bil velik; na
vzor čnih mestih R2 in R3 je bilo najdenih ve č
vrst kot na referen čnem mestu R1 (preglednica
3). Podobni so bili rezultati raziskav na Tržiški
Bistrici (Smolar, 1997), kjer v strugi, ki je bila
pod vplivom odvzema vode ni bilo sprememb
v številu vrst. Pozimi 1997 smo opazili ve čji
primanjkljaj vrst perifitonskih alg na vzor čnih
mestih R2 in R3. Kljub zelo nizkemu pretoku
vode poleti 1996 na vzor čnem mestu R4 ni
bilo primanjkljaja v številu taksonov
perifitonskih alg, kar kaže na slabost
uporabljenega indeksa, saj ta ne poda evidence
o strukturnih spremembah, ki se ne odražajo v
zmanjševanju števila taksonov perifitonskih
alg.
Bray-Curtisov koeficient podobnosti (slika
3) je pokazal veliko podobnost med vzorci, ki
so bili pozimi 1997 odvzeti na vzor čnih mestih
R1, R2 in R4. Dokaj nizko število vrst in
velika podobnost med poletnimi in zimskimi
vzorci na vzor čnem mestu R3 je verjetno
odraz gibljivega substrata manjše velikosti, ki
ne omogo ča naselitve ve čjega števila
perifitonskih alg in ve čjih vodnih
nevreten čarjev. Pozimi 1997 je bilo vzor čno
mesto R4 bolj podobno vzor čnima mestoma
R1 in R2 kot vzor čnemu mestu R4 poleti
1996.
sample in the R1 section to 277 in the R3
section in summer 1996. In winter 1997, the
difference decreased from 64 in the R1
sampling section to 111 in the R3 section, and
was slightly reduced in the R4 section. The
average density of Ephemeroptera decreased
downstream in winter 1997 (from 99 in the R1
sampling section to 0 in the R3 section), while
the density reached its maximum in the R4
section (genus Baetis). The density of
Coleoptera was at its highest in the R2 section
in winter 1997 and in the R1 section in
summer 1996; the lowest density was in both
cases in the R3 sampling section.
Due to the reduction in discharge and a low
quality of aquatic environment along the river
in summer 1996, a high deficit of
macroinvertebrates taxa was recorded (Table
3). Consequently, a lower quality of aquatic
environment had a large effect on the
macroinvertebrate community. The deficit in
the number of taxa of periphytic algae at the
same sampling time was not high; in the R2
and R3 sampling sections more species were
determined than in the R1 reference section
(Table 3). Similar were the result of the
investigations of the river Tržiška Bistrica
(Smolar, 1997), where no changes in the
number of species were observed in the river
section, which was effected by water
abstraction. In winter 1997, a higher species
deficit of periphytic algae in the R2 and R3
sections was detected. In spite of a very low
water flow in the R4 section in summer 1996,
there was no deficit of periphytic algae,
indicating the deficiency of the applied index,
as the latter does not provide for the evidence
on the structural changes, including the
reduction of the number of taxa of periphytic
algae.
The Bray-Curtis coefficient of similarity
(Fig. 3) showed high similarity between the
samples found in sections R1, R2 and R4 in
winter 1997. A relatively small number of
species and a high similarity between the
summer and winter samples of the R3 section
is probably the reflection of a small-sized
moving substrata, which do not allow for the
colonisation of a large number of periphytic
algae and macroinvertebrates. In winter 1997,
the R4 section was more similar to sections R1
and R2 than to the R4 section in summer 1996.

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
139
Preglednica 3. Kothéjev indeks za primerjavo vzor čnih mest R2, R3 in R4
z referen čnim vzor čnim mestom R1.
Table 3. Kothé index for comparison of the sampling sections R2, R3 and R4
with the reference sampling section R1.
Datum/
Date
Vzor čno
mesto/
Sampling
section
Število vrst
perifitonskih
alg /
Number of
periphytic
algae species
Odstotek
primanjkljaja
vrste /Percent
of species
deficit (%)
Število skupin
vodnih
nevreten čarjev
/Number of
macroinvertebrate
taxa
Odstotek
primanjkljaja
taksona /Percent
of taxa deficit (%)
26. 8. 1996 R1 43 30
R2 57 –24.6 37 –23.3
R3 37 14.0 10 66.7
R4 45 –4.7 16 46.7
18. 2. 1997 R1 41 37
R2 31 24,4 36 2.7
R3 31 24.4 24 35.1
R4 38 7.3 35 5.4
Slika 3. Bray-Curtisov koeficient podobnosti za vzorce ve čjih vodnih nevreten čarjev in
perifitonskih alg v reki Rižani poleti 1996 (S96) in pozimi 1997 (W97).
Figure 3. Bray-Curtis coefficient of similarity for samples of macroinvertebrates and periphytic
algae in the Rižana River in summer 1996 (S96) and in winter 1997 (W97).

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
140
4.4 KAKOVOST VODE
Vrednosti saprobnega indeksa (SI) so
vzdolž reke rahlo narasle, kljub temu pa je bila
reka na vseh vzor čnih mestih uvrš čena v I.–II.
kakovostni razred. Podobni so bili rezultati
raziskav na vzor čnem mestu R4 leta 1995
(Vrhovšek et al., 1995). Primerjava rezultatov
rednega državnega programa monitoringa na
vzor čnem mestu R2 in dolvodno od vzor čnega
mesta R4 med letoma 1987 in 1993 (Peroša et
al., 1993) je pokazala višje vrednosti
saprobnega indeksa pod obmo čjem R4, kar
reko pod tem mestom uvrš ča v II.–III.
kakovostni razred.
Poleti 1996 sta bili vzor čni mesti R3 in R4
na podlagi vrednosti EBI (slika 4) uvrš čeni v
IV. kakovostni razred, medtem ko bi obmo čji
R3 in R4 na podlagi vrednosti BMWP (slika 5)
lahko uvrstili v V. razred. Tako indeks BMWP
kot indeks EBI sta pozimi 1997 kazala nižjo
kakovost vodnega okolja na vzor čnih mestih
R3 in R4. Na podlagi tako dobljenih podatkov
lahko sklepamo, da indeksa EBI in BMWP
kažeta na poslabšanje kakovosti vodnega
okolja, indeks SI pa kaže stopnjo
onesnaženosti vode. Podobni so bili tudi
rezultati analiz reke Dravinje (Krušnik &
Černa č, 1996).
5. ZAKLJU ČKI
Z ozirom na odvzeme vode za potrebe
oskrbe z vodo so rezultati hidroloških analiz
pokazali, da je bil zaradi izjemno velikega
odvzema vode vzdolž vodotoka in
intergranularne poroznosti substrata v
spodnjem delu reke Rižane pretok vode v
poletnih mesecih zelo nizek. To se je odražalo
v poslabšanju vodnega okolja. Upoštevajo č
hidrološke, ekološke, krajinske, morfološke in
ihtiološke zna čilnosti in na podlagi ocene
habitatov smo predlagali vrednosti ekološko
sprejemljivega pretoka za poletno sušno
obdobje 0,160 m
3
/s, kar bi – ob zmanjšanju
onesnaženja – omogo čilo ohranjanje
ekološkega ravnovesja tako v reki kot v
obrežnem prostoru.
4.4 WATER QUALITY
The values of saprobic index (SI) slightly
increased along the river, nevertheless it was
classified in all sampling sections as quality
class I–II. Similar were the results of the
investigations in the R4 section in 1995
(Vrhovšek et al., 1995). The comparison of the
results of the regular National Monitoring
Programme in the R2 and below R4 section
between 1987 and 1993 (Peroša et al., 1993)
showed higher values of the saprobic index
below R4 section, thus classifying the river
below this section into the II–III quality class.
In summer 1996, the EBI values (Fig. 4)
classified sampling sections R3 and R4 into
quality class IV, whereas, based on the BMWP
values (Fig. 5) the R3 and R4 sections could
be classified as quality class V. Both the
BMWP and EBI indices showed in winter
1997 a lower quality of the aquatic
environment in the R3 and R4 sections. Based
on the results thus obtained we may conclude,
that the EBI and BMWP indices indicate the
deterioration of the aquatic environment
quality, while the SI shows the pollution
degree of water. Similar results were obtained
in analysing the Dravinja River (Krušnik &
Černa č, 1996).
5. CONCLUSIONS
With regard to the water abstraction for the
water supply purposes, the results of the
hydrological analyses showed that due to
extremely high water abstractions along the
watercourse and the intergranular porosity of
substrata in the lower part of the Rižana River,
the flows were very low during the summer
period. This has been reflected in the
deterioration of the aquatic environment.
Taking into consideration the hydrological,
ecological, landscape, morphological and
ichthyological characteristics and habitat
evaluation, we proposed the EAF values for
the dry summer period amounting to 0.160
m
3
/s, which, by reducing the pollution level,
will enable the maintenance of the ecological
balance both in the river and in the riparian
zone.

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
141
EBI vs SI
0
2
4
6
8
10
12
R1 R2 R3 R4
EBI
1
1.5
2
2.5
3
3.5
4
SI
EBI 96 EBI 97 SI 96 SI 97
Slika 4. Vrednosti EBI v primerjavi z vrednostmi SI za reko Rižano.
Figure 4. The values of EBI in comparison with the values of SI for the Rižana River.
0
20
40
60
80
100
120
140
160
R1 R2 R3 R4
BMWP
1
1.5
2
2.5
3
3.5
4
SI
BMWP 96 BMWP 97 SI 96 SI 97
Slika 5. Vrednosti BMWP v primerjavi z vrednostmi SI za reko Rižano.
Figure 5. The values of BMWP in comparison with the values of SI for the Rižana River.

Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
142
Najpomembnejši ukrepi, ki jih predlagamo,
so racionalna raba vode, iskanje novih virov
pitne vode, čiš čenje voda, nadzorovanje
onesnaženja vode, ocena iztoka vode iz
na črtovane akumulacije in zagotavljanje
ekološko sprejemljivega pretoka.
The rational use of water, search for new
sources of drinking-water, waste water
treatment, control of water pollution,
evaluation of outflow from the planned
accumulation and preservation of the
ecologically acceptable flow are the most
important arrangements that we suggested.
ZAHVALA
Delo je finan čno podprlo Ministrstvo za
okolje, prostor in energijo. Zahvaljujemo se
tudi Petru Mucku in Darku Burji, ki sta
priskrbela hidrološke podatke, in Miljanu
Šišku za opravljene statisti čne analize.
ACKNOWLEDGEMENTS
This work was funded by the Ministry of
the Environment and Physical planning. We
thank Peter Muck and Darko Burja who
provided hydrological data and Miljan Šiško
for statistical analyses.
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Smolar - Žvanut et al.: Uporaba perfitona in makrozoobentosa pri dolo čanju ekološko sprejemljivega pretoka na reki
Rižani, Slovenija – The Use of Periphyton and Macrozoobentos in Determination of Ecologically Acceptable Flow for
the Rižana River, Slovenia
© Acta hydrotechnica 21/35 (2003), 129-144, Ljubljana
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Naslov avtorjev – Authors’ Addresses
dr. Nataša Smolar - Žvanut
LIMNOS d.o.o. – LIMNOS Ltd.
Podlimbarskega 31, SI-1000 Ljubljana, Slovenia
E-mail: natasa@limnos.si
&
Inštitut za vode Republike Slovenije – Institute for Waters of the Republic of Slovenia
Hajdrihova 28, SI-1000 Ljubljana
E-mail: natasa.smolar@guest.arnes.si
dr. Ciril Krušnik
Javni zavod za ribištvo Slovenije – Public Fisheries Institute of Slovenia
Zupan či čeva 9, SI-1000 Ljubljana, Slovenia
E-mail: ciril.krusnik@zzrs.si
dr. Gorazd Kosi
Nacionalni inštitut za biologijo – National Institute of Biology
Ve čna pot 111, SI-1000 Ljubljana, Slovenia
E-mail: gorazd.kosi@nib.si
prof. dr. Danijel Vrhovšek
LIMNOS d.o.o. – LIMNOS Ltd.
Podlimbarskega 31, SI-1000 Ljubljana, Slovenia
E-mail: dani@limnos.si