ECOLOGICAL MONITORING IN THE MONTENEGRIN COASTAL SEA
Dubravka Regner
*
, Nenad Vuksanovic, Branislav Stjepcevic and Danijela Joksimovic
Institute of Marine Biology, Kotor, Serbia and Montenegro - * biokotor@mail.cg.yu
Abstract
Investigations of the sea-water quality and the level of eutrophication in the Montenegrin coastal sea have been continued in 1999-2002
period. The increasing values of some parameters (indicators of eutrophication) as oxygen saturation at the surface and the
microphytoplankton density have been established. The highest eutrophication was found in the inner and middle parts of the Boka
Kotorska Bay, and in the Bojana river mouth. Sanitary quality of the sea was satisfying, yet. About 20% of the beaches in the Bay, and
about 52% outside the Bay were the first category – up to 500 TC/100 ml of the sea-water.
Keywords: sea-water eutrophication, sanitary quality
Rapp. Comm. int. Mer Médit., 37,2004
542
Having in mind the importance of the Montenegrin coastal sea for
tourism and all activities connected with it, the control of the marine
environment and plankton community has been continued after 1998
(1) throughout next four years period. The main intentions were: to
estimate the possible changes caused by eutrophication and to follow
the sanitary quality of the sea. So, the material was taken at same 28
localities in the inner (Kotor Bay), middle (Tivat Bay) and outer part
(Herceg Novi Bay) of the Boka Kotorska Bay, 26 outside the Bay and
one at the Bojana river mouth. Standard methodology was used as
before.
Although about 20 physical, chemical and biological characteristics
have been investigated, only some of them would be presented here,
owing to their importance for classification of the eutrophic level or
sanitary quality of the sea water.
From physical characteristics, only transparency and sea-water
color will be described here.
Transparency varied significantly in comparison with the previous
results. It decreased along (near) the coast very often, at about 30% of
the beaches in the Bay and at about 18% of the positions outside the
Bay – including the Bojana river mouth. Such decreasing was caused
by anthropogenic eutrophication as the consequence of yet unsolved
system of waste- waters discharges and their direct impact to the shal-
lowest coastal sea (2).
Sea-water color was changed in Kotor and Tivat Bays predominant-
ly, to yellowish (XI-XII, XIII-XIV, XV-XVI) or even brownish (XVII-
XVIII, XIX-XX, XXI) according to Forell- Uhle scale. So, the recent
results affirmed that the color of the sea-water was changed occasion-
ally, or usually at some positions in the Boka Kotorska Bay. Outside
the Bay, changes were found rarely , because of direct exposition of
this area to stronger in?uence of unpolluted oligotrophic waters of the
open South Adriatic. The exception was locality at the Bojana river
mouth, as freshwater impact and a lot of organic matter caused
changed color to yellowish and brownish very often (3).
From chemical characteristics, oxygen saturation was measured
between all others. At the whole area of the Montenegrin coastal sea,
values increased at the surface, related to the higher phytoplankton
production. So, mean values from the recent investigations (149-
155.4%), were similar to the maximum values from 1995-1998 peri-
od. Such high values are characteristic of eutrophic and extremely
eutrophic areas. (4).
Eutrophication was visible even more clearly throughout some bio-
logical parameters: composition and biomass of microphytoplankton,
and heterotrophic bacteria. So, in the preceding period, microphyto-
plankton biomass increased to maximum values of 4.4 x 10
6
cells dm
-3
and even 10
7
cells dm
-3
or more, in the Kotor Bay (throughout sum-
mer, especially). Outside the Bay, up to 10
5
cells dm
-3
were found,
with the exception of the Bojana river mouth, where 8 x 10
5
cells dm
-3
were established. Maximum values were always presented during
summer everywhere, although usual spring and autumn maxima have
been existed, yet (5). Dominant species were: Chaetoceros affinis,
Sceletonema costatum, Nitzschia seriata, Nitzschia delicatissima,
Leptocylindrus danicus, and eleven other species, indicator of
eutrophic coastal sea. Their number was the highest in the Boka
Kotorska Bay, and decreased outside the Bay to seven or eight
species. Sometimes (in summer, too) Sceletonema costatumappeared
in the Kotor Bay with maximum percentage of 55.5% among all other
microphytoplankton species, while Nitzschia delicatissima was pre-
sented with 25.5% of the whole microphytoplankton density, simulta-
neously (6). In the area outside the Bay the percentage of above men-
tioned species decreased as their density, too. Nevertheless, through-
out summer 2001, even in this part of the Montenegrin coastal sea
microphytoplankton density was high enough to overtake values of
eutrophic regions.
The density of heterotrophic bacteria varied in four years period to
maximum values of 10
4
/ml of the sea-water in the Boka Kotorska
Bay, and 2.1 x 10
4
/ml in the Bojana river mouth. In the area outside
the Bay, values were between 10
2
and 1.9 x 10
3
/ml of the sea-water.
All these values are typical for eutrophic areas.
The recent investigations of the sanitary quality (bacterial pollu-
tion) of the coastal sea have been performed at the same well known
beaches of the Montenegrin coast as before. From 28 localities in the
Boka Kotorska Bay, the first category of the sea-water quality (up to
500 total coliforms/100 ml of the sea and up to 100 faecal col-
iforms/100 ml of the sea) was found at 20% of them (7). Second cat-
egory (up to 10000 total coliforms/100 ml of the sea and up to 2000
faecal coliforms/100 ml of the sea) was found at about 72% of inves-
tigated positions. From time to time 8% of them exceeded allowed cri-
teria. Some parts of the Bay (Kotor and Risan Bays in the inner area)
were polluted more (7) and control would be continue with special
attention to this fact. Outside the Bay, at about 52% of the beaches the
first category was found, at 42% of them the second category was pre-
sented, and 6% of them exceeded mentioned criteria.
Conclusion
So, we can conclude that progressive eutrophication was found in
the Montenegrin coastal sea throughout 1999-2002 period. Sanitary
quality of the sea was satisfying, yet.
References
1-Regner, D., N. Vuksanovic, B. Stjepcevic and M. Dutina 2001. The
recent investigations of the sea-water quality in the Montenegrin coastal
sea. Rapp. Comm. int. Mer Médit., 36: 114.
2-Regner, D., N. Vuksanovic, B. Stjepcevic and M. Dutina 2000. The
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