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212 ACTA BOT. CROAT. 79 (2), 2020
Acta Bot. Croat. 79 (2), 212–227, 2020 CODEN: ABCRA 25
DOI: 10.37427/botcro-2020-028 ISSN 0365-0588
eISSN 1847-8476
Colonization of bacteria and diatoms on an articial
substrate in a marine lake (eastern Adriatic Sea, NE
Mediterranean)
Ana Car1, Dubravka Hafner2, Stijepo Ljubimir3, Iris Dupčić Radić1*, Svjetlana Bobanović-Ćolić1,
Nenad Jasprica1
1 University of Dubrovnik, Institute for Marine and Coastal Research, 20000 Dubrovnik, Croatia
2 Bartulovici 4, 20357 Blace, Croatia
3 Matije Gupca 5, 20000 Dubrovnik, Croatia
Abstract –
The initial colonization of bacteria and diatoms on a immersed articial substrate and the develop-
ment of diatom assemblages in relation to physico-chemical parameters were investigated on a weekly basis at
one station in the marine Lake Mrtvo More, South Croatia, from April to October 2016. According to TRIX
trophic index, lake showed dierent trophic character: (i) oligotrophic (at the beginning and the end of the
study), (ii) mesotrophic (the end of June to mid-July), (iii) eutrophic (the end of July to mid-September). Heter-
otrophic bacteria increased to peak abundances (69,268 cells cm–2) at the beginning of June when the diatoms
abundances start to increase. The lake has high diatom species richness (285 diatom taxa within 72 genera),
with the highest species diversity index in August. Among diatoms, adnate were the primary colonizers, par-
ticularly Cocconeis dirupta W.Gregory var. exella (Janisch and Rabenhorst) Grunow and Cocconeis scutellum
Ehrenberg var. scutellum, while motile taxa joined the fouling communities from July to September. This study
showed close relationship between diatom species composition and changes of physico-chemical parameters,
particularly the nutrient concentrations.
Keywords: Bacillariophyta, benthos, biodiversity, Croatia, environmental parameters, heterotrophic bacteria, TRIX
index
Introduction
Any permanently exposed, unprotected surface will
eventually become fouled. The adsorption of macromole-
cules to a surface starts within seconds after immersion, bac-
terial colonization beginning after ca. an hour, and coloni-
zation by unicellular eukaryotes (e.g., diatoms, yeasts, and
protozoa) usually starts several days after immersion (Wahl
1989). Raphid diatoms are generally among the earliest and
most abundant primary colonizers of natural and articial
surfaces (Hoagland et al. 1986). The presence of bacteria and
unicellular algae in the biolm can promote further colo-
nization of the substrate by plants and animals (Totti et al.
2007, and references therein). However, the intensity of foul-
ing pressure varies with season, latitude, depth and local eco-
logical factors (Wahl 1989). Biological, physical and chemi-
cal factors may regulate abundance, distribution and species
composition of diatom communities. Amongst these, sub-
strate characteristics, sampling site location and depth, graz-
ing pressure, and stage of season have been identied as im-
portant factors inuencing the shallow water communities
(Majewska et al. 2016).
Diatom assemblages are widely used as indicators of eco-
logical change in aquatic environments (Ulanova and Snoei-
js 2006). Diatoms are ideal environmental indicators (Dixit
et al. 1992) as they are sensitive to a range of environmental
parameters, including salinity (Roberts and McMinn 1998,
Cunningham and McMinn 2004). The influence of in-
creased nutrient concentration on benthic diatoms became
a subject of scientic investigations when the eutrophication
problem became acute. It became evident that benthic mi-
croalgae exerted a strong inuence on the nutrient ux be-
tween sediment and overlying water (Agatz et al. 1999, and
references therein). Sundbäck and Snoeijs (1991) detected
* Corresponding author e-mail: iris@unidu.hr
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 213
signicant changes in the diatom ora in nutrient enrich-
ment experiments after only 14 days. Results of a study of
diatom diversity at multiple scales in urban reservoirs by
Marra et al. (2018) highlight the key role of nutrient avail-
ability by showing that diatoms grow under very specic
physical and chemical conditions, and eutrophication may
cause community variation.
Marine debris is listed among the major perceived
threats to biodiversity and is cause for particular concern
due to its abundance, durability and persistence in the ma-
rine environment (Gall and Thompson 2015). The materi-
al types most commonly found in marine debris are glass,
metal, paper and plastic (OSPAR 2007). An extensive litera-
ture search has reviewed the current state of knowledge on
the eects of marine debris on marine organisms (Gall and
Thompson 2015, and references therein).
Colonization of articial substrates diers from that of
natural substrates (see Mejdandžić et al. 2015). Comparative
studies have shown that while living (macrophytes) and or-
ganic (wood, leaves) substrates act as additional sources of
nutrients for attached communities, the advent of newly in-
troduced inorganic articial substrates (e.g. glass, plastic) in
the marine environment provides an opportunity to moni-
tor the initial development and the succesion of diatoms in
the periphyton (Nenadović et al. 2015).
Previous studies of fouling by diatoms on articial sub-
strates have been conducted in the northern Adriatic and es-
tuaries (e.g. Tolomio and Andreoli 1989, Tolomio et al. 1991,
Bartole et al. 1991–1994, Burić et al. 2004, Munda 2005, Tot-
ti et al. 2007, Caput Mihalić et al. 2008, Levkov et al. 2010,
etc.). Although Mejdandžić et al. (2015) and Nenadović et
al. (2015) were studied the development of periphytic dia-
toms on dierent articial substrates (plexiglass, asbestos,
painted iron, wood, concrete, glass, plastic, etc.), their re-
sult were mostly based at the generic level. In the Venice
lagoon benthic diatoms were investigated from the surface
sediment layer to investigate a possible relation of epipelic
diatoms with the water quality of shallow coastal areas af-
fected by marked physical and chemical gradients and high
anthropogenic impact (Facca and Sfriso 2007).
In this study, the initial colonization of diatoms in the
periphytic community and the development of diatom as-
semblages on a immersed articial substrate with physico-
chemical properties were examined in a shallow marine lake
during the warmer part of the year, when the ecosystem is
under signicant anthropogenic inuence. We present a
qualitative and quantitative data of the marine benthic dia-
tom communities in order to derive a better understanding
of the multiple interactions that occur between them and
the environment.
The objectives of this study were (i) to determine the
abundances of diatom and bacteria on an articial glass sub-
strate, (ii) to demonstrate their succession through the in-
vestigated period of six months, (iii) to determine the weekly
temporal changes in diatom population structure, and (iv)
to determine the eect of some environmental variables on
the diatom colonization rate in a semi-enclosed marine lake.
Materials and methods
e study area
The experiment was carried out at one station in the
marine Lake Mrtvo More (English: 'Dead Sea', 42°37'21" N,
18°07'14" E) on the island of Lokrum located in front of the
Old City of Dubrovnik, South Croatia (Fig. 1). The island of
Lokrum (72 ha) is a nature reserve and NATURA 2000-Eco-
logical network-site (Site of Community Importance, code:
HR 4000017). Lake Mrtvo More (surface area 1310 m
2
, pe-
rimeter 150 m, max. depth 6 m and average of 2 m) is linked
to the open sea by 15–20 m long underwater tunnel. The lake
is a favourite swimming spot for many visitors during the
summer (On-line Suppl. Fig. 1A).
The region experiences a typical Mediterranean climate:
Summers are warm and dry, and winters are mild and rainy.
Annually, average air temperature is 16 °C and precipita-
tion 1308 mm (data from Dubrovnik meteorological sta-
Fig. 1. Marine Lake Mrtvo More on the island of Lokrum. A – position of the study area on the eastern Adriatic coast, B – location of
Lake Mrtvo More on the island of Lokrum (derived and adapted from Google earth).
CAR A, HAFNER D, LJUBIMIR S, DUPČIĆ RADIĆ I, BOBANOVIĆ-ĆOLIĆ S, JASPRICA N
214 ACTA BOT. CROAT. 79 (2), 2020
tion for 1961–2018, Croatian Meteorological and Hydro-
logical Service). Average temperature during the coldest
month (January) was 9.1 °C, and during the warmest (Au-
gust) 25.2 °C. The highest rainfall is from October to March.
During the dry season (June–August) total rainfall is only
155.4 mm. Average annual wind speed is 3.33 m s
–1
, with the
dominant southerly winds (SE, SSE) blowing from April to
September. Annual potential evapotranspiration is around
1500 mm year
–1
with maximum values in vegetation period
(April-September) (Orešić and Čanjevac 2020). In the area,
the range of diurnal sea-level oscillations is close to 19 cm
(Mihanović et al. 2006). Seawater
surrounded
the island is
under the direct
inuence
of incoming
currents
from the
Ionian
Sea
(Garić and Batistić 2016).
Sampling
The experiment was carried out over a period of 25
weeks from April to October 2016. Water samples for anal-
ysis physico-chemical parameters were taken weekly (On-
line Suppl. Tab. 1) from 19
th
April to 12
th
October, 2016 at
the same place where diatom sampling was carried out, i.e.
at the bottom (1 m depth). Temperature (T) and salinity (S)
were measured using a WTW Multiline P4 multiparametric
sounding lineprobe. Seawater samples for nutrient analyses
(Strickland and Parsons 1972, Ivančić and Degobbis 1984)
and chlorophyll a concentrations (Chl a, Holm-Hansen et al.
1965) were taken by 5 L Niskin bottles. Measured nutrients
included nitrate (NO
3–
), nitrite (NO
2–
), ammonium (NH
4+
),
total inorganic nitrogen (TIN = NO
3–
+ NO
2–
+ NH
4+
), ortho-
phosphate (PO
43–
) and orthosilicate (SiO
44–
).
Samples for NO
3–
, NO
2–
, PO
43–
and SiO
44–
were frozen
(−22 °C) and analysed in a laboratory (Strickland and Par-
sons 1972). Subsamples (50 mL) for NH
4+
were xed im-
mediately after collection with 2 mL of 1 mol L
–1
phenol/
EtOH, kept at 4 °C and later analysed according to Ivančić
and Degobbis (1984). Chl a was determined from 1 L sub-
samples ltered through Whatman GF/F glass-ber lters
and stored at −20 °C for a period of less than a month. Fil-
tered samples were homogenized and extracted in 90% ace-
tone for 24 hours at room temperature (Holm-Hansen et al.
1965). Chl a was determined uorometrically using a Turner
TD-700 Laboratory Fluorometer (Sunnyvale, CA) calibrated
with pure Chl a (Sigma). Due to the exceptionally high Chl
a value of 39 µg L
–1
on 20
th
of July, this record was removed
from further analysis.
Dissolved oxygen was determined by the Winkler
method and oxygen saturation (O
2
/O
2
′) was calculated
from the 100% solubility of oxygen (O
2
) in seawater (Weiss
1970, UNESCO 1973). Trophic status was characterized
by the TRIX index (Vollenweider et al. 1998), common-
ly used to classify coastal marine areas in the Mediterra-
nean (see Primpas and Karydis 2011): TRIX = [log
10
(Chl
a×D%O×DIN×TP)+k]/m. Each of the factors represents a
variable reected in the trophic state: Chl a – chlorophyll a
concentration (µg L
–1
), D%O – dissolved oxygen (absolute
deviation from 100 % oxygen saturation), dissolved inor-
ganic nitrogen DIN and TP – total phosphorus (µg L
–1
). The
parameters k = 1.5 and m = 1.2 set the range of the TRIX
scale from 0 to 10: 0–4 oligotrophic, 4–5 mesotrophic, 5–6
eutrophic, 6–10 extremely eutrophic.
Glass slides were used as a substrate for biolm forma-
tion because of their convenience compared to a natural sub-
strate. The dimensions of a standard microscope slide for
bacteriological and for algological sampling are the same,
measuring about 75 mm by 25 mm and about 1 mm thick.
Microhabitats were made of 33 microscope glass slides
which were arranged in three rows at a distance of approxi-
mately 1 cm and xed on the upper side of a Plexiglas sheet
which was then submerged horizontally with four diving
weights at one station in the lake at a depth of approximate-
ly 1 m (i.e. on the bottom of the Lake Mrtvo More) about 2
m oshore on 19 April 2016 (On-line Suppl. Fig. 1B). Af-
ter three weeks, the Plexiglas sheet was hauled up and the
rst microscopic slide for diatom analysis was removed. Ev-
ery week another microscope slide was taken out and gently
plunged into ltered seawater (Millipore, acetate cellulose
0.22 μm). In total, there were 21 diatom samples (On-line
Suppl. Tab. 1). For bacteriological analysis, 12 glass slides
were collected in a period from 20th May to 6
th
September
(On-line Suppl. Tab. 1). All samples were preserved with 4%
formaldehyde.
Bacteriological analysis
The total number of heterotrophic bacteria was deter-
mined by using a direct counting method counting under
epiuorescent microscopy (Hobbie et al. 1977). All samples
were analyzed within ve days, and before processing were
stored in the dark in a refrigerator at a temperature of about
5 °C. Glass slides were gently brushed and washed with ster-
ile freshly ltered seawater (Millipore, acetate cellulose 0.22
μm) and the biolm was dispersed. For bacteria colouring
a 0.01% solution of acridine orange was used and the 2 mL
subsamples were ltered through Nucleopore lters (pore
diameter of 0.2 µm). Bacterial cells were counted using a Je-
nalumar Zeiss uorescent microscope under 1500´ magni-
cation. These values are expressed as cells per cm
2
.
Diatom analysis
A microscopic glass surface of 1 cm
2
was scraped using
a razor blade, and the microalgae were collected in Falcon
tubes preserved by adding a known amount (3 mL) of solu-
tion (3%) of formaldehyde-ltered seawater (Millipore, ac-
etate cellulose 0.22 μm). Quantitative analysis of homoge-
nized samples was determined with an inverted microscope
(Olympus IX 71) equipped with phase contrast. In these
samples, taxa were not determined. Results are expressed as
total number of diatom cells per cm
2
.
A detailed diatom analysis was performed on perma-
nent slides of processed material (hydrogen peroxide treat-
ed before mounting in Naphrax® as reported by Car et al.
2019) with a Nikon E600 microscope at a magnication of
1000´. The species abundances were expressed as percent-
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 215
ages of the total number of frustules counted (relative abun-
dances, in %). In total, 400 valves per each sample were
counted.
Permanent slides of light microscopy (LM) have been de-
posited in the diatom collection of the Institute for Marine
and Coastal Research, University of Dubrovnik, Dubrovnik,
Croatia. Identications were made following keys and guides
reported by Hafner et al. (2018). Nomenclature follows Al-
gaeBase (Guiry and Guiry 2019).
Statistical analysis
Cluster analysis was used to determine the similarity lev-
el among physico-chemical parameters in samples (Clarke
et al. 2008). A hierarchical clustering algorithm based on
Euclidean distances on log(x+1)-transformed, normalized
data and the average group linkage method were used. The
similarity prole routine (SIMPROF, P < 0.05) were used
to dene the signicantly dierent clusters, and analysis of
similarities (ANOSIM) was applied to evaluate a dierences
among seasons/months (Clarke and Warwick 1994, Clarke
et al. 2008).
Nonmetric multidimensional scaling (NMDS) was used
for analysis of the community composition variability, i.e.
to dene the diatom abundance with relation to sampling
dates. In order to normalize data, diatom abundances ex-
pressed as relative percentages were square root trans-
formed. The Bray Curtis matrix included 285 taxa over 21
samples. In this case, SIMPROF (P < 0.05), SIMPER and
ANOSIM randomization were also used: (i) to dene the
signicantly dierent clusters, (ii) to identify the taxa mak-
ing the greatest contribution to dierences among clusters,
(iii) to test dierences in diatom community over the sam-
pling period.
To investigate the community diversity in the diatom
samples, the Shannon-Wiener Biodiversity Index and the
Margalef index was computed (Kwandrans 2007). As the di-
versity index is not completely eective in describing com-
munity structure, the evenness of benthic diatom assemblag-
es was also computed using both Pielou’s, and Smith and
Wilson's evenness values (Pielou 1966, Smith and Wilson
1996, Beisel et al. 2003).
Canonical analysis of principal coordinates (CAP) was
used to summarize the structure of diatom assemblages over
the months and to determine which physico-chemical pa-
rameters were directly responsible for the variations ob-
served in diatom abundances.
The relationship between the most abundant species
and physico-chemical parameters was analysed by Spear-
man-Rank correlation coecient. Data were transformed
[log(x+1)] to enable the correlation tests among variables
(Cassie 1962). The Kolmogorov-Smirnov test was used for
testing normality of the data distribution. Only signicant
values (*P < 0.05, **P < 0.01, ***P < 0.001) were reported.
Statistical analyses were performed using the PRIMER v6
software (Clarke and Gorley 2006) and Statistica 7.0 (Stat-
Soft, Inc. 2004).
Results
Physico-chemical parameters
Over the study period seawater temperature ranged from
16 °C to 27.3 °C, and salinity ranged from 26.6 to 37.3 (aver-
age 35.5) (Fig. 2A, B). TIN ranged from 0.96 to 10.02 µM and
mostly follow the distribution of NO
3–
. PO
43–
varied from
0.066 µM to 0.578 µM and SiO
44–
from 3.23 to 13.02 µM. The
highest value both PO
43–
and SiO
44–
was recorded on 20
th
of
July. During whole study period, average nutrient concen-
trations were: 3.14 µM NO
3–
, 0.58 μM NO
2–
, 0.97 μM NH
4+
,
0.24 PO
43–
and
7.65 µM SiO
44–
. Oxygen saturation (O
2
/O
2
′)
ranged from 0.57 to 1.39 (average 0.92).
In May-June period the average Chl a was 0.3 µg L
–1
.
During the whole study period, minimum Chl a (0.12 µg
L
–1
) was on 31
st
May and maximum (39 µg L
–1
) on 20
th
July.
Average Chl a in August and September was 2.5 µg L
–1
and
2 µg L
–1
, respectively (Fig. 2D).
The trophic index (TRIX) was lower than 4 (oligotrophic
character of the lake) during the initial sampling period (up
to 24
th
June) and towards the end (from the mid-October).
Lake showed mesotrophic character (4.03–4.76) in the period
the end of June-mid-July, and again at the end of September-
beginning of October. The lake was mostly eutrophic (5.54–
6.02) in the period the end of July–mid-September, and un-
der highly eutrophic conditions (6.44) on the 20
th
July.
Physico-chemical parameters varied signicantly (ANO-
SIM, P < 0.05) among months, seasons (spring, summer, au-
tumn), and between samples collected before the 18
th
June
(Group 1) and afterwards, with exception on 7
th
June (On-
line Suppl. Fig. 3, On-line Suppl. Tabs. 1, 2).
Bacteria
On 20
th
May 2016, heterotrophic bacteria reached values
of 35,479 cells cm
–2
of the glass slide (Fig. 3A). The average
number of bacteria during the study was 42,114 cells cm
–2
with the peak (69,268 cells cm
–2
) at the beginning of June.
During the second part of study a decline in the number of
bacteria was observed.
Diatoms
A peak value of 333,076 cells cm
–2
was observed in Au-
gust. The average abundance over entire study period was
165,946 cells cm
–2
(Fig. 3B).
A total of 285 diatom taxa belonging to 72 genera were
found in samples (Appendix).
Genera with the greatest
number of taxa were:
Mastogloia (36), Nitzschia (29), Na-
vicula (20), Amphora (13), Diploneis (17), Achnanthes (13)
and Cocconeis (12). The most abundant taxa were Cocco-
neis scutellum Ehrenberg var. scutellum and Cocconeis dirup-
ta
W
.
Gregory
var. exella (Janisch and Rabenhorst) Grunow
which occurred in all samples with average relative abun-
dance of 30% and 25%, respectively. The maximum abun-
dance of C. scutellum var. scutellum (90%) was recorded on
7
th
June, while the maximum abundance of C. dirupta var.
exella (65%) was recorded one month later (7
th
July) (see
CAR A, HAFNER D, LJUBIMIR S, DUPČIĆ RADIĆ I, BOBANOVIĆ-ĆOLIĆ S, JASPRICA N
216 ACTA BOT. CROAT. 79 (2), 2020
On-line Suppl. Tab. 4). In total, 48 taxa were found only once
(sporadic) in all samples (Appendix).
The number of taxa per sample ranged from 9 (25
th
May
and 7
th
June 2016) to 52 (11
th
August 2016), with an aver-
age of 25 (Fig. 3C). The Shannon-Wiener Biodiversity Index
varied from 0.74 to 4.51, with an average of 2.93 (Fig. 3D).
Pielou’s species evenness ranged from 0.23 to 0.86 (the aver-
age 0.63) with the minimum occurring in June and the maxi-
mum at the end of September (Fig. 3E). Smith and Wilson
species evenness ranged from 0.06 to 0.45 (the average 0.21)
with the minimum at the end of May and the maximum in
August 2016 (Fig. 3G).
Diatom assemblages differed significantly (NMDS,
ANOSIM, P < 0.05) between the samples collected up to
the middle of July (Group 1) and afterwards (Group 2). Ad-
ditionally, sample from the 12
th
October (Group 3) diered
signicantly from all the others (Fig. 4, On-line Suppl. Tab.
3). Cocconeis scutellum var. scutellum, C. dirupta var. exella,
Opephora mutabilis (Grunow) Sabbe et Wyverman, Navicu-
la salinicola Hustedt, Cocconeis costata W.Gregory, Halam-
phora hyalina (Kützing) Rimet et R.Jahn, Licmophora par-
adoxa (Lyngbye) Agardh, Licmophora abellata (Greville)
C.Agardh, Halamphora coeiformis (C.Agardh) Levkov and
Psammodictyon rudum (Cholnoky) D.G.Mann contributed
the most (cumulatively 70%) to the variance between assem-
blages from Group 1 (10
th
May-13
th
July) and 2 (20
th
July-3
rd
October, SIMPER, Tab. 1). Within Group 1, C. scutellum var.
scutellum and C. dirupta var. exella contributed the most
(cumulatively 95%) to the similarity among diatom assem-
blages from the 10 samples.
Diatom assemblages also diered signicantly (ANO-
SIM, P < 0.05) between the samples collected before the end
of June and samples collected afterwards so the rst group
contained sub-groups A and B with similarity of 40%. Coc-
coneis scutellum var. scutellum, C. dirupta var. exella, L.
abellata, P. rudum, C. costata, Navicula agellifera Hus-
tedt, Nitzschia frustulum (Kützing) Grunow, Cocconeis pseu-
domarginata W.Gregory and Mastogloia cuneata (Meister)
R.Simonsen contributed the most (cumulatively 81%) to the
variance between assemblages from these two su-bgroups.
Diatom assemblages varied signicantly (ANOSIM, P
< 0.05) among months (On-line Suppl. Tabs 3, 4). The pi-
oneer colonization diatom taxa observed after one month
(20
th
May) of exposure of the glass slides were Cocconeis scu-
tellum var. scutellum and C. dirupta var. exella which oc-
cured with average relative abundance of 73% and 15% re-
spectively. These taxa were recorded in all 21 samples. In
May, they contributed the most (cumulatively 90%) to the
similarity among diatom assemblages. Cocconeis scutellum
var. scutellum had the highest average relative abundances
Fig. 2. Distribution of the physico-chemical parameters in Lake
Mrtvo More in 2016. A – temperature, B – salinity, C – oxygen
saturation (O
2
/O
2
′), D – chlorophyll-a concentrations, E – silicate
(SiO
44–
), F – phosphate (PO
43–
), G – nitrate (NO
3–
), H – nitrite
(NO
2–
), I – ammonium (NH
4+
), J – total inorganic nitrogen (TIN),
K – TRIX trophic index.
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 217
in May (72%) and June (58%), while C. dirupta var. exella
dominated (42%) in July. The abundance of C. dirupta var.
exella was 17% and 14% in August and September, respec-
tively. Halamphora hyalina occurred in 50% of the samples
with an average abundance of 6% and maximum of 14% re-
corded on 24
th
August. In 15 samples, L. abellata and H.
coeiformis were observed with average relative abundance
of 3% with the maximum of 13.5% on 7
th
July and 2
nd
Sep-
tember, respectively.
Diatom communities and environmental parameters
Spearman-Rank correlation coecient displays positive
correlation between diatom relative abundance and temper-
ature in case of C. dirupta var. exella and P. rudum (Tab.
2). Psammodictyon rudum also had positive correlation with
salinity. In the case of nutrients, the species C. costata, O.
mutabilis, R. adriaticum and Seminavis sp. correlated with
PO
43–
and NO
3–
. Six diatom taxa (A. kuwaitensis, C. costata,
N. salinicola, Navicula sp., O. mutabilis and Seminavis sp.)
correlated
negatively
with oxygen saturation. Interestingly,
Nitzschia frustulum was not inuenced by any of these 10
environmental variables. In addition, none of diatom taxa
correlated with SiO
44–
(Tab. 2).
Canonical analysis of principle coordinates (CAP)
showed that the samples collected in May and June are more
related with abundance of adnate diatoms, particularly C.
dirupta var. exella and C. scutellum var. scutellum, while
motile forms were better related in the samples from July,
August and September (Fig. 5). Taxa presented in the sam-
ples collected from July to September were associated with
higher seawater temperature and higher nutrient concentra-
tions (e.g. P. rudum, R. adriaticum, T. coarctata). Erect dia-
toms (e. g. L. paradoxa, L. abellata, Fig. 6) appeared in Oc-
tober, when salinity was low.
Fig. 3. Distribution of bacteria and diatom abundances, number of diatom taxa, diversity and evenness indicies in Lake Mrtvo More
in 2016. A – number of bacteria cells cm
–2
, B – number of diatom cells cm
–2
, C – number of diatom taxa, D – Shannon-Wiener diatom
diversity index, E – Pielou’s evenness index, F – Margalef’s diversity index, G – Smith and Wilson's evenness index.
CAR A, HAFNER D, LJUBIMIR S, DUPČIĆ RADIĆ I, BOBANOVIĆ-ĆOLIĆ S, JASPRICA N
218 ACTA BOT. CROAT. 79 (2), 2020
Tab. 1. Diatom taxa with their average abundances contributing to dissimilarities (cumulative = 90%) between diatom assemblages from
Group 1 and Group 2, according to SIMPER analysis. Av.abund. – average abundance, Av.diss. – average dissimilarity, Contrib. – contri-
bution to dierences (%), Cum. – cumulative contribution to dierences (%).
Taxon Group 1 Group 2 Contrib. Cum.
Av.abund. Av.abund. Av.diss. (%) (%)
Cocconeis scutellum var. scutellum 52.53 6.33 23.23 32.17 32.17
Cocconeis dirupta var. exella 29.52 18.96 8.87 12.29 44.46
Opephora mutabilis 073.5 4.85 49.31
Navicula salinicola 0.35 5.87 2.84 3.94 53.24
Cocconeis costata 1.3 6.23 2.58 3.57 56.82
Halamphora hyalina 0.05 5.11 2.54 3.52 60.33
Licmophora paradoxa 0.25 3.86 1.83 2.53 62.87
Licmophora abellata 2.48 1.95 1.69 2.34 65.21
Halamphora coeiformis 1.3 3.64 1.6 2.22 67.43
Psammodictyon rudum 1.13 2.71 1.4 1.95 69.38
Achnanthes kuwaitensis 02.61 1.31 1.81 71.19
Rhabdonema adriaticum 02.53 1.26 1.75 72.94
Tryblionella coarctata 02.39 1.2 1.66 74.59
Fragilaria sp. 2 02.03 1.01 1.4 75.99
Halamphora kolbei 01.95 0.97 1.35 77.34
Amphora sp. 1 1.8 0.53 0.93 1.28 78.63
Seminavis sp. 0.05 1.85 0.91 1.26 79.88
Navicula agellifera 0.62 1.65 0.83 1.15 81.03
Cocconeis pseudomarginata 0.82 2.32 0.82 1.13 82.16
Nitzschia laevis 01.6 0.8 1.11 83.27
Navicula sp.1 0.18 1.49 0.78 1.08 84.35
Navicula directa 0.15 1.25 0.62 0.86 85.21
Halamphora subangularis 01.22 0.61 0.85 86.06
Striatella unipunctata 0.48 1.02 0.6 0.84 86.89
Mastogloia cuneata 1.1 0.2 0.53 0.74 87.63
Diploneis crabro 00.65 0.32 0.45 88.08
Pinnularia sp. 00.65 0.32 0.45 88.53
Grammatophora oceanica 0.58 0.65 0.31 0.43 88.95
Nitzschia frustulum 0.6 00.3 0.42 89.37
Haslea duerrenbergiana 00.57 0.29 0.4 89.77
Pinnularia quadratarea var. cuneata 00.5 0.25 0.35 90.12
Fig. 4. Cluster analysis and non-metric multidimensional scaling (NMDS) ordination on Bray-Curtis similarities matrices from square
root transformed species-relative abundance data of periphytic diatom communities in 21 samples on articial substrate (glass slides) at
depth of 1 m in the marine Lake Mrtvo More in 2016, showing the colonization dynamics of the diatom communities in abundance. For
the ordination analysis all recorded diatom taxa were used. Group average similarity values of clusters with signicant dierences from
CLUSTER analysis were overlaid on the NMDS plot (SIMPROF, P < 0.05). A) Cluster analysis. Red dotted lines showing no signicant
dierence among samples and indicating taxa homogeneous clusters detected by SIMPROF. B) NMDS. Numbers correspond to the same
main clusters detected by SIMPROF. Letters A and B indicate sub-clusters within main clusters. N = 21.
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 219
Fig. 5. Canonical analysis of Principle coordinates (CAP) biplot based on 21 samples in Lake Mrtvo More in 2016 showing: A – diatom
relative abundance (%) data and vectors of the nine physico-chemical parameters (arrows), B – diatom relative abundance (%) data and
vectors of the diatom growth forms (arrows), C – months and vectors of diatom relative abundance (%) data (arrows). S – salinity, T – tem-
perature, O
2
/O
2
′ – oxygen saturation, TIN – total inorganic nitrogen, NO
3-
– nitrate, NO
2-
– nitrite, NH
4+
– ammonium, PO
43-
– phosphate,
SiO
44-
– silicate. A dataset of 13 diatom taxa with frequency of appearance ≥ 17% and average relative abundance ≥ 2% was selected: Acku
– Achnanthes kuwaitensis, Amhy – Halamphora hyalina, Coco – Cocconeis costata, Codi – Cocconeis dirupta var. exella, Cosc – Cocconeis
scutellum var. scutellum, Haco – Halamphora coeiformis, Li – Licmophora abellata, Lipa – Licmophora paradoxa, Nasa – Navicula
salinicola, Opmu – Opephora mutabilis, Psru – Psammodictyon rudum, Rhad – Rhabdonema adriaticum, Trco – Tryblionella coarctata.
Discussion
This study conrms that glass surfaces in a marine en-
vironment are susceptible to biofouling and the biolm is
mostly composed of bacteria and diatoms. Although glass is
a high-energy hydrophilic surface and, as reported by many
studies, diatoms adhere more successfully to hydrophobic
surfaces such as plastic panels, glass has been widely used as
articial substrate for the settlement of diatoms in both ma-
rine and freshwater environments (Nenadović et al. 2015).
In this study, within 30 days of contact a brownish-green
lm of periphyton appeared on the glass substrate surface,
consisting mostly of diatoms dominated by genus Cocconeis.
These results are in agreement with previous observations of
Romagnoli et al. (2007) who reported that a well-developed
community, characterized by the presence of adnate living
forms, is established after 3–5 weeks (the “mature phase”).
Our ndings are also similar to a investigation of Yuanyuan
et al. (2014) where the colonization periods of 10 days or
more might be considered sucient for the mature com-
munities of periphytic diatoms. Additionally, results of this
study conrm that the sampling strategy at 1 m is eective
in detecting the ecological features for bioassessment of ma-
rine ecosystems (Yuanyuan et al. 2014).
The relationships between diatom communities and sub-
strate are mediated by the presence of the bacterial biolm
that rst covers the substrate in succession phases (Totti et
al. 2007). The presence of bacterial biolm on articial sub-
strates may reduce any selective preference displayed by sub-
strates as the presence of organic biolm makes the substrate
CAR A, HAFNER D, LJUBIMIR S, DUPČIĆ RADIĆ I, BOBANOVIĆ-ĆOLIĆ S, JASPRICA N
220 ACTA BOT. CROAT. 79 (2), 2020
Tab. 2. Correlation matrix composed of 10 physico-chemical parameters and 20 diatom taxa with frequency of appearance ≥ 17% and
average relative abundance ≥ 2% (n = 25). Only signicant correlations are reported (*P < 0.05, **P 0.01, ***P < 0.001). T – temperature,
S – salinity, TIN – total inorganic nitrogen, PO
43–
– phosphate, SiO
44–
– silicate, CHL – chlorophyll a concentrations, O
2
/O
2
′ – oxygen
saturation, NO
3–
– nitrate, NO
2–
– nitrite, NH
4+
– ammonium, Acku – Achnanthes kuwaitensis, Amhy – Halamphora hyalina, Amko –
Halamphora kolbei, Coco – Cocconeis costata, Codi – Cocconeis dirupta var. exella, Cosc – Cocconeis scutellum var. scutellum, Haco –
Halamphora coeiformis, Hasu – Halamphora subangularis, Li – Licmophora abellata, Lipa – Licmophora paradoxa, Na – Navicula
agellifera, Nasa – Navicula salinicola, Nasp – Navicula sp., Nifr – Nitzschia frustulum, Nila – Nitzschia laevis, Opmu – Opephora mutabilis,
Psru – Psammodictyon rudum, Rhad – Rhabdonema adriaticum, Sesp – Seminavis sp., Trco – Tryblionella coarctata.
T S TIN PO43– SiO44– CHL O2/O2′NO3–NO2–NH4+
T ........**0.548 .
S ..........
TIN ...*0.687 *0.511 *0.550 **–0.620 ***0.963 ***0.759 .
PO43– . . *0.687 . . **0.686 *–0.706 *0.644 **0.678 .
SiO44– . . *0.511 ...*–0.529 *0.544 . .
CHL . . *0.550 **0.686 ...*0.548 *0.591 .
O2/O2′. . **–0.620 *–0.706 *–0.529 . . **–0.690 . .
NO3–. . ***0.963 *0.643 *0.544 *0.548 **–0.690 .*0.707 .
NO2–**0.548 .***0.759 **0.678 .*0.591 .*0.707 .*0.538
NH4+........*0.538 .
Acku . . *0.478 . . *–0.509 *0.498 . .
Amhy . . *0.557 . . *0.599 .*0.555 . .
Amko . . *0.516 . . . *0.514 . .
Coco . . **0.684 ***0.775 .*0.550 *–0.542 **0.660 . .
Codi *0.532 .........
Cosc .*–0.525 **–0.631 *–0.494 .*–0.587 .**–0.577 . .
Haco ..........
Hasu ..........
Li .........*0.478
Lipa . . *0.523 *0.567 .*0.662 ....
Na ..........
Nasa . . *0.548 . . *0.516 *–0.474 *0.589 . .
Nasp ......*–0.479 ...
Nifr ..........
Nila ..........
Opmu . . **0.672 *0.664 .*0.641 *–0.584 **0.656 . .
Psru **0.601 *0.475 ...*0.648 ....
Rhad . . *0.599 *0.518 .*0.663 .*0.588 *0.512 .
Sesp . . *0.557 ***0.738 .*0.675 *–0.501 *0.528 . .
Trco . . *0.504 . . *0.572 .*0.552 . .
uniform (Korte and Blinn 1983) or may enhance or inhibit
the growth of dierent diatom species (Peterson and Ste-
venson 1989). Most of the research done so far has focused
on the rst hours of the experimental periods. Cviić (1953)
showed that the rapidity of attachment depends on the quan-
tity of organic material in ambient water and that the rst
lm on the slides is formed by bacteria and following them
the most numerous attachments are provided by diatomeae.
Similar results have also been reported and showed that in
a eutrophic environment bacteria rapidly reach maximum
capacity on the slide (Zobell and Allen 1935, Cviić 1953).
The direct microscopy method of counting includes all
visible bacterial cells of which some could not form colonies
on agar plate, or would take a long time to incubate while
spread on the agar plate method, traditionally used in mi-
crobiology, has its limits both in qualitative and quantita-
tive sense because it yields counts of less that 1% of the total
bacterial numbers (Simu et al. 2005). Because of that fact the
number of attached heterotrophic bacteria in our experi-
ments could not be compared with results in the north Adri-
atic Sea counted on agar plate in the initial stages of experi-
ments (Mejdandžić et al. 2015). In addition, Mejdandžić et
al. (2015) investigated colonization of bacteria on plexiglass
(polymer of methyl methacrylate) plates set vertically above
the bottom at a depth of 5 m.
Despite its small dimensions and a level of seasonal an-
thropogenic disturbance, Lake Mrtvo More had a high dia-
tom species richness. In this study, the total number of di-
atom taxa (285) is comparable to some studies of epilithic
diatoms in the south Adriatic (Hafner et al. 2018, Car et al.
2019) but higher than recorded in earlier studies of peri-
phytic diatoms growing on articial substrates in the north
Adriatic (Mejdandžić et al. 2015, Nenadović et al. 2015) or
in a study of surface sediment layer in the Venice lagoon
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 221
Fig. 6. Light micrographs of selected diatom taxa found in Lake Mrtvo More in 2016. A-G – Cocconeis scutellum var. scutellum, H-O – Co-
cconeis costata, P-S – Cocconeis dirupta var. exella, T-V –Licmophora abellata, W, X – Licmophora paradoxa, Y, Z – Rhabdonema adria-
ticum, AA – Halamphora hyalina, AB, AC – Halamphora kolbei, AD – Navicula agellifera, AE – Nitzschia frustulum, AF, AG – Opephora
mutabilis, AH, AI, AJ, AK – Mastogloia cuneata. Scale bar: 10 µm applies to all images.
(Facca and Sfriso 2007). Nevertheless, we believe that at
least partly this can be caused by the dierences in meth-
odology used. Mejdandžić et al. (2015) determined 30 dia-
tom taxa in the periphyton assemblage on plexiglass plates
in a marine environment within 30 days of contact. Apart
from the dierent articial substrate used, the plates were
set vertically rather than horizontally as in our study and the
depth was 5 m. Nenadović et al. (2015) reported 41 diatom
genera periphytic on 11 dierent articial substrates, in-
cluding glass, exposed to a marine environment in a coastal
area of the Central Adriatic Sea for a period of 30 days. The
iron substrate showed the greatest diversity (20 taxa), while
the lowest diatom diversity was recorded on plastic (4 taxa),
concrete (4 taxa) and rubber (2 taxa). While in this study 16
taxa were recorded after a period of one month, Nenadović
et al. (2015) observed 10 diatom taxa associated with glass.
CAR A, HAFNER D, LJUBIMIR S, DUPČIĆ RADIĆ I, BOBANOVIĆ-ĆOLIĆ S, JASPRICA N
222 ACTA BOT. CROAT. 79 (2), 2020
The dierences in the number of diatom taxa detected were
probably due to dierences in methodology used as in the
study of Nenadović et al. (2015) articial substrates were ex-
posed to the marine environment at the much greater depth
of 12 m. Although Nenadović et al. (2015) concluded that
the settling of diatoms on a substrate is greatly inuenced
by substrate characteristics and the preferences of a diatom
communities and diatom species, Totti et al. (2007) found
no signicant dierence in diatom abundance, composi-
tion and biomass values for the three articial substrates
examined (marble, quartzite and slate) and pointed out that
beside the chemical composition of the substrate, its physi-
cal structure should also be considered. The greatest abun-
dance (557,156 cells cm
–2
) observed by Totti et al. (2007)
were higher than those recorded in our study (333,076 cells
cm
–2
). Munda (2005) examined seasonal fouling by diatoms
on vertical concrete plates as articial substrate at dier-
ent depths. In general, our ndings lie within the results
of Munda (2005). Caput Mihalić et al. (2008) also report-
ed 50 diatom taxa on plexiglass plates after 4 weeks (July)
during which the submerged articial substrates exposed
at depths of 0.5, 1, 1.5 and 2. Very similar observations in
the number diatom taxa were found in a study of Hafner et
al. (2018) who identied 264 diatom taxa within 69 genera
in a marine epilithic diatom community of the small semi-
enclosed oligotrophic bay in the Middle Adriatic. In addi-
tion, a comparable number of taxa (310 epilithic taxa, 65
genera) was observed by Car et al. (2019) in a study of epi-
lithic diatom communities from areas of invasive Caulerpa
species in the Adriatic.
In our study considerable uctuation of diatom species
number occurred. It is very likely that the set of algal taxa on
the articial substrate varies to some extent due to predation
(as for example on 31
st
May when a snail was observed eat-
ing periphyton from the glass).
The composition of benthic diatoms throughout the ex-
posure period was relatively consistent with the dominant
taxa belonging to genus Cocconeis whose greatest abundance
was observed after a month of exposure. As succession pro-
gressed, Cocconeis taxa were replaced by other genera of ben-
thic diatoms the abundance of which increased, in particu-
lar, from the end of July. The second to appear on the newly
available articial habitats were motile taxa (e.g. Nitzschia,
Navicula). The co-occurrence and dominance of motile di-
atoms is a further step since biraphid species are capable of
nding the optimum light and nutrient conditions by ac-
tive movement on and through the biolm (Romagnoli et
al. 2007).
The species assemblages present during early colonisa-
tion diered from those at later stages. Assemblages were
found to be quite homogeneous up to the mid-July. An in-
crease in species diversity index from mid-July was noted
and the maximum occurred in August. In general, during
summer diatom diversity increased, mostly due to uctua-
tions of taxa of the genera Cocconeis. Generally, abundance
of diatom cells of genus Cocconeis decreased through the
investigated period.
Similar values of the Shannon diversity index were found
in Lake Mrtvo More as were recorded in a study of the ben-
thic diatom abundance and taxonomic composition in the
Venice lagoon (Facca and Sfriso 2007). Moreover, the sea-
sonal variations of the Shannon diversity index in the Venice
lagoon were not correlated with seawater temperature, al-
though it varied between 6 and 29 °C, but rather with nutri-
ent concentrations. A comparison is, however, dicult due
to the dierent sampling design employed.
Relationships between physico-chemical parameters
and benthic diatoms
Strong relationships between environmental variables
and diatom assemblages were found in Lake Mrtvo More
and shifts in dominance at the species level were recognized.
In the rst stage of the experiment, when generally the nutri-
ent concentrations were low, the lowest number of diatom
taxa was recorded and adnate diatoms appeared. In gener-
al, adnate taxa adhere strongly horizontally to the substrate
by means of their raphe valve and may easily benet from a
nutrient exchange with the substrate due to their adhering
mode through the valve face (Round 1981, Sullivan 1984,
Romagnoli et al. 2014). Diatom species richness of Lake
Mrtvo More was strongly correlated with TIN, constraints
during which C. scutellum var. scutellum remained a com-
mon species in the diatom community. This taxon was the
dominant in the assemblages during the rst months of ex-
periment but its relative abundance declined when seasonal
anthropogenic disturbance started (July). It seems that the
changes in nutrient concentrations induce changes in spe-
cies diversity. This is in agreement with the results of Mar-
cus (1980), who found dierences in diversity between sites
with varying levels of nitrogen concentration during inves-
tigation of periphytic communities using glass slide sub-
strates when recording a greater algal growth downstream
of a dam, which was attributed to nitrogen discharges from
the reservoir. Marcus (1980) suggested that while Cocconies
became dominant at the three downstream sites because of
its greater eciency in obtaining or incorporating limited
nitrogen resources, species other than Cocconies dominated
the diatom communities in which nitrogen concentrations
were enriched apparently because of higher potential growth
rates which could be realized with the elevated nutrient con-
ditions. Cocconeis taxa clearly dier in their response to nu-
trient supply, leading to an altered community composition,
which may be detected only if the species level is considered.
As C. dirupta var. exella was associated with higher tem-
perature values, C. dirupta var. exella remained a common
species and characterized the benthic diatom assemblage of
Mrtvo More during the warmer period of the year.
In this study Nitzschia frustulum was not inuenced
by any of these 10 physico-chemical parameters. This was
showed in previous studies in which N. frustulum has been
described as a highly tolerant diatom taxa which is resistant
to organic pollution and is associated with areas aected by
intensive agricultural and industrial activities (Tornés et al.
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 223
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Conclusion
The study was based on a dataset collected from marine
lake on the eastern Adriatic coast during the warmer period
of the year. In sum, the data revealed the anity of diatoms
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results showed in particular the diatom colonization during
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The present study contributes to the knowledge of the
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the Adriatic and Mediterranean as well. However, data ob-
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which will cover the whole year. These studies must include
other important abiotic (e.g. irradiance) and biotic (e.g. graz-
ing) factors not addressed in the present work. More practi-
cally, the quantication of diatom contribution to the ow
of energy and cycling of material in the lake will be useful
for a rational management of this important resource in the
natural heritage.
Financial support
This research was supported by the Croatian science
foundation (HRZZ, IP-2014-09-2945). The authors thank
Zoran Jurić for his help during sample collection, Steve
Latham (UK) for improving the English, and anonymous
reviewers for valuable suggestions for improving the man-
uscript.
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A.C. and N.J. designed the study. A.C. conducted the
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analyses of diatom samples and determined Chl a uoro-
metrically. I.D.R. analyzed physico-chemical parameters.
S.B.Ć. made bacteriological analyses. All authors revised
the manuscript.
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Appendix
List of 285 marine benthic diatom taxa recorded on articial
substrat (glass) in Lake Mrtvo More from May to October 2016.
Taxa found only once in all number of samples (n = 21) with
relative abundances lower than 1% are indicated with asterisk [*].
The genera at rst mention are listed in boldface.
Achnanthes brevipes C.Agardh
Achnanthes brevipes var. brevipes Agardh
Achnanthes brevipes var. intermedia (Kützing) Cleve
Achnanthes cf. ceramii Hendey
Achnanthes cuneata Grunow
Achnanthes curvirostrum J.Brun
Achnanthes groenlandica (Cleve) Grunow
Achnanthes hyperboreoides A.Witkowski, Metzeltin & Lange-
Bertalot [*]
Achnanthes javanica Grunow
Achnanthes kuwaitensis Hendey
Achnanthes longipes C.Agardh
Achnanthes pseudogroenlandica Hendey
Achnanthes separata Hustedt
Actinocyclus roperi (Brébisson) Grunow ex Van Heurck
Actinocyclus subtilis (W.Gregory) Ralfs [*]
Actinoptychus sp.
Amphicocconeis disculoides (Hustedt) Stefano & Marino
Amphitetras subrotundata Janisch
Amphora abludens R.Simonsen
Amphora bigibba var. interrupta (Grunow) Cleve
Amphora cingulata Cleve
Amphora crassa W.Gregory
Amphora delicatissima Krasske
Amphora exilitata M.H.Gien
Amphora gracilis Ehrenberg
Amphora laevissima W.Gregory
Amphora lineolata Ehrenberg [*]
Amphora lunata Østrup
Amphora proteus W.Gregory [*]
Amphora pseudohyalina Simonsen [*]
Amphora sp.
Ardissonea crystallina (C.Agardh) Grunow
Ardissonea formosa (Hantzsch) Grunow
Ardissonea robusta (Ralfs ex Pritchard) De Notaris
Ardissonea sp. [*]
Asterolampra marylandica Ehrenberg
Aulacoseira granulata (Ehrenberg) Simonsen
Bacillaria paxillifera (O.F.Müller) T.Marsson
Bacillaria socialis (Gregory) Ralfs
Berkeleya sp.
Biddulphia biddulphiana (J.E.Smith) Boyer
Brachysira sp.
Brebissonia lanceolata (C.Agardh) R.K.Mahoney & Reimer
Caloneis bicuneata (Grunow) Boyer
Caloneis liber (W.Smith) Cleve
Caloneis liber var. linearis Cleve [*]
Caloneis sp.
Campylodiscus innominatus R.Ross & Abdin
Catacombas gaillonii (Bory) D.M.Williams & Round
Climacosphenia moniligera Ehrenberg
Cocconeis convexa M.H.Gien
Cocconeis costata var. hexagona Grunow [*]
Cocconeis costata W.Gregory
Cocconeis dirupta var. exella (Janisch & Rabenhorst) Grunow
Cocconeis dirupta W.Gregory
Cocconeis irregularis (P.Schulz) A.Witkowski in Witkowski
Cocconeis peltoides Hustedt
Cocconeis pseudomarginata W.Gregory
Cocconeis schmidtii Heiden
Cocconeis scutellum var. scutellum Ehrenberg
Cocconeis stauroneiformis (W.Smith) H.Okuno [*]
Cocconeis woodii Reyes [*]
Coronia decora (Brébisson) Ruck & Guiry
Craspedostauros indubitabilis (Lange-Bertalot & S.I.Genkal)
E.J.Cox
Diploneis bombus (Ehrenberg) Ehrenberg
Diploneis cf. parca (A.W.F.Schmidt) Boyer
Diploneis chersonensis (Grunow) Cleve
Diploneis crabro (Ehrenberg) Ehrenberg [*]
Diploneis didyma (Ehrenberg) Ehrenberg
Diploneis incurvata var. dubia Hustedt [*]
Diploneis nitescens (W.Gregory) Cleve
Diploneis notabilis (Greville) Cleve
Diploneis smithii (Brébisson) Cleve
Diploneis smithii var. recta Peragallo
Diploneis sp.1 [*]
Diploneis sp.2
Diploneis sp.3
Diploneis splendida Cleve
Diploneis stroemii Hustedt
Diploneis vacillans (A.W.F.Schmidt) Cleve
Diploneis vacillans var. renitens A. Schmidt
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226 ACTA BOT. CROAT. 79 (2), 2020
Entomoneis paludosa (W.Smith) Reimer [*]
Fallacia oriniae (M.Møller) Witkowski
Fallacia forcipata (Greville) Stickle & D.G.Mann
Fallacia ny (Cleve) D.G.Mann
Fallacia pygmaea (Kützing) Stickle & D.G.Mann
Fogedia acuta (Salah) Witkowski, Lange-Bertalot & Metzeltin
Fogedia christensenii A.Witkowski, Metzeltin & Lange-Bertalot
Fogedia nmarchica (Cleve & Grunow) A.Witkowski, Metzeltin
& Lange-Bertalot
Fragilaria capensis Grunow
Fragilaria cf. sopotensis Witkowski & Lange-Bertalot [*]
Fragilaria sp.1
Fragilaria sp.2
Grammatophora angulosa Ehrenberg [*]
Grammatophora angulosa var. islandica [*]
Grammatophora macilenta W.Smith [*]
Grammatophora marina (Lyngbye) Kützing
Grammatophora oceanica Ehrenberg
Grammatophora oceanica var. subtilissima (J.W.Bailey) De Toni
Grammatophora serpentina Ehrenberg
Halamphora acutiuscula (Kützing) Levkov
Halamphora coeiformis (C.Agardh) Levkov
Halamphora costata (W.Smith) Levkov
Halamphora cuneata (Cleve) Levkov
Halamphora exigua (W.Gregory) Levkov
Halamphora hyalina (Kützing) Rimet & R.Jahn
Halamphora kolbei (Aleem) Álvarez-Blanco & S.Blanco
Halamphora subangularis (Hustedt) Levkov
Halamphora subholsatica (Krammer) Levkov [*]
Halamphora turgida (Gregory) Levkov
Hantzschia cf. distinctepunctata Hustedt
Hantzschia cf. marina (Donkin) Grunow
Hantzschia sp.
Hantzschia virgata (Roper) Grunow
Hantzschia virgata var. leptocephala Østrup
Haslea britannica (Hustedt & Aleem) Witkowski, Lange-
Bertalot & Metzeltin
Haslea crucigera (W.Smith) Simonsen
Haslea duerrenbergiana (Hustedt) F.A.S.Sterrenburg
Haslea spicula (Hickie) Bukhtiyarova
Hippodonta caotica Witkowski [*]
Hyalodiscus radiates (O'Meara) Grunow
Hyalosira interrupta (Ehrenberg) J.N.Navarro
Hyalosynedra laevigata (Grunow) D.M.Williams & Round
Licmophora abbreviata C.Agardh
Licmophora abellata (Greville) C.Agardh
Licmophora gracilis (Ehrenberg) Grunow [*]
Licmophora paradoxa (Lyngbye) Agardh
Licmophora pfannkuckae Gien [*]
Licmophora remulus (Grunow) Grunow
Licmophora sp. [*]
Licmophora tincta (C.Agardh) Grunow
Luticola sp.
Mastogloia adriatica Voigt
Mastogloia angulata F.W.Lewis
Mastogloia belaensis Voigt
Mastogloia binotata (Grunow) Cleve
Mastogloia biocellata (Grunow) G.Novarino & A.R.Muftah
Mastogloia borneensis Hustedt
Mastogloia braunii Grunow
Mastogloia cf. armata (Leudiger-Fortmorel) Cleve
Mastogloia corsicana Grunow
Mastogloia crucicula (Grunow) Cleve [*]
Mastogloia crucicula var. alternans Zanon [*]
Mastogloia cuneata (Meister) R.Simonsen
Mastogloia cyclops Voigt
Mastogloia decussata Grunow
Mastogloia emarginata Hustedt
Mastogloia emerginata (cf. ovulum)
Mastogloia erythraea Grunow
Mastogloia exigua F.W.Lewis
Mastogloia exilis Hustedt
Mastogloia fallax Cleve
Mastogloia mbriata (T.Brightwell) Grunow
Mastogloia grunowii A.Schmidt
Mastogloia horvathiana Grunow
Mastogloia ignorata Hustedt
Mastogloia mauritiana Brun
Mastogloia obliqua Hagelstein
Mastogloia ovalis A.Schmidt [*]
Mastogloia ovulum Hustedt
Mastogloia pseudolatecostata T.A.Yohn & R.A.Gibson
Mastogloia pusilla Grunow
Mastogloia regula Hustedt
Mastogloia robusta Hustedt
Mastogloia similis Hustedt
Mastogloia splendida (Gregory) H.Pergallo
Mastogloia varians Hustedt
Mastogloia sp.1 [*]
Nanofrustulum shiloi (J.J.Lee, Reimer & McEnery) Round,
Hallsteinsen & Paasche
Navicula agnita Hustedt
Navicula besarensis Gien
Navicula borneoensis Hustedt
Navicula cincta (Ehrenberg) Ralfs
Navicula dehissa Gien
Navicula directa (W.Smith) Ralfs
Navicula eidrigiana J.R.Carter
Navicula erifuga Lange-Bertalot
Navicula agellifera Hustedt
Navicula frigida Grunow
Navicula gregaria Donkin [*]
Navicula grippii Simonsen
Navicula johanrossii Gien
Navicula palpebralis Brébisson ex W.Smith
Navicula palpebralis var. minor (Gregory) Grunow
Navicula rostellata Kützing
Navicula salinarum var. rostrata (Hustedt) Lange-Bertalot
Navicula salinicola Hustedt
Navicula subagnita Proshkina-Lavrenko
Navicula sp.1
Neohuttonia reichardtii (Grunow) Hustedt
Nitzschia agnewii Choln
Nitzschia bulnheimiana (Rabenhorst) H.L.Smith
Nitzschia capitellata Hustedt, nom. inval.
Nitzschia carnicobarica Desikachary & Prema
Nitzschia compressa (Bailey) Boyer var. compressa
Nitzschia compressa var. elongata (Grunow) Lange-Bertalot
Nitzschia distans W.Gregory
Nitzschia frustulum (Kützing) Grunow
Nitzschia fusiformis Grunow
Nitzschia grossestriata Hustedt
Nitzschia improvisa Simonsen
Nitzschia incurvata var. lorenziana R.Ross
Nitzschia insignis W.Gregory
Nitzschia laevis Frenguelli
Nitzschia lanceolata var. minima Van Heurck
Nitzschia liebethruthii Rabenhorst
Nitzschia longissima (Brébisson) Ralfs [*]
Nitzschia macilenta W.Gregory
Nitzschia marginulata var. didyma Grunow [*]
Nitzschia panduriformis var. continua Grunow
COLONIZATION OF BACTERIA AND DIATOMS IN A MARINE LAKE
ACTA BOT. CROAT. 79 (2), 2020 227
Nitzschia pellucida Grunow
Nitzschia reversa W.Smith
Nitzschia sigma (Kützing) W.Smith
Nitzschia subconstricta Desikachary & Prema [*]
Nitzschia sp.1
Nitzschia sp.2 [*]
Nitzschia tryblionella Hantzsch
Nitzschia valdestriata Aleem & Hustedt [*]
Nitzschia ventricosa Kitton [*]
Opephora burchardtiae Witkowski
Opephora guenter-grassii (Witkowski & Lange-Bertalot) Sabbe
& Vyverman
Opephora mutabilis (Grunow) Sabbe & Wyverman
Opephora pacica (Grunow) Petit [*]
Opephora sp.1 [*]
Parlibellus berkeleyi (Kützing) E.J.Cox [*]
Parlibellus calvus A.Witkowski, Metzeltin & Lange-Bertalot
Parlibellus cf. cruciculoides (C.Brockmann) Witkowski, Lange-
Bertalot & Metzeltin
Parlibellus delognei (Van Heurck) E.J.Cox
Parlibellus rhombicula (Hustedt) Witkowski
Parlibellus sp.
Petrodictyon gemma (Ehrenberg) D.G.Mann
Pinnularia claviculus Schulz
Pinnularia quadratarea var. cuneata Østrup [*]
Pinnularia sp. [*]
Placoneis abellata (F.Meister) Kimura, H.Fukushima & Ts.
Kobayashi [*]
Plagiogramma staurophorum (W.Gregory) Heiberg
Plagiotropis lepidoptera (W.Gregory) Kuntze
Plagiotropis tayrecta Paddock
Planthotrix sp.1
Pleurosigma formosum W.Smith
Pleurosigma sp.1
Pleurosigma sp.2
Podocystis adriatica (Kützing) Ralfs [*]
Protokeelia cholnokyi (M.H.Gien) Round & Basson
Psammodictyon panduriforme (W.Gregory) D.G.Mann
Psammodictyon rudum (Cholnoky) D.G.Mann
Rhabdonema adriaticum Kützing
Rhabdonema arcuatum (Lyngbye) Kützing
Rhoicosphenia abbreviata (C.Agardh) Lange-Bertalot [*]
Rhoicosphenia marina (Kützing) M.Schmidt
Rhoicosphenia sp.
Rhopalodia musculus (Kützing) Otto Müller [*]
Rhopalodia pacica Krammer [*]
Seminavis sp.1
Stauroneis plicata C.Brockmann
Stauroneis undata Hustedt
Stauronella decipiens (Hustedt) Lange-Bertalot [*]
Stauronella sp.1
Staurosira sp.1 [*]
Stephanodiscus hantzschii Grunow
Striatella unipunctata (Lyngbye) C.Agardh
Surirella fastuosa (Ehrenberg) Ehrenberg
Surirella scalaris M.H.Gien [*]
Surirella venusta Østrup
Synedra fulgens (Greville) W.Smith
Synedra laevis Kützing
Synedra tabulata var. obtusa Pantocsek
Tabularia fasciculata (C.Agardh) D.M.Williams & Round
Tabularia investiens (W.Smith) D.M.Williams & Round
Tetramphora decussata (Grunow) Stepanek & Kociolek
Tetramphora sulcata (Brébisson) Stepanek & Kociolek
Toxarium hennedyanum (Gregory) Pelletan
Toxarium undulatum J.W.Bailey
Trachyneis aspera (Ehrenberg) Cleve
Triceratium pentacrinus (Ehrenberg) Wallich
Triceratium reticulum Ehrenberg
Triceratium sp.1
Trigonium arcticum (Brightwell) Cleve
Trigonium formosum (Brightwell) Cleve [*]
Trigonium sp.1
Trigonium sp.2
Tryblionella coarctata (Grunow) D.G.Mann
Tryblionella didyma (Hustedt) D.G.Mann
Tryblionella navicularis (Brébisson) Ralfs
Vikingea promunturi (Gien) Witkowski, Lange-Bertalot &
Metzeltin
