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Discharging untreated ballast waters supports the spread of invasive species. One of the most successful ballast-water mediated biological invasions was a transatlantic transport of the ctenophore Mnemiopsis leidyi to many Eurasian seas, where it has significantly impacted local ecosystems. To prevent its spread to new areas, we studied the survival of different M. leidyi life stages exposed to several eradication techniques. We looked closely into the technical applicability of an onboard thermal treatment by calculating its duration and the required energy to perform it. The duration was considered as a sum of the time to heat ballast tanks by using the engine's waste heat for two types of ships and M. leidyi's eradication. The calculated duration of the proposed treatment allowed us to estimate a minimum travel length undertaken by a specific type of ship to eliminate M. leidyi successfully. The travel length determines the appropriate technique and minimal requirements to eliminate M. leidyi successfully and, thus, can serve as a guideline for a management plan. In conclusion, the proposed onboard treatment would be efficient on smaller ships and minimum distances of 200-300 km depending on the season but not on the short routes where other treatment techniques, e.g. exposure to ultrasonic cavitation or microwave radiation, should be considered.

Sulfur (S), an ubiquitous element in the environment, occurs in different oxidation states from -2 (sulfide, S2-) to +6 (sulfate, SO42−). Reduced forms of S, i.e. reduced sulfur species (RSS: S2-, HS-, S0, SX2-, RSH), are important forms for processes related to S biogeochemistry and environmental quality [1]. Production of marine S species is mainly related to phytoplankton and mcrobial activities, as well as eutrophication phenomena and spreading of hypoxic– anoxic dead zones. A significant fraction of natural S emission occurs in the form of organic S, such as dimethylsulfide (DMS), produced by phytoplankton and zooplankton grazing activities. In different natural water systems, electroanalytical methods have been widely used for the characterization and determination of diferent S species, including dissolved and/or particulate inorganic and organic S forms [2- 5]. Electroanalytical determination of dissolved RSS on the Hg electrode is based on their interaction with the Hg, resulting in the Hg oxidation and the formation of insoluble mercury sulfide (HgS) at potentials more positive than -0.60 (vs . Ag / AgCl). The same process occurs during the interaction of Hg with organic and inorganic RSS that deposit HgS, which during the potential scan toward negative values are reduced, and reduction current at -0.68 V is directly proportional to the concentration of RSS in the sample. RSS that are adsorbed on the Hg surface, or form adsorbable RS– Hg complexes (in the case of DMS, DMDS, cysteine, glutathione) are reduced more positively (around - 0.5 vs. Ag/AgCl) [3-5]. By changing deposition potentials from - 0, 2 V to - 0, 4 V it is possible to make a rough distinction between organic and inorganic RSS that deposit HgS [4, and references therein]. In the presence of organic RSS, by measuring at Ed = -0, 4 V, the HgS reduction peak will decrease or completely disappear. Also, in the adopted electrochemical measurements of the RSS in natural samples, the acidification and purging step by N2 is used to make a distinction between the volatile and non- volatile fraction of the RSS [5]. Unusual phenomena in the sea, such as hypoxia, anoxia or intensive phytoplankton blooms as red tide, can occur as a consequence of environmental, i.e. meteorological conditions, lately highly impacted by climate change. In this paper, cyclic voltammetry (CV) at the Hg electrode was used for characterization of total RSS (RSSTOT) ; non- volatile RSS (RSSNV) and organic S compounds in natural samples collected during the red tide bloom, and in the stratified and holomictic conditions of the unique marine environment on the Adriatic coast (Rogoznica Lake, RL). During stratified conditions in the RL water column, the concentration of RSSTOT (mainly sulfide/S0-like compounds) detected with CV measurements was in the range between 20 nM (oxic layer) to 3 mM (anoxic layer), while concentration of RSSNV (S0- like compounds) ranged between 10 and 100 uM. Additionally, for the first time in the anoxic layer samples differential pulse voltammetry (DPV) was used for determination of polysulfides (SX2)-. The highest concentrations of SX2- (up to 0.1 mM) were determined about 1 m below the oxia/anoxia boundary (~10m) during summer months, when indirectly SX2 formation is proved to be connected by activities of purple phototrophic sulfur bacteria (PSB). In holomictic conditions, when stratification dissapeared, concentrations of both RSSTOT (~100 uM) and RSSNV (~10uM) were decreased and similar throughout the water column. In the same time presence of SX2- and PSB was not detected. Unlike RL samples, in samples of red tide blooms (mainly composed of Noctiluca scintillans), two RSS peaks were detected with CV measurments. First peak, at potential around - 0.5 V, confirms presence of organic S species (RS-Hg type) in the concentration range between 17- 45 nM [3-5]. Second peak at more negative potentials (around -0.68 V), confirms presence of inorganic RSS (sulfide/S0-like compounds) in the concentration range between 7 – 45 nM. Such results support the fact that dinoflagellates among other phytoplankton species contribute the most to the production of sulfur species in the sea [1, 3]. [1] Biogenic sulphur in the environment, E. S. Saltzman and W. J. Cooper (ed.), American Chemical Society, Washington, DC, USA, 1989. [2] I. Ciglenečki, D. Krznarić, G. R. Helz, Environ. Sci. Technol. (2005), 39, 7492. [3] I. Ciglenečki, B. Ćosović, Mar. Chem. (1996), 52, 87. [4] A. Cvitešić Kušan, S. Frka, I. Ciglenečki, Atmosphere (2019), 10, 674 [5] E. Bura-Nakić, G.R. Helz, I. Ciglenečki, B. Ćosović, Geochim. Cosmochim. Acta (2009), 73, 3738.

The Istrian peninsula hosts more than a thousand karstic ponds and a few swamps. Those water bodies are generally artificial or partially modified by humans who relied on them throughout history, mainly for agricultural and livestock activities. Ponds and swamps in the past also represented a problem for human health by favouring mosquito reproduction and malaria diffusion. Thus were massively treated at the beginning of the 20th century with insecticides or artificially connected to the Sea. Nowadays, ponds are often abandoned and prone to regression due to vegetation growth and lack of maintenance. Moreover, they often collect agricultural and urban water runoffs, accumulating microbial and chemical contaminants. Superficial water bodies around the Mediterranean are fundamental for the survival of the surrounding land flora and fauna. In addition, they function as hotspots of aquatic biodiversity that offer the only refuge to various endemic species and are paramount for migratory birds providing an ecosystem network key for preserving the south European biodiversity. This research aimed to examine the habitat characteristics using probe (for temperature, salinity, pH, oxygen saturation) and secchi disk (for depth and water transparency), the microbiological and sanitary conditions and the traces of inorganic contaminants (nutrients such as NH3, NO2-, NO3-, PO43-, SiO4) in the waters of five ponds and a brackish swamp in the southwestern part of the Istrian peninsula. With this investigation, we provided the first data on the status of those fragile and precious environments, which will be the basis to implement their future conservation and sustainable management programs.

Seasonal blooms of invasive ctenophore Mnemiopsis leidyi have become a regular phenomenon in the north-eastern Adriatic (NEA), threatening the pelagic food web and potentially altering the ecosystem dynamics. We hypothesise that ctenophore blooms can trigger substantial changes in carbon compounds and nutrient availability, leading to structural changes in the microbial community. Thus, we analysed the response of the microbial community in situ – inside and outside of M. leidyi swarms, from August- December 2020 in the coastal waters of Rovinj- Rovigno, NEA. Ctenophora abundance was enumerated by visual census. Heterotrophic prokaryotes (HP), cyanobacteria (CB) and heterotrophic nanoflagellates (HNF) were counted by epifluorescence microscopy. Total prokaryotic community composition was determined after eDNA isolation, amplification of 16S rRNA marker gene (V1-V3 region) performed on Illumina MiSeq. Data were analysed using QIIME2 processing pipeline, with taxonomic classification at the order level using SILVA database. Nutrients (orthophosphate, nitrate, nitrite, ammonia, total N and P) were determined spectrophotometrically, dissolved organic carbon (DOC) was measured by standard HTCO method and its surface-active fraction by electrochemistry. Ctenophora in swarms ranged from 20-400 M. leidyi/m3. Microbial abundances, nutrients and carbon content displayed consistently higher concentrations within swarms. Prokaryotic community structure did not show statistically significant differences between the swarms and controls, yet, in most swarms, the shares of Alphaproteobacteria Rhodobacterales increased while Puniceispirillales, Rhodospirillales, SAR11 clade and Gammaproteobacteria SAR86 clade moderately decreased. In conclusion, M. leidyi swarms can alter microhabitat conditions stimulating the growth of HP through increased availability of highly labile and surface-active DOC and CB by the release of ammonia, nitrate and orthophosphate. HNF abundances increase with the higher availability of their prey (HP and CB). The prokaryotic community structure displayed only mild changes, probably due to the episodic nature of the swarm formations impeding a consistent bacterial succession. Partly support of the project MARRES is acknowledged.

Organic carbon (C) is a constituent of many processes in the sea and can be an important indicator of changes in marine system [1]. Due to climate changes, extreme natural weather events (droughts, floods, tropical cyclones, heat waves, intense precipitation i.e. heavy rains, abrupt changes in temperatures, salinity, circulation and mixing, strong winds, Saharan dust transport) are becoming more frequent. Such events lead to unusual phenomena such as mucilaginous algal blooms, red tides, invasive jellyfish blooms, which contribute to eutrophication characterized by anomalous accumulation of organic C in the sea [1-4]. In seawater, organic matter (OM) is a complex of organic compounds (proteins, carbohydrates, lipids, humic and fluvic acids) with different surface active properties [1, 2]. Surface active substances (SAS) can be autochthonously produced mainly through primary and secondary production, release or as secondary metabolites under feeding pressure or allochthonously introduced into the marine system from land and atmosphere. An important property of SAS is that it contains hydrophobic (e.g. fatty acid chains, aromatic rings or hydrocarbons) and hydrophilic functional groups (e.g. -NH2, - COOH, -OH or -SH) that allow the accumulation of SAS at different phase boundaries (e.g. marine surface- atmosphere, particle-aqueous phase, bottom layer- sediment, pycnocline in a stratified water column). Due to such properties, the presence of SAS in water samples can be monitored by adsorption processes at the hydrophobic surface of the mercury (Hg) as a working electrode, by a simple electrochemical method of phase sensitive alternating current (AC) voltammetry [1-3]. Changes of the Hg electrode double layer reflected on the capacitance current are approximately proportional to all (dissolved and particulate) SAS in the solution. The total SAS can be separated into particulate and dissolved fractions by filtering through a 0.45 μm or 0.7 μm filters. SAS content usually can be expressed in the equivalents of the selected model OM substance of Triton-X-100 (eq. T-X- 100) which is considered as a good representative of the most reactive part of the SAS in natural waters [1-3 and references therein]. SAS by normalization to dissolved organic carbon (DOC) content can be expressed as normalized surfactant activity, NSA=[SAS(eq. T-X- 100)/DOC] [2, 3], comparable to NSA of model substances, as representatives for SAS composition of different natural samples. This study will present properties of OM compounds, studied based on their reactivity (hydrophobic properties) during unusual phenomena in the northern Adriatic Sea: a) gelationous zooplankton blooms of the invasive ctenophore Mnemiopsis leidyi (Fig.1.A) [4] and b) red tide, mostly composed of Noctiluca scintillans bloom (Fig.1.B). These events were characterized by remarkable increase of organic C content in otherwise oligotrophic area. OM with surface active properties was recorded both in dissolved (SAS 0, 081-15, 379 mg/L ; DOC 0, 875- 318, 100 mg/L) and particulated fractions (SAS 0, 113-18, 122 mg/L ; POC 1, 666-18, 122 mg/L). The NSA values indicate the presence of more hydrophobic nature of DOC during the gelatinous zooplankton bloom. References [1] I. Ciglenečki, I. Vilibić, J. Dautović, V. Vojvodić, B. Ćosović, P. Zemunik, N. Dunić, H. Mihajlović, Sci. Total Environ. 730 (2020) 139104. [2] Ćosović, B., Vojvodić V., 1998. Electroanalysis, 10(6), 429- 434. [3] I. Ciglenečki, J. Dautović, A. Cvitešić, G. Pletikapić, Croat. Chem. Acta 91(4) (2018) 455- 461. [4] Ciglenečki, I., Paliaga, P., Budiša, A., Čanković, M., Dautović, J., Đakovac, T., Dutour- Sikirić, M., Kraus, R., Kužat, N., Lučić, D., Marić Pfannkuchen, D., Njire, J., Pasarić Z., Supić, N., Under review: Journal of Marine Systems.

The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, C. nodosa successfully adapted to the changes of environmental conditions and prevented H2S accumulation by its re-oxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 by a reduction of light availability which affected photosynthesis of C. nodosa and the oxidation capability of below-ground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of above- and below-ground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation and recovery of the below-ground tissue. Our results indicate that if disturbance of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

The effect of the presence of invasive macroalgae Caulerpa cylindracea Sonder in the seagrass meadow Cymodocea nodosa (Ucria) Ascherson was studied by comparing the dynamics of biological and physicochemical parameters in the tissues of these two macrophytes and in the sediments underlying an invaded meadow (mixed settlement) and a C. cylindracea monospecific settlement. The study was conducted for 15 months, encompassing two summers during 2017 and 2018 (July to September) when maximum C. nodosa growth occurs. During 2017 C. cylindracea biomasses in the mixed settlement (79.5 ± 28.2 to 264.6 ± 65.1 g m–2) were lower than in its monospecific stands (113.4 ± 48.0 to 399.3 ± 56.3 g m–2). In the same period, less reducing conditions in the sediment underlying the mixed settlement were indicated by deeper redox transition depths (RTD: 8–12 mm) than those observed below the C. cylindracea monospecific settlement (RTD: 4–7 mm). In June 2018, C. cylindracea proliferated in both settlements reaching very similar biomasses that were maintained until September 2018 (mixed: 131.5 ± 23.0 to 172.5 ± 16.3 g m–2 ; monospecific: 162.8 ± 32.5 to 178.8 ± 30.0 g m–2). In parallel, a considerable lowering of RTD (5–7 mm) under the mixed settlement indicated the progression of stronger reducing conditions similar to those observed under the monospecific settlement (RTD: 0–7 mm). This alteration was followed by a decrease in C. nodosa below-ground biomass (89.3 ± 16.0 to 140.3 ± 24.3 g m–2), that became considerably lower than in the same period of 2017 (242.3 ± 44.3 to 346.9 ± 32.1 g m–2). At the same time, the above-ground biomass of C. nodosa (72.3 ± 14.8 to 110.3 ± 13.4 g m–2) showed no difference to the summer of 2017 (69.0 ± 15.4 to 116.0 ± 37.4 g m–2). The resulting increase of the above- to below-ground biomass ratio indicated the disruption of the meadow stability. More intense spawning of C. cylindracea in the mixed settlement during the summer 2018 hindered its expected proliferation in October 2018, while the below- ground biomass of C. nodosa increased concomitantly with the deepening of the RTD suggesting a possible recovery of the meadow stability.

The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, the species successfully adapted to the changes in environmental conditions and prevented H2S accumulation by its reoxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 when light availability to the plant was drastically reduced due to increased seawater turbidity that resulted from increased terrigenous input, indicated by a decrease in salinity accompanied with a substantial increase in particulate matter concentration, combined with resuspension of sediment and elevated autotrophic biomass. Light reduction impaired photosynthesis of C. nodosa and the oxidation capability of belowground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of aboveground and belowground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation in the sediment and remainder of the belowground tissue. Our results indicate that if disturbances of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at a maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

Mnemiopsis leidyi distribution, abundance and diet were investigated in the North-eastern Adriatic from summer 2017 to summer 2018. The abundance of zooplankton and anchovies in the areas where M. leidyi was present showed a drastic decrease. The diet of M.leidyi consisted of all the zooplankton taxa found in the surrounding waters with a preference towards larger zooplankton and bivalvia larvae.

Taurine, a sulfur containing organic acid, is produced by marine metazoans and phytoplankton. Omics studies have revealed that proteins involved in taurine uptake and transformation are widespread among marine prokaryotic communities. However, little is known about the production and turnover of taurine in the marine environment. Concentrations of taurine and leucine were measured by High Performance Liquid Chromatography over a seasonal cycle in the coastal northern Adriatic Sea (off Rovinj, Croatia). Concurrently, the bulk uptake and respiration rates of taurine and uptake of leucine by prokaryotes were assessed using radiolabeled substrates. Taurine release rates by copepod communities were also determined. The maxima taurine concentrations (7.9±5.9 nM), assimilation rates (2.7±0.7 nmol L-1 d-1) and release rates by abundant copepods (8.8±12.1 nmol individual-1 d-1) were determined in November, coinciding with a phytoplankton bloom. In contrast, the maximum leucine incorporation rates occurred in summer (5.3±3.7 nmol L-1 d-1). Turnover times ranged from 2h to 7d for leucine and taurine, respectively. Taurine was taken up by a phylogenetically diverse community of prokaryotes, including SAR11 and Thaumarchaeota, as assessed by microautoradiography combined with fluorescence in situ hybridization. However, the shift in the proportion of taurine respired of the total taurine uptake from spring (72.5±4.8 %) to the fall during the phytoplankton bloom (34.5±7.4 %) suggests a response of the prokaryotic community to the availability of this compound. Taken together, our results indicate that taurine is an important nutrient and energy source for microbial communities in nearshore waters.

We investigated the effect of a sewage primary treatment on the bacterial community structure in the waste waters and the impact of their release on the marine environment by combining microbiological, chemical and molecular tools. The study was performed in the town of Rovinj (northeastern Adriatic coast), a typical urban Mediterranean area where untreated or primary treated waters are released in the sea. The results have shown that the primary treatment did not affect substantially the bacterial community structure and did not reduce the concentration of potentially pathogenic bacteria, coprostanol and fecal indicator bacteria. The distribution of the sewage plume in the sea was governed by the vertical stratification and the currents. The rate of bacterial biomass production depended on environmental conditions while bacterial abundance and replication rates were increased in the most polluted waters. In these waters the bacterial community was characterized by the presence of allochthonous bacteria belonging to Epsilonproteobacteria, Firmicutes, Gammaproteobacteria and Bacteroidetes. The latter two taxa were also present in the unpolluted waters but with a different structure that included marine autochthonous members typical for oligotrophic environments (gammaproteobacterial SAR86 clade, OM60 [NOR5] clade and bacteroidetes NS4 and NS5 marine groups, respectively). In addition, the alphaproteobacterial SAR11 clade and the AEGEAN-169 marine group were always abundant only in the unpolluted waters while other groups appeared seasonally. Although the overall impact of sewage waters on the receiving marine environment was limited, a high sanitary risk persisted due to the presence of a relevant proportion of potentially pathogenic bacteria.

We present results of preliminary analysis of physical, chemical and biological data collected in winter 2017, as first step in developing of the ecological model for the northern Adriatic, within frame of the project Ecological response of northern Adriatic to climatic changes and anthropogenic impact (EcoRENA).

A very intense convection episode in the cyclonic South Adriatic Gyre was documented during the winter 18 February 2012 cruise, after an episode of extreme heat loss. The presence of chlorophyll a in addition to Cyanobacteria and chloroplast related pyrotags was detected down to 600 m. Current paths as given by chlorophyll a satellite images on February 25 and drop in salinity (approximately 0.02 in the 0-100 m layer with respect to the previous January cruise) indicated that low salinity and nutrient rich Po River waters might have entered the gyre. That could had happened due to intensified circulatory motions around the Pit during or after the convection event. The inflow of these waters could have favored the very large productivity following the event, later in March. In addition the inflow of low salinity waters from the Po River could have changed dynamic depths of water columns and the rotation intensity around the Pit. The circulation in the area is now being investigated both by ROMS model simulations and by computation of geostrophic currents to verify this new hypothesis.

Given the impact of Mnemiopsis leidyi on pelagic ecosystem and fisheries in the native (coastal temperate western Atlantic) and invaded seas, its introduction in any new area is accompanied with great concern. Following its spread from the Black Sea, where it was introduced via ballast waters, this highly invasive jellyfish has settled in different areas of the southern European seas. In October 2005, it was recorded for the first time also in the northernmost part of the Adriatic. This introduction seemed to be unsuccessful as afterwards M. leidyi was not registered in the Adriatic Sea for more than 10 years. In summer 2016, blooms of M. leidyi were observed in different localities (from lagoon to open water) but all restricted to the northern Adriatic. Here we present data on spatial and temporal distribution of M. leidyi during summer-early autumn 2016 and morphological and biometric data. Preliminary results of egg production experiments using field-collected animals indicated high reproductive potential (136 – 5910 eggs/ind/day) and fast development (< 36 hours to larvae with tentacles) at 22 C and salinity 37.6.

Fekalno onečišćenje važan je ekološki problem priobalnih područja koji utječe na ekosustav i ugrožava ljudsko zdravlje. Akumulacija i postojanost fekalnoga onečišćenja istraženi su u vodenom stupcu i sedimentu tri rovinjske uvale izložene različitim vrstama i količinama otpadnih voda. Razina fekalnog onečišćenja kvantificirana je pomoću bakterijskih indikatora i fekalnih sterola. Raspodjela otpadnih voda oko glavnog kanalizacijskog ispusta u uvali Cuvi ovisila je o udaljenosti od ispusta, volumenu ispuštenih voda, trenutnom strujanju i prisutnosti termokline. Bakterijski indikatori i fekalni steroli bili su značajno korelirani iako se njihov odnos mijenjao sezonski. Fekalna kontaminacija je registrirana u radiusu od 300 m oko ispusta. Sezonske promjene brojnosti heterotrofnih bakterija i produkcije bile su vrlo slične kao i na neonečišćenom području, uz blago povećanje brojnosti i brzine dijeljenja na ispustu. U uvali Valdibora izloženoj utjecaju ispusta tvornice za preradu ribe, unatoč deset puta manjem volumenu u odnosu na ispust u uvali Cuvi razine onečišćenja bile su usporedive. Brojnost heterotrofnih bakterija je bila najveća oko industrijskog ispusta, dok je brzina dijeljenja bakterijskih stanica bila izrazito niska. Granulometrijski sastav površinskih sedimenata (0-5 cm) bio je izmijenjen u odnosu na dublje sedimente (5-10 cm) u krugu od 300 m oko glavnog kanalizacijskog ispusta. U blizini ispusta koprostanol je najvećim dijelom bio vezan za frakciju vrlo sitnog pijeska. Otpadne vode iz tvornice za preradu ribe stvorile su izražene anoksične uvjete u sedimentu koji su pogodovali dijagenetskom procesu nastanka koprostanola. U sedimentima južne luke, izloženim ispuštanju sa brodova i jahti razina fekalnog onečišćenja je bila niska. Fecal contamination represents an important problem for coastal areas that affects the ecosystem and poses a threat to human health. The accumulation and persistence of fecal pollution was analyzed in the sediments and waters along the coast of Rovinj from 3 bays exposed to different types and amounts of sewage effluents. The level of sewage contamination was quantified using fecal indicator bacteria and fecal sterols. The distribution of waste waters around the main sewage outfall in Cuvi bay depended on the distance from the outfall, the volume discharged, the momentary currents and the presence of the thermocline. Fecal indicator bacteria and sterols were strongly correlated but their relation changed from season to season. Fecal contamination was detected in a radius of 300 m from the outfall. Seasonal changes of the abundance and production of heterotrophic bacteria were very similar in the contaminated and uncontaminated areas with a limited increase in the abundance and production close to the outfall. In the bay of Valdibora, influenced by a fish cannery effluent around 10 times smaller than the outfall in Cuvi bay the levels of contamination were comparable. The abundance of heterotrophic bacteria was the largest around the industrial outfall, while the specific rate of replication was very low. The grainsize composition of surface sediment (0-5cm) was altered in comparison to the less contaminated deeper sediment (5-10 cm) in a radius of 300 m around the main sewage outfall. At the sewage disposal site, coprostanol was predominantly associated with very fine sand. The fish cannery effluent, created highly anoxic conditions in the sediment that favored the diagenetic formation of coprostanol. The sediments from the southern harbor, exposed only to boat and yacht effluents displayed very low levels of fecal contamination.

The effect of the substratum type (natural, limestone, or artificial, concrete) on the fatty acid composition of Fucus virsoides in six habitats around the harbours and beaches of the Istrian coast (northern Adriatic Sea) was investigated during the summer, the period of maximum development. All habitats of F. virsoides were regulated by very similar environmental factors and were exposed to moderate anthropogenic influences. F. virsoides growing on artificial substrata was characterised by lower concentrations of fatty acids, lower proportions of fatty acids among total lipids, higher C16:0/18:1 ratios (FA: 6.7±0.6 mg g-1 d.w. ; FA/TL: 22% ; 16:0/18:1: 0.57±0.08) and an overall increase in saturation in comparison to communities growing on natural substrata (FA: 10.2±2.9–12.5±3.4 mg g-1 d.w. ; FA/TL: 30.8–33.7% ; 16:0/18:1: 0.34±0.11– 0.45±0.13). These results likely reflect the less favourable conditions for F. virsoides development on artificial substrates relative to natural substrates. The physiological processes of the algae growing on artificial substrata were more impaired with increasing age (FA: 1.9±0.6 mg g-1 d.w. ; FA/TL: 18.2% ; 16:0/18:1: 0.68±0.08).

The aim of this study was to esteminate number of bacterial community in Boka Kotorska bay by CARD-FISH

Priobalni morski sedimenti predstavljaju završno spremište za razna zagađivala koja mogu znatno utjecati na bentoske zajednice. Kroz resuspenziju ili biološku ugradnju, zagađivala se mogu vratiti u vodeni stupac ili ući u hranidbeni lanac te predstaviti rizik za ljudsko zdravlje. Analizom kvalitativnog i kvantitativnog sastava bentoskih organizama i bakterija kao indikatora izmjerena je razina fekalnog onečišćenja i njen utjecaj na morsko dno u blizini glavnog ispusta grada Rovinja. Izmjerene koncentracije fekalnih koliforma i streptokoka pokazale su da je morsko dno na udaljenosti do 150m jako zagađeno i da onečišćenje na većim udaljenostima opada. Utvrđeno je da se zagađenje najviše širi u sjeverozapadnom smjeru zbog morskih struja i morfologije dna. Trend kretanja onečišćenja sličan je u svim smjerovima osim u sjeveroistočnom gdje zbog smanjenja dubine dolazi do akumulacije fekalnog materijala na 50m od ispusta i opadanja širenja na većoj udaljenosti. Brojnost, raznolikost i distribucija mnogočetinaša, meiofaune, školjkaša i foraminifera pokazale su da je utjecaj ispusta značajan. Blizu ispusta i u smjeru širenja zagađenja prevladavaju oportunističke vrste. Udaljavanjem od izvora zagađenja povećava se raznolikost vrsta. U sjeveroistočnom pravcu na udaljenostima većim od 50m uočena je velika raznolikost svih navedenih organizama, što ukazuje na povoljne uvjete za njihov rast. Prirodni čimbenici kao što su tip sedimenta i organska tvar također su utjecali na distribuciju bentoskih zajednica. Postaje koje su imale veći udio krupnijeg sedimenta s manjim udjelom sitnozrnatih čestica silta i gline odlikovale su se raznolikošću organizama. Preliminarni rezultati ukazuju da na sastav i strukturu bentoskih organizama utječu prirodni i antropogeni čimbenici.

Ispuštanje kanalizacije u more značajno utječe na kvalitetu voda u širem priobalnom pojasu. Otpadne vode, bogate su organskim i anorganskim tvarima i uzrokuju promjene u veličini, strukturi, proizvodnji i funkciji autotrofne i heterotrofne mikrobne zajednice. Neobrađene ili primarno obrađene otpadne vode, kakva je većina na našoj obali, obiluju visokim udjelima alohtonih bakterija među kojima prevladavaju patogeni. Unosom patogena u morsku okolinu, povećava se mogućnost širenja različitih infekcija i bolesti kod ljudi direktno kroz morsku vodu ili indirektno kroz prehrambeni lanac. U ovom radu analizirana je jednogodišnja sezonska dinamika fekalnog zagađenja i njen utjecaj na mikrobne zajednice vodenog stupca na području kanalizacijskog ispusta grada Rovinja. Za određivanje zagađenosti mora korišteni su bakterijski indikatori fekalni koliformi i fekalni streptokoki. Oni su pokazali da je razina i distribucija fekalnog zagađenja jako različita u zimskom i u ljetnom razdoblju. Tijekom ljeta zbog stabilnog stratificiranog vodenog stupca onečišćenje ostaje potisnuto u pridnenom sloju, te se proteže do udaljenosti od 300 m od ispusta. U zimskom razdoblju vodeni stupac je vertikalno izmiješan te omogućuje širenje fekalnog zagađenja prema površini. Zimi je zagađenje koncentrirano na površini, a pri dnu je minimalno, te se proteže do udaljenosti od 150m od ispusta. Najveće razlike u distribuciji autohtone mikrobne zajednice utvrđene su između samog ispusta i 50 m udaljenosti i to za pikoeukariote i heteotrofne bakterije, dok su populacije Synechococcusa pokazale homogen raspored čitavim profilom. Maksimalna abundancija heterotrofnih bakterija izmjerena je kod samog ispusta. Udaljavanjem od ispusta njihova distribucija je slijedila ljetni površinski maksimum čitavim profilom (ukazujući na korištenje drugačijih izvora organske tvari). Brojnost i distribucija autohtone mikrobne zajednice pokazuje da je utjecaj otpadnih voda vidljiv samo na ispustu, te se bitno smanjuje povećanjem udaljenosti.

Priobalni morski sedimenti predstavljaju završno spremište za razna zagađivala koja mogu znatno utjecati na bentoske zajednice. Kroz resuspenziju ili biološku ugradnju, zagađivala se mogu vratiti u vodeni stupac ili ući u hranidbeni lanac te predstaviti rizik za ljudsko zdravlje. Analizom kvalitativnog i kvantitativnog sastava bentoskih organizama i bakterija kao indikatora izmjerena je razina fekalnog onečišćenja i njen utjecaj na morsko dno u blizini glavnog ispusta grada Rovinja. Preliminarni podaci ukazuju da je morsko dno u blizini ispusta jako onečišćeno te da opada s udaljenošću od ispusta. Utvrđeno je da se onečišćenje najviše širi u sjeverozapadnom smjeru zbog morskih struja i morfologije dna, dok na 50 m u smjeru sjeveroistoka zbog smanjenja dubine dolazi do zamjetne akumulacije i zadržavanja fekalnog materijala. Brojnost, raznolikost i distribucija mnogočetinaša, meiofaune, školjkaša i foraminifera također su pokazale da je utjecaj ispusta značajan. Blizu ispusta i u smjeru širenja onečišćenja prevladavaju oportunističke vrste. Udaljavanjem od izvora onečišćenja povećava se raznolikost vrsta. U sjeveroistočnom pravcu na udaljenostima većim od 50 m uočena je velika raznolikost svih navedenih organizama, što ukazuje na povoljne uvjete za njihov rast. Prirodni čimbenici kao što su tip sedimenta i organska tvar također su utjecali na distribuciju bentoskih zajednica. Postaje koje su imale veći udio krupnijeg sedimenta s manjim udjelom sitnozrnatih čestica silta i gline odlikovale su se raznolikošću organizama. Dosadašnji rezultati pokazuju da na sastav i strukturu bentoskih organizama utječu prirodni i antropogeni čimbenici. Očekujemo da će preostale analize upotpuniti i potvrditi navedene rezultate.

Kroz godinu dana obavljena je studija stanja okoliša u Pješčanoj uvali, naselju u blizini Pule u južnoj Istri. Pješčana uvala ima problem sa otpadnim vodama zbog naglog rasta i razvoja naselja koje je doveo do diskutabilnih zahvata u gradnji poput spajanja odvoda kišnice i kanalizacije u određenim kućama. Tokom jakih kiša je pritom moguće da se prihvatni kapacitet sustava odvodnje prepuni te da dođe do izljeva mješavine otpadnih i oborinskih voda u uvalu. Stoga su istraženi hidrografski i mikrobiološki parametri uvale. Od hidrografskih parametara istraženi su temperatura, salinitet, pH i saturacija vode kisikom. Od mikrobioloških parametara istražene su koncentracije fekalnih indikatora vrste Escherichia coli, fekalnih streptokoka i ukupnih koliforma te morsku autohtonu mikrobiološku zajednicu gdje su izmjerene koncentracije autotrofnih cijanobakterija i heterotrofnih prokariota i nanoflagelata. Istraživanja su pokazala sezonske oscilacije u sanitarnom stanju uvale. Moguće je pretpostaviti da je uzrok neuravnoteženi kišni režim na području i neadekvatna infrastruktura za prihvat i odvod oborinskih voda. Najviše povišene koncentracije fekalnih indikatora su registrirane za jesensko uzorkovanje, kada su oborine u južnoj Istri najobilnije. Osim za jesen također je za zimu i ljeto bila barem jedna postaja sa povišenim koncentracijama. Plaže za kupanje imale su najniže vrijednosti FI što znači da kupači nisu pri opasnosti. Morska mikrobiološka zajednica imala je povećanu heterotrofnu komponentu, koja je imala raspored u uvali poput fekalnih indikatora. Zaključak je da su se heterotrofi hranili organskom tvari koja je ušla u uvalu s fekalnim indikatorima. Međutim, autotrofna komponenta je pak pokazivala snižene koncentracije, vrlo vjerojatno jer autotrofnim organizmima smetaju promjene hidrografskih uvjeta uzrokovane unosom mješavine voda. Over the course of a year, a study of the state of the environment was carried out in Pješčana uvala, a settlement near Pula in southern Istria. Pješčana uvala has a problem with wastewater due to the rapid growth and development of the settlement, which has led to debatable interventions in construction, such as the connection of rainwater drains and sewage in certain houses. During heavy rains, it is possible for the reception capacity of the drainage system to overflow and for a mixture of waste and rainwater to flow into the bay. Therefore, the hydrographic and microbiological parameters of the bay were investigated. Of the hydrographic parameters, temperature, salinity, pH and water saturation with oxygen were investigated. Among the microbiological parameters, the concentrations of fecal indicators of Escherichia coli, fecal streptococci and total coliforms and marine autochthonous microbiological indicators were investigated, where the concentrations of autotrophic cyanobacteria and heterotrophic prokaryotes and nanoflagellates were measured. Research has shown seasonal oscillations in the sanitary condition of the bay. It is possible to assume that the cause is an unbalanced rain regime in the area and inadequate infrastructure for receiving and draining rainwater. The highest concentrations of fecal indicators were registered for autumn sampling, when the precipitation in southern Istria is the most abundant. Except for autumn, there was also at least one station with elevated concentrations for winter and summer. The bathing beaches had the lowest FI values, which means that bathers are not at risk. The marine microbiological community had an increased heterotrophic component, which was distributed in the bay like faecal indicators. It can be concluded that heterotrophs fed on organic matter that entered the value with fecal indicators. However, the autotrophic component showed reduced concentrations, most likely because autotrophic organisms interfere with the changes in hydrographic conditions caused by the intake of the water mixture.