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Surface analytical methods are applied to examine the environmental status of seawaters. The present overview emphasizes advantages of combining surface analytical methods, applied to a hazardous situation in the Adriatic Sea, such as monitoring of the first aggregation phases of dissolved organic matter in order to potentially predict the massive mucilage formation and testing of oil spill cleanup. Such an approach, based on fast and direct characterization of organic matter and its high-resolution visualization, sets a continuous-scale description of organic matter from microto nanometre scales. Electrochemical method of chronoamperometry at the dropping mercury electrode meets the requirements for monitoring purposes due to the simple and fast analysis of a large number of natural seawater samples enabling simultaneous differentiation of organic constituents. In contrast, atomic force microscopy allows direct visualization of biotic and abiotic particles and provides an insight into structural organization of marine organic matter at micro- and nanometre scales. In the future, merging data at different spatial scales, taking into account experimental input on micrometre scale, observations on metre scale and modelling on kilometre scale, will be important for developing sophisticated technological platforms for knowledge transfer, reports and maps applicable for the marine environmental protection and management of the coastal area, especially for tourism, fishery and cruiser trafficking. [ABSTRACT FROM AUTHOR]

The north-western part of the northern Adriatic (NA) exhibits eutrophic to mesotrophic characteristics with recurrent algal blooms and quite unpredictable mucilage events. To contribute to the understanding of the mucilage events in the NA a machine learning algorithm for induction of regression trees was applied on a long-term data-set comprising physical, chemical and biological parameters, measured at six stations on the profile from the Po River delta (Italy) to Rovinj (Croatia). A model describing the connection between the TIN/PO4 ratio, considered as a necessary factor and sometimes even a trigger for mucilage events, and the environmental conditions in NA, was elaborated. The model for TIN/PO4 ratio confirmed the assumption that the mucilage events are connected with this ratio, e.g. mucilage events coincides with its high values. This finding indicates that at certain levels of phosphorus limitation (from TIN/PO4 ratio) mucilage event frequency increases. The model also reveals that salinity and temperature are responsible for the changes of the TIN/PO4 ratio and gives an insight on their threshold values which lead to high values of this ratio, further related to mucilage events. [ABSTRACT FROM AUTHOR]

We analysed the 1997 summer mucilage event in the northern Adriatic and showed that macroaggregates were formed in the upper layers of the water column in central parts of large gyres and were dispersed by currents which seem to be of geostrophic origin. Beside Cylindrotheca closterium , an already established regular opportunistic species of the mucilage phenomenon, originating from the sediment, we detected another benthic species, Thalassionema nitzschioides , of sporadic character. Both were present in scarce amounts in the water column at the time of sampling first macroaggregates, but reached high abundances after/close to the mucilage event ending. The first, and the most intense surface heat loss episode, on 18 July (heat loss of around 240 W m −2 , during episode of NW wind), in time of first macroaggregates formation, introduced C. closterium from sediment into the water column and enabled dispersion of T. nitzschioides, present in central region both in water and in first macroaggregate samples, eastwards and westwards. The later, less intense surface heat loss episodes, between end of July and mid of August (30–160 W m −2 , induced mostly by NE winds) were efficient (1) in tearing already formed macroaggregates, enabling in that way release of opportunistic species from a macroaggregate into the surrounding water column, and (2) in transporting lower salinity waters of specific species populations with macroaggregates form west to east, extending the event to large area. We hypothesise, first, that summer surface heat loss episodes play a role in sustaining mucilage events by introduction of C. closterium from the sediment and/or decaying macroaggregates in the water column. Second, that geostrophic currents are important in spreading of various types of aggregates, including marine snow, over the wider marine areas. [ABSTRACT FROM AUTHOR]

In the northern Adriatic Sea, Mediterranean Sea, the mucilage phenomenon is usually related to the aggregation of extracellular organic matter of phytoplanktonic origin under special seasonal and trophic conditions. Environmental factors, such as temperature, salinity, nitrogen, phosphorus and N/P ratio as well as polysaccharide and monosaccharide levels in the presence and absence of mucilage were investigated in the northern Adriatic Sea. Variations in temperature and salinity during spring in years characterised by mucilage events have been recognised having an important role in preparing a favourable physical environment where mucilage formation could take place. Since the DIN/TP ratio increased markedly during the spring months (March–April) in 2002, 2003 and 2004, preceding the early summer mucilage outbreaks, it appeared that the DIN/TP ratio may be a more robust predictor than the DIN/DIP ratio, which, although more commonly used, exhibited a discontinuous trend. The contents of total carbohydrates, including monosaccharides and polysaccharides, in seawater also varied according to the presence or absence of mucilage, with an increase of polysaccharide levels during the late spring or early summer in the period of the mucilage appearance. The role of carbohydrates in the macro-aggregate formation was also investigated. [ABSTRACT FROM PUBLISHER]

The DYFAMED sediment trap station in the Ligurian Sea (NW Mediterranean) has been active since 1986 and today comprises the longest time-series of downward particle flux in the Mediterranean Sea. As such, it provides valuable information on the interannual variability of the particle flux, and also documents possible recent changes in the NW Mediterranean pelagic ecosystems. We report an unprecedented episode of downward flux of mucilaginous material at the DYFAMED station during summer 2002 in association with singular hydrometeorological conditions. The rain of mucilaginous aggregates clogged a PPS5 sediment trap at 260 m depth and was also clearly detected at 1080 m depth. The possible factors governing the development and sinking of the mucilaginous material are discussed. A very sharp increase of sea surface temperature during June and the presence of freshened waters in the surface the following month resulted in a stronger than usual stratification of the upper water column throughout the summer season. We suggest that the steepness of the vertical density gradient was responsible for the unusual accumulation of mucous aggregates. Additionally, a diatom bloom took place during the nutrient-depleted conditions typical of summer, a factor which may have contributed to feed the pycnocline with transparent exopolymer substances. A storm occurring in the beginning of August relaxed the stratification and promoted the deposition of the mucilaginous aggregates accumulated in the upper water column during the preceding months. Important similarities of ambient conditions preceding the apparition of mucilaginous material in our open-sea site and those reported in the Adriatic Sea during major mucilage events, suggest that general climatic conditions, rather than local factors, drive the occurrence of major accumulations of mucilaginous material in the water column at both sub-basins of the Mediterranean Sea. In this regard, the strength of the air temperature increase during the onset of the stratified season is proposed as a major controlling factor. [ABSTRACT FROM AUTHOR]

Total dissolved carbohydrates and their monosaccharide and polysaccharide fractions were studied at a fixed sampling point in the northern Adriatic Sea off Pesaro, Italy, in 2002, 2003, and 2004 which were characterized by the presence of macroaggregates, and in 2001 and 2005 when the macroaggregates were absent. During the presence of macroaggregates in 2004, the study was extended to the southern part of the Gulf of Trieste, Slovenia. In parallel, phytoplankton biomass determined from chlorophyll a concentration, and nitrogen and phosphorus nutrients were tracked. The concentrations of total dissolved carbohydrates and, above all, dissolved polysaccharides were higher in late spring and early summer before and during the mucilage appearance. Conversely, the concentrations of dissolved monosaccharides remained nearly constant throughout the study period. In addition to higher polysaccharide concentration, other hydrological, chemical and biological factors seem also important for macroaggregate formation in the northern Adriatic Sea. Among them, the DIN/PO3-4 ratios, regularly increasing in spring due to phytoplankton use of nitrate and phosphate, could be indicative of macroaggregates appearance since they were lower in 2001 and 2005 while during the presence of mucilage in 2002, 2003 and 2004 they markedly increased. [ABSTRACT FROM AUTHOR]

Abstract: Carbon and nitrogen stable isotope ratios of particulate organic matter (POM) were studied approximately weekly during spring and summer 2003 and 2004 in the Gulf of Trieste (northern Adriatic Sea) in order to track the temporal variations and differences between two years. In parallel, particulate organic carbon (POC) and particulate nitrogen (PN), phytoplankton biomass (chlorophyll a), and N and P nutrients were monitored. All studied parameters, especially N and P nutrients and chlorophyll a, showed higher concentrations and larger variability in spring 2004. As a consequence the macroaggregates were produced in late spring 2004. The C and N isotope composition of POM was not directly linked to phytoplankton biomass dynamics. The δ 13CPOC values covaried with temperature. In 2004, δ 13CPOC variations followed the δ 15NPN values as well as the δ 13CDIC values which were probably more dependent on the photosynthetic use of 12C. Variations in δ 15NPOM values were most probably the consequence of variations in N nutrient sources used in phytoplankton assimilation. The significant correlation between δ 15NPN values and nitrate concentrations in 2004 implies intense nitrate assimilation in the presence of higher nitrate concentration. This suggests nitrate as the key nutrient in the »new primary production«, later producing macroaggregates with a mean δ 13C and δ 15N values of −19‰ and 5‰, respectively. A low fractionation factor ε, <1‰, lower than that reported in other marine and lacustrine systems, was found probably to be a consequence of distinct phytoplankton species, i.e. several classes of autotrophic nanoflagellates, and specific growth conditions present in the Gulf of Trieste. The tentative use of C isotope composition of POM revealed a higher contribution of allochthonous organic matter in 2004 compared to 2003 due to higher riverine inflow. [Copyright &y& Elsevier]

Abstract: Dissolved and particulate carbohydrates (DTCHO and PTCHO) as well as surface-active substances concentrations and relative acidities (SAST and Acr) were studied in the northern Adriatic Sea during the period between 1998 and 2005 with the aim to investigate their temporal and spatial dynamics in the basin and possible links with the mucilage events with help of comprehensive statistical data analysis. The investigated time period encompassed 3 years characterized by intensive appearance of mucilage aggregates (mucilage years) and 3 years without this phenomenon (non-mucilage years). In order to explore possible regularities in the distribution and covariation of investigated parameters, univariate and multivariate analyses of variance (MANOVA) were performed, considering effects of different parameters, including water column depth, geographic location, season, individual year, and mucilage appearance. The investigated organic matter parameters showed a significant complexity of their temporal (seasonal, interannual) and spatial (vertical and horizontal) distribution patterns. Although some characteristics of the distribution patterns, such as seasonality and differences between surface (0.5m) and deeper layers, were already described in the literature, this work provides the first rigorous statistical analysis performed on a larger data set, allowing quantitative assessment of the observed differences. It was shown that mucilage years in the northern Adriatic were characterized by different patterns of the investigated four organic matter parameters, compared to those of the non-mucilage years. Moreover, it was shown that carbohydrates substantially contribute to the overall surfactant activity of the present organic matter, especially in the surface layer of the most productive western part of the basin, indicating new production, triggered by river-born nutrients, as the predominant source. To the best of our knowledge, this is the first evidence for a possible coupling between CHO and surfactant-activity in environmentally relevant conditions. [Copyright &y& Elsevier]

Abstract: The mucilage phenomenon, a sporadic but massive accumulation of gelatinous material, can cause serious damage to the tourism and fishing industries along the Adriatic coast. Mucilage is presently thought to be the result of the aggregation of dissolved organic matter (DOM) into particulate organic matter (POM). Three principal classes of compounds have been identified in organic matter by spectrometric determination: carbohydrates, proteins and lipids. Carbohydrates are suspected to play a role in the first steps of DOM aggregation. Despite its importance in understanding the processes leading to mucilage formation, our present knowledge of the composition of the mucilage carbohydrate fraction is incomplete. Due to its high sensitivity and specificity, liquid chromatography coupled with electrospray-ionization tandem mass spectrometry (LC–ESIMS/MS) is gaining an increasing importance as a powerful technique for carbohydrate purification and characterization in complex samples. In this work, LC–ESIMS/MS is proposed as a useful method for the investigation of the oligosaccharide content in mucilage samples. The approach was applied using 3–7 unit maltooligosaccharides as reference compounds. The composition of the investigated mucilage sample was further investigated combining LC–ESIMS/MS with classic approaches, such as spectroscopic techniques and liquid chromatography coupled with the refractory index LC–RI. [Copyright &y& Elsevier]

Meteorological and oceanographic conditions in the Northern Adriatic Sea in a year notable for massive mucilage formation (2004) were compared with those in years where this phenomenon did not occur (2003, 2005 and 2006) to suggest possible links. The months preceding the mucilage event in 2004 were considered the ‘incubation period’ and were characterized by a strong freshet in May which increased the water column stability. Winter cooling and scarcity of freshwater inputs from the Po River triggered the dense water formation and intrusion in the northern basin. Weak southeasterly winds and an increase in surface seawater temperatures contributed to maintain and reinforce the water column stability, and at the same time an intense diatom spring bloom created the conditions for accumulation of organic matter. The interplay of climatological forcings and biological processes caused temporal variations of dissolved organic carbon (DOC) and particulate organic carbon (POC) in the basin, with POC playing an important role in the aggregation process, as suggested by its increase relative to DOC before massive mucilage formation. We therefore suggest that high POC/total particulate nitrogen ratios in the suspended particulate organic fraction, a steep increase of POC/Chlorphyll a, and the decreased DOC/POC ratios represent ‘early warning’ signals of the main processes that lead to mucilage events in the Northern Adriatic Sea. [ABSTRACT FROM AUTHOR]

Abstract: Recurrent occurrences of visible mucilage “clouds” that cover areas up to several hundred kilometres with vertical dimensions of 20–30m have been recorded in the stratified water column in the northern Adriatic. In the past this was described as “mare sporco” phenomenon. Past studies of the phenomenon indicated that phytoplankton is an important component of mucilage. Our research revealed the composition of phytoplankton assemblages in different types of mucilaginous aggregates collected during the summers of 1997 and 2000 using pigment biomarkers (HPLC). Phytoplankton biomass in the mucilage samples was very high, ranging from 7.9μgg−1 to 390.8μgg−1 of chlorophyll a per unit of dry mass of mucilage. The phytoplankton community in the early, loose stage of mucilaginous aggregates was heterogeneous, as indicated by the diversity of detected pigments. The number of phytoplankton groups decreased as the aggregates aged and diatoms increased in relative biomass (up to 92.7%). Phytoplankton biomass in seawater was similar in years with and without mucilage; however, significantly higher contributions to the total biomass of 19′-hexanoyloxyfucoxanthin-containing phytoplankton (prymnesiophytes) were found in the upper 10m in spring of the “mucilaginous years” (1997 and 2000) followed by prevalence of diatoms in summer. The F p pigment index used to assess seawater trophic conditions reached lower values in April–May in mucilaginous years (1997 and 2000) compared to non-mucilaginous years (1998 and 1999). We conclude that the role of prymnesiophytes and other small flagellates is crucial for the initial phases of mucilage appearance. Aggregates represent a favourable environment for the secondary development of opportunistic diatoms that foster mucilage formation. [Copyright &y& Elsevier]

The massive accumulation of organic matter, which periodically occurs in the northern Adriatic Sea, and in other locations worldwide, is presently thought to be the results of the aggregation of dissolved organic matter (DOM) into particulate organic matter (POM). This phenomenon is the result of human activities and propitious weather conditions. Although many aspects of the phenomenon are well understood, the trigger mechanisms leading to mucilage formation have not been clarified yet, probably as a consequence of inadequate analytical approaches. In this context, the recent advancements in LC-MS interfacing might contribute in clarifying the mechanism of mucilage formation. In the present paper, hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry (HILC-ESI-MS/MS) is proposed as an innovative method for the investigation of underivatized oligosaccharides in mucilage samples. Recent findings suggest that the significant presence of these compounds in seawater can play an important role in the initial steps of the agglomeration processes forming gelatinous material. Our results reveal the presence of several maltodextrines in the water-soluble fraction of mucilage macroaggregates, collected in various locations of the northern Adriatic Sea. In our knowledge, the proposed method is the first application of LC-MS in the investigation of marine mucilage. [Copyright &y& Elsevier]

During nearly every summer of the last 15 years, massive mucilage aggregations have formed in the water column of the northern Adriatic. The phenomenon also occurred during the summer of 2004, lasting approximately from the middle of June to the end of July. After approximately 20 days of mucilage impact (coverage of the rocky bottom from 40% to 90%), the effects on selected macrobenthic species were assessed at depths of 5–7m. The responses to the mucilage impact were species dependent. Smothering by mucilage caused partial necrosis of the sponge Verongia aerophoba: from 7% to 56% of the colony surface was deteriorated. In contrast, the impact was lethal for the mollusc Arca noae: from 5% to 45% of the molluscs died. Usually, no deleterious effects were ascertained on perennial parts of the thalli (axes) of macroalgae of the genus Cystoseira. However, primary branches showed signs of necrosis, and Cystoseira compressa was more sensitive compared to Cystoseira corniculata and Cystoseira barbata. Apparently, this does not profoundly affect Cystoseira populations, which have been in a phase of expansion along the shallow Istrian rocky coast over the last 15 years. [Copyright &y& Elsevier]

In the Adriatic Sea, the correlation between mucilage phenomena and the presence of Gonyaulax fragilis (Schütt) Kofoid (Dinophyta) has been recently demonstrated. The application of PCR-based methods and the development of species-specific molecular probes might represent powerful technologies for rapid and specific monitoring of microalgal species in seawater samples. Here, we report sequencing of the small subunit (SSU) ribosomal RNA gene (18S rDNA) of G. fragilis and its comparative analysis within the Dinophyta. Total DNAs were extracted and amplified from cultured cells of G. fragilis, which were isolated from natural phytoplanktonic association in the northern Adriatic Sea. Total 18S rDNA gene was amplified using 16S1N and 16S2N primers and sequenced using ad hoc designed internal primers. The primers amplified a product of expected size (length 1700/1800 bp). The phylogenetic analysis carried out by comparing G. fragilis sequence to homologous sequences of Lingulodinium polyedrum (Stein) Dodge, Gonyaulax spinifera (Claparède et Lachmann) Diesing, Protoceratium reticulatum (Claparède et Lachmann) Bütschli revealed a great nucleotide divergence of G. fragilis SSU sequence. Therefore, the SSU sequence could be used as species-specific marker for the identification of this mucilage producer microalga. In addition, such sequence could be used as target to design oligonucleotide probes for the construction of DNA microchips as diagnostic tool for the routine monitoring of harmful algae in seawater. [ABSTRACT FROM AUTHOR]

The chemical composition of mucilage aggregates found during summer 2000, 2001 and 2002 in the North Adriatic Sea depends on the nature of the organic matter during aggregation, on the environmental conditions of the site of formation and on the transformations during ageing. The mucilages were composed of organic matter, together with a significant inorganic fraction. Elemental analysis revealed 12.5–32.2% of organic carbon, 0–7.3% of inorganic carbon and 1.0–3.7% of nitrogen. The Corg/N ratios of most aggregates were between 7.5 and 12.6, values close to those found in the suspended matter; higher ratios were found in large-size (>5 m) aggregates which are probably older. The content of carbohydrates and proteins determined in the aggregates, respectively, 15.4±8.9% and 7.9±4.8%, w/w, showed a prevalence of carbohydrates over proteins. Neutral carbohydrate analysis of purified polysaccharides from mucilage samples showed very similar signatures with high relative abundance of galactose and glucose. Humic, fulvic and humin substances extracted from the mucilages constitute an important fraction of the organic matter in the aggregates. The humin (a fraction insoluble in acidic and basic media) was present in all mucilage samples, indicating the refractory nature of a part of the organic matter in the mucilage. The iron and calcium could play a role during the aggregation process to form a complex with polysaccharides and humic fractions. The Corg/N ratio 10±2 found in the humic acids extracted from the Adriatic aggregates disclosed a marine origin. The low phosphorus content and the high Corg/P ratio found in the aggregates might depend from high bacteria activity or from the aggregation of organic fractions depleted of phosphorus. The principal inorganic species contained aluminium and silicon, part of which was of biogenic origin and was more significant in the offshore mucilage aggregates than in the coastal ones. The Sibiog/Corg ratio showed that diatoms were always present in the aggregates, although it cannot be established whether these are the producers or these develop within the aggregates. [Copyright &y& Elsevier]

The macroscopic gel phase (mucilage) appears episodically in the northern Adriatic Sea covering tens of square kilometers of sea surface. Current views leave no doubt on phytoplankton production as a proximal source of polymers constituting the gel network, but the mechanism leading to its rapid production remains unknown. We introduced electrochemical sensing of marine microparticles and atomic force microscopy to image supramolecular organization of marine gel network. Our biophysical scenario of mucilage event features self-organization of biopolymers into microparticles ("marine vesicles") that under specific conditions transform to giant gel by a fast vesicle-togel transition. [ABSTRACT FROM AUTHOR]

A 3-year monitoring of dissolved and particulate carbohydrate concentrations in four transects located in the Adriatic and Tyrrhenian Seas was performed in order to get information on the role played by carbohydrates in the mucilage formation in these areas. The application of time series analysis pointed out that the concentration of dissolved carbohydrates does not vary significantly in coincidence of the mucilage appearance showing an almost constant state with respect to time. In contrast, wider temporal variations of carbohydrate amounts, either increase or decrease, were observed when mucilages were lacking or reduced. This almost constant state of carbohydrate amounts observed in presence of mucilages that we define 'steady state' could be associated to an alteration of the complex chemical equilibrium between synthesis and degradation (either hydrolysis or oxidation) reactions of the organic polymers which are typical of the humification processes in the marine environment. The results of this study suggest that the monitoring of carbohydrates can represent an useful tool for the comprehension of the most relevant phenomena of mucilage appearance in the Northern Adriatic Sea. [ABSTRACT FROM AUTHOR]

Water–particle interactions, particle behaviour and short-time scale variability were assessed at a coastal station adjacent to the Emilia Romagna Region (Adriatic Sea) using dissolved and particulate 234Th analyses. The water column was sampled six times between March and September 1997. Measurements showed that 234Th is actively scavenged by particles but the dissolved fraction is always prevalent. Changes in hydrological conditions affect to some degree thorium activities and residence times. Dissolved thorium inventories slowly increased from May to July, then decreased in August, and increased again in September. In July, the formation of a sharp pycnocline associated with low productivity led to high dissolved and very low particulate 234Th activities due to inefficient scavenging. The presence of mucilaginous aggregates, observed in both August and September, may have played a role in scavenging of thorium. In September at 16 m depth, the highest 234Th particulate activity of the study period was measured, probably due to the presence of mucilage. However, the thorium deficit was scarce, due to the small sinking velocity of these aggregates. Both steady-state and non-steady state models were used to calculate residence times for the whole water column and its topmost part (10 m) obtaining strictly comparable results. Residence times in the whole water column are small, ranging from 15 to 45 and from 0.5 to 24 d for dissolved and particulate thorium, respectively. [Copyright &y& Elsevier]

Temporal changes in abundance and biomass of picophytoplankton, heterotrophic pico-eukaryotes, and nanoplankton assemblages were investigated along a transect crossing the Adriatic Sea, from the Italian to the Croatian coast. This 15-months (June 1999-August 2000) investigation allowed comparing microbial parameters during summer 1999 (year without mucilage) and summer 2000 when a major mucilage event occurred. Pico- and nanoplankton assemblages displayed significant differences between the 2 summer periods. The main differences can be summarized as: (i) presence of cyanobacterial blooms (up to 10 8  cells l -1 ) in summer 2000, absent in summer 1999; (ii) an increasing fraction of heterotrophic pico-eukaryotes (up to 5.0 × 10 6  cells l -1 ) and heterotrophic nanoplankton (size 2-5 µm) during mucilage event; (iii) a reduced abundance of small-sized (2-3 µm) phototrophic nanoplankton in summer 2000. Changes in community structure were signals of changes in trophic condition of the system, which resulted in a competitive advantage for small sized pico- and nanoheterotrophs. Data presented here indicated that mucilage events are associated with changes in microbial community structure and functioning in ambient water and induced the amplification of 3-step microbial food chain. The potential use of the heterotrophic pico-eukaryotes for describing alterations of the trophic pathways during mucilage events is discussed. [ABSTRACT FROM AUTHOR]

Carbohydrate contents in seawater, mucilage, and mucilage interstitial waters were analyzed during episodes of mucilage formation in the summers of 2000 and 2001 in the northern Adriatic Sea off Pesaro and in the Gulf of Trieste using 3-methyl-2-benzothiazolinone hydrazone hydrochloride (MBTH) and 2,4,6-tripyridyl-s-triazine (TPTZ) assays. The significant presence of polysaccharides in seawater in the presence of mucilage has an important impact on the agglomeration processes forming gelatinous material (macrogels). Characterization of oligosaccharides in the water-soluble fraction of mucilage using HPLC/RI revealed maltose and pentaose as the main components. [ABSTRACT FROM AUTHOR]

Studies the mucilage that has led to serious problems for the tourism and fishing industries along the coast of the northern Adriatic Sea. Chemical-physical characteristics of mucilage; Determination of the levels of organic matter, organic carbon, carbohydrates and heavy metals.

Focuses on the international research collaboration to examine the factors that may contribute to the mucilage, the biomass that spoils the waters of the Adriatic Sea. Actions taken by scientists in Croatia in response to the mucilage problem; Reasons Italy must cooperate in looking for a solution on the mucilage problem of the Adriatic Sea; Rationale behind the decision of Slovenian biologist Alenka Malej to work on the mucilage problem of the Adriatic Sea.