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The research of sea currents in the Adriatic has a long history. Numerous methods of current measurements as well as indirect methods of current determination were applied. A large number of numerical models were developed to explore variability of the Adriatic current system at various space and time scales. Direct long-term measurement of the sea currents in front of Dubrovnik in combination with the Princeton Ocean Model (POM) adapted for the whole Adriatic were used in this paper to describe a part of very stable Eastern Adriatic Current (EAC) in the coastal area between Dubrovnik and Bar where the coastline is generally oriented in the direction of NW-SE, without larger islands. It was found that at the current meter station with total depth of over 100 m off Dubrovnik, the current directions were dominantly between WNW and NW with very high stability factor, while the most intensive currents were recorded in WNW direction, parallel with the coastline. The maximum current flow near the surface was about 95 cm/s, while at the bottom it was weaker, about 40 cm/s. Intensity and stability of the East Adriatic Current flow in the area between Dubrovnik and Bar, as well as the existence of South Adriatic Cyclonic Gyre over the southern Adriatic Pit were confirmed also by the POM model results. Obtained results imply that all waste that reaches the sea in the coastal area southeast of Dubrovnik will likely pollute the whole area towards northwest.

Air temperature and precipitation patterns from monthly data series collected at 28 in situ meteorological stations in the Adriatic-Ionian region between 1961 and 2015 were mapped by using the self-organizing maps method and connected with hemispheric indices in the atmosphere. Four indices were used: North Atlantic Oscillation (NAO), East Atlantic (EA), East Atlantic/West Russia (EAWR) and Scandinavian (SCA). Two experiments were conducted: the first combined temperatures with the indices and the second combined precipitation with the indices. Both air temperature and precipitation patterns largely exhibit region-wide changes, with more pronounced variability in precipitation than temperature inside the investigated region. The extreme positive and negative anomaly patterns in both precipitation and air temperature are related to hemispheric indices: positive NAO and EAWR and negative SCA indices are responsible for the northern Adriatic droughts and vice versa, while the EA index dominantly drives the extreme air temperature anomaly over the whole central Mediterranean (the positive EA is associated with a pronounced temperature anomaly and vice versa). There is mirroring in the MSLP over Europe between these extreme patterns. Most other precipitation and air temperature patterns that exhibit opposite positive vs. negative anomalies also exhibit opposite associated indices, indicating connectivity between the anomalies and the indices. The relations between hemispheric indices and precipitation anomalies indicate a nonlinear connection, similar to the NAO index, while other hemispheric indices (such as the SCA index) are linearly related to the anomalies.

Croatia was admitted to the International Union of Geodesy and Geophysics (IUGG) soon after gaining independence: its membership status had been provi­ sionally granted by the IUGG Executive Committee already in 1992 and the status was ratified by the IUGG Council at the meeting held in Boulder in 1995. From the beginning, the Croatian Academy of Sciences and Arts was the adhering organization, which supervised the election of members of the Croatian Committee of Geodesy and Geophysics . After being admitted to the IUGG, Croatian geo­ desists and geophysicists took part in the activities of IUGG associations and in the general assemblies . Moreover, they prepared reports on their work, covering four intervals: 1991–1994 (Geofizika, 11, 1994), 1995–1998 (Geodetski list, 53, 1999), 1999–2002 (Geofizika, 18/19, 2001/2002) and 2011–2014 (Geofizika, 32, 2015) . With this report, the practice of informing the IUGG community on Croa­tian geodetic and geophysical measurements and investigations is continued .In the following pages, the work carried out between the years 2015 and2018 by Croatian scientists, active in geodesy and in five geophysical disciplines (geomagnetism and aeronomy, hydrology and physical limnology, meteorology, physical oceanography and seismology), is documented. The report confirms that Croatian geodesists and geophysicists represent a vibrant part of the sci­ entific community: most often their findings are relevant for Croatia and some­times their results and methodological improvements turn out to be useful to colleagues working in other countries . Moreover, the report reveals that the activities of Croatian scientists have expanded recently . Thus, for example, hydrological measurements and modelling have been extended so as to include the Plitvice Lakes – a world­ famous system of sixteen cascading lakes that are subjected to a considerable anthropogenic pressure . Physical oceanographic investigations have been related more closely than before to meteorological studies, with the aim of addressing generation of meteotsunamis and storm surges in the Adriatic Sea and in some other basins . Finally, seismologists and geodesists have strengthened their cooperation, aiming at a combined use of in situ and remotely sensed data in the analysis of seismicity and tectonics of the region . The expansion was apparently stimulated by an improved access to international scientific projects, which supplement the relatively modest na­tional funding of research activities . It is to be hoped that international col­ laboration of Croatian scientists will further intensify in the future and that the IUGG- related activities will contribute to the intensification.

Along the eastern Adriatic coast sea surface temperature (SST) increased by an average of 1.03 °C during the period from 1979 to 2015, while in the recent period, starting from 2008, a strong upward almost linear trend of 0.013 °C/month was noted. During this period, SST increased by 1.25 oC. In the present study, Self-Organizing Map (SOM) procedure was used in analyzing time series (1997-2015) of a number of microbial parameters at two stations with different trophic status in the central Adriatic Sea. The rise in temperature was associated with: (1) the increasing importance of microbial heterotrophic activities and (2) the increasing importance of autotrophic picoplankton (APP) in the MFW. The temperature increase was accompanied with increase of bacterial growth, bacterial biomass turnover, bacterial predator abundances (particularly HNF) and grazing on bacteria, suggesting strong top-down control and increase in the proportion of bacterial carbon channelled to higher trophic levels. Simultaneously, autotrophic picoplankton (APP) biomass (including Synechococcus, Prochlorococcus and picoeukaryotes) significantly increased with temperature, suggesting that APP have a great potential as an additional carbon biomass that can be channelled towards higher levels in the warming conditions.

The Regional Ocean Modeling System (ROMS) was implemented to reproduce physical properties of the area around submarine outlet Stobrec in the middle Adriatic coastal area. ROMS model run was forced with realistic atmospheric fields obtained from meteorological model Aladin, climatological river discharges, tides and dynamics of the surrounding area imposed at the open boundaries. Atmospheric forcing included momentum, heat and water fluxes calculated interactively from the Aladin surface fields during ROMS model simulations. Simulated fields from the Adriatic and shelf scale models were used to prescribe the initial and open boundary conditions for fine resolution coastal domain. Model results were compared with available CTD measurements and discussed in the light of the climatological circulation and thermohaline properties of the middle Adriatic coastal area. Variability in the circulation is related to the prevailing atmospheric conditions, changes in the hydrological conditions and water mass exchange at the open boundaries. Basic features of the coastal circulation are well reproduced by the ROMS model, as well as temperatures and salinities which are within corresponding seasonal intervals, although with lower stratification than measured ones. In order to reproduce dispersion of the passive tracer the ROMS model was coupled with Lagrangian dispersion model. Multiyear monitoring of the physical, chemical and biological parameters around the sewage outlet was used to assess the quality of the dispersion model results. Among measured parameters, redox potential of the surface sediment layer was selected to be compared with model results as its negative values are direct consequence of increased organic matter input that can be attributed to the sewage system inflow.

Planktonic ciliates, as well as the entire microzooplankton size-fraction represent the important components of the planktonic food webs, characterised by high biomass and intensive population dynamics. Due to their ability to adapt rapidly to ecosystem changes, small-sized zooplankton can act as good indicators of the marine ecosystems trophic state. After the activation of new modern sewage system in the eastern part of Kaštela Bay in November 2004, the potential changes in microzooplankton community composition, quantitative structure and seasonal variability were studied for more than a decade. Samples were collected seasonally during three periods: before (2001-2004), after (2005-2008) and ten years after the activation of new sewage system (2015-2017). The changes were best reflected in nonloricate and tintinnid ciliates, evident in the considerably reduced variability of their abundances and increased tintinnid biodiversity in the period after 2004. However, the absence of ciliate summer peaks and reduction of average abundances were statistically significant only at the larger time scale (ten years after). This indicated that apart from the changed trophic state, other environmental parameters affected the microzooplankton community in the period 2015-2017. Changes in seasonal dynamics of the target microzooplankton groups, particularly of ciliates, were confirmed by the Self Organising Map analysis. Further multi-annual investigations (from 2001 onwards) of the trophic relationships within the planktonic food web and the assessment of importance of abiotic parameters are needed for better understanding of the small- sized zooplankton response to environmental changes in this enclosed coastal location.

In this paper we investigated the organic and inorganic P in sediments collected during the 2004-2014 period at fish farms, bays, estuaries, open sea areas, military harbors and nautical marinas to evaluate the environmental status impact on the P distribution in sediments. Granulometric composition, organic matter content and carbonate content as geochemical characteristic were also obtained. Environmental status indexes (CARLIT, that presents the state of coastal biocenosis of macroalgae ; TRIX, that is description of trophic state in the water column and LUSI index, that presents group of anthropogenic pressures in some area) were determined for certain locations. Total P determined for all investigated sediments was 16.0±12.8 μmol g-1 with highest concentrations obtained at fish farm sites. Higher portion of inorganic P (66%) in relation to organic P (34%) was found. Positive correlation was established between total P and sediment organic matter content as well as between organic P and organic matter. Negative correlation was obtained between organic P and carbonate content. These associations were in accordance to previous investigations of P and geochemical parameters in sediment. In sediments at fish farm sites, beside the organic P, inorganic P forms were examined (P in biogenic, authigenic and detrital apatite and P bound to iron oxides and hydroxides). Under the fish farm cages elevated portion of P in biogenic apatite and P bound to iron oxides and hydroxides was found. Obtained portions were attributed to fish farm impact. Association between total P in sediment and environmental indexes (CARLIT, TRIX and LUSI) was established that confirm thesis of the environmental state impact on P in sediment. These results present the basis of the potential implementation of P from the sediment, together with environmental indexes, in assessment of the ecological status of some marine environment.

The Regional Ocean Modeling System (ROMS) was implemented in order to reproduce interannual variability of the Adriatic Sea circulation. Simulations and model result analysis were performed for a three-year period from 1st January 2011 to 31st December 2013. ROMS model run was forced with realistic atmospheric fields obtained from meteorological model Aladin, climatological river discharges, tides and Mediterranean circulation imposed at the southern open boundary. Atmospheric forcing included momentum, heat and water fluxes calculated interactively from the Aladin surface fields during ROMS model simulations. Model results were compared with available CTD and ADCP measurements and discussed in the light of the climatological circulation and thermohaline properties of the Adriatic Sea and its coastal areas. Interannual variability in the Adriatic circulation is related to the prevailing atmospheric conditions, changes in the hydrological conditions and water mass exchange at the Otranto Strait. Basic features of the Adriatic circulation - basin-wide cyclonic circulation with several embedded smaller cyclonic gyres around main pits - are well reproduced by ROMS model. Modelled temperatures and salinities are within corresponding seasonal intervals, although measured profiles generally indicate stronger stratification than modelled ones. Summer circulation in 2011 with current reversal obtained along the eastern Adriatic coast was related to the sampling results of the early fish stages as well as to ARGO drifter movements. Simulated fields from the Adriatic scale model were used to prescribe the initial and open boundary conditions for the interannual simulation in the middle Adriatic coastal domain.

Fitoplanktonska zajednica je zbog svog brzog odgovora na promjene u okolišu pouzdan pokazatelj stanja okoliša i jedan je od bioloških elemenata koje za procjenu kvalitete vode propisuje Okvirna direktiva o vodama (ODV). Kako bi se testirao odgovor fitoplanktonske zajednice na antropogene pritiske s kopna, multivarijatne statističke metode korištene su za analizu koncentracije klorofila a, brojnosti i sastava fitoplanktonske zajednice u odnosu na antropogeni utjecaj i ekološke varijable kao što su temperatura, slanost i hranjive soli. Analizom su obuhvaćene postaje različitog stupnja opterećenja, a preliminarna procjena antropogenog utjecaja na istraživanim postajama je određena preko LUSI indeksa (Land Use Simplified Indeks). Multivarijatna analiza je pokazala da su koncentracije hranjivih soli nitrata i silikata pouzdan pokazatelj utjecaja slatke vode, dok su biomasa i brojnost fitoplanktonske zajednice pouzdan pokazatelj antropogenog utjecaja. Odgovor bioraznolikosti fitoplanktonske zajednice nije bio linearan, a najveća biorazmolikost zabilježena je u srednje eutrofnim odnosno mezotrofnim područjima. Kanonička analiza korespondencije identificirala je sljedeće vrste kao indikatore porasta eutrofikacije: Skeletonema costatum, Scrippsiella trochoidea, Guinardia flaccida, Leptocylindrus spp., Prorocentrum spp., Proboscia alata, Eutreptiella spp. i Pseudonitzschia spp.

In the framework of the project PERSEUS (Policy-oriented marine Environmental Research in the Southern EUropean Seas), two interdisciplinary surveys were carried out in April 2013 and April 2014 in the middle Adriatic Sea along the Pescara-Sibenik transect (Jabuka Pits area) and Vieste-Split transect (Palagruza Sill area) with Croatian research vessel "Bios II" and the Italian research vessel "G. Dallaporta", respectively. The main objective of these research cruises was the implementation of the Marine Strategy Framework Directive (MSFD) in the Adriatic region for collecting physical, chemical and biological data in order to get a better understanding of whole Adriatic ecosystem. The two transects are already recognised as a key areas for the interception and the study of dense water modification (Zore-Armanda, 1963 ; Marini et al., 2006 ; Grilli et al., 2013). Due to seasonal circulation patterns, they are characterized by high temporal variability of the thermohaline structure (Grbec and Morović, 1997 ; Vilibić, et al., 2004) and other oceanographic parameters. Long term oceanographic records from the Middle Adriatic enable better understanding of the ecosystem response to changes of atmospheric and sea conditions through physical, chemical and biological processes (Marasović et al., 1995). Several oceanographic parameters relevant and useful for the ecosystem assessment of the two areas (temperature, salinity, density, fluorescence, oxygen, nutrients, chlorophyll, phyto- and zoo-plankton as well as selected pollutants , trace metals and Polycyclic Aromatic Hydrocarbons-PAHs in sediments) were collected. In the present work, the variations of PAHs and trace metals concentration in the marine sediments are presented in relation to the physical and chemical characteristics of the bottom layer. A constant influx of metal induces more intense accumulation of anthropogenic metals, especially Cd, in sediment from Jabuka Pit, and the metal content slightly increases towards the Italian coast. The total PAHs concentrations (sum of 16 PAH priority pollutant - US EPA) recorded in the marine sediments during the cruise in April 2013 showed a higher level of PAH contamination in the pits, especially in the central pit (28.5 ng/g d.w.), in comparison to others analyzed samples. The corresponding bottom water in the central pit is characterized by a temperature of 10.9°C, density of 29.6 kg/m3, salinity of 38.6 and low values of DIN (0.55 μmol∙l-1). The linear regression between DIN and PAHs showed a significant negative relationship (p ≤ 0.05). This feature implies a possible accumulation of PAHs very likely due to a lower microbial activity as demonstrated by Xu et al. (2014). The physical and chemical characteristics of the bottom layer in these areas could influence the PAHs contamination of the deep sediments.

In September 2011 during routine monitoring of commercial purse seine catches 87 fingerling specimens of scombrids were collected in the southern Adriatic Sea. Sequencing of mitochondrial control region locus inferred that specimens belonged to the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) (N=29), bullet tuna, Auxis rochei (Risso, 1810) (N=30) and little tunny, Euthynnus alletteratus, Rafinesque, 1810 (N=28). According to their body length and previously published growth parameters, we estimated their age to be approximately 30 days, which would suggest that they were spawned in the Adriatic Sea, contrary to standard knowledge. Hence, in order to determine possible location of the spawning we run coupled modelling system ROMS-ICHTHYOP. Realistic ROMS simulations were made to provide current and density fields for the ICHTHYOP model. ROMS model was forced with river inflows, tides, exchange through the Strait of Otranto and realistic surface air-sea fluxes calculated from fine resolution ALADIN model. ICHTHYOP was run in the backward mode for 30 days using published investigations on the studied species and its early stage dynamics, such as their growth and developmental stage thermal dependence, lethal temperatures, etc. Apart simulations with coupled modelling system, detailed analysis of prevailing meteorological and oceanographic conditions was made using all available data. Comparison to climatology of the area approved that 2011 had unusually prolonged warm and dry summer season. Occasional inflows of hot and dry air from the northern Africa additionally warmed up Adriatic atmosphere. Under these conditions sea surface temperature was up to 2 standard deviations above normal. In the deeper layers, high temperature and salinity were recorded.

Jadran je poluzatvoreno more koje je zbog svog položaja duboko uvučenog u europsko kopno vrlo osjetljivo na atmosferski stres te na nagle i postupne promjene klime. U sjevernom Jadranu, zbog njegovih kontinentalnih osobina, utjecaj klimatskih promjena, a posebno ekstremnih situacija jače je izražen nego u srednjem, odnosno južnom Jadranu, gdje je taj utjecaj donekle umanjen i usporen. No, činjenica je kako se zadnjih desetljeća uočavaju znatne promjene temperature zraka i oborine kao posljedica promjena atmosferske cirkulacije nad sjevernom hemisferom što se povezuje s klimatskim promjenama globalnog karaktera. Efekti tih promjena uočljivi su u cijelom vodenom stupcu Jadranskog mora, posebno na promjenama temperature, saliniteta i kisika srednje-dubokih slojeva Jadrana. Analizirajući višegodišnje promjene temperature zraka i oborine, temperature mora i saliniteta dubljih slojeva te uspoređujući ih s procesima na hemisferskoj skali, uočen je kontinuirani porast prizemne temperature zraka i nelinearni trend oborine od kasnih 80-ih godina prošlog stoljeća. Uz temperaturu mora i salinitet, sadržaj otopljenog kisika dobar je pokazatelj starosti vodenih masa pa time i atmosferom uvjetovanog prozračivanja Jadrana. U promatranom razdoblju uočeno je više ekstremnih meteoroloških situacija, od kojih je ona zabilježena zimi 1987. godine bila odgovorna za promjenu režima termohaline cirkulacije Jadrana.

PREDGOVOR Nebo. Gledano sa Zemlje njegov je svod često pokriven malenim kapima i kristalićima leda raznolikih oblika koji se pojavljuju i nestaju tvoreći svima znane oblake. Niske, visoke, prozračne. Pojavljuju se u nebrojeno mnogo oblika, golemi su ili maleni, različitih boja, nalaze se na različitim visinama, nisko pri tlu, na velikim visinama troposfere i stratosfere. Kada razmišljamo o njima prva je asocijacija – pamučna čupava nebeska gruda. No, odlučimo li preciznije zaviriti u njihovu unutrašnjost, zapitamo li se zašto se pojavljuju i zašto baš u takvom, nikad ponovljenom obliku, suočit ćemo se sa složenom slikom životnog ciklusa svih tih po obliku, visini i razvijenosti različitih tvorevina vodene pare. Knjiga Oblaci namijenjena je svima onima koji su se bar jednom, pogledavši u nebo, zapitali kako nastaju oblaci, zašto ih vidimo i zašto nestaju. Nadamo se kako će biti koristan materijal studentima Sveučilišnog studijskog centra za studije mora koji se s oblacima susreću slušajući kolegij Osnove meteorologije kao i studentima srodnih fakulteta. Uz cjeline koje opisuju procese važne za nastajanje i prostiranje oblaka knjiga sadrži mali atlas oblaka – međunarodno prihvaćenu podjelu u odnosu na visinu donje baze oblaka prema klasifikaciji Svjetske meteorološke organizacije. Oblaci snimljeni tijekom nastajanja ove knjige klasificirani su po rodovima, vrstama, podvrstama te njima pridruženim dodatnim osobinama i oblacima pratiocima. Obrađeni su troposferski oblaci dok su opisani samo polarni stratosferski oblaci koji svojom neobičnošću često plijene pažnju promatrača. Knjiga je nastala sa željom da se premosti nedostatak slične literature na hrvatskome jeziku. Smatramo kako ovaj kratak pregled klasifikacije oblaka može pomoći studentima pri određivanju roda, vrste i podvrste oblaka čemu nesumnjivo pridonose fotografije oblaka većinom snimljene nad Jadranom. Oblacima su pridružena latinska imena koja opisuju značenje osobina koje oblaci nose. Primjerice latinski prefiks alto ili cirro općenito znači visinu na kojoj se oblaci nalaze. Oblaci čija latinska imena počinju sa cirro (cirrocumulus, cirrus, cirrostratus) odnose se na oblake u visokim slojevima troposfere, oni s pefiksom alto na početku imena (lat. altostratus, altocumulus) oblaci su srednjeg sloja. Ponekad ime oblaka znači i opisuje njegovu glavnu osobinu kao što je to slučaj s kumulus humilis oblakom koji počinje kao vrlo mali, a može narasti do kumulus kongestus (lat. cumulus congestus) oblaka koji se daljnjim razvojem može pretvoriti u olujni oblak latinskog naziva cumulonimbus. Tako od bezopasnih oblaka lijepog vremena uz povoljne atmosferske uvjete te izraženu atmosfersku nestabilnost nastaje prava meteorološka bomba, olujni vertikalno vrlo razvijen kumulonimbus. Oblaci svoje osobine „crpe“ iz fizikalnih procesa koji su prethodili njihovom stvaranju i onih koji su razlogom njihovog razvoja ali i njihovog nestajanja. Stoga je poznavanje fizike atmosfere preduvjet razumijevanja životnog ciklusa oblaka. Gledajući oblake „gledamo“ fizikalne zakonitosti koje su razlogom njihovog postojanja. Preporučujemo studentima da u tom svjetlu promatraju nebo – biti će im zanimljivije, a moći će i sami „uhvatiti“ neponovljivi trenutak neke lijepe realizacije fizikalnog atmosferskog procesa. autori

During routine monitoring of commercial purse seine catches in 2011, 87 fingerling specimens of scombrids were collected in the southern Adriatic Sea. Sequencing of mitochondrial control region locus inferred that specimens belonged to the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) (N=29), bullet tuna, Auxis rochei (Risso, 1810) (N=30) and little tunny, Euthynnus alletteratus, Rafinesque, 1810 (N=28). Due to previously published growth parameters, age of collected specimens was estimated to be approximately 30 days. In order to determine possible location of the spawning event coupled modelling system ROMS-ICHTHYOP was run. Realistic ROMS simulations were made to provide current and density fields for the ICHTHYOP model. ROMS model was forced with realistic surface air-sea fluxes calculated from fine resolution ALADIN model, river inflows, tides and external dynamics. ICHTHYOP was run in the backward mode for 30 days using published investigations on the studied species and its early stage dynamics, such as their growth and developmental stage thermal dependence, lethal temperatures, etc. Apart simulations with coupled modelling system, detailed analysis of prevailing meteorological and oceanographic conditions was made using all available data. Comparison to climatology of the area approved that 2011 had unusually prolonged warm and dry summer season. Occasional inflows of hot and dry air from the northern Africa additionally warm up Adriatic atmosphere. Under these conditions sea surface temperature was up to 2 standard deviations above normal. In the deeper layers, high temperature and salinity were recorded. According to performed simulations it seems that tuna species spawn within the commercial tuna cages (this is not the first evidence of natural spawning within commercial tuna farming facility in the Adriatic), while the other two species most probably opportunistically use positive environmental (abiotic and biotic) conditions and spawn in the same area.

Croatia was admitted to the International Union of Geodesy and Geophysics (IUGG) soon after gaining independence: its membership status had been provisionally granted by the IUGG Executive Committee already in 1992 and the status was ratified by the IUGG Council at the meeting held in Boulder in 1995. From the beginning, the Croatian Academy of Sciences and Arts was the adhering organization, which supervised the election of members of the Croatian Committee of Geodesy and Geophysics. After being admitted to the IUGG, Croatian geodesists and geophysicists took part in the activities of IUGG associations and in the general assemblies. Moreover, they prepared reports on their work, covering three intervals: 1991–1994 (Geofizika, 11, 1994), 1995–1998 (Geodetski list, 53, 1999), and 1999–2002 (Geofizika, 18/19, 2001/2002). After an eight-year break, the practice of reporting to the IUGG is reestablished with this report. In the following pages, the work carried out between the years 2011 and 2014 by Croatian scientists, active in geodesy and in five geophysical disciplines (geomagnetism and aeronomy, hydrology, meteorology, physical oceanography, and seismology), is documented. The report shows that Croatian geodesists and geophysicists represent a vibrant part of the scientific community: most often their findings are relevant for Croatia and sometimes their results and methodological improvements turn out to be useful to colleagues working in other countries. The four-year output is impressive, having in mind the recent decline in national funding of research activities. It appears that the problem was partially offset by an improved access to international research projects. Although the international projects could complement but could not replace the national projects, it is to be hoped that the international collaboration of Croatian scientists will expand in the future and that the IUGG-related activities will contribute to the expansion.

Glycymeris bimaculata is one of the largest (up to ~110mm) bivalves in the Mediterranean Sea yet there is a paucity of information about the growth of the species. The principal objectives of this study were: i) to assess the periodicity and timing of growth line formation in G. bimaculata collected from Pag Bay in the Adriatic Sea using stable isotope analysis and a statistical cross-match between the growth increment series (GIS) of individuals live-collected in 2008 and 2012, ii) to construct a statistically robust sclerochronology from G. bimaculata growth increment series, iii) to investigate changes in shell growth in response to environmental factors, and iv) to estimate growth parameters and the maximum longevity of the species. The age of 55 shells (ranging in length between 49.1 and 109.5 mm), determined from acetate peel replicas of polished and etched shell sections, ranged in age between 6 and 57 years. The reconstructed seawater temperature records derived from oxygen isotope analysis of the growth increments and lines demonstrate that the lines visible in shell cross section are deposited annually in late autumn. Further confirmation of an annual periodicity of growth line formation was obtained when GIS from shells collected in 2008 and 2012 cross-matched statistically with a positive correlation at a 4 year offset. A master chronology containing growth increment data for the period 1991 to 2007 derived from nine individuals, ranging in age from 17 to 34 years, was constructed with a mean Expressed Population Signal (EPS) of >0.85. The GIS of the analyzed specimens had pronounced inter-annual variability with the period from 1997 to 1999 characterized by slower growth and the period from 2000 to 2005 by moderate growth, while growth increments deposited in the years 2006 and 2007 were widest. Differences in growth between periods were related to temperature and salinity data. The growth of G. bimaculata is described by the von Bertalanffy growth equation relating length Lt at time t: L t= 90.85(1-e-0.10 (t+3.13)).

Biomonitoring of contaminants (Cd, Pb, Cu, Zn, Cr, HgTOT, lindane, PCBs and DDTs ) in shellfish, Mytilus galloprovincialis, was conducted at 18 sites distributed across the entire coastal area of Croatia once a year over the period 2000-2009. Based on the obtained data pertaining to metal levels in shellfish, it can be concluded that the best status was observed at sites located in the outer estuaries of the Neretva and Krka rivers as well as in the Lim Bay area under submarine freshwater influence, while the poorest status was observed in the areas under anthropogenic impact, e.g. ports, semi-enclosed bays and industrial areas. Statistical analysis of data showed an upward trend for all metals during the period of investigation. The increase in metal concentrations appears to be the result of enhanced industrial activity during the indicated time period, mostly metal production and processing industry which showed more than 190 % growth throughout the period from 2000 to 2008. Analysis of data with regard to organic pollutants in shellfish revealed lower concentrations of lindane in comparison with DDT, while concentrations of PCB compounds (Aroclor 1254 + Aroclor 1260) were significantly higher in relation to chlorinated pesticides. Highest concentrations of organic pollutants were, similar to metals, established in the areas under anthropogenic influence, however, a decreasing trend was observed at most sites. The decrease in the levels of chlorinated pesticides (lindane, DDT compounds) was more distinguished, which was to be expected considering that the use of lindane has been banned in Croatia since 2001, while the ban on the use of DDT was enforced in 1972. Moreover, there is no national legislation prohibiting the import and use of PCB compounds.

Present study describes the phytoplankton community structure and phytoplankton abundance in three bays on the eastern Adriatic coast (Šibenik Bay, Kaštela Bay and Mali Ston Bay) during 2005. The highest phytoplankton biomass (expressed as chlorophyll a) were recorded at one station in Šibenik Bay (4.73 mg m-3), and in Kaštela Bay (2.79 mg m-3), while at all other stations recorded values were generally below 1 mg m-3. At the investigated area of Šibenik Bay a total of 114 phytoplankton taxa have been determined. The most diverse were diatoms with 61 and dinoflagellates with 37 taxa. Coccolithophorids contributed with 6, cryptophytes with 3, silicoflagellates, euglenophytes and chlorophytes with 2 taxa. In the area of Kaštela Bay 193 phytoplankton taxa have been recorded. Dinoflagellate group was the most diverse with 92 taxa, followed by diatoms (80), coccolithophorids (9), silicoflagellates and euglenophytes (4), cryptophytes (2) and chlorophyte (1). In the area of Mali Ston Bay a total of 88 phytoplankton taxa have been found, with 39 diatoms, 36 dinoflagellates, 2 silicoflagellates, 4 coccolithophorids, 2 euglenophytes, 1 chllorophyte and 3 chrisophyte taxa. Abundance of dinoflagellates was very low in this area. Coccolithophorids contributed more to the community composition in Mali Ston Bay, then in other areas of research. A diverse microflagellate group was present in the whole area of investigation with a high frequency of findings. During the investigated period a relatively small number of monospecific blooms in all areas have been recorded. The largest numbers of taxa were recorded at stations that are under an influence of freshwater input from rivers and strong anthropogenic influence.

The objectives of this paper were to determine the main environmental drivers of zooplankton variability in coastal waters adjacent to urban areas and to evaluate the differences in zooplankton abundance and population structure in relation to chemical and biological parameters in the water column. Samples were collected seasonally from May 2006 to January 2009 at 8 sampling sites in the bays and channels along the eastern Adriatic coast. Zooplankton population structure showed high similarity within the investigated region, especially evident in the homogeneity of copepod community composition, where relative importance of the individual species showed characteristic high ranking of small and medium-sized taxa. Zooplankton numerical variability primarily responded to seasonal variation in water temperature and spatial variation in salinity, but spatial distribution of the collected data showed that abundances were also linked to chemical and biological parameters generally used as descriptors of water quality. This indicates that zooplankton community size reflects the trophic status of an area and supports the use of zooplankton studies as an auxiliary method in the evaluation of the trophic state of coastal waters.

An investigation into the spatial distribution of copepod abundance, using an “Adriatic Trap”, in the epipelagic layer of the south Adriatic Sea, was performed during 4 cruises at 5 stations from April 1993 to June 1994. Samples were collected at 1, 5, 10, 20, 50, 75, and 100 meter depths. Nauplii were the most abundant identified at all stations and depths, corresponding to an average of 69-81% of all copepod individuals. With respect to the total number of postnaupliar copepods, the 0-50 m layer was dominated by specimens of calanoids (49.7%), while in the 50-100 m layer, the most abundant taxa were cyclopoida-oncaeids (31.5%), cyclopoida-oithonids (23.5 %) and harpacticoids (6.7 %). Our research also clearly indicates that copepodites and small adult copepods, such as: calanoids, Paracalanus parvus, Clausocalanus paululus, oithonids Oithona similis, Paroithona parvula, oncaeids Monothula subtilis, Oncaea zernovi, Spinoncaea ivlevi and harpacticoids Microsetella norvegica, M. rosea were particularly dominant in euphotic zone. Consequently, problem the loss of small and undeveloped copepods through standard plankton nets that other quantitative methods must be utilised for an objective evaluation of total copepod population.

The Adriatic Sea is of exceptional importance for Croatian economy as a resource for fisheries, tourism, transport and other goods. For these and many other reasons it is important to control its ecological state and preserve its biodiversity. Croatian Environmental Protection Agency together with a number of institutions has organized collection of environmental data. The reports, data and graphs can be viewed at the web (http://jadran.izor.hr/azo/).The Institute of Oceanography and Fisheries Split (IOF) and Institute Ruđer Bošković, Rovinj (IRB), are in charge of marine data acquisition and IOF is in charge for the marine database. Here we present some of the results from the last few years collected at twenty east Adriatic coastal stations and one middle Adriatic open sea station. Discussed are oxygen saturation, nutrients, chlorophyll a concentrations, suspended matter and transparency. Statistical analysis for the period 2005-2009 is compared to the long-term mean/median values. High spatial and seasonal variability of the parameters is discussed in relation to location of the stations regarding possible anthropogenic impact. Connection to the hydrodynamics is also discussed. Correlations, PCA and other analysis gave some new indications of the relations among parameters.

Occurrence of Dinophysis species in relation to hydrographical data in the northeastern Adriatic Sea have been investigated in a period from 2001 to 2005. D. caudata appeared in the community during stratified summer period. Dinophysis species abundances show significant correlation with surface and bottom salinity differences (Δs). Higher abundances of Dinophysis species and its longer abidance in the phytoplankton community have been recorded in offshore station in relation to inshore stations. More abundant Dinophysis population in offshore area is associated with higher salinity differences between surface and bottom layer. These findings suggest that offshore conditions in association with increased surface salinity are more favorable of bloom origin than inshore conditions.