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To evaluate and monitor the presence of non- indigenous species (NIS) in harbors and marinas, Autonomous Reef Monitoring Structures (ARMS) were deployed in two sites, a commercial harbor and a touristic marina in the port of Ravenna (Italy, northern Adriatic Sea), in two seasons and left about 2 m underwater for three months. Significant differences in sessile and vagile community structures were found between sites and times. Out of 44 taxa identified, two sessile and five vagile NIS were found. Among them, the polychaete Schistomeringos cf. japonica (Annenkova, 1937) could represent the first Mediterranean record if confirmed by further analyses.

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.

Present study is a part of comprehensive research within National WFD monitoring of Transitional Waters (TW) in Croatia. It refers to the soft- bottom macrobenthos from the selected TWs situated along the eastern coast of the Adriatic Sea (AS), i.e. Rječina (northern AS), Jadro (central AS) and Neretva (southern AS) TW. All sampling sites were situated in areas of diverse anthropogenic pressures, including moderate urban and industrial pollution, maritime transport and port activities. Sampling was performed during 2016-2019 campaign, using Van Veen grab (0.1 m2). Preliminary separation of macrofauna was performed on board, by rinsing of the sediment on the 1 mm mesh sieves. Additional samples were taken for sediment analyses: ORP, organic matter and granulometric composition of sediment. The material retained on sieves was fixed with 4% seawater solution of formaldehyde and then processed after standard laboratory procedure: complete separation, sorting, counting and taxonomic identification of macroinvertebrates. The results of qualitative and quantitative, structural and functional analyses (taxonomic composition, abundance, species richness, diversity, functional composition) are provided. Statistical analysis of communities’ structure and analysis of the Ecological Quality Status were performed using Primer V software and AZTI application and database. At all sites, macrobenthic communities were characterized by predominance of Annelida and Mollusca, that together comprised 77-94 % of total macrofauna. The abundance and number of species were close at all sampling sites, but they differ in species composition. In the research area, Ecological Quality Ratio (EQRAMBI) based on the Biological Quality Element (BQE) benthic invertebrates indicated moderate to high Ecological Quality Status. However, TWs are naturally stressed environments, inhabited by species adapted to stress conditions. Until now, there is no adequate methodology for distinction of natural and anthropogenic impact on the macroinvertebrates in TWs. In this regard, further research is needed.

One of the largest and most preserved floodplains of the Danube, Kopački Rit, has characteristic wetland habitats (lakes, channels, river side arms) that function as a highly significant subsystem of the floodplain complex. Such complexity supports very high biodiversity of aquatic organisms, influenced by the Danube’s water-regime. In July 2013, after one of the extreme floods (starting in June), waters from the parent river, trapped within the Rit, enabled the development of atypically abundant, dense, floating macrophyte mats. Sampling was conducted (with a cylindrical core) on the 2nd, 4th, 8th and 12th of July – when the canopy dispersed, at three sites in Kopačko lake and Čonakut channel. Standard physico-chemical water parameters were measured in situ, and the laboratory analyses included isolation and identification of plant material and macroinvertebrates, and chlorophyll analysis. Plant material was dried at 105°C for 24h to assess the dry weight. Twenty-seven invertebrate taxa were recorded, of what 14 belonged to Insecta. In total, 7370904 ind./100g d.w. were sampled, most abundant being Cladocera, Copepoda and Chironomidae larvae. The floating plant canopy provided perfect refugium and food source for the invertebrates. NMDS analysis (invertebrate abundance, Bray-Curtis similarity matrix) displayed the grouping of sampling dates and the statistical significance was confirmed by ANOSIM analysis. There was no difference in-between the sites or water bodies. The most important environmental parameters influencing community structure were water temperature and the Danube water-level, which decreased, thus causing the outflow of waters from the floodplain and the dispersal of this interesting community.

The present study aimed to ; 1) assess the potential impact of drilling on the soft-bottom benthic community in the North Adriatic gas field (44°41.7’N - 13°16.1’E ; 44 m depth) and 2) to provide a baseline for assessment of environmental impact related to the future gas exploitation. The structural and functional characteristics of the macrobenthos were studied at eight sampling sites arranged in a star shaped formation around a drill hole at 100 m distance in N, S, E, W directions, and at 300 m distance in SW, NW, NE, SE directions. Samples were taken with the Van Veen grab (sampling area of 0.1 m2). At each site, we obtained four replicate samples for qualitative and quantitative analysis of macrofauna, and samples for sediment analyses. Macrobenthic community structure was analysed using univariate, multivariate and distributional techniques ; functional diversity following classification by Grall and Glémarec (1997) and ecological status was assessed using AMBI and M-AMBI biotic indices. Results indicated no differences in macrobenthic structure among sampling sites, both related to distance from the drill hole (100 and 300 m) and sampling time (before and after installation of gas platform). All study sites can be ranked into the class of high ecological status. This study should provide objective benchmarks for potential environmental impact on the poorly sorted sand community in the Northern Adriatic offshore waters, as well as for ecological status assessment.

Seaports are recipients of myriad organic and inorganic pollutants that directly or indirectly released into marine environment. Recently, maritime transport and associated port activities are recognized as increasing source of environmental threats, with ballast water as one of main vectors for initial transport of non- indigenous species (NIS). The goal of this study was to characterize benthic communities associated with hard- and soft- bottom habitats from the four North Adriatic seaports and to check the presence of non- indigenous species. The sampling strategy and methodology followed modified CRIM Protocol (Hewitt and Martin, 2001). Total of 17 higher macrobenthic taxa, and 75 species were identified from the hard substrata, and much less (10 higher taxa, 36 species) from the soft bottom. The results of univariate analyses suggested occurrence of modified and impoverished soft- bottom macrofauna and rather diverse hard bottom fauna. Multivariate analysis indicated significant differences of macrofauna communities among surveyed ports. In total, seven NIS were detected, all belonging to polychaetes. One of them, Platynereis nadiae was recorded for the first time from the Adriatic Sea and it was found in ports of Bakar, Omišalj and Rijeka. Six NIS were reported from the port of Raša: Hydroides dianthus, H. elegans, H. stoichadon, Leiochrides australis, Protolaeospira striata and Pileolaria berkelyana, and the last one was recorded for the first time in the Adriatic Sea.

Ihtiocenoze predstavljaju jedan od ključnih elemenata u funkcioniranju lentičkih ekosustava, osiguravajući protok energije i proces recikliranja nutrijenata. Istraživanje sastava i strukture ihtiocenoze provedeno je tijekom srpnja 2014. godine u Kopačkom jezeru, Park prirode Kopački rit. Ispitan je sastav probavila riba kako bi se utvrdila važnost pojedinih kategorija hrane u njihovoj ishrani, s obzirom da ribe svojom ishranom mogu utjecati na bentos i obraštaj. Uzorkovanje je provedeno pomoću trostruke poponice, postavljene tijekom večeri da stoji 12 sati, koja je potom izvučena. Uzorkovani primjerci riba fiksirani su u 4%‐tnom formaldehidu radi kasnije obrade u laboratoriju. Ribolovni napor (CPUE) iznosio je 2, 71 kg/mreža‐sati. Tijekom istraživanja su uzorkovane 143 jedinke, starosti između 1+ i 6+ godina. Utvrđeno je 9 različitih vrsta koje pripadaju porodicama: Esocidae, Cyprinidae i Percidae. Najbrojnija vrsta je bila Blicca bjoerkna, s uzorkovanih 50 jediniki. Također, zabilježen je veći broj mužjaka nego ženki. U probavilima riba utvrđene su različite kategorije hrane: vegetacija, detritus, beskralježnjaci, uz dominaciju ličinki kukaca, te ribe. Prema sastavu probavila, uzorkovane ribe možemo klasificirati kao omnivore, bentivore te piscivore. Također, pronađeni su i endoparaziti u jedinkama vrsta B. bjoerkna, Alburnus alburnus i Gymnocephalus baloni. Zabilježena ihtiofauna karakteristična je za područje i stanište istraživanja, a utvrđene hranidbene navike ukazuju na različite važne izvore hrane za pojedine vrste riba.

Floodplains are extremely complex and diverse ecosystems connecting terrestrial and aquatic habitats ; with very complex interactions and trophic relationships between different groups of organisms. Chironomids are considered to be important part of every freshwater ecosystem due to their role in connecting higher and lower trophic levels, feeding on algae, detritus or smaller invertebrates and protozoans, whilst being food for predatory amphibian larvae or fish. Preliminary research of the role of chironomids in fish diet has been conducted in the Kopački Rit Nature Park (Croatia), a large flooding area of the Danube, during autumn and winter period of 2013. We wanted to determine the proportion and, hence the importance, of chironomids in the fish diet by examining their stomach contents. Due to the low water level and low temperatures, large fish were scarce in the catch. A total of 8 fish species were sampled aged from 0+ to 3+, most abundant being Blicca bjoerkna L. 1758 of age 0+. We determined three main food chategories in the diet of the sampled fish, but chironomids were not the main food source. Probable reasons are low abundance of larvae in the sediment (and lack of periphyton and macrophyte), size and age of the sampled fish and low temperatures which cause cessation of feeding. Sediment samples were also taken at the research sites. Benthic fauna comprised of nematodes, oligochaets, copepods, chironomid larvae and few specimens of Ceratopogonidae and Chaboridae larvae. Chiromidae community was mostly represented by Tanytarsini and Chironominii larvae, what is consistent with qualitative composition in diet samples. High temporal variability in chironomid community requires all seasons to be included in fish diet analysis.

Poplavna i močvarna područja jedna su od najbogatijih po pitanju biološke raznolikosti. Nastanjuju ih mnoge vrste i čine vrlo kompleksne hranidbene mreže. Uloga riba u funkcioniranju tih mreža je golema i tek je nedavno do kraja prepoznata. Ribe imaju ključnu ulogu u povezivanju viših i nižih trofičkih kategorija unutar hranidbene mreže, kao i različitih hranidbenih mreža kopnenih i vodenih ekosustava. Također, osiguravaju kruženje ugljika unutar vodenih ekosustava i recikliranje minerala i nutrijenata, te normalan proces sedimentacije. Brojnost i sastav unutar ihtiocenoze nekog staništa može ukazivati na stanje kvalitete vode. Park prirode Kopački rit veliko je poplavno i močvarno područje u trokutu što ga zatvaraju Drava i Dunav. Flora i fauna ovoga područja istražuju se dugi niz godina, međutim, neke skupine, poput riba, slabo su istražene. Posljednji podatci o ihtiofauni Posebnog zoološkog rezervata unutar Parka potječu iz 80- ih godina prošloga stoljeća, dok za područje Parka izvan Posebnog zoološkog rezervata niti ne postoje objavljeni podatci. Iz tog je razloga u jesen 2009. godine, uz kraći prekid, započeto sustavno istraživanje riba u i izvan područja Posebnog zoološkog rezervata Parka prirode Kopački rit. Istraživanje je nastavljeno u jesen 2013. godine te traje i dalje. Preliminarni podatci govore o velikoj brojnosti riba. Ustanovljena je prisutnost 23 vrste iz osam porodica, a ukupan broj ulovljenih jedinki iznosio je 4957. Očekivano, najzastupljenija je porodica Cyprinidae s 14 vrsta, a slijede ju porodice Cobitidae i Percidae s po dvije vrste. Ostale porodice bile su zastupljene s jednom vrstom. Dominirala je krupatica, Blicca bjoerkna (L., 1758.), s 38.4%, a slijedile su uklija, Alburnus alburnus (L., 1758.), sa 17.3% i babuška, Carassius gibelio (Bloch, 1782.), s 15.8%. Babuška je ujedno bila i najbrojnija alohtona vrsta, a brojnost joj je nešto manja nego je utvrđena drugim istraživanjima provedenim u Kopačkom ritu u ovom vremenskom periodu. Uz babušku, utvrđena je prisutnost još tri alohtone vrste. Ukupan udio jedinki alohtonih vrsta iznosio je 18.2%.

Unazad nekoliko desetljeća četiri vrste iz porodice glavoča (Gobiidae) proširile su svoj areal uzvodno Dunavom i pritocima. Tijekom istraživanja ihtiofaune početkom travnja 2011. godine na području Drave, od ušća do 12. rkm, te Dunava kod Aljmaša (rkm 1378.) utvrđena je prisutnost četiri vrste iz porodice glavoča od kojih se jedna smatra autohtonom – Proterorhinus semilunaris (Heckel, 1837), a ostale tri pripadaju rodovima Neogobius, Babka i Ponticola. Vrsta Neogobius melanostomus (Pallas, 1814) bila je prisutna na četiri, Babka gymnotrachelus (Kessler, 1857) na jednom, a Ponticola kessleri (Günther, 1861) na dva od ukupno 11 lokaliteta. Za uzorkovanje je korišten elektroagregat. Ukupno je ulovljeno 1130 jedinki. Utvrđeno je 28 vrsta riba i 1 vrsta paklara. Glavoči su činili 0, 04 % ulova. Najbrojnija je bila vrsta Neogobius melanostomus [broj jedinki: 25 (2, 21 %) ; max. SL: 90 mm ; min. SL: 40 mm ; srednja duljina tijela: 60.7+-19.3]. Slijedila je vrsta Ponticola kessleri [broj jedinki: 21 (1.86%) ; max. SL: 135 mm ; min. SL: 47 mm ; srednja duljina tijela: 90+-28.9]. Ulovljene su samo dvije jedinke Babka gymnotrachelus (0.18% ; max. SL: 86 mm ; min. SL: 77 mm ; srednja duljina tijela: 81.5+-6.4). Sve tri vrste lovljene su na kamenitoj obali. Prema dosadašnjim podatcima, vrsta N. melanostomus nova je za faunu Drave. Vrsta B. gymnotrachelus uzorkovana je u kanalu koji povezuje Staru Dravu Bijelo Brdo s Dunavom, nekoliko stotina metara nizvodno od ušća Drave u Dunav. Također, nalaz ove vrste podupire tezu o polaganom uspostavljanju populacije na ovom području s obzirom da je tijekom prijašnjih istraživanja, duž cijelog toka Dunava u Hrvatskoj, ulovljena samo jedna jedinka. Nije opovrgnuta teorija o disjunktnim populacijama, s obzirom na mjestimično veliku brojnost jedinki pojedinih vrsta, kao ni teorija o širenju balastnim vodama jer je 80.4 % jedinki ulovljeno kod luke Tranzit. S obzirom na istraživanja o učinkovitosti elektroribolova za uzorkovanje vrsta roda Neogobius, Babka i Ponticola, možemo zaključiti da je brojnost utvrđena ovim istraživanjem samo 16-50 % stvarne veličine populacija, ovisno o vrsti.

Aljmaški rit je poplavno područje u desnom zaobalju rijeke Drave od njezina 12.rkm do ušća s Dunavom. Prostire se od naselja Sarvaš sve do Aljmaša, na oko 26 km2. Cilj je ovoga rada bio utvrditi ekološke osobine i stanje ihtiofaune ovog poplavnog područja, te rijeke Drave od ušća do 12. rkm kako bi se u budućnosti mogli valorizirati utjecaji revitalizacije bara u zaobalju. Uzorkovano je 1130 jedinki iz 29 vrsta, odnosno 10 porodica. Po broju vrsta najzastupljenija je porodica Cyprinidae. Nadalje 43% ulovljenih jedinki pripadalo je u sedam utvrđenih alohtonih vrsta. Ukupno gledajući najbrojnija je alohtona babuška, Carassius gibelio s 232 jedinke.

Drava, u zadnje vrijeme nazivana hrvatskom Amazonom, je u prošlom i ovom stoljeću pretrpjela značajne regulacijske promjene vodotoka, a napose u pogledu utvrđivanja obala i kanaliziranja vodotoka izgradnjom pera. Ti su zahvati doveli do toga da u poplavnoj nizini ove rijeke ima sve manje funkcionalnih mrtvaja i rukavaca, koji su izuzetno značajni za brojnost ihtiofaune. Osim toga rukavci i mrtvaje su izuzetno značajni za mrijest riba. Bez smišljenih intervencija čovjeka budućnost ovih vodenih površina je zamočvarenje. Alternativa gubljenju mrijesnih površina je revitalizacija. U zadnje vrijeme smišlja se čišćenje i revitalizacija kanalske mreže u predjelu Aljmaškog rita, a prva je kroz proces prošla Stara Drava kod Sarvaša. Cilj je ovoga rada bio utvrditi stanje ihtiofaune poplavnog područja Drave od ušća do 12. rkm te same rijeke na navedenom koridoru kako bi se u budućnosti mogli valorizirati utjecaji revitalizacije kanalske mreže i bara u zaobalju. Tijekom višekratnog istraživanja 2011. godine, u razdoblju od 9. do 12. travnja, obavljeno je uzorkovanje riba pomoću leđnog (baterijskog) i benzinskog elektroagregata te mrežom na 11 lokaliteta od kojih su 7 bili u desnom zaobalju rijeke, a 4 uz desnu obalu glavnog toka. Ukupno je ulovljeno 1144 jedinki koje su pripadale u 33 vrste iz 10 porodica. Po broju vrsta najzastupljenija je, očekivano, porodica Cyprinidae s 15 vrsta, a slijede Gobiidae i Percidae. Od 1144 ulovljene jedinke, 38% pripadalo je u 5 utvrđenih alohtonih vrsta. Ukupno gledajući, najbrojnija vrsta, ujedno i alohtona, je srebrni karas (babuška), (Carassius gibelio), s 232 jedinke. Našim istraživanjem je utvrđeno bolje stanje ihtiofaune bara poplavnog područja negoli sustava tekućice gledamo li veći broj vrsta u barama (27 vs. 23), ali i veću brojnost jedinki (785 vs. 359). Na osnovu izračunatog koeficijenta korelacije nije utvrđena povezanost u sastavu ihtiofaune cjelokupnog lotičkog i lentičkog sustava (R=0.3, p>0.05).