The southwest shore of the island of Dugi Otok is characterized by the unusual sample occurrence of Mn-hydrated oxide mineralization in the form of botryoidally and globular, fine-laminated ...concentric aggregates, crusting the Upper Cretaceous backshore limestones. The mineralization consists mainly of Fe impoverished 10-Å tecto-manganate todorokite (enriched in Mg and transition metals) accompanied by accessory MnO·OH. Todorokite chemical composition is typical of a hydrogenous origin in an oxic shallow marine environment. According to our model, Mn has been recurrently leached and mobilized from the Late Pleistocene sea floor sediments located around 50 nautical miles south of Dugi Otok. We propose a link between the Mn-geochemical anomaly of these sediments and the alteration of distinct, spatial close pre-Holocene tephra, dispersed over the entire recent Adriatic area.
Na jugozapadnoj obali Dugog otoka prema otvorenom moru u zoni plime i oseke postoji neobična i obilna pojava mineralizacije manganom u formi hidratiziranih oksida. Javlja se kao ovojnica, kora, tanka presvlaka, odnosno kao grozdasti fino laminirani, koncentrični agregat na gornjokrednim vapnencima i dolomitima. Mineralizaciju čine željezom osiromašeni 10-Å tekto-manganati s prevladavajućim todorokitom. Kemijski sastav todorokita ukazuje na hidrogenetsko podrijetlo u oksičnom okolišu plitkog mora. Držimo da je mangan potrebit za mineralizaciju izlužen i mobiliziran iz pridnenih sedimenata smještenih nekih 50 nautičkih milja južno od mjesta mineralizacije. Mangan je bio izvorno vezan u prhkim piroklastičnim naslagama raspršenim vulkanskim erupcijama iz flegrejskih polja pored Napulja po cijelom jadranskom području neposredno pred početak holocena.
Temperate Labrid species are nest builders with nests usually made out of plant material or detritus.During the summer of 2004, 131 nests of three wrasses (Symphodus roissali, S. ocellatus and ...S.cinereus) were studied by SCUBA diving in the Slovenian coastal sea (northern Adriatic) in orderto compare nest parameters and microhabitat preferences among the species. For the descriptionof the structure of each nest, algal species, benthic invertebrates and type of substrata within thenest were determined, as well as the features of each microhabitat. A Redundancy Analysis (RDA)was performed in order to highlight the distribution of the three species in relation to environmentalvariables and their preferences for different biotic and abiotic variables in the construction of nests.Labrid species were found to be more abundant on rocky bottoms, where the Cystoseiretum barbataeassociation is dominant. It seems that the studied species show a preference for some microhabitats,although are building their nests using the most abundant algal material in the environment. OnlyS. ocellatus seems to select shrub-forming algae as the main nest-forming material.
Usnjače umjereno toplih mora su graditelji gnijezda koja su najčešće izgrađena od biljnog materijalaili detritusa. Tijekom ljeta 2004. godine, 131 gnijezdo triju vrsta usnjača (Symphodus roissali,S. ocellatus i S. cinereus) je istraživano pomoću SCUBA ronjenja u slovenskim priobalnim vodama(sjeverni Jadran) sa svrhom uporedbe parametara gnijezda i sklonosti prema mikrostaništima unutarvrsta. Za opise strukture svakog gnijezda, određivane su vrste algi, bentoski beskralješnjaci itipovi substrata unutar gnijezda, isto kao i odlike svakog mikrostaništa. RDA analiza je korištena sasvrhom da se rasvijetle saznanja o raspodjeli svake vrste u odnosu na kolebljive parametre okoliša injihove sklonosti prema različitim biotičkim i abiotičkim sadržajima u izgradnji gnijezda. Ove vrsteusnjača su znatno brojnije na kamenitim dnima, gdje asocijacija Cystoseiretum barbatae prevladava.Izgleda da istraživane vrste pokazuju određene sklonosti prema nekim mikrostaništima, ali gradesvoja gnijezda koristeći najbrojnije alge koje se mogu zateći u okolišu. Samo S. ocellatus izgledaodabire grmolike alge kao glavni materijal za izgradnju gnijezda.
The reproduction of the karamote prawn, Penaeus (Melicertus) kerathurus (Forskål 1775), was studied for the native population in Amvrakikos Gulf (Ionian Sea; western Greece). Sampling was carried out ...on a monthly basis between June 1999 and May 2001. The results showed that the shrimp Penaeus (Melicertus) kerathurus reproduction period spans between late April and late September. The size-at-maturity was estimated at a size of 45.23 mm carapace length (or 156.2 mm in total length). The smallest mature female in the samples was found to have 30 mm CL or 113.95 mm TL. Maximum gonadosomatic index (GSI) was estimated to be 9.62% for female shrimps at stage IV gonad maturity stage. The population gonadosomatic index peaks in May with an average value of 6.895%. Potential fecundity was estimated to be 154600 of oocytes per g of gonad tissue at the stage IV (mature female). Monthly sex ratios (males/females) were found greater than 1 throughout the year with maximum values reaching 2.5. A new life cycle pattern is proposed for this particular population.
Razmnožavanje kozice, Penaeus (Melicertus) kerathurus (Forskål, 1775), je istraživano na populacijama iz prirodne sredine na području zaljeva Amvrakikos (Jonsko more, zapadna Grčka). Uzorkovanje je obavljeno svakog mjeseca u razdoblju između lipnja 1999. godine i svibnja 2001. godine. Rezultati istraživanja pokazuju da se kozica mrijesti u razdoblju travanj-rujan. Veličina pri kojoj kozica dosiže spolnu zrelost iznosi 45.23 mm dužina karapaksa (156.2 mm ukupna dužina). Utvrđena je najmanja spolno zrela ženka u uzorku pri dužini 30 mm dužina karapaksa (113.95 mm ukupna dužina). Najveća izračunata vrijednost gonadosomatskog indeksa iznosi 9.62% za ženke pri stadiju IV zrelosti gonada. Gonadosomatski indeks za čitavu populaciju ima svoj maksimum u svibnju pri srednjoj vrijednosti od 6.895%. Izračunati potencijalni fekunditet iznosi 154600 oocita po gramu tkiva gonada pri stadiju IV (zrela ženka). Mjesečni omjer spolova (mužjak/ženka) ima vrijednosti veće od 1 tijekom cijele godine uz maksimalnu vrijednost 2.5. Iznesen je i predložak obrasca novog životnog ciklusa populacije na istraživanom području.
Zooplanktonska zajednica je istraživana u travnju 2006. na devet postaja duž i ispred visokostratificiranog estuarija rijeke Krke, uporabom dviju planktonskih mreža Nansen tipa, opremljenih svilama ...finoće tkanja 53- i 125-μm. Tintinidi, kopepodni rakovi i njihovi razvojni stadiji te ličinke mekušaca su dominirale u zooplanktonu, a zabilježeno je 28 vrsta tintinida i 41 vrsta kopepoda. Kod tintinida i kopepoda zamijećen je pad brojnosti i porast broja vrsta prema ušću estuarija, uz izraženu dominaciju estuarsko-neritičkih vrsta. Najbrojniji tintinidi su bili Tintinnopsis campanula i Favella ehrenbergii. Mali ciklopoidni kopepod Oithona nana dominirao je u gornjem dijelu estuarija, vjerovatno se hraneći organskom tvari nakupljenoj na permanentnoj haloklini. Udio kalanoidnih kopepoda se povećavao prema postajama iza ušća, s iznimkom eutrofiziranog područja šibenske luke na kojem su ponovo zabilježene visoke brojnosti ciklopoida Oithona nana. Usporedba brojčanih podataka iz korištenih planktonskih mreža i sastav populacije zooplanktona ukazuju da bi kombinacija 125-μm planktonske mreže i Niskin crpca dala optimalne podatke o ekologiji zooplanktonske zajednice tijekom budućih istraživanja ovog i sličnih visokostratificiranih estuarija.
The zooplankton assemblage was investigated in April 2006 at 9 stations along, and in front of, the highly stratified salt-wedge Krka river estuary, using 53- and 125-μm mesh Nansen nets. Tintinnids, copepods and their developmental stages and mollusc larvae dominated the zooplankton community, with 28 tintinnid and 41 copepod taxa recorded in the investigated area. Both tintinnid and copepod communities showed a general decrease in abundance and increase in species number from the head to the mouth of estuary, with a clear dominance of estuarine-neritic species. The most abundant tintinnids were Tintinnopsis campanula and Favella ehrenbergii. Small cyclopoid copepod Oithona nana dominated in the upper reaches, presumably feeding opportunistically on abundant organic matter accumulated at the permanent halocline. The contribution of calanoids intensified towards marine stations, except in the eutrophicated Šibenik harbour area in the middle reaches, where cyclopoid Oithona nana again proliferated. An assessment of the sampling performances of the 53- and 125-μm nets and data on zooplankton population structure indicated that the 125-μm mesh size plankton net in combination with Niskin bottles would give the optimal insight into the ecology of all zooplankton components in future investigations of this and similar highly stratified estuaries.
A study on dredge catches has been carried out for the first time in the eastern part of the Adriatic Sea. The paper describes the dredge used (known locally as rampon) and presents its selectivity ...toward the primary catch, the pilgrim's scallop (Pecten jacobaeus, Pectinidae, Mollusca). The population of P. jacobaeus in the area available for the dredge operation was found not to be endangered at present, so harvesting ca be continued with the present intensity
The population dynamics of the juvenile anchovy Engraulis encrasicolus (N equal to 2,564) was studied using monthly length and weight frequency data (August 1989 - March 1991) from the central part ...of the Adriatic Sea (Novigrad Sea and Karin Sea). The Von Bertalanffy growth parameters were estimated as L approximately equal to 13.2 cm total length, K equal to 0.82 per year and t0 equal to -0.5. Mortality rates for all fish, estimated from a length converted catch curve were as follows: total mortality was Z equal to 1.664 per year, fishing mortality F equal to 0.230 per year, with natural mortality M equal to 1.430 per year derived from Pauly's empirical formula. Exploitation rate was E equal to 0.139. Fifty per cent maturity was reached at 9.0 cm total length.
This paper is an overview of marine aquaculture in Croatia and an in-depth coverage of works and achievements of scientists in the Laboratory of Marine Aquaculture. At the end of the 80's the first ...steps into the field of fish genetics were made by working on hybrids of Sparus aurata x Diplodus puntazzo, Sparus aurata x Diplodus vulgaris and finally Dentex dentex x Diplodus sargus; the last cross was found to be potentially interesting for marine aquaculture. Further research on chromosome manipulation was conducted to induce triploidy of Sparus aurata by temperature shocking freshly fertilized eggs. At the beginning of the 90's research on population genetics of mussel (Mytilus galloprovincialis) was conducted in the Laboratory in co-operation with French colleagues from IFREMER. The present work includes research on chromosome structure of Sparid species from the Eastern Adriatic as well as population genetics. In the future, will be implemented a database on Adriatic fish, mainly with the goal to support a program of protection of wild populations of finfish.
The recruitment of leaping grey mullet, Liza saliens juveniles in the Neretva River estuary (middle eastern Adriatic Sea, Croatia) started in July, was highest in August, decreased in September, and ...was unobserved later. The juveniles firstly occupied mouths of rivers and channels and then started migrating to more freshwater habitats. By feeding investigation, the harpacticoid copepods were the dominant prey in the stomachs of L. saliens juveniles during the period from August to December and nematodes replaced those as the dominant prey from January to April. Plant material in the stomachs started to appear at 24 mm of standard length, and was common prey in fish larger than 26 mm. In comparison with other Adriatic mullet’s species, the leaping grey mullet juveniles first started to recruit during July and August, while other grey mullet species appeared later (in September) in the Neretva River estuary. Such intraspecies spawning and recruitment segregation together with the optimal quantity and quality of available and preferable prey could provide an explanation for the recent success and propagation of this species in this area.
Novačenje mlađi cipla dugaša, Liza saliens na području estuarija rijeke Neretve počinje u srpnju, najveće je u kolovozu, smanjuje se u rujnu, nakon čega nije zabilježeno. Mlađ se najprije pojavljuje na ušćima rijeka i kanala, a zatim počinje migrirati prema vodama niže slanosti. U prehrani mlađi cipla dugaša od kolovoza do prosinca su dominirali harpatikoidni kopepodi, a od siječnja do travnja oblići. Biljni materijal se počinje pojavljivati u probavilima jedinki najmanje ukupne dužine 24 mm, a uobičajen je u probavilima riba većih od 26 mm. Uspoređujući s ostalim vrstama cipala u području estuarija rijeke Neretve koje se mrijeste u ljetno-jesenskom razdoblju, dugaš se počinje novačiti prvi, tijekom srpnja i kolovoza, dok se ostale vrste pojavljuju u rujnu. Ovo ranije mriještenje i novačenje mlađi bez nazočnosti drugih vrsta cipala, tijekom razdoblja optimalnog sastava i brojnosti hrane, može biti jedan od razloga recentne propagacije cipla dugaša na području estuarija Neretve.
Areas where the Phoenician juniper (Juniperus phoenicea) is very abundant, as well as communities in which this species is dominant, represent a special form of forest community, commonly developed ...as xerothermic macchia known as Pistacio lentisci – Juniperetum phoeniceae and included in the Oleo-Ceratonion alliance. This association represents an important progressive stage in the succession towards evergreen vegetation, developed mostly after forest fires. In this paper, we analysed the floristic characteristics of the Pistacio lentisci – Juniperetum phoeniceae association on the islands of Čiovo, Šolta, Brač, Hvar, Korčula and Lopud, including the peninsula of Pelješac and the Dubrovnik coastal regions (Dubrovačko primorje). In the southern localities this association is still in its initial phase of development, while the Central Dalmatian results indicates a succession of vegetation towards the development of a Querco ilicis – Pinetum halepensis forest community.
Površine na kojima se obilno razvija somina (Juniperus phoenicea), te sastojine u kojima ta vrsta dominira, predstavljaju posebnu šumsku zajednicu razvijenu u obliku kserotermne makije Pistacio lentisci – Juniperetum phoeniceae, priključene svezi Oleo-Ceratonion. Ta asocijacija predstavlja značajan progresijski stadij sukcesije vazdazelene vegetacije, najčešće nakon šumskih požara. U ovome su radu analizirane florističke značajke makije somine na otocima Čiovu, Šolti, Braču, Hvaru, Korčuli i Lopudu, te na poluotoku Pelješcu i u Dubrovačkom primorju. Na području južne Dalmacije ta je asocijacija još u inicijalnoj fazi razvoja, dok rezultati istraživanja na području srednjodalmatinskih otoka ukazuju na sukcesiju vegetacije u smjeru razvitka šumske zajednice Querco ilicis – Pinetum halepensis.
