Repository of the Department of Marine Studies at the University of Split
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The most common viral diseases in cage fish farming
No full textU završnom radu opisana je važnost i utjecaj virusnih infekcija na uzgoj riba u kavezima. Detaljno je opisano šest najčešćih virusnih bolesti koje mogu ozbiljno utjecati na zdravlje i produktivnost riba u kaveznom uzgojnom sustavu: infektivna anemija lososa, virusna hemoragijska septikemija, encefalitis, sindrom čiravosti bakalara, limfocistis i virusna nekroza živaca/virusna encefalopatija i retinopatija. Za navedene bolesti analizirani su simptomi, patogeneza, i posljedice na populacije riba. Prevencija i kontrola virusnih bolesti uključuje implementaciju sigurnosnih mjera poput karantene, dezinfekciju opreme i poboljšanu upravljačku praksu. Cijepljenje, kad je dostupno, ima važnu ulogu u suzbijanju bolesti. Zaključno, završni rad ukazuje na važnost praćenja zdravlja riba, osiguravanje preventivnih mjera i razvoj novih terapija i cjepiva kako bi se smanjio utjecaj virusnih bolesti na kavezni uzgoj riba.The thesis describes the significance and impact of viral infections on cage fish farming. It also describes the six most common viral diseases that can significantly affect the health and productivity of fish in cage systems. Among the viral diseases, the following are described in detail: Infectious salmon anaemia, Viral haemorrhagic septicaemia, Encephalitis, Ulcerative dermal necrosis syndrome, Lymphocystis, and Viral nervous necrosis (VNN)/Viral encephalopathy and retinopathy (VER). For these diseases, the symptoms, pathogenesis and consequences for the fish populations are analysed. Prevention and control of viral diseases includes safety measures such as quarantine of new fish, disinfection of equipment and improved management practices. Vaccination, where available, also plays an important role in disease containment. This bachelor thesis emphasises the importance of monitoring fish health, ensuring preventative measures and developing new therapies and vaccines to reduce the impact of viral diseases on cage fish farming
Microplastics in sediments below shellfish farms
No full textU ovom su diplomskom radu predstavljeni rezultati istraživanja prisutnosti mikroplastike u sedimentima ispod uzgajališta školjkaša u blizini Šibenskog mosta. Analizirano je 12 uzoraka sedimenta uzorkovanih na dvije postaje (postaji ispod uzgajališta školjkaša i kontrolnoj postaji) te su prebrojena i zabilježena vlakana i fragmenti mikroplastike. Rezultati su pokazali veći ukupni broj vlakana i fragmenata mikroplastike u sedimentu ispod uzgajališta školjkaša, u odnosu na referentnu postaju. Prikazani rezultati ističu potrebu za kontinuiranim praćenjem mikroplastike u morskim sedimentima te primjenu mjera za smanjenje njenog unosa u okoliš, kako bi se očuvali morski resursi i smanjili rizici za ljudsko zdravlje.This master thesis presents the results of research on the presence of microplastics in the sediments under the shellfish farm near the Šibenik bridge. 12 sediment samples sampled at two stations (station below the shellfish farm and control station) were analyzed and fibers and fragments of microplastics were counted and recorded. The results showed a higher total number of fibers and microplastic fragments in the sediment below the shellfish farm, compared to the reference station. The presented results highlight the need for continuous monitoring of microplastics in marine sediments and the application of measures to reduce their introduction into the environment, in order to preserve marine resources and reduce risks to human health
Climate changes impact on shark migrations
No full textOvim radom detaljnije je obrađena tema migracija morskih pasa koje su uzrokovane povećanjem površinske temperature mora. Ova visoko migratorna skupina morskih organizama, unatoč svojim evolucijskim prilagodbama, našla se u nezavidnoj situaciji gdje postoji potreba za pronalaskom novih staništa. U ovome radu pobliže će biti razrađena obilježja morskih pasa, promjene koja njihova tijela doživljaju promjenom temperature, ali i važnost koju morski psi imaju u morskim ekosustavima.This paper provides a detailed examination of the migration of sharks caused by the increase in sea surface temperature. Despite their evolutionary adaptations, this highly migratory group of marine organisms has found itself in a situation where there is a need to find new habitats. This work will explore the characteristics of sharks, the changes their bodies undergo due to temperature fluctuations, and the important role sharks play in marine ecosystems
Reproductive potential of the sardine during it's spawning season
No full textReproduktivni potencijal srdele (Sardina pilchardus) tijekom sezone mriještenja u Jadranskom moru pokazuje značajne sezonske i biološke varijacije. U istraživanju provedenom u razdoblju od listopada 2023. do travnja 2024. analizirano je 1085 jedinki srdele s rasponom duljine od 11,3 do 17 cm (srednjak ± SD; 13,37 cm ± 0,923 cm) ulovljene plivaricom „srdelarom“. Zabilježeno je 309 mužjaka (39,3 %) i 478 ženki (60,7 %) gdje je ♀/♂ = 0,61. Vrijednosti gonadosomatskog indeksa (GSI) i mase gonada (Wg) vrhunac dostižu u prosincu i ožujku, te progresivno opadaju nakon razdoblja mrijesta. Dijametri oocita mjereni su za sve mjesece istraživanja, te su rane primarne oocite iz stadija I bile prosječne veličine od 61μm, stadij II (primarne oocite) 168 μm, stadij III (sekundarne oocite) 202 μm, dok su tercijarne iz stadija IV bile prosječno 329 μm. Na svim histološkim preparatima utvrđeno je prisustvo postovulatornih folikula (POF), a na temelju zastupljenosti istih odredila učestalost mriještenja koja je iznosila 2,5 dana.The reproductive potential of the European pilchard (Sardina pilchardus) during the spawning season in the Adriatic Sea exhibits significant seasonal and biological variations. In a study conducted from October 2023 to April 2024, 1085 specimens of sardine, ranging in length from 11,3 to 17 cm (mean ± SD; 13.37 cm ± 0.923 cm), caught using a purse seine fishing method specifically targeting sardines, were analyzed. A total of 309 males (39.3%) and 478 females (60.7%) were recorded, with a female-to-male ratio (♀/♂) of 0.61. The values of gonadosomatic index (GSI) and gonad weight (Wg) peaked in December and March and progressively declined after the spawning period. Oocyte diameters were measured for all studied months: early primary oocytes from stage I had an average size of 61 μm, stage II (primary oocytes) averaged 168 μm, stage III (secondary oocytes) averaged 202 μm, and tertiary oocytes from stage IV averaged 329 μm. Overview of all histological preparations revealed the presence of post-ovulatory follicles (POFs), and according to their frequency of occurence the spawning frequency was determined at 2.5 days
The settlement of oyster larvae on collectors in the southern Adriatic
No full textU svrhu praćenja prihvata ličinaka kamenice, Ostrea edulis, zajedno s drugim školjkašima u vodenom stupcu postavljeni su kolektori napravljeni od mreža, pergolara. Eksperimentalno istraživanje provedeno je u uvali Bistrina koja pripada području južnog Jadrana. Kolektori za prihvat su se postavljali dva puta tijekom 2023., a cjelokupno istraživanje in situ je trajalo osam mjeseci. Obzirom na neparametrijsku strukturu podataka korištena je Kruskal-Wallis ANOVA kako bi se ustanovila statistička značajnost između brojnosti prihvaćenih školjkaša. Rezultati pokazuju statistički značajnu razliku (p < 0,05) između prihvata europske plosnate kamenice u usporedbi s prihvatom drugih školjkaša. Veća stopa prihvata O. edulis uglavnom je uočena na dubinama od četiri, pet i šest metara, dok se dagnja, Mytilus galloprovincialis, smjestila u gornjem sloju vodenog stupca tj. u prva tri metra dubine. Tijekom drugog uzrokovanja na kolektorima su dominirale dagnje. Rezultati ukazuju da je ovaj tip kolektora pogodan za prihvat mlađi O. edulis u južnom Jadranu.In order to study the settlement of Ostrea edulis together with other bivalves, collectors made from mussel socks were placed in the water column. This experimental study was carried out in the Bay of Bistrina, in the southern Adriatic. The research lasted eight months, in situ, which included two placements of the collectors in this part of the Bistrina Bay. Due to the non-parametric nature of the data, Kruskal-Wallis ANOVA was used to investigate the significance of differences in the abundance of colonised mussels. The results showed significant differences (p<0.05) between the abundance of settled oysters compared to other bivalves. The higher recruitment rate of O. edulis mainly occurred at depths of 4, 5 and 6 meters, while the mussel Mytilus galloprovincialis settled in the upper layer of the water column i.e., within the first three meters of depth. In the second sampling, mussels dominated on the collectors. The results show that this type of collector is suitable for collecting juveniles of O. edulis in the southern Adriatic
Morphology of saccular otoliths of juvenile and adult Scorpaena porcus (Linnaeus, 1758) in the eastern Adriatic
No full textU ovom radu analizirano je ukupno 89 jedinki vrste Scorpaena porcus (Linnaeus, 1758) s područja istočnog Jadrana. Otoliti vrste S. porcus su uglavnom duguljastog oblika s nazubljenim rubovima, a razlika između otolita odraslih i nedoraslih jedinki vidi se u razvijenosti antirostruma. Ukupna dužina tijela (Lt) svih jedinki se nalazila u rasponu od 3,7 do 24,5 cm, a raspon mase (W) varirao je od 0,78 do 310 g. Dužinsko-maseni odnos opisan je jednadžbom: W = 0,014 x Lt 3.124. Veze između morfometrijskih parametara tijela jedinki (dužina, masa) i parametara otolita (dužina, masa, debljina, širina) opisane su nelinearnim modelom, a masa otolita se pokazala kao najbolji prediktor ukupne dužine tijela kod odraslih jedinki, dok je kod nedoraslih jedinki to bila debljina otolita.In this study, a total of 89 individuals of Scorpaena porcus (Linnaeus, 1758) from the Eastern Adriatic were analyzed. Otoliths of S. porcus are predominantly elongated with serrated edges, and differences between otoliths of adult and juvenile individuals manifest in the development of the antirostrum. The total body length (TL) ranged from 3.7 to 24.5 cm, with a corresponding weight (W) range of 0.78 to 310 g. The length-weight relationship was described by the equation: W = 0.014 x TL 3.124. Relationships between morphometric parameters of the fish (length, weight) and otolith parameters (length, weight, thickness, width) were modelled using nonlinear models. Otolith weight emerged as the best predictor of total length in adult individuals, while in juveniles, otolith thickness was the best primary predictor
The microbiome of farmed mussel Mytilus galloprovincialis in the estuary of Krka river
No full textMytilus galloprovincialis, mediteranska dagnja, je školjkaš velikog ekonomskog i ekološkog značaja, a poznavanje mikrobioma ove vrste važno je za razumijevanje njene fiziologije i zdravlja u različitim uvjetima u svrhu biomonitoringa i predviđanja reakcije na klimatske promjene. Hraneći se metodom filtracije, dagnje u organizmu akumuliraju mikrobne organizme iz okoliša u kojem žive zbog čega oni čine integralni dio fiziologije dagnji i mogu utjecati na razvoj otpornosti na patogene, poboljšanje imunoloških reakcija, detoksikacijskih mehanizama, ali mogu biti i izvori bolesti. U ovom istraživanju ukupna mikrobna zajednica u uzorcima tkiva (škrge i hepatopankreasa) dagnji i mora na uzgajalištu u ušću rijeke Krke tijekom 2022./2023. godine je analizirana metodom DNA metabarkodiranja, korištenjem V4-V5 varijabile regije gena 16S rRNA. Bioinformatičkom obradom dobivenih podataka u tkivima je uočena najveća zastupljenost Proteobacteria, Bacteroidota te Firmacutes sa značajnim razlikama u odnosu na godišnja doba kada su uzorci prikupljani. Od ukupno 648 identificiranih rodova, 522 su zabilježena u škrgama, 516 u hepatopankreasu i 498 u moru, a od toga se 331 rod pojavljuje se u sva tri tipa uzoraka. Od predstavnika rodova koji uključuju patogene organizme, zabilježen je Vibrio, Clostridium, te skupina označena kao Escherichia-Shigella, ali s vrlo niskom zastupljenošću i uvijek u uzorcima hepatopankreasa. Najveća alfa raznolikost je zabilježena za uzorke mora, a manja za škrge i hepatopankreas, a prema sastavu zajednice uzorci morske vode bili su najhomogenija skupina.Mytilus galloprovincialis, Mediterranean mussel, is a shellfish species of great economic and ecological importance, and knowledge about the microbiome of this species is important for understanding its physiology and health in different conditions for the purpose of biomonitoring and predicting the response to climate change. As filter feeders, mussels accumulate microbial organisms from the environment, making them an integral part of mussel physiology and can endow the host with a set of functions like resistance to pathogens, improvement of immune response, detoxification mechanisms, but can also be sources of disease. In this research, the total microbial community in tissues (gills and hepatopancreas) of farmed mussels and marine water of the Krka River estuary during 2022/2023. was analyzed by DNA metabarcoding method, using the V4-V5 variable region of the 16S rRNA gene. The bioinformatic analyses of the obtained data revealed the greatest abundance of Proteobacteria, Bacteroidota and Firmacutes in tissues with significant seasonal differences. Out of a total of 648 identified genera, 522 were recorded in gills, 516 in hepatopancreas and 498 in the sea, and of these 331 genera appeared in all three types of samples. Of the genera that include pathogenic organisms, Vibrio, Clostridium, and a group designated as Escherichia-Shigella were recorded, but with very low abundance and always in hepatopancreas. The highest alpha diversity was recorded for water samples, and the lowest for gills and hepatopancreas, on the other hand according to community composition, seawater samples were the most homogeneous group
POPULATION DYNAMICS OF THE Lepidorhombus boscii (Risso, 1810) IN THE ADRIATIC SEA
No full textU ovom radu predstavljeni su rezultati istraživanja vrste patarače crnopjege, Lepidorhombus boscii (Risso, 1810), na području sjevernog i srednjeg Jadrana. Dio uzoraka je prikupljen tijekom višegodišnjih istraživanja ekspedicije MEDITS u zoni GSA 17 (N=27720), a dio tijekom jednogodišnjeg mjesečnog uzorkovanja na području srednjeg Jadrana (N= 1070). Rezultati istraživanja pokazuju da L. boscii u zoni GSA 17 obitava na dubinama od 61 do 659 m. Omjer spolova je bio 1:0,89 (ž/m). Biometrijska analiza je pokazala statistički značajne razlike u odnosu dužine prsne peraje i standardne dužine tijela, u broju kralježaka između mužjaka i ženki te u broju šipčica trbušne peraje. Dužinsko-maseni odnos ukupnog uzorka je pokazao pozitivno alometrijski rast (b=3,29). Prosječna vrijednost indeksa kondicije ukupnog uzorka iznosi 0,681. Rast populacije je opisan von Bertalanffyevom jednadžbom rasta (L∞=39,63 cm; k=0,10; t0=-4,09). Starost jedinki je određena očitavanjem zona prirasta sagitalnih otolita. U uzorku su najbrojnije bile jedinke starosti dvije i tri godine. Najstarija analizirana ženka je imala 10 godina, a najstariji mužjak 6 godina. Utvrđeno je da je ribolovna smrtnost (F=0,15) veća od prirodne smrtnosti (M=0,11). Kemijskom analizom je detektiran veliki broj metala i organskih spojeva u otolitima. Rendgenskom difrakcijom je određena kristalna struktura otolita; otoliti pravilne morfologije građeni su od aragonita, a oni nepravilne morfologije od kalcita. Intenzitet hranjenja je bio najveći u proljeće, a najzastupljeniji plijen su rakovi, glavonošci i ribe. Ženke postaju spolno zrele pri dužini od Lt50%=19,2 cm, odnosno pri manjim dužinama tijela u odnosu na mužjake (Lt50%=20,3 cm). Najveće vrijednosti gonadosomatskog indeksa za ženke zabilježene su u ožujku, a za mužjake u studenom. Prosječni fekunditet ženki iznosi 87461 oocita. L. boscii u Jadranskom moru najintenzivnije se razmnožava od studenog do ožujka.This paper presents the results of research on the species of the four-spot megrim, Lepidorhombus boscii (Risso, 1810), in the area of the northern and central Adriatic. Part of the samples were collected during multi-year investigations of the MEDITS expedition in the GSA 17 zone (N=27720), and part during one-year monthly sampling in the area of the central Adriatic (N=1070). The results of the research show that L. boscii lives in the GSA 17 zone at depths from 61 to 659 m. The sex ratio was 1:0,89 (f/m). Biometric analysis showed that there are statistically significant differences in the ratio of the length of the pectoral fin to the standard length of the body, in the number of vertebrae between males and females, and in the number of rays of the ventral fin. The length-weight relationship of the total sample showed positive allometric growth (b=3,29). The average value of the condition factor of the total sample was 0,681. Population growth is described by the von Bertalanffy growth equation (L∞=39,63 cm; k=0,10; t0=-4,09). Age was determined by reading the growth zones of the sagittal otoliths. The most numerous in the sample were specimens aged two and three years. The oldest female was 10 years old and the oldest male was 6 years old. Fishing mortality (F=0,15) of this species were higher than natural mortality values (M=0,11). Large number of metals and organic compounds were detected by chemical analysis of otoliths. The crystal structure of the otolith was determined by the X-ray diffraction; otoliths of regular morphology are composed of aragonite and those with irregular morphology of calcite. The intensity of feeding was the highest in spring, and the most abundant prey are crustaceans, cephalopods and fish. Females reached maturity (Lt=19,2 cm) at smaller lengths than males (Lt=20,3 cm). The highest values of the gonadosomatic index for females were recorded in March, and for males in November. The average fecundity of females is 87461 oocytes. L. boscii reproduces most intensively in the Adriatic Sea from November to March
Bioinvasion of the blue crab Callinectes sapidus in the Adriatic
No full textPlavi rak Callinectes sapidus Rathbun, 1896 je gospodarski i ekološki važna vrsta nativna na području zapadnog Atlantskog oceana. Danas je plavi rak poznat kao veoma uspješna invazivna strana vrsta zbog brze stope rasta, visokog fekunditeta i značajne tolerancije na ekstremne uvjeta okoliša. Kao značajna invazivna vrsta predstavlja problem prirodnoj ravnoteži svih novo naseljenih staništa koje uključuju i Jadransko more te traži dodatni monitoring u svrhu zaštite autohtone faune i iskorištavanju mogućih gospodarskih značajki u skoroj budućnosti. U ovom radu su opisane biološke značajke plavog raka, s naglaskom na životni ciklus, te je detaljno prikazan povijesni pregled širenja raka u europskim vodama i Jadranskom moru.A native of the western Atlantic Ocean, the blue crab Callinectes sapidus Rathbun, 1896 is significant both economically and ecologically. The blue crab's fast growth, high fecundity, and remarkable resistance to harsh environmental conditions have earned it a reputation as an extremely effective invasive alien species today. Being a significant invasive species, it threatens the natural balance in all newly invaded habitats, including the Adriatic Sea. As such, it needs to be closely monitored to preserve the local wildlife and take advantage of any future potential economic benefits. The biological characteristics of the blue crab are discussed in this study, with a focus on the life cycle. A thorough historical account of the crab's expansion throughout European waters and the Adriatic Sea is also provided
Genome characteristics of common octopus Octopus vulgaris (Cuvier, 1797)
No full textU ovom završnom radu opisane su osnovne značajke obične hobotnice Octopus vulgaris, njezin gospodarski značaj u ribarstvu i akvakulturi, te značaj kao modela u neurobiologiji. Kako bi se istražila i razumjela fiziologija ovih naprednih organizama na staničnoj razini kao i regulacijske molekularne mreže, potrebno je imati dobre nacrte genoma sastavljene na razini kromosoma. U gospodarskom kontekstu, što bolji nacrt genoma omogućava i razvoj buduće akvakulture i specijaliziranih programa selekcije. Trenutno glavni pristup sastavljanju genoma uključuje kombiniranje kratkih i dugih nukleotidnih sljedova visoke pokrivenosti koji se dobivaju metodama naprednog sekvenciranja, kao i informacije o kromosomskoj konformaciji. Prvi nacrt genoma na razini kromosoma vrste O. vulgaris je objavljen 2023. godine i ima ukupno 2,8 Gb, N50 = 118,9 Mb, N90 = 18,2 Mb, i cjelovitost je na jako dobroj razini (BUSCO indeks: C:92,3% (S:91,8%, D:0,5%), F:2,7%, M:5,0%). Genom hobotnice ima 30 kromosoma (1n = 30). Ukupno je pronađeno 23.423 gena koji kodiraju proteine, sadrže u prosjeku 8,42 egzona, a identificirano je i 1849 dugih nekodirajućih RNA. Danas je uslijed razvoja naprednih metoda sekvenciranja i komputacijskih algoritama omogućeno relativno brzo dobivanje kvalitetnih genoma i za nemodelne vrste, te to predstavlja temelj za podizanje ekoloških i evolucijskih studija na cjelogenomsku razinu.This disertation describes the basic features of the common octopus Octopus vulgaris, its economic importance in fisheries and aquaculture, and its importance as a model in neurobiology. In order to investigate and understand the physiology of these advanced organisms at the cellular level, as well as the regulatory molecular networks, it is necessary to build good quality chromosome level genome assemblies. In the economic context, good quality genomes enable the development of future aquaculture practices and specialized selection programs. Currently, the main approach to genome assembly involves combining high-coverage short and long nucleotide sequences obtained by next-generation sequencing methods, as well as information on chromosomal conformation. The first chromosome level genome assemblie of O. vulgaris was published in 2023 and has a total of 2.8 Gb, N50 = 118.9 Mb, N90 = 18.2 Mb, with very satisfactory completeness level (BUSCO index: C: 92.3% (S:91.8%, D:0.5%), F:2.7%, M:5.0%). The octopus genome has 30 chromosomes (1n = 30). A total of 23,423 protein-coding genes were found, containing an average of 8.42 exons, and 1,849 long non-coding RNAs were also identified. Today, due to the development of next-generation sequencing methods and computational algorithms, it is possible to obtain relatively good quality genome drafts even for non-model species, and this represents the basis for performing ecological and evolutionary studies at the whole-genome level