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Abstract: Although geographically well apart, there are interesting similarities between the ecosystems of the Sea of Marmara and the Adriatic Sea. In this study, following an evaluation of the ecological problems as well as oceanography, productivity, plankton biomass of these seas, macro-jellyfish ecology of the two ecosystems were discussed comparatively. The Sea of Marmara and the Adriatic Sea are among the areas where increases in jellyfish and mucilage events have been observed in recent decades. Environmental problems such as global warming, oxygen depletion, eutrophication, overfishing, intense maritime traffic, and habitat destruction are causing opportunistic and alien species to increase in both abundance and number of species. As biodiversity declines due to habitat destruction, so does the ecosystem’s means and ability to combat the invasion of alien species in both ecosystems. Accordingly, disruption of lower food chains can put pressure on the entire ecosystem and affect socio-ecological prospects. The number of species of Scyphozoa and Ctenophora was found to be higher in the Adraitic Sea compared to the Sea of Marmara. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for Aurelia aurita, Rhizostoma pulmo, Chrysaora hysoscella and non-native Mnemiopsis leidyi in the Marmara Sea. However, although A. aurita and R. pulmo show widespread blooms according to the seasons and regions in the Adriatic Sea, C. hysoscella and M. leidyi produced blooms limited to a few areas. Negative and positive interactions of macrojelyfishes with human were also considered. Semi-enclosed seas such as the Sea of Marmara and the Adriatic Sea are representative of many temperate coastal waters where climate change and anthropogenic stressors are increasing, and the ecosystem has changed from a fish-dominated to a jellyfish-dominated ecosystem.
Keywords: jellyfish, eutrophication, diversity, introduce, fisheries
Published in DiRROS: 07.05.2025; Views: 97; Downloads: 39
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Abstract: Jellyfish blooms have increased in coastal areas around the world and the outbreaks have become longer and more frequent over the past few decades. The Mediterranean Sea is among the heavily affected regions and the common bloom - forming taxa are scyphozoans Aurelia aurita s.l., Pelagia noctiluca, and Rhizostoma pulmo. Jellyfish have few natural predators, therefore their carcasses at the termination of a bloom represent an organic-rich substrate that supports rapid bacterial growth, and may have a large impact on the surrounding environment. The focus of this study was to explore whether jellyfish substrate have an impact on bacterial community phylotype selection. We conducted in situ jellyfish - enrichment experiment with three different jellyfish species. Bacterial dynamic together with nutrients were monitored to assess decaying jellyfish-bacteria dynamics. Our results show that jellyfish biomass is characterized by protein rich organic matter, which is highly bioavailable to ‘jellyfish - associated’ and ‘free - living’ bacteria, and triggers rapid shifts in bacterial population dynamics and composition. Based on 16S rRNA clone libraries and denaturing gradient gel electrophoresis (DGGE) analysis, we observed a rapid shift in community composition from unculturable Alphaproteobacteria to culturable species of Gammaproteobacteria and Flavobacteria. The results of sequence analyses of bacterial isolates and of total bacterial community determined by culture independent genetic analysis showed the dominance of the Pseudoalteromonadaceae and the Vibrionaceae families. Elevated levels of dissolved proteins, dissolved organic and inorganic nutrient release, bacterial abundance and carbon production as well as ammonium concentrations characterized the degradation process. The biochemical composition of jellyfish species may influence changes in the amount of accumulated dissolved organic and inorganic nutrients. Our results can contribute insights into possible changes in bacterial population dynamics and nutrient pathways following jellyfish blooms which have important implications for ecology of coastal waters.
Keywords: sea, medusae, research programmes, DGGE, Pelagia noctiluca, gel electrophoresis, oligotrophic waters, Adriatic Sea, jellyfish, gelatinous zooplankton, bacteria, flavobacteria
Published in DiRROS: 26.03.2025; Views: 172; Downloads: 125
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Abstract: The interdependence between the economy and the environment is becoming a fact of increasing importance. Productive coastal areas have been recognised as one of the most valuable ecosystems from an ecological and socio-economic point of view. In this paper we focus on the massive presence of jellyfish in the northern Adriatic and their effect on the Slovenian economy. Our results indicate that high jellyfish abundance in 2004 resulted in a reduction of fish catch, value added, gross income, and employment in the fishing industry. Moreover, the government and the EU have acknowledged the impact of jellyfish on the fishing industry by allocating financial help to the fishermen involved. We attempted to assess other factors influencing the fishing industry but none were statistically significant. The input-output analysis has not revealed a significant impact on the entire Slovenian economy presumably due to the small contribution of the fishing industry to Slovenian GDP. Our work is a first attempt to relate ecological changes such as jellyfish outbreaks in the northern Adriatic to the wider economy and we suggest that such a methodology can be applied to other countries/regions and to other natural phenomena affecting the economy.
Keywords: morje, objavljeni prispevki na konferenci, morsko ribištvo, trajnostni razvoj, gospodarski aspekti, meduze, množično pojavljanje, distribucija, numerično modeliranje, klimatske spremembe, hipoteze, Pelagia noctiluca, Jadransko morje, gospodarske politike
Published in DiRROS: 26.03.2025; Views: 173; Downloads: 142
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Abstract: Slovenija kot članica programa Združenih narodov za okolje (UNEP) in podpisnica Konvencije o varovanju Sredozemskega morja pred onesnaženjem (Barcelonska konvencija) aktivno sodeluje v programu Sredozemskega akcijskega načrta (MAP-Mediterranean Action Plan). Program Spremljanja stanja okolja (MED POL program) izvajamo s finančno pomočjo Ministrstva za okolje in prostor R Slovenije, Agencije RS za okolje. Poročilo vključuje rezultate mikrobioloških analiz kakovosti kopaliških vod, fizikalno-kemične in biološke analize morske vode za oceno stopnje evtrofikacije, rezultate policikličnih in aromatskih ogljikovodikov, kadmija in živega srebra v sedimentu in morskih organizmih (školjkah), oceno vnosa s kopenskih točkovnih virov onesnaženja v morje in rezultate analiz biomonitoringa za oceno bioloških posledic onesnaženja na morskih organizmih.
Keywords: varstvo narave, kakovost morja, kontrola kakovosti, morje, onesnaževanje, ekologija morja, biomonitoring, monitoring, evtrofikacijski monitoring, indeks trofičnosti, evtrofizacija, trofični indeks, Tržaški zaliv, Barcelonska konvencija, Jadransko morje
Published in DiRROS: 16.09.2024; Views: 1147; Downloads: 656
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Abstract: Deskriptor 1: Biotska raznovrstnost se ohranja. Kakovost in prisotnost habitatov ter razporeditev in številčnost vrst so v skladu s prevladujočimi fiziografskimi, geografskimi in podnebnimi pogoji. »Presojo je treba opraviti na več ekoloških ravneh: na ravni ekosistemov, habitatov (vključno z njimi povezanimi združbami na nivoju biotopov) in vrst, ki so upoštevane v strukturi tega dela ob upoštevanju točke 2 dela A. Za nekatere vidike tega deskriptorja je potrebna dodatna znanstvena in tehnična podpora. Pri obravnavi širšega obsega deskriptorja je treba ob upoštevanju Priloge III k Direktivi 2008/56/ES določiti prioritete med elementi biotske raznovrstnosti (vrste, habitati in ekosistemi). To omogoča prepoznavanje tistih elementov in območij, kjer vplivi in grožnje nastajajo, poleg tega pa podpira opredelitev ustreznih kazalcev med izbranimi merili, primernimi za zadevna območja in elemente biotske raznovrstnosti. Obveznost regionalnega sodelovanja iz členov 5 in 6 Direktive 2008/56/ES je neposredno povezana z izbiro elementov biotske raznovrstnosti znotraj regij, podregij in pododdelkov, kjer je mogoče, pa tudi z vzpostavitvijo referenčnih razmer v skladu s Prilogo IV k Direktivi 2008/56/ES. Modeliranje z uporabo platforme geografskega informacijskega sistema je lahko uporabna podlaga za določanje območja razširjenosti elementov biotske raznovrstnosti ter človekovih dejavnosti in pritiskov zaradi teh dejavnosti, ob upoštevanju, da se vse mogoče zajete napake ustrezno ocenijo in opišejo ob uporabi rezultatov. Ti podatki so pogoj za ekosistemsko upravljanje človekovih dejavnosti in za razvoj s tem povezanih prostorskih orodij.«
Keywords: morje, obalno morje, onesnaževanje morja, plankton, hranilne snovi, ekološki parametri, onesnažila, onesnaževalci, biocenoze, okvirna direktiva o morski strategiji, poročila, onesnaženost, kvaliteta okolja, morska strategija, deskriptorji
Published in DiRROS: 16.09.2024; Views: 1085; Downloads: 745
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