This study combines radiocarbon (14C) analysis and sclerochronology research, an approach that to the best of our knowledge, has not yet been applied using bivalves from the Mediterranean Sea. We ...analyzed shells from the North Adriatic Sea: live- and dead-collected specimens of the infaunal bivalve Glycymeris pilosa and two dead-collected specimens of Glycymeris sp. According to crossdating results, growth increment time series obtained from acetate peels of the dead-collected G. pilosa (S3FP11) indicate the potential for creating longer chronologies from live and dead-collected specimens. The greatest longevity was seen in the dead-collected Glycymeris sp. specimen S3F3, estimated to be ~130 years (started growing AD 1678–1742 and died AD 1826–1860), indicating the potential to extend Glycymeris growth increment chronologies to past centuries. The highest ∆14C values obtained corresponded to the calendar year 1974. The 14C record obtained from G. pilosa correlates well with the modeled surface ocean (mixed-layer) bomb pulse curve (Reimer et al. 2009). Based on the results obtained from the shell growth increment assigned to AD 1950, the reservoir age and reservoir correction (ΔR) are 264±23 years and –6±32 years, respectively.
We analyzed and discussed bathing water quality at 11 official bathing sites in Kaštela (Croatia) in the period 2009-2022. The results showed spatial and temporal variations in quality. The worst ...bathing water quality was in the eastern part of the area, at beaches Torac, Kamp and Gojača. Levels of indicator microorganisms at identified sources of fecal pollution near these beaches indicate a significant load of fecal material to these areas. The observed decrease in annual fecal indicator bacteria exceedances, while not statistically significant, indicates a trend toward improvement in water quality. The number of sites with worse annual and final assessment showed a decreasing trend only since 2017 and 2020, respectively, which is not a ‘sufficient’ time period to draw a clear conclusion about the trend. The improvements are probably the result of intensive work in recent years to improve the sewage system in the area. In the annual and final assessment, bathing sites from Kaštela with ‘poor’ water quality accounted on average for more than 27% of all waters with ‘poor’ quality in Croatia. This implies that additional efforts are needed to eliminate the sources of fecal pollution in the area.
U ovom smo radu analizirali kvalitetu mora za kupanje na 11 službenih plaža u Kaštelima (Hrvatska) u razdoblju 2009.-2022. Rezultati su pokazali prostorne i vremenske varijacije kvalitete. Najlošija kvaliteta mora za kupanje zabilježena je u istočnom dijelu područja, na plažama Torac, Kamp i Gojača. Razine indikatorskih mikroorganizama na utvrđenim izvorima fekalnog onečišćenja u blizini ovih plaža ukazuju na značajno opterećenje fekalnim materijalom u ovim područjima. Iako trend smanjena broja prekoračenja graničnih vrijednosti indikatorskih mikroorganizama tijekom godine nije statistički značajan, ipak upućuje na poboljšanja. Broj lokacija s lošijom godišnjom i konačnom ocjenom pokazuje trend pada tek od 2017. odnosno 2020. godine, što nije dovoljno vremensko razdoblje da bi se moglo jasno zaključiti o trendu. Poboljšanja su vjerojatno rezultat intenzivnog rada na poboljšanju kanalizacijskog sustava na tom području u posljednjih nekoliko godina. U godišnjoj i konačnoj ocjeni, kaštelanske plaže s nezadovoljavajućom kvalitetom mora u prosjeku su činile više od 27% svih plaža nezadovoljavajuće kvalitete u Hrvatskoj. To ukazuje da su potrebni dodatni napori za uklanjanje izvora fekalnog onečišćenja na cijelom području.
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We investigated the effect of intravalvular liquid loss on changes in Escherichia coli (E. coli) levels in mussels (Mytilus galloprovincialis) harvested in different seasons and refrigerated (5°C) ...for 72 hours. A positive effect of seawater temperature at the time of harvesting on intravalvular liquid loss was found. No changes in E. coli levels in mussels (flesh and intravalvular liquid), as the result of intravalvular liquid loss, were observed. Levels of E. coli in the flesh decreased, probably as a result of cells dying off, causing the maintenance of E. coli levels in flesh and intravalvular liquid to be stable throughout storage.
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Fungal flora in coastal/inland beach sand and recreational water is a neglected field of study, despite its potential impact on human health. A joint International Society for Human and Animal ...Mycology/European Confederation for Medical Mycology (ISHAM/ECMM) working group was formed in 2019 with the task to set up a vast international initiative aimed at studying the fungal contamination of beaches and bathing waters. Here we review the importance of the topic, and list the main results and achievements from 12 scientific publications. Fungal contamination exists at different levels, and the genera most frequently found were Aspergillus spp., Candida spp., Fusarium spp., and Cryptococcus spp., both in sand and in water. A site-blind median was found to be 89 colony-forming units of fungi per gram of sand in coastal/inland freshwaters. This threshold has been used for the sand quality criterion of the blue flag in Portugal. Additionally, our data were considered pivotal and therefore used for the first inclusion of fungi as a biological taxon of interest in water quality and sand monitoring recommendations of the World Health Organization's new guidelines on recreational water quality (Vol.1-Chap7). The findings of the consortium also suggest how environmental conditions (climate, salinity, soil pH, nitrogen, etc.) influence microbial communities in different regions, and that yeast species like Candida glabrata, Clavispora lusitaniae, and Meyerozyma guilliermondii have been identified as potential fungal indicators of fecal contamination. Climate change and natural disasters may affect fungal populations in different environments, and because this is still a field of study under exploration, we also propose to depict the future challenges of research and unmet needs.
The Pacific oyster, Crassostrea gigas, was introduced into the Europe in the late 1960s for aquaculture purposes and has since spread extensively in Mediterranean waters. For the first time, ...screening of the four ecologically most suitable bays along the Eastern Adriatic coast was conducted to detect the possible presence of non-native oysters. Sequencing analysis of a fragment of mitochondrial 16S rRNA was examined to demonstrate the presence of the exotic species C. gigas in the natural environments of the northern and central coastal areas of the eastern Adriatic. The likely routes of invasion are discussed and the importance of monitoring the distribution of feral C. gigas populations emphasized, with a focus on the potential direct and indirect effects on the native European flat oyster, Ostrea edulis.Original Abstract: Japanska ili pacificka kamenica, Crassostrea gigas, uvedena je u Europu kasnih 1960-ih za potrebe akvakulture i od tada se intenzivno prosirila po Mediteranu. Po prvi put je izvrsen pregled cetiriju ekoloski najprikladnijih zaljeva istocne obale Jadrana kako bi se utvrdila prisutnost alohtone kamenice. Analiza djelomicnog fragmenta mitohondrijske 16S rRNA je koristena kako bi se molekularno identificirala egzoticna vrsta C. gigas u prirodnim stanistima sjevernih i sredisnjih obalnih podrucja istocnog Jadrana. Moguci invazijski putevi su raspravljani kao i vaznost pracenja distribucije populacija C. gigas, s naglaskom na potencijalne izravne i neizravne ucinke na autohtonu europsku plosnatu kamenicu Ostrea edulis koja obitava u Jadranskom moru.
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The Pacific oyster Crassostrea gigas was introduced for the aquaculture purposes in many different parts of the world. However, the species has never been officially introduced for commercial farming ...in the Croatian part of the Adriatic Sea. Interestingly, in the 1970s, the Pacific oyster has been reported in the natural habitats of the Lim Bay, in northern Adriatic Sea. Although the species was recorded there, there is a lack of knowledge about its biology and ecology in this region, including a reproductive cycle. Information on the reproductive biology of non-indigenous species in new areas is crucial for prediction of their future survival and possible spread in invaded habitats. In this study, we provide the first data on the reproductive biology of the Pacific oyster in the Adriatic Sea, the northernmost part of the Mediterranean Sea. Quantitative and qualitative methods of gonad tissue analysis were conducted, and effects of environmental conditions on the gametogenesis were evaluated during two reproductive cycles. Our study confirmed that environmental conditions in the Lim Bay were favourable for the reproduction of the species. The Pacific oyster reproduced once per year and had a prolonged spawning period. Water temperature was the main factor affecting gonad development and oocyte size, while chlorophyll a concentration had an impact on the oocyte development in terms of their size.
Using 14 years of environmental data, we investigated distribution of thermohaline properties and phytoplankton biomass in Mali Ston Bay, which is the major shellfish farming area on the eastern ...Adriatic coast. Sampling was conducted biweekly during summer and monthly during the rest of the year throughout period 1999-2012. Due to strong river inflow and many submarine springs, continuous thermohaline stratification was recorded throughout the entire investigated period. The salinity effect on stratification was more pronounced compared to temperature effect which was mostly expressed in summer. Phytoplankton biomass increased throughout the period 1999-2012, while a negative trend in salinity was observed for the surface layer. Seasonal biomass pattern showed two biomass peaks: the first in late winter/early spring and the second (less pronounced) in the autumn. Regarding phytoplankton size fraction; such as microplankton and nanoplankton, each component was equally represented in all seasons. Despite continuous enrichment from the Neretva River and underwater springs, lack of significant correlation between phytoplankton biomass and nutrients indicate that nutrients are quickly utilized by phytoplankton and transferred further into food web. Water column was well oxygenized throughout investigated period having high transparency and high diversity of phytoplankton taxa. According to all investigated parameters, and the fact that Mali Ston Bay is naturally productive area, and also aquaculture area, it is hypothesized whether this area could be considered as oligotrophic environment or not.
Introduction: The Republic of Croatia (HR) has significantly invested in monitoring the quality of inland bathing areas during the past 10 years. The aim of this paper was to analyze the results ...obtained during the 2014-2019 period and to compare them with the Region (non-European Union EU countries neighboring Croatia) and EU. Moreover, bathing water quality data at two bathing areas of Zagreb (lakes Jarun and Bundek) were processed in more detail. Methods: The quality of inland bathing areas in the HR is monitored in five rivers and five lakes in nine Croatian counties; 19 of the 35 monitored sites are located in Zagreb County. Escherichia coli (EC) was determined by EN ISO 9308-3: 1998, while intestinal enterococci (ENT) were defined by EN ISO 7899-2: 2000. Statistical processing of the results was performed using the Microsoft Excel Statistical Package (Redmond, USA) and Statistica 13.5. (Stat.Sof.Inc., Tulsa, USA); the significance level was set to p < 0.05. Results: During the study period, the worst Croatian inland water quality was recorded in 2019 (excellent quality for only 25.9% of the bathing areas), while the best quality was recorded in 2015 (excellent quality in 57.1%). On average (2014-2019), the share of bathing areas with excellent quality in Croatia was 46.3% (i.e., under the EU average of 85.3%); with no poor locations (EU average was nearly 2%). A significant positive correlation was found between fecal indicators (EC&ENT) and the amount of precipitation, while a negative correlation with water and air temperature in lakes. Conclusions: The quality of Croatian inland bathing areas is significantly lower than the European average, while EU water quality is improving. Regarding the countries bordering Croatia, Italy, Slovenia, and Hungary have achieved better results, while Montenegro, Serbia, and Bosnia and Herzegovina are still in the process of developing the monitoring of the bathing water quality.
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The unusual and prolonged occurrence of rare and poorly known dinoflagellate Prorocentrum arcuatum in the phytoplankton of the shallow aquaculture site in Medulin Bay was recorded from July 2013 to ...October 2014. This enabled us to investigate changes in abundance and environmental drivers of P. arcuatum population dynamics in natural conditions, and to provide first detailed description of P. arcuatum from field samples based on SEM images. During 15 months of observations we also recorded seasonal variability in P. arcuatum cell size. The optimum physical conditions for P. arcuatum proliferation were reached in autumn 2013, during the narrow temperature range between 19.6 oC – 20.4 oC, and salinity between 36.7 - 37.7. Despite the general similarity in physical conditions in autumn 2014, this increase in the abundance of P. arcuatum was not repeated, which might be connected to higher competition due to observed interannual changes in phytoplankton population structure.
Na području Medulinskog zaljeva, u razdoblju od srpnja 2013. do listopada 2014. godine, zabilježena je pojava rijetke i slabo poznate vrste dinoflagalata Prorocentrum arcuatum. Prisutnost vrste P. arcutum u fitoplanktonskoj zajednici Medulinskog zaljeva tijekom 15- mjesečnog razdoblja omogućila je istraživanje promjene u brojnosti vrste i okolišnih parametara koji uvjetuju dinamiku populacije vrste P. arcuatum u prirodnim uvjetima, a ujedno nam je omogućilo i prvi detaljni opis P. arcuatum temeljen na SEM metodologiji. Tijekom istraživanja zabilježili smo sezonsku varijabilnost u veličini stanica P. arcuatum. Optimalni fizikalni uvjeti za povećanu brojnost P. arcuatum zabilježeni su u jesen 2013. pri rasponu temperature od 19.6 oC do 20.4 oC i salinitetu 36.7 - 37.7.
Unatoč činjenici da su slični okolišni uvjeti zabilježeni i naredne godine, u jesen 2014, povećanje brojnosti P. arcuatum se nije ponovilo, što može biti povezano s većom kompetitivnošću drugih vrsta uslijed godišnjih promjena fitoplanktonske zajednice.
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An assessment of the temperature increase effect on processes within the microbial food web provides a better insight into the carbon transfer and energy flow processes in marine environments in the ...global warming perspective. Modified laboratory dilution experiments that allow simultaneous estimates of protozoan grazing and viral lysis on picoplankton groups (bacteria, Prochlorococcus, Synechococcus and pico-eukaryotic algae) under in situ and 3degreesC above in situ temperatures were performed at seasonal scale. Picoplankton mortality due to grazing was generally higher than that caused by viral lysis, especially in the cold months. The largest part of HNF carbon demand was satisfied by grazing on bacteria throughout the year. Although ciliates satisfied their carbon demand predominantly through grazing on HNF and bacteria, the role of autotrophic picoplankton (APP) as their prey increased significantly in the cold months. Bacteria constituted the most important host for viruses throughout the year. However, during the warm months, APP groups were also significant hosts for viral infection. Under the warming condition the amount of picoplankton biomass transferred to protozoan grazers exceeded the lysed biomass, suggesting that global warming could further increase picoplankton carbon flow toward higher trophic levels in the Adriatic Sea. Keywords: heterotrophic bacteria; autotrophic picoplankton; growth rate; production; protozoan grazing; viral lysis; carbon flux; global warming; Adriatic Sea
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