Ivan Župan

Anatomically and morphologically unique dark septate endophytic association in the roots of the Mediterranean endemic seagrass Posidonia oceanica.

Roots of terrestrial plants host a wide spectrum of soil fungi that form various parasitic, neutral and mutualistic associations. A similar trend is evident in freshwater aquatic plants and plants inhabiting salt marshes or mangroves. Marine vascular plants (seagrasses), by contrast, seem to lack specific root–fungus symbioses. We examined roots of two Mediterranean seagrasses, Posidonia oceanica and Cymodocea nodosa, in the northwestern Mediterranean Sea for fungal colonization using light and scanning and transmission electron microscopy. We found that P. oceanica, but not C. nodosa, is regularly associated with melanized septate hyphae in a manner resembling colonization by the ubiquitous dark septate endophytes (DSE) in roots of most terrestrial plants. P. oceanica roots were found to be colonized by sparse dematiaceous running hyphae as well as dense parenchymatous nets/hyphal sheaths on the root surface, intracellular melanized microsclerotia and occasionally also intra- and intercellular hyphae. The colonization was most prominent in the thick-walled hypodermis of the thinnest healthy looking roots, and the mycobiont seemed to colonize both living and dead host cells. Dark septate hyphae infrequently occurred also inside rhizodermal cells, but never colonized vascular tissues. The biological significance of this overlooked marine symbiosis remains unknown, but its morphology, extent, distribution across the NW Mediterranean Sea and absence in C. nodosa indicate an intriguing relationship between the dominant Mediterranean seagrass and its dark septate root mycobionts.

Aquaculture assessment of Noah's ark (Arca noae LINNAEUS, 1758) in the Central Adriatic Sea (Croatia)

ABSTRACT In support of aquaculture development and sustainable fisheries, survival, condition index, and stable isotope composition of the commercially important bivalve species Arca noae were investigated on individuals suspended in the water column at 2 distances from fish cages and those collected from natural populations. Significant differences were recorded in temperature and chlorophyll a with respect to season, and temperature and salinity values differed significantly with respect to sampling site. Mortality was greatest at the beginning of the experiment, probably as a result of the stress associated with collection of A. noae and the shell-marking process. The relatively small numbers of individuals that survived the experiment did not allow for a detailed statistical analysis of growth rates at the 3 study sites. Condition index showed a pronounced seasonal variation, with greater values recorded between April to July (CI, ∼24) and lesser values noted during November and December (CI, ∼20). Statistically significant intersite differences were detected. Samples collected from the control site in the Pašman Channel had lower condition index values than samples at other sites in 4 of 6 sampling months for which differences between sites were detected. Differences in stable carbon (&dgr;13CVPDB) and nitrogen (&dgr;15Nair) isotope compositions were recorded with respect to tissue type and season, but no differences with respect to sampling site were noted. Results indicate that A. noae is highly sensitive to manipulation.

Ecological quality status of the Adriatic coastal waters evaluated by the organotin pollution biomonitoring

The aim of this study was to evaluate the post-legislation change in tributyltin (TBT) pollution at Croatian Adriatic coast. Gastropod Hexaplex trunculus and sediments were collected, nearly 10years after TBT based antifouling paints were banned, at 12 locations along the coast where a previous study was conducted in 2005. The study showed a decline of TBT levels over the investigated period, although all gastropods populations were highly affected by imposex meaning that prohibition did not result in the recovery of populations. The further aim was to propose the Ecological Quality Ratio (EQR) boundaries for potential use of H. trunculus as a principal bioindicator in the assessment of the ecological status of the Mediterranean regarding TBT pollution, under the Water Framework Directive (WFD). According to the proposed EQR classes, the WFD target for achieving the Good ecological status of the marine environment by 2015 was not reached.

Increased intake of Juniperus phoenicea L. by supplementation with barley and Optigen® in sheep

Dry littoral grasslands and rocky ground pastures throughout the Mediterranean basin are a significant source of forage for small ruminants and as such associated with traditional grazing practices. During the last decade, dissemination of terpene-rich Mediterranean shrubs, Juniperus phoenicea L., onto pastures in Adriatic region of Croatia have caused reduction in forage production and plant diversity. In order to facilitate the intake of this new plant by small ruminants, we investigated the effects of barley and Optigen® (a source of controlled-release non-protein nitrogen) mixture to increase consumption of J. phoenicea by sheep. The preliminary results suggest that barley alone, or in combination with Optigen® enhance the intake of J. phoenicea by sheep. Furthermore, this model can be used as an environmentally safe and economically affordable approach to reduce the abundance of less palatable J. phoenicea in the environment and to increase growth of alternate, better quality forage (grasses and forbs) on Mediterranean pastures.

Mediterranean shrub diversity and its effect on food intake in goats

Mediterranean ecosystem offers a variety of shrubs that were over long periods of time involved in the evolution of complex plant-animal interactions. Biochemical components of these plants enter different metabolic pathways after digestion and absorption, resulting in development of dietary preferences in browsing animals. Herbivores in general were found to perform better when grazing in a mixed plant community composed of diverse species, and show preferential feeding behavioure for mixed vs single species diet. Our findings demonstrate an asymptotic relationship among Mediterranean shrubs species diversity and their voluntary intake by goats. Shrub biomass intake showed linear increase when number of different shrubs in diet increased from one to three. However, goats did not further increase intake when the number of shrub species increased from four to eight. As the number of shrub species offered increased, goats exhibited more preferential feeding behaviour for Quercus pubescens, Fraxinus ornus, Rubus heteromorphus and Arbutus unedo and decreased the intake of Hedera helix, Juniperus oxycedrus and Helichrysum italicum. This asymptotic relationship indicates that the maintenance of plant species richness in Mediterranean shrublands can overall benefit domestic goat farming, goat’s productive performance, and the conservation of plant biodiversity.

Elemental profiling of Noahs Ark shell (Arca noae, Linnaeus, 1758) by plasma optical spectrometry and chemometric tools

Determination of metal content in biominerals provides essential information with respect to relations between biomineralization processes and environmental status. Mussels are species that have a great potential as bio-marker species and therefore, they are in the focus of numerous biomineralization and ecological studies. In this study, elemental profile of mussel shell of Noahs Ark (Arca noe, Linnaeus, 1758), which inhabit eastern Adriatic Sea was obtained by determination of seventeen elements content using inductively coupled plasma optical emission spectrometry (ICP-OES). Shell samples were collected from marine protected area and from marine shipping route in eastern Adriatic Sea. The accuracy of applied analytical procedure based on microwave decomposition of shell samples was tested by use of reference materials of limestone and by matrix-matched standards. By aid of chemometric methods, the elemental profile along with variability of elements content of shell was obtained. The impact of different environment on elements content was established by use of multivariate statistical PCA method. Discernment between two groups of samples was manifested. Among results of main, minor and trace elements content, the last one which denoted to Cd, Co, Cu, Pb, and Mn was expressed as principal distinctive feature of shell samples collected from different sampling sites. Elemental profiling of mussel shell Noahs Ark provides novel insight in species status as well as in environmental status on the observed locations.

MEAGRE (Argyrosomus regius Asso, 1801) AQUACULTURE IN CROATIA

Abstract The objective of this review is to present current status of meagre aquaculture in Croatia. Meagre Argyrosomus regius (Asso, 1801) is a fast growing migratory fish species which used to be widespread along the coast of the Adriatic Sea. Today, it is very rare in fisheries catches and is considered highly endangered. Recently, meagre has become an increasingly important species in the Mediterranean aquaculture. In Croatia, meagre is a relatively new cultured species whose farming started after the year 2000. Since the European Commission identified species diversification as a top priority in the framework of the 2020 strategies for Aquaculture, and with recent studies revealing that meagre adapt easily to captivity and maintain a rapid growth rate, this species became an interesting candidate for Croatian as well as Mediterranean aquaculture.

Supplementation with imuno-2865® in gilthead sea bream (Sparus aurata Linnaeus, 1758): Effects on hematological and antioxidant parameters

The aim of this study was to evaluate the effects of IMUNO-2865(®) on hematological and antioxidative parameters in sea bream. Total of 640 sea bream were fed with diets containing 0 (Group 1), 1 (Group 2), 10 (Group 3) and 25 (Group 4) g of IMUNO-2865(®) kg(-1) feed during 90 days. Samples were taken each month and three months after the supplementation. A significant heterophils increase was observed in group 4 compared to group 1 after two months, and an increase in monocytes number was observed in group 4 compared to the other groups after one month. Glutathione peroxidase (GSH-Px) and paraoxonase-1 (PON1) were significantly increased in groups 3 and 4 compared to the control group three months into the experiment. Superoxide dismutase (SOD) was increased in group 4 compared to the control group from day 60 until the end of the experiment, and in groups 2 and 3 compared to the control after three months. Based on the differences in the cellular immunity and oxidative stress parameters, with an overall absence of mortality, the results of this study suggest that the use of IMUNO-2865(®) in aquaculture is safe and possess a cumulative immunostimulatory effect on sea bream.

Bivalve trophic ecology in the Mediterranean: Spatio-temporal variations and feeding behavior

The trophic ecology of two bivalves, the clam Callista chione and the cockle Glycymeris bimaculata was studied using environmental and biochemical variables of the suspended particulate matter and the sediment. Samples were collected from two shallow sites, Pag and Cetina, in the coastal oligotrophic Mediterranean Sea, during a 17 month period. The temporal variation of the particulate matter reflected a mixture between marine and terrestrial sources throughout the year, with a clear marine influence during summer and fall, and predominance of terrestrial inputs during spring and winter. The digestive gland was a useful rapid turnover tissue, where the carbon isotope signal was species-specific and the nitrogen isotope one was site-specific. FA markers in the digestive gland revealed a mixed diet where Callista chione fed more upon fresh material than G. bimaculata which relied largely on bacteria-derived detritus. Overall, little feeding niche overlap was observed between the two species during the year, indicating resource partitioning, expected for a food-limited system. The present trophic ecology study in co-occurring species allowed identifying species-specific feeding adaptations to environmental variability.

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Cyprinidae fish: Towards hints of their arrangements using advanced classification methods

Abstract To tackle the ever‐present global concern regarding human exposure to persistent organic pollutants (POPs) via food products, this study strived to indicate associations between organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in lake‐fish tissue depending on the species and sampling season. Apart from the monitoring initiatives recommended in the Global Monitoring Plan for POPs, the study discussed 7 OCPs and 18 PCB congeners determined in three Cyprinidae species (rudd, carp, and Prussian carp) from Vransko Lake (Croatia), which are widely domesticated and reared as food fish across Europe and Asia. We exploit advanced classification algorithms, the Kohonen self‐organizing maps (SOM) and Decision Trees (DT), to search for POP patterns typical for the investigated species. As indicated by SOM, some of the dioxin‐like and non‐dioxin‐like PCBs (PCB‐28, PCB‐74, PCB‐52, PCB‐101, PCB‐105, PCB‐114, PCB‐118, PCB‐156 and PCB‐157), &agr;‐HCH and &bgr;‐HCH caused dissimilarities among fish species, but regardless of their weight and length. To support these suggestions, DT analysis sequenced the fish species and seasons based on the concentration of heavier congeners. The presented assumptions indicated that the supplemental application of SOM and DT offers advantageous features over the usually rough interpretation of POPs pattern and over the single use of the methods. HighlightsSOM and DT classifiers searched for relation among 25 POPs in three Cyprinidae fish.The concentrations of indicator congeners dominated over dioxin‐like PCBs.Based on SOM, both dioxin‐like and indicator PCBs differentiated the fish species.DT assorted the samples on the levels of PCB‐126, ‐156, ‐170, ‐28, ‐105, and ‐114.