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Abstract: Aurelia aurita s.l. is the most widespread scyphozoan jellyfish that recurrently appear “en mass” and forms large aggregations mainly in coastal waters, embayments and estuaries. Beside anthropogenic factors controlling jellyfish populations climate change may play an important role. The aim of this study was to assess whether climate-related factors in absence of other anthropogenically induced stressor influence medusae size. We investigated seasonal and interannual changes in the size of Aurelia in a “jelly lake” in the National Park of Mljet Island (Croatia) where minimal human impact on the environment makes the Veliko Jezero a natural mesocosm for understanding the impact of climate change on the Aurelia population. The observed changes suggest Aurelia medusa population response to changing environment, in particular to enhanced temperature, by reduced body sizes. Comparison of Aurelia population dynamics from different regions in the Mediterranean Sea revealed the unique feature of the Veliko Jezero population. Despite the similarity of the environmental windows of medusae occurrences in the Veliko Jezero and regions in the Mediterranean Sea, medusae in the Veliko Jezero are present all year round. It seems that the lake bathymetry enables medusae to vertically migrate to deeper and cooler water layer, avoiding the limiting temperatures developed in the upper layer during the summer. These conditions may prolong the Aurelia medusae life span and together with continuous strobilation support the stability of the Aurelia medusae population all year round.
Keywords: Mediterraneum, moon jellyfish, Adriatic Sea, South Adriatic Sea, marine lakes, Aurelia spp, climate-related factor, Mediterranean Sea, marine research, population dynamics
Published in DiRROS: 05.08.2024; Views: 323; Downloads: 157
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Abstract: During two cruises of the MEDUZA experiment conducted in July 2003 and May 2005 various data were obtained over the deepest part of the southern Adriatic Pit. Temperature, salinity, light transmission and fluorescence were measured in July 2003. During May 2005, except CTD measure- ments the samples were taken for laboratory determination of phytoplankton pigments with HPLC technique. During both cruises irradiance and radiance were measured at 14 wavelengths in the range 340-715 nm with optical probe to about 100 m depth. Bad weather conditions during both cruises caused interruption of measurements that continued after 24 to 48 hours. Stormy conditions have resulted in a slightly different structure of the water column. In the periods of measurements recorded were diurnal rhythms in a series of parameters, caused by solar radiation cycles in the surface layers as well as fluctuations in the deeper layers under the influence of the internal tide. Meteorological conditions and changes in sea level are also described. The analysis included the principal component and correlation analysis between the measured and derived parameters in order to establish a link between the in-situ pigments and multispectral data. During both cruises diurnal vertical oscillations were observed in biotic and abiotic parameters. Chlorophyll pigments prevailed over other pigments preventing other pigments to be distinguished spectrally. Regression models for chlorophyll a were established from radiance and reflectance ratios.
Keywords: termohaline properties, vertical migrations, Adriatic, South Adriatic Sea, diurnal rhithm, open sea, internal tide, Adriatic
Published in DiRROS: 05.08.2024; Views: 494; Downloads: 272
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Abstract: In order to assess the spatial distribution and temporal trends of pollution with metals in the coastal sea of Slovenia, the level of metallothioneins (MT) was determined in blue mussels from three sampling locations, twice per year for a period of 10 years. MT concentrations ranged from 45 to 163 μg g-1 w.w. in March, and from 46 to 144 μg g-1 w.w. in the September sampling. The metals content was determined in whole mussel tissue once per year at two stations. The cadmium (Cd) concentration was in the range from 0.50 to 1.11 mg kg-1, while the concentration of mercury (Hg) was in the range from 0.70 to 0.237 mg kg-1. Results revealed no significant seasonal differences or differences between sampling sites in MT content, as well as variations in the content of Cd and Hg in mussels’ tissue during the examined period. The MT and metal content in mussels are not well correlated and other factors may have caused the fluctuations observed in MT content between years. This supports the notion that biomonitoring data have to be interpreted cautiously, taking into account various other factors that may influence MT induction.
Keywords: monitoring, coastal waters, biodiversity, bio-indicators, macrozoobenthos, metallothioneins, biocoenoses, ecological aspects, Gulf of Trieste
Published in DiRROS: 05.08.2024; Views: 878; Downloads: 164
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Abstract: We describe different aspects of the reproductive biology, mating behavior, and vibratory communication of the pentatomid Edessa meditabunda (Fabr.). This species shows lower copulation frequency and reproductive potential with longer sexual maturation period compared to other species of pentatomids. Females with multiple mating show increased fecundity when compared with single-mated females and both increased fecundity and reduced longevity when compared with virgin females. Courtship and mating behavior and vibratory signals are typical and similar to what was observed in other species of pentatomids, except that males started the courtship. These results constitute the first paper on biology, behavior, and vibratory communication among species of the subfamily Edessinae.
Keywords: animal ecology, animal communication
Published in DiRROS: 05.08.2024; Views: 483; Downloads: 322
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Abstract: Background With the increasing number of GMOs on the global market the maintenance of European GMO regulations is becoming more complex. For the analysis of a single food or feed sample it is necessary to assess the sample for the presence of many GMO-targets simultaneously at a sensitive level. Several methods have been published regarding DNA-based multidetection. Multiplex ligation detection methods have been described that use the same basic approach: i) hybridisation and ligation of specific probes, ii) amplification of the ligated probes and iii) detection and identification of the amplified products. Despite they all have this same basis, the published ligation methods differ radically. The present study investigated with real-time PCR whether these different ligation methods have any influence on the performance of the probes. Sensitivity and the specificity of the padlock probes (PLPs) with the ligation protocol with the best performance were also tested and the selected method was initially validated in a laboratory exchange study. Results Of the ligation protocols tested in this study, the best results were obtained with the PPLMD I and PPLMD II protocols and no consistent differences between these two protocols were observed. Both protocols are based on padlock probe ligation combined with microarray detection. Twenty PLPs were tested for specificity and the best probes were subjected to further evaluation. Up to 13 targets were detected specifically and simultaneously. During the interlaboratory exchange study similar results were achieved by the two participating institutes (NIB, Slovenia, and RIKILT, the Netherlands). Conclusions From the comparison of ligation protocols it can be concluded that two protocols perform equally well on the basis of the selected set of PLPs. Using the most ideal parameters the multiplicity of one of the methods was tested and 13 targets were successfully and specifically detected. In the interlaboratory exchange study it was shown that the selected method meets the 0.1% sensitivity criterion. The present study thus shows that specific and sensitive multidetection of GMO targets is now feasible.
Keywords: geneticallz modified organisms, GMO
Published in DiRROS: 05.08.2024; Views: 434; Downloads: 282
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