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Povzetek: This study provides baseline information on the feeding habits of the bull ray, Aetomylaeus bovinus (Geoffroy Saint-Hilaire, 1817), in the Gulf of Venezia. Among 1557 prey items isolated from the stomachs of bull ray specimens, gastropods represented the overwhelming majority (93.8%). Within gastropods, Aporrhais pespelecani was the dominant species, followed by Gibbula magus and Bolinus brandaris – all characteristic elements of the biocoenosis of the muddy detritic bottom. We observed differences in prey structure between juveniles and adults, as well as sexes. Among fishes that proved to be particularly important in terms of biomass, the majority of prey items consisted of small pelagic fish, including pilchard (Sardina pilchardus) and horse mackerel (Trachurus sp.). This paper contributes new data on the feeding ecology of a lesser known and critically endangered batoid species.
Ključne besede: myliobatids, feeding ecology, nursery, Gulf of Venice, batoids, endangered species, marine biology
Objavljeno v DiRROS: 03.07.2025; Ogledov: 97; Prenosov: 35
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Povzetek: In September 2024, a specimen of Maxmuelleria gigas (M. Müller, 1852) was found during a monitoring campaign in the Bay of Koper. This record is the second one of this less known macrobenthic species in the Slovenian Sea and one among few up to date reported in the Adriatic Sea, as well. Sediment mounds observed with an underwater video sledge on muddy bottom in the southern part of the Gulf of Trieste have been related to this species. The species distribution and density (47 per 100 m2) were estimated based on the quantification of the observed sediment mounds. The potential underestimation of the density and distribution of this species in the Gulf of Trieste in the past studies is discussed in relation to sampling method.
Ključne besede: Echiura, sediment mounds, videotransects, Northern Adriatic, marine biology
Objavljeno v DiRROS: 02.07.2025; Ogledov: 101; Prenosov: 41
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Povzetek: The Malaspina-2010 circumnavigation expedition on board R/V Hesperides surveyed tropical and subtropical regions of the Atlantic, Indian and Pacific oceans between December 2010 and July 2011. This article examines the relationships between the distribution of chlorophyll a (Chl a), major inorganic nutrients and other hydrographic variables. A deep chlorophyll maximum (DCM) was found at most stations between 60 and 150 m depth; it occurred close to the level of 1% surface photosynthetically active radiation and was associated with the nitracline. There was a negative relationship between total Chl a at surface and the DCM depth, and between Chl a concentration at the DCM and DCM depth. In terms of Chl a concentration, picophytoplankton was the dominant size class at all sampled light intensities (surface, 20% of surface PAR and PAR at DCM), oceans and geoclimatic zones, except at some stations influenced by upwellings or divergences. Within the Chl a concentration ranges found in this study, the proportion of picophytoplankton increased with total Chl a, in contrast with some previous findings. Vertically integrated Chl a was positively correlated with surface Chl a, with similar slopes for the whole data set and for the different oceans and zones. In turn, surface Chl a and sea surface temperature showed a negative correlation for the Indian Ocean and the subtropical zone, a positive correlation for the Atlantic, and non-significant relationships for the remaining oceans and zones.
Ključne besede: Malaspina 2010, chlorophyll a, nitracline, deep chlorophyll maximum, phytoplankton size fractionation, Atlantic Ocean, Pacific Ocean, Indian Ocean, hydrobiology, marine biology
Objavljeno v DiRROS: 04.04.2025; Ogledov: 334; Prenosov: 208
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Povzetek: Introduction: The Gulf of Trieste is prone to the accumulation of various pollutants and microplastics due to its geomorphological and hydrological characteristics. However, the distribution and sources of microplastics in this semi-enclosed area are poorly studied. The aim of our study was to determine the distribution and chemical composition of MP particles in the sediments of the Gulf of Trieste. Methods: In this study, we collected 24 surface sediment samples using a Van Veen grab. Microplastics were extracted by density separation using NaCl. The size, shape, and color of the extracted microplastics were determined using an optical microscope, and the composition of the polymers was determined by Fourier transform infrared spectroscopy. Results and discussion: The highest concentrations of up to 125 microplastic particles per 100 g dry sediment were found in coastal areas. Concentrations in the open sea were much lower, with an average of 3 particles per 100 g of sediment. Most of the microplastic was fibrous, made of polypropylene, 100–300 µm in size, and blue. This is the first study showing that microplastics are present in the sediments of the south-eastern part of the Gulf of Trieste. The findings suggest that microplastics exhibit a tendency to be retained within the sediment, leading to their accumulation primarily in a narrow coastal area rather than dispersing offshore. Our results will contribute to a better knowledge of the distribution and possible sources of plastics and microplastics in the Gulf of Trieste and even beyond in similar semi-enclosed marine areas.
Ključne besede: microplastics, sediments, Gulf of Trieste, density separation, polypropylene, accumulation of pollutants, marine biology
Objavljeno v DiRROS: 23.10.2024; Ogledov: 410; Prenosov: 1137
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Povzetek: The Workshop on ‘Establishing thresholds: workshop on the Marine Strategy Framework Directive (MSFD) Newly Introduced Non-Indigenous Species (NIS) (D2C1)’ took place online on the 24th November 2022, aiming at discussing and making progress towards establishing threshold values for the criterion D2C1. The workshop was organised by the Joint Research Centre (JRC), in collaboration with representatives of the Regional Sea Conventions (RSCs), under the MSFD Descriptor 2 Core Group, in the context of the MSFD Common Implementation Strategy Good Environmental Status Working Group. The participants to the workshop included academic and public authorities’ experts on MSFD NIS, RSCs representatives, the European Environment Agency (EEA), and Commission services. The workshop enabled sharing information on the state-of-the-art approaches on monitoring and assessment of D2C1 within Regional Seas and on the application of the time series analysis as a follow-up to Tsiamis et al. (2021) recommendations for setting threshold values. The discussion focused on ensuring comparability of approaches, how to account for uncertainties, and on areas for improvement. It was acknowledged that activities of RSCs are instrumental in coordinating the science and management of marine NIS. The various levels of monitoring across the North-East Atlantic Ocean, the Mediterranean Sea, the Baltic Sea and the EU Countries explain different methodological approaches for setting thresholds, while the limited monitoring restrict the application of these methodologies in the Black Sea. The workshop identified four main areas for improvements: i) establishment of acknowledged baselines for NIS introductions, ii) make further progress in monitoring and analysis methods, iii) agree on thresholds for new NIS introductions and, iv) ensure coherence and consistency between national and regional reports. The JRC will seek for opportunities to discuss and advance on identified areas for improvement with the MSFD national appointed NIS experts The MSFD Descriptor 2 (D2) Core Group will contribute to the discussions.
Ključne besede: Marine Strategy Framework Directive, MSFD, non-indigenous species, NIS, descriptor 2, marine biology, European Commission
Objavljeno v DiRROS: 02.09.2024; Ogledov: 636; Prenosov: 495
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