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Povzetek: This paper concerns records of species that have extended their distribution in the Mediterranean Sea. The finding of the rare brackish angiosperm Althenia filiformis in the island of Cyprus is interesting since its insertion in the Red Data Book of the Flora of Cyprus is suggested. The following species enriched the flora or fauna lists of the relevant countries: the red alga Sebdenia dichotoma (Greece), the hydrachnid mite Pontarachna adriatica (Slovenia), and the thalassinid Gebiacantha talismani (Turkey). Several alien species were recorded in new Mediterranean localities. The record of the burrowing goby Trypauchen vagina in the North Levantine Sea (Turkish coast), suggests the start of spreading of this Lessepsian immigrant in the Mediterranean Sea. The findings of the following species indicate the extension of their occurrence in the Mediterranean Sea: the foraminifer Amphistegina lobifera (island of Zakynthos, Greece), the medusa Cassiopea andromeda (Syria), the copepod Centropages furcatus (Aegean Sea), the decapod shrimp Melicertus hathor (island of Kastellorizo, Greece), the crab Menoethius monoceros (Gulf of Tunis), the barnacles Balanus trigonus, Megabalanus tintinnabulum, Megabalanus coccopoma and the bivalves Chama asperella, Cucurbitula cymbium (Saronikos Gulf, Greece).
Objavljeno v DiRROS: 26.03.2025; Ogledov: 115; Prenosov: 71
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Povzetek: A perceived recent increase in global jellyfish abundance has been portrayed as a symptom of degraded oceans. This perception is based primarily on a few case studies and anecdotal evidence, but a formal analysis of global temporal trends in jellyfish populations has been missing. Here, we analyze all available long-term datasets on changes in jellyfish abundance across multiple coastal stations, using linear and logistic mixed models and effect-size analysis to show that there is no robust evidence for a global increase in jellyfish. Although there has been a small linear increase in jellyfish since the 1970s, this trend was unsubstantiated by effect-size analysis that showed no difference in the proportion of increasing vs. decreasing jellyfish populations over all time periods examined. Rather, the strongest nonrandom trend indicated jellyfish populations undergo larger, worldwide oscillations with an approximate 20-y periodicity, including a rising phase during the 1990s that contributed to the perception of a global increase in jellyfish abundance. Sustained monitoring is required over the next decade to elucidate with statistical confidence whether the weak increasing linear trend in jellyfish after 1970 is an actual shift in the baseline or part of an oscillation. Irrespective of the nature of increase, given the potential damage posed by jellyfish blooms to fisheries, tourism, and other human industries, our findings foretell recurrent phases of rise and fall in jellyfish populations that society should be prepared to face.
Objavljeno v DiRROS: 26.03.2025; Ogledov: 101; Prenosov: 112
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Povzetek: Mollusc assemblages associated with Cystoseira associations were sampled in the southern part of the Gulf of Trieste during the summers of 2008 and 2012. Samples were collected by SCUBA diving in the infralittoral belt (from 1 to 4 m depth). The surface within frames of 20 x 20 cm was scraped off with sampleswere collected by hand or with an air-lift sampler. Four erected algal species were found Cystoseira barbata, C. compressa, C. corniculata and Halopithys incurva. A total of 69 species of molluscs were identified in those associations. Gastropoda were dominant, with the highest species richnessand abundance, followed bz Bivalvia and Polyplacophora. A large numberof juveniles were found, proving the importance of Cystoseira associations for mollusc recruitment. Differences in composition, structure and abundance of mollusc assemblages were found for sites dominated by different algal species, and correspond to different morphology and degree of development of canopy-forming species. The present study confirms that the dominant algal species within Cystoseira associations strongly influence, although at different levels, abundance and distribution of mollusc assemblages in the Northern Adriatic Sea.
Objavljeno v DiRROS: 26.03.2025; Ogledov: 82; Prenosov: 71
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Povzetek: In this paper, we present a refined radial basis function-generated finite difference solution for a non-Newtonian fluid in a closed differentially heated cavity. The non-Newtonian behavior is modeled with the Ostwald–de Waele power law and the buoyancy with the Boussinesq approximation. The problem domain is discretized with scattered nodes without any requirement for a topological relation between them. This allows a trivial generalization of the solution procedure to complex irregular three dimensional (3D) domains, which is also demonstrated by solving the problem in a two dimensional (2D) and 3D geometry mimicking a porous filter. The results in 2D are compared with two reference solutions that use the finite volume method in a conjunction with two different stabilization techniques, where we achieved good agreement with the reference data. The refinement is implemented on top of a dedicated meshless node positioning algorithm using piecewise linear node density function that ensures sufficient node density in the center of the domain while maximizing the node density in a boundary layer where the most intense dynamic is expected. The results show that with a refined approach, more than five times fewer nodes are required to obtain the results with the same accuracy compared to the regular discretization. The paper also discusses the convergence with refined discretization for different scenarios for up to nodes, the impact of method parameters, the behavior of the flow in the boundary layer, the behavior of the viscosity, and the geometric flexibility of the proposed solution procedure.
Objavljeno v DiRROS: 25.03.2025; Ogledov: 166; Prenosov: 55
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Povzetek: The paper addresses the construction of $C^1$ splines on a curved domain that is parametrized by a $C^0$ piecewise geometry mapping composed of quadratic Bézier triangles. The $C^1$ splines are assembled from polynomials of a chosen total degree greater than or equal to four, and their construction is based on the Clough-Tocher splitting technique that ensures locality. In particular, the splines are locally characterized by an interpolation problem described by Hermite data, which resembles the standard macro-element concepts developed for $C^1$ splines on triangulations.
Ključne besede: quadratic triangle, quadratic triangulation, isogeometric functions, Clough-Tocher refinement, spline space, dimension, basis functions
Objavljeno v DiRROS: 24.03.2025; Ogledov: 172; Prenosov: 92
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