Search results for "Alter"
showing 10 items of 2368 documents
Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study.
2019
Abstract The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna co…
Effects of marine noise pollution on Mediterranean fishes and invertebrates: A review.
2020
International audience; Marine noise pollution (MNP) can cause a multitude of impacts on many organisms, but information is often scattered and general outcomes difficult to assess. We have reviewed the literature on MNP impacts on Mediterranean fish and invertebrates. Both chronic and acute MNP produced by various human activities - e.g. maritime traffic, pile driving, air guns - were found to cause detectable effects on intra-specific communication, vital processes, physiology, behavioral patterns, health status and survival. These effects on individuals can extend to inducing population- and ecosystem-wide alterations, especially when MNP impacts functionally important species, such as k…
Volatile Components from Aerial Parts of Centaurea diffusa and C. micrantha ssp. melanosticta and Their Biocidal Activity on Microorganisms Affecting…
2018
The chemical composition of the essential oils from aerial parts of two taxa of Centaurea belonging to subgenus Acrolophus, Centaurea diffusa Lam. and C. micrantha Hoff. ssp. melanosticta (Lange) Dostàl, respectively collected in Croatia and Spain, were evaluated by GC and GC-MS. The main components of C. diffusa were hexadecanoic acid (31.1%), ( Z,Z)-9,12-octadecadienoic acid (10.7%) and damascenone isomers (6.4%), whereas hexahydrofarnesyl acetone (27.8%), hexadecanoic acid (8.3%) and caryophyllene oxide (6.4%) were the most abundant components of C. micrantha ssp. melanosticta. The oils showed good antibacterial and antifungal activities against some microorganisms that infest historica…
Guaianolides from the Aerial Parts of Centaurea Hololeuca
2006
Seven guaianolides were isolated from the acetone extract of the aerial parts of Centaurea hololeuca Boiss. The antifeedant activity of the natural compounds (1–7) and of four chloro derivatives (8–11), synthesized from repin (1) and janerin (3) were tested against larvae of Spodoptera littoralis. Cebellin J (6) and chlorojanerin (11) showed significant antifeedant activity at 100 ppm, whereas at this concentration cebellin G (4) and 15-deschloro-15-hydroxychlorojanerin (7) stimulated feeding. Cebellin G (4) stimulated larvae of S. littoralis to feed at low concentration, but deterred feeding at high concentrations. The addition of chlorine to repin (1) resulted in an increase in antifeeda…
Seasonal dynamics of photosynthesis and total carbon gain in bearing and nonbearing pistachio (Pistacia vera L.) shoots
2018
Seasonal changes in leaf gas exchange, assimilation response to light and leaf area were monitored in bearing and nonbearing pistachio shoots. Shoot bearing status did not directly affect leaf photosynthetic rate. However, photosynthetic light-response curves strongly varied during the season demonstrating the dominant effect of the treeâs seasonal phenology on assimilation. Early in the season low photosynthetic rates were associated with high rates of dark respiration indicating limited photosynthesis in the young leaves. As leaves matured, dark respiration decreased and assimilation reached maximum values. Photosynthetic efficiency was strongly reduced late in the season due to leaf ag…
Leading role of the sea urchin Arbacia lixula in maintaining the barren state in southwestern Mediterranean
2011
Sympatric sea urchin species are usually considered to belong to the same grazer guild. Nevertheless, their role in community dynamics may vary due to species-specific morphological traits, feeding preferences and foraging behavior. In the Mediterranean Sea, the two species Paracentrotus lividus and Arbacia lixula co-occur in barren areas. Whereas P. lividus is usually considered responsible for creating a barren ground, the roles of the two sea urchin species in its maintenance are currently unclear. The relative and combined effects of P. lividus and A. lixula on maintaining the benthic community in the barren state were tested experimentally, using orthogonal exclusion of the two species…
Micropredation on sea urchins as a potential stabilizing process for rocky reefs
2012
Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other, unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we …
No evidence for differential sociosexual behavior and space use in the color morphs of the European common wall lizard (Podarcis muralis)
2020
Abstract Explaining the evolutionary origin and maintenance of color polymorphisms is a major challenge in evolutionary biology. Such polymorphisms are commonly thought to reflect the existence of alternative behavioral or life‐history strategies under negative frequency‐dependent selection. The European common wall lizard Podarcis muralis exhibits a striking ventral color polymorphism that has been intensely studied and is often assumed to reflect alternative reproductive strategies, similar to the iconic “rock–paper–scissors” system described in the North American lizard Uta stansburiana. However, available studies so far have ignored central aspects in the behavioral ecology of this spec…
Territoriality versus flocking in the Zenaida dove (Zenaida aurita): resource polymorphism revisited using morphological and genetic analyses.
2011
11 pages; International audience; The term “resource polymorphism” refers to the existence of alternative phenotypes in relation to resource use, as a result of disruptive selection. Evidence for resource polymorphism is widespread in fish but remains scarce in birds. Although Zenaida Doves (Zenaida aurita) usually defend year-round territories, doves on Barbados can also be observed foraging at seed-storage sites in large flocks with little, if any, inter-individual aggression. On the basis of morphological variation, it has been suggested (Sol et al. 2005) that this represents a case of resource polymorphism, primarily driven by competition for territories. Using new data, we revisited th…