Search results for "Behaviour"

Effect of boat noise on the behaviour of bluefin tuna Thunnus thynnus in the Mediterranean Sea

2007

The effect of boat noise on the behaviour of bluefin tuna Thunnus thynnus was investi- gated in the Egadi Islands, Sicily, during spring 2005 using a fixed tuna trap set near shipping routes. Tuna behaviour was observed when exposed to both natural ambient sound and sound generated by hydrofoil passenger ferries, small boats and large car ferries. Acoustical and behavioural analyses were conducted with and without extraneous sound to define a list of behavioural categories. Each vessel produced different engine sounds with regard to their composition and bandwidth, and all were distinctly different from ambient sound levels. In the absence of boat noise, tuna assumed a con- centrated coordi…

The new Lessepsian entry Brachidontes pharaonis (Fischer P., 1870) (Bivalvia, Mytilidae) in the western Mediterranean: A physiological analysis under…

2000

The feeding behavior of Brachidontes pharaonis (Mollusca, Bivalvia), a new Lessepsian entry in the western Mediterranean, living in a cooling vat of a saltworks system in western Sicily, was assessed by estimating its physiological rates throughout a 6 month-long study (May 1998 to March 1999). Clearance, filtration, ingestion, and food absorption rates were estimated using the biodeposition method and the results correlated to variations in temperature, salinity, and quality and quantity of available food. Measured seston concentrations were on average 81.5 ± 95.5 mg L-1, its labile fraction (estimated as the sum of particulate lipids, carbohydrates and proteins) was on average 0.55 ± 0.07…

Sedimentary and particulate organic matter: mixed sources for cockleCerastoderma glaucumin a shallow pond, Western Mediterranean

2007

Seasonal changes in feeding habits and diet of the cockle Cerastoderma glaucum (Mollusca, Bivalvia) were analysed using carbon (δ 13 C) and nitrogen (δ 15 N) stable isotopes. I aimed to investigate the role of benthic and pelagic sources in the diet of this dominant infaunal bivalve on a western Mediterranean sandy bottomed pond. Adult C. glaucum and all potential organic sources (particulate and sedimentary organic matter, seagrass, macroalgae, het- erotrophic detritus) were collected and analysed for δ 13 Ca ndδ 15 N. In total 5 dominant organic sources were found, ranging between -21.0 and -8.0%� for δ 13 C and from 3.0 to about 7.0%� for δ 15 N. C. glaucum assimilated fraction ranged be…

Effects of Ocean Acidification on physiology, behaviour and ecology of fish

CO2 concentration in the atmosphere is increasing at unprecedented rate since the last 800,000 years due to rising fossil fuel combustion, industrial processes and land use by humans. By absorbing part of this gas from the atmosphere, Oceans contribute to the mitigation of climatic changes, but at the cost of greater modifications of their physical and chemical characteristics. CO2 dissolved in the seawater leads to increased bicarbonate (HCO3 -) and hydrogen ions (H+) concentrations with a consequent pH drop, a phenomenon known as Ocean Acidification (OA). If global policy will not put in force mitigation measures to reduce CO2 emissions, it is projected that partial pressure of dissolved …

AN ANALYSIS OF SURFACE ACTIVITY OF BEACH RESIDENT INVERTEBRATE COMMUNITY DURING STORM EVENTS

2022

Increasing storminess is among the expected effects of climate change; systems such as sandy beaches –and especially those on islands- are particularly exposed to these events. Data related to behavioural reactions of resident beach fauna to storms could hence provide useful insights for the study of beaches’ resilience. A study was carried out on two beach units on the NE coast of Crete island (Greece), seasonally subjected to violent storms. Daily surface activity of resident fauna was analysed through temporal replicates (four different moon phases) during the months of March and April 2016. Pitfalls were placed along transects perpendicular to the shoreline and emptied every three hours…

Impact of a single, intense prenatal stress on ethanol drinking behaviour and cognition in adult male rats

2015

Early exposure to stressful stimuli is crucial for developing varied behavioural patterns in adulthood such as anxiety, cognitive dysfunction and abuse disorders. The alteration of the hypothalamic–pituitary–adrenal (HPA) axis represents the neurobiological substrate responsible of the behavioural consequences of prenatal stress (PS). Indeed, prenatal manipulation of the HPA axis impacts on cognitive performance of the adult offspring, but also on vulnerability to alcohol consumption. Prenatal acute, moderate restraint stress has proved to facilitate HPA axis development of the offspring, since maternal corticosterone secretion leads to the reduction of anxiogenic behaviour and an improveme…

The Effects of Structure on the One Dimensional Compression Behaviour of a Porous Calcarenite

2019

Human settlements built on weak rock deposits are often characterized by instabilities or collapse that may involve the underground cavities and consequently the above buildings. Underground calcarenite quarries in Marsala have been involved in a number of collapses that have seriously damaged numerous buildings. Unfortunately proper engineering solutions have not yet been identified according to the different and special cases and to the properties of this structured material. In order to investigate structure effects on the behaviour of the porous calcarenite of Marsala, this paper presents a comparison between the one dimensional compression behaviour of the intact rock and of the same w…

An experimental and constitutive investigation on the chemo-mechanical behaviour of a clay. In Bio- and Chemo- Mechanical Processes in Geotechnical E…

2014

Engineering issues for which the understanding of the chemo-mechanical behaviour of soils is relevant include wellbore stability problems, the salinification of groundwater, and nuclear waste storage. However, despite the vast number of situations in which couplings between chemistry and mechanics occur, the available constitutive models rely on limited experimental evidence. This paper presents the results of an experimental programme on the chemo-mechanical behaviour of a non-swelling illite. The osmotic suction is controlled through the ion concentration of sodium chloride in the pore water. Stress paths include mechanical loading at a constant osmotic suction, and an increasing osmotic …

Microstructure and mechanical behaviour of a saturated compacted scaly clay

2011

The paper presents the results of a research on the influence of structure characteristics on the mechanical behaviour of a saturated compacted scaly clay. To this aim, mechanical properties of compacted scaly clay samples after saturation are compared with the corresponding properties measured on the clay reconstituted in the laboratory. For the stress range explored in the experimental programme, compacted scaly clay samples are stiffer and stronger than reconstituted clay samples owing to their greater density. Collected results are discussed taking in consideration microstructure characteristics of the compacted and reconstituted clay samples

Case Study of the Structural Behavior of a Catalan Bricks Masonry Vault

2015

Catalan vaults are a peculiar type of low thickness vaulted brick masonry structure. Knowledge of load-deflection response and load bearing capacity are important aspects to consider with the aim of preserving these structural members as part of the cultural heritage. In order to investigate these aspects, complete knowledge of the constituent materials and geometry (dimension, thickness, constructive section) is necessary in such a way as to predict the load-deflection response and the effective load-carrying capacity; the latter can be determined utilizing simplified models (limit analysis) or by means of a numerical analysis (finite element method). With this aim, the structural behaviou…