Search results for "LEVEL"
showing 10 items of 3465 documents
Baseline assessment of heavy metals content and trophic position of the invasive blue swimming crab Portunus segnis (Forskål, 1775) in the Gulf of Ga…
2018
This study provides a baseline assessment of cadmium, copper, iron, manganese, lead, and zinc concentrations in muscles, gills, and exoskeleton of the Lessepsian blue swimming crab Portunus segnis captured in the Gulf of Gabès (Southern Mediterranean Sea, Tunisia) in November 2015. Furthermore, the species’ trophic position is estimated using CN stable isotope analysis. The exoskeleton showed the lowest metal contents; in soft tissues, the essential Cu, Fe, and Zn and the non-essential Cd, Mn, and Pb showed the highest and lowest concentrations, respectively. The crab was characterized by a trophic position of 3.32, confirming its carnivorous trophic habits. Compared with literature data on…
Trophic adaptability shapes isotopic niche of the resident fish Aphanius fasciatus across lagoon habitats
2022
Abstract Coastal lagoons are characterized by high habitat heterogeneity where natural habitats coexist with artificial ones, historically set up to support human activities. Increasing anthropogenic pressure may lead to progressive degradation of the most vulnerable lagoonal habitats and the associated biological communities. One of the strictly estuarine-dependent fish species that may be affected by the degradation of lagoon habitats is the South European toothcarp Aphanius fasciatus, archetype of Mediterranean lagoon residents. Carbon and nitrogen stable isotopes were used to disentangle the influence of habitat types (natural vs artificial) and fish community (multi-trophic context) on…
Trophic and spatial complementarity on seed dispersal services by birds, wild mammals, and cattle in a Mediterranean woodland pasture
2021
Made available in DSpace on 2022-05-01T09:47:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 Università degli Studi di Palermo CYTED Ciencia y Tecnología para el Desarrollo Federación Española de Enfermedades Raras Most earth surfaces have undergone intensive land-use changes, creating habitat mosaics. Seed dispersal by animals is a crucial process in such mosaics, but community-wide studies comparing the functional complementarity and response to man-imposed habitat heterogeneity are rare. Here, we investigate the trophic and spatial seed dispersal networks underpinning a strong, woody vegetation expansion over a pastureland inside the largest forest remnant in western Sici…
Functional traits of two co-occurring sea urchins across a barren/forest patch system
2013
Abstract Temperate rocky reefs may occur in two alternative states (coralline barrens and erect algal forests), whose formation and maintenance are often determined by sea urchin grazing. The two sea urchin species Paracentrotus lividus and Arbacia lixula are considered to play a similar ecological role despite their differing morphological traits and diets. The patchy mosaic areas of Ustica Island, Italy, offer an ideal environment in which to study differences in the performance of P. lividus and A. lixula in barren versus forest states. Results show that the two sea urchin species differ in diet, trophic position, grazing adaptation, movement ability and fitness in both barren and forest…
Ecological impacts of global warming and water abstraction on lakes and reservoirs due to changes in water level and related changes in salinity
2015
According to the Intergovernmental Panel on Climate Change report released in September 2014, unprecedented changes in temperature and precipitation patterns have been recorded globally in recent decades and further change is predicted to occur in the near future, mainly as the result of human activity. In particular, projections show that the Mediterranean climate zone will be markedly affected with significant implications for lake water levels and salinity. This may be exacerbated by increased demands for irrigation water. Based on long-term data from seven lakes and reservoirs covering a geographical gradient of 52 of latitudes and a literature review, we discuss how changes in water le…
Cross-validation of δ15N and FishBase estimates of fish trophic position in a Mediterranean lagoon: The importance of the isotopic baseline
2013
Abstract FishBase, a relational database freely available on the Internet, is to date widely used as a source of quantitative information on the trophic position of marine fish species. Here, we compared FishBase estimates for an assemblage of 30 fish species sampled in a Mediterranean lagoon (Acquatina lagoon, SE Italy) with their trophic positions calculated using nitrogen stable isotopes. To assess the influence of the trophic level used to compute the baseline indicator on the robustness of isotopic estimations, we compared the trophic position of fish calculated using the average δ 15 N signature of either basal resource or primary consumer taxa measured at three stations located in th…
Assessing vermetid reefs as indicators of past sea levels in the Mediterranean
2020
Abstract The endemic Mediterranean reef building vermetid gastropods Dendropoma petraeum complex (Dendropoma spp) and Vermetus triquetrus develop bio-constructions (rims) on rocky shorelines at about Mean Sea Level (MSL) and are therefore commonly used as relative sea-level (RSL) markers. In this study, we use elevations and age data of vermetid reefs to (1) re-assess the vertical uncertainties of these biological RSL indicators, and (2) evaluate the vertical growth rates along a Mediterranean east-west transect, in attempt to explain the differences found in both growth rates and uncertainties. In Israel, Differential Global Positioning System (DGPS) and laser measurements relative to the …
Contribution of planktonic and benthic food sources to the diet of the reef-forming vermetid gastropod Dendropoma petraeum in the western Mediterrane…
2012
Abstract In the Mediterranean Sea, the vermetid Dendropoma petraeum (Monterosato, 1884) forms highly biodiverse reefs that have received increasing attention in recent years although very little is known about the food habit of this species. The main goal of this study was to describe the trophic role of planktonic and benthic food sources for D. petraeum . Specimens from three morphological zones of the reef (inner edge, cuvette and outer edge) at two sites with different wave exposure along the north-western coast of Sicily (Italy; western Mediterranean) were compared for δ 13 C and δ 15 N. Isotopic determinations were also carried out on potential food sources identified in epilithon, re…
Polyculture as a tool to increase the economic income: a study case in the Gulf of Castellammare
2010
Polyculture is a practice involving integration between organisms of different trophic levels (i.e. fish with low-trophic-level organism like molluscs and/or algae). This paper, reporting on a field experiment carried out during 2004 in the Gulf of Castellammare (South Tyrrhenian), showed that mussels transplanted in areas under fish farm influence grew up better than mussels transplanted far from fish farm. Thus, results pointed out polyculture as a reliable tool for i) increasing local bivalve production, ii) obtaining the reduction of importation from other countries and iii) increasing the environmental sustainability of fish aquaculture.
Effects of trophic and environmental conditions on the growth of Crassostrea gigas in culture
1997
In order to study the possibility of exploiting protected marine areas, comparative data on the cultivation of the oyster Cassostrea gigas in the South Tyrrenian Sea are reported. The oysters were cultured at -7 and - 13 m on long lines linked to artificial reefs. The observations, made during a 12-month period, were of the chemical-physical and trophic properties of the water column and growth rates of the oysters. Temperature ranged between 19.81 ± 4.67°C at -7 m and 18.03 ± 3.03°C at - 13 m. Salinity showed typical Mediterranean values. The area presented oligotrophic features: the chlorophyll-a (CHLa) concentration ranged between 0.05 ± 0.01 and 0.04 ± 0.02 μg 1-1 at -7 and -13 m, respe…