Search results for " stable isotopes."

Isotopic Niche and Trophic Position of the Invasive Portunid Portunus segnis Forskål, (1775) in Elounda Bay (Crete Island, Eastern Mediterranean)

2022

There is a growing recognition that an advanced understanding of the trophic characteristics of an invasive consumer can provide important information on its ecological impact. In recent years, the blue swimming crab Portunus segnis, one of the earliest Lessepsian invaders, has considerably expanded its distribution range in the Mediterranean Sea, yet, its trophic habits in invaded areas remain scarcely investigated. In this study, we used carbon and nitrogen stable isotopes analysis (SIA) to determine the trophic position and isotopic niche of the crab compared with other representatives of the flora and fauna occurring in Elounda Bay (Crete). P. segnis showed a trophic position of 3.9, hi…

Stable isotope analysis of trophic niche in two co-occurring native and invasive terrapins, Emys orbicularis and Trachemys scripta elegans

2016

A trophic niche overlap in native and alien turtle species can lead to competitive interactions whereby allochthonous turtles may outcompete autochthonous individuals and eventually affect viability of natural populations. The European pond turtle (Emys orbicularis) is an autochthonous species threatened by habitat encroachment and competition with the red-eared slider (Trachemys scripta elegans). The latter is an invasive species introduced in Europe from midwestern United States as a pet and now widespread in the natural habitats of E. orbicularis. The extent of trophic competition between E. orbicularis and T. s. elegans in northern Italy was assessed by nitrogen and carbon stable isotop…

Beyond the mean: A comparison of trace- and macroelement correlation profiles of two lacustrine populations of the crayfish Procambarus clarkii

2018

In invertebrate biomonitors of chemical pollution, emphasis has been generally given to mean accumulation patterns and how they reflect varying environmental levels of contamination. Intra-population variability, and how it relates with individual phenotypic traits, has received less attention. Here, a set of analytes including trace elements (B, Ba, Cd, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, V, and Zn), macroelements (C, Ca, K, Mg, N, Na), and carbon and nitrogen stable isotopes (δ13C and δ15N) was measured in two populations of the crayfish Procambarus clarkii from Lake Trasimeno and Lake Bolsena (Central Italy). The influence of location, sex, body size, and condition factor was assessed; in ad…

Spatial variability of macrozoobenthic community and trophic structure of a subtropical lagoon in the Southeastern Atlantic coast

2013

Individual and population-scale carbon and nitrogen isotopic values of Procambarus clarkii in invaded freshwater ecosystems

2022

Este artículo contiene 16 páginas, 1 figura, 1 tablas.

Co-existing with the alien: evidence for environmental control on trophic interactions between a native (Atherina boyeri) and a non-indigenous fish s…

2022

Biological invasions are a widespread problem worldwide, as invasive non-indigenous species (NIS) may affect native populations through direct (e. g., predation) or indirect (e.g., competition) trophic interactions, leading to changes in the food web structure. The trophic relationships of the invasive eastern mosquitofish Gambusia holbrooki and the native big-scale sand smelt Atherina boyeri coexisting in three Mediterranean coastal ponds characterized by different trophic statuses (from oligotrophic to hypereutrophic) were assessed in spring through isotopic niche analysis and Bayesian mixing models. The two fish relied on the distinctive trophic pathways in the different ponds, with the …

Comparison of stable isotope composition and inorganic and organic contaminant levels in wild and farmed bluefin tuna, Thunnus thynnus, in the Medite…

2009

Abstract Stable isotope composition (δ13C and δ15N) and persistent pollutants, including heavy metals (Hg, Cd, Pb, As, Cu, Zn) and organochlorine compounds (PCBs, HCB and p,p′-DDE), were measured in muscle and liver tissues of wild and farmed bluefin tunas to investigate the changes occurring during the farming period and to assess the quality, in terms of contaminants, of the final product. At the end of farming, the food supplied was clearly integrated into the tuna tissues as derived from stable isotope signatures, and, contrarily to the literature findings obtained for other species, farmed tunas showed slight variations in persistent elements and chemical compounds in comparison with w…

The trophic transfer of persistent pollutants (HCB, DDTs, PCBs) within polar marine food webs.

2017

Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Co…

Tracking multiple pathways of waste from a northern bluefin tuna farm in a marine-coastal area.

2011

Aquaculture of bluefin tuna in Mediterranean coastal waters has generated growing concern about the negative environmental effects. In the present isotopic study we examined the dispersal and fate of organic matter derived from a Mediterranean tuna farm in the surrounding environment. An overall enrichment in the heavy nitrogen isotope was found in the feed and in farmed tunas, indicating the input of isotopically traceable organic matter in the system. Waste was clearly traceable in the water column up to 1000 m from the cages, while only slight accumulation occurred in the sediment just below the cages. Waste was isotopically shown also to contribute to the diet of demersal and benthopela…

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…