Search results for "isotopes"
showing 10 items of 1216 documents
Trophic interactions between introduced lake trout (Salvelinus namaycush) and native Arctic charr (S. alpinus) in a large Fennoscandian subarctic lake
2014
Introduced fishes may have major impacts on community structure and ecosystem function due to competitive and predatory interactions with native species. For example, introduced lake trout (Salvelinus namaycush) has been shown to replace native salmonids and induce major trophic cascades in some North American lakes, but few studies have investigated trophic interactions between lake trout and closely related native Arctic charr (S.alpinus) outside the natural distribution of the former species. We used stomach content and stable isotope analyses to investigate trophic interactions between introduced lake trout and native Arctic charr in large subarctic Lake Inarijarvi in northern Finland. …
Diet and trophic niche of the invasive signal crayfish in the first invaded Italian stream ecosystem.
2021
The occurrence of the signal crayfsh Pacifastacus leniusculus in the Valla Stream was the frst established population of this invasive species recorded in an Italian stream ecosystem. We evaluated the seasonality of diet and trophic niche of invasive signal crayfsh in order to estimate the ecological role and efects on native communities of the stream ecosystem. We studied the diferences in food source use between sexes, life stages and seasons using carbon and nitrogen stable isotope analyses. To supplement stable isotope analyses, we evaluated food source usage using traditional stomach content analysis. We tested the hypothesis that juveniles have a diferent diet, showing diferent trophi…
A review of transgenerational effects of ocean acidification on marine bivalves and their implications for sclerochronology
2020
Abstract Ocean acidification can negatively impact marine bivalves, especially their shell mineralization processes. Consequently, whether marine bivalves can rapidly acclimate and eventually adapt in an acidifying ocean is now increasingly receiving considerable attention. Projecting the fate of this vulnerable taxonomic group is also pivotal for the science of sclerochronology – the study which seeks to deduce records of past environmental changes and organismal life-history traits from various geochemical properties of periodically layered hard tissues (bivalve shells, corals, fish otoliths, etc.). In this review, we provide a concise overview of the long-term and transgenerational respo…
Guano-Derived Nutrient Subsidies Drive Food Web Structure in Coastal Ponds.
2016
A stable isotope study was carried out seasonally in three coastal ponds (Marinello system, Italy) affected by different gull guano input to investigate the effect of nutrient subsidies on food web structure and dynamics. A marked 15N enrichment occurred in the pond receiving the highest guano input, indicating that gull-derived fertilization (guanotrophication) had a strong localised effect and flowed across trophic levels. The main food web response to guanotrophication was an overall erosion of the benthic pathway in favour of the planktonic. Subsidized primary consumers, mostly deposit feeders, switched their diet according to organic matter source availability. Secondary consumers and,…
An Empirical Evaluation of the Utility of Convex Hull and Standard Ellipse Areas for Assessing Population Niche Widths from Stable Isotope Data
2013
Stable isotope analyses are increasingly employed to characterise population niche widths. The convex hull area (TA) in a δ¹³C–δ¹⁵N biplot has been used as a measure of isotopic niche width, but concerns exist over its dependence on sample size and associated difficulties in among-population comparisons. Recently a more robust method was proposed for estimating and comparing isotopic niche widths using standard ellipse areas (SEA), but this approach has yet to be tested with empirical stable isotope data. The two methods measure different kind of isotopic niche areas, but both are now widely used to characterise isotopic niche widths of populations. We used simulated data and an extensive e…
Sclerochronology - a highly versatile tool for mariculture and reconstruction of life history traits of the queen conch, Strombus gigas (Gastropoda)
2009
International audience; The queen conch, Strombus gigas, is an important fisheries resource in the Western Tropical Atlantic. In order to maintain harvesting success, improve fisheries management and contribute to mariculture pursuits, a detailed understanding of the life history traits of this species is required. Traditionally, this has been achieved by tedious and time-consuming long-term field observations. This study presents a highly versatile and rapid technique to estimate the timing and rate of shell growth based on sclerochronology. The Belizean S. gigas specimens (N = 2) from the offshore atoll, Glovers Reef, reached their final shell size (maximum shell height: 22.7 and 23.5 cm,…
Hydrogen isotopes reveal evidence of migration of Miniopterus schreibersii in Europe
2020
Abstract Background The Schreiber’s bat, Miniopterus schreibersii, is adapted to long-distance flight, yet long distance movements have only been recorded sporadically using capture-mark-recapture. In this study, we used the hydrogen isotopic composition of 208 wing and 335 fur specimens from across the species' European range to test the hypothesis that the species migrates over long distances. Results After obtaining the hydrogen isotopic composition (δ2H) of each sample, we performed geographic assignment tests by comparing the δ2H of samples with the δ2H of sampling sites. We found that 95 bats out of 325 showed evidence of long-distance movement, based on the analysis of either fur or …
Glycymeris pilosa (Bivalvia) - A high-potential geochemical archive of the environmental variability in the Adriatic Sea.
2019
Due to its outstanding longevity (decades), the shallow-water bivalve Glycmeris pilosa represents a prime target for sclerochronological research in the Mediterranean Sea. In the present study, we analyzed the microgrowth patterns and the stable carbon (δ13Cshell) and oxygen (δ18Oshell) isotopes of the outer shell layer of live-collected G. pilosa specimens from four different sites along the Croatian coast, middle Adriatic Sea. Combined analysis of shell growth patterns and temporally aligned δ18Oshell data indicated that the main growing season lasts from April to December, with fastest growth rates occurring during July and August when seawater temperatures exceeded 22 °C. Slow growth in…
Effects of Arbuscular Mycorrhizal Fungi on the Vegetative Vigor of Ailanthus altissima (Mill.) Swingle Seedlings under Sustained Pot Limitation
2018
In order to invade new ecosystems, invasive alien plants need to cope with different microbial communities. Whilst the ability to avoid antagonists is well recognized, the opportunity to establish mutualistic associations is less known, even in widespread invasive species such as Ailanthus altissima (Mill.) Swingle. We sought to evaluate whether the beneficial effects of arbuscular mycorrhizal fungi (AMF) on Ailanthus seedlings are maintained over time, under prolonged pot limitation. We compared three-month-, three-year- and four-year-old mycorrhizal seedlings grown in natural forest soil (NT) with seedlings grown in sterilized (ST) and non-mycorrhizal (NM) soils, in pots of 3.4 L (22 &tim…
Vegetated Habitats Trophically Support Early Development Stages of a Marine Migrant Fish in a Coastal Lagoon
2020
Understanding the trophic ecology of early developmental stages of commercial fish species migrating between sea and coastal lagoons is crucial to effective management of nursery habitats and resulting resources. While most information on diet shift of the gilthead seabream Sparus aurata comes from studies in experimental conditions, here we investigated the trophic niche dynamics of post-larvae, juveniles and sub-adults in natural environment, hypothesising that habitat and resources use of marine and lagoonal sites will exhibit strong relationship with ontogeny of the species. Carbon and nitrogen stable isotopes showed evidence of a clear shift in the trophic niche features, trophic posit…