32 research outputs found
Recovery of high mountain Alpine lakes after the eradication of introduced brook trout Salvelinus fontinalis using non-chemical methods
The final publication is available at Springer via http://dx.doi.org/10.1007/s10530-018-1867-0Fish stocking is a serious threat to originally fishless mountain lakes. We used non-chemical eradication methods (i.e. gillnetting and electrofishing) in four high mountain lakes in the Gran Paradiso National Park (Western Italian Alps) to eradicate alien brook trout Salvelinus fontinalis. Data of amphibians, macroinvertebrates, zooplankton, chlorophyll-a, nutrient concentrations, and water transparency were used as indicators of the recovery process. All treated lakes were returned to their original fishless condition in spite of their different sizes and habitat complexity, without permanent negative side-effects for native species. Several ecological indicators showed that many impacts of introduced fish can be reversed over a short time period following eradication. The present study adds to a still growing body of specialized literature on the recovery of habitats after the eradication of alien species and provides further evidence that physical eradication methods are effective and can be part of a more general strategy for the conservation of high mountain lake biota
Why Should We Preserve Fishless High Mountain Lakes?
High mountain lakes are originally fishless, although many have had introductions of non-native fish species, predominantly trout, and recently also minnows introduced by fishermen that use them as live bait. The extent of these introductions is general and substantial often involving many lakes over mountain ranges. Predation on native fauna by introduced fish involves profound ecological changes since fish occupy a higher trophic level that was previously inexistent. Fish predation produces a drastic reduction or elimination of autochthonous animal groups, such as amphibians and large macroinvertebrates in the littoral, and crustaceans in the plankton. These strong effects raise concerns for the conservation of high mountain lakes. In terms of individual species, those adapted to live in larger lakes have suffered a higher decrease in the size of their metapopulation. This ecological problem is discussed from a European perspective providing examples from two study areas: the Pyrenees and the Western Italian Alps. Species-specific studies are urgently needed to evaluate the conservation status of the more impacted species, together with conservation measures at continental and regional scales, through regulation, and at local scale, through restoration actions, aimed to stop further invasive species expansions and to restore the present situation. At different high mountain areas of the world, there have been restoration projects aiming to return lakes to their native fish-free status. In these areas autochthonous species that disappeared with the introduction of fish are progressively recovering their initial distribution when nearby fish-free lakes and ponds are available
Exotic fish in exotic plantations: a multi-scale approach to understand amphibian occurrence in the mediterranean region
Globally, amphibian populations are threatened by a diverse range of factors including habitat
destruction and alteration. Forestry practices have been linked with low diversity and
abundance of amphibians. The effect of exotic Eucalyptus spp. plantations on amphibian
communities has been studied in a number of biodiversity hotspots, but little is known of its
impact in the Mediterranean region. Here, we identify the environmental factors influencing
the presence of six species of amphibians (the Caudata Pleurodeles waltl, Salamandra salamandra,
Lissotriton boscai, Triturus marmoratus and the anurans Pelobates cultripes and
Hyla arborea/meridionalis) occupying 88 ponds. The study was conducted in a Mediterranean
landscape dominated by eucalypt plantations alternated with traditional use (agricultural,
montados and native forest) at three different scales: local (pond), intermediate (400
metres radius buffer) and broad (1000 metres radius buffer). Using the Akaike Information
Criterion for small samples (AICc), we selected the top-ranked models for estimating the
probability of occurrence of each species at each spatial scale separately and across all
three spatial scales, using a combination of covariates from the different magnitudes. Models
with a combination of covariates at the different spatial scales had a stronger support
than those at individual scales. The presence of predatory fish in a pond had a strong effect
on Caudata presence. Permanent ponds were selected by Hyla arborea/meridionalis over
temporary ponds. Species occurrence was not increased by a higher density of streams,
but the density of ponds impacted negatively on Lissotriton boscai. The proximity of ponds
occupied by their conspecifics had a positive effect on the occurrence of Lissotriton boscai
and Pleurodeles waltl. Eucalypt plantations had a negative effect on the occurrence of the
newt Lissotriton boscai and anurans Hyla arborea/meridionalis, but had a positive effect on
the presence of Salamandra salamandra, while no effect on any of the other species was detected.
In conclusion, eucalypts had limited effects on the amphibian community at the intermediate
and broad scales, but predatory fish had a major impact when considering all the
scales combined. The over-riding importance of introduced fish as a negative impact suggests that forest managers should prevent new fish introductions and eradicate fish
from already-occupied ponds whenever possible
Seasonal variation in environmental DNA in relation to population size and environmental factors
Analysing DNA that organisms release into the environment (environmental DNA, or eDNA) has
enormous potential for assessing rare and cryptic species. At present the method is only reliably used
to assess the presence-absence of species in natural environments, as seasonal influences on eDNA in
relation to presence, abundance, life stages and seasonal behaviours are poorly understood. A naturally
colonised, replicated pond system was used to show how seasonal changes in eDNA were influenced
by abundance of adults and larvae of great crested newts (Triturus cristatus). Peaks in eDNA were
observed in early June when adult breeding was coming to an end, and between mid-July and mid-
August corresponding to a peak in newt larval abundance. Changes in adult body condition associated
with reproduction also influenced eDNA concentrations, as did temperature (but not rainfall or UV).
eDNA concentration fell rapidly as larvae metamorphosed and left the ponds. eDNA concentration
may therefore reflect relative abundance in different ponds, although environmental factors can affect
the concentrations observed. Nevertheless, eDNA surveys may still represent an improvement over
unadjusted counts which are widely used in population assessments but have unreliable relationships
with population size
Prenatal risk stratification of severe small-for-gestational-age infants: a Japanese multicenter study
Prognostic value of diffusion‐weighted magnetic resonance imaging of brain in fetal growth restriction: results of prospective multicenter study
The Relationship between the Distribution of Common Carp and Their Environmental DNA in a Small Lake
Geburtseinleitung
Die Geburtseinleitung ist ein häufig angewendetes Vorgehen, wenn eine Entbindung vor dem Einsetzen spontaner Wehen angestrebt werden soll, sie betrifft etwa 20-25 % aller Schwangerschaften. Da die Einleitung den natürlichen Verlauf der Schwangerschaft beeinflusst, muss eine entsprechende Aufklärung über die Vor- und Nachteile und die unterschiedlichen Einleitungsmethoden erfolgen und dokumentiert werden. Neben medizinischen Indikationen kann auch eine elektive "Wunscheinleitung" gerechtfertigt sein. Die unterschiedlichen Einleitungsverfahren, wie Oxytocin, Prostaglandine und mechanische Methoden, müssen abhängig von den Vorbedingungen sorgfältig gegeneinander abgewogen werden. Vor Beginn einer Einleitung muss neben der Überprüfung des fetalen und maternalen Zustands die Einleitungsindikation, das Gestationsalter und der Cervixbefund beurteilt werden