13 research outputs found
Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze: Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze
In den gemäßigten Breiten zeigte
sich die allgemeine Erwärmung
der letzten Jahrzehnte
insbesondere im Winter und im
zeitigen Frühjahr. Dementsprechend
traten Veränderungen in
der Phänologie, dem zeitlichen
Verlauf von Populations- und
Entwicklungsprozessen von Organismen
(z. B. Zeitpunkt der
Knospung bei Pflanzen oder der
Laichperiode bei Fischen), vor
allem im Frühjahr auf. Obwohl
generell eine frühere und beschleunigte
Entwicklung als
Reaktion auf die Erwärmung
beobachtet wurde, zeigten sich
doch Unterschiede in der Sensitivität
von Organismen. Dadurch
kann es in Nahrungsnetzen
zu Match- oder Mismatch-
Situationen in Räuber-Beute
Beziehungen kommen. Am
Beispiel der komplexen Interaktionen
im Nahrungsnetz der
Talsperre Saidenbach wird der
Einfluss verschiedener Erwärmungsszenarien
auf Schlüsselorganismen
und deren Interaktionen
im Nahrungsnetz und
letztlich auf die Wassergüte in
dieser Trinkwassertalsperre im
Rahmen des DFG-Schwerpunktprogramms
AQUASHIFT
analysiert.In temperate regions, the warming
trends of the last decades
have been observed primarily in
winter and early spring. Accordingly,
changes in the phenology
of individual species, e.g.
sprouting in plants or spawning
of fish, occurred mainly in
spring. Although the general
pattern is earlier and faster development
in response to
warming, differences in sensitivity
have been apparent between
species, potentially giving
rise to match or mismatch scenarios
in predator-prey relations.
The impact of warming scenarios
on key species, their interactions
and ultimately on the
water quality is studied at Saidenbach
Reservoir within the
framework of the DFG priority
program AQUASHIFT
Size-dependent Predator-prey Relationships between Pikeperch and their Prey Fish
Predator-prey interactions in aquatic food webs depend on the sizes of both predator and prey. In the present study size-dependent interactions between > 70 mm total length pikeperch Sander lucioperca (L.) and four prey fish species in the biomanipulated Bautzen Reservoir were investigated. Gape widths of 597 pikeperch were measured, and the stomach contents of 806 specimens were analysed. Additionally, total lengths (TL) and body depths of 1,448 prey fish were determined. The highest prey length to predator length ratio (PPR) was 0.63. Total lengths of piscivorous pikeperch and total lengths of prey fish (pikeperch, ruffe Gymnocephalus cernuus (L.) and roach Rutilus rutilus (L.)) were positively and linearly related. This was not the case for prey perch (Perca fluviatilis L.) as all size groups of pikeperch fed strongly on age-0 perch. This study coupled with results of previous studies suggests that predation by pikeperch can have major impact on the population dynamics of especially perch.JRC.G.3-Agricultur
Riparian detritus vs. stream detritus: food quality determines fitness of juveniles of the highly endangered freshwater pearl mussels (Margaritifera margaritifera)
Detritus is an important energy source of stream food webs. Being a mix of allochthonous and autochthonous sources, it is often unknown, which components contribute to the growth of stream organisms. This study focussed on the comparison of two different detritus types (riparian detritus and stream detritus) with respect to food quality and effects on growth as a fitness parameter of juvenile freshwater pearl mussels (FPM). We performed feeding experiments with juvenile FPM under laboratory conditions using the two detritus types from four different natural sources each. Food quality was determined by analysing the fatty acid composition. Stream detritus (conditioned to stream environment including autochthonous microbes) resulted in significantly higher growth rates of juvenile FPM than predominately terrestrial-based riparian detritus indicating higher food quality. Significantly positive correlations were found between mussel growth and different groups of polyunsaturated fatty acids (PUFA). This suggests that especially trace substances such as long-chained n-3 PUFAs and a high ratio of n-3 to n-6 PUFAs enhance the food quality of stream detritus for juvenile FPM. These results highlight the importance of instream conditioning of detritus for the food mix in headwater streams and the importance of PUFAs for the development of juvenile FPM
Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze: Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze
In den gemäßigten Breiten zeigte
sich die allgemeine Erwärmung
der letzten Jahrzehnte
insbesondere im Winter und im
zeitigen Frühjahr. Dementsprechend
traten Veränderungen in
der Phänologie, dem zeitlichen
Verlauf von Populations- und
Entwicklungsprozessen von Organismen
(z. B. Zeitpunkt der
Knospung bei Pflanzen oder der
Laichperiode bei Fischen), vor
allem im Frühjahr auf. Obwohl
generell eine frühere und beschleunigte
Entwicklung als
Reaktion auf die Erwärmung
beobachtet wurde, zeigten sich
doch Unterschiede in der Sensitivität
von Organismen. Dadurch
kann es in Nahrungsnetzen
zu Match- oder Mismatch-
Situationen in Räuber-Beute
Beziehungen kommen. Am
Beispiel der komplexen Interaktionen
im Nahrungsnetz der
Talsperre Saidenbach wird der
Einfluss verschiedener Erwärmungsszenarien
auf Schlüsselorganismen
und deren Interaktionen
im Nahrungsnetz und
letztlich auf die Wassergüte in
dieser Trinkwassertalsperre im
Rahmen des DFG-Schwerpunktprogramms
AQUASHIFT
analysiert.In temperate regions, the warming
trends of the last decades
have been observed primarily in
winter and early spring. Accordingly,
changes in the phenology
of individual species, e.g.
sprouting in plants or spawning
of fish, occurred mainly in
spring. Although the general
pattern is earlier and faster development
in response to
warming, differences in sensitivity
have been apparent between
species, potentially giving
rise to match or mismatch scenarios
in predator-prey relations.
The impact of warming scenarios
on key species, their interactions
and ultimately on the
water quality is studied at Saidenbach
Reservoir within the
framework of the DFG priority
program AQUASHIFT
Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze Der Einfluss von Klimavariabilität auf aquatische Nahrungsnetze
In den gemäßigten Breiten zeigte
sich die allgemeine Erwärmung
der letzten Jahrzehnte
insbesondere im Winter und im
zeitigen Frühjahr. Dementsprechend
traten Veränderungen in
der Phänologie, dem zeitlichen
Verlauf von Populations- und
Entwicklungsprozessen von Organismen
(z. B. Zeitpunkt der
Knospung bei Pflanzen oder der
Laichperiode bei Fischen), vor
allem im Frühjahr auf. Obwohl
generell eine frühere und beschleunigte
Entwicklung als
Reaktion auf die Erwärmung
beobachtet wurde, zeigten sich
doch Unterschiede in der Sensitivität
von Organismen. Dadurch
kann es in Nahrungsnetzen
zu Match- oder Mismatch-
Situationen in Räuber-Beute
Beziehungen kommen. Am
Beispiel der komplexen Interaktionen
im Nahrungsnetz der
Talsperre Saidenbach wird der
Einfluss verschiedener Erwärmungsszenarien
auf Schlüsselorganismen
und deren Interaktionen
im Nahrungsnetz und
letztlich auf die Wassergüte in
dieser Trinkwassertalsperre im
Rahmen des DFG-Schwerpunktprogramms
AQUASHIFT
analysiert.In temperate regions, the warming
trends of the last decades
have been observed primarily in
winter and early spring. Accordingly,
changes in the phenology
of individual species, e.g.
sprouting in plants or spawning
of fish, occurred mainly in
spring. Although the general
pattern is earlier and faster development
in response to
warming, differences in sensitivity
have been apparent between
species, potentially giving
rise to match or mismatch scenarios
in predator-prey relations.
The impact of warming scenarios
on key species, their interactions
and ultimately on the
water quality is studied at Saidenbach
Reservoir within the
framework of the DFG priority
program AQUASHIFT
Prognostic significance of ALDH1A1-positive cancer stem cells in patients with locally advanced, metastasized head and neck squamous cell carcinoma
Aldehyde dehydrogenase 1 (ALDH1A1) has now been recognized as a cancer stem(-like) cells (CSCs) marker in various tumors including head and neck squamous cell carcinoma (HNSCC). The objective of this study was to examine the expression of ALDH1A1 in patients with locally advanced, metastasized HNSCC and to determine its prognostic value. Human papillomavirus genotypes and expression of ALDH1A1, Twist1, and p16 were analyzed in specimens of 81 patients with primary HNSCC and 49 lymph node metastases. Patient clinicopathologic and follow-up data were analyzed. Expression of ALDH1A1 was observed in 38 (46.9 %) of 81 primary tumors and 26 (53 %) of 49 lymph node metastases, respectively. Notably, the expression of ALDH1A1 was correlated significantly with poor tumor differentiation grade (p = 0.011). Interestingly, ALDH1A1 was observed co-expressed with Twist1 in primary tumor and lymph node metastases. Multivariate analysis showed that ALDH1A1 expression predicted poor prognosis in patients with HNSCC (p = 0.011) and the subgroup of oropharyngeal squamous cell carcinoma (p = 0.001). In the patient cohort with advanced, metastasized tumors, ALDH1A1 was identified as independent predictor of overall survival in both groups. Our results provide evidence for the prognostic value of ALDH1A1 as a CSC marker in patients with locally advanced, metastasized HNSCC
Integrating aquatic and terrestrial perspectives to improve insights into organic matter cycling at the landscape scale
Across a landscape, aquatic-terrestrial interfaces within and between ecosystems are hotspots of organic matter (OM) mineralization. These interfaces are characterized by sharp spatio-temporal changes in environmental conditions, which affect OM properties and thus control OM mineralization and other transformation processes. Consequently, the extent of OM movement at and across aquatic-terrestrial interfaces is crucial in determining OM turnover and carbon (C) cycling at the landscape scale. Here, we propose expanding current concepts in aquatic and terrestrial ecosystem sciences to comprehensively evaluate OM turnover at the landscape scale. We focus on three main concepts toward explaining OM turnover at the landscape scale: the landscape spatio-temporal context, OM turnover described by priming and ecological stoichiometry, and anthropogenic effects as a disruptor of natural OM transfer magnitudes and pathways. A conceptual framework is introduced that allows for discussing the disparities in spatial and temporal scales of OM transfer, changes in environmental conditions, ecosystem connectivity, and microbial–substrate interactions. The potential relevance of priming effects in both terrestrial and aquatic systems is addressed. For terrestrial systems, we hypothesize that the interplay between the influx of OM and its corresponding elemental composition and the elemental demand of the microbial communities – stoichiometric question – may alleviate spatial and metabolic thresholds. In comparison, substrate level OM dynamics may be substantially different in aquatic systems due to matrix effects that accentuate the role of abiotic conditions, substrate quality, and microbial community dynamics. We highlight the disproportionate impact anthropogenic activities can have on OM cycling across the landscape including reversing natural OM flows through the landscape, disrupting ecosystem connectivity, and nutrient additions that cascade across the landscape. This knowledge is crucial for a better understanding of OM cycling in a landscape context, in particular since terrestrial and aquatic compartments may respond differently to the ongoing changes in climate, land use, and other anthropogenic interferences