SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "db:Swepub ;srt2:(2010-2011);lar1:(umu);lar1:(hkr)"

Sökning: db:Swepub > (2010-2011) > Umeå universitet > Högskolan Kristianstad

  • Resultat 1-4 av 4
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Dessborn, Lisa, 1976-, et al. (författare)
  • Pike predation affects breeding success and habitat selection of ducks
  • 2011
  • Ingår i: Freshwater Biology. - : Wiley: 12 months. - 0046-5070 .- 1365-2427. ; 56:3, s. 579-589
  • Tidskriftsartikel (refereegranskat)abstract
    • 1. Fish and ducks often belong to the same local food web, and several studies indicate that there is a general negative effect of fish on breeding ducks. This pattern has so far been addressed mainly within the framework of competition for common invertebrate prey, while predation by large fish as a force behind settlement and abundance patterns in ducks remains largely unknown. This is the first study to address the effect of fish predation on breeding ducks, isolated from that of competition, and the first experiment to explore the ability of ducks to identify and avoid lakes with high risk of fish predation. 2. We used a before-after control-impact design and 11 naturally fishless lakes. Waterfowl on the lakes were surveyed during the breeding season of 2005. Large adult pike (Esox lucius) were added to two lakes in early spring 2008, and waterfowl surveys were repeated on all 11 lakes. 3. Pike introduction did not affect the number of pairs on lakes during the nesting season in any of three focal duck species (mallard Anas platyrhynchos, teal Anas crecca, and goldeneye Bucephala clangula). During the brood-rearing season, however, there was a decrease in duck days in teal and goldeneye in lakes with pike, with similar trends observed in mallard. The number of goldeneye ducklings was also significantly lower in lakes with pike. We were unable to determine whether the response was attributable to direct pike predation or to broods leaving experimental lakes, but in either case, our study demonstrates high fitness costs for ducks breeding on lakes with pike. 4. The apparent inability of nesting ducks to detect pike and the clear fitness implications may influence the annual recruitment of ducks on a larger scale as pike are both common and widespread. Vegetation complexity and food abundance are likely to be of overriding importance when breeding ducks are choosing a nesting site. As pike have a strong influence on breeding birds, relying on vegetation and cues of food abundance, while ignoring indicators of predation risk from fish, could lead to lakes with pike acting as an ecological trap.
  •  
2.
  • Elmberg, Johan, 1960-, et al. (författare)
  • Presence of fish affects lake use and breeding success in ducks
  • 2010
  • Ingår i: Hydrobiologia. - : Springer. - 0018-8158 .- 1573-5117. ; 641:1, s. 215-223
  • Tidskriftsartikel (refereegranskat)abstract
    • Several previous studies indicate that presence of fish has negative effects on waterbirds breeding on lakes, owing either to competition for common invertebrate prey or fish predation on ducklings/chicks. However, others have reported results to the contrary and it remains unresolved what factors trigger, inhibit, and modulate fish-waterbird interactions. The present study was designed to test the effect of fish presence per se, with a minimum of variation in possibly confounding environmental variables. Thus, after stratifying for area, depth, altitude, pH, and total phosphorus we compared 13 lakes with and 12 without fish (mainly pike Esox lucius and perch Perca fluviatilis) with respect to (i) general species richness of waterbirds, (ii) species-specific utilization and breeding success of two dabbling ducks (mallard Anas platyrhynchos and teal Anas crecca) and a diving duck (goldeneye Bucephala clangula). General species richness of waterbirds was higher on fishless lakes. Overall use (bird days) and brood number of teal and goldeneye were higher on fishless lakes. The latter also had more benthic and free-swimming prey invertebrates compared to lakes with fish. Mallard use, mallard brood number, and abundance of emerging insects did not differ between lake groups. Generalized linear models including fish presence as factor and considering seven environmental variables as covariates, confirmed that all waterbird variables except mallard days and broods were negatively correlated to fish presence. There was also a residual positive relationship of lake area on general species richness, teal days, and teal broods. Our data demonstrate a stronger effect of fish presence on diving ducks and small surface feeding ducks than on large surface-feeding ducks. We argue that observed patterns were caused by fish predation on ducks rather than by fish-duck competition for common prey.
  •  
3.
  • Hladyz, Sally, et al. (författare)
  • Stream ecosystem functioning in an agricultural landscape : the importance of terrestrial-aquatic linkages
  • 2011
  • Ingår i: Ecosystems in a human-modified landscape. - San Diego : Academic Press. - 9780123747945 ; 44, s. 211-276
  • Bokkapitel (refereegranskat)abstract
    • The loss of native riparian vegetation and its replacement with non-native species or grazing land for agriculture is a worldwide phenomenon, but one that is prevalent in Europe, reflecting the heavily-modified nature of the continent's landscape. The consequences of these riparian alterations for freshwater ecosystems remain largely unknown, largely because bioassessment has traditionally focused on the impacts of organic pollution on community structure. We addressed the need for a broader perspective, which encompasses changes at the catchment scale, by comparing ecosystem processes in woodland reference sites with those with altered riparian zones. We assessed a range of riparian modifications, including clearance for pasture and replacement of woodland with a range of low diversity plantations, in 100 streams to obtain a continental-scale perspective of the major types of alterations across Europe. Subsequently, we focused on pasture streams, as an especially prevalent widespread riparian alteration, by characterising their structural (e.g. invertebrate and fish communities) and functional (e.g. litter decomposition, algal production, herbivory) attributes in a country (Ireland) dominated by this type of landscape modification, via field and laboratory experiments. We found that microbes became increasingly important as agents of decomposition relative to macrofauna (invertebrates) in impacted sites in general and in pasture streams in particular. Resource quality of grass litter (e.g., carbon : nutrient ratios, lignin and cellulose content) was a key driver of decomposition rates in pasture streams. These systems also relied more heavily on autochthonous algal production than was the case in woodland streams, which were more detrital based. These findings suggest that these pasture streams might be fundamentally different from their native, ancestral woodland state, with a shift towards greater reliance on autochthonous-based processes. This could have a destabilizing effect on the dynamics of the food web relative to the slower, detrital-based pathways that dominate in woodland streams.
  •  
4.
  • Lindahl, Britt, et al. (författare)
  • Socio-scientific Issues : A Way to Improve Students’ Interest and Learning?
  • 2011
  • Ingår i: US-China Education Review B. - New York : David Publishing Company. - 2161-6248 .- 1548-6613 .- 1930-1529. ; 8:9, s. 342-347
  • Tidskriftsartikel (refereegranskat)abstract
    • According to many documents, there is a strong need to renew science education. One way could be to work with SSI (socio-scientific issues). This paper reports on both students' and teachers' experiences and learning when working with socio-scientific issues in science education in secondary school (aged from 13 to 16). The approach is multidimensional, as factors that influence cognition as well as motivation and the forming of attitudes are complex. Results suggest that SSI work forms are more important than personal factors for explaining outcomes. Relevant issues, autonomy and functioning group work seem to be important aspects of successful SSI work together with structure provided by the teacher, and information that challenges previous knowledge. In general, SSI seems to be most efficient for students, who believe that they learn from presenting and discussing their knowledge, focus on "the large picture", acknowledge own responsibility for learning, find school science personally relevant and are self-efficacious. It seems that the outcomes from SSI work are much in the hands of the teacher. This paper is a short summary of the first year and quantitative part of the project. Further results from the project will later be found in our homepage (http://www.sisc.se). 
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-4 av 4

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy