För ungefär en månad sedan uppmärksammade vi en forskningsartikel som handlade om hur grågåsen genom sin spillning är viktig för växters spridning på skärgårdsöar i Östersjön (läs inlägget här). Lutz Eckstein, Professor i NRRV, är medförfattare på artikeln.

Nu har forskningen fått stort mediegenomslag, och uppmärksammats av bland annat Sveriges Radio (lyssna på ett inslag där Lutz berättar om studien), Aftonbladet, Svenska Dagbladet, Ny Teknik samt en mängd lokaltidningar (Smålandsposten, Kristianstadsbladet, Bohuslänningen, Enköpingsposten, Borås tidning, Uppsala nya tidning, Katrineholms-Kuriren m.fl.).

Anna Hagelin’s PhD thesis nailed at the main entrance at Karlstad University.

PhD-defense: Conservation of landlocked Atlantic salmon in a regulated river

On Friday 12 April, Anna Hagelin will defend her PhD-thesis “Conservation of landlocked Atlantic salmon in a regulated river – Behaviour of migratory spawners and juveniles”. The defense will take place at 10:00 in room 1B309 (Sjöströmssalen) at Karlstad University. Everyone is welcome to attend the defense.

Ian Fleming (Memorial University of Newfoundland (Canada) will be the opponent and Jaakko Erkinaro (Natural Resources Institute, Finland), Eva Thorstad (Norwegian institute for Nature Research, Norway) and John Armstrong (Marine Scotland Science Freshwater Fisheries Laboratory, Scotland) constitute the grading committee.

 

Mini-symposium on Atlantic salmon

On Thursday 11 April, a mini-symposium on Atlantic salmon will be held in room 5F322 at Karlstad University, where the visiting researchers will give presentations:

 

Anna Hagelin nailed her thesis at the biology department at Karlstad University on Friday 22 March.

14:00-14:30: Ian Fleming, Memorial University of Newfoundland. Life-history dependent migration strategies in Atlantic salmon 

14:30-15:00: Jaakko Erkinaro, Natural Resources Institute Finland. Diversity in Atlantic salmon – evolutionary ecology and management implications 

15:00-15:30: Coffee break

15:30-16:00: Eva Thorstad, Norwegian Institute for Nature Research. Status of salmon in Norway and importance of the ocean phase 

16:00-16:30: John Armstrong, Marine Scotland Science Freshwater Fisheries Laboratory. Current and future applications of science for management of salmon in Scotland

Åsa Enefalk, Ari Huusko, Pauliina Louhi and Eva Bergman recently published the paper “Fine stream wood decreases growth of juvenile brown trout (Salmo trutta L.)” in the journal Environmental Biology of Fishes. In the abstract, the authors write:

A juvenile brown trout (Salmo trutta) hiding in fine stream wood.

“In this study, the growth rate, gut fullness, diet composition and spatial distribution of brown trout was compared between artificial channels with and without fine wood (FW). Access to FW resulted in significantly lower brown trout growth rates over the study period from late summer to early winter as water temperatures declined from 17 °C to 1 °C. Access to FW resulted in minor differences in occurrence of the most common taxa found in brown trout diets, except for chironomid larvae which were found in c. 60% of the brown trout guts from control treatments but in only 30% of the guts from FW treatments in early winter. Diet consisted primarily of case-bearing and free-living Trichoptera larvae, Asellus, chironomid and Ephemeroptera larvae. Brown trout gut fullness was not significantly affected by access to FW bundles. Brown trout aggregated among FW but were more evenly distributed in channels lacking it. Our results suggest that juvenile brown trout use FW as a shelter at a wide range of water temperatures, and that this behaviour may result in reduced growth rates during their first fall and the onset of their first winter. We also show that prey availability and the composition of brown trout diet changes from late summer to early winter and that FW has a small but significant effect on brown trout diet composition.”

Read the paper here, or contact any of the authors.

Dirk Hattermann, Markus Bernhardt-Römermann, Annette Otte  and Lutz Eckstein recently published the paper “Geese are overlooked dispersal vectors for vascular plants in archipelago environments” in Journal of Vegetation Science.

 

In the abstract, the authors write:

 

“Question

We addressed the importance of gut‐mediated dispersal by Greylag Goose for vascular plants in archipelago environments and asked:

(i) What proportion of the local species pool is dispersed by geese?.

(ii) Which plant traits characterize species dispersed by geese?.

(iii) Which plant communities are likely to benefit from endozoochory by geese?.

 

Location

Three Swedish Baltic archipelagos.

 

Methods

Goose droppings were collected on 45 islands. Plants germinating from the droppings represent the endozoochorous species pool (ESP). On 108 islands, the presence of vascular plants was recorded in each habitat. These species represent the island species pool (ISP). Differences in functional traits between ESP and ISP were expressed as effect sizes and tested using meta‐regressions. Using indicator species analyses and indicator species for managed semi‐natural grasslands, we identified the primary habitats of the ESP.

 

Results

Geese dispersed viable diaspores of 97 plant species, which represents 22% of the ISP. Most ESP species were typical for small islands. Geese dispersed a higher proportion of graminoids and less woody plants, higher proportions of chamaephytes and therophytes and less phanerophytes; annuals and bi‐annuals were significantly overrepresented. One average, seed volume of the ESP was 95 % smaller than that of the ISP. About 51% of all ESP species were dispersed in at least two archipelagos. Geese showed a bias towards species of rocky shore habitats.

 

Conclusion

Geese potentially disperse large amounts of diaspores of many terrestrial island plant species. Through their feeding behaviour, geese select species with certain suites of traits from the regional species pool. Plant dispersal by geese may benefit plants species of rocky shores, but species of formerly managed semi‐natural grasslands may also find refuge sites on epilittoral shores after goose‐mediated dispersal. The relative importance of geese as dispersal vectors may increase under ongoing land‐use changes and cessation of grazing networks.”

 

Access the paper here, or contact any of the authors.

Seminarium om modellering

Posted by Karl Filipsson | Seminar

På fredag 15 mars kommer Ola Nordblom från DHI (som arbetar med vattenmiljöer, med tonvikt på avancerad tillämpning av beräkningsmodeller) till Karlstads universitet. Klockan 11:00 kommer det att vara ett öppet diskussionsseminarium, där (1) Ola presenterar DHIs verksamhet och hur ekologisk forskning kan vara av intresse för deras framtida projekt, och (2) forskargruppen NRRV presenterar sina forskningsområden och framtida behov av samarbeten kring modellering.

Seminariet kommer hållas i rum 5F416.

Forskare, doktorander och studenter är välkomna!

On Tuesday 5 March (tomorrow) Anna Hagelin, PhD student at Karlstad University, will give a pre-dissertation talk titled “Conservation of landlocked Atlantic salmon in a regulated river: behaviour of migratory spawners and juveniles”. The seminar starts at 13:15 in room 5F416. Everyone is welcome to attend the seminar.

Anna will defend her doctoral thesis on 12 April at 10:00 in room 1B309 at Karlstad University. More information will come closer to the dissertation.

Two papers in Animal Conservation

Posted by Karl Filipsson | Papers

Two papers from NRRV were recently published in the journal Animal Conservation. The first paper presents a field study on how sedimentation affects brown trout (Salmo trutta) fry emergence in relation to freshwater pearl mussel (Margaritifera margaritifera) recruitment. The second paper presents a combined field and laboratory study on passage solutions for upstream-migrating eels (Anguilla anguilla).

 

Sedimentation affects emergence rate of host fish fry in unionoid mussel streams

Martin Österling

 

In the abstract, the author writes:

Freshwater pearl mussel, Margaritifera margaritifera

“Free-living, sympatric sedentary life stages of hosts and parasites are often adapted to similar environmental conditions. When the environment where these life stages occur is disturbed, both species can decline, causing strong negative effects on the parasitic species. For the highly threatened unionoid mussels with their larval parasitic life stage on fish, habitat degradation may simultaneously affect the conditions for the sedentary host fish eggs and the juvenile mussels in the sediment. This study provides novel information on the effect of sedimentation on the emergence rate of yolk sac fry, and its relation to mussel recruitment in two drainage basins, and is exemplified by the brown trout Salmo trutta, host fish for the threatened freshwater pearl mussel Margaritifera margaritifera. The results imply that turbidity and sedimentation can reduce the survival of trout eggs and yolk sac fry emergence rate regardless of trout strain and drainage basin. The results further suggest that low yolk sac fry emergence rates reduce the potential for mussel infestation and recruitment. The results indicate a year round negative effect of sedimentation, having strong and combined direct and indirect effects on juvenile mussel recruitment. Conservation measures that reduce anthropogenic sediment transportation into streams are a key factor for the conservation of mussels and their host fish.”

Access the paper here, or contact the author.

 

Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers

Johan Watz, Anders Nilsson, Erik Degerman, Carl Tamario and Olle Calles

 

European eel, Anguilla anguilla. Photo: Jörgen Wiklund

In the abstract, the authors write:

“Conservation programmes for endangered, long-lived and migratory species often have to target multiple life stages. The bottlenecks associated with the survival of juvenile anguillid eels migrating into inland waters, the survival and growth of the freshwater life stage, as well as the recruitment and survival of silver eels, migrating back to the ocean to spawn, must be resolved. In this study, we focus on the efficiency of passage solutions for upstream-migrating juveniles. Such solutions can consist of inclined ramps lined with wetted climbing substrata. We evaluated different commonly used substrata in a controlled experiment, recorded eel behaviour at the entrance of the ramp with infrared videography and validated the experimental results at a hydropower dam, where we also investigated the effects of ramp placement on performance. In the experiment on eel substratum selection, 40% of the eels passed in lanes with studded substratum, whereas only 21 and 5% passed using open weave and bristle substrata respectively. Video analysis revealed that the studded substratum attracted more approaches and initiated climbs than the other substrata, but once a climb had been initiated, passage success rates did not differ between substrata. Eels using the studded substratum climbed 26% faster than those using the bristle substratum and almost four times as fast as those climbing in the open weave. The superior performance of the studded substratum was supported by data from the field validation. Moreover, ramps positioned by the bank with low water velocities caught the most eels, but proximity to the dam had no effect on performance. To strengthen the European eel population, more juveniles need to reach their freshwater feeding grounds. A critical step to achieve this increase is to equip upstream passage solutions with suitable substrata and to optimize ramp placement at migration obstacles.”

Access the paper here, or contact any of the authors.

Raft spider (Dolomedes sp.)

A PhD position in biology (community and food web ecology) is now open for application at Karlstad University. The project will focus on evaluating the ability of forested buffer strips to maintain cross boundaries fluxes between streams and riparian ecosystems.

The aim of the PhD project is to (i) analyse the link between riparian forest buffer width and functional diversity of riparian predator communities, (ii) define optimal buffer zones for conservation of riparian ecosystem functions, based on food web complexity and ecological niches (using stable isotopes) and (iii) use DNA-barcoding to study variation in prey preference with varying buffer width and test stable isotopes as a tool to assess riparian ecosystem functions in forestry affected landscapes.

The position is full time for four years but may be extended if department duties such as teaching (maximum 20 % of a full-time position) are included.

Last application date is 14 March 2019.

Read more and apply for the position here!

 

River Mörrumsån, Sweden