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  • 1.
    Lind, Johan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Jöngren, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Nilsson, Jenny
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Schönberg Alm, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Strandmark, Alma
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Information, predation risk and foraging decisions during mobbing in great tits, Parus major2005Inngår i: Ornis Fennica, ISSN 0030-5685, Vol. 82, s. 89-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tomaximise survival during foraging animalsmust decide when and for how long foraging should be interrupted in order to avoid predators. Previous experiments have shown that birds that hear other individuals’alarm calls resume feeding later than those that see a flying predator.However, the responses of prey animals to enemies are highly context-dependent. We therefore investigated how birds respond to a threat less serious than a flying hawk depending on different amount of information about the predator. We used Great Tits dyadswhere one individual saw a perchedmodel predator (sender), whereas the other individual could only hear the conspecific’s mobbing calls (receiver). The sender responded appropriately as shown by comparing their responses to how they responded to a control.We also found that while senders were exposed to the predator, receivers became more wary and reduced their activity level. However, despite the receivers having less information about predation risk they still did not prolong the time they took to resume foraging. Hence, once the mobbing ceased (and consequently the transmission of information about the predator stopped) therewas no effect of only having second-hand information. This also shows that receiver’s rely upon the sender’smobbing calls suggesting that mobbing calls may act as honest signals of the prevailing predation risk. In conclusion, our results support the view that responses of prey to predators are highly context-dependent and that birds’ anti-predator responses are a result of an interaction between the amount of information and the level of the threat.

  • 2.
    Strandmark, Alma
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Baltic Sea shores and climate change2014Rapport (Annet vitenskapelig)
    Abstract [en]

    The Baltic Sea is a brackish semi-enclosed water volume with a pronounced latitudinal gradient in salinity and temperature. Climate change projections for the Baltic Sea ecosystem include; increased water temperatures, increased eutrophication, increased occurrence of cyanobacteria blooms and a probable change in salinity. Higher water temperature will increase the metabolic rate of plants and animals which, together with eutrophication, will benefit fast growing, filamentous algae and thereby cause a reduction in the population of the important species bladderwrack (Fucus vesiculosus).

    The coast around the Baltic Sea is heavily exploited by humans, especially the sheltered, shallow areas where shore meadows are usually found. Since human structures and buildings will also be affected by a sea level rise, there might be an intensified conflict between human interests and conservation of coastal habitats in the future. Terrestrial shoreline habitats in the Baltic Sea show large geographic differences but species rich shore meadows are present everywhere along the coastline. The Baltic Sea region is under the influence of the last ice age with isostatic rebound still causing land uplift in the northern and central parts of the area. Climate change is constantly moving the equilibrium line between isostatic rebound and sea level rise northwards. Since many species in shoreline ecosystems depend on that new land continuously rise from the sea the composition of species will likely change radically due to rising sea levels. Further, a decrease in sea ice cover together with increased wind speeds during winter might enhance the ice scouring and disturbance in coastal habitats in the northern Baltic Sea. At the same time the management (grazing and hey making) of shore meadows along the Baltic shoreline has almost stopped which has decreased the diversity of plants and insects. The lack of management together with climate change and further fragmentation of valuable habitats will probably produce ecosystems that in the future will be dominated by relatively few generalist species.

    Fulltekst (pdf)
    fulltext
  • 3.
    Strandmark, Alma
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Baltic shore-lands facing climate change2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis provides new insight concerning drivers behind differences in arthropod diversity and abundance in Baltic shore ecosystems and how the arthropod communities might be affected when the conditions in the Baltic Sea are altered due to climate change.  The focus has been on climate related changes that are unique for coastal ecosystems, especially sea level rise and changes in the inflow of marine nutrients.

    As sea levels rise, features in coastal landscapes will be altered, islands and habitats will be flooded and diminished, and structural connectivity within the island landscape will therefore change. This thesis shows that arthropod diversity within the two arthropod groups, spiders and beetles, increases with island size but also that diversity is positively influenced by a high number of islands in the surroundings.

    A changed distribution and occurrence of marine species, due to climate change or eutrophication, can also affect terrestrial organisms on the shore.  In the Baltic Sea the new conditions following climate change will decrease the prevalence of bladder-wrack and benefit filamentous algae. Algal deposits on shores reflect the marine species composition and a decreased prevalence of bladder-wrack in the Baltic Sea will also be visible on the shores.  This thesis shows that a lower proportion of bladder-wrack in the algal deposits will decrease the diversity and abundance of arthropods in these deposits.

    Changes in the marine environment may also affect the inflow of insects with aquatic life stages and terrestrial adult stages.  On Baltic shores, prey species with aquatic life stages, especially chironomids, constitute a large proportion of the diet of the terrestrial predatory group, wolf spiders. In freshwater system, the inflow of chironomids is known to decrease with elevated water temperatures if this is true in the Baltic Sea prey availability of wolf spiders would decrease.  This thesis supports the importance of chironomids as a prey for coastal wolf spiders, but also shows that the diet varies over season with dominance of terrestrial prey in early summer shifting to a dominance of marine prey in late summer and autumn. This seasonal variation is primarily due to a gradual increase in the consumption of chironomids over season.

    Climate change has the potential to alter the biogeographical conditions in coastal landscapes as well as the density and quality of marine nutrient inflow. Sea level rise will diminish and flood islands and this thesis shows that a moderate sea level rise of 0.5 meters would make the total number of islands in the outer part of Stockholm archipelago decrease with about 25 %. Sea level rise could thus have consequences for arthropod diversity in Baltic shore meadows in the near future. The combined effects of sea level rise and changed prevalence of marine species in the Baltic Sea will affect the abundance and diversity of arthropods substantially. The abundance and diversity of spiders and beetles will decrease on shores that today have a high occurrence of bladder-wrack and prey availability for coastal predators might decrease due to a decreased inflow of chironomids. Changes in the arthropod communities could have consequences also further up in the food chain, such as for shore birds feeding on these arthropods.

    Fulltekst (pdf)
    Baltic shore-lands facing climate change
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  • 4.
    Strandmark, Alma
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Aggemyr, Elsa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Drivers behind local and regional arhropod diversity in naturally fragmented landscapesManuskript (preprint) (Annet vitenskapelig)
  • 5.
    Strandmark, Alma
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Bring, Arvid
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Kautsky, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Kolb, Gundula
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    de la Torre-Castro, Maricela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Climate change effects on the Baltic Sea borderland between land and sea2015Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, s. s28-S38Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Coastal habitats are situated on the border between land and sea, and ecosystem structure and functioning is influenced by both marine and terrestrial processes. Despite this, most scientific studies and monitoring are conducted either with a terrestrial or an aquatic focus. To address issues concerning climate change impacts in coastal areas, a cross-ecosystem approach is necessary. Since habitats along the Baltic coastlines vary in hydrology, natural geography, and ecology, climate change projections for Baltic shore ecosystems are bound to be highly speculative. Societal responses to climate change in the Baltic coastal ecosystems should have an ecosystem approach and match the biophysical realities of the Baltic Sea area. Knowledge about ecosystem processes and their responses to a changing climate should be integrated within the decision process, both locally and nationally, in order to increase the awareness of, and to prepare for climate change impacts in coastal areas of the Baltic Sea.

  • 6.
    Strandmark, Alma
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Verschut, Vasiliki
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Esparza Salas, Rodrigo
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Seasonally varying marine influences on the coastal ecosystem detected through molecular gut content analysis but not through stable isotope analyisManuskript (preprint) (Annet vitenskapelig)
  • 7.
    Strandmark, Alma
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Vicente, Raul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    The structure of marine deposits affectes arthropod communities in southern Baltic shore ecosystemsManuskript (preprint) (Annet vitenskapelig)
  • 8.
    Verschut, Vasiliki
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Strandmark, Alma
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Esparza-Salas, Rodrigo
    Hambäck, Peter A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Seasonally varying marine influences on the coastal ecosystem detected through molecular gut analysis2019Inngår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 28, nr 2, s. 307-317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Terrestrial predators on marine shores benefit from the inflow of organisms and matter from the marine ecosystem, often causing very high predator densities and indirectly affecting the abundance of other prey species on shores. This indirect effect may be particularly strong if predators shift diets between seasons. We therefore quantified the seasonal variation in diet of two wolf spider species that dominate the shoreline predator community, using molecular gut content analyses with general primers to detect the full prey range. Across the season, spider diets changed, with predominantly terrestrial prey from May until July and predominantly marine prey (mainly chironomids) from August until October. This pattern coincided with a change in the spider age and size structure, and prey abundance data and resource selection analyses suggest that the higher consumption of chironomids during autumn is due to an ontogenetic diet shift rather than to variation in prey abundance. The analyses suggested that small dipterans with a weak flight capacity, such as Chironomidae, Sphaeroceridae, Scatopsidae and Ephydridae, were overrepresented in the gut of small juvenile spiders during autumn, whereas larger, more robust prey, such as Lepidoptera, Anthomyidae and Dolichopodidae, were overrepresented in the diet of adult spiders during spring. The effect of the inflow may be that the survival and growth of juvenile spiders is higher in areas with high chironomid abundances, leading to higher densities of adult spiders and higher predation rates on the terrestrial prey next spring.

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