Calluna AB

Stockholm, Sweden

Calluna AB

Stockholm, Sweden
SEARCH FILTERS
Time filter
Source Type

Alatalo J.M.,Qatar University | Jagerbrand A.K.,Calluna AB | Chen S.,Chengdu University of Technology | Molau U.,Gothenburg University
Annals of Botany | Year: 2017

Background and Aims Climate change is expected to have major impacts on high alpine and arctic ecosystems in the future, but empirical data on the impact of long-term warming on lichen diversity and richness are sparse. This study report the effects of 18 years of ambient and experimental warming on lichens and vascular plant cover in two alpine plant communities, a dry heath with sparse canopy cover (54 %) and a mesic meadow with a more developed (67 %) canopy cover, in sub-arctic Sweden. Methods The effects of long-term passive experimental warming using open top chambers (OTCs) on lichens and total vascular plant cover, and the impact of plant cover on lichen community parameters, were analysed. Key Results Between 1993 and 2013, mean annual temperature increased about 2 °C. Both site and experimental warming had a significant effect on cover, species richness, effective number of species evenness of lichens, and total plant canopy cover. Lichen cover increased in the heath under ambient conditions, and remained more stable under experimental warming. The negative effect on species richness and effective number of species was driven by a decrease in lichens under experimental warming in the meadow. Lichen cover, species richness, effective number of species evenness were negatively correlated with plant canopy cover. There was a significant negative impact on one species and a non-significant tendency of lower abundance of the most common species in response to experimental warming. Conclusions The results from the long-term warming study imply that arctic and high alpine lichen communities are likely to be negatively affected by climate change and an increase in plant canopy cover. Both biotic and abiotic factors are thus important for future impacts of climate change on lichens. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.


Andersson P.,Calluna AB | Koffman A.,Calluna AB | Sjodin N.E.,U.S. Environmental Protection Agency | Johansson V.,Calluna AB | Johansson V.,Swedish University of Agricultural Sciences
Nature Conservation | Year: 2017

Roads may act as barriers to animal movements, but direct barrier effects on insects have rarely been studied. In this study we collected data on bees and wasps along two sides of a large road in Sweden using yellow pan traps. We then analyzed if the species composition differed between the two sides of the road; first for the whole community, and then only for the smallest species (which typically are poorer dispersers). As a complement, we analyzed if different vegetation variables differed between the two sides of the road, as this may also affect differences in species composition. Finally, we analyzed if species richness and abundance in general differed between the two sides and how these two response variables were explained by the vegetation variables. There was a significant difference in species composition between the eastern and the western side of the road when analyzing the whole community, and this relationship became even stronger when the largest species were excluded. The vegetation variables did not strongly differ between the two sides, and there was no difference in species richness and abundance of bees and wasps either. Abundance was, however, explained by the number of flowering plants in the surroundings of the trap. Even though using a rather limited data set, our results indicate that large roads may act as barriers on the movement of bees and wasps, especially for small species with poor dispersal ability. On the other hand, road verges may be important habitat for many species, which leads to a potential conflict that is important to consider in the planning of green infrastructure. © P. Andersson et al.


Almen A.-K.,Åbo Akademi University | Almen A.-K.,Novia University of Applied Sciences | Brutemark A.,Novia University of Applied Sciences | Brutemark A.,University of Helsinki | And 4 more authors.
Hydrobiologia | Year: 2017

Ocean acidification can impair an animal’s physiological performance and energetically demanding activities such as swimming. Behavioural abnormalities and changed activity in response to ocean acidification are reported in fish and crustacean species. We studied swimming activity in the calanoid copepod Pseudocalanus acuspes in response to near-future ocean acidification. Water and copepods were sampled from ten mesocosms deployed on the Swedish west coast. The experiments were conducted on animals reared in the mesocosms for 2 months during spring. Copepods were filmed after long-term (chronic) high-CO2, and after 20 h acute exposure to CO2. There was no significant effect of CO2 on copepods in chronic high-CO2, nor significant effect after the 20 h acute exposure. In addition, we measured prosome length from a large number of adult copepods, but no effect of acidification on body size was found. In this study, P. acuspes did not show sensitivity to near-future pCO2 levels. Even if a number of papers suggest that copepods seem robust to future ocean acidification, interaction between multiple stress factors, such as elevated temperature, hypoxia and salinity changes may impair a copepod’s ability to resist lowered pH. © 2017 Springer International Publishing AG


News Article | September 23, 2016
Site: www.sciencenews.org

A summertime cold snap can, quite literally, take the bloom off the rose. Not so for Scotch heather — and now scientists know why. Thick cell walls and narrow plumbing in the alpine shrub’s stems stop deadly ice crystals from spreading to its fragile flowers during sudden summer freezes, researchers report September 15 in PLOS ONE. That lets the flowers survive and the plant make seeds even if temperatures dip below freezing. Once ice crystals start to form inside of a plant, they can spread very quickly, says Gilbert Neuner, a botanist at the University of Innsbruck in Austria who led the study. Those sharp crystals can destroy plant cells — and flowers are particularly sensitive. So plants living in cold climes have developed strategies to confine ice damage to less harmful spots. Neuner and his team used infrared imaging to measure heat given off by Scotch heather (Calluna vulgaris) plants as they freeze. That technique revealed where and when ice was forming. And looking at thin slices of the plant under a microscope let the scientists pick apart the structure of the plant’s ice barrier. Cells at the base of the flower stalks had thicker walls and were packed more closely together than elsewhere in the plant, the team found. In the same area, the pipelines that carry water up the plant — called xylem — were narrower and had fewer points where ice could potentially sneak through. Those modifications let the plants “supercool” their flowers. That is, even when the flowers chilled to below zero degrees Celsius, they contained liquid water instead of ice. Ice didn’t form in the Scotch heather flowers until far below normal freezing temperatures, ‒22° C, and ice that formed elsewhere in the plant didn’t spread to the flowers. Other species sometimes put up temporary ice blockades, for instance to protect overwintering buds. But that usually cuts off the flow of water through the xylem — fine if a plant is dormant over the winter, but flowers facing a sudden summer freeze need a continuous supply of water. Scotch heather gets around this problem by threading its xylem right through the icy barrier. Membranes let water pass between the xylem cells, and these membranes might ultimately control the spread of ice crystals in C. vulgaris, Neuner suspects. Tiny pores in the membranes are too small to let ice crystals through the barrier. And when water molecules are found inside such small holes, the molecules are bound so tightly to the structures around them that they behave more like a gel instead of crystalizing into ice. The team hopes to test the idea in future studies. Other flowering alpine plants could use a similar strategy. “I don’t think that this is unique to this plant,” says Sanna Sevanto, a tree physiologist at Los Alamos National Laboratory in New Mexico who wasn’t involved in the study. “It’s just that nobody has looked at it.”


Hogfors H.,University of Stockholm | Hogfors H.,AquaBiota Water Research | Motwani N.H.,University of Stockholm | Hajdu S.,University of Stockholm | And 8 more authors.
PLoS ONE | Year: 2014

It is commonly accepted that summer cyanobacterial blooms cannot be efficiently utilized by grazers due to low nutritional quality and production of toxins; however the evidence for such effects in situ is often contradictory. Using field and experimental observations on Baltic copepods and bloom-forming diazotrophic filamentous cyanobacteria, we show that cyanobacteria may in fact support zooplankton production during summer. To highlight this side of zooplanktoncyanobacteria interactions, we conducted: (1) a field survey investigating linkages between cyanobacteria, reproduction and growth indices in the copepod Acartia tonsa; (2) an experiment testing relationships between ingestion of the cyanobacterium Nodularia spumigena (measured by molecular diet analysis) and organismal responses (oxidative balance, reproduction and development) in the copepod A. bifilosa; and (3) an analysis of long term (1999-2009) data testing relationships between cyanobacteria and growth indices in nauplii of the copepods, Acartia spp. and Eurytemora affinis, in a coastal area of the northern Baltic proper. In the field survey, N. spumigena had positive effects on copepod egg production and egg viability, effectively increasing their viable egg production. By contrast, Aphanizomenon sp. showed a negative relationship with egg viability yet no significant effect on the viable egg production. In the experiment, ingestion of N. spumigena mixed with green algae Brachiomonas submarina had significant positive effects on copepod oxidative balance, egg viability and development of early nauplial stages, whereas egg production was negatively affected. Finally, the long term data analysis identified cyanobacteria as a significant positive predictor for the nauplial growth in Acartia spp. and E. affinis. Taken together, these results suggest that bloom forming diazotrophic cyanobacteria contribute to feeding and reproduction of zooplankton during summer and create a favorable growth environment for the copepod nauplii. © 2014 Hogfors et al.


Vehmaa A.,Novia University of Applied Sciences | Vehmaa A.,University of Helsinki | Hogfors H.,University of Stockholm | Gorokhova E.,University of Stockholm | And 5 more authors.
Ecology and Evolution | Year: 2013

Zooplankton are an important link between primary producers and fish. Therefore, it is crucial to address their responses when predicting effects of climate change on pelagic ecosystems. For realistic community-level predictions, several biotic and abiotic climate-related variables should be examined in combination. We studied the combined effects of ocean acidification and global warming predicted for year 2100 with toxic cyanobacteria on the calanoid copepod, Acartia bifilosa. Acidification together with higher temperature reduced copepod antioxidant capacity. Higher temperature also decreased egg viability, nauplii development, and oxidative status. Exposure to cyanobacteria and its toxin had a negative effect on egg production but, a positive effect on oxidative status and egg viability, giving no net effects on viable egg production. Additionally, nauplii development was enhanced by the presence of cyanobacteria, which partially alleviated the otherwise negative effects of increased temperature and decreased pH on the copepod recruitment. The interactive effects of temperature, acidification, and cyanobacteria on copepods highlight the importance of testing combined effects of climate-related factors when predicting biological responses. The combined effects of ocean acidification and global warming predicted for year 2100 with toxic cyanobacteria are studied on the calanoid copepod, Acartia bifilosa. As zooplankton are an important link between primary producers and fish, it is crucial to address their responses when predicting effects of climate change on pelagic ecosystems. The found interactive effects of temperature, acidification, and cyanobacteria highlight the importance of testing joint effects of climate-related factors when predicting biological responses. © 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.


PubMed | Novia University of Applied Sciences, Calluna AB, IMDEA Madrid Institute for Advanced Studies and University of Stockholm
Type: Journal Article | Journal: PloS one | Year: 2014

It is commonly accepted that summer cyanobacterial blooms cannot be efficiently utilized by grazers due to low nutritional quality and production of toxins; however the evidence for such effects in situ is often contradictory. Using field and experimental observations on Baltic copepods and bloom-forming diazotrophic filamentous cyanobacteria, we show that cyanobacteria may in fact support zooplankton production during summer. To highlight this side of zooplankton-cyanobacteria interactions, we conducted: (1) a field survey investigating linkages between cyanobacteria, reproduction and growth indices in the copepod Acartia tonsa; (2) an experiment testing relationships between ingestion of the cyanobacterium Nodularia spumigena (measured by molecular diet analysis) and organismal responses (oxidative balance, reproduction and development) in the copepod A. bifilosa; and (3) an analysis of long term (1999-2009) data testing relationships between cyanobacteria and growth indices in nauplii of the copepods, Acartia spp. and Eurytemora affinis, in a coastal area of the northern Baltic proper. In the field survey, N. spumigena had positive effects on copepod egg production and egg viability, effectively increasing their viable egg production. By contrast, Aphanizomenon sp. showed a negative relationship with egg viability yet no significant effect on the viable egg production. In the experiment, ingestion of N. spumigena mixed with green algae Brachiomonas submarina had significant positive effects on copepod oxidative balance, egg viability and development of early nauplial stages, whereas egg production was negatively affected. Finally, the long term data analysis identified cyanobacteria as a significant positive predictor for the nauplial growth in Acartia spp. and E. affinis. Taken together, these results suggest that bloom forming diazotrophic cyanobacteria contribute to feeding and reproduction of zooplankton during summer and create a favorable growth environment for the copepod nauplii.


Helldin J.-O.,Calluna AB | Wissman J.,Swedish University of Agricultural Sciences | Lennartsson T.,Swedish University of Agricultural Sciences
Nature Conservation | Year: 2015

Road and railroad verges may contribute to nature conservation by providing habitat for many species, but due to limited resources, there is a need to select the most important road and railroad stretches for adapted management. We explore the responsibility species concept as a tool for the Swedish Transport Administration to make this selection. We propose lists of candidate responsibility species based on relative abundance of conservation priority species in the vicinity of roads and railroads, respectively. Abundance data were derived from crowd-sourced species observations. Species with ≥20% of observations in infrastructure habitats were included as candidate responsibility species. For roads 32 species were included in the list, for railroads seven species, with an overlap of three species between the lists. We analyzed habitat and management requirements of the listed species to try identifying functional groups. Most of the species require open or semi-open habitats, mainly dry grassland or heathland on sandy or limy soil, un-sprayed crop fields, or solitary trees. Host plants or substrates include broom (genus Genista), patches of bare soil, and sun exposed wood. Conservation actions prescribed for the species include, e.g., late or irregular mowing, removal of the field layer, planting of host species, protecting and providing particular substrates, and special protection of certain sites. We argue that road and railroad managers are particularly well suited to conduct most of these actions. We consider the responsibility species concept to be a useful tool for transportation agencies to set priorities for adapted verge management, and the current method to be effective in identifying a first list of candidate species. We discuss the possibility of also identifying responsibility habitats or general management measures based on the results. Copyright Jan-Olof Helldin et al.


Holliland P.B.,University of Stockholm | Holmborn T.,Calluna Ab | Gorokhova E.,University of Stockholm
Journal of Plankton Research | Year: 2012

In the Baltic Sea, the predatory cladoceran Cercopagis pengoi is a non-indigenous species that has potential to compete for mesozooplankton with pelagic zooplanktivorous fish. To understand the extent of diet overlap with these fishes in a coastal area of the northern Baltic proper, we studied the feeding of C. pengoi using stable 13C and 15N isotope signatures of the predator and possible prey. Feasible combinations of sources were estimated in two ways: (i) with the IsoSource mixing model, and (ii) temporal-tracking analysis. Further, contribution of different prey was related to ambient zooplankton composition to gauge selectivity. The modelling results indicate that C. pengoi is an opportunistic generalist predator with a positive selection towards older copepodites (CIVVI) of Acartia spp. and Eurytemora affinis, which also have the greatest contribution to its diet. Positive selection towards podonid Cladocera is also likely. In contrast, evidence for extensive feeding on microzooplankton was inconclusive, and bosminids were not found to be an important prey in the zooplankton assemblages studied. As the derived diet of C. pengoi overlaps greatly with that of zooplanktivorous fish, food competition between these zooplanktivores is possible. © 2012 The Author. Published by Oxford University Press. All rights reserved.


News Article | November 21, 2016
Site: www.theguardian.com

Old Bottom, as the Marshwood Vale was once called, has filled with autumn rain. Walking means slogging, ankle deep or more, through cold, claggy clay, navigating puddles of yellow water overhung with dripping trees. Time to escape the woods for higher, drier ground. Hardown Hill is one of a circle of hills and forts ringing the vale. Steep sides of deciduous woodland and gaps of rough pasture run up to a flat top of heath where nightjars call in summer. The summit is open, unfenced common land, home to sand lizards and occasionally Dartford warblers. Villagers used to cut the heath for fuel. Gorse was particularly prized in bread ovens because it burned quick and hot before disintegrating into an insignificant pile of fine ash. In Dorset dialect, gorse was furze, pronounced “vurze”, just as fox was “varx”. I walk clockwise into the low sun shining sharp across the heath. Long wires of purple moor grass gleam metallically and the last few gold leaves on a silver birch flutter like tinsel against the hard blue sky. It’s raining in Devon out to the west, and the far hills are smoky purple under cloud shadow. North east lies Rogue Male country, where the unnamed hero of Geoffrey Household’s classic thriller literally went to ground, burying himself in the damp tree roots of an old hollow way. I skirt the old quarry workings, swamped in spring with bluebells and now swathed with rusty bracken. A last cricket chirps slowly like a smoke alarm with a near exhausted battery. The sea dazzles through a sudden gap and the sea-swell sound of traffic on the A35 washes up from below. Due east, the long, thin wedge of Portland floats impossibly high on the horizon. Heading back west over the crest of the hill, I face the brunt of the wind, which rattles the heather. Three species grow here: ling (Calluna vulgaris), bell heather (Erica cinerea) and cross-leaved heath (Erica tetralix.) The rain has caught up with me and a rainbow appears, arcing over the hill. I turn away and walk on; when I look back it’s gone, switched off abruptly as the shower moves east.

Loading Calluna AB collaborators
Loading Calluna AB collaborators