No, more wetlands will not lead to malaria epidemics in Sweden!

The risk of getting back malaria in Sweden is sometimes suggested as a real concern in discussions regarding large state-funded efforts to re-create wetlands to mitigate climate change or reduce eutrophication and increase landscape biodiversity. The latest we have found regarding this is from a magazine published by Derome where a professor in history, Kalle Bäck, calls the risk of malaria a “terrible consequence that nature conservationists have missed”, see attached article (in Swedish). The problem is that he is completely wrong.

Anders Lindström at SVA, the National Veterinary Institute states:

“It is a strange statement about malaria that Kalle Bäck makes. Firstly, it can be stated that the malaria that existed in Sweden in the 18th and 19th centuries was caused by Plasmodium vivax. The parasite that Bäck refers to as causing the most deaths in the world is Plasmodium falciparum, that is, a completely different species. P. falciparum has never been found in northern Europe because it is too cold here for the parasite to develop in the mosquitoes. Plasmodium vivax can certainly also kill infected humans, but to a much lesser degree. During the period 1749 – 1820 an average of 1045 people died per year from malaria in Sweden. The disease was endemic and common along the coast from Blekinge up to Ångermanland and around Mälaren and Vänern. When there were epidemic outbreaks, it appeared all over southern Sweden.

The species of malaria mosquitoes responsible for the spread of malaria parasites overwinter as fully grown female mosquitoes. You can still visit almost any stable attic and find malaria mosquitoes. The dredging of wetlands certainly reduced the population of malaria mosquitoes, but as I said, the mosquitoes are still there and are not rare.

The fact that malaria disappeared in Sweden is considered mainly to be due to better housing standards. The mosquitoes thrive in dark and damp stables. When the housing standard was lower, there was no major difference between animal houses and residential houses. Often the animals were outdoors all year round. When the houses became warmer, brighter, cleaner and with lower humidity than before, the mosquitoes preferred to stay in the increasingly common animal stables. Since malaria mosquitoes almost always bite at night and there is food for them in the stables, fewer people were bitten and the transmission of malaria parasites decreased until it stopped.

The improved health care and the use of quinine also reduced malaria parasites. In order for us to bring back malaria in Sweden, it would be required that we get a significant part of the population infected by malaria parasites and at the same time bring back the 18th century housing standard and that the healthcare system fails to identify and treat malaria cases. “

Project dissemination is on-going

We frequently have visits by landowners, authorities and researchers to workshops, meetings and excursions where we present our activities. Latest examples include a delegation from Latvia (IP LIFE-Goodwater) during a 3-day visit where we had good discussions and visited several of the Buffer project wetlands, and a presentation of the Buffer project by Sofia for participants at the WWF networking meeting in the Baltic Stewardship Initiative.

Excursion at the WWF networking meeting 29 of September 2022
Presentation of the Buffer project to the Lativan delegation at one of our project wetlands the 20 September 2022

New arthropod sampling this week

This week Peter and assistant biology student Ellen Nein are doing a new sampling campaign in the 8 wetlands that were emptied this summer and the 8 controll wetlands. This follow-up sampling will also be repeated next year to study more long-term effects of droughts on the arthropod communities in the floodzones of wetlands.

Vegetations survey gave interesting botanical results

The vegetation surveys of ca 25 wetlands are now finished. In total ca 15 submersed species were found, including at least 4 Charophyte species. Among the more interesting findings were the Bryozoa Plumatella repens and 2 Nitella species that are on the Redlist (NT); N. gracilis and N. mucronata. Unfortunately we also found the invasive species Elodea nutallii in some wetlands. Below are some photos of some species. It is clear that constructed wetlands in the agricultural landscape can be important also for threathened and rare plant species, and the the occurrence of invasive species is frequent.

Plumatella repens
Elodea nutallii

Vegetation surveys started

We have started with the surveys of submersed vegetation in the wetlands. This is also part of our networking with the Cyano bacteria project at Lund University run by Pablo Pablo Urrutia Cordero. The macrophytes are surveyed every 10 meters at 2 transects perpendicular to each other in each wetland. It is always interesting to see how the planning (first photo) holds up when it meets the reality of the field work (second photo)…So far so good, Our idea with two persons on the SUP where one handles the GPS to find the right sampling site and does steering and paddling, and one person doing the actual sampling seems to work.

Second sampling in the field experiment

This week David is in Halland to do the follow up-sampling in the field experiment where we have emptied 8 wetlands. He had help from an Intern from the biology course at Stockholm University, Beata Wolgers. Some maintanence of one of the Malais trap was also neccessary since the cattle can be a bit too curious.

Field experiment started (water level manipulations)

This week we started a field experiment where we simulate drought by emptying (lowering the water table) some wetlands. We emptied 8 wetlands and have another 8 as controls. The purpose is to see the effect of drought on the arthropod communities at the shorelines of the wetlands. Peter did the ”pre-drought” sampling with Malaise traps, color bowls, suction sampling and pitfall traps. We also took photos of the wetlands with a drone before and after emptying. After a month of dry-out we will repeat the invertebrate sampling, and also repeat it next year to study long-term effects.

Presentation of Dragonfly data att ECOO 2022, Slovenia

Presentation of Dragonfly data att ECOO 2022, Slovenia

John presented some data from the dragonfly surveys at ECOO 2022 (European Congress on Odonata) in Slovenia, the 26-30 of June. It was a nice conference with lots of discussions on dragonflies (of course). Dragonfly researchers from 25 countries participated and apart from interesting presentations we also were on a field trip to see slovenian dragonflies with specialities such as Coenagrion ornatum and Cordulegaster hero.

Scientific paper published

The first paper from our surveys is now published. The title is: Insects and spiders in constructed wetlands: interesting findings from a systematic survey in Uppland and southern Halland, and is published in Entomologisk Tidskrift 143 (1–2): 47–66. It can be viewed and downloaded by clicking on the image below:

SEPA`s annual meeting on Wetland ecosystem services held at Halland

The annual meeting for the Swedish Environmental Protection Agency´s research grants on Wetland ecosystem services was held att Hushållningssällskapet Halland/LIFE-Goodstream the 17-18 of March. It was a hybrid meeting with ca 25 persons on site and ca 45 joining digitally. It was a very nice meeting (despite the weather during the field day) and we visited Halmstad University´s experimental set-up aswell as some of our sites in the Buffer project. All the 8 projects presented their work and we got oppertunities to good discussions and networking during the meeting.

New Publication in Wetlands 2.0

This week a paper on trophic cascades involving fish, zooplankton, phytoplankton, algal mats, bumle bees and oil seed rape, in a mesocosm experiment conducted in the project, was publishen i OIKOS

The results also have implications for the Buffer project regarding e.g. polinator behaviour during droughts and under different nutrient status of the wetlands.

Our results on national radio (”Vetenskapsradion”)

Today, some results from our survey to landowners were in the ”science news” segment on Swedish national radio. It was the fact that the most common use of the constructed wetlands, by the landowners, was skating. Almost 40 % of the landowners we interviewed stated that they used the wetlands for skating. The short news segment can be heard here (in swedish):

Popular scientific article submitted

Today we submitted a short article to inspire the public to explore wetland shorelines in order to experience the high biodiversity of insects and spiders. It is based on the findings in our projects which also are explained in the article. Results on beetles, spiders, flies, dragonflies and pollinators are presented. It will be published in ”Hallands Natur” (in Swedish).

Mainenance of water level meters continues…

As always with electronic equipment permanently deployed in the field there is some wear and tear. Here is a meter where the cable has been disconected, possibly beacause of movements of the ice. Sofia and Sam exchange batteries and repair the ones that malfunction continously.

”Half-time” Thesis presentation by David Åhlén

The 19 of November David Åhlén presented results from the Buffer project and the Management project as part of his ”half-time” seminar in his thesis-work at Stockholm University. Opponent was Professor Riccardo Bommarco, SLU. It was a combined live and zoom event and we got to hear interesting discussions on invertebrate food web dynamics at wetland shorelines/flood zones, and effect of management regimes on species abundance and distribution.

A paper on interesting findings from the biodiversity surveys of 2020-2021 has been submitted

Today we submitted the first scientific paper in the project. It is a compilation with commentaries on interesting findings from the biodiversity sampling. It was submitted to the Swedish Entomological Society´s Journal; ”Entomologisk tidskrift”. The title is: ”Insekter och spindlar i anlagda våtmarker: Intressanta fynd från en systematisk undersökning i Uppland och södra Halland” (Insects and spiders in constructed wetlands: Interesting findings from a systematic survey in Uppland and southern Halland).

Conference and work shop in Stockholm

The whole Biowetland project group attended a conference at Stockholm University (Multi-functional wetlands) the 27 of October and thereafter a 2-day workshop with ca 20 researchers discussing a joint paper on Constructed wetlands and synergies and trade-offs of wetland functions. A very good and rewarding 3-day event at Stockholm University and Tovetorp research station. Below are some photos from the conference and the workshop.

Second sampling of invertebrates for 2021

Today David arrived in Halmstad for sampling with Malaise traps and pitfall traps in the 14 wetlands that we will empty next year. This sampling toghether with another sampling next year before emptying will serve as comparisons with samplings done after the lowering of the water levels.

David loads the car with Malaise-traps and other field equipment at our office.

Filming of our project again

Today Johan and Joel from Heurgren Film AB spent a day in Halland to film our activities in the buffer project and also visiting researchers Pia and Joachim from projekt WetKit. The film is produced as part of project WetKit.

New sampling period for Cyanoblooms

This week the second field sampling was done in 80 of ”our” buffer wetlands to investigate occurence of Cyano algae and cyano toxin, as part of our networking collaboration with Pablo Urrutia Cordero at Lund univiserity. This time it was Sam (working for Pablo) who did the field work.

Project WetKit visit Halland

This week Pia and Joachim from project WetKit have been in Halland for fieldwork in ”our” wetlands. Colaboration is always rewarding and we hade good discussions on methods and the state of the wetlands. Pia and Joachim sampled sediment cores in 19 of the wetlands.

Field experiments with pollinators finished – emptying of wetlands postponed to next year

The field material (various traps nests and nest boxes) from the pollinator field experiments that now have been terminated, have been collected and stored. Due to the very high rainfall in August we could not carry out the planned test with effects of draining some of the wetlands. We have however got permission from the landowners so we will do it next year (weather permitting). This experiment (emptying of ca 14 wetlands) is part of all 3 projects (Wetlands as buffers, Management of wetlands and Wetlands 2.0) and will hopefully give answers to different research quesitons in the three projects.

First flow measurments are done

We have now done the first flow measurements in the 11 streams at the same segments where we have the flowmeters located. These first measurements were done at low flow situations (low water levels), and we will repeat this under medium and high flows also, to get good data on the flow at different water levels. Then we get data on flow with 1 hours resolution by combining the flow measure data with the water level data. The photos show some of the field work in the different streams.

We expand our surveys to include selected invasive species

We have added a categroy to our field protocols. When we are surveying the 112 wetlands (batymetry, dragonflies, invertebrates etc) we now also check for selected invasive species. We have selected ca 10 species that are easily recognized and invasive, in order to get data on the occurrence of invasive species in constrcted wetlands in the agricultural landscape. It was not planned in the proposal, but our field surveys give us a good opertunity to get useful data on a large set of constructed wetlands as a side-effect. The species we check for are e.g. Nuttalls Pondweed + Canadian pondweed (Elodea canadensis + C. nutallii), Signal crayfish (Pacifastacus leniusculus), Red water lily (Nymphae alba, var. rocea) , Grass karp (Ctenopharyngodon idella), Yellow scunk cabbage (Lysichiton americanus), Himalyan balsam (Impatiens glandulifera), Japanese knotweed (Reynoutria japonica/Fallopia japonica), Giant hogweed (Heracleum mantegazzianum). The photo show signal crayfish in the wetland D31.

Canadian pondweed (Elodea canadensis) and Signal crayfish (Pacifastacus leniusculus) in the wetland D31

Bathymetry surveys continue

We continue with the time consuming work of depth profiling all the 112 wetlands. The wetlands vary quite a lot in terms of vegetation cover and water depth. The photo shows one of the more overgrown wetlands (KA5). In this wetland was also found Robust spreadwing (L. dryas) during the dragonfly survey.

Robust spreadwing at KA5

Some wetlands are dry at the moment – important habitat for adapted species

The dry weather has turned some wetlands into dry land. Theese extreme water level fluctuations are interesting for us to follow. Some species are adapted to theese habitats (shallow systems with occasional dryouts) and one example is the dragonfly Robust Spreadwing (Lestes dryas). The photos show the wetland ”D10” in the dry state and some specimen of Robust spreadwing found during our dragonfly survey in that wetland. This species is relatively rare in Halland and it is likely that constructed wetlands that dryout during summer is of major importance for the species. At our survey we found a quite large population of L. dryas at the site. Another species found at D10, with similar habitat requirements, was yellow-winged darter (Sympetrum flaveolum). It is also a rare species (likely to be included in the next update of the Redlist). For theese habitats, the management is especially important as they are sensitive for overgrowing with reeds and trees. D10 is grazed and mowed.

The wetland D10 in july 2021 showing our water level meter with the sensor on dry land during the drought.
A female Robust spreadwing (L .dryas)
A male Robust spreadwing (L .dryas)
A yellow-winged darter (Sympetrum flaveolum) also found of the survey of the wetland D10.

Drone photography has started

We have started with the drone to test how efficient it is to get reliable data on emergent vegetation cover. The actual pgotography will be done in late summer when vegetation is at its peak, but we tested the drone today.

Our activities in the Buffer project has been filmed

A professional film company (Heurgren Film AB) have spent two days following our work. In a project we network togwether with (WetKit) one part was to produce a film about constructed wetlands, and since we have several ongoing activities the film crew spent two days in Halland filming and interviewing us when we did our field work and discussed with the landowner.

3rd newsletter sent to landowners

Today we sent out the 3rd newsletter to the ca 8o landowenrs in the project with information about this years planned studies in their wetlands. Since we will take photos of all wetlands with a drone we also offered to send the pictures to the landowners if they wanted, which was quite popular.

Bathymetry measurements are ongoing

By combining sonar data that we get from paddling with a SUP and sonar in the open water, with high resolution GPS-measurements from the shoreline and in high and dense vegetation in shallow water we get very good data on the depth and shape och the wetlands. The photos shows Sofia paddling with a sonar (left) and the photo to the right shows the position of the water depth data points from the sonar (blue) and the water depth data points from the GPS (white) From this we can construct very detailed depths curves of the wetlands.

Testing bathymetry methods and flow measurement strategy

This week we had a 2-day meeting with Jerker Jarsjö and Imenne Åhlén (Stockholm University), to decide methods to produce bathymetric maps of the 110 wetlands and to finalise our strategy for flow measurements in the 11 streams in our joint project. It was a very productive meeting and the photos show equipment testing and part of the field work including trial with a remote-controlled boat with a sonar to map the wetland topography (bathymetry).

Sorting and identifying organisms continue…

The sorting work is progressing within the project with additional groups fully identified . The very large spider material is now identifed by Raul Vicente, and the dance flies (Empididae) by Sven Hellqvist. Examples from the two organism groups are shown below. Planning for this year’s studies is also in full swing. As we have received funding for nutrient analyzes in Uppland from Bolincentret’s RA3 and RA7, as well as the Albert and Maria Bergström Foundation, we will be able to collect very interesting data to investigate the impact of nutrients on spider and insect communities. We have also received funding for a drought experiment in Halland from Bolincentret’s RA8, and it will be very interesting to see how drought affects spiders’ condition and food preferences.

All the Crane flies (Tipuloidea) are now identified and counted

Another group of insects from the Malaise traps survey in 2020 has now been identified. it is the Crane flies, where we found a total of 47 species in Halland and 39 species in Uppland. Of these, 7 were new species for Halland and 4 new species for Uppland. The most exciting species was Paradelphomyia nigrina, which is a northern species and has only been found a few times in Finland and once each in Sweden (Dalarna) and Norway. The species was found in our traps in Uppland, and identified by Michael Andersson, Sweden’s leading expert on Crane flies. He has also taken the photo below

Tuvklotspindel (Rugathodes instabilis) – new species for Halland

The collection of invertebrates last summer continues to reveal interesting findings as the experts go through the material. The latest interesting discovery regarding species biogeographical data was the spider Rugathodes instabilis that was found in one of our wetlands in Halland (see photo below). It has only been found with a handfull individuals at 4 sites in the counties of Uppland, Östergötland and Skåne before, and now also Halland! For more info: