Algal community structure in artificial streams

In der vorliegenden Studie wurde die Algengemeinschaft auf künstlichen Fließrinnen, sogenannten Algal Turf Scrubbers (ATSs) untersucht. Die Studie wurde am Heustadelwasser, einem ehemaligen Donaualtarm, der sich im Prater in Wien befindet, durchgeführt. Die starke Eutrophierung des Gewässers erforderte die Errichtung einer Gewässerreinigungsanlage (Neptunanlage), welche den hohen Nährstoffgehalt des Gewässers und die damit einhergehenden, negativen Folgen reduzieren sollte. Die ATSs wurden an das bestehende Reinigungssystem angeschlossen um eine weitere Retention der Nährstoffe zu erzielen. Die Funktionsweise eines ATS ähnelt der Selbstreinigungsleistung von natürlichen Gewässern, da im Wasser befindliche Nährstoffe vom Biofilm aufgenommen und in die Biomasse eingebaut werden. Die auf den ATSs wachsende Algenbiomasse wurde regelmäßig abgeerntet und analysiert. Ziel der vorliegenden Studie war es, die Zusammensetzung der Algengemeinschaft zu charakterisieren, sowie die stattfindende Sukzession zu beschreiben. Weiters wurde untersucht, wie schnell die ATSs besiedelt werden und wie sich die Diversität der Algen im Laufe der Zeit ändert. Der Untersuchungszeitraum reichte von Juni bis August 2011 und wurde in 3 Durchgänge unterteilt. Die Fließrinnen wurden wöchentlich mithilfe eines modifizierten Douglas‐Samplers beprobt. Des Weiteren wurde die Oberfläche des Biofilmes fotografiert, graphisch analysiert und die Bedeckung der ATSs im Freiland geschätzt. Die mikroskopische Auswertung und Pigmentanalysen erfolgten im Labor. Die Ergebnisse der Studie zeigen, dass das angebotene Substrat innerhalb kürzester Zeit kolonisiert wurde. Bereits eine Woche nach Exposition der ATSs konnten 20 – 30 verschieden Arten bestimmt werden. Weiters zeichnete sich die Algengemeinschaft durch hohe Diversität aus, denn während des gesamten Untersuchungszeitraumes wurden an die 200 verschiede Algentaxa registriert. Diese gehörten hauptsächlich zu den Chlorophyta, Bacillariophyceae und Cyanoprocaryota. Generell stieg die Zahl der vorkommenden Arten im Laufe der Versuchsperiode an und statistische Auswertungen der Kieselalgengemeinschaft zeigten, dass die Zusammensetzung der Arten hauptsächlich von saisonalen Faktoren und der Sukzession beeinflusst wird.In the present study, the algal community structure growing on artificial stream mesocosms was investigated. The so‐called algal turf scrubbers (ATSs were connected to a water purification system of a highly eutrophicated backwater in Vienna. The main objective of this study was to identify the succession rate and composition of the algal biomass. Sampling was done on a weekly basis with a modified Douglas sampler from June to August 2011 and comprised 3 runs. Estimation of the coverage and photographic documentation for micromapping was done in the field and microscopic analyses of both living and fixed material were carried out in the laboratory. Additionally, pigment analyses were performed to get insight into contribution of algal groups to total biomass. The microscopic analyses revealed a highly diverse community. About 200 taxa were identified mainly belonging to Chlorophyta (64 species), Bacillariophyceae (63 species) and Cyanoprocaryota (34 species). Already one week after exposition, 20 – 30 different taxa were detected on the ATSs, suggesting a rapid colonization of the offered substrate. Additionally the results obtained by nonmetric multidimensional scaling (final stress of 8.58) implicate that not only seasonal but also successional processes had an impact on the species composition on the ATSs. The first axis (r2 = 0.387) separated the algal community found at earlier stages from the dates towards the end of each run and the second axis (r2 = 0.459) split the first run clearly from the third run

Ecological and evolutionary role of seed banks for toxic dinoflagellate Alexandrium ostenfeldii

Phytoplankton plays a pivotal role for aquatic ecosystem functioning and global biogeochemistry. Climate change has affected phytoplankton community composition and distribution in the last decades, including a higher prevalence for harmful algal blooms in many areas. The globally distributed dinoflagellate Alexandrium ostenfeldii has for example started to form dense toxic blooms in the Baltic Sea and a new bloom location was recently discovered in western Japan. To survive unfavorable conditions this species forms resting stages, which may accumulate in sediments, forming a “seed bank”. The aim of this thesis was to investigate the relevance of the seed bank for the ecology and evolution of A. ostenfeldii and to understand the implications of these findings for persistence and possible expansion under ongoing global change. A combination of field surveys in Finland and Japan, experimental work and genotyping were carried out to address these aims. The results indicate that the seed bank stores a large clonal diversity, underlining its importance for stabilizing local populations against environmental fluctuations. No population structure was detected in temporal parts of a pelagic population, showing that differentiation does not happen during one season. The life cycle of A. ostenfeldii was found to be highly versatile, allowing overwintering of asexual resting stages without a pronounced dormancy period, and sexual reproduction throughout the season. Predicted future temperature and salinity did not affect germination of A. ostenfeldii, but affected growth rates, demonstrating their selective effect on the pelagic part of the population when detached from the seed bank. In addition, the importance of resting stages for colonizing new habitats, was stressed by the close relationship found between a recently discovered bloom population in Japan and geographically distant populations of similar habitats. Low genetic diversity indicated a recent introduction, potentially due to anthropogenic dispersal of resting stages. In conclusion, the seed bank plays a pivotal role for evolution and ecology of A. ostenfeldii. It ensures survival of a genetically diverse population, and slows down evolution, by linking contemporary populations to past populations via frequent re-seeding of resting stages. Although selection is buffered by phenotypic plasticity, future temperature and salinity may affect the pelagic part of the population, in the long run. A generalist life cycle of A. ostenfeldii and the presence of a seed bank support persistence and potential future temporal and spatial expansion under global change.Kasviplanktonilla on keskeinen merkitys vesiekosysteemien toiminnalle ja maailmanlaajuiselle biogeokemialle. Ilmastonmuutos on viime vuosikymmeninä vaikuttanut kasviplanktonyhteisöjen koostumukseen ja levinneisyyteen, ja johtanut muun muassa haitallisten leväkukintojen yleistymiseen monilla alueilla. Esimerkiksi maailmanlaajuisesti esiintyvä panssarisiimalevä Alexandrium ostenfeldii on alkanut muodostaa tiheitä, myrkyllisiä kukintoja Itämerellä ja uusi lajin kukinta-alue havaittiin äskettäin Länsi-Japanissa. Selviytyäkseen epäsuotuisista olosuhteista tämä laji muodostaa lepovaiheita, jotka voivat kertyä meren pohjasedimenttiin muodostaen ”siemenpankin”. Tämän väitöskirjatyön tavoitteena oli tutkia siemenpankin ekologista ja evolutiivista merkitystä A. ostenfeldiille, sekä sen vaikutusta lajin esiintymiseen ja mahdolliseen levittäytymiseen käynnissä olevan maailmanlaajuisen ympäristömuutoksen myötä. Työ koostui kenttätutkimuksista Suomessa ja Japanissa sekä kokeellisista tutkimuksista laboratorioympäristössä. Työssä tutkittiin myös lajin geneettistä monimuotoisuutta. Tulokset osoittavat, että siemenpankin monimuotoisuus on suurta, mikä korostaa siemenpankin merkitystä paikallisten populaatioiden vakauttajana vaihtelevissa ympäristöoloissa. Avoveden populaatiossa ei havaittu ajallista populaatiorakennetta, mikä osoittaa, että populaatio ei erilaistu yhden kasvukauden aikana. A. ostenfeldiin elinkierron havaittiin olevan hyvin monimuotoinen, sisältäen suvuttomasti muodostuneita lepovaiheita, jotka talvehtivat vajoamatta selvään lepotilaan, sekä koko kasvukauden ajan jatkuvaa suvullista lisääntymistä. Tulevaisuudessa mahdollisesti vallitsevia ympäristöolosuhteita vastaavat veden lämpötila- ja suolaisuusolosuhteet eivät vaikuttaneet A. ostenfeldiin leposolujen itämiseen, mutta ne vaikuttivat lajin kasvunopeuteen, mikä osoittaa, että nämä olosuhteet toimivat valintapaineena siemenpankista erillisessä avoveden populaatiossa. Lepovaiheilla on merkitystä myös lajin levittäytymiselle uusille elinalueille, sillä äskettäin Japanista löydetyn leväkukintapopulaation ja samanlaisissa elinympäristöissä elävien, maantieteellisesti kaukaisten populaatioiden havaittiin olevan läheistä sukua keskenään. Japanilaisen populaation pieni geneettinen monimuotoisuus viittaa siihen, että laji on saapunut alueelle äskettäin, mahdollisesti ihmisen levittämien lepovaiheiden avulla. Väitöskirjatyön johtopäätöksenä on, että siemenpankilla on keskeinen evolutiivinen ja ekologinen merkitys A. ostenfeldiille. Se takaa geneettisesti monimuotoisen populaation jatkuvuuden ja hidastaa evoluutiota liittämällä nykypopulaatiot edeltäviin populaatioihin lepovaiheiden jatkuvan uudelleen muodostumisen kautta. Vaikka lajin yksilöiden joustavuus ja sopeutuvuus tasapainottaa valintapainetta, lämpötilan ja suolaisuuden muutoksella voi pitkällä aikavälillä olla vaikutusta avovesipopulaatioon. A. ostenfeldiin generalistinen elinkiertomalli ja siemenpankki ylläpitävät lajin esiintymistä ja mahdollisesti edistävät sen ajallista ja paikallista levittäytymistä tulevaisuudessa maailmanlaajuisen ympäristömuutoksen myötä

Future temperature and salinity do not exert selection pressure on cyst germination of a toxic phytoplankton species

Abstract Environmental conditions regulate the germination of phytoplankton resting stages. While some factors lead to synchronous germination, others stimulate germination of only a small fraction of the resting stages. This suggests that habitat filters may act on the germination level and thus affect selection of blooming strains. Benthic ?seed banks? of the toxic dinoflagellate Alexandrium ostenfeldii from the Baltic Sea are genetically and phenotypically diverse, indicating a high potential for adaptation by selection on standing genetic variation. Here, we experimentally tested the role of climate-related salinity and temperature as selection filters during germination and subsequent establishment of A. ostenfeldii strains. A representative resting cyst population was isolated from sediment samples, and germination and reciprocal transplantation experiments were carried out, including four treatments: Average present day germination conditions and three potential future conditions: high temperature, low salinity, and high temperature in combination with low salinity. We found that the final germination success of A. ostenfeldii resting cysts was unaffected by temperature and salinity in the range tested. A high germination success of more than 80% in all treatments indicates that strains are not selected by temperature and salinity during germination, but selection becomes more important shortly after germination, in the vegetative stage of the life cycle. Moreover, strains were not adapted to germination conditions. Instead, highly plastic responses occurred after transplantation and significantly higher growth rates were observed at higher temperature. High variability of strain-specific responses has probably masked the overall effect of the treatments, highlighting the importance of testing the effect of environmental factors on many strains. It is likely that A. ostenfeldii populations can persist in the future, because suitable strains, which are able to germinate and grow well at potential future climate conditions, are part of the highly diverse cyst population. OPEN RESEARCH BADGES This article has been awarded Open Data badge. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.5061/dryad.c8c83nr. Learn more about the Open Practices badges from the Center for Open Science: https://osf.io/tvyxz/wiki.peerReviewe

A perspective on algal biogas

Algae are suggested as a biomass source with significant growth rates, which may be cultivated in the ocean (seaweed) or on marginal land (microalgae). Biogas is suggested as a beneficial route to sustainable energy; however the scientific literature on algal biogas is relatively sparse. This report comprises a review of the literature and provides a state of the art in algal biogas and is aimed at an audience of academics and energy policy makers. It was produced by IEA Bioenergy Task 37 which addresses the challenges related to the economic and environmental sustainability of biogas production and utilisation.JRC.F.8-Sustainable Transpor

Seasonal genotype dynamics of a marine dinoflagellate : Pelagic populations are homogeneous and as diverse as benthic seed banks

Genetic diversity is the basis for evolutionary adaptation and selection under changing environmental conditions. Phytoplankton populations are genotypically diverse, can become genetically differentiated within small spatiotemporal scales and many species form resting stages. Resting stage accumulations in sediments (seed banks) are expected to serve as reservoirs for genetic information, but so far their role in maintaining phytoplankton diversity and in evolution has remained unclear. In this study we used the toxic dinoflagellate Alexandrium ostenfeldii (Dinophyceae) as a model organism to investigate if (i) the benthic seed bank is more diverse than the pelagic population and (ii) the pelagic population is seasonally differentiated. Resting stages (benthic) and plankton (pelagic) samples were collected at a coastal bloom site in the Baltic Sea, followed by cell isolation and genotyping using microsatellite markers (MS) and restriction site associated DNA sequencing (RAD). High clonal diversity (98%-100%) combined with intermediate to low gene diversity (0.58-0.03, depending on the marker) was found. Surprisingly, the benthic and pelagic fractions of the population were equally diverse, and the pelagic fraction was temporally homogeneous, despite seasonal fluctuation of environmental selection pressures. The results of this study suggest that continuous benthic-pelagic coupling, combined with frequent sexual reproduction, as indicated by persistent linkage equilibrium, prevent the dominance of single clonal lineages in a dynamic environment. Both processes harmonize the pelagic with the benthic population and thus prevent seasonal population differentiation. At the same time, frequent sexual reproduction and benthic-pelagic coupling maintain high clonal diversity in both habitats.Peer reviewe

Guidelines for using environmental DNA in Finnish marine phytoplankton monitoring – Improved biodiversity assessment through method complementation

This document is a methodological guide for using a genomic ecosystem survey technique (eDNA metabarcoding) to supplement conventional phytoplankton monitoring of the Finnish marine monitoring program. The guidelines describe the detection of eukaryotic and prokaryotic phytoplankton with 18S and 16S rDNA gene primers, using high-throughput sequencing. The document includes information on sampling, sample processing, molecular biological work, quality control, and bioinformatics so that the method can be applied in addition to standardized light microscopy. The guidelines are based on a first pilot project testing the integration of eDNA metabarcoding in Finnish marine phytoplankton monitoring and will be developed further, according to evolving genetic methods and international guidelines and standards. Suggestions on steps towards introducing eDNA methodology in phytoplankton monitoring are included in the guidelines. Using eDNA metabarcoding to complement standardized light microscopy advances conventional monitoring and research of phytoplankton communities to assess biodiversity and the status of the marine environment. Menetelmäohje DNA-viivakoodaustekniikan käyttöön meren kasviplanktonseurannassa Tässä julkaisussa kuvataan menetelmäohje DNA-viivakoodeihin perustuvan eDNA (ympäristö-DNA) -metaviivakoodaustekniikan käytöstä Suomen merenhoidon seurantaohjelmaan kuuluvan kasviplanktonseurannan tukena. Aitotumaisen kasviplanktonin (mikrolevät) tunnistamiseen soveltuvan 18S rDNA -menetelmän lisäksi ohjeessa kuvataan esitumaisten syanobakteerien (sinilevät) analysointi 16S rDNA -menetelmällä käyttäen korkean käsittelytehon sekvensointia (high-throughput sequencing). Ohje sisältää yksityiskohtaiset tiedot eDNA -näytteiden keräämisestä, näytteiden käsittelystä, molekyylibiologisista työvaiheista, bioinformatiikka-analyyseistä ja laadunvarmennuksesta. Ohje perustuu ympäristöministeriön rahoittaman hankkeen tuloksiin. Ohjeistusta tullaan kehittämään jatkossa sitä mukaa, kun uusia tutkimustuloksia, kansainvälisiä ohjeita ja standardeja julkaistaan. Ohjeistus sisältää ehdotuksen etenemisvaiheista, jotka kannattaa huomioida, kun eDNA-menetelmää ryhdytään ottamaan mukaan kasviplanktonseurantaan. eDNA-menetelmää voidaan käyttää valomikroskopointimenetelmän ohella tarkentamaan ja tehostamaan kasviplanktonyhteisöjen biodiversiteetin seurantaa ja tutkimusta meriympäristön tilan arvioita varten

Intraspecific trait variation and trade-offs within and across populations of a toxic dinoflagellate

Abstract Intraspecific trait diversity can promote the success of a species, as complementarity of functional traits within populations may enhance its competitive success and facilitates resilience to changing environmental conditions. Here, we experimentally determined the variation and relationships between traits in 15 strains of the toxic dinoflagellate Alexandrium ostenfeldii derived from two populations. Measured traits included growth rate, cell size, elemental composition, nitrogen uptake kinetics, toxin production and allelochemical potency. Our results demonstrate substantial variation in all analysed traits both within and across populations, particularly in nitrogen affinity, which was even comparable to interspecific variation across phytoplankton species. We found distinct trade-offs between maximum nitrogen uptake rate and affinity, and between defensive and competitive traits. Furthermore, we identified differences in trait variation between the genetically similar populations. The observed high trait variation may facilitate development and resilience of harmful algal blooms under dynamic environmental conditions

Biofilm scrubbing for restoration—algae community composition and succession in artificial streams

Photoautotrophic biofilms play a pivotal role in self-purification of rivers. We took advantage of the biofilm’s cleaning capacity by applying artificial stream mesocosms, called algae turf scrubberTM (ATS), to reduce the nutrient load of a highly eutrophicated backwater in Vienna (Austria). Since purification strongly depends on benthic algae on the ATS, we focused on the algae community composition and succession. Estimation of coverage, photographic documentation for micromapping, species identification and pigment analyses were carried out. Already one week after exposition, 20–30 different taxa were recorded, suggesting a rapid colonization of the substrate. In total around 200 taxa were identified, mainly belonging to Chlorophyta, Bacillariophyceae and Cyanoprokaryota. Nonmetric multidimensional scaling implied that season and succession strongly influenced species composition on the ATS and a minimum turnover of 0.28 indicates a development towards a more stable community at the end of experiments. We measured maximum biomass production of ~250 g m−2 in June and August and during a period of 5 months nearly 19 kg ha−1 phosphorus could be removed. ATS systems proved to retain nutrients and produce algae biomass in an environmentally friendly and cost effective way and thus support restoration of highly eutrophicated water bodies

Data from: Future temperature and salinity do not exert selection pressure on cyst germination of a toxic phytoplankton species

Environmental conditions regulate the germination of phytoplankton resting stages. While some factors lead to synchronous germination, others stimulate germination of only a small fraction of the resting stages. This suggests that habitat filters may act on the germination level and thus affect selection of blooming strains. Benthic “seed banks” of the toxic dinoflagellate Alexandria ostenfeldii from the Baltic Sea are genetically and phenotypically diverse, indicating a high potential for adaptation by selection on standing genetic variation. Here, we experimentally tested the role of climate‐related salinity and temperature as selection filters during germination and subsequent establishment of A. ostenfeldii strains. A representative resting cyst population was isolated from sediment samples, and germination and reciprocal transplantation experiments were carried out, including four treatments: Average present day germination conditions and three potential future conditions: high temperature, low salinity, and high temperature in combination with low salinity. We found that the final germination success of A. ostenfeldii resting cysts was unaffected by temperature and salinity in the range tested. A high germination success of more than 80% in all treatments indicates that strains are not selected by temperature and salinity during germination, but selection becomes more important shortly after germination, in the vegetative stage of the life cycle. Moreover, strains were not adapted to germination conditions. Instead, highly plastic responses occurred after transplantation and significantly higher growth rates were observed at higher temperature. High variability of strain‐specific responses has probably masked the overall effect of the treatments, highlighting the importance of testing the effect of environmental factors on many strains. It is likely that A. ostenfeldii populations can persist in the future, because suitable strains, which are able to germinate and grow well at potential future climate conditions, are part of the highly diverse cyst population

Data

Zipped files and a README file, containing variable descriptions and explanations