20 research outputs found
Fungal assemblages in predictive stream bioassessment: A cross-taxon comparison along multiple stressor gradients
Highlights
âą We compared fungi, invertebrates and diatoms in model-based stream bioassessment.
âą Fungal models virtually equaled the overall best model in precision and accuracy.
âą Fungi were superior in identifying streams degraded by multiple stressors.
âą Results strongly support the use of microbial communities in stream bioassessment.Degradation of freshwater ecosystems requires efficient tools for assessing the ecological status of freshwater biota and identifying potential cause(s) for their biological degradation. While diatoms and macroinvertebrates are widely used in stream bioassessment, the potential utility of microbial communities has not been fully harnessed. Using data from 113 Finnish streams, we assessed the performance of aquatic leaf-associated fungal decomposers, relative to benthic macroinvertebrates and diatoms, in modelling-based bioassessment. We built multi-taxon niche -type predictive models for fungal assemblages by using genus-based and sequence-based identification levels. We then compared the modelsâ precision and accuracy in the prediction of reference conditions (number of native taxa) to corresponding models for macroinvertebrates and diatoms. Genus-based fungal model nearly equalled the accuracy and precision of our best model (macroinvertebrates), whereas the sequence-based model was less accurate and tended to overestimate the number of taxa. However, when the models were applied to streams disturbed by anthropogenic stressors (nutrient enrichment, sedimentation and acidification), alone or in combination, the sequence-based fungal assemblages were more sensitive than other taxonomic groups, especially when multiple stressors were present. Microbial leaf decomposition rates were elevated in sediment-stressed streams whereas decomposition attributable to leaf-shredding macroinvertebrates was accelerated by nutrients and decelerated by sedimentation. Comparison of leaf decomposition results to model output suggested that leaf decomposition rates do not detect effectively the presence of multiple simultaneous disturbances. The rapid development of global microbial database may soon enable species-level identification of leaf-associated fungi, facilitating a more precise and accurate modelling of reference conditions in streams using fungal communities. This development, combined with the sensitivity of aquatic fungi in detecting the presence of multiple human disturbances, makes leaf-associated fungal assemblages an indispensable addition in a stream ecologistâs toolbox
Fungal assemblages in predictive stream bioassessment : A cross-taxon comparison along multiple stressor gradients
Highlights
âą We compared fungi, invertebrates and diatoms in model-based stream bioassessment.
âą Fungal models virtually equaled the overall best model in precision and accuracy.
âą Fungi were superior in identifying streams degraded by multiple stressors.
âą Results strongly support the use of microbial communities in stream bioassessment.Degradation of freshwater ecosystems requires efficient tools for assessing the ecological status of freshwater biota and identifying potential cause(s) for their biological degradation. While diatoms and macroinvertebrates are widely used in stream bioassessment, the potential utility of microbial communities has not been fully harnessed. Using data from 113 Finnish streams, we assessed the performance of aquatic leaf-associated fungal decomposers, relative to benthic macroinvertebrates and diatoms, in modelling-based bioassessment. We built multi-taxon niche -type predictive models for fungal assemblages by using genus-based and sequence-based identification levels. We then compared the modelsâ precision and accuracy in the prediction of reference conditions (number of native taxa) to corresponding models for macroinvertebrates and diatoms. Genus-based fungal model nearly equalled the accuracy and precision of our best model (macroinvertebrates), whereas the sequence-based model was less accurate and tended to overestimate the number of taxa. However, when the models were applied to streams disturbed by anthropogenic stressors (nutrient enrichment, sedimentation and acidification), alone or in combination, the sequence-based fungal assemblages were more sensitive than other taxonomic groups, especially when multiple stressors were present. Microbial leaf decomposition rates were elevated in sediment-stressed streams whereas decomposition attributable to leaf-shredding macroinvertebrates was accelerated by nutrients and decelerated by sedimentation. Comparison of leaf decomposition results to model output suggested that leaf decomposition rates do not detect effectively the presence of multiple simultaneous disturbances. The rapid development of global microbial database may soon enable species-level identification of leaf-associated fungi, facilitating a more precise and accurate modelling of reference conditions in streams using fungal communities. This development, combined with the sensitivity of aquatic fungi in detecting the presence of multiple human disturbances, makes leaf-associated fungal assemblages an indispensable addition in a stream ecologistâs toolbox
Habitat patchiness, ecological connectivity and the uneven recovery of boreal stream ecosystems from an experimental drought
Ongoing climate change is increasing the occurrence and intensity of drought episodes worldwide, including in boreal regions not previously regarded as drought prone, and where the impacts of drought remain poorly understood. Ecological connectivity is one factor that might influence community structure and ecosystem functioning post-drought, by facilitating the recovery of sensitive species via dispersal at both local (e.g. a nearby habitat patch) and regional (from other systems within the same region) scales. In an outdoor mesocosm experiment, we investigated how impacts of drought on boreal stream ecosystems are altered by the spatial arrangement of local habitat patches within stream channels, and variation in ecological connectivity with a regional species pool. We measured basal ecosystem processes underlying carbon and nutrient cycling: (a) algal biomass accrual; (b) microbial respiration; and (c) decomposition of organic matter, and sampled communities of aquatic fungi and benthic invertebrates. An 8-day drought event had strong impacts on both community structure and ecosystem functioning, including algal accrual, leaf decomposition and microbial respiration, with many of these impacts persisting even after water levels had been restored for 3.5 weeks. Enhanced connectivity with the regional species pool and increased aggregation of habitat patches also affected multiple response variables, especially those associated with microbes, and in some cases reduced the effects of drought to a small extent. This indicates that spatial processes might play a role in the resilience of communities and ecosystem functioning, given enough time. These effects were however insufficient to facilitate significant recovery in algal growth before seasonal dieback began in autumn. The limited resilience of ecosystem functioning in our experiment suggests that even short-term droughts can have extended consequences for stream ecosystems in the world's vast boreal region, and especially on the ecosystem processes and services mediated by algal biofilms
Latitude dictates plant diversity effects on instream decomposition
Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113 degrees of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes
Dietary differences between Baltic ringed seals (Phoca hispida botnica) based on stable isotope and fatty acid analyses
ItĂ€merennorppa (Phoca hispida botnica) on uhanalainen ja suojeltu laji ItĂ€merellĂ€, sillĂ€ hyljekannat romahtivat 1900-luvulla laajan metsĂ€styksen ja ympĂ€ristömyrkkyjen vuoksi. PerĂ€merellĂ€ hyljekanta on tĂ€llĂ€ hetkellĂ€ kasvussa, ja harmaahylkeiden (Halichoerus grypus) ja itĂ€merennorppien aiheuttamat vahingot ovat kasvaneet. Hylkeiden vuoksi kalastajat ovat menettĂ€neet saalista. Hylkeet ovat myös vahingoittaneet kaloja ja rikkoneet pyydyksiĂ€. Eniten tuhoa hylkeet ovat aiheuttaneet siika- (Coregonus lavaretus (L.), kuha- (Sander lucioperca (L.) ja lohi- (Salmo salar L.) kalastukselle. Tutkimuksen tavoitteena oli tutkia 45 itĂ€merennorpan ravintoa kahden biokemiallisen menetelmĂ€n avulla: vakaat isotoopit ja rasvahappomÀÀritys. Hiilen ja typen vakaita isotooppeja (ÎŽ13C ja ÎŽ15N) tutkittiin lihas- ja maksakudoksesta ja rasvahappokoostumus mÀÀritettiin traanista. Ravintoa tutkittiin maksakudoksesta, joka mÀÀrittÀÀ ravinnon muutaman viimeisten viikkojen ajalta ennen pyydystystĂ€, ja tulosta verrattiin ravintomÀÀrityksiin mahanĂ€ytteistĂ€. Lihaskudoksen isotooppiarvoista ja traanin rasvahappokoostumuksesta arvioitiin norppien ravintoa viimeisten kuukausien ajalta ennen pyydystystĂ€. Hylkeiden ravinto koostui pÀÀasiassa pelagisista kalalajeista ja pohjakaloista. KevÀÀllĂ€ nuoret ja aikuiset hylkeet söivĂ€t samankaltaista ravintoa, mutta syksyllĂ€ aikuiset söivĂ€t enemmĂ€n petokalaryhmĂ€n kalalajeja (36 %) verrattaessa nuoriin yksilöihin (34 %). Biokemialliset menetelmĂ€t mÀÀrittivĂ€t hylkeiden ravinnon koostuvan silakasta (Clupea harengus membras (L.) ja kolmipiikistĂ€ (Gasterosteus aculeatus L.). Pohjakalat kuten kivinilkka (Zoarces viviparous) ja hĂ€rkĂ€simppu (Myoxocephalus quadricornis) olivat myös hylkeiden ravintoa. ĂyriĂ€isiĂ€ hylkeet eivĂ€t kĂ€yttĂ€neet ravinnokseen. Hylkeiden ravinnon kĂ€yttö PerĂ€merellĂ€ ei ole yksiselitteinen. Uhanalaisen hyljelajin ravinnonkĂ€yttöÀ tulisi tutkia enemmĂ€n, jotta ongelmat kalatalouden kanssa voitaisiin ratkaista.The Baltic ringed seal (Phoca hispida botnica) is an endangered and protected species in the Baltic Sea which underwent a significant decline in the 20th century mainly due to extensive hunting and environmental toxins. The species is currently increasing its numbers in the Bothnian Bay, where damage caused to fisheries by grey seals (Halichoerus grypus) and Baltic ringed seals has also increased. Seals not only reduce the catch, but also damage fish and break fish traps. Damage has been highest for whitefish (Coregonus lavaretus (L.), zander (Sander lucioperca (L.), and salmon (Salmo salar L.) fisheries. The aim of this thesis was to study the feeding and foraging behaviour of 45 individual Baltic ringed seals to determine species-specific diet using two biochemical methods in combination: stable isotope analysis and fatty acid analysis. Carbon and nitrogen isotopes (ÎŽ13C and ÎŽ15N) were analysed from muscle and liver tissues, while fatty acid composition was determined from blubber tissues. Short-term diet (within weeks) was determined from isotopic values of liver tissue, and was compared with analyses of stomach contents. Long-term diet (within months) was analysed from isotope values of muscle tissue and fatty acid composition of blubber tissues. The ringed seal diet was concentrated on pelagic and benthic fish species on the Swedish side of the Bothnian Bay. In spring adult and juvenile seals had similar diets, but in autumn adult seals concentrated slightly more on predator fish (36 %) than juveniles (34 %). According to biochemical methods, the most common prey items for seals were Baltic herring (Clupea harengus membras (L.) and three-spined stickleback (Gasterosteus aculeatus L.). There were differences between individuals. Benthic fish species such as eelpout (Zoarces viviparous) and fourhorn sculpin (Myoxocephalus quadricornis) were also abundant in seal diets. There was no evidence of isopods being used as prey. The dietary and foraging behaviour of ringed seals is perhaps not as straightforward as previously assumed. Therefore, further research on diets of this endangered species is needed to help solve problems with fisheries while maintaining sustainable management of seals
Anthropogenic impacts and restoration of boreal spring ecosystems
Abstract
Human activities have increasingly altered freshwater ecosystems. Land use is a major driver of habitat loss and land use-related input of nutrients and other pollutants from agriculture, forestry and urbanization have deteriorated water quality. Freshwater research has mainly focused on lakes and streams while the effects of anthropogenic stressors on groundwater-dependent ecosystems (GDEs) are poorly known. Likewise, the effectiveness of ecological restoration in mitigating human disturbance in GDEs remains understudied. In this thesis, I studied the effects of two main anthropogenic stressors â land drainage and groundwater contamination â on boreal spring ecosystems and evaluated the recovery of spring biodiversity and ecosystem functioning after habitat restoration. I applied several structural (macroinvertebrates, bryophytes, leaf-decomposing fungi and groundwater bacteria) and functional (organic matter decomposition and primary productivity) measures to provide a comprehensive insight into these issues.
Both stressors modified spring ecosystems. Land drainage reduced the key ecosystem processes. Long-term monitoring of drainage-impacted springs showed a marked biodiversity loss and change of spring-dwelling bryophytes, and no signs of recovery were observed after about 20 years since the intial land drainage. Groundwater contamination, indicated by elevated nitrate and chloride concentrations, altered the structure of spring biota, reduced their taxonomic diversity and suppressed primary productivity in the most severely contaminated springs. Spring restoration improved habitat quality by reducing drainage-induced inflow of surface water, thus re-establishing groundwater-dominated hydrological conditions. Restoration increased abundance of habitat-specialist bryophytes and shifted macroinvertebrate composition towards natural conditions, despite the restoration actions being fairly recent. Anthropogenic activities can thus cause severe structural and functional degradation of spring ecosystems, and their self-recovery potential from these stressors seems low. Habitat restoration bears great promise as a cost-effective approach to mitigate drainage-induced impacts on spring ecosystems, but protection and co-management of groundwater resources are urgently needed to secure the role of springs as biodiversity hotspots in the boreal forest landscape.TiivistelmÀ
Ihmistoiminta muuttaa yhĂ€ enemmĂ€n vesiekosysteemejĂ€. MaankĂ€yttö on johtanut elinympĂ€ristöjen hĂ€viĂ€miseen, ja siihen liittyvĂ€ ravinne- ja haitta-ainekuormitus maa- ja metsĂ€taloudesta sekĂ€ kaupunkiympĂ€ristöistĂ€ on merkittĂ€vĂ€sti huonontanut veden laatua johtaen maailmanlaajuiseen vesiluonnon monimuotoisuuden heikentymiseen. Vesiekosysteemien tutkimus on keskittynyt pÀÀasiassa jĂ€rvi- ja jokiympĂ€ristöihin, kun ihmistoiminnan vaikutukset pohjavesiriippuvaisiin ekosysteemeihin tunnetaan edelleen huonosti. Samoin kunnostusten merkitys pohjavesiriippuvaisten ekosysteemien tilan parantamiseksi on selvittĂ€mĂ€ttĂ€. VĂ€itöskirjassani tarkastelin kahden keskeisen ihmistoiminnan â metsĂ€ojituksen ja pohjaveden laadun heikkenemisen â vaikutuksia lĂ€hde-ekosysteemeihin sekĂ€ arvioin elinympĂ€ristökunnostusten vaikutuksia niiden rakenteeseen ja toimintaan. Sovelsin työssĂ€ni rakenteellisia (pohjaelĂ€imet, sammalet, lehtikariketta hajottavat sienet ja pohjavesibakteerit) ja toiminnallisia (eloperĂ€isen aineksen hajoaminen ja perustuotanto) mittareita tuottamaan kattavan kĂ€sityksen tutkimuskysymyksiini.
SekÀ metsÀojitukset ettÀ pohjaveden laadun heikkeneminen aiheuttavat muutoksia lÀhteiden rakenteessa ja toiminnassa. MetsÀojitukset hidastavat keskeisiÀ ekosysteemitoimintoja ja johtavat lÀhdesammallajiston muutokseen ja monimuotoisuuden taantumiseen. Pohjaveden pilaantuminen, jota työssÀ ilmennettiin kohonneilla nitraatti- ja kloridipitoisuuksilla, heikentÀÀ lÀhdelajiston monimuotoisuutta, muuttaa lajikoostumusta ja johtaa perustuotannon laskuun voimakkaimmin kuormitetuissa lÀhteissÀ. Kunnostus parantaa lÀhde-elinympÀristön laatua vÀhentÀmÀllÀ metsÀojien aiheuttamaa pintavesivaikutusta palauttaen pohjavesivaltaisen hydrologisen tilan. LÀhdekunnostusten myötÀ lÀhdesammaleet runsastuvat ja pohjaelÀinyhteisön rakenne palautuu luonnontilaisten lÀhteiden kaltaiseksi, vaikka kunnostuksista on kulunut vasta muutamia vuosia. VÀitöskirjan tulokset osoittavat, ettÀ ihmisen toiminta voi aiheuttaa muutoksia lÀhde-ekosysteemien rakenteessa ja toiminnassa ja lÀhteiden luontainen palautuminen hÀiriöstÀ on hidasta. LÀhde-elinympÀristöjen kunnostus vaikuttaa lupaavalta suojelutoimenpiteeltÀ metsÀojitusten vaikutusten vÀhentÀmisessÀ, mutta lÀhteiden sÀilyttÀminen monimuotoisena ja suojelullisesti arvokkaana luontotyyppinÀ edellyttÀÀ pohjavesivarojen hallinnan ja tilan suojelun tehostamista
Nitrogen removal of mine-influenced water in a hybrid bioreactor with floating hook-moss (Warnstorfia fluitans) in cold climate conditions
To remove nitrogen in cold conditions, we studied new nature-based treatment solutions using six pilot-scale reactors. The pilots were woodchip bioreactor (WBR), aquatic floating hook-moss (Warnstorfia fluitans) (MBR), and a combined woodchip and floating hook-moss hybrid unit (HBR) with an improved hydraulic design. The experiment was run in a climate room at temperatures of 10 °C and 5 °C and using mine water from two sites located in northern Finland. Unlike traditional horizontal flow woodchip bioreactors, in this study the hydraulic efficiency was improved from poor (λ = 0.06) in the woodchip bioreactor to satisfactory (λ = 0.51) in the hybrid unit by inserting two inner plates along the water flow and adding floating hook-moss. The hybrid bioreactor revealed the highest capability of nitrogen removal in all inorganic forms at T †10 °C with a mean HRT of 70.5 h. On average, 30â78 % of dissolved inorganic nitrogen was removed in the hybrid unit, which was 2 and 3 times more than in units consisting only of woodchip or floating hook-moss. The hybrid bioreactor revealed a maximum NOâ3-N removal rate of 1.0â5.2 g mâ3 dâ1 and a 21.8â99.7 % removal efficiency for an average incoming NOâ3-N load of 40 g dâ1. The maximum NH+4-N removal efficiency of 75.6 and 53 % took place in HBR and MBR, respectively, when the incoming NH+4-N load was 23.6 ± 0.7 g dâ1 at 10 °C. Over the 154 days of the experiment, the hybrid unit removed a total of 2.95 kg DIN-N, which was 0.8 kg higher than the sum of the DIN-N mass removed in the individual woodchip (1.7 kg) and moss units (0.55 kg). The nitrogen content of the aquatic moss was higher in the hybrid unit compared to the moss unit, showing a higher contribution of N plant uptake. Overall, our results suggest that combining woodchips and aquatic moss in a hybrid unit with improved hydraulic efficiency using inner walls may enhance nitrogen removal in cold climate conditions
Nitrogen removal of mine-influenced water in a hybrid bioreactor with floating hook-moss (Warnstorfia fluitans) in cold climate conditions
To remove nitrogen in cold conditions, we studied new nature-based treatment solutions using six pilot-scale reactors. The pilots were woodchip bioreactor (WBR), aquatic floating hook-moss (Warnstorfia fluitans) (MBR), and a combined woodchip and floating hook-moss hybrid unit (HBR) with an improved hydraulic design. The experiment was run in a climate room at temperatures of 10 °C and 5 °C and using mine water from two sites located in northern Finland. Unlike traditional horizontal flow woodchip bioreactors, in this study the hydraulic efficiency was improved from poor (λ = 0.06) in the woodchip bioreactor to satisfactory (λ = 0.51) in the hybrid unit by inserting two inner plates along the water flow and adding floating hook-moss. The hybrid bioreactor revealed the highest capability of nitrogen removal in all inorganic forms at T †10 °C with a mean HRT of 70.5 h. On average, 30â78 % of dissolved inorganic nitrogen was removed in the hybrid unit, which was 2 and 3 times more than in units consisting only of woodchip or floating hook-moss. The hybrid bioreactor revealed a maximum NOâ3-N removal rate of 1.0â5.2 g mâ3 dâ1 and a 21.8â99.7 % removal efficiency for an average incoming NOâ3-N load of 40 g dâ1. The maximum NH+4-N removal efficiency of 75.6 and 53 % took place in HBR and MBR, respectively, when the incoming NH+4-N load was 23.6 ± 0.7 g dâ1 at 10 °C. Over the 154 days of the experiment, the hybrid unit removed a total of 2.95 kg DIN-N, which was 0.8 kg higher than the sum of the DIN-N mass removed in the individual woodchip (1.7 kg) and moss units (0.55 kg). The nitrogen content of the aquatic moss was higher in the hybrid unit compared to the moss unit, showing a higher contribution of N plant uptake. Overall, our results suggest that combining woodchips and aquatic moss in a hybrid unit with improved hydraulic efficiency using inner walls may enhance nitrogen removal in cold climate conditions
Growth of floating hook-moss (Warnstorfia fluitans) differs with nutrient and water flow adjustments in greenhouse and cold room conditions
Floating hook-moss (Warnstorfia fluitans) is a bryophyte growing in northern aquatic and peatland ecosystems. W. fluitans uptakes metals and excessive amounts of nitrogen from wastewater, which suggests that it may have commercial potential for use in phytoremediation. Optimization of growth conditions would allow artificial cultivation of floating hook moss in large quantities for phytoremediation applications. We tested how application of combined nutrient (NPK 7-2-2 ranging from 0.1 to 1 ml per liter of water) and water flow (ranging from 0.15 to 1.9 ml/min) treatments affect growth of W. fluitans in greenhouse conditions. At the end of the experiment, all treatment combinations were subjected to an additional cold room condition at low temperature (0â2 °C) without constant water flow. The moss generally produced biomass in the various treatment combinations. However, contrary to our expectations, we found that increase of nutrients and water flow had a negative effect on the growth of W. fluitans. The highest growth rates in the experiment were detected in the control unit that had no nutrient addition or applied water flow. Our results suggest that cold temperatures are beneficial for W. fluitans growth. Our results show that the commercial production of W. fluitans may not require nutrient or water flow manipulation, at least in the tested scale. Instead, the growth conditions should mimic the natural cold climate conditions of W. fluitans habitats in northern peatlands and/or spring ecosystems
Weather in two climatic regions shapes the diversity and drives the structure of fungal endophytic community of bilberry (Vaccinium myrtillus L.) fruit
Abstract Background Bilberry (Vaccinium myrtillus L.) is one of the most important economic and natural resources in Northern Europe. Despite its importance, the endophytic fungal community of the fruits has rarely been investigated. Biogeographic patterns and determinants of the fungal diversity in the bilberry fruit are poorly understood, albeit fungal endophytes can have a close relationship with the host plants. Here, we investigated the effect of climatic regions, and their weather conditions within growth season and soil properties on fungal endophytic communities of bilberry fruits collected from northern and southern regions of Finland using high-throughput sequencing technology targeting the internal transcribed spacer 2 ribosomal DNA region for fungi. Results Species richness and beta diversity (variation in community structure) were higher in the southern compared to the studied northern region. The weather condition of the growth season drove both fungal richness and community structure. Furthermore, abundance of the genera Venturia, Cladosporium, and Podosphaera was influenced by the weather, being different between the south and north regions. Conclusions We conclude that diversity and assembly structure of the fungal endophytes in bilberry fruits follow similar patterns as for foliar fungal endophytes, being shaped by various environmental factors, such as the climate and surrounding vegetation