Long-term warming experiments in arctic tundra have resulted in reduced moss cover and increased vascular plant cover. As mosses have a major impact on microclimatic conditions, changes in community composition can potentially alter direct and indirect drivers of productivity and decomposition, which are low in arctic ecosystems. This can potentially change the carbon balance. Therefore, it is of importance to investigate how the effects of warming on ecosystem processes depend on the identity of the moss species dominating the vegetation. Furthermore, because subarctic climate is expected to get warmer and wetter, it is essential to examine how warming effects depend on variation in precipitation as well. Thus, Gross Primary Production (GPP) and Ecosystem Respiration (Reco) fluxes, moss growth, and decomposition rate, were measured in plot pairs along a natural precipitation gradient in subarctic tundra Sweden. Each pair was dominated by one of three common moss species (Hylocomium splendens, Pleurozium schreberi and Sphagnum spp.), and were subjected to moss removal and Open Top Chamber (OTC) warming treatment combinations. Moss growth measurements were taken as a measure of productivity and Tea Bag Index was used as a measure of decomposition rate. Warming effects on GPP depended on both species and precipitation; Hylocomium and Sphagnum had highest productivity in warmed high-precipitation plots, whereas the effect was negative in all cases for Pleurozium. No significant interactions were found for the other response variables, but there was a positive effect of warming on Reco across all treatments, as well as a negative effect on decomposition. Warming induced increases in GPP and respiration, and decrease in decomposition rate, could imply that the increase in CO2 emissions from arctic ecosystems will be smaller than predicted, as the sequestration of CO2 in that case would exceed what is being emitted. Still, it is a complex matter and therefore crucial to further investigate the role of moss species in relation to warming effects on ecosystem processes.

When precipitation increases as a result of climate change during certain periods, demands are placed on how cities can cope with the increased handling of stormwater, rainwater and meltwater runoff. Umeå is a city with the vision of reaching 200,000 inhabitants by the year 2050 and that growth must be managed with ecological, economic, social and cultural sustainability. In a growing city, it is therefore important to include stormwater management as a central part of planning. This study aims to describe and analyze how the municipality of Umeå works towards a sustainable stormwater management. This will be done with the methods of document analysis and field studies.

The forest plays a large role both nationally and internationally towards a sustainable planet. Therefore, understanding non-industrial private forest owners’ preferences is important to achieve the environmental targets, since they are a large ownership group in Sweden. The present study focusses on non-industrial private forest owners’ harvesting decisions in Norrbotten. Furthermore, the study extends to analyze how the forest owners’ preferences towards promotion of ecosystem services are affected if compensation is offered. To understand the harvesting decisions of non-industrial private forest owners’, an empirical approach was used where a questionnaire was constructed. The data were analyzed through logistic regression. The results suggest that non-industrial private forest owners’ harvesting decision is positively affected by previous experience in the forest, days present in the forest, membership in a forest cooperative and a price increase of timber. Forest owners with economic objectives harvest more than owners with no or other objectives. No significant relationship between nature- and economic objectives in the harvesting decisions were identified. The results related to willingness to promote ecosystem services for compensation indicated ambiguous results.

Mangrove forests are highly productive ecosystems widespread in tropical and subtropical coastlines, with a coverage of 75% of the world’s tropical shorelines. Mangrove plants developed specific physiological and morphological adaptation to thrive in such unique environments. Together with plant adaptations, mangroves develop a tight partnership with microorganisms, mainly bacteria and fungi, that form the so-called mangrove-microbiome. Plant-associated microorganisms are generally recruited by the root system (root tissues and rhizosphere) and the colonization process starts with the release of root-related exudates detected by the surrounding edaphic microorganisms that are attracted in the rhizosphere zone. Then, root surface selects those microorganisms that can enter the tissues as endophytes. The microorganisms recruited belowground can migrate through the plant tissues by using the plant vessels and may colonize the aboveground compartments of the plant. Here, I aimed to evaluate the environmental origin and compartmentalization of the mangrove microbiome. To do this, I sampled bulk sediments, sea water, and mangrove plant compartments (root rhizosphere and endosphere, pneumatophores, shoot, leaves, flowers and propagules) of 20 gray mangrove trees (Avicennia marina L.) across two sites on the Red Sea coast of the King Abdullah University of Science and Technology (KAUST), Saudi Arabia. By high-throughput sequencing of the bacterial 16S rRNA gene, I showed that the bacterial assembly in A. marina plant compartments follows a clear niche partition process in which bacterial communities are actively recruited from the surrounding ecosystem (sediment and sea water) by the root system, and further distributed across the different plant organ and compartments. Moreover, the composition of microbiome detected had many similitudes with others previously described around the world, suggesting that certain bacteria represent a mangrove “core microbiome”. The conservation of microbiome composition, mainly driven by environmental and host selection, that beneficial bacteria provide to the plant and contribute to its growth and fitness by several mechanisms. Thus, the characterization and identification of mangrove microbiome can meliorate our knowledge regarding plant–microbe interactions, as well as put the bases for the development of Nature-based Solution (NBS) to enhance reforestation and rehabilitation of mangrove ecosystems

Thesis (M.Sc. (Zoology)) -- University of Limpopo, 2020 / Water pollution has been one of the major concerns all over the world for at least the past two decades. In South Africa, the Olifants River System is one of the most polluted river systems. Anthropogenic activities being carried out within the Olifants River Catchment area pose threats to the aquatic ecosystem. The Upper and Middle catchments are being characterised by intensive mining, industries, agricultural practices and inadequate sewage treatments. Thus, the aim of this study was to investigate the influence of mining activities on the water quality and health status of the Steelpoort River, a tributary of the Olifants River System. This was achieved through assessing the quality of water by analysing physico-chemical parameters, macro nutrients and metals at four selected sites, determining the response of macro invertebrate assemblages to water quality using the South African Scoring System (SASS) version 5 and determining the diversity of fish using the Fish Response Assessment Index (FRAI). Sampling of water, sediment, macro-invertebrates and fish was done seasonally (August 2017 – May 2018) at four selected sites. Site 1 and site 2 were located upstream while site 3 and site 4 were located midstream and downstream respectively. Water and sediment samples were analysed by WATERLAB (PTY) LTD by means of Inductively Coupled Plasma Optical Spectrometry (ICP-OES). Macro-invertebrates were sampled following the SASS protocol. Macro-invertebrates were identified, counted and recorded then released back to the river. Fish were sampled following the FRAI index protocol. The results obtained indicated that the system variables; pH, water temperature, dissolved oxygen and total dissolved solids fell within the target water quality range (TWQR) for aquatic ecosystems. However, some concentrations of macro-nutrients recorded were above the TWQR. These include ammonium at site 3 and nitrogen at sites 2, 3 and 4 which indicated that there was a variation in the influx of macro-nutrients into the river at different river sections. The higher concentrations of ammonium and nitrogen may adversely affect the functioning and survival of biological communities. The metal results indicated that most metals (As, B, Ba, Cd, Cu, Pb, Ni and Cr) fell within the recommended water and sediment quality guidelines (DWAF 1996c; CCME 2012). Chromium concentrations recorded in sediment were above the sediment quality guideline at all the selected sites (CCME 2012). Iron and Zn were also above the guideline values at all selected sites. In terms of physico-chemical parameters and metal concentrations indicated that the water quality of the Steelpoort River was fairly good. The macro-invertebrates were also analysed; their abundance, distribution and family richness indicated that there was a deterioration of water quality from upstream to downstream which may be an indication of increase in influx of pollutants and modifications in the stream such as flow, cover and microhabitat. The highest macro invertebrate abundance and richness was at site 1 while the lowest was at sites 3 and 4. Site 3 was highly modified while site 1 was the least modified site. The Ephemeroptera, Plecoptera and Trichoptera index (EPT) and Ephemeroptera, Plecoptera and Trichoptera/Chironomidae ratio (EPT/C ratio) analysis also confirmed that the water quality of the Steelpoort River is deteriorating from upstream to downstream. Site 1 had the highest value of EPT while site 2 had the highest value of EPT/C. Site 3 had the lowest value for both EPT and EPT/C ratio. The higher EPT and EPT/C ratio indicate the presence of highly sensitive taxa. The Canonical Correspondence Analysis (CCA) indicated a strong correlation between metals (Pb, Cr, Mg, As and Se) and macro-invertebrates (Pleidae, Ecnomidae, Athericidae, Synlestidae, Lestidae and Pyralidae). The SASS 5 results also indicated deterioration of water quality from upstream to downstream with the highest values of SASS score and Average Score Per Taxon (ASPT) being recorded at site 1 followed by site 2 while the lowest SASS score and ASPT were at site 3 followed by site 4. The use of fish as biological indicator also supported the same pattern of water quality deterioration and influx of pollutants which was previously indicated as increasing from upstream to downstream of the Steelpoort River. Site 1 had the highest fish abundance, while site 4 had the lowest fish abundance. However, the fish species richness was highest at site 4 while the lowest species richness was at site 1. The Shannon Weiner Diversity Index also supported that site 4 had the highest fish species richness while site 1 had the lowest species richness. The FRAI results indicated that different sites were in different Ecological Categories (EC). The ECs showed a trend from higher EC category upstream to lower EC category downstream. Site 1 had an EC of C followed by site 2 with an EC of C/D, site 4 with EC of D and then site 3 with the lowest EC of D/E. This might serve as an indication of decrease in habitat availability, increase of pollutants input and increase in stream modification. The CCA showed a weak correlation system variables and fish species. However, a strong correlation was observed between most metals and most fish species with the exception of Mesobola brevianalis Boulenger, 1908, Chiloglanis pretoriae Van Der Horst, 1931, Labeobarbus marequensis Smith, 1841 and Enteromius neefi (Greenwood, 1962). In conclusion, the water in the Steelpoort River is still in relatively good condition. However, increasing mining, industrial and agricultural practices in the catchment area results in increase of pollutants input into the river system. All the four selected sites were contaminated to some degree, with site 3 being the most affected site and site 1 being the least affected site. For this reason, it is important to continuously monitor the health status of the Steelpoort River and to educate the nearby communities who rely on this river for water supply about the quality of the water from the Steelpoort River. / DSI-NRF SARCHI (Ecosystem Health)

No description available.

Despite over four decades of research on deep-sea hydrothermal vent ecosystems, major gaps remain in our understanding of these systems. Knowledge of microeukaryote diversity, abundance, and involvement in ecosystem function lags far behind that of prokaryotes, and contributions of the non-endosymbiotic microbiome in faunal assemblages to ecosystem processes and overall hydrothermal vent microbial diversity are not known. This research addresses these gaps using high-throughput sequencing of 16S/18S rRNA genes and metagenomes from vent and surrounding non-vent habitats encompassing diffuse hydrothermal fluids, plumes, deep seawater, and microbes in assemblages of the foundation tubeworm species Ridgeia piscesae. Co-occurrence/covariance is a central method used, first, between prokaryotes with known extreme habitat preferences and microeukaryotes to infer potential endemism in the latter, and then between microbes and fauna in R. piscesae assemblages to infer interspecies interactions. Microeukaryote distribution and abundance suggest potential vent endemic microeukarya are infrequently encountered, potentially in low abundance, and belong to novel lineages of Rhizaria and Stramenopila. Potential endemism is inferred for relatives of known apusomonads, excavates, and some clades of Syndiniales. R. piscesae assemblages are shown to be hotspots of microbial taxonomic richness and exhibit a robust temperature-driven distinction in assemblage composition above and below ~25°C spanning micro, meio and macro size classes and microbial domains (Bacteria, Archaea, and micro-Eukarya). Likely interacting faunal and microbial taxa among R. piscesae assemblages are identified as ‘core communities’, which included eight macro- and meiofaunal taxa and members of the Bacteroidetes and Epsilonbacteraeota in highT communities (>25°C) and more meiofaunal species in addition to Alpha- and Gammaproteobacteria, and Actinobacteria in lowT communities (<25°C). Core communities were used to guide metagenomic investigations of microbial functional potential. Exploratory metagenomic analysis required development of new methods to deal with compositional data. ‘Enrichment leanings’ were developed to prioritize in-depth functional comparisons between sample types, which revealed clades within core community microbes with differing functional potential between highT and lowT assemblages and between assemblages and fluids. The balance of autotrophy-heterotrophy genes and patterns of genes for different carbon, nitrogen, and sulfur-cycling processes were tested as potential metrics of community-level function but did not distinguish assemblages by highT/lowT designations. This research brings us closer to understanding hydrothermal vent ecosystem function and suggests sizeable continued discovery potential. / Graduate / 2022-06-08

京都大学 / 新制・課程博士 / 博士(地球環境学) / 甲第24154号 / 地環博第232号 / 新制||地環||44(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)教授 柴田 昌三, 准教授 深町 加津枝, 教授 瀬戸口 浩彰 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

Although it is well documented how introduced species can negatively affect native species, we only poorly understand how they may alter ecosystem functions. We investigated how an invasive fish affected the flux of aquatic insects to terrestrial food webs using mesocosms in a desert spring ecosystem. We compared aquatic insect emergence between alternative community states with monocultures and polycultures of two native species of fish, least chub (Iotichthys phlegethontis) and Utah chub (Gila atraria) plus, introduced western mosquitofish (Gambusia affinis). We tested three hypotheses: (1) aquatic insect biomass will be greater than terrestrial insect biomass and thus, constitute a vital source of energy for terrestrial consumers (2) invasive mosquitofish will negatively impact the biomass of emerging aquatic insects, and (3) terrestrial consumers will negatively respond to decreased emerging aquatic insect biomass. Aquatic insects represented 79% of the flying insect community, and treatments with mosquitofish significantly reduced emergent aquatic insect biomass by 60% relative to the control without mosquitofish. Behavioral traits of invasive species are important, because mosquitofish most heavily affected insects that emerged during the day. Also, spiders that build horizontal webs were negatively correlated with decreasing aquatic insect biomass. Invasive mosquitofish can achieve very dense populations because of their high intrinsic rate of population increase, which can significantly disrupt the flow of energy between aquatic and terrestrial ecosystems, thereby reducing the energy available for terrestrial consumers.

Deep-sea benthic ecosystems remain poorly studied in South Africa, limiting understanding of community biodiversity patterns and their environmental drivers. This is one of the first studies to (i) visually investigate marine epifaunal community patterns and their environmental drivers along the Agulhas ecoregion outer shelf, shelf edge and upper slope to support marine ecosystem classification and mapping, and (ii) to determine the conservation targets for selected national marine ecosystem types to inform improved management of the marine environment, through Marine Spatial Planning processes. Visual surveys of the seabed were conducted to quantify epifauna during the ACEP Deep Secrets Cruise in 2016, using a towed benthic camera system. Twenty-nine sites were sampled, ranging from 120-700 m in depth and spanning the shelf-slope transition from the western edge of the Agulhas Bank to offshore of the Kei River mouth. A total of 855 seabed images were processed, and 173 benthic taxa quantified. Corresponding environmental variables were used to determine potential drivers of observed biodiversity patterns. Data were analysed using multivariate analyses, including CLUSTER, MDS and DistLM, in PRIMER v6 with PERMANOVA. Ten different epifaunal communities were classified and described with key characteristic taxa identified. Communities found in habitats that comprised mostly hard rocky substrata generally exhibited higher in species richness and were most commonly characterized by stalked crinoids, various corals and bryozoans, whereas communities found in habitats comprising unconsolidated sediment were lower in species richness and commonly characterized by polychaetes, cerianthids and brittle stars. Communities found in habitats comprising both hard and soft substrata had a mix of the above-mentioned epifauna. The distribution of these communities was mostly influenced by substratum type, longitude, trawling intensity, depth, and presence of visible particulate organic matter. The combined interactions of topography, substratum and the unique hydrodynamic conditions along the Agulhas ecoregion shelf-slope transition are likely responsible for the observed patterns. The observed community patterns were also compared to the existing classification of marine ecosystem types from the 2018 National Biodiversity Assessment. Fine-scale heterogeneity was revealed within the examined marine ecosystem types, particularly with substratum type and associated community variability and should be recognized and incorporated into future iterations of the national marine ecosystem classification and map. Species-area curves were used to calculate conservation targets for three ecosystem types, defined by the 2018 National Biodiversity Assessment, namely the Agulhas Coarse Sediment Shelf Edge, South West Indian Upper Slope, and the Agulhas Rocky Shelf Edge. Considering the epifaunal species richness (using the bootstrap estimator) and area, per image and per ecosystem type, the rate of accumulation of species was calculated and used to estimate the percentage of species expected to be represented by any given percentage of protected ecosystem type area. Between 20 and 30% of the area within these ecosystem types will need to be protected to represent 80% of the species. This study has shown that an integration of environmental parameters together with biodiversity measures to better understand and classify offshore benthic ecosystems has worked well. However, to improve the resolution of the national marine ecosystem classification and map, there needs to be greater input of fine-scale biological and environmental sampling and mapping of substratum types across the Agulhas ecoregion shelf-slope transition zone. This work is contributing to improvements in the national marine ecosystem classification and map and hence the spatial assessment and planning processes that rely on these products.