A combination of DGPS/GIS mapping, invertebrate surveys and environmental monitoring over one year (July 2004--July 2005) were used to examine the recovery of permanent tidal pools on a salt marsh in the lower Bay of Fundy which underwent an unmanaged restoration after breach of the dyke over 50 years ago. The results are compared to those of a nearby relatively undisturbed reference marsh. / Pools were found to represent a substantial portion of the marsh habitat, comprising 13% of the total marsh area in the recovering marsh and 4.8% in the natural marsh. Observations indicate ice may be an important mechanism of pool formation and growth in these marshes. Water temperature in the pools ranged from freezing (-2°C) to a maximum of 36°C with ice covering pools for up to one month in the winter. Salinity of the pools ranged from near freshwater (4) to hypersaline (41). Environmental variability was mainly driven by climatic conditions with increased tidal flooding of pools at low elevations tending to make the conditions more stable. / A total of 42 macroinvertebrate taxa were identified in pools of the two marshes, with species richness (S) of individual pools ranging from 13 to 23. An estimated 50 years since dyke failure, the invertebrate fauna of pools in the recovering marsh is indistinguishable from that of the reference marsh. No significant differences in macroinvertebrate communities were detected between sampling dates, pool size or pool depth. Non metric multidimentional scaling and hierarchical cluster analysis supported separating the pool invertebrate communities of this study into those occurring in regularly flooded pools, and those occurring in irregularly flooded pools. Average production of pool macroinvertebrates ranged from 1.79 to 4.03 g dry wt m-2, depending on the amount of vegetative cover in the pools. The pools are characterized by low equitability in species abundance and biomass. The numerically dominant organisms of the pools were mites (Acarina), the gastropod Hydrobia tottentei, Tubificidae oligochaetes, and Chironomus sp. larvae as well as copepods and ostracods.

Harvest-related decreases of downed woody debris (DWD) in forests may have important ecological implications; however, patterns of nutrient release from decaying DWD are poorly understood. The importance of DWD was investigated relative to biomass and nutrient pools in six, second-growth boreal mixedwood forest stands, differing by harvest regime near Kapuskasing, Ontario. Nutrient concentrations and mineralization trends using ion exchange resins at three proximities during the decay of Abies balsamea and Populus tremuloides were also examined. Concentrations of N, P, Ca, and Mg increased with decay, whereas K decreased. DWD was a minor contributor to biomass and nutrient pools. Inorganic N, P, Ca, and Mn were significant between harvest types with decay class interaction for N, Ca, and Mn. Species and proximity effects were found for Al, Fe, and K. These results suggest DWD may be a minor contributor to biomass and nutrient pools, but highlights its dynamic nature.

Harvest-related decreases of downed woody debris (DWD) in forests may have important ecological implications; however, patterns of nutrient release from decaying DWD are poorly understood. The importance of DWD was investigated relative to biomass and nutrient pools in six, second-growth boreal mixedwood forest stands, differing by harvest regime near Kapuskasing, Ontario. Nutrient concentrations and mineralization trends using ion exchange resins at three proximities during the decay of Abies balsamea and Populus tremuloides were also examined. Concentrations of N, P, Ca, and Mg increased with decay, whereas K decreased. DWD was a minor contributor to biomass and nutrient pools. Inorganic N, P, Ca, and Mn were significant between harvest types with decay class interaction for N, Ca, and Mn. Species and proximity effects were found for Al, Fe, and K. These results suggest DWD may be a minor contributor to biomass and nutrient pools, but highlights its dynamic nature.

Mire pools – shallow water-bodies in peat-forming wetlands – are a characteristic feature of New Zealand’s subalpine and alpine landscapes (>1000 m a.s.l.), yet have been the subject of few biological studies to date, particularly of their algal communities. This research focuses on these subalpine systems, and on their diatom communities. Despite the established paradigm of ubiquitous dispersal in micro-organisms, recent taxonomic studies have confirmed a distinctive endemic component in the freshwater diatom flora of the New Zealand / Tasmania / East Australian region. In this study, I examined benthic diatom communities from >320 freshwater sites throughout New Zealand and showed that over 20% of species may be confined to this region. The endemic diatom species had highest densities in stable, unproductive environments, particularly in high-altitude mire pools and tarns. In most cases, non-endemic taxa coexisted with endemic species. This raised questions about (1) the special characteristics of mire pools and tarns (since endemism might be expected in areas that have unique environmental characteristics), and (2) the mechanisms that have allowed existing endemic taxa to withstand displacement by common cosmopolitan taxa, which, by definition, are successful colonisers. I addressed these questions using two years of data from four subalpine mire pools (Bealey Spur wetland, near Arthur’s Pass, South Island). Physico-chemical data showed that water chemistry of these pools may differ from that of many Northern Hemisphere mire systems with respect to the relationship between pH and dissolved ions (especially calcium). This may be due to a combination of high pH rainfall, high rainfall quantities that limit the acidification effects of humic substances, and possibly vegetation differences. Therefore, some endemic taxa may be confined to these habitats because of the characteristic properties of the pools. I investigated the effects of disturbances in these stable environments. In the largest pool endemic species were shown to decline as wind-induced substrate disturbance increased. Endemic species also declined in two pools following small-scale experimental substrate disturbances. In all cases, non-endemic species remained unchanged. The distinctive species Eunophora cf. oberonica was responsible for much of the observed decline in endemic species abundances, which was evidently due to destruction of their specialised habitat within the cyanobacterial mats that made up the pool substrates. I explained pool-specific responses of diatom communities to disturbances by drawing on recent theory of invasibility as an intrinsic environmental property. I further investigated species coexistence by examining several general patterns of interspecific coexistence described for macroscopic organisms (e.g., abundance – occupancy, abundance – persistence). Patterns in mire-pool diatom communities were generally similar to those in larger organisms, and did not differ with respect to geographical range size (endemics vs. non-endemics), except at the scale of single pools. At this scale, endemic taxa, in particular E. cf. oberonica, can persist as dominant species. All the community analyses were underpinned by detailed taxonomic studies, from which I assessed over 40% of the more common species in the pools to be either endemic or likely to be endemic. Two species occurring in the study area are formally described as new species. Overall, this work highlights the vulnerability of this hidden component of New Zealand’s biodiversity to disturbances and environmental changes.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. Annie Clement, Florida State University, College of Education, Dept. of Sport Management, Recreation Management, and Physical Education. Title and description from dissertation home page (viewed June 13, 2005). Document formatted into pages; contains xi, 128 pages. Includes bibliographical references.

Thesis (doctoral)--Uppsala University, 2001. / Includes bibliographical references (p. 182-190).

Thesis (doctoral)--Uppsala University, 2001. / Includes bibliographical references (p. 182-190).

Alpine valleys are rarely closed systems, implying that the atmospheric boundary layer of a particular valley section is influenced by the surrounding terrain and large-scale flows. A detailed characterisation and quantification of these effects is required in order to design appropriate parameterisation schemes for complex terrains. The focus of this work is to improve the understanding of the effects of surrounding terrain (plains, valleys or tributaries) on the heat and mass budgets of the stable boundary layer of a valley section, under dry and weak large-scale wind conditions. Numerical simulations using idealised and real frameworks are performed to meet this goal. Several idealised terrains (configurations) were considered: an infinitely long valley (i.e. two-dimensional), and upstream valleys opening either on a plain (valley-plain), on a wider valley (draining) or on a narrower valley (pooling). In three-dimensional valleys, two main regimes can be identified for all configurations: a transient regime, before the down-valley flow develops, followed by a quasi-steady regime, when the down-valley flow is fully developed. The presence of a downstream valley reduces the along-valley temperature difference, therefore leading to weaker down-valley flows. As a result, the duration of the transient regime increases compared to the respective valley-plain configuration. Its duration is longest for the pooling configuration. For strong pooling the along-valley temperature difference can reverse, forcing up-valley flows from the narrower towards the wider valley. In this regime, the average cooling rate at the valley-scale is found to be a maximum and its magnitude is dependent on the configuration considered. Therefore pooling and draining induce colder and deeper boundary layers than the respective valley-plain configurations. In the quasisteady regime the cooling rate is smaller than during the transient regime, and almost independent of the configuration considered. Indeed, as the pooling character is more pronounced, the warming contribution from advection to the heat budget decreases because of weaker down-valley flows, and so does the cooling contribution from the surface sensible heat flux. The mass budget of the valley boundary layer was found to be controlled by a balance between the convergence of downslope flows at the top of the boundary layer and the divergence of the down-valley flow along the valley axis, with negligible contributions of subsidence far from the valley sidewalls. The mass budget highlighted the importance of the return current above the down-valley flow, which may contribute significantly to the inflow of air at the top of the boundary layer. A case-study of a persistent cold-air pool event which occurred in February 2015 in the Arve River Valley during the intensive observation period 1 (IOP1) of the PASSY- 2015 field campaign, allowed us to quantify the effects of neighbouring valleys on the heat and mass budgets of a real valley atmosphere. The cold-air pool persisted as a result of warm air advection at the valley top, associated with the passage of an upper-level ridge over Europe. The contributions from each tributary valley to the mass and heat budgets of the valley atmosphere were found to vary from day to day within the persistent stage of the cold-air pool, depending on the large-scale flow. Tributary flows had significant impact on the height of the inversion layer and the strength of the cold-air pool, transporting a significant amount of mass within the valley atmosphere throughout the night. The strong stratification of the near-surface atmosphere prevented the tributary flows from penetrating down to the valley floor. The evolution of the large-scale flow during the episode had a profound impact on the near-surface circulation of the valley. The channelling of the large-scale flow at night, can lead to the decrease of the horizontal temperature difference driving the near-surface down-valley flow, favouring the stagnation of the air close to the ground.

Foram coletadas amostras de água de piscinas térmicas e não térmicas na cidade de Porto Alegre, RS, Brasil entre os meses de maio de 2006 e março de 2007, com o objetivo de determinar a presença do gênero Acanthamoeba, bem como realizar a caracterização fenotípica e genotípica dos isolados. Amebas foram isoladas em cultivo monoxênico com Escherichia coli. A identificação dos isolados foi baseada na morfologia dos cistos e trofozoítos e na amplificação por PCR com oligonucleotídeos gênero-específico. O potencial patogênico foi avaliado usando testes de osmotolerância e termotolerância. Das 65 amostras analisadas, 13 (20%) foram positivas para amebas de vida livre e identificados morfologicamente como pertencentes ao gênero Acanthamoeba. Destas, 9 possuíam características compatíveis com o grupo morfológico II e 4 com o grupo III. Todos os isolados identificados morfologicamente quando submetidos à Reação de PCR, confirmaram pertencer ao gênero Acanthamoeba e 38% (5/13) dos isolados foram considerados potencialmente patogênicos a partir dos testes de osmotolerância e termotolerância. Neste estudo, o método molecular de RAPD ("Random Amplified Polymorphic-DNA") foi utilizado para investigar a relação genética entre os 13 isolados de piscinas e dois isolados de referência da ATCC. De 10 oligonucleotídeos decaméricos testados, quatro foram selecionados por gerarem produtos de amplificação passíveis de análise. A similaridade entre os isolados foi calculada utilizando-se o coeficiente de Jaccard e o dendrograma construído pelo método da média das distâncias entre grupos ("Average Linkage"). Quatro grupos distintos (G1-G4) de isolados foram formados de acordo com a similaridade genética entre eles. Sugeriu-se que os isolados do G1 por agruparem-se aos isolados de referência de A. castellanii (ATCC 30010 e 50492) possam pertencer a esta espécie. Os dados fenotípicos, tais como, morfologia e testes de tolerância foram relacionados aos dados genotípicos de RAPD e permitiram a caracterização dos isolados. Os resultados deste primeiro estudo de isolamento e caracterização de Acanthamoeba de água de piscinas na cidade de Porto Alegre-RS, Brasil confirmam a presença de isolados potencialmente patogênicos que podem representar um risco à saúde humana. / Water samples were collected from both heated and unheated swimming pools in the city of Porto Alegre, RS, Brazil between May 2006 and March 2007, to determine the presence of Acanthamoeba in the water of swimming pools as well as perform the phenotypic and genotypic characterization of the isolates. Amoebae were isolated in monoxenic culture with Escherichia coli. The identification of the isolates was based on the trophozoites and cysts morphology and on the amplification through PCR with genus-specific oligonucleotides. The potential pathogenic was assessed by osmotolerance and temperature tolerance assays. From the 65 samples analyzed, 13 (20%) were positive for free-living amoebae, and the isolates morphologically identified as belonging to the genus Acanthamoeba. Out of these, 9 presented characteristics compatible with morphological group II, and 4 with group III. All the morphologically identified isolates, when submitted to PCR, were confirmed as belonging to the genus Acanthamoeba, and 38% (5/13) of the isolates were considered potentially pathogenic according to osmotolerance and temperature tolerance assays. In this study, the molecular RAPD method (Random Amplified Polymorphic-DNA) was used to investigate the genetic relationship among 13 isolates from swimming pools and two strains from the ATCC reference. From the ten decameric oligonucleotides tested, four were selected for generating products of amplification possible to be analyzed. The similarity between isolates was calculated using the Jaccard coefficient and the dendrogram constructed by using the method of the average distances between groups ("Average Linkage"). Four distinct groups (G1-G4) of isolates were separated according to genetic similarity between them. It was suggested that the isolates from G1 once group up with the reference isolates of A. castellanii may belong to this species. The phenotypic data such as morphology and tolerance tests were related to RAPD genotypic data and led to the characterization of isolates. The results of this study about isolation and characterization of Acanthamoeba in swimming pools water at Porto Alegre, RS, Brazil confirm the presence of potentially pathogenic isolates which can present risks to human health.

Les mares forestières temporaires sont de petites zones humides d’eau douce, sujettes à de fortes dégradations. Le fonctionnement des mares naturelles et restaurées a été étudié en se basant sur les taux de décomposition de la matière organique (MO) et sur l’effet de facilitation d’une plante vasculaire (Molinia caerulea, molinie) sur la croissance des sphaignes (Sphagnum palustre). Les taux de décomposition de la MO dans l’eau ne différaient pas entre les mares naturelles et restaurées mais ils étaient influencés par la teneur en carbone organique du sol, l’ouverture de la canopée forestière et le couvert en sphaignes. Dans le sol de la zone de transition mare-forêt, ces taux étaient réduits par la saturation en eau et par un couvert molinie-sphaignes. La présence de la molinie diminuait la croissance des sphaignes, suggérant une compétition. Les résultats de cette étude contribuent à l’écologie de la restauration de ces mares et questionnent leur devenir dans un contexte de changement climatique. / Vernal pools are small freshwater wetlands, subject to strong degradations. The functioning of natural and restored vernal pools was studied, based on organic matter (OM) decomposition rates and the facilitation effect of a vascular plant (Molinia caerulea, purple-moor grass) on Sphagnum growth (Sphagnum palustre). The rates of OM decomposition in water were not different between natural and restored pools, but they were influenced by soil organic carbon content, tree canopy openness and Sphagnum cover. In the soil of the pool-forest transition zone, these rates were reduced by water logging and by a Molinia-Sphagnum cover. The presence of Molinia decreased Sphagnum growth, suggesting a competition relationship. The results of this study contribute to the restoration ecology of vernal pools and raise the question of their fate in the climate change context.