Dissertations / Theses on the topic 'Stress ecology'

Microbes are constantly exposed to a wide range of environmental stresses. To cope, all microbial species have developed protective mechanisms that can safeguard against potential damages due to stress. While stress protection is a beneficial contributor to microbial survival, it also carries a cost. The launch of a stress response diverts cellular resources to the synthesis of energetically expensive stress protectants. Consequently, responding and adapting to stress reduces growth in nutrient-poor environments. Hence the ability to balance allocation of available resources between stress protection and nutritional capacity in response to environmental signals is a fundamental property required for microbial survival with important consequences for species abundance and distribution in nature. This thesis deals with microbial survival strategies and their ecological impacts in two parts: First, we investigate the balance between stress-protection and nutrition as a driver of intra-species evolutionary divergence. Using a simple mathematical model we show that the protection-nutrition balance itself is sufficient to generate diversity within an initially monomorphic microbial population growing in a spatially homogeneous environment containing a single limiting resource. From experimental data we then estimate resource allocation between nutritional and stress resistant properties in glucose-limited E. coli chemostat populations subject to a range of environmental challenges and find that the evolutionary trajectories of multiple types can be predicted using the mathematical model. Second, we investigate the impact of inter-species differential survival strategies on microbial community structure within a Candida infection niche. Focusing on the lifestyles of Candida albicans and Candida glabrata under antifungal stress we build a mathematical model of niche competition within an infection. Calibrating the model using experimental data, we then generate predictions for the long term Candida ecology and find that the model is indeed predictive of equilibrium population distribution within a given infection niche.

Abstract The environment is now changing much faster than in recent geological time, causing increasing population extinctions. Experiments have shown that extinction can be avoided by adaptation through natural selection leading to evolutionary rescue. I first determined the response of Chlamydomonas to stressful environments by growing populations over a range of salinity. The population growth is halved at 5 g/L salt (NaCl), and 8 g/L is lethal. In this experiment, the genetic correlation between environments increases with environmental similarity. I then manipulated the genotypic diversity in experimental populations and cultured them by serial transfer at 5 g/L salt. The outcome of adaptation is not influenced by initial genetic variation. Instead, populations adapted mainly through the spread of new beneficial mutations. These results suggest that populations have a greater chance of adapting when new environments are similar to current conditions and that adaptation is sometimes dominated by the spread of new mutations, even in the presence of a substantial amount of standing genetic variation.
Résumé Notre environnement change maintenant beaucoup plus rapidement que dans le passé géologique récent, précipitant l'extinction de plus en plus d'espèces. Des chercheurs ont démontré que, grâce à l'adaptation par la sélection naturelle, des espèces peuvent éviter l'extinction, un processus nommé sauvetage évolutif. J'ai d'abord étudié la capacité de Chlamydomonas à croitre dans des environnements dont la salinité augmente. J'ai trouvé que 5 g/L de sel diminue la croissance de moitié tandis que 8 g/L est suffisant pour empêcher toute croissance. Ici, la corrélation génétique entre environnement augmente avec la similarité des environnements comparés. J'ai ensuite soumis des populations contenant différentes quantités de diversité génétique initiale à une salinité de 5 g/L. La diversité génétique initiale ne semble pas influencer la capacité d'adaptation. Cependant, les populations semblent plutôt s'adapter en utilisant de nouvelles mutations dont l'effet est bénéfique. Ces résultats suggèrent que les populations s'adapteront plus facilement à des environnements similaires aux conditions présentes. De plus, ce processus sera dominé par la fixation de nouvelles mutations, même dans des populations contenant de la diversité génétique.

I aim to determine whether or not remote sensing, through multispectral, satellite and digital photography, is a feasible and accurate method for determining drought stress in Fynbos vegetation. I hypothesize that (1) water stress in fynbos is detectable with the use of a remote sensing index, namely NDVI and (2) that the remotely sensed trends will correlate with ground truth measures of water stress.

Stress is a physiological state induced by disturbance or adverse environmental conditions and is modulated by the glucocorticoid hormone corticosterone (CORT) in reptiles. Stressors can have various impacts on vertebrate trait expression and may affect survival or reproduction. Little is known about the effects of chronically elevated CORT in free-ranging reptiles, or the effect of disturbance stress on venom composition in captive snakes. In chapter 1, we investigated the effects of researcher induced disturbance on CORT levels and venom composition in a group of captive Northern Pacific rattlesnakes (Crotalus oreganus). Venom protein concentration and plasma CORT levels were compared before and after two weeks of unpredictable bouts of cage vibration, and to a non-vibrated control group. CORT levels were also assessed one week into vibration treatment. We found no effect of vibration treatment on CORT levels or on venom composition, and within-snake relative protein abundance was highly repeatable, although some variation was observed. We found a strong correlation between changes in relative abundance of several proteins and CORT. These results led us to believe that while differential forms of researcher-induced disturbance may not affect venom composition, significant changes in baseline CORT, or chronic stress, may affect the venom phenotype. In the next study, we investigated the effects of chronically elevated CORT in a wild population of radio-telemetered Southern Pacific rattlesnakes (C. helleri). Snakes were implanted intra-coelomically with either crystalline CORT or sham implants. Prior to implant and for two week periods thereafter, we sampled blood, venom, defensive behavior, and body temperature (Tb). Thermal data logger implants recorded snake Tb each hour. Snakes were tracked daily for one month, and detectability, defensive behavior, movement, home range size and thermal parameters were calculated for each group during the periods between samples. Stress reactivity was assessed as change in CORT from baseline after one hour of acute confinement stress. CORT implants led to elevated baseline CORT for at least two weeks in treatment snakes, showing that our treatment was successful. Chapter 2 describes the effects of CORT treatment on venom parameters. Increased baseline CORT was associated with increased activity of venom protein phospholipase A2, indicating that CORT may have direct effects on regulating venom protein activity. Overall, venom activity was repeatable within individual snakes. Chapter 3 describes the effect of CORT on behavioral, ecological, and physiological variables. Implant treatment led to decreased average Tb in weeks two and three. We detected a trend for lower baseline CORT to predict a greater magnitude of acute stress response. Snakes with higher testosterone levels exhibited higher defensive behavior scores. Overall, there were no other effects of implant treatment. Our results suggest that rattlesnake thermoregulation is impacted by chronic stress, which could affect other aspects of their metabolism and ecology. Results of both studies suggest baseline CORT may direct both the activity and relative abundance of venom proteins in different manners, a hypothesis which deserves further investigation using proteomic tools. When responding to an acute stressor, rattlesnakes may secrete CORT until a threshold response is reached, regardless of baseline levels. Overall, rattlesnakes appear resilient to the effects of researcher-induced disturbance in the laboratory and to two weeks of chronically elevated CORT in the field, as no change was detected in many of the parameters investigated.

Questo progetto mira a studiare l’ecologia e la fisiologia di Seirophora villosa (Ach.) Frödén, specie epifita ritenuta in via di regressione a causa di una sempre più avanzata frammentazione del suo habitat preferenziale, il ginepreto costiero, habitat prioritario secondo la Direttiva 92/43 CEE (2250* “Dune costiere con Juniperus spp.”). La degradazione e la perdita dell’habitat in effetti sono ritenute le principali cause del declino delle popolazioni di S. villosa e recenti studi hanno evidenziato una correlazione positiva fra superficie locale dell’habitat e abbondanza di S. villosa. Tuttavia è stato dimostrato che, anche in situazioni ottimali, S. villosa non occupa tutto l’areale disponibile suggerendo una possibile implicazione di fattori ecologico/biologici limitanti la sua dispersione. Da queste considerazioni nasce questa ricerca che si propone di indagare sia a livello di popolazione che di individuo le caratteristiche che determinano la distribuzione di questa specie. Per raggiungere questi obiettivi abbiamo proceduto sia con esperimenti in campo che in laboratorio. In campo sono state valutate le relazioni che intercorrono fra le variabili strutturali del ginepreto e la diversità funzionale e specifica delle comunità licheniche epifite che lo ospitano e in particolare la relazione fra struttura dell’habitat e presenza di S. villosa. In laboratorio, sono stati indagati gli effetti delle principali variabili ecologiche sulla eco-fisiologia della specie al fine di caratterizzarne la nicchia ecologica. Abbiamo valutato le risposte fisiologiche della specie a cambiamenti di disponibilità della risorsa idrica e luminosa, in relazione alla dimensione dei talli. Inoltre, abbiamo indagato su di un carattere morfologico peculiare di questa specie, la pelosità del tallo, ipotizzando che questo carattere ricopra un ruolo primario nelle performance eco-fisiologiche della specie. Per indagare su questo aspetto abbiamo investigato eventuali meccanismi biochimici e fisiologici che la specie mette in atto per rispondere ed adattarsi alla presenza/assenza del pelo in superficie durante un ciclo di disidratazione e in presenza di stress salino. I risultati ottenuti dagli esperimenti a livello di popolazione mostrano che effettivamente un ginepreto continuo e strutturato porta ad una varietà e stabilità di microhabitat che supporta una forte differenziazione floristica e funzionale della comunità lichenica che lo ospita. Per quanto riguarda S.villosa, i nostri risultati confermano gli studi pregressi, evidenziando che le pratiche conservazionistiche per questa specie devono essere estese ad una scala ridotta, a livello di albero. I risultati di laboratorio mostrano che le dimensioni dei talli influiscono sulla capacità di ritenzione idrica dei questa specie; i campioni di S.villosa sono suscettibili ad una forte radiazione luminosa in particolare se questa è protratta nel tempo, in particolare i talli più piccoli che una volta fotoinibiti manifestano un’abilità di recupero piuttosto ridotta. Inoltre, i risultati confermano le nostre ipotesi a presenza dei peli sul tallo di S.villosa è risultato essere un tratto morfologico strategico per le performances di questa specie. La presenza del pelo offre un meccanismo passivo ma selettivo dell’acqua, regolandone l’assorbimento e la repulsione. Allo stesso tempo, aziona un meccanismo di resistenza passivo, di elusione dello stress, permettendo di tollerare la presenza di sale, in quanto ne impedisce l’entrata all’interno del tallo lichenico. Da un punto di vista pratico la conservazione della specie dovrebbe essere attuata garantendo le condizioni ideali a tutti gli stadi di crescita (ad esempio proteggere i propaguli dalla fotoinibizione). In caso di necessità di intervento valutare su scala locale la dinamica di popolazione e utilizzare questo dato per selezionare le aree e gli arbusti sui quali effettuare gli interventi.
Light regime, water availability and high salt concentrations are generally the main ecological factors modified by habitat fragmentation that could be detrimental to the survival and establishment of poikilohydric organisms such as lichens, causing rapid dehydration, ionic imbalances and the inhibition of photosynthesis. In the Mediterranean basin, coastal juniper habitats, priority habitat for nature conservation (Natura 2000 habitat code 2250), are known to host numerous epiphytic lichens, that living near the seashore need a morphological and chemical organization to adapt or acclimate to extremely variable disturbances. Among them, the macrolichen Seirophora villosa, which consists in a fruticose habitus characterized by the presence of compressed canaliculated laciniae covered by thin hairiness and the absence of secondary surface metabolites. Recently studies, has demonstrated the dependence of S. villosa on undisturbed Juniperus stands suggesting a significant effect of disturbance on the presence of this lichen species. Moreover, it has been demonstrated that S. villosa is only occupying a small part of its colonizable niche because of a very limited propagation ability. Since the presence and abundance of S.villosa are positive indicators of the conservation status of coastal nurseries, our study aimed to evaluate the effects of the main ecological variables on the eco-physiology of this species. Our first aim was to investigate whether the habitat structure affects the functional diversity and species richness of lichen communities along a coastal dune system and how affects the presence of S. villosa. Our second aim was to investigate how light regime and water availability affect individual specimens of S. villosa, by studying the relationship between photosynthetic activity and water content to thallus area in different sized. Furthermore, we investigated the role of the thin hairiness on thallus surface characterizing S. villosa to withstand the effects of seawater by continuous exposure to marine aerosol. Our results showed that epiphytic lichens richness and habitat width used as proxy of habitat integrity. Juniperus stands with higher individuals and cover continuity, probably ensuring a major stability of microclimatic factors, supported richer and functionally more differentiated epiphytic lichen communities. In contrast, the presence of S. villosa resulted not directly related to the habitat structure, suggesting a major role of dispersal and establishment capability therefore suggesting a management tailored at the tree-level aimed to the conservation of mature (apotheciate) specimens. However, ongoing research indicate a possible role of microhabitat structure on the abundance of this species. The experiments carried out showed that the size of the thalli influence the water retention capacity of S.villosa species, and consequently influence responses to strong exposure to light. Our outcomes showed that S. villosa are susceptible to sudden increases in light exposure, especially in the case of small specimens, which after photoinhibition exhibited a reduced ability to recover. Moreover, our work evidenced for the first time the relevance of hair as a strategic morphological trait in lichens to face extreme environments. Our results suggest that hair could offer a passive, but selective, water control. Furthermore, hair could repel the salt dissolved in water, by activating a passive resistance mechanism, a real avoidance of stress, which by not allowing salt to enter, allows the thallus to tolerate the presence of salt. In conclusion, from a conservation point it would be necessary to preserve all the growth stages of the population, providing a suitable habitat for the larger thalli that have the role of propagate the species and for the smaller ones giving them the opportunity to colonize and establish in fragment habitat without being photohinbited.

Global climate change has become an increasing source of concern due to the recent build-up of greenhouses gases in the atmosphere. The rocky intertidal zone, as the interface between land and sea, is particularly vulnerable to climate change. Many inhabitants of the intertidal zone are sessile and thus experience both terrestrial and aquatic lifestyles at low and high tides, respectively. When emersed at low tide, organisms experience a number of abiotic stresses including heat stress, desiccation stress, and low oxygen availability. Most intertidal organisms have evolved from marine animals and respire most efficiently in water. Barnacles are one such type of intertidal organism. At low tide barnacles face a tradeoff between access to oxygen and loss of water through evaporation. In this study, individuals of the species Balanus glandula, a common intertidal barnacle, were exposed to temperatures of 16°C, 24°C, 30°C, and 35°C for four hours in simulated low tide to determine when aerial respiration occurred. Oxygen levels were measured over the four hours of the exposure and oxygen consumption rates were calculated. Oxygen consumption occurred at all temperatures studied, but the rates at different temperatures were not significantly different from each other. The results showed that barnacles can conduct aerial respiration over the entire course of the low tide exposure despite the risk of desiccation. This indicates that ATP demand remains substantial throughout the low tide and that resorting to anaerobic respiration is not sufficient to meet metabolic needs during low tide exposure.

Climate change models predict increased frequency and intensity of extreme thermal events, suggesting that exposure to stressful high temperatures will likely become more common for many organisms. I investigated how frequency of exposure to sublethal temperature stress impacted the relative shell growth and size-specific tissue mass of the California mussel, Mytilus californianus . Mussels were exposed in the lab to 32 °C during simulated low tides 0, 1, 4, or 7 days per week for eight weeks or transplanted into rocky intertidal plots exhibiting a range of thermal conditions in the field for 12 weeks, then challenged with repeated exposures to a more extreme temperature (36, 39, or 42 °C) for 5 sequential days. As predicted by theory, increased frequency of exposure to sublethal heat stress invoked a cost to individuals, expressed as reduced shell growth or size-specific tissue mass, but also resulted in higher survival following subsequent exposure to potentially lethal temperatures.

In this dissertation, I asked how soil biota, abiotic stress, and plant provenance influence plant communities and interactions between plants. Soil biota can have positive or negative effects on individual plants, and also influence the diversity and productivity of plant communities through their net effects on individuals and by mediating plant-plant interactions. However, the level of abiotic stress experienced by plants is likely to drive plant responses to soil mutualists and antagonists. Additionally, plant provenance (e.g. population origin) can influence responses to abiotic soil conditions as well as to soil organisms. Understanding how these three interacting components shape plant interactions may improve success of restoration and invasive plant management. During restoration, the goal is typically to create conditions conducive to native plant reestablishment. However, amelioration of disturbed areas by reducing abiotic stress or by adding beneficial soil organisms may unintentionally increase colonization and growth of non-native plants. Using the applied context of mine restoration, I examined how soil biota, abiotic stress, and plant provenance affected plant communities and interactions in four studies.

In Chapter 1, I found that both a native grass (Bouteloua gracilis ) and an invasive grass (Bromus tectorum) responded positively to soil biota when grown alone in the greenhouse. However, when grown together, the presence of soil biota increased the competitive ability of Bromus, while the removal of soil biota increased competition by Bouteloua. Results supported the hypothesis that invasive species such as Bromus often have positive responses to soil biota in the invaded range, but I also found that Bromus response to soil biota removal varied considerably by site.

In Chapters 2 and 3, I examined how methods used during restoration (application of stockpiled soil and inoculation with soil biota) affected native and non-native plant growth in field plots. I found that native plant biomass and non-native plant biomass both tended to increase when soil abiotic stress was ameliorated through the addition of deeper stockpiled soil. In addition, both native and non-native grasses responded positively to the use of local soil an as inoculant, while non-native forbs responded negatively to local soil inoculum. However, native plants only received significant benefits from inoculation when targeted application to native seedling transplants was used. Commercial mycorrhizal fungal inoculum did not affect plant growth. In studies of both stockpiled soil addition and soil inoculation, year was an important factor in determining plant responses. Variation in effects by year may reflect differences in precipitation timing or amount, or changes associated with plant and soil biota growth over time.

In Chapter 4, I used a greenhouse experiment to examine how one type of soil biota, arbuscular mycorrhizal fungi (AMF), influenced plant-plant interactions. I also manipulated abiotic stress (soil phosphorus availability) and plant provenance (stress-tolerant ecotype versus competitive ecotype) to assess whether these factors influenced AMF-mediated interactions among plants. I found that allowing or denying AMF hyphal access between neighboring pots altered plant reproduction. Inflorescence production was substantially decreased when hyphal access was allowed between two stress-tolerant plants. In addition, when hyphal access was permitted from a stress-tolerant plant to a competitive plant, the competitive plant flowered slightly sooner, whereas allowing hyphal access between two stress-tolerant plants led to slightly slower flowering. These results did not appear to be driven by abiotic stress or plant nutrition. It is possible that AMF transmission of infochemicals may play a role in regulating plant phenology and reproduction; however, further research in this area is needed.

Lipid quality was evaluated in Montastrea spp. under sediment- and heat-stressed conditions to evaluate lipid ratio as an indicator of sub-lethal stress on short time scales. The ratio of storage lipid (wax ester + triacylglyceride) to structural lipid (sterol esters + phospholipid) decreased significantly (0.25 to 0.14, p < 0.01) after experimental sedimentation. FAME analysis of colonies exposed to experimental sedimentation showed a reduction of the algal, 18:3(n-6) and 18:4(n-3), polyunsaturated fatty acid (PUFA) in the polar lipid fraction. This loss of PUFA suggests a loss of algal membrane in sediment-stressed colonies. Lipid quality was similarly measured in M. faveolata over a 10-day period. Mean (n = 20) ratio of storage to structural lipid in M. faveolata dropped from 2.43 to a level of 0.98 immediately following a natural sedimentation event before recovering to levels of 1.4 and 2.9 on post-storm days 2 and 4, respectively. Colonies of M. annularis subject to heat-stress (35??C) exhibited no significant change in storage lipid ratio, while levels of Free Fatty Acids increased significantly from 0.012 (n = 22) to 0.156 mg lipid/g dry tissue (n = 22)(p < 0.05). FAME analysis of tissue lipids extracted from the heat-stressed colonies showed changes in the polar fraction, with significant decreases in the 18:3(n-6), 18:3(n-3), 18:4(n-3), 20:4(n-6) and 20:5(n-3) (p < 0.05) PUFA and subsequent significant increases in the saturated fatty acids, 16:0 and 18:0 (p < 0.05). These changes in lipid quantity and quality indicate possible oxidation and preferential digestion of zooxanthellar membranes. Stress experiments were repeated in M. annularis using VacutainerRTM blood collection tubes to collect micro-tissue samples without destroying skeleton of the sample colonies. A significant decrease in storage: structural lipid ratio after sedimentation was also detected using the micro-tissue technique. This study indicates that the relative abundance of lipid subclass components can indicate sub-lethal environmental stress, on short time scales, in M. annularis and M. faveolata. Furthermore, micro-tissue collection techniques permit repeated monitoring coral colonies to assess the manifestation of stress from first detection of impact at the cellular level to changes in community to changes in community structure detectable over longer time scales.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007.
Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5693. Adviser: Ellen D. Ketterson. Title from dissertation home page (viewed May 8, 2008).

Personality, that is intra-individual consistency and inter-individual variation in behaviour, is widespread throughout the animal kingdom. This challenges traditional evolutionary assumptions that selection should favour behavioural flexibility, and that variation in behavioural strategies reflects stochastic variation around a single optimal behavioural strategy. Adaptive models to explain personality within the framework of evolutionary and behavioural ecology exist, and are typically empirically explored by identifying proximate associations to, and the functional consequences of, personality expression. To date, such studies have typically quantified a narrow range of personality traits within a species, and focused on captive populations or species with relatively limited behavioural or social repertoires. In this thesis, personality is studied in wild Barbary macaques (Macaca sylvanus). Quantification of personality structure in the species was conducted using a multi-method approach, and subsequently, it was examined whether physiological stress response (a proximate association) was related to personality expression, and whether personality expression affected social (functional) outcomes for individuals. Seven personality constructs were identified in Barbary macaques. Three personality constructs were related to physiological stress responses (Excitability, Tactility and Exploration), with the relationship between stress and personality expression dependent on sex, and in some cases rank or age. Two personality constructs (Excitability and Exploration) were associated with measures of social integration. Subjects generally socially assorted themselves according to personality, tending to be in proximity to individuals with a similar personality to themselves. This study contributes methodologically by demonstrating the plausibility of multi-method approaches to measuring personality in wild primates, and empirically, by generating evidence supporting adaptive models for the evolution of personality, namely that intra-individual consistency in behaviour may be mediated by physiology and that inter-individual variation in behaviour has functional benefits in the formation of social relationships and social structures.

The focus of this thesis is the early detection of stress in the environment. It has been proposed that studies on the cellular level would detect stress reactions earlier in time compared to common physiological methods. In a series of experiments we investigated how different stress factors, both natural and introduced by man, affect levels of stress proteins. One- and two-dimensional gels were used to determine individual proteins and families of proteins. The two-dimensional gels were also used in a proteomic approach, were the presence and absence of proteins after treatment was observed, and the protein expression signatures (PES) were identified.

Baltic Mytilus edulis was used in all experiments and it is evident that earlier observed differences in physiological rates and pollution sensitivity, compared to marine mussels, is also manifested as lower concentrations of stress proteins after exposure to copper and cadmium. When the Baltic mussels were allowed to acclimate for one month the difference decreased, suggesting an environmentally induced difference (paper I). Pre-exposure to heat before exposure to either a second heat-shock or cadmium was found to enhance the levels of HSP70 and thus tolerance, significantly (paper II). Exposure to a mixture of stress factors (PCB, copper and lowered salinity) revealed synergistic, additive and antagonistic effects in induction of 6 different stress proteins. When analyzing a large number of proteins it was shown that it is possible to identify PES with this technique, and we hypothesize that it could be possible to separate responses to mixtures of stress factors (Papers III and IV). Different techniques were also applied to analyze the protein expression pattern when mussels were exposed to PAH- and PCB-fractions extracted from Baltic Sea sediments. In this experiment the protein assays were accompanied by physiological measurements. All methods indicated stressed conditions, but the variation between individual mussels within treatments was smaller in terms of protein response than for physiological parameters (paper V). It is concluded that measuring the induction of stress proteins is a reliable way to detect stressful conditions. Proteins visualized on a one dimensional gel give a “gross” picture of an organism’s condition. The major challenge is to identify the origin and severity of the elucidated stress response. Further mapping of two-dimensional gels suggested that protein patterns are specific to type and level of stress.

A most important future step is to establish links between sub-cellular protein response to well known physiological effects. This should include long term experiments where altered protein expression signatures are linked to life history characteristics like survival, growth and reproductive success.

En aquesta tesi presento quatre capítols, en els quals es discuteix com diferents espècies subarbustives interactuen amb plantes coexistents, sota règims variables d’estrès. Aquesta recerca ha estat centrada en ecosistemes de gran valor ambiental, ecològic i de conservació, i alhora sensibles als canvis ambientals, en quatre regions distintes situades en zones de latitud o altitud elevades. Per ordre latitudinal, els ecosistemes estudiats han estat: 1) el límit supraforestal dels Pirineus Centrals, situats en una zona temperada; 2) el gradient de successió primària d’un ecosistema situat en una zona boreal, a Finlàndia,; 3) el límit supraforestal situat a la zona subàrtica de Lapònia; i 4) la tundra situada en una zona de l’alt àrtic, al nord‐est de Grenlàndia . Els dos primers capítols es basen en una aproximació experimental i se centren en investigar com els subarbustos més comuns trobats prop del límit supraforestal interactuen amb plançons d’arbres de les espècies que formen el límit del bosc en dos ambients contrastats, i.e. el límit supraforestal subàrtic, i el límit supraforestal dels Pirineus Centrals. A més, donat que els arbres que viuen prop del límit de distribució són molt sensibles als canvis ambientals , especialment a l’augment de temperatures durant l’estació de creixement (Körner 2003), també s’ha investigat com podrien afectar el creixement dels plançons d’arbre i la seva supervivència al llarg de l’ecotò, diferents escenaris de canvis ambientals. El primer capítol es titula ‘Les interaccions arbre‐arbust i els canvis ambientals dirigeixen la dinàmica supraforestal a la zona subàrtica’, i s’hi exposa l’experiment de tres anys de durada que es va executar al ‘Parc Nacional d’Abisko’, en els Scandes subàrtics, al nord de Suècia; les plantes estudiades varen ser plançons de Betula pubescens i el subarbust Vaccinium myrtillus. En aquest estudi es va certificar la importància de les interaccions arbust‐arbre, tant facilitatives com competitives, com a elements clau en la dinàmica supraforestal subàrtica. A més, vàrem demostrar que la gran sensibilitat dels plançons a l’escalfament tenia fortes implicacions per la dinàmica supraforestal, tenint en compte l’escenari previst d’augment de temperatures en latituds elevades. També es va observar que les interaccions complexes entre arbusts i herbívors són claus per preveure canvis futurs. El segon capítol es titula ‘Els plançons d’arbres situats als límits supraforestals Pirinencs i subàrtics mostren respostes semblants a la presència d'arbustos i a les simulacions de canvis ambientals’. Aquí es presenta una comparació entre els resultats de l’experiment presentat en el primer capítol i els obtinguts en un experiment paral∙lel dut a terme durant un període de temps semblant prop del límit supraforestal en el ‘Parc Natural de l’Alt Pirineu’, als Pirineus Centrals catalans. Aquest experiment es va basar en el mateix disseny factorial que l’anterior estudi, però amb diferents espècies (i.e. plançons de l’arbre Pinus uncinata i l’arbust Rhododendron ferrugineum). Segons ens consta, és el primer estudi que avalua experimentalment les respostes de les plantes vers diferents escenaris ambientals en un ecosistema d’alta muntanya als Pirineus. En aquest capítol es presenten alguns mecanismes que ajudaran a comprendre la variabilitat recentment observada de les respostes locals de límits supraforestals de zones temperades i subàrtiques com a resultat del clima canviant, i també identifiquem alguns paral∙lelismes que poden utilitzar‐se per generalitzar les respostes a gran escala dels límits supraforestals al canvi climàtic. El tercer capítol se centra en els efectes d’un subarbust dominant (i.e. Empetrum nigrum) en plançons de Pinus sylvestris al llarg del gradient de successió primària en un ecosistema boreal en una illa emergent de la badia de Bòtnia, a Finlàndia. Aquest capítol s’anomena ‘Un arbust ericoide exerceix la doble funció de reclutar pins i els seus simbionts fúngics al llarg d’un gradient de successió primària’. Aquí hem mostrat que els efectes facilitadors i competidors dels subarbustos determinen fortament l’establiment de plançons i la seva colonització fúngica al llarg d’aquest gradient de successió. Segons ens consta, aquests són els primers resultats que demostren que un arbust ericoide micorrízic pot millorar tant el desenvolupament de l’arbre hoste ectomicorrízic com el dels simbionts fúngics de l’arbre. L’estudi presentat al quart capítol es va realitzar al llarg d’un gradient de nivositat en un ecosistema extrem de tundra àrtica al ‘Parc Nacional del nord‐est de Grenlàndia’, el Parc Nacional més gran del món. El capítol es titula ‘Interaccions vegetals i composició de la vegetació àrtica al llarg d’un gradient de nivositat al nord‐est de Grenlàndia’. Aquest ecosistema és probablement el més sensible i fràgil de tots els ecosistemes estudiats en aquesta tesi, donat que s’espera que a la costa est de Grenlàndia s’hi esdevinguin canvis substancials en el clima com a resultat de canvis destacables en els règims de precipitació de neu i de les temperatures (Brown i Mote 2009). Aquí es va avaluar la riquesa d’espècies de plantes, així com els patrons d’establiment i composició de diverses formes de creixement existents en comunitats vegetals àrtiques associades a una variació de la cobertura de neu durant els mesos d’hivern. Aquest estudi ajudarà a preveure la diversitat potencial i els canvis en la vegetació a la zona de l’alt Àrtic, si els règims de precipitació de neu canvien en el futur com es preveu.
In this thesis I present four chapters, and in all of them I discuss how dwarf shrubs interact with co‐occurring plants under varying regimes of stress. This research involved ecosystems of great environmental, nature conservation and ecological value, yet highly sensitive to environmental changes, in four contrasting cold regions at high altitude or high latitude. Following a latitudinal order, the selected ecosystems were: 1) a temperate alpine treeline in the Central Pyrenees; 2) a primary succession gradient in a boreal ecosystem in Finland; 3) a subarctic alpine treeline in Lapland; and 4) a high‐arctic tundra in north‐eastern Greenland. The first two chapters are based on an experimental approach and focus on how shrubs commonly found near the treeline interact with tree seedlings of treelineforming species in two contrasting environments, i.e. in a subarctic forest‐tundra ecotone in Lapland, northern Sweden, and in a more southern, temperate forestalpine pasture ecotone in the Central Pyrenees. In addition, since trees living near their limit of distribution are very sensitive to environmental changes, especially to increased temperature during the growing season (Körner 2003), we also assessed how distinct environmental change scenarios may affect tree seedling growth and survival across the ecotone. The first chapter is entitled ‘Shrub‐tree interactions and environmental changes drive treeline dynamics in the Subarctic’, where we explain the three‐year‐long experiment performed in the Abisko National Park, in the subarctic Scandes, Northern Sweden; the species studied were Betula pubescens tree seedlings and the shrub Vaccinium myrtillus. In this study we showed the importance of facilitative and competitive shrub‐tree interactions as drivers of subarctic treeline dynamics. Furthermore, we demonstrated that the great sensitivity of tree seedlings to warming had strong implications for treeline dynamics under the predicted warmer scenario at high latitudes, and we identified that complex interactions between shrubs and herbivores are critical to predicting future changes. The second chapter is entitled ‘Similar tree seedling responses to shrubs and to simulated environmental changes at Pyrenean and subarctic treelines’. Here we presented a comparison between the results obtained in the experiment presented in the first chapter and those obtained in a parallel experiment performed during a similar period near the treeline in the Alt Pirineu Natural Park, in the Central Pyrenees, Catalonia. This experiment was based on the same factorial design but with different species (i.e. Pinus uncinata tree seedlings and the shrub Rhododendron ferrugineum). To our knowledge, it is the first study which experimentally tests the responses of plants to distinct environmental scenarios in a high mountain ecosystem in the Pyrenees. In this chapter we presented some mechanisms for understanding the recently observed variability of local responses of both subarctic and alpine treelines to currently changing climate while identifying some commonalities that can be used to generalise large scale response of treelines to climate warming. The third chapter focuses on the effects of a dominant dwarf shrub (i.e. Empetrum nigrum) on Pinus sylvestris tree seedlings along a primary succession within a boreal ecosystem on an uplifting island in Bothnian Bay, Finland. This chapter is called ‘An ericoid shrub plays a dual role in recruiting both pines and their fungal symbionts along primary succession gradients’. Here we showed that facilitative and competitive effects of shrubs markedly determined tree seedling establishment and their fungal colonisation along this succession gradient, but in this chapter we did not relate these findings to any environmental changes. As far as we know, we presented the first finding that an ericoid mycorrhizal shrub may enhance both the performance of the ectomycorrhizal host tree and the tree’s fungal symbionts. The study presented in the fourth chapter was performed along a snow‐depth gradient in an extreme arctic tundra ecosystem in the Northeast Greenland National Park, the largest national park in the world. The chapter is entitled ‘Plant interactions and higharctic vegetation composition along a snow‐depth gradient in NE Greenland’. This ecosystem is probably the most sensitive and fragile among the ecosystems studied in this thesis as the eastern coast of Greenland is expected to experience substantial changes in climate due to marked changes in snow precipitation and temperature regimes (Brown and Mote 2009). Here we assessed plant species richness, establishment and composition patterns in distinct growth forms occurring in common arctic plant communities associated with varying snow‐depth during the winter season. This study will help to predict potential diversity and vegetation changes in the high Arctic if snow precipitation regime changes in the future as anticipated.

This thesis is an attempt to describe how different environmental factors influence life history traits in different populations, sexes and developmental stages in the moor frog, Rana arvalis. The studied populations are located along 1100 km latitudinal gradient, with pH varying between 4.0 and 8.5. I have used data from both natural populations and common garden experiments.

Reproducing moor frogs were larger and older at high latitudes, indicating a selective advantage of large size at high latitudes and/or earlier reproduction at low latitudes. When controlling for age I found that frogs were older and smaller at low pH, which may be a result of a reduced growth rate due to acid stress. The both sexes respond differently to different environments, with the lowest sexual dimorphism in body size found in the acid environments. This is possibly caused by a trade-off between growth and reproduction. Being large is considered to be advantageous, in females due to increased fecundity, and in males due to higher ability to compete for mates, while the cost of high growth is a reduced possibility to survive until the next mating season. Moor frog embryos originating from an acid population survived better under acid stress than embryos from a neutral population. Using quantitative genetic techniques I found strong maternal effects and small additive genetic variation for the traits in acid and non acid populations. The variation in acid stress tolerance owed largely to non-genetic effects. Females from acid localities lay larger eggs, which probably improves the performance of tadpoles under acid conditions. The trade-off between egg size and fecundity was stronger in acid populations indicating that females in acid populations reduced fecundity to increase offspring size. Finally, frogs from acidified environments were more asymmetric in skeletal traits further indicating the developmental stress created by acidification.

Gamefish populations in North America are experiencing increasingly elevated recreational fishing pressures; however, the impacts of current fishing regulations have not been evaluated for most marine species. Mandatory catch and release often results from size and bag limits with the assumption of fish survival and recovery with minimal sublethal effects. Depending on the intensity and duration of the stressor, acute stress from angling and handling can have deleterious physiological and behavioral impacts with consequences for fish health and fitness. We evaluated the short-term sublethal effects of angling-related stressors on kelp bass, Paralabrax clathratus, one of the most popular gamefish in southern California. Collaborating with recreational anglers to capture fish using standard hook and line practices, we evaluated biochemical responses and recovery by collecting blood samples at different time points after capture (10-120 min), after fish were released and some were recaptured (3h to 186 d). Blood cortisol, glucose, and lactate were significantly elevated and steadily increased in the hour following capture and holding (p < 0.001). Fish caught, released, and recaptured after varying time at liberty were found to have returned to basal levels in < 24 h (p > 0.05). Physiological stress responses were positively correlated with angling and handling duration, but negatively correlated with increasing fish size (p < 0.05), suggesting that larger individuals may be more resilient to capture stress. Likewise, kelp bass exhibited no signs of cumulative or chronic stress from repetitive angling/recapture events and recovered to basal levels in <24 h (p > 0.05). Kelp bass were also tagged with acoustic accelerometer transmitters and tracked to evaluate fine-scale behavioral effects of angling stress on their normal diel movement and activity. Reduced frequency of high acceleration movements (i.e. rapid feeding strikes) was observed for 33 h post-release, followed by recovery and evidence of elevated feeding behavioral activity. Rate of movement and area use size showed high individual and temporal variation; however, reduced movement immediately after release steady increased to normal levels over the first 10 h post-release. There was no discernable effect of angling on area use size, but areas of high relief substratum may be important refuge habitat for angled kelp bass during recovery. By integrating physiological and behavioral endpoints for kelp bass to standard angling induced stress we conclude that this species is able to recover in <24 h; however, smaller individuals may be more susceptible to predation during this recovery period. Based on these findings, it is likely that kelp bass may still fair well under current size and bag limits.

Community models predict the effects of stress on community structure and processes. I tested the Menge and Sutherland 1987 model in an estuarine epifaunal community experiencing low oxygen stress, termed hypoxia. Epifauna, animals living on the surfaces of substrates, are ecologically important in many estuaries where hypoxia occurs, yet little is known about the effects of hypoxia on these communities. Epifauna formed dense communities in the York River, a tributary of the Chesapeake Bay, USA, despite frequent hypoxia. Abundance and species composition was similar in two areas of the river, even though the downstream study area often experienced lower oxygen concentrations during hypoxic episodes than the upstream study area. Many dominant species exposed to high and low oxygen in the laboratory had a median lethal time (LT50) in hypoxia greater than the duration of typical hypoxic episodes in the York River, suggesting that hypoxia may cause little mortality for many species in this system. Predation by a variety of taxa decreased during hypoxia in the laboratory, because many mobile predators had higher mortality than sessile prey, and because predation rates decreased. Peak recruitment of dominant taxa, and of total epifauna, in the York River occurred during neap tides in the downstream study area, coinciding with the lowest oxygen concentrations. In the laboratory, low oxygen decreased recruitment of dominant taxa, but some recruitment continued in hypoxia for most taxa, indicating that larvae of dominant epifauna are tolerant of hypoxia. Larval tolerance of hypoxia may allow communities to persist even though the recruitment season of many epifaunal species coincides with the peak season of hypoxia. These findings supported some predictions of the consumer stress model, but not all. as predicted, when stress increased, the importance of disturbance for determining community structure increased, while the importance of predation decreased. Unlike predictions, stress changed recruitment rates in the laboratory. There were few effects of stress on abundance and diversity, possibly because in this system hypoxia is mild, brief, and because the species in this community can tolerate stress, colonize disturbed areas quickly, and grow quickly enough to complete life-cycles between hypoxic episodes.

Natural stress and disturbances are important factors affecting the structure and function of ecosystems. However the magnitude of stress has escalated due to anthropogenic activities. Environmental monitoring and toxicity assessments try to protect ecosystems from unwanted human alterations. The aim of this Doctoral thesis was to increase the understanding of the complex effects that environmental stress has on individuals and invertebrate populations. The low saline environment in the Baltic Sea is perceived as stressful for most organisms living there. In Paper I, it was found that Baltic blue mussels living in the less saline northern Baltic Proper (~5 psu) had lower basal metabolism and were more susceptible to toxic exposure than the mussels in the south (~7 psu). There was no genetic differentiation between the mussels from the northern and southern areas while there were genetic differences between mussels from sites within the respective areas (Paper III), indicating that there is not a simple relationship between the health of the mussels and genetic diversity in the microsatellite loci studied. In Paper IV it was found that the heat tolerance of the intertidal dogwhelk Nucella lapillus is oxygen dependent. Increased oxygen levels resulted in higher survival rate. Protein expression profiles also became more similar to those of the controls, compared to the whelks exposed to high temperature and normal oxygen levels. In Paper V and VI it was found that exposure to a single toxicant for more than one generation decreased the genetic diversity in exposed copepod populations even though abundances remained unaltered. In Paper VI, exposure to naturally contaminated sediments, which contained of a mixture of toxicants, did not decrease genetic diversity. However the genetic divergence (FST) within the treatments was very high, probably due to small effective population sizes in the replicates. Likewise in Paper III, the very low blue mussel abundance in the north together with the stressful environment suggests a small effective population in the northern Baltic Proper. In conclusion, my studies show that, measuring effects on several levels, including both functional and structural endpoints will both increase the sensitivity of the tests and increase their ecological relevance.

Every organism needs to survive and successfully reproduce in the face of changing environmental conditions in which variation in resource availability can seriously limit performance. Organisms can respond to the variation in quality or availability of food resources with behavioural and physiological accommodations going from the baseline physiological response to environmental stressors to complex life-history strategies like migration and diapause. In insects, one avenue to cope with the resources’ variation is to plastically tune the reproductive system to the environmental conditions in order to shift resources away from reproduction during unfavourable periods but maximize it when resources are abundant. I studied the role of reproductive physiology in both males and females in mediating a response to challenging conditions determined by a lack of food resources or the presence of qualitatively different diets using the milkweed bug, Oncopeltus fasciatus, as model species. I studied the role of oosorption, a plastic physiological response through which resources can be recovered and redirected to body maintenance and survival, in shaping behavioural strategies to cope with challenging environments. I also studied the effects of diet quality on male’s sexual behaviour and how these modulate the trade-offs between reproduction and survival. I then investigated how the effects of diet quality, sexual maturation and rearing conditions influence the occurrence of reproductive diapause in both males and females. I found that females exposed to different diets plastically adapt their schedule of reproduction depending on diet quality: this also influences the occurrence of oosorption in the ovary mediating the amount of resources that are directed to reproduction or survival. Diet quality influences males’ sexual behaviour so that even after a long-term adaptation on an alternative artificial diet, they invest more in reproduction at the expenses of survival when fed on an ancestral high quality diet; this is achieved with a shift in the trade-off between reproduction and survival. The occurrence of reproductive diapause in both males and females is a function of several factors: the quality of food resources ultimately modulates sexual maturation in adult individuals determining the occurrence of diapause or reproduction. Finally, oosorption may be involved in the evolution of alternative condition-dependent strategies as an adaptive physiological mechanism to cope with stressful environments; thus females from different populations may be able either to migrate in favourable areas where they can exploit abundant food resources or remain residents and perform high levels of oosorption to cope with the seasonal shortage of food.

The early developmental environment has a profound influence on an individualâ s life history trajectory and parents have tremendous influence over this environment. Despite the wealth of research demonstrating that incubation temperature affects a suite of traits important to fitness in reptiles, we are only now discovering that nest temperatures are a defining component of the avian developmental environment. Aspects of the nest environment may be an important and overlooked maternal effect in birds as nearly all birds physically incubate their eggs, thus providing a clear link between parental behavior and the developmental environment of the avian embryo. My research used an interdisciplinary approach, uniting concepts from life history theory, bioenergetics. immunology, and physiological ecology to investigate the importance of incubation temperature to avian phenotype. I found that incubation temperature affects a suite of traits important for future development, survival and reproduction in a species of birds. Using a population of wood ducks (Aix sponsa) that has been the subject of long term studies I investigated the effects of incubation temperature on embryonic developmental patterns and energy expenditure, and body size and condition, stress endocrinology, thermoregulatory performance, and immunocompetence in hatchling wood ducks. In all experiments freshly laid wood duck eggs were collected from nest boxes located in SC, transported to Virginia Tech and incubated at one of three temperatures (35.0, 35.9, 37.0Ë C) that fell within the range of naturally-incubated wood duck nest temperatures. I found that less than 1Ë C differences in incubation temperature affected duckling growth and body condition, stress endocrinology, immune responses, and energy expended to thermoregulate. Many of these effects persisted days to weeks after hatching. In most cases, ducklings that hatched from eggs incubated at lowest temperature performed poorer than ducklings that hatched from eggs incubated at the higher temperatures. Incubation temperature also affected wood duck embryonic developmental trajectories and energy expended during incubation with embryos from the low incubation temperature expended more energy and developing slower than ducklings incubated at the higher temperatures. Embryonic energy expenditure could contribute to effects observed on hatchling phenotype. Because I demonstrate that incubation temperature affects hatchling phenotypic quality, the variability upon which natural selection acts, my findings have implications for avian ecology, life history evolution and conservation.
Ph. D.

There is a general consensus among scientists that climate change poses a severe threat to organisms with little tolerance for higher temperatures than those in their current environmental niche. The effects of increased environmental temperature will be of significance in those organisms combining reduced thermal tolerance and limited mobility across the environment to allow shifts to more optimal habitat. The relict populations of the freshwater crayfish genus, Euastacus, in Queensland are generally restricted to cooler mountain-top streams and are at significant extinction risk due to these factors. While noted as threatened by increases in environmental temperature, key knowledge gaps exist regarding the thermal biology of these crayfish. This project sought to answer the underlying question; Are species of Euastacus in Queensland, some with severely restricted distributions, currently experiencing thermal stress in warmer parts of the year? It was anticipated that evidence of fitness reducing temperatures in these crayfish would give an indication of the future effect of climate change, primarily increased temperature, and initiate further research into this vulnerable genus. A minimally-intrusive assessment of physiological and biochemical indicators of tissue damage in response to an imposed thermal stressor were initially developed using a model organism, Cherax quadricarinatus. The data provided “proof of concept” for a validated method to contrast the level of thermal stress experienced between individuals of the same species, conditioned to different temperatures. Additionally, the results indicated that the physiological and biochemical indicators gave some defined effects of higher temperature on the model organism, and opened up the potential for a suite of non invasive assays to be used within the genus Euastacus.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

ABSTRACT A review of annual monitoring reports for stream restoration projects on surface coal mines in the central Appalachian Mountains found that the criteria used for judging the success of the projects was generally based on visual assessments of habitat structure which were evaluated using the Rapid Bioassessment Protocol (RBP) (Palmer and Hondula, 2014). In recent years the Hydrogeomorphic Approach (HGM), which was originally developed to evaluate wetlands, has been adapted for stream evaluations as well (Summers, et al., 2017). Both of these methods are primarily a means to determine if suitable habitat structure and riparian growth are present to support aquatic life. It is assumed that if habitat structure is suitable then macroinvertebrate and other life will be present. However, each of these two methods place emphasis on different aspects of habitat and riparian structure. The primary purpose of this project is to compare and contrast how effective these two methods are at evaluating reconstructed streams on surface coal mines. A secondary objective is to determine if macroinvertebrate assemblages in reconstructed streams is significantly different from that of reference streams not impacted by mining. Research on benthic community structure downstream of coal mining activities suggests that even after many decades taxa richness and abundance still have not recovered from indirect impacts (Petty, et al., 2010). Information on reconstructed streams directly impacted is lacking. This project evaluates streams that were reconstructed five years prior using the RBP and HGM methods, and compares them to local reference streams that have minimal to no mining impacts. Multiple benthic metrics are also used to evaluate community structure. REFERENCES Petty, J. Todd, Jennifer B. Fulton, Michael P. Strager, George T. Merovich Jr., James M. Stiles, and Paul F. Ziemkiewicz. 2010. Lanscape indicators and thresholds of stream ecological impairment in an intensely mined Appalachian watershed. Journal of the North American Benthological Society, 29(4): 1292-1309. Palmer, Margaret A., and Kelly L. Hondula. 2014. Restoration as mitigation: analysis of stream mitigation for coal mining impacts in southern Appalachia. Environmental Science and Technology 48: 10552-10560. Summers, Elizabeth A., Chris V. Noble, Jacob F. berkowitz, and Frank J. Spilker. 2017. Operational Draft Regional Guidebook for the Functional Assessment of High-Gradient Headwater Streams and Low-Gradient Perennial Streams in Appalachia. ERDC/EL TR-17-1.

Orientador: Laurence Marianne Vincianne Culot
Coorientador: Olívia de Mendonça Furtado Pimenta
Coorientador: Renata Gonçalves Ferreira
Banca: Guilherme Gomes
Banca: Patricia Izar
Resumo: O mico-leão-preto (MLP, Leontopithecus chrysopygus) é uma espécie de primata neotropical ameaçada de extinção, sendo que tanto esforços in situ, quanto ex situ devem ser feitos para sua conservação. O entendimento das condições do cativeiro que melhoram o bem-estar dos indivíduos é necessário para viabilizar o sucesso reprodutivo ex situ. No entanto, indivíduos com diferentes perfis comportamentais podem responder de formas distintas a um mesmo estímulo tendo seu bem-estar impactado de diferentes maneiras. O bem-estar animal pode ser avaliado através de variáveis comportamentais (via o estudo de comportamentos potencialmente indicativos de estresse - BPIS) e fisiológicas (via o estudo dos níveis de metabólitos fecais de glicocorticóides - MGFs). Assim, os objetivos desse trabalho foram: 1) determinar o efeito das condições de cativeiro, período do dia e estação do ano sobre o comportamento e sobre os níveis de MGFs; 2) determinar a relação entre os comportamentos e os níveis de MFGs; 3) definir os eixos que compõe o perfil de comportamento gênero-normativo e os eixos que representam as diferentes formas de reação ao estresse entre os BPIS; e 4) identificar os estilos de enfrentamento da população de MLP estudada (via a análise da relação entre os tipos comportamentais, formas de reação ao estresse e índices hormonais de MFGs). Foram observados 11 indivíduos (3 fêmeas e 8 machos) no Centro de Primatologia do Rio de Janeiro durante 15 dias em duas estações (verão e inverno), em... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Black Lion tamarin (BLT, Leontopithecus chrysopygus) is a threatened neotropical primate species for which both in situ and ex situ efforts have to be done for its conservation. The understanding of which captive conditions improve the welfare of individuals is necessary to enable ex situ reproductive success. However, individuals with different behavioral profiles may respond differently to the same stimulus, consequently impacting their welfare in different ways. Animal welfare can be assessed through behavioral (through the study of behaviors potentially indicative of stress - BPIS) and physiological variables (through the study of fecal metabolites of glucocorticoids - MGFs). Therefore, the aims of the study were: 1) to determine the effect of the captive condition, period of the day and season on the behavior and the levels of MGFs; 2) to determine the relationship between behaviors and levels of MFGs; 3) to identify axes that make up the gender-normative behavioral profile (among normative behavioral patterns - GNBs ) and axes of the forms of stress reaction (among BPIS) and; 4) to identify coping styles (through an analysis of the relationship between behavioral types, forms of reaction to stress and hormonal indices of MFGs). We observed 11 individuals (3 females and 8 males) in the Primatology Center of Rio de Janeiro for 15 days in two different seasons (summer and winter) in 4 different treatments: 1 malefemale pair with its adult twins, 1 male-female pair, 1 m... (Complete abstract click electronic access below)
Mestre

Oxidative stress, described as an imbalance between the concentration of reactive oxygen species (ROS) and antioxidants, is one of the most important mechanisms of stressors’ action on plants. On the other hand, similar plants’ response to different stress factors and oxidative stress induced increase in the activity of antioxidative enzymes triggers plants’ adaptation to the particular stressor, as well as cross-adaptation to different stress factors. The aim of the dissertation research is to investigate the impact of different stress factors (ozone, UV-B radiation, drought and heavy metals) on growth and intensity of oxidative stress of spring barley, and to estimate the role of oxidative stress and antioxidative system on plants resistance and cross-adaptation to different stress factors. It was detected, that oxidative stress is the major cause of plant’s growth reduction induced by similar stress factors (heavy metals), whereas the specific impact of stressors is low. When plants are exposed to different stressors (drought, ozone, UV-B radiation, heavy metals Cd and Cu), the impact of their specific action increases, however, oxidative stress remains the major reason of plants’ growth reduction. The increase in antioxidative protection and the reduction in the intensity of oxidative stress is the reason of plant adaptation to the stressors with strong oxidative features (Cu and ozone); whereas cross-adaptation to the stressors with lower oxidative potential (Cd and UV-B... [to full text]
Vienas iš pagrindinių daugumos stresorių neigiamo poveikio augalams mechanizmų yra oksidacinis stresas – disbalansas tarp aktyvių deguonies junginių (ADJ) ir antioksidantų koncentracijos bei aktyvumo pokyčių ląstelėje. Kita vertus, panaši augalų reakcija į skirtingų veiksnių poveikį bei oksidacinio streso sužadintas antioksidacinių fermentų aktyvumo padidėjimas gali lemti augalų prisitaikymą ir padidėjusį jų atsparumą ne tik tam pačiam, bet ir kitiems nepalankiems veiksniams, t. y. kryžminę adaptaciją. Disertacijos tyrimų tikslas – ištirti skirtingų savo prigimtimi streso veiksnių (ozono, UV-B spinduliuotės, sausros ir sunkiųjų metalų) poveikį vasarinių miežių augimui ir oksidacinio streso stiprumui ir įvertinti oksidacinio streso bei antioksidacinės sistemos įtaką augalų atsparumui skirtingų stresorių poveikiui ir kryžminės adaptacijos formavimuisi. Nustatyta, kad skirtingų tos pačios grupės veiksnių (sunkiųjų metalų) sukeltas oksidacinis stresas labiausiai lemia miežių augimo depresiją, o savitasis atskirų veiksnių poveikis yra nežymus. Veikiant skirtingos prigimties aplinkos veiksniams (sausrai, ozonui, UV-B spinduliuotei, sunkiesiems metalams) savitojo jų poveikio įtaka miežių augimui sustiprėja, tačiau oksidacinio streso poveikis vis tiek lieka stipriausias. Antioksidacinės sistemos aktyvumo padidėjimas ir oksidacinio streso susilpnėjimas lemia miežių kryžminę adaptaciją stipriomis oksidacinėmis savybėmis pasižyminčių aplinkos veiksnių poveikiui (variui ir ozonui), o... [toliau žr. visą tekstą]

The biogeographic distribution of organisms is determined by physiological characteristics that enable a population to persist in a specific location. Global climate change effects are anticipated to increase the physiological stress experienced by organisms. Consequently, it is important to understand physiological responses to environmental stress and the mechanisms used by animals to cope with variable conditions. I investigated the physiological response to environmental stress in two species of mussel from New Zealand, Perna canaliculus and Mytilus galloprovincialis, using quantitative PCR and ecological field experiments. A series of laboratory and field experiments were done to manipulate stress levels and the expression levels of three heat shock protein genes (hsp24, hsp70, hsp90) were measured. A transcription regulatory gene (elf2) and a cell cycle regulatory gene (tis11d) were also measured. The dynamics of stress response gene expression in response to acute stress and gene expression changes in the natural population due to varying forms of environmental stress were tested. Between-zone translocations of different sized M. galloprovincialis and P. canaliculus were done at two sites in both east and west regions of the South Island of New Zealand. Site was found to be the most important factor in stress response. Apparent low food and high exposure stress interacted to create the particularly elevated stress response at the Timaru site. The adaptive ability of mussels transplanted between sites with varying environmental conditions was also tested. Results suggest that acclimation may be limited under stressful conditions. Furthermore, I found that P. canaliculus, the predominantly low-zone species, had a lower stress response than M. galloprovincialis, which was contradictory to predictions. The investigations described in this thesis suggest that interactive effects of abiotic stress and food limitations are particularly challenging for animals. With the severity of climate change scenarios predicted, changes in water quality and aerial and seawater temperature suggest mussel populations are likely to be negatively affected in the future. This work also illustrates the great potential to utilise molecular techniques for analysis of physiological processes of non-model organisms in a real-world setting.

Physicochemical factors, algal diversity, taxonomic composition and standing crop were investigated across a broad gradient of AMD stress in streams and rivers. 52 sites were surveyed in the vicinity of Greymouth, Reefton, Westport and Blackball, on the West Coast, South Island. Seven sites in the Reefton area were sampled from April 2006 - February 2007 to establish changes over time in benthic algal communities of AMD and reference streams. Longitudinal change and ecosystem recovery were also investigated by sampling eight sites down Devils Creek, Reefton, and two of its tributaries. AMD has negative impacts on algal diversity, generally increases the dominance of certain taxa and, where metal oxide deposition or hydraulic disturbance are not great, can lead to algal proliferations. These proliferations were chlorophyte dominated, predominantly by filamentous Klebsormidium acidophilum. From the general survey a total of 15 taxa were identified from the most severely impacted sites (pH <3.6), which included both acidophiles and acidotolerant algae. Multivariate analyses strongly suggest that pH was the dominant factor controlling taxonomic occurrence of diatoms, macroalgae and the structure of the total assemblage. Other factors such as conductivity, metal oxide deposition, temperature, depth, month, geographic location and altitude were also important. Algal communities changed over time and this became more marked as AMD impact decreased. This was presumably due to AMD stressors reducing diversity, and thus the available scope for assemblage change. Longitudinal differences in assemblage structure within Devils Creek appeared to be in response to dilution of AMD in upper reaches and to changes in natural physical features such as gradient in mid and lower reaches. After a distance of 7.2 km the physicochemical effects of AMD and suspended clay inputs were minimal. At this site and at several previous sites, the assemblage exhibited a degree of recovery towards that found at unimpacted sites. A range of algae found in the broad scale-survey are potentially useful 'sensitive' indicators. These included: Heteroleibleinia purpurascens; Achnanthes oblongella; Oedogonium sp. and Spirogyra sp. In contrast: Euglena mutabilis; Navicula cincta; K. acidophilum; Microspora quadrata and Microthamnion kuetzingianum may be useful 'tolerance' indicators. These data show that AMD has a range of negative impacts on algae, and algae may be a useful tool for monitoring these impacts in West Coast streams.

Orientador: Eliane Gonçalves de Freitas
Banca: Carla Forte Maiolino Molento
Banca: Elisabeth Criscuolo Urbinati
Resumo: Em ambientes naturais os animais são confrontados com diferentes estressores. Se o estressor é moderado e de curta duração, a resposta às informações ambientais é uma adaptação que permite que o animal responda imediatamente a uma situação ameaçadora. Além disso, manter os animais em ambientes que lhe ofereçam menores condições de estresse, por demandarem um menor gasto energético, pode melhorar sua taxa de crescimento. No entanto, estressores mais intensos podem desencadear um estado patológico conhecido como distresse que pode ser prejudicial a sua fisiologia e comportamento. O ambiente artificial, por sua vez, pode ser desprovido de novos estímulos, provocando monotonia igualmente considerada prejudicial ao animal. Assim, manter os animais sob condições de estressores moderados, que mantenham as características adaptativas ao animal seria uma condição que aumentaria sua prontidão ao desafio social e o seu crescimento. Dessa forma, nosso objetivo foi testar os efeitos do estressor moderado sobre o desafio social e o crescimento em peixes. Para isso 45 machos adultos de tilápia-do-nilo foram isolados e submetidos a três tratamentos: Situação de ambiente monótono (N = 13): ausência de estímulos novos no ambiente; Situação de estressor intenso (N = 12): confinamento; Situação de estressor moderado (N=9): perturbação no ambiente. Foram realizadas filmagens de 5 minutos duas vezes ao dia (9h e 14h) durante a apresentação aos estressores para quantificarmos a taxa de batimento opercular que foi utilizada como indicador de estresse assim como os níveis de cortisol plasmático e a taxa de crescimento específico. Além disso, foi avaliada a resposta do animal ao desafio social representado pelo teste do espelho durante o qual foram realizadas filmagens de 10 minutos. Em relação a taxa de crescimento observamos que situações de estressores moderados aumentaram o crescimento...
Abstract: In natural environments, animals have to deal with numerous and constant challenges, being exposed to different stressors. Once the stressor is mild and of short duration, the answer to this environmental information is an adaptation that allows the animal immediately respond to a threatening situation. Also, keep the animals in environments that offer lower stress conditions you can improve your growth rate. However, more intense and long lasting stressors may trigger to a physiological condition known as distress. Artificial environments, in other hand, can provide a lack of stimuli and cause monotone, also considered to be detrimental to the animal. Keep the animals under mild stressors conditions are, therefore, to maintain adaptive features of the animal, which is a condition that increases the readiness to social challenge and improve individual's welfare. Thus, our aim in this study was to test the effects of mild stressors on the social challenge and welfare in fish. For this, 34 male adults of the fish Nile tilapia were isolated and subjected to three treatments: a) a situation of monotone (N = 13): absence of new stimuli in the environment; b) a situation of intense stress (N = 12): provided by individual containment; and c) a situation of mild stress (N = 9): disturbance in the environment. Video records of five minutes each were filmed twice a day, (9h and 14h) during the presentation of the stressors to the fish, to quantify the ventilatory rate, the plasma cortisol levels and the specific growth rate. We also evaluated the animal's response to the social challenge, provided by a mirror test, recorded during 10 minutes. Regarding the growth rate, we observed that situation of mild stress increased fish growth, whereas monotone and intense stress situations had decreased their growth rate. Agonistic interactions increased in situations of mild stress, remained stable in conditions of intense stress and decreased in...
Mestre