Serviços dos ecossistemas prestados pelos estuários : especiação e capacidade de retenção do fósforo

O fator nutricional presente nos sapais não é só importante para os organismos que nele habitam como também apresenta uma importância ecológica a uma maior escala. Exemplifica-se este fato com a capacidade de retenção do Fósforo (P) por parte das plantas podendo estas competir como produto químicos para sua imobilização através da incorporação da sua fração biodisponível para cumprimento dos mecanismos básicos de sobrevivência. O rizosedimento dessas plantas é uma importante fonte de nutrientes necessários para garantia básica da perpetuação de todos os serviços (regulação, provisão, cultural) gerados pelo ambiente. A perda de áreas de sapal foi o motivo principal para a elaboração desta tese visto a preocupação em relação aos impactes que a perda de serviços associados à área de estudo escolhida, o sistema lagunar da Ria de Aveiro, poderá vir sofrer caso aconteçam alterações hídricas (naturais ou antrópicas) mais acentuadas no futuro. Essa tese assume como compromisso chamar a atenção para essa questão como também investigar os mecanismos do ciclo do P este importante nutriente considerado essencial para a manutenção da vida em nosso planeta. Para este estudo foram escolhidas 3 espécies de plantas halófitas representantes do sapal amostral, são elas: Bolbochenous maritimus, Spartina maritima e de Juncus maritimus. As questões levantadas buscam compreender o papel do P nas transformações que ocorrem no rizosedimento das halófitas em 3 diferentes contextos: (i) quando comparados os valores da biomassa de P associado às halófitas estudadas (estudo realizado nos sapais povoados por Spartina maritima e Juncus maritimus) em toda extensão da Ria de Aveiro (ii) quando da disponibilidade de P perante a presença de poluentes inorgânicos no Largo do Laranjo, que corresponde a uma zona historicamente contaminada por metais (estudo realizado no rizosedimento das espécies Bolbochenous maritimus e Juncus maritimus) e (iii) quanto à intrusão superficial da água salgada da laguna (estudo focado na avaliação da perda do P próximo às raízes das halófitas que habitam a zona externa do dique do Baixo Vouga Lagunar (BVL) que corresponde à zona de confluência do Rio Vouga com a Ria de Aveiro). Por meio da análise do rizosedimento e da biomassa das diferentes halófitas predominantes do sapal foi possível verificar que, em relação à carga nutritiva fosfática, de Norte (Canal de São Jacinto/Ovar) a Sul (Canal de Mira) da Ria de Aveiro, a cota do sapal é mais importante do que a natureza espacial do sistema. Esta informação é primordial para a assertividade de futuras medidas de criação e reabilitação das áreas de sapal na Ria de Aveiro. Os estudos realizados nas áreas impactadas (Largo do Laranjo e BVL) incidiram na análise do perfil vertical rizosedimentar das halófitas pertencentes ao sapal médio-alto. Estes estudos revelaram que o rizosedimento dessas halófitas possui características peculiares que definem a dinâmica do ciclo do P de forma bastante característica. O rizosedimento das halófitas presentes no Largo do Laranjo apresentaram teores biodisponíveis de P equivalentes àqueles presentes no rizosedimento de área mais afastada da fonte pontual de contaminação para as mesmas espécies. Numa visão otimista, os resultados revelam que ambos sapais, Largo de Laranjo e Cais do Bico, apresentam condições equiparável para perpetuação dos serviços por eles gerados, que nesse caso se tornam ainda mais valiosos devido a garantia da fitoestabilização dos contaminantes (prevenção da entrada de contaminantes na coluna d’água e na cadeia alimentar). No Baixo Vouga Lagunar a análise espacial do sapal na zona exterior ao dique revelou a perda da diversidade das espécies bem como o aumento da área de vasa e consequentemente a perda dos teores de P associados ao rizosedimento das halófitas mais expostas aos efeitos da compressão costeira intensificados pelas ações naturais e antrópicas a que a Ria está sujeita. Em geral, a degradação dessa área de sapal devido aos fenômenos de assoreamento ou de erosão não pode ser separada dos processos sedimentares na área envolvente, principalmente no caso da Ria de Aveiro que tem sofrido constantes mudanças para atender às necessidades das atividades humanas. Essa tendência provavelmente não mudará no futuro próximo. Consequentemente, a evolução da laguna será principalmente dependente do resultado direto das ações humanas que deverão sempre encontrar formas de compensar os danos causados no âmbito de intervenções de reabilitação do sistema hídrico. A recriação de áreas de sapal pode ter lugar como medida mitigadora no âmbito de intervenções de reabilitação de áreas degradadas e ainda poderá servir como forma de captura de P para programas de utilização de fertilizantes naturais (componente desejável para a agricultura moderna o que é particularmente importante para as regiões altamente dependentes do mercado de importação). Deste modo, recomenda-se que a recuperação das áreas de sapal seja enquadrada no âmbito de intervenções mais amplas de valorização dos sistemas estuarinos e lagunares.

Caracterização geoquímica dos ecossistemas na zona de protecção às Fontes das Cinco Bicas e da Saúde

O concelho de Pombal possui uma elevada riqueza em Recursos Naturais, nomeadamente em Recursos Minerais e Nascentes Naturais. De entre as Nascentes Naturais existentes neste concelho, as Fontes das Cinco Bicas e da Saúde, têm sido privilegiadas, devido à qualidade bacteriológica e química das suas águas e à sua localização geográfica (zona ainda não abastecida com água da rede pública), sendo alvo de estudos e de um vasto trabalho, por parte do Município, de onde surgiu a delimitação de uma Zona de Protecção, de importância relevante para a população concelhia. A Zona de Protecção às Fontes das Cinco Bicas e da Saúde, abrange três zonas, sendo elas designadas por próxima, intermédia e alargada. Este estudo, tem como objectivo fundamental, a caracterização geoquímica e ambiental, de uma área de 8 Km2, envolvendo a zona delimitada como “Zona de Protecção às Fontes das Cinco Bicas e da Saúde”, utilizando os solos e a água como meios amostrais. A área de trabalho abrange também parte da Área declarada de Reserva (Área de Reserva – A), para efeitos de aproveitamento de Argilas Especiais (Decreto – Regulamentar n.º 35/95, de 22 de Novembro), e toda ela está inserida na área declarada Cativa, para efeitos de exploração de Argilas (Portaria n.º 448/90 de 16 de Junho), pelo que existem vários núcleos de actividade extractiva em laboração. Este trabalho vai permitir caracterizar ambientalmente a área de estudo, a água das nascentes em causa, bem como analisar a possível interferência das unidades industriais e agrícolas nas Fontes das Cinco Bicas e da Saúde.

Environmental impacts of freshwater use and suspended solids in life cycle assessment

Perturbation of natural ecosystems, namely by increasing freshwater use and its degradative use, as well as topsoil erosion by water of land-use production systems, have been emerging as topics of high environmental concern. Freshwater use has become a focus of attention in the last few years for all stakeholders involved in the production of goods, mainly agro-industrial and forest-based products, which are freshwater-intensive consumers, requiring large inputs of green and blue water. This thesis presents a global review on the available Water Footprint Assessment and Life Cycle Assessment (LCA)-based methods for measuring and assessing the environmental relevance of freshwater resources use, based on a life cycle perspective. Using some of the available midpoint LCA-based methods, the freshwater use-related impacts of a Portuguese wine (white ‘vinho verde’) were assessed. However, the relevance of environmental green water has been neglected because of the absence of a comprehensive impact assessment method associated with green water flows. To overcome this constraint, this thesis helps to improve and enhance the LCA-based methods by providing a midpoint and spatially explicit Life Cycle Impact Assessment (LCIA) method for assessing impacts on terrestrial green water flow and addressing reductions in surface blue water production caused by reductions in surface runoff due to land-use production systems. The applicability of the proposed method is illustrated by a case study on Eucalyptus globulus conducted in Portugal, as the growth of short rotation forestry is largely dependent on local precipitation. Topsoil erosion by water has been characterised as one of the most upsetting problems for rivers. Because of this, this thesis also focuses on the ecosystem impacts caused by suspended solids (SS) from topsoil erosion that reach freshwater systems. A framework to conduct a spatially distributed SS delivery to freshwater streams and a fate and effect LCIA method to derive site-specific characterisation factors (CFs) for endpoint damage on aquatic ecosystem diversity, namely on algae, macrophyte, and macroinvertebrates organisms, were developed. The applicability of this framework, combined with the derived site-specific CFs, is shown by conducting a case study on E. globulus stands located in Portugal as an example of a land use based system. A spatially explicit LCA assessment was shown to be necessary, since the impacts associated with both green water flows and SS vary greatly as a function of spatial location.

Ecology and physical condition of red deer in the Iberian Peninsula: implications for management

The red deer (Cervus elaphus) is currently one of the most widespread and abundant wild ungulates in the Iberian Peninsula and is extremely important both ecologically, as a key species for the functioning of the ecosystems, and economically, as a major game species. In Iberia, red deer populations are subjected to different management systems that may affect the physical condition of the individuals, with further consequences for population dynamics. Studies investigating the effects of management practices and environmental conditions on the performance of red deer are still rare regarding Mediterranean ecosystems. Much of the knowledge concerning the ecology of red deer and the impact of management on its physical condition is based on studies conducted in northern and central regions of Europe, where climatological features and management practices differ from those observed in the Mediterranean areas of Iberia. Studies on a biogeographical scale can provide important insights into the relationships between species and a particular environment and contribute to the development of more targeted and appropriate management practices. The optimisation of sampling procedures and the fine-tuning of pre-existing analytical techniques are also fundamental to a more cost-effective monitoring and, therefore, are of enormous value to wildlife managers. In this context, the main aims of this thesis were: 1) to optimise the procedures used to assess the physical condition of red deer; and 2) to identify relevant management and environmental factors affecting the nutritional condition and stress physiology of red deer in the Mediterranean ecosystems of Iberia, as well as any potential interactions between those factors. Two studies with a methodological focus, presented in the first part of the thesis, demonstrated that the physical condition of red deer can be evaluated more simply, using more cost- and time-effective procedures than those traditionally used: i) it was shown that only one kidney and its associated fat is enough to assess nutritional condition in red deer; and ii) the feasibility of using near infrared spectroscopy to predict the concentrations of stress hormone metabolites was demonstrated using faeces of red deer for the first time. Subsequently, two large-scale observational studies, conducted in representative red deer populations found in Mediterranean Iberia, highlighted the importance of considering seasonal environmental variations and variables related to hunting management practices to better understand the nutritional and physiological ecology of red deer. High population densities had adverse effects on the nutritional condition of the deer and were associated with increased stress levels in natural populations without supplementary feeding. Massive hunting events involving the use of hounds were also identified as a potential source of chronic stress in red deer. The research presented in this thesis has clear implications regarding the management and monitoring of red deer populations in Mediterranean environments and is intended to help wildlife managers to implement more effective monitoring programmes and sustainable management practices.

Early post-fledgling survival in a fragmented population of a tropical cooperative breeding passerine

During the last years tropical forest has been a target of intense study especially due to its recent big scale destruction. Although a lot still needs to be explored, we start realizing how negative can the impact of our actions be for the ecosystem. Subsequently, the living community have been developing strategies to overcome this problem avoiding bottlenecks or even extinctions. Cooperative breeding (CB) has been recently pointed out as one of those strategies. CB is a breeding system where more than two individuals raise one brood. In most of the cases, extra individuals are offspring that delay their dispersal and independent breeding what allows them to help their parents raising their siblings in the subsequent breeding season. Such behavior is believed to be due, per example, to the lack of mates or breeding territories (ecological constraints hypothesis), a consequence of habitat fragmentation and/or disturbance. From this point, CB is easily promoted by a higher reproductive success of group vs pairs or single individuals. Accordingly, during this thesis I explore the early post-fledging survival of a cooperative breeding passerine, namely the impact of individual/habitat quality in its survival probability during the dependence period of the chicks. Our study species is the Cabanis’s greenbul (Phyllastrephus cabanisi), a medium-sized, brownish passerine, classified within the Pycnonotidae family. It is found over part of Central Africa in countries such as Angola, Democratic Republic of the Congo, Mozambique and Kenya, inhabiting primary and secondary forests, as well as woodland of various types up to 2700m of altitude. Previous studies have concluded that PC is a facultative cooperative breeder. This study was conducted in Taita Hills (TH) at the Eastern Arc Mountains (EAM), a chain of mountains running from Southeast Kenya to the South of Tanzania. TH comprises an area of 430 ha and has been suffering intense deforestation reflecting 98% forest reduction over the last 200 years. Nowadays its forest is divided in fragments and our study was based in 5of those fragments. We access the post-fledging survival through radio-telemetry. The juvenile survey was done through the breeding females in which transmitters were placed with a leg-loop technique. Ptilochronology is consider to be the study of feather growth bars and has been used to study the nutritional state of a bird. This technique considers that the feather growth rate is positively proportional to the individual capability of ingesting food and to the food availability. This technique is therefore used to infer for individual/habitat quality. Survival was lowest during the first 5 days post-fledging representing 53.3%. During the next 15 days, risk of predation decreased with only 14.3% more deceased individuals. This represents a total of only 33% survived individuals in the end of the 50 days. Our results showed yet a significant positive relationship between flock size and post-fledging survival as well as between ptilochronology values and post-fledgling survival. In practice, these imply that on this population, as bigger the flock, as greater the post fledging survival and that good habitat quality or good BF quality, will lead to a higher juvenile survival rate. We believe that CB is therefore an adaptive behaviour to the lack of mates/breeding territory originated from the mass forest destruction and disturbance. Such results confirms the critical importance of habitat quality in the post-fledging survival and, for the first time, demonstrates how flock size influences the living probability of the juveniles and therefore how it impacts the (local) population dynamics of this species. In my opinion, future research should be focus in disentangle individual and habitat quality from each other and verify which relationship exist between them. Such study will allow us to understand which factor has a stronger influence in the post-fledging survival and therefore redirect our studies in that direction. In order to confirm the negative impact of human disturbance and forest fragmentation, it would be of major relevance to compare the reproductive strategies and reproductive success of populations living in intact forests and disturbed patches.

Impact of natural and/or chemical stressors on the freeze-tolerant and euryhaline enchytraeid, Enchytraeus albidus

Rapid climatic changes are taking place in Arctic, subarctic and cold temperate regions, where predictions point to an increase in freeze-thaw events, changes in precipitation, evaporation and salinity patterns. Climate change may therefore result in large impacts in ecosystem functioning and dynamics, especially in the presence of contaminants due to intense anthropogenic activities. Even though multiple stress approaches have received increasing interest in the last decades, the number of such studies is limited. In particular, knowledge on the effect of freezethaw events and salinity fluctuations on ecotoxicology of soil invertebrates is lacking, especially important when considering supralittoral species. Therefore, the aim of this thesis was to investigate the effects of low temperature and salinity fluctuations, singly and in combination with contaminants, in the freeze-tolerant and euryhaline enchytraeid Enchytraeus albidus. The assessment of population level endpoints (survival and reproduction), along with physiological and biochemical parameters such as levels of cryoprotectants, ice/water content, oxidative stress biomarkers, cellular energy allocation, and tissue concentration of chemicals (when applied), provided new and valuable knowledge on the effects of selected physical and chemical stressors in E. albidus, and allowed the understanding of adjustments in the primary response mechanisms that enable worms to maintain homeostasis and survival in harsh environments such as polar and temperate-cold regions. The presence of moderate levels of salinity significantly increased freeze-tolerance (mainly evaluated as survival, cryoprotection and ice fraction) and reproduction of E. albidus. Moreover, it contributed to the readjustments of cryoprotectant levels, restoration of antioxidant levels and changed singnificantly the effect and uptake of chemicals (copper cadmium, carbendazim and 4-nonylphenol). Temperature fluctuations (simulated as daily freeze-thaw cycles, between -2ºC and -4ºC) caused substancial negative effect on survival of worms previsouly exposed to non-lethal concentrations of 4-nonylphenol, as compared with constant freezing (-4ºC) and control temperature (2ºC). The decrease in cryoprotectants, increase in energy consumption and the highest concentration of 4-nonylphenol in the tissues have highlighted the high energy requirements and level of toxicity experienced by worms exposed to the combined effect of contaminants and freezing-thawing events. The findings reported on this thesis demonstrate that natural (physical) and chemical stressors, singly or in combination, may alter the dynamics of E. albidus, affecting not only their survival and reproduction (and consequent presence/distribution) but also their physiological and biochemical adaptations. These alterations may lead to severe consequences for the functioning of the ecosystems along the Arctic, subarctic and cold temperate regions, where they play an important role for decomposition of dead organic matter. This thesis provides a scientific basis for improving the setting of safety factors for natural soil ecosystems, and to underline the integration of similar investigations in ecotoxicology, and eventually in risk assessment of contaminants.