Browsing by Author "Sroczynska, Katarzyna Krystyna"
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- Biological variation in temporary streams: understanding river patches at different scales for monitoring and management applicationsPublication . Sroczynska, Katarzyna Krystyna; Chícharo, Luís; Wojtal-Frankiewicz, AdrianaBiota and ecological processes are highly complex and vary at every scale. This underscores the importance of employing a multi-scale design to adequately understand these processes and complex relationships in riverine ecosystems. In addition, there is a strong need to develop appropriately scaled indicators of river ecosystem health that include this biotic complexity in a manageable fashion. Unfortunately, currently available indicators are either too complex or do not adequately capture the highly variable changes to the ecosystem. Patches are good templates for various ecological processes and because they are considered to be stable over the spatial and temporal scales, they can be used as functional filters of important processes in streams. The aim of this thesis is to employ patch theory and multi-scale approach to develop structural and functional indicators of the ecosystem health at the patch level and evaluate in which of the scales these indicators are of the highest relevance for the patch. The system at which these indicators were tested consists of headwater intermittent streams within a Mediterranean catchment. Three scales were considered: reach scale, stream scale and catchment scale. According to the results patch as a source of variation was not well explained by the structural measures of benthic communities at catchment scale. This was related to the effect of occurrence of a strong environmental filter (mainly altitude and its association with conductivity and temperature), which limited distribution of biota and constrained the occurrences of certain species at the smaller scales. Also, these filters were demonstrated to act indirectly through patterns in habitat formation and availability. Patch investigated at the reach scale provided slightly more predictable unit of species organization, nonetheless, still benthic communities of some of the patch types overlapped. Instead, the most consistent measures of ecosystem health that could be applied to studying patches were the metabolism measurements at the reach scale and the isotopic signatures at the stream scale. Next step forward would be to establish reference values for these two approaches for undisturbed systems, and subsequently to incorporate these measures into biomonitoring guidelines. Following disturbance, patches have been shown to be the most appropriate unit used when evaluating biotic recovery. As such, this study represents an important step towards development of better biomonitoring tools as well as evaluation of the restoration effort.
- Influence of mangrove oyster on seston removal: example from Espirito Santo, BrazilPublication . Sroczynska, Katarzyna Krystyna; Chicharo, Luís; Barroso, GilbertoO constante crescimento da população humana aumenta a poluição, nomeadamente nos ecossistemas aquáticos, resultando sobretudo na eutrofização costeira. Contudo, a função de filtradores pode compensar a estimulação fitoplâncton por excesso de nutrientes reduzindo os sintomas primários de eutrofização. No presente estudo, a capacidade herbívora do C. rhizophorae em partículas em suspensão no seu ambiente natural foi determinada utilizando o método in situ de biodeposição e armadilhas de sedimentos especialmente concebidas no âmbito deste projeto. Adicionalmente, o efeito do tamanho corporal na eficácia da taxa de depuração foi também examinada. O trabalho experimental foi levado a cabo no sistema estuarino Piraquê-mirim, (Aracruz, ES, Brasil) durante a segunda semana de Junho de 2012. Os parâmetros ambientais foram medidos em simultâneo com a análise de matéria total particulada (MTP) e Chl a, no início e fim da experiência. A taxa de depuração (TD) foi de 17,99 l.h-1 g -1 DW, uma das mais altas reportadas na literatura, o que poderá estar associado com a elevada concentração de detritos e as diferentes estratégias de alimentação de bivalves residentes em ambientes tropicais. Elevada TD a níveis elevados de matéria orgânica particulada (MOP) suporta a hipótese de que os bivalves podem apresentar alguma flexibilidade na TD de acordo com a qualidade do alimento disponível. A capacidade superior das ostras de mangal para filtrar seston natural, constitui um argumento importante para a proteção e restauração da população natural destas ostras.