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Skulls of 1,901 harbor seals from the North Sea were systematically investigated for dental, periodontal and cranial disorders as well as pathological changes of the temporomandibular joint (TMJ). Volumetric bone mineral density (vBMD) and microarchitecture of the mandible of a subsample of these specimens were analyzed in respect to age-related changes.
Age at death of examined seals ranged from 1 week to 25 years. Most of the specimens were collected in 1988, when the population suffered from a phocine distemper virus epizootic. Therefore, it is assumed that, contrary to other museum collections, only little overrepresentation of pathological skeletal condition is present in the analyzed death sample.
Age- and sex-related differences in the frequency and severity of pathological changes were observed in the dentition and the TMJ.
Intravital tooth loss, tooth fracture and periapical lesions were recorded more frequently in male seals than in femals. Lesions consistent with temporomandibular joint osteoarthritis (TMJ-OA) also occurred more frequently in males, while lesion severity tended to be higher in female specimens. Severity of TMJ-OA lesions was positively correlated with age.
Significant age-related changes in vBMD and several microarchitectural parameters were observed between individuals of the age classes “young juveniles” (0.5–10 months),“yearlings” (12–23 months),and “adults” (12–25 years),indicating an overall increase in cortical and trabecular area, cortical thickness as well as vBMD with age.
For juvenile animals (≤ 23 months), positive correlations with age were observed for cortical area and thickness, trabecular separation, as well as vBMD. Negative correlations with age existed for trabecular number and thickness as well as for trabecular bone volume fraction (BV/TV) in the juveniles. The findings suggest a reduction in BV/TV with age,due to the bone trabeculae becoming thinner,less numerous and more widely spaced. This detailed knowledge of age-related changes in the structure and mineralization of bones is an important prerequisite for interpreting osseous changes in wild mammals caused by external factors, as such as exposure to environmental contaminants.
The examination of large skeletal collections enables the observation also of rare pathological conditions. In the present investigation a case of anodontia,diagnosed as a manifestation of hypohidrotic ectodermal dysplasia was for the first time described in the harbor seal.
In five juvenile Baltic grey seals,severe osteomyelitis of the jaws was described for the first time. The condition was attributed to disturbed dentin formation,presumably of genetic causation, in the affected individuals.
The present study highlights the fact that systematic analyses of museum collections can provide important insights into the dental and skeletal pathology of wild mammals. These data can be used for reconstructing the health situation and living condition of past animal population.
Tropical wetlands maintain a high biodiversity and provide ecological services which are basis for millions of livelihoods. However, freshwater ecosystems are largely neglected in research and environmental policy. Today they are among the most threatened habitat types throughout the world with highest loss rates for natural inland wetlands in the tropics. The high dependency of local communities upon natural resources makes conservation management for wetlands in developing countries to a particular challenge.
This study investigated the different perspectives of conservation planning at Lake Alaotra, the largest wetland complex of Madagascar. First, the ecological state of Lake Alaotra was assessed to close knowledge gaps and to provide an adequate basis for ecosystem-based conservation measures. Second, I evaluated the community-led management of a small protected area in order to determine its potentials and weaknesses. Third, the local fishery, as the largest lake resource user group, was investigated to understand the drivers of overfishing.
By interlinking the results of the three perspectives of conservation planning – ecology, management and resource user – interrelations and trade-offs between the three dimensions were identified. The current ecological state of Lake Alaotra reveals that the anthropogenic disturbance is favoring the proliferation of invasive plant species and leading to the alteration of the water quality (e. g. hypoxia). Insights into the local management show that the community-based management contributes to the conservation of the natural flora and fauna. However, the small-scale conservation area suffers from isolation and illegal activities, while its management lacks recognition at community level. The fishery sector has grown dramatically although fish catches have fallen sharply. Species composition changes and low reproduction rates are reflecting the fishing pressure. A high population growth and lacking agricultural land force people to enter fishery and increases the human pressure on the lake.
Overall this study shows that the conservation of multiple-value ecosystems, such as tropical wetlands in developing countries, require site-specific multidimensional approaches that interlink ecological demands, resource user needs and the local sociocultural setting. This research demonstrates that: ongoing livelihood dynamics linked to the socio-economic conditions have to be considered to create more realistic management policies; strengthening resource users’ assets will help to decrease the human pressure on the already considerably altered ecosystem; capacity building for local management associations and the adoption of local ideas and management concepts is needed to enable the evolvement of an locally legitimated and tailored wetland conservation management.
Die Dissertation behandelt Aussagemöglichkeiten der mikroskopischen (Lichtmikroskopie und Rasterelektronenmikroskopie) Untersuchung am Leichenbrand. Die Hauptziele der Untersuchung sind eine Präzisierung der Bestimmung des biologischen Lebensalters des Individuums sowie die Feststellung möglicher Veränderungen durch pathologische Prozesse und ihre Unterscheidung von verbrennungsbedingte Artefakte. Verglichen wurden unterschiedliche prähistorische Leichenbrände aus verschiedenen Regionen (Osttürkei, Deutschland, Tschechien, Slowakei), von der mesopotamischen Bronzezeit über die vorrömische Eisenzeit bis in die römische Kaiserzeit. Als Vergleichsmaterial diente eine rezente Population mit bekanntem Sterbealter.
Die durchgeführten histologischen Untersuchungen von Zähnen mit Schmelzhypoplasien haben gezeigt, dass es möglich ist, Aussagen über die Intensität und die Dauer von Episoden von systemischem Stress zu treffen, die Auswirkungen auf die Amelogenese hatten. Basierend auf den aktuellen Vorstellungen über den Ablauf der Amelogenese und die Zusammenhänge zwischen Morphologie und Funktion sekretorischer Ameloblasten kann, durch die Analyse von Veränderungen der normalen Schmelzstruktur, das Reaktionsmuster der sekretorischen Ameloblasten rekonstruiert werden. Die erhobenen Befunde lassen sich mit einem Schwellenwertmodell beschreiben, das drei Stufen der Einschränkung der sekretorischen Ameloblastentätigkeit umfasst.
