This study investigates the influence of limnological parameters that are known to influence rotifer species richness and composition in temperate areas on two families of monogonont rotifers in a tropical area. We analysed species richness and diversity of the two families from 133 samples taken from several habitat types in Thailand. Coordinates, elevation, pH, temperature, conductivity, salinity and dissolved oxygen were measured and their effect on rotifers assessed. A total of 60 species in 5 genera was recorded from the two families. Latitude and temperature had an effect on species richness of Brachionidae. None of the variables affected species richness of Lecanidae, except habitat type, albeit not significantly. Habitat type and conductivity had an effect on species composition of the two families, whereas latitude had an effect only on species composition of Lecanidae. Species richness and composition of the two rotifer families are well documented in Thailand and no or only few additional species are expected. The limnological correlates of rotifer diversity seem to be in part comparable to and in part different from those known from temperate areas, suggesting that there may be general trends in rotifer species richness and composition across different latitudes.
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RBINS Staff Publications 2017
Despite the meanwhile well-developed evidence of global Holocene climate fluctuations and the correlation of such events with the transition of cultural periods it remains difficult to estimate regional environmental effects of these climate fluctuations and their impact on human populations. The complexity of ancient societies, our lack of knowledge on their perception of possible environmental problems, and its interrelation with human decision-making, challenges archaeological interpretation of a climatic impact on past societies. Stable carbon isotope data in ancient cereal grains from northern Mesopotamian sites indicate climatic fluctuation throughout the Early Bronze Age, with an abrupt increase in aridity towards the end of the Early Bronze Age, which is supported by oxygen isotopes in biogenic Lithospermae carbonate. These changes have been linked to climatic fluctuations, which are widely considered global, such as Bond Event 3 or the 4.200 cal BP event. In our study we aim to consider how far global climatic fluctuations may have affected agriculture in the Early to Middle Bronze Age Troad. We combine stable carbon and nitrogen isotope data from Troy with archaeobotanical data to consider changes in water and nutrient availability for the Early Bronze Age crops. We further consider anthracological data to reconstruct the Early Bronze Age woodland vegetation, to refine observable changes in stable isotope composition and in the crop assemblages. The results show a continuous reduction in oak and pine throughout Troy I to IV in favour for maquis components. There is indication that woodland exhaust may have started during Troy III with a consecutive use of open and alluvial habitats. The seed remains indicate a certain diversification in crop production in Troy IV with an inclusion of coastal habitats into land use, which may have been a consequence of increased aridity, a changing landscape, and erosion processes on the plateaus that must have already started at the end of Troy II. Stable carbon isotopes in barley, which indicate increased water stress in Troy IV grains add an additional support to the necessity of agricultural change starting in Troy III with the shift of fields into alluvial and in Troy IV to coastal habitats. Our data also correlate with the 4.200 BP event, and the general assumption of an increased aridity, but do rather support all-embracing reformation as an expression of human resilience than the common idea of societal collapse.
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RBINS Staff Publications 2016
