Description: Tropical coastal benthic communities will change in species composition and relative dominance due to global (e.g., increasing water temperature) and local (e.g., increasing terrestrial influence due to land-based activity) stressors. This study aimed to gain insight into possible trajectories of coastal benthic assemblages in Raja Ampat, Indonesia, by studying coral reefs at varying distances from human activities and marine lakes with high turbidity in three temperature categories (〈31 °C, 31–32 °C, and 〉32 °C). The benthic community diversity and relative coverage of major benthic groups were quantified via replicate photo transects. The composition of benthic assemblages varied significantly among the reef and marine lake habitats. The marine lakes 〈31 °C contained hard coral, crustose coralline algae (CCA), and turf algae with coverages similar to those found in the coral reefs (17.4–18.8% hard coral, 3.5–26.3% CCA, and 15–15.5% turf algae, respectively), while the higher temperature marine lakes (31–32 °C and 〉32 °C) did not harbor hard coral or CCA. Benthic composition in the reefs was significantly influenced by geographic distance among sites but not by human activity or depth. Benthic composition in the marine lakes appeared to be structured by temperature, salinity, and degree of connection to the adjacent sea. Our results suggest that beyond a certain temperature (〉31 °C), benthic communities shift away from coral dominance, but new outcomes of assemblages can be highly distinct, with a possible varied dominance of macroalgae, benthic cyanobacterial mats, or filter feeders such as bivalves and tubeworms. This study illustrates the possible use of marine lake model systems to gain insight into shifts in the benthic community structure of tropical coastal ecosystems if hard corals are no longer dominant.

Description: The evolution of the Pontocaspian lakes and seas (Caspian Sea, Black Sea, Aral Sea) is characterised by major changes in water levels, which developed into a pulsating system of connected and isolated basins. During the late Quaternary (Late Pleistocene and Holocene), these basins have hosted a unique endemic biodiversity that experienced species turnover events. There are indications that the Pontocaspian species diversity is now in demise because of anthropogenic modifications of the ecosystem, such as habitat alteration, poaching, pollution and invasive species. Little data is available on faunal changes and resilience of Pontocaspian species to help discerning the effect of natural drivers and anthropogenic drivers on the endemic fauna, which is of direct relevance for conservation strategies. \nThis thesis aims to characterize species richness and abundance of fossil faunas to establish a baseline for comparison with the changing biodiversity of today. Mollusc species are used as the study group as they easily fossilize and are abundant in the geological record. They inform us about the composition of communities and how they change, and enable us to reconstruct environments (\xe2\x80\x98habitats\xe2\x80\x99). This is necessary in order to compare biodiversity through different time intervals and establish whether comparable habitats existed as those of today. A baseline of Pontocaspian mollusc faunas was achieved by analysing snapshots from the Caspian Sea basin and the Black Sea basin. Caspian mollusc assemblages are analysed from late Pleistocene (corresponding to the late Khazarian, Hyrcanian, early Khvalynian and late Khvalynian regional stages) and pre-20th century Holocene (Novocaspian) assemblages. Black Sea assemblages from the late Neoeuxinian and late Holocene are described. They are both compared with modern day assemblages. \nThis study shows clear indications of a Pontocaspian mollusc diversity crisis. Overall, in the 20th\xe2\x80\x9321st century, Pontocaspian molluscs have experienced a severe decline in species richness and abundance: a strong turnover towards invasive species in the Caspian basin, a strong habitat decline in parts of the Black Sea basin and a total obliteration in the Aral basin. The late Quaternary mollusc fauna snapshots demonstrate that endemic species dominated the Caspian communities with minor contributions of native species until the late Holocene. The Pontocaspian mollusc species richness in the Caspian Sea basin is higher than in the Pontocaspian habitats of the Black Sea basin, or the Aral Sea basin. Throughout the Late Quaternary, the strong natural fluctuations of Caspian Sea level affected shallow water bivalve species of the genus Didacna, but barely changed the overall composition of the mollusc faunas. Late Quaternary mollusc fauna snapshots of the Black Sea basin show very little change in the Pontocaspian species community since humans impacted the habitats. However, the Black Sea Pontocaspian mollusc communities are currently under severe threat of habitat deterioration and destruction. \nThis research indicates that the Caspian Sea could act as a source for Pontocaspian biota, hence conservation efforts are imperative there. The deeper parts (〉50 m water depth) possibly present a (partial) refuge, and urgent research is required to assess these habitats and their faunas. Future research should focus on improving the taxonomic framework to elucidate the identity of some Pontocaspian cryptic and sister species. We need more distribution and ecological data of current Pontocaspian species and more detailed biodiversity time series coupled with detailed environmental proxies to assess the nature of the Pontocaspian biodiversity crisis more comprehensively and plan conservation actions accordingly.

Description: The accurate assessment of selected soil constituents can provide valuable indicators to identify and monitor land changes coupled with degradation which are frequent phenomena in semiarid regions. Two approaches for the quantification of soil organic carbon, iron oxides, and clay content based on field and laboratory spectroscopy of natural surfaces are tested. (1) A physical approach which is based on spectral absorption feature analysis is applied. For every soil constituent, a set of diagnostic spectral features is selected and linked with chemical reference data by multiple linear regression (MLR) techniques. (2) Partial least squares regression (PLS) as an exclusively statistical multivariate method is applied for comparison. Regression models are developed based on extensive ground reference data of 163 sampled sites collected in the Thicket Biome, South Africa, where land changes are observed due to intensive overgrazing. The approaches are assessed upon their prediction performance and significance in regard to a future quantification of soil constituents over large areas using imaging spectroscopy.

Description: The climate change debate has increased the need for knowledge on both long- and short-term regional environmental changes. In general, these changes may often be a product of multiple causes, which complicates the separation of single driving forces. In this review we focus on current water budget changes in Germany’s capital region, Berlin-Brandenburg, over the last 30 years. Available studies from a variety of disciplines (e.g. hydrology, water engineering, landscape ecology, nature conservation) were analysed in order to (1) identify both local and regional hydrological changes, (2) reveal their potential causes, and (3) discuss responses of ecosystems and society. These studies show that the Berlin-Brandenburg region is widely characterised by decreasing groundwater recharge, leading to decreasing groundwater and lake levels as well as decreasing fluvial discharge. These trends result both from complex, regional human impacts (e.g. long-term effects of hydro-melioration and changes in forest composition) and more general climate warming. The observed and assumed (future) changes of the regional water balance have been creating, and will continue to create, multifaceted impacts on existing ecosystems and society (e.g. wetland drying, decrease of biodiversity, decrease of productivity of grasslands and forests, increasing conflicts of interests). Several efforts to respond to the regional water deficit problem have already been undertaken, comprising for instance land-use optimisation, wetland restoration measures and the reestablishment of mixed deciduous forests. In general, however, the reviewed regional material on this topic reveals that the number and complexity of empirical studies are still poor. Thus, for both the identification and the explanation of current water balance changes and their effects, as well as for development and implementation of adaptive strategies, further multidisciplinary research efforts at different scales, including interregional comparisons, are required. Furthermore, both the observation of hydrological changes and the evaluation of adaptive and mitigative responses require at least continuous or, even better, extended monitoring efforts.

Description: Information on soil clay and organic carbon content on a regional to local scale is vital for a multitude of reasons such as soil conservation, precision agriculture, and possibly also in the context of global environmental change. The objective of this study was to evaluate the potential of multi-annual hyperspectral images acquired with the HyMap sensor (450–2480 nm) during three flight campaigns in 2004, 2005, and 2008 for the prediction of clay and organic carbon content on croplands by means of partial least squares regression (PLSR). Supplementary, laboratory reflectance measurements were acquired under standardized conditions. Laboratory spectroscopy yielded prediction errors between 19.48 and 35.55 g kg−1 for clay and 1.92 and 2.46 g kg−1 for organic carbon. Estimation errors with HyMap image spectra ranged from 15.99 to 23.39 g kg−1 for clay and 1.61 to 2.13 g kg−1 for organic carbon. A comparison of parameter predictions from different years confirmed the predictive ability of the models. BRDF effects increased model errors in the overlap of neighboring flight strips up to 3 times, but an appropriated preprocessing method can mitigate these negative influences. Using multi-annual image data, soil parameter maps could be successively complemented. They are exemplarily shown providing field specific information on prediction accuracy and image data source.

Description: Much remains to be discovered about the biodiversity of coral reefs in Malaysia, making this area a priority for coral reef research. This thesis aims to provide insights into the patterns of reef coral species richness and the degree of reef connectivity across Malaysia. For the species richness study, the scleractinian coral families Fungiidae, Agariciidae and Euphylliidae were selected as model taxa. Species of these families have a wide geographical distribution in the Indo-Pacific, and they can be found in a large range of reef habitats, from shallow coastal reefs to deep offshore environments. The connectivity of reefs were inferred by examining the genetic population structures of three reef invertebrate species, the mushroom coral Heliofungia actiniformis, the blue seastar Linckia laevigata, and the boring giant clam Tridacna crocea. Data on coral species and specimens of reef invertebrates were collected from reef areas along a geographical range from east to west Malaysia. Reef coral species richness patterns were revealed and indicated common and rare species, as well as potential endemics. Factors to explain the population structure and connectivity patterns across Malaysia are discussed. The findings in this thesis may be relevant for conservation and management of coral reef areas in Malaysia.