ESTADO ECOLÓGICO DE LA CUENCA BAJA DEL ARROYO SAN BERNARDO, SIERRA DE LA VENTANA, ARGENTINA

Process-based, spatially-explicit modelling of riparian forest dynamics in Central Europe

Biodiversity loss is the silent crisis of the 21st century. Human activities are drastically altering the diversity of life on Earth, yet the extent of this transformation is shrouded by our limited information on biodiversity and how it is changing. Emerging technologies may be suited to fill this information gap, and as a result increase our capacity to measure and manage natural systems. Acoustic monitoring is a remote sensing technique that is rapidly reshaping the temporal and spatial scales with which we can assess animal biodiversity. Through recording and analyzing soundscapes—the collection of sounds occurring at a given place and time—we can assess biodiversity, habitat condition, and environmental change. However, the relationships between soundscapes and these three ecological dimensions are still in the early phases of categorization, especially in aquatic systems. This dissertation investigates how soundscapes can be used to measure biodiversity, habitat condition, and environmental change in aquatic habitats. It addresses several knowledge gaps: First, I develop a framework for classifying unknown sounds within a soundscape, which I use to measure the acoustic diversity and dynamics within a tropical freshwater wetland. Second, I demonstrate that soundscapes can reflect the resilience of animal communities following disturbance events. Altered soundscapes revealed that Hurricane Maria, which swept through Puerto Rico in September 2017, impacted dry forest animal communities more than adjacent coral reef communities. Third, in kelp forest habitats off the coast of California, USA, I showed that soundscape variables correlated with ecological variables associated with regime shift in kelp forests, including urchin density, kelp cover, and fish diversity. Overall, this dissertation demonstrates that soundscape recording and analysis is a promising way to assess the ecological conditions of aquatic systems.

Biodiversity loss caused by environmental changes has been increased year by year. The aquatic ecosystems have been impacted as habitats are modified, most likely by human activities. Few studies have examined how biological assemblages at different spatial scales are determined by environmental gradients. We aim to understand the influence of environmental factors on the distribution and diversity of macroinvertebrates in Northern Thailand. A total of 21,391 individuals belonging to 79 families in 15 orders were identified. The order Diptera is one of the most abundant taxa in this study (family Chironomidae). The cluster analysis of macroinvertebrates and environmental factors clearly divides the areas into two groups of disturbed (downstream) and undisturbed (headstream) stations. CCA results revealed that the turbidity, conductivity and BOD are the most important factors that could influence macroinvertebrate assemblages in this study. The results also provided the basic information about the ecological status as monitored by the distribution of organisms in aquatic systems. However, it is necessary to increase data reliability by continuing to monitor other biological communities in the long-term in order to define adequate strategies for diagnosing the integrity of stream ecosystems. Keywords: Macroinvertebrate diversity; Environmental factors; Spatial distribution

Ecological impact of phytoinvasions in Ukraine

The need for river bank protection in an ecologically appropriate manner has led to the investigation of shallow groynes as a nature-oriented countermeasure against bank erosion. Shallow groynes are in-stream structures which have a horizontal crest and are submerged even during low flow conditions in order to minimize the effect on the flood level. Rather than enhancing the resisting forces like traditional bank protection measures, e.g. riprap, shallow groynes are used to redirect the attacking flow away from the river bank. In this way, the bank itself becomes available as habitat and the water-land interface is rehabilitated or preserved. Moreover, the shallow groynes increase the heterogeneity of the flow field, bed topography, and bed material, which is one of the key elements requested by the EU Water Framework Directive to improve the ecological condition of rivers. However, guidelines are necessary for a successful and sustainable design of shallow groynes. The objective of the study was to develop design guidelines for shallow groynes in river bends by experimentally investigating the design parameters, namely groyne inclination, length, width, location and spacing in a river bend. The experiments were carried out in a curved flume in the laboratory of Leichtweis-Institut fur Wasserbau (LWI). The three-dimensional flow field was measured with an Acoustic Doppler Velocimeter. The hydraulic boundary conditions were kept constant throughout the experiments. A reference run was carried out without a groyne providing the basis for quantification of the hydraulic effects due to the shallow groynes. The optimum groyne parameters were defined based on the highest reduction of stream-wise velocity close to the outer bank. The manipulation of the flow field throughout the bend was investigated with a single groyne as well as with a group of groynes varying the number of groynes as well as the spacing. Further experiments with a fixed bed and a mobile outer bank confirmed the effectiveness of shallow groynes for bank protection. The results of the different sets of experiments were combined to develop a design method for bank protection with shallow groynes throughout a river bend. The method incorporates geometric parameters of the bend as well as the hydraulic boundary conditions.

Spatio-temporal dynamics and hydro-ecology of intermittent streams in eastern Australia

With the implementation of European Water Framework Directive, good chemical status for all water bodies and good ecological status for all natural waters are to be reached by 2015. Considering sediments as an inseparable part of river basins, current sediment quality guidelines derived only from chemical concentrations can not guarantee the ecological services of sediments in supporting aquatic ecosystems. There is therefore a need to develop an integrated quality indicator (IQI) addressing the ecological relevance to assist the chemically dominant sediment assessment for a better river basin management. A weight of evidence approach integrating sediment ecotoxicities and functional diversity of sediment microbial community in nutrient cycling was employed. The sediment ecotoxicity describes the potential risk of contaminants on biota through bioassays, which integrate effects of pollutants and environmental conditions. Two standardised bioassays, algal growth inhibition test and bacterial contact assay, were applied for different exposure routes. The functional diversity of microbial community in nutrient cycling provides the supporting service in aquatic ecosystem, which is necessary for the production of other organisms and maintain the conservation of nature. The diversity in nutrient cycling was addressed by the heterotrophic carbon substrates utilisation patterns and autotrophic nitrification was tested as the key ecological function. In addition, substrates induced DMSO reduction method was proposed to characterise the microbial functional diversity including both heterotrophic and autotrophic activities. A temporal investigation of sediment quality using these lines of evidence was carried out in the river Elbe to define a possible response range. The results were further integrated using a fuzzy rule based model taking biological uncertainties into account to develop quality classes and indices characterising sediment quality in ecotoxicities, functional stability (heterotrophic), and nitrification (autotrophic). All three quality classes and indices were combined and presented using quantitative triangles and linguistic tables as the final IQI. The effect of aging and resuspension on sediment quality was evaluated with the developed IQI as an example to illustrate its unexpected impact on nutrient cycling despite the reduced risk from contaminants on biota. The IQI provides a transparent measure communicating the complex ecological relevant sediment quality with simplicity, which offers a clear overview coupling causes as well as actions for decision makers and can be explained to and understood by non scientists.

Impact of hydropeaking on fish and their habitat

Dams are highly controversial as; on the one hand, they provide vital goods such as drinking water or renewable energy and essential services such as flood protection and, on the other hand, threaten lotic ecosystems in several ways. The adverse impact of reservoir dams on lotic ecosystem biodiversity and integrity is significant. In particular, changes in the flow regime are considered to play a major role and have a fundamental impact on benthic invertebrate communities. In order to pursue the Sustainable Development Goals of the United Nations or other environmental protection guidelines, such as the European Water Framework Directive, at the same time, adjustments of dam operation will be necessary. The present thesis aims to identify potentials for dynamic dam operation, to improve the ecological integrity of downstream river segments and thereby refers to environmental flows. The provision of management options for environmental flows requires a sufficient understanding of hydro-ecological relationships, a description of the altered and unaltered regime as well as a reliable understanding of the ecological consequences and responses to those existing alterations as well as of the provided management options. Therefore, I first quantified the role of hydrology in the context of other prominent stressors and identified hydro-ecological relationships (Chapter I). To do so, I analysed the general effects of hydrology on benthic invertebrate communities and compared them to other prominent stressors (land use, morphology, physico-chemistry) within a broad dataset from streams in the German lower mountain range (72 samples from 51 sites). Stressor data were contrasted to benthic invertebrate data using i) partial canonical correspondence analysis (pCCA) to quantify the community-level response and ii) path analysis to investigate the cause-effect pathway structure (hydro-ecological relationships) of single stressors affecting invertebrate metrics either directly or indirectly (i.e. mediated by other stressors). Further, I evaluated the effects of dams on taxonomic and functional components of macroinvertebrate biodiversity to estimate the effects on ecosystem function and resilience in Chapter II. I compared and correlated different taxonomic and functional diversity metrics, investigated the taxonomic and functional community structure and the degree of specialization of invertebrate communities of downstream stretches of nine large dams, which were compared to communities of eight unaffected tributary sites. Finally, I investigated possible management options that are likely to be beneficial for the riverine macroinvertebrate community below dams, by analysing the current effects on hydrological, and in addition on thermal and bed sediment regimes at downstream stretches of dams and correlated them with key metrics of macroinvertebrate communities (Chapter III). Therefore, I contrasted metrics of hydrological alteration derived from discharge time series (daily means over 10 years), time series of water temperature (15-min intervals over one year), and records of deposited fine sediments against macroinvertebrate samples from pairs of river reaches downstream of dams and of comparable tributaries. The results of Chapter I prove the important role of hydrology as a strong and directly effective ecological determinant and pointing at the same time at the high potential of implementing e-flows. Hydrological metrics revealed an important role in directly shaping macroinvertebrate community structure and significantly affected metrics relevant for ecological status assessment. The analysis of abiotic changes (Chapter III) showed that numerous, seasonally distinguishable hydrological alteration patterns, lowered temperatures, increased fine sediments, and a deficit of pebbles and cobbles characterized downstream stretches. The results of Chapter III showed that downstream stretches were characterized by numerous, seasonally distinguishable hydrological alteration patterns, lowered temperatures, increased fine sediments, and a deficit of pebbles and cobbles. The analysis of single functional trait diversity carried out in Chapter II showed that the alteration patterns found reduce the habitat and food availability as well as the resilience of invertebrate communities in downstream stretches. As a result, taxonomic and functional diversity were decreased in downstream stretches and showed especially losses of sensitive species groups (Chapter II & III). The comparison with undisturbed reference streams allowed me to derive specific management options that could mitigate the negative impact of hydrologic alterations and accumulations of fine sediments downstream of dams (Chapter III). In general, the results of the thesis showed that environmental flows (e-flows) need to consider the complex character of hydrological regimes (more than just thresholds of minimum flows) and need to be implemented in a seasonal context. The implementation of e-flows has, especially in highly regulated catchments, a high potential to increase the ecological status of our running water bodies (not only those directly downstream of dams).

Instream flow needs (IFN) assessment studies are performed to provide guidelines for stream water management and to assess the impacts of different water projects such as weirs, dams and stream diversions on the available fish habitat. The physical habitat simulation is one of the IFN assessment methods and also a powerful tool in management of river ecosystem that has not become a common method in many countries, yet. The main aim of the present research is representing the ability of habitat simulation technique in river ecosystem management. Delichai stream in Tehran province in Iran is selected as the case study. Based on the results habitat simulation technique has considerable ability for dynamic assessment of IFN and river habitat evaluation along the longitudinal and latitudinal cross sections and it can also present the spatial habitat suitability distribution in various months of the year dynamically. IFN assessment with habitat simulation technique has advantages related to other methods like that of the Tennant method and wetted perimeter method and creates the least discussion between river environmental managers and stakeholders. In the study stream of this research due to the variation of ecological condition for the target species, three different values for IFN in various months of the year were estimated and it was seen that the habitat near the stream bank requires more protection and restoration projects.

As the ecotone of the aquatic ecosystem and terrestrial ecosystem,riparian ecosystem has unique vegetation,soil,topography,geomorphology and hydrology features and a series of environmental,social and economic functions.Hence to improve the management of resources,ecology and environment of the riparian ecosystem for sustainable development of watershed has become a significant issue in the watershed ecology and ecosystem ecology. The characteristics of the riparian ecosystem were analyzed.The riparian ecosystem was the result of three-dimensional interaction between terrestrial ecosystem and aquatic ecosystem.As a typical ecotone,the frequent anthropogenic disturbances,geomorphological process and hydrological process could influence the riparian ecosystem in the ecological process and species succession.According to the aim of ecosystem management,the uniqueness,complexity and dynamics of the riparian ecosystem should be taken into account. After introduction of the progress in the riparian ecosystem management,the concept and elements of the riparian ecosystem management were defined.A practical process for riparian ecosystem management was given in this paper,which consisted of seven steps.The first one is scoping of object,area,stakeholders,etc.,then comes to the problem diagnosis.The third step is goal setting,including broad and operational goals.After the above processes,the riparian ecosystem was integratively assessed,in which ecosystem health and integrity were taken as indictors for assessing ecosystem structure,and ecosystem service was valued to reflect ecosystem function.The management policy and its implementation was the sixth step,which was the most important one in this process,and feedback and adaptive adjustment was the last step in the process.Four key problems were identified for riparian ecosystem management,including the research scales,the riparian width of management,the coordination of ecological values and local riparian ecosystem management. According to the developments and present studies on the riparian ecosystem management,the theory of the riparian ecosystem management,induction of ecological model,application of the interdisciplinary approaches,application of the 3S technologies and modern mathematics method as well as quantitative case study should be the front problems for further studies of the riparian ecosystem management.

Quantifying responses of aquatic insects to environmental change

This study aims to analyze the diversity, composition, and community structure of odonata in the highland and lowland ecosystems and the type of lotic and lentic waters and analyze the description of land use and its relationship with diversity odonata. There are 8 research locations namely Sumber Maron, Sumber Sirah, Sumber Taman, Bureng River, Umbul Gemulo, Arboretum, Coban Rais River, Coban Talun River. Measurement of biotic and abiotic factors in odonata habitat and land use analysis using GPS and ArcGIS program ver 10.5, data analysis using the Shannon Wiener diversity index (H'), evenness index (E), Important Value Index (IVI), and similarity index Bray-curtis. The results showed that the total number of Anisoptera in lotic aquatic ecosystems was 619 individuals divided into 13 species from 3 families, in the lenticular aquatic ecosystem was 533 individuals divided into 15 species from 3 families. This study concludes that the diversity of species in the highlands is higher than in the lowlands, and the diversity in the lentic ecosystem is higher than that of the lotik ecosystem and odonata has its own tolerance to land use as their habitat especially with minimal human disturbances.

中国井冈山生态系统多样性

Natural and Anthropogenic Drivers of Water Quality in the Normanby Basin and Princess Charlotte Bay, Cape York Peninsula, Australia