Morphological effects of vegetation on the tidal-fluvial transition in Holocene estuaries

Vegetation enhances bank stability and sedimentation to such an extent that it can modify river patterns, but how these processes manifest themselves in full-scale estuarine settings is poorly understood. On the one hand, tidal flats accrete faster in the presence of vegetation, reducing the flood storage and ebb dominance over time. On the other hand flow-focusing effects of a tidal floodplain elevated by mud and vegetation could lead to channel concentration and incision. Here we study isolated and combined effects of mud and tidal marsh vegetation on estuary dimensions. A 2-D hydromorphodynamic estuary model was developed, which was coupled to a vegetation model and used to simulate 100 years of morphological development. Vegetation settlement, growth and mortality were determined by the hydromorphodynamics. Eco-engineering effects of vegetation on the physical system are here limited to hydraulic resistance, which affects erosion and sedimentation pattern through the flow field. We investigated how vegetation, combined with mud, affects the average elevation of tidal flats and controls the system-scale planform. Modelling with vegetation only results in a pattern with the largest vegetation extent in the mixed-energy zone of the estuary, which is generally shallower. Here vegetation can cover more than 50 % of the estuary width while it remains below 10 %–20 % in the outer, tide-dominated zone. This modelled distribution of vegetation along the estuary shows general agreement with trends in natural estuaries observed by aerial image analysis. Without mud, the modelled vegetation has a limited effect on morphology, again peaking in the mixed-energy zone. Numerical modelling with mud only shows that the presence of mud leads to stabilisation and accretion of the intertidal area and a slight infill of the mixed-energy zone. Combined modelling of mud and vegetation leads to mutual enhancement with mud causing new colonisation areas and vegetation stabilising the mud. This occurs in particular in a zone previously described as the bedload convergence zone. While vegetation focusses the flow into the channels such that mud sedimentation in intertidal side channels is prevented on a timescale of decades, the filling of intertidal area and the resulting reduction in tidal prism may cause the infilling of estuaries over centuries

Late neolithic and early eneolithic figurative sculpture from the northern of the central Balkans

Figurines stand out as one of the most remarkable features of Neolithic material culture, reflecting the image of Neolithic man and his style of life in a very direct and impressive way. Through various forms and stylizations, figurines reveal details about the clothing, adornment, hairstyle or physical appearance of an individual, while their functional and spiritual character remains a burning issue in archaeological debates. In European Neolithic era, the culture of Vinča stands out as the one characterized by superior craftsmenship in clay modeling, its most prominent aspect being figurative sculpture, one of the most outstanding artistic achievements of the Neolithic era. Although figurative sculpture is present in all phases of Vinča culture (5400- 4500 BC), it could be claimed that its diversity, profusion and high artisanship culminated in the centuries around 4800 BC (Тасић 2008: 144). It is assumed that such flourishing of art is connected with the continual existence of the settlements and stable economy, followed by an organized social system with a developed belief system and established ritual practices. The sample chosen for the statistical analysis of the sex or any other detail is limited to the specimens with preserved body parts on which it is possible to notice the existence of the required element. Thus, if we are interested in the sex of the figurine, the analytical sample will only be comprised of the specimens with preserved body parts on which sex attributes could be expected. The procedure is similar if we are interested in the number of bracelets shown on female figurines, in which case the sample will include only the specimens with defined sex and at least one preserved arm. Such sampling procedure was followed consistently in all the statistical analyses of the presence of certain elements on the figurines. The total of Neolithic and early Eneolithic figurines from northern areas of the Central Balkans is 359 specimens of figurative sculpture, collected from fifteen sites from four narrow geographical areas, marked as Župa aleksandrovačka, lower section of Južna Morava, Ponišavlje and Toplica

Fostering child development with therapeutic dog: Case study

Područje istraživanja i uvođenja pasa pomagača u terapijske, obrazovne i druge procese s djecom i odraslima posljednjih se dvadesetak godina intenzivno razvija. Hrvatska udruga za školovanje pasa vodiča i mobilitet provodi program uključivanja pasa pomagača u obitelji djece s različitim razvojnim teškoćama. Kod djece s cerebralnom paralizom često su prisutne dodatne teškoće, npr.: osjeta, percepcije, kognicije, komunikacije i ponašanja, epilepsija i sekundarne mišićno koštane teškoće U ovom radu opisujemo utjecaj uključivanja terapijskog psa na razvoj različitih razvojnih aspekata kod dvojice dječaka - blizanaca s cerebralnom paralizom, kroz longitudinalno praćenje razvoja od 2008. – 2011. g tj. od predškolske do osnovnoškolske dobi.During the last 20 years research and implementation of programs with service dogs in education, therapies and other process experienced intensive development. Croatian Guide Dog and Mobility Association is implementing a program of including therapy dogs in families of children with disability. In children with cerebral palsy additional diffi culties are often present, such as problems with sense, perception, cognition, communication and behaviour, epilepsy, and secondary muscular skeletal problems. In this work we describe the impact of the inclusion of therapy dog on the development of various aspects of the development of the boys - twins with cerebral palsy, through longitudinal tracking of development since 2008 – 2011, ie. from the period of pre-school to primary school

Ecological impact of changes in intrinsic growth rates of species at different trophic levels

Decreased and increased intrinsic growth rate and abundance of a single species can severely and negatively impact other species in the same food web. Here we compare the wider system effects of decreased and increased intrinsic growth rates of species occupying different trophic levels. Specifically, we derive the change in growth rate of a single (focal) species necessary to cause a 90% reduction in the abundance – a quasi-extinction – of another species in model communities. We find that even relatively small changes, negative as well as positive, in the growth rate of the focal species can cause quasi-extinctions of others. Furthermore, the magnitude of change needed to cause a quasi-extinction depends on the trophic level of the perturbed species. The potential ecosystem impact of such ‘negative' and ‘positive' changes is largely unknown. We argue that such a targeted decrease or increase could be induced by human interference, such as hunting or harvesting, but also by an outbreak or fade-out of an infectious disease. As ecosystems maintain many and diverse infectious agents, these results suggest that these agents may play an important role in the structure and balance of ecosystems

Empirical assessment tool for bathymetry, flow velocity and salinity in estuaries based on tidal amplitude and remotely-sensed imagery

Hydromorphological data for many estuaries worldwide is scarce and usually limited to offshore tidal amplitude and remotely-sensed imagery. In many projects, information about morphology and intertidal area is needed to assess the effects of human interventions and rising sea-level on the natural depth distribution and on changing habitats. Habitat area depends on the spatial pattern of intertidal area, inundation time, peak flow velocities and salinity. While numerical models can reproduce these spatial patterns fairly well, their data need and computational costs are high and for each case a new model must be developed. Here, we present a Python tool that includes a comprehensive set of relations that predicts the hydrodynamics, bed elevation and the patterns of channels and bars in mere seconds. Predictions are based on a combination of empirical relations derived from natural estuaries, including a novel predictor for cross-sectional depth distributions, which is dependent on the along-channel width profile. Flow velocity, an important habitat characteristic, is calculated with a new correlation between depth below high water level and peak tidal flow velocity, which was based on spatial numerical modelling. Salinity is calculated from estuarine geometry and flow conditions. The tool only requires an along-channel width profile and tidal amplitude, making it useful for quick assessments, for example of potential habitat in ecology, when only remotely-sensed imagery is available

Species selection and assessment of eco-engineering effects of seedlings for biogeomorphological landscape experiments

Landscape experiments of fluvial environments such as rivers and deltas are often conducted with live seedlings to investigate effects of biogeomorphological interactions on morphology and stratigraphy. However, such experiments have been limited to a single species, usually alfalfa (Medicago sativa), whereas important environments in nature have many different vegetation types and eco-engineering effects. Landscape experimentation would therefore benefit from a larger choice of tested plant species. For the purpose of experimental design our objective was to identify fast-germinating and fast-growing species and determine their sensitivity to flow conditions during and after settling, their maximum growth, hydraulic resistance and added bank strength. We tested germination time and seedling growth rate of 18 candidate species with readily available seeds that are fast growing and occur at waterlines, plus Medicago sativa as a control. We selected five species that germinate and develop within days and measured properties and eco-engineering effects depending on plant age and density, targeting typical experimental conditions of 0–0.3 m/s flow velocity and 0–30 mm water depth. Tested eco-engineering effects include bank strength and flow resistance. We found that Rumex hydrolapathum can represent riparian trees. The much smaller Veronica beccabunga and Lotus pedunculatus can represent grass and saltmarsh species as they grow in dense patches with high flow resistance but are readily erodible. Sorghum bicolor grows into tall, straight shoots, which add significantly to bank strength, but adds little flow resistance and may represent sparse hardwood trees. Medicago sativa also grows densely under water, suggesting a use for mangroves and perhaps peat. In stronger and deeper flows the application of all species changes accordingly. These species can now be used in a range of landscape experiments to investigate combined effects on living landscape patterns and possible facilitation between species. The testing and treatment methodology can be applied to new species and other laboratory conditions.</p

Empirical Assessment Tool for Bathymetry, Flow Velocity and Salinity in Estuaries Based on Tidal Amplitude and Remotely-Sensed Imagery

Hydromorphological data for many estuaries worldwide is scarce and usually limited to offshore tidal amplitude and remotely-sensed imagery. In many projects, information about morphology and intertidal area is needed to assess the effects of human interventions and rising sea-level on the natural depth distribution and on changing habitats. Habitat area depends on the spatial pattern of intertidal area, inundation time, peak flow velocities and salinity. While numerical models can reproduce these spatial patterns fairly well, their data need and computational costs are high and for each case a new model must be developed. Here, we present a Python tool that includes a comprehensive set of relations that predicts the hydrodynamics, bed elevation and the patterns of channels and bars in mere seconds. Predictions are based on a combination of empirical relations derived from natural estuaries, including a novel predictor for cross-sectional depth distributions, which is dependent on the along-channel width profile. Flow velocity, an important habitat characteristic, is calculated with a new correlation between depth below high water level and peak tidal flow velocity, which was based on spatial numerical modelling. Salinity is calculated from estuarine geometry and flow conditions. The tool only requires an along-channel width profile and tidal amplitude, making it useful for quick assessments, for example of potential habitat in ecology, when only remotely-sensed imagery is available

Species selection and assessment of eco-engineering effects of seedlings for biogeomorphological landscape experiments

Landscape experiments of fluvial environments such as rivers and deltas are often conducted with live seedlings to investigate effects of biogeomorphological interactions on morphology and stratigraphy. However, such experiments have been limited to a single species, usually alfalfa (Medicago sativa), whereas important environments in nature have many different vegetation types and eco-engineering effects. Landscape experimentation would therefore benefit from a larger choice of tested plant species. For the purpose of experimental design our objective was to identify fast-germinating and fast-growing species and determine their sensitivity to flow conditions during and after settling, their maximum growth, hydraulic resistance and added bank strength. We tested germination time and seedling growth rate of 18 candidate species with readily available seeds that are fast growing and occur at waterlines, plus Medicago sativa as a control. We selected five species that germinate and develop within days and measured properties and eco-engineering effects depending on plant age and density, targeting typical experimental conditions of 0–0.3 m/s flow velocity and 0–30 mm water depth. Tested eco-engineering effects include bank strength and flow resistance. We found that Rumex hydrolapathum can represent riparian trees. The much smaller Veronica beccabunga and Lotus pedunculatus can represent grass and saltmarsh species as they grow in dense patches with high flow resistance but are readily erodible. Sorghum bicolor grows into tall, straight shoots, which add significantly to bank strength, but adds little flow resistance and may represent sparse hardwood trees. Medicago sativa also grows densely under water, suggesting a use for mangroves and perhaps peat. In stronger and deeper flows the application of all species changes accordingly. These species can now be used in a range of landscape experiments to investigate combined effects on living landscape patterns and possible facilitation between species. The testing and treatment methodology can be applied to new species and other laboratory conditions