Ecological Units and Spatial Pattern in River Ecosystems.

Rivers are advective, largely unidirectional ecological networks whose spatial patterning reflects both catchment and network structural characteristics. I used a headwaters-to-mouth, longitudinal, high-frequency-spatial sampling design to facilitate analyses of the extent and variability of spatial patterning in Midwestern river systems and to test alternate hypotheses about the underlying causes of biological spatial autocorrelation. These analyses establish the conceptual validity of channel segment based classifications used in management settings, and provide guidance for appropriate survey sampling design and statistical analyses in river systems. In the first study I tested the theoretical assumptions underlying the mapping and practical application of riverine ecological units (EUs) within a river mainstem. EUs require concordance between fish and invertebrate assemblage composition and between biological assemblages and environmental variables. Along the Lower Muskegon River mainstem, fish/invertebrate concordances and many environment/biology concordances were strong, resulting in distinct, homogeneous biological assemblages that persisted through time. In the second study I tested the same theoretical assumptions of EUs in a variety of disjunct river tributary systems in Michigan and Ohio. Although fish/invertebrate and environment/biology concordances were very strong in all of the tributaries, downstream tributary channels with substantial stream flow were the only contiguous stream segments with similar environmental and biological character. This suggests a better understanding of spatial pattern and processes in headwater streams is needed to guide effective EU delineation in tributaries. In the third study I explored a common feature of spatial patterning, positive spatial autocorrelation (SAC). SAC was common in both environmental variables and fish assemblage composition, although the magnitude of SAC varied by measure and spatial extent. Strong environment/biology associations accounted for most or all of the SAC in biological assemblages, offering strong support for niche processes as the origin of biotic SAC in these river systems. Likewise, proximity effects on biological assemblages were largely mediated through similarity in the environment. My work here suggests that EUs do provide realistic units to map, inventory, and classify river segments for practical management, and provide a way to abstract and communicate the complex ecological processes and patterns that are characteristic of river ecosystems.PHDNatural Resources and EnvironmentUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111519/1/sparksb_1.pd

SPATIAL ECOLOGY OF BLUE CRAB (CALLINECTES SAPIDUS) IN CHESAPEAKE BAY

Spatial heterogeneity is a striking feature of the blue crab life history and fisheries in Chesapeake Bay. However, a quantitative assessment of their spatial distribution and the factors controlling it has been lacking. Based on 13 years of data from a baywide winter dredge survey, geostatistical and two-stage generalized additive models (GAMs) are used to characterize blue crab distributions and investigate environmental factors responsible for the distribution of mature females, respectively. A landscape-based distance metric, the "Lowest-Cost Path" (LCP) distance, is developed as an alternative to Euclidean distance for kriging in estuaries. Estimates of variogram parameters differed significantly between the two metrics but kriging accuracy did not. Geostatistical abundance estimates show significant declines from 1990 to 2002. The observed relationship between changes in distribution and changes in abundance is suggestive of density-dependent habitat selection. Depth and distance from the Bay mouth were the most important predictors of mature female abundance

A Comparison of Five Statistical Methods for Predicting Stream Temperature Across Stream Networks

The health of freshwater aquatic systems, particularly stream networks, is mainly influenced by water temperature, which controls biological processes and influences species distributions and aquatic biodiversity. Thermal regimes of rivers are likely to change in the future, due to climate change and other anthropogenic impacts, and our ability to predict stream temperatures will be critical in understanding distribution shifts of aquatic biota. Spatial statistical network models take into account spatial relationships but have drawbacks, including high computation times and data pre-processing requirements. Machine learning techniques and generalized additive models (GAM) are promising alternatives to the SSN model. Two machine learning methods, gradient boosting machines (GBM) and Random Forests (RF), are computationally efficient and can automatically model complex data structures. However, a study comparing the predictive accuracy among a variety of widely-used statistical modeling techniques has not yet been conducted. My objectives for this study were to 1) compare the accuracy among linear models (LM), SSN, GAM, RF, and GBM in predicting stream temperature over two stream networks and 2) provide guidelines in choosing a prediction method for practitioners and ecologists. Stream temperature prediction accuracies were compared with the test-set root mean square error (RMSE) for all methods. For the actual data, SSN had the highest predictive accuracy overall, which was followed closely by GBM and GAM. LM had the poorest performance overall. This study shows that although SSN appears to be the most accurate method for stream temperature prediction, machine learning methods and GAM may be suitable alternatives

Spatial and temporal distribution of shorebirds: predicting the effects of habitat change on the Forth Estuary.

First paragraph: Overview One of the many threats to coastal shorebirds globally is the loss or degradation of estuarine intertidal mudflats, a habitat that supports large concentrations of birds both on passage and throughout the winter months. British estuaries comprise 28% of the entire estuarine area of the Atlantic and North Sea coastal states (Atkinson et al. 2001), more than any other European country. Because of this, many UK estuaries are of great importance in both a European and international context for wintering birds (Pollitt et al. 2000). Furthermore, Britain’s estuaries can be particularly important during periods of severe cold weather in continental Europe (Norman & Coffey 1994), when there may be influxes of waterfowl from other coastal regions or inland areas. Some sites also act as cold weather refuges where parts of the estuarine system freeze more slowly than other nearby coastal and inland wetlands and so can provide feeding habitat when other sites are unavailable. Habitat change may not always mean habitat loss, even though large intertidal areas have been removed via landclaim (Evans 1979, McLusky et al. 1992) and engineering works (Schekkerman et al. 1994) or are threatened by the gradual rise in sea level (Austin et al. 2001). Determining the effects of habitat deterioration on shorebirds is often more difficult to predict (Sutherland 1998b) as, although the habitat remains intact, it may reduced in quality due to pollution events (McLusky 1982, McLusky & Martins 1998) or disturbance (Burger 1994, Burton 1996, West et al. 2002). The consequences of habitat change on estuaries are so potentially threatening to shorebird populations that programs of managed realignment (Burd 1995) have been introduced at some sites in order to mitigate such alteration (Dixon et al. 1998, French 1999, Hackney 2000). Such management activity involves the breaching of existing sea walls to allow the land behind to gradually return to estuarine habitat. It has been shown that invertebrates will colonise suitable intertidal habitats and that birds are quick to adapt to such new habitats (Evans et al. 1998)

The Role of Hydrologic Regimes in Driving Morphologic Divergence and the Trait Compositions of Fish Assemblages

The hydrologic regime is an important determinant of the ecological integrity of a stream. Hydrologic regimes are defined by the magnitude, timing, frequency, rate of change, and duration of high and low flow events and capture long term patterns of variability and predictability of water movement in a stream. Flow regimes influence many aspects of the biophysical environment in lotic systems; therefore organisms have adapted to natural flow patterns. We investigated how fish have adapted to flow regimes at both a population and community level. In the first study presented in this thesis, we hypothesized fish exhibit phenotypic divergence to allow them to persist across gradients of hydrologic variability. We combined a comparative field study and mesocosm experiment to investigate the morphological divergence of Campostoma anomalom (central stonerollers) between streams characterized by highly variable, intermittent flow regimes and streams characterized by relatively stable, groundwater flow regimes and assessed the plastic effects of one component of flow regimes, magnitude (water velocity), on fish morphology. We observed differences in shape between flow regimes likely driven by differences in allometric growth patterns, but observed no morphologic plasticity. The second study included in this thesis investigated the relationships between fish traits and hydrologic metrics and determined how traits are spatially auto-correlated within a stream network. We observed complex relationships between fish traits and hydrology; some traits exhibited different responses in different flow regimes. Trait-hydrology relationships were the strongest in groundwater and runoff streams, but very weak in intermittent streams. Spatial factors described more variability in the distribution of fish traits than hydrologic metrics within and between flow regimes and different types of spatial auto-correlation structured trait patterns across flow regimes. Overall, the results of these studies support the implementation of environmental-flow standards and contribute new considerations to include in the development of ecological-flow relationships

Spatial organisation of ecologically relevant high order flow properties and implications for river habitat assessment

PhDThe turbulent properties of flow in rivers are of fundamental importance to aquatic organisms yet are rarely quantified during routine river habitat assessment surveys or the design of restoration schemes due to their complex nature. This thesis uses a detailed review of the literature to highlight the various ways in which plants and animals modify the flow field, how this can deliver beneficial effects; and how turbulence can also generate threats to growth and survival. The thesis then presents the results from detailed field assessments of turbulence properties undertaken on low, intermediate and high gradient rivers to advance scientific understanding of the hydrodynamics of rivers and inform effective habitat assessment and restoration. A reach-scale comparison across sites reveals spatial variations in the relationships between turbulent parameters, emphasising the need for direct measurement of turbulence properties, while a geomorphic unit scale assessment suggests that variations in turbulence at the scale of individual roughness elements, and/or within the same broad groupings of geomorphic units (e.g. different types of pools) can have an important influence on hydraulic habitat. The importance of small-scale flow obstructions is further emphasised through analysis of the temporal dynamics of turbulence properties with changes in flow stage and vegetation growth. The highest magnitude temporal changes in turbulence properties were associated with individual boulders and vegetation patches respectively, indicating flow intensification around these sub-geomorphic unit scale features. Experimental research combining flow measurement with underwater videography reveals that more sophisticated turbulence parameters provide a better explanation of fish behaviour and habitat use under field conditions, further supporting direct measurement of turbulent properties where possible. The new insights into interactions between geomorphology, hydraulics and aquatic organisms generated by this work offer opportunities for refining habitat assessment and restoration design protocols to better integrate the important role of turbulence in generating suitable physical habitat for aquatic organisms.SMART (Science for the MAnagement of Rivers and their Tidal systems) Joint Doctorate Erasmus Mundus programme funded by the European Union

Water Resources Management and Modeling

Hydrology is the science that deals with the processes governing the depletion and replenishment of water resources of the earth's land areas. The purpose of this book is to put together recent developments on hydrology and water resources engineering. First section covers surface water modeling and second section deals with groundwater modeling. The aim of this book is to focus attention on the management of surface water and groundwater resources. Meeting the challenges and the impact of climate change on water resources is also discussed in the book. Most chapters give insights into the interpretation of field information, development of models, the use of computational models based on analytical and numerical techniques, assessment of model performance and the use of these models for predictive purposes. It is written for the practicing professionals and students, mathematical modelers, hydrogeologists and water resources specialists