Four species of net-spinning caddisflies, Hydropsyche simulans Ross, Cheumatopsyche lasia Ross, Cheumatopsyche campyla Ross and Chimarra obscura (Walker) are common in the regulated portions of the Brazos River. Hydropsyche simulans spun capture nets with the largest meshdimensions; the two Cheumatopsyche species' nets had the next largest meshes, and Chimarra obscura spun nets with the smallest dimensions. Cheumatopsyche lasia and C. campyla constructed nets with similar sized meshes. The number of individuals m~2 and standing crop biomass were not significantly different among low, medium, and high velocities. Early hydropsychid instars fed on detritus while later instar H. simulans and C. campyla had larger proportions of animal material. Guts of later instar C. lasia individuals had a greater percentage of algae and diatoms.

The primary aim of this thesis is to detail and evaluate the appraisal frameworks and techniques employed on river restoration projects in the UK. This research evaluates the extent to which restoration projects have implemented the appraisal frameworks and techniques proposed in the practical restoration literature, and examines barriers to the incorporation of appraisal into river restoration projects. An ideal type appraisal framework is developed in this thesis and is used as a tool against which to evaluate the nature and extent of UK river restoration project appraisal. This research was undertaken through a national and a regional investigation of appraisal procedures. The national investigation is designed to be extensive and aims to draw out the basic dimensions of river restoration projects and appraisal. The regional investigation, in contrast, intensive adopting a case study approach which examines in detail how appraisal has and has not been implemented. The national investigation involved a questionnaire survey, sent to 161 people involved in 440 river restoration projects (80% response rate achieved). The regional investigation of the Thames region of the Environment Agency (EA) focused in detail on three case study sites (River Ravensbourne, River Cole and Upper River Kennet) undertaking twenty-five in-depth interviews with restoration practitioners. This enabled the appraisal and decision-making structures of these three projects to be evaluated. This thesis argues that it is not only the structure of a project's appraisal which influences a project's trajectory but also the nature and composition of the decision-making structure. The influence of scientific and lay knowledge in decision making is also explored. This thesis concludes by drawing together key empirical, theoretical and practical findings from these investigations. The results of this research are discussed and evaluated against how effectively UK river restoration projects incorporate the ideal type appraisal framework proposed in Chapter 2. The results of this research are further evaluated in the light of a workshop on river restoration appraisal (undertaken in November 2002) where appraisal frameworks are discussed and ways of including appraisals in river restoration projects are put forward.

Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

River flow regime is fundamental in determining lotic fish communities and populations, and especially of salmonid fishes. Quantifying the effects of human induced flow alteration on salmonids is a key question for conservation and water resources management. While qualitative responses to flow alteration are well characterised, a more intractable problem is quantifying responses in a way that is practical for environmental management. Using data drawn from the Environment Agency national database, I fitted generalised linear mixed models (GLMMs) using Bayesian inference to quantify the response of salmonid populations to the effects of impounding rivers, flow loss from rivers due to water abstraction, and the mitigating effects of flow restoration. I showed that in upland rivers downstream of impounded lakes, the magnitude of antecedent summer low flows had an important effect on the late summer abundance of 0+ salmonids Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). In contrast, the abundance of 1+ salmon and brown trout appeared to be largely unresponsive to the same flows. I demonstrated that short-term flow cessation had a negative impact on the abundance of 1+ brown trout in the following spring, but that recovery was rapid with negligible longer-term consequences. I further established that flow restoration in upland streams impacted by water abstraction provided limited short-term benefits to salmonid abundance when compared with changes at control locations. However, while benefits to salmonid abundance were limited, I detected important benefits to the mean growth rates of 0+ and 1+ brown trout from flow restoration. I discuss the implications of my findings for salmonid management and conservation and propose a more evidence-based approach to fishery management based on robust quantitative evidence derived using appropriate statistical models. The current approach to flow management for salmonids requires revision and I recommend an alternative approach based on quantitative evidence.

A survey of small mammals on eight islands in the Columbia and Willamette Rivers near Portland, Oregon was conducted in 1974. The islands were Govermnent , Sand, Lemon, McGuire and Sandy Islands in the Columbia River and East, Ross and Hardtack Islands in the Willamette River. The objectives of the study were to ascertain and compare the kinds, distribution and relative densitites of small mammals . A variety of traps was used to capture the animals including Museum Special Rodent Traps , back- break mouse traps, scissor and guillotine- type stab mole traps , Sherman traps , modified Young traps and pitfalls . Most traps were set in linear transects . Trapping was conducted with the objective of sampling the major habitats on each island. Observations of scats, tracks , burrows and dead animals were also noted. One species of small marmnal , Sorex vargrans , was found on all eight islands . Microtus was found on five islands and Peromyscus maniculatus on four islands . Two islands yielded Scapanus townsendii. Glaucomvs sabrinus was found on only one island. I hoped that evidence would be found to prove or disprove that current theories of island biogeography would apply to river islands. However, data in this study were inadequate to allow calculation of precise indices of population densities . Therefore, I was unable to determine if theories of island biogeography do apply to these river islands.

Widespread Lake Bonneville sediments have been modified by river aggradation and degradation associated with Holocene fluctuations in the Great Salt Lake. Exposures of exceptionally abundant and well-preserved molluscan deposits in the Bear River Valley, Utah, allow detailed paleoenvironmental reconstruction of Holocene environments. The exposed basal unit consists of largely unfossiliferous deltaic silts and clays deposited during Lake Bonneville time ( roughly 11,000 - 13,000 yr B. P.). An unconformity representing at least 2000 yr separates the deltaic material from overlying highly fossiliferous stream sands. Eight species of molluscs, comprising a single community, occupied this low energy stream environment at 7690 ± 270 14C yr B. P. A second unconformity separates these sands from a dark brown silt unit deposited by a river-associated environment, most likely an over-bank marsh, at 2420 ± 135 14C yr B. P. Nine species of molluscs, comprising 3 communities, were present in this environment. Analysis of size-frequency distributions, percentage of pelecypod valves, preservation, and orientation of the shells that were present in each environment suggests that the 7690 ± 270 14c yr B. P. fossil assemblage has been only slightly altered by biostratinomic processes. The younger assemblage has also been altered, with the size-frequency curves of the smallest gastropods displaying normal distributions. Geomorphic and stratigraphic data from the Malad River show that water levels in the Great Salt Lake twice rose and fell significantly during the Holocene epoch. The oldest rise, to an altitude of at least 1288 m, occurred before 7690 ± 270 yr B. P., perhaps in response to a worldwide period of climatic cooling. This high-stand was followed by a fall of lake level roughly corresponding to the classic Hypsithermal Interval, about 7000 - 5000 yr B. P. A second rise occurred by 2420 ± 135 yr B. P., when the Great Salt Lake rose to approximately 1286 m. During this second rise, the Malad River overflowed its levees and later, as the Great Salt Lake receded for a second time, the river was captured by a headward-cutting tributary of the Bear River. The regional distribution of the fossiliferous deposits was controlled by the time at which capture occurred. Capture of the Malad channel by the Bear River occurred after the last fossiliferous sediments were deposited; thus no fossils are found downstream from the point of capture.

No description available.

Drylands occupy about one-third of the world's land surface area and rivers in these regions have less predictable flow regimes than those in humid tropical and temperate regions. Australia's dryland river-floodplain systems cycle through recurrent periods of floods and droughts, oflen resulting in extreme hydrological variability. As a result, these systems have been described as having a 'boom and boost' ecology with periods of high productivity associated with flooding. Not surprisingly, flow and its variability have been recognised as major driving forces in the ecological functioning of Australian rivers and responses to flow variability from fish and aquatic invertebrates have been reasonably well described. Furthermore, the reduced amount of water reaching floodplain waterbodies due to river regulation has been held responsible for successional changes in aquatic biota and, consequently, the resources available for both fish and invertebrates. However, information regarding the impacts of water resource development has generally focused on within-channel processes of Australian rivers, not on floodplains, which are arguably more affected by water development. The following dissertation is concerned with how different types of natural and modified floodplain lagoons are able to trophically support their fish communities in the floodplain of the Macintyre River, Border Rivers catchment (QLD/NSW), a regulated dryland river. This study focuses on the influence of flooding and the implications of an extended dry period, and different levels of flow regulation, on the feeding ecology of selected fish species (Ambassis agassizil, Lelopotherapon unicolor and Nematalosa erebi) between 2001 and 2003. Food resources consumed by fish are hypothesised to vary in response to flooding, when inundation of isolated lagoons and vast floodplain areas can result in a burst of primary and secondary productivity. Given the permanently elevated water levels of some regulated floodplain lagoons, fish diets are hypothesised to be less variable in these floodplain habitats in comparison to diets of fish from floodplain lagoons with natural flow and water regime. Feeding ecology is examined firstly, in terms of diet composition of selected fish species, using stomach content analysis, and secondly, in relation to possible energy sources sustaining fish (using stable isotope analysis) in selected floodplain lagoons and a site in the main channel of the Macintyre River. The information produced should allow managers to take variations in food resources, food web structure and dietary ecology into account in management regimes for refugia and dryland systems in general. Factors such as diel and ontogenetic variations in dietary composition and food intake by fish are shown to considerably affect ovemll dietary patterns of each study species. Therefore, it is important to understand the contributions of such factors to the variability of fish dietary patterns before performing studies on resource use by fish in floodplain habitats of the Macintyre River. Major food categories consumed by the study species were zooplankton, aquatic invertebrates and detrital material. Zooplankton was of particular importance as this food item was ingested by all three study species at some stage of their life history. Spatial and temporal variation in diet composition of the study species was mostly associated with changes in prey items available across floodplain habitats and between seasons (summer/winter). The low magnitude of flooding events during the study period is arguably the most likely factor influencing the lack of patterns of variation in fish diets in floodplain habitats subject to flooding, whereas in non-flooded lagoons the observed dietary variation was a consequence of successional changes in composition of the aquatic fauna as the dry season progressed. Water regime had an important effect on differences in fish diet composition across lagoons, but further evaluation of the influence of flooding is needed due to overall lack of major flooding events during the study period. Autochthonous resources, namely plankton, were the basis of the food web and phytoplankton in the seston is the most likely ultimate energy source for fish consumers, via planktonic suspension feeders (zooplankton). Nevertheless, organic mailer could not be disregarded as an important energy source for invertebrates and higher consumers. In general, the present study does not provide support for the major models predicting the ftinctioning of large rivers, such as the River Continuum Concept and Flood Pulse Concept, which argue that allochthonous organic matter either from upstream or from the floodplain are the most important sources of carbon supporting higher consumers. In contrast, the Riverine Productivity Model would be more appropriate to describe the food web and energy sources for consumers in the Macintyre River floodplain as this model suggests that local productivity, based on autochthonous phytoplankton and organic matter, ftiels food webs in large rivers. The results of this study suggest that factors known to affect phytoplankton production in floodplain lagoons (e.g. flow regulation, turbidity and nutrient/herbicide inputs) must be seriously considered in current landscape and water management practices.

Estuarine benthic assemblages are often numerically dominated by polychaetes. The limits of these populations are determined by larval, and probably to a lesser extent adult movement. A previous study (Newton 1996), indicated that planktonic polychaete larvae were very abundant over the summer months in the Hopkins River; however, the identification and source of these larvae was not known. Defining the extent of a population, and therefore the likelihood of that population recovering following a perturbation, is crucial for effective estuarine management. This study investigated both the likely source of the larvae, (i.e. estuarine or marine) and the extent of larval dispersal within and between estuaries by addressing the following questions: Which taxa produced the planktonic larvae? Are these taxa resident estuarine species? Are the larvae of different taxa evenly distributed within the estuary or do physicochemical parameters or other factors influence their abundance? Are the same larvae found in other estuaries along the coast? and Is there exchange of these larval taxa with the marine environment and other estuaries? Larvae were identified and described by culturing commonly occurring planktonic larvae until adult characteristics appeared. The spionids, Carazziella victoriensis and Prionospio Tatura, numerically dominated the plankton in the Hopkins and the spionid, Orthoprionospio cirriformia was recorded from the Hopkins, Curdies and Gellibrand estuaries. Two spionids, Carazziella sp. and Polydora sp. were identified from tidal waters. Mouth status and physicochemical conditions (salinity, temperature and dissolved oxygen) were monitored in each estuary. Whereas the Merri and Gellibrand estuaries were predominantly stratified over the sampling period, the Curdies was more often well mixed and the Hopkins varied from well mixed to stratified. The duration of mouth opening and hence the opportunity for larval exchange also varied in each estuary. The Merri River was closed for 13.5% of days over the study period, the Gellibrand River for 18.4%, the Hopkins River for 49% and the Curdies River for 71.0%. The distributions of larvae at spatial scales of metres, 100s of metres and kilometres were investigated within a single estuary. While the same larvae, C. victoriensis, P. Tatura and bivalve larvae, were found along the length of the Hopkins estuary the abundances varied at different spatial scales suggesting different processes were influencing the distribution of P. Tatura larvae, and C. victoriensis and bivalve larvae. The distribution of larvae between several estuaries was investigated by monitoring meroplankton at two sites at the mouth of each of the four estuaries approximately monthly (except for winter months). Different meroplanktonic assemblages were found to distinguish each estuary. Further, C. victoriensis and P. Tatura larvae were only recorded in the Hopkins but larvae of the spionid, Orthoprionopio cirriformia were detected in the Hopkins, Curdies and Gellibrand estuaries. The extent of larval exchange with other estuaries and the marine environment was determined by monitoring tidal waters. Settlement trays were also deployed to determine if larvae were moving into estuaries and settling but not recruiting. P. tatura larvae were not detected in the tidal waters of any estuary and while C. victoriensis and O. cirriformia were found in both flood and ebb tides there was no evidence of movement of theses taxa to other estuaries. Larvae of the spionids, Carazziella sp. and Polydora sp., were found in tidal waters of each estuary but were rarely detected in the plankton within the estuaries. Neither species was found as an adult in background cores from any estuary, nor with the exception of a few individuals in the Merri, were they detected in settlement trays in any estuary. I conclude that the source of the larvae of C. victoriensis, P. Tatura and O. cirriformia is estuarine and while C. victoriensis, and O. cirriformia move in and outh of the source estuary in tidal waters there was no evidence for movement to other estuaries. The spionids, Carazziella sp. and Polydora sp were considered to be marine and while they moved in and out of estuaries in tidal waters they did not usually settle in the estuaries. The results of this study are a crucial first step in the development of ecological models to better understand dispersal in seasonally closed estuaries that are typical of southern Australia. This study emphasises the unique physicochemical characteristics and biological assemblages within these estuaries and the need for estuarine management to reflect these differences.