Master of Science / Department of Biology / Craig Paukert / In-stream dredging is a common practice in rivers worldwide that can affect fish and fish habitat. We investigated the magnitude of these alterations and their influence on the fish community of the Kansas River, a large sand bed river. Fishes were collected monthly from June 2010 to June 2011 in Edwardsville and Lawrence, KS from 12, 1-km reaches (three actively dredged, two historically dredged that have not been dredged in at least one month, and seven control reaches) with bottom trawls, seines, and electrofishing. Water depths and velocities were measured with an acoustic doppler current profiler and interpolated in ArcGIS at all 12 reaches. Actively dredged reaches had proportionally more deep water habitat (> 3 m) and lower velocity (< 0.15 m/s) near the river bed than control reaches (P < 0.01 and P = 0.04, respectively). However, the mean proportion of shallow water habitat (< 0.5 m), high velocities near the river bed (> 0.30 m/s), low velocity habitat (< 0.25 m/s), and high velocity habitat (> 0.75 m/s) were similar among all reach types (Ps > 0.05). A canonical correspondence analysis was used to characterize relationships among habitat variables, reach types (actively dredged, historically dredged, and control), and catch per unit effort (CPUE) of fishes in the Kansas River. Mean velocity and depth explained a significant amount of variation in species CPUE; however, reach type was not a significant factor for any of the gear types for any season. Our results show that dredging in Great Plains Rivers can increase depths, but alterations to fish community structure was not evident, likely because many of these fishes are adapted to a range of habitat conditions and are highly mobile.

No description available.

Habitat fragmentation involves the break-up of continuous native vegetation into remnant patches that are set in a matrix of altered habitat. The consequences of habitat fragmentation include the loss of original habitat which is followed by reductions in remnant size that increase edge effects and reduce habitat quality, and also increase the isolation of remnants from one another. Habitat fragmentation is an international environmental concern that also effects Australia. Over the last ten years Queensland has been responsible for some ninety percent of the clearing occurring in Australia, and as a result recorded some of the highest vegetation clearing rates in the world. / thesis (PhDEnvironmentalManagement)--University of South Australia, 2004.

Runnelling is a popular method of physical habitat modification employed on saltmarshes to control pest mosquito populations. The runnelling method involves linking the tidal source to isolated mosquito breeding pools via shallow channels that enable slow water movement of low amplitude tides. Increased tidal flushing inhibits mosquito development. The range of organisms which inhabit saltmarsh are likely to be influenced by altered tidal conditions as they exhibit specific physicochemical requirements for feeding, burrowing or growth. The dynamic nature of saltmarsh may mean that changes to the tidal frequency of a particular region of the saltmarsh promotes extension of marine-like conditions. Because runnels increase the frequency of flooding tidal events in specific regions of the saltmarsh this study predicted that resulting changes would be evident in the physical conditions of saltmarsh substrate, in the transport of buoyant vegetative propagules, in the population characteristics of surface grazing snails and in the density and aperture of crab burrows after flooding and non-flooding tidal events. The physical impacts of runnelling were determined at three marshes which appeared similar in terms of topography, substrate and tidal conditions. Soil water content and consolidation were measured using two sampling protocols: a) comparisons between modified and unmodified shores; and, b) comparisons with increasing lateral distance across the shore from the runnel edge. At one marsh, moisture levels were significantly higher at runnelled than at unrunnelled sites when tides filled the runnels, but this pattern was not found at the other marshes. Soil consolidation was greater at higher shore heights, but was not different between runnelled and unrunnelled shores. Measurements at different lateral distances from runnels demonstrated higher moisture levels and lower consolidation up to 5 m from the edge but not further away. Groups of marked Avicennia marina propagules were released at the three runnelled saltmarshes during flooding and non-flooding tidal events. Groups of propagules released within 10 m of a runnel were always transported significantly further from the starting position and further up the saltmarsh shore after both flooding and non-flooding tides than any other groups. In addition, the pattern of stranding on saltmarsh for significantly different groups was closely associated with the path of runnel construction so that propagules were located either in the runnel or in depressions linked to the runnel that had been isolated mosquito-breeding pools prior to runnelling. It is likely that altered physical soil conditions significantly affected the distribution and size structures of Salinator solida and Ophicardelus spp. snails recorded at the three saltmarshes. The interaction of tidal period and the presence of a runnel contributed to patterns with significant differences between runnelled and unrunnelled regions of the marsh. Generally, the runnel population of snails exhibited flood-like features even during non-flood periods. The distribution and size classes of snails did not differ with lateral distance from runnels. The burrow characteristics of the crab Helograpsus haswellianus were compared to increase the accuracy of estimating abundance from burrow counts. Including only those burrows which were obviously maintained by resident crabs significantly increased the confidence limits of estimating crab abundance using only burrow density counts. This method was applied to runnelled and unrunnelled sites to assess any changes in the density of burrows associated with the presence of runnels. Again, it is likely that physical soil conditions resulting from increased tidal frequency at the runnel did influence crab burrowing with fewer small burrows being found at the runnelled site, low on the shore. In addition, mid- and large-sized burrows tended to dominate close to the runnel edge. Site-specific soil characteristics may help to explain the lack of continuity in patterns associated with runnel effects on non-target saltmarsh resources. While the runnel may increase the soil water content of clayey substrates at some sites it could also result in de-watering of porous sandy soils at other shores. This was evident in the structure of the snail population and distribution of crab burrows which appeared to reflect altered soil physical characteristics associated with the runnel. Runnelling does affect non-target organisms in saltmarsh. However, the scale of impact was usually locally restricted (< 10 m from the runnel edge). The fact that patterns were not recorded at all sites suggests that the influence of runnels is variable and limited by substrate and some biological conditions. Given the efficiency and popularity of runnelling as a physical control method for reducing pest vector mosquito habitat, this study found no evidence to suggest that its use should be discontinued on any ecological basis measured.

Carp (Cyprinus carpio) are alien freshwater fish that are globally widespread and often associated with highly degraded freshwater ecosystems. This study explored carphabitat interactions that could contribute to the worldwide distribution of, and consequent ecological impacts by, carp. Particular emphasis was placed on the role of carp size in these interactions. One component of this study involved a field experiment that was used to quantify the effects of carp biomass density and size-structure on freshwater invertebrate communities and water quality. The treatments in this field experiment comprised different combinations of large (2 kg) and small (0.7 kg) carp, and low (330 kg.ha-1), intermediate (570 kg.ha-1) and high (650 kg.ha-1) biomass densities. Carp impacts were more carp size-dependent than described in previous studies. In particular, carp size was more important than carp biomass density in determining the concentration of total phosphorus and algal biomass. On the other hand, a more even mix of carp sizes increased total nitrogen. The zooplankton and macroinvertebrate taxa that were more abundant in the presence of carp were the taxa most able to avoid carp predation and tolerate habitat changes caused by carp benthivory. To complement the small-spatial scale field experiment, large-scale patterns of carp distribution, biomass density and recruitment were explored among the rivers of New South Wales (Australia) in relation to their physical habitat. In contrast to expectations, and although most recruitment probably occurred at lower-altitudes, the populations with a size structure and biomass density most likely to cause ecological degradation occurred at intermediate altitudes. Furthermore, the distribution of smaller carp (less than or equal to 100 mm, and less than or equal to 300 mm) indicated that the regulation of river flows does not always favour carp populations, particularly during drought conditions. Nevertheless, it was concluded in a review of the carp literature, which incorporated the findings of this study, that invasion by alien carp is most successful in streams with formerly highly variable flows that are now subject to flow regulation. Moreover, carp are likely to enhance their advantage in these waters through habitat modification.

To assess the impact of low-altitude jet overflights on parental care, we examined nest attendance, time-activity budgets, and provisioning rates of 21 Peregrine Falcon (Falco peregrinus) pairs breeding along the Tanana River, Alaska in 1995 and 1996. Several intrinsic and extrinsic factors influenced attributes of nesting behavior. Female nest attendance declined substantially with progression of the nesting cycle, while male attendance patterns were consistent throughout the nesting cycle. Further, although females typically performed most of the incubating, male attendance at the nest area varied considerably among breeding pairs. Both prey item delivery rates and estimated prey mass delivery rates increased with brood size. Prey item delivery rates per nestling, however, decreased with increasing brood size; yet estimated prey mass delivery rates per nestling did not vary with brood size. Peregrine Falcons apparently maintained constant provisioning rates per nestling as brood size increased by increasing average prey size. We found evidence that nest attendance and time-activity budgets of Peregrine Falcons differed during periods of overflights compared with reference nests, but differences depended on stage of the nesting cycle and gender. Males had lower nest ledge attendance during periods when overflights occurred than males from reference nests when data from the incubation and early nestling-rearing stages of the nesting cycle were combined. Females apparently compensated for lower male ledge attendance by attending the ledge more during overflown periods compared to females from reference nests, although this trend was not significant. During late nestling-rearing, however, females perched in the nest area less during periods when overflights occurred than females from reference nests. We did not see a relationship between nest attendance and the number of overflights, the cumulative number of exposures experienced by each nesting pair, or the average sound exposure level of overflights. Nor did we find evidence that nestling provisioning rates were affected by overflights. Low altitude jet overflights did not markedly affect nest attendance, time-activity budgets, or nestling provisioning rates of breeding Peregrine Falcons. / Graduation date: 1999

Graduation date: 1997

Large scale disruption of natural habitats worldwide has led to concern over the effects of habitat fragmentation on wildlife populations. Small scale experiments may be a useful tool for discovering effects of fragmentation over larger landscape scales. I sought to explore the potential for using voles as an experimental model system, at a small scale, to discover mechanisms that may affect other species at different spatial scales. I compared over-winter demography of gray-tailed voles, Microtus canicaudus, in two experimental landscapes, consisting of fragmented and continuous habitat, to assess the effects of habitat fragmentation. I chose winter as the time frame of the experiment because it poses harsh conditions for voles and because seasonal bottlenecks may affect population persistence. Population size, population growth rates, reproduction, recruitment, survival and movements, were monitored using mark-recapture methods in 8, 0.2-ha enclosures planted with alfalfa. The habitat within the enclosures was manipulated into 2 configurations of equal area, 1 large continuous patch (625 m��), and a mosaic of 25 small patches (each 25 m��), prior to the introduction of 12 pairs of animals/enclosure. I hypothesized that population size and growth rates, reproduction, recruitment, and survival would be greater for vole populations in continuous habitats than for populations in fragmented habitats. Additionally, I hypothesized that movements would be more restricted within fragmented habitat because the voles would perceive the area between habitat patches as a barrier. I did not detect significant differences between vole populations in continuous and fragmented treatments. However, populations residing in fragmented habitat showed higher variability over the study period. Populations in both treatments decreased throughout the winter period and all became extinct by the end of the study. Reproduction occurred only during the fall period, and there were no significant differences between treatments. Movements were not different between treatments, or between male and female voles, but movements did increase over time. Survival appeared to be higher for male voles in continuous habitat than in fragmented habitat, but female vole survival was similar between treatments. Survival was influenced by weather conditions, and predation. These results contrast with a previous experiment during the summer season, and indicate that seasonal bottlenecks may be important to consider when studying habitat fragmentation. Extinction of populations in both treatments demonstrates that small populations are extremely vulnerable to both environmental and demographic stochastic events. / Graduation date: 1997

Species diversity is influenced by disturbance in the environment. Ground beetles (Coleoptera: Carabidae) were used as a model taxon to study the effects of disturbance (i.e., time since disturbance) in different habitats along a successional gradient (agricultural fields, old fields, young forests and old forests). Seventy-three species (5139 individuals) were collected during both years of sampling, of which 9 species are introduced species and compose 64.8% of the total catch. In contrast to the predictions of the Intermediate Disturbance Hypothesis, diversity of ground beetles was higher in the agricultural fields and lowest in the old forests. The community composition, as seen with Nonmetric Multidimensional Scaling ordination, in the agricultural fields was the most distinct, while the difference between and among other habitats was less clear, possibly influenced by the introduced species present in the area. The introduced species collected had a significant influence in the total catch as they represented more than half of the total individuals collected and in the ground beetle community composition. The distribution of seven introduced species in Quebec was studied and compared to what was reported in 1975. Five species have a similar distribution, while the distribution range of Harpalus rufipes DeGeer has expanded south and Bembidion obtusum Audinet-Serville might have been dispersing northeast since its introduction.

The objective of this study was to determine the relationship between fish assemblage structure and habitat in streams dominated by an agricultural landscape. Fishes from 20 natural and 20 channelized streams were sampled using electrofishing gear in East Central Indiana. Streams that had been channelized had a lower quality fish assemblage when compared to natural streams as measured by the Indiana V. Eastern Corn Belt Plain Index of Biotic Integrity (IBI). Stream habitat was evaluated using the Qualitative Habitat Evaluation Index (QHEI), which indicated that channelized streams had lower quality primarily due to a loss of heterogeneous habitat. Pearson correlation analysis relating ECB IBI and QHEI was positive and significant, and demonstrated that a reduction in riffle and pool areas associated with channelization was the most significant factor influencing the fish community. Furthermore, species lost when streams are channelized were predictable, and often represented environmentally sensitive species. The results of this study suggested that stream channel alterations have a negative and lasting influence on the fish assemblage which should be recognized prior to any stream development. / Department of Biology