Fish populations were sampled by electrofishing at a variety of sites on the Rivers N. Esk (1992-3) and Dee (1993-4) for comparison with sawbill duckling diets from the same rivers. Sampling methods are described and discussed in relation to other methods and in terms of possible biases. Within electrofished samples species distribution were similar on the two rivers, but more fish were caught per unit effort on the N. Esk. Catch results are described in terms of fish numbers and catch weights of each species from different sections of river and from different sampling times over the summers. Special attention is paid to the distribution and size frequency of salmon, because of their importance in the fish communities of the two rivers and as food for sawbill ducklings. The diets of goosander and merganser ducklings on the study rivers are quantified in terms of species of prey in the diet, size/age classes of fish and relative proportions of these species and classes. Estimates of diet are made from the stomach contents of samples of ducklings. Species composition of the diets are then related to the distribution of fish in those parts of the rivers in which the ducklings forage. Sizes of fish in the diets are then related to the sizes of fish in the duckling foraging areas, taking into account the changes in fish size with location and overtime, and the size (and approximate age) of ducklings. For comparison with diets, fish length data from electrofished samples was interpolated by regression between pairs of consecutive samples and adjacent river sections. This provided expected mean river fish lengths for the dates and locations at which broods were sampled.

No description available.

Ph. D, Faculty of Science, University of Witwatersrand, 2011 / The aim of biological management for black rhinoceros (Diceros bicornis) conservation is to maximise meta-population growth rates to aid species recovery. This research investigated how adaptive resource use in response to seasonal variation in resource availability could affect maximum productive habitat capacity for this critically endangered species. Analysis was based on a population of rhinos which had shown excellent annual growth rates and low inter-calving intervals since re-introduction to Tswalu Kalahari Reserve in the Northern Cape of South Africa in 1995. Acacia haematoxylon, a semi-evergreen species, was identified as the key resource forming the majority of diet contents during the late dry season. Use of this species resulted in a low level of seasonal variation in dietary contents of energy and protein. During the data collection period, energy and protein gains of individual female rhinos were estimated to exceed maximum requirements for reproduction throughout the seasonal cycle. An experiment designed to test the compensatory growth response of A. haematoxylon found that clipping trees in a way that simulated rhino browsing stimulated an increased growth response in the following wet season. This response indicated potential for a facilitatory relationship in the short term. A large proportion of the available area at Tswalu was not used by black rhinos. Home range location and habitat type selection within home ranges during the dry season were positively associated with two shrubveld habitat types containing greater A. haematoxylon biomass than other habitat types. Results from all aspects of field data analysis emphasized the importance of A. haematoxylon as the key dry season resource for black rhino at Tswalu. Field data were used to develop a conceptual model of how seasonally adaptive resource use by black rhinos could determine maximum productive habitat capacity. The crux of the model was to estimate the highest population density at which female rhinos could attain maximum energetic gains for reproduction throughout the entire seasonal cycle. The most limiting period was the nutritional bottleneck during the late dry season. The rationale behind this approach was to enable females to maintain body condition and be capable of meeting nutritional requirements for reproduction throughout the year, thus minimizing inter-calving intervals and maximising population growth rates. Model projections indicated that female rhinos could not attain energy gains for reproduction throughout the dry season in certain habitat types due to low availability of A. haematoxylon. However, model outputs indicated potential for an increase in rhino density by approximately one third in the two favoured shrubveld habitat types, assuming that habitat conditions remained unchanged. Availability of semi-evergreen A. haematoxylon was identified as the key vegetation component determining maximum productive habitat capacity for black rhino at Tswalu. Monitoring available biomass of this species at the end of the dry season could provide a simple plant-based indicator of how close the population is to maximum productive habitat capacity. Managing rhino densities in fenced reserves elsewhere around spatial and temporal availability of key resources may assist in achieving black rhino conservation goals of maximising metapopulation growth rates. Joanne Aileen Shaw

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<p>Fish is considered to be a keystone predator in freshwater habitats. Several studies have shown that the species composition of odonates (Odonata) is different between habitats with and without fish, and that odonates depending on the behaviour and physical characteristics of the individual species react differently to the presence of fish, some positively, some negatively and others not at all. This study aims to study the effect of fish as predators on the odonate community, and especially the little studied effect of the presence and composition of different ecological groups of fish in lakes. 92 Swedish lakes were surveyed for abundances and species compositions of odonates. The composition of fish species in the lakes was determined from official sources and divided into seven ecological groups. While several of the tests for potential interactions between fish and odonates resulted in no significance, the discrimination analyses of the different ecological groups of fish tested against odonate species composition did reveal high classification coefficients, indicating that different ecological groups have different odonate communities. Number of species of fish did also have a fairly high classification coefficient in a discriminant analysis. A combined plot show that two categories of lakes are separating from the others in odonate composition. Both these categories lacked some littoral groups of fish, indicating that littoral fish species may have a strong influence on the odonate community. The study also concluded that both lake size and latitude are potential confounding variables.</p>

The family Brassicaceae includes a number of important species used as vegetables, oilseeds and medicine. The Brassica B-genome is significantly diverged from the A- and C-genomes, and species containing the B-genome possess many valuable agronomic and disease resistance traits. In this thesis, two populations of interspecific crosses between Brassica napus (AACC) and Brassica carinata (BBCC) were studied, and microsatellite (SSR) markers and genomic in situ hybridization (GISH) techniques were applied to characterize the B-genome chromosome introgressions in the advanced backcross populations and their effect on disease resistance, morphological and seed quality traits. A BC2S3 derived doubled haploid (DH) population was genotyped with 184 SSR markers and DH lines carrying stable B-genome chromosomal segments were identified. The GISH assay demonstrated that three of the 60 DHs were substitution lines in which the B-genome chromosome J13 was common to all. The lines with B-genome chromosomes, B+, were significantly different (P <0.01) from the lines without B-genome chromosomes, B- for some morphological and seed quality traits, such as days to flowering, days to maturity and erucic acid content. Further study revealed that resistance to Sclerotinia stem rot (caused by Sclerotinia sclerotiorum) has been inherited from the B or C genomes of B. carinata in some of the DH lines. Several BC3S1 families of another cross, derived from well-characterized BC3 plants containing introgressed B-genome chromosomes, were analyzed using SSR markers and the GISH assay to study the inheritance of the B-genome chromosome(s) and their association with morphological traits. This study revealed that the B-genome chromosomes tend to transfer through generations, either as whole chromosome(s) or as chromosomes without small terminal segments, as evidenced by low recombination frequencies (~ 0%) between the B and A/C-genome chromosomes. These results were supported by the GISH assay and chromosomes counts, and revealed that many of the BC3S1 lines were addition lines carrying extra B-genome chromosomes. / Plant Science

Fish is considered to be a keystone predator in freshwater habitats. Several studies have shown that the species composition of odonates (Odonata) is different between habitats with and without fish, and that odonates depending on the behaviour and physical characteristics of the individual species react differently to the presence of fish, some positively, some negatively and others not at all. This study aims to study the effect of fish as predators on the odonate community, and especially the little studied effect of the presence and composition of different ecological groups of fish in lakes. 92 Swedish lakes were surveyed for abundances and species compositions of odonates. The composition of fish species in the lakes was determined from official sources and divided into seven ecological groups. While several of the tests for potential interactions between fish and odonates resulted in no significance, the discrimination analyses of the different ecological groups of fish tested against odonate species composition did reveal high classification coefficients, indicating that different ecological groups have different odonate communities. Number of species of fish did also have a fairly high classification coefficient in a discriminant analysis. A combined plot show that two categories of lakes are separating from the others in odonate composition. Both these categories lacked some littoral groups of fish, indicating that littoral fish species may have a strong influence on the odonate community. The study also concluded that both lake size and latitude are potential confounding variables.

Increasing attention has been given marine benthic macrofauna due to its importance in marine ecosystems and for its value as bioindicator of environmental changes. One of the most abundant groups among benthic macrofauna are echinoderms which often hold keystone positions in the ecosystems and have proven to be good bioindicators. The aim of this study was to inventory echinoderms and analyze whether species diversity has change over time in Gullmarsfjorden, a fjord with limited water exchange and hence highly sensitive to environmental fluctuations. Also, what may have caused any changes and what potential effects can it have on ecosystems in the fjord, and which species may be valuable as bioindicators. The results show that species diversity of echinoderms has decreased significantly since the early 1900s and the main reduction have occured among species living on/in soft or sandy bottoms. Many of the lost echinoderms species are essential bioturbators and thus important to marine ecosystems. However, Echinocyamus pennatifidum, a sea urchin which is a valuable bioturbator may have established in the fjord during the last century judging from this study. Species like Asterias rubens and Psammechinus miliaris, which are common in the fjord, have also proved to be valuable bioindicators for abiotic changes such as increased CO2-levels and pollution of heavy metals and PCB.

Oilseed crops are being widely evaluated for potential biodiesel production. Seed meal (SM) remaining after extracting oil may have use as a bioherbicide or organic fertilizer. Brassicaceae SM often contains glucosinolates that can hydrolyze into biologically active compounds. Jatropha curcas SM does not contain glucosinolates but contains curcin, a known phytotoxin (toxalbumin). A 14-d greenhouse study was conducted to determine how Sinapis alba (white mustard, WM), Brassica juncea (Indian mustard, IM), Camelina sativa (camelina) and Jatropha curcas (jatropha) applied to soil at varying application rates and incubation times affected seed germination and seedling survival of cotton [Gossypium hirsutum (L.)], sorghum [Sorghum bicolor (L.) Moench], Johnsongrass (Sorghum halepense), and redroot pigweed (Amaranthus retroflexus). Seed meals were analyzed for the presence of glucosinolates, and were applied at 0, 0.5, 1.0 or 2.5 percent (w/w) to Darco fine sand soil and incubated for 1, 7 or 14 d prior to planting. With the weed species, germination and survival was most reduced by 2.5 percent WM SM incubated 1d for Johnsongrass and 14 d for redroot pigweed. Cotton and sorghum seedlings showed strong negative responses to WM SM applications of 2.5 percent at any incubation time. All crops and weed species were most inhibited by 2.5 percent application with any SM, but incubation days varied. Seed meals of each species showed negative results dependent on the incubation day, but overall, WM and camelina SMs were most detrimental compared to IM and jatropha. A second greenhouse study was conducted to determine the availability of nutrients in SMs (WM and IM) to cotton and sorghum compared to inorganic fertilization. Seed meals were applied at 1.0 and 2.5 percent (w/w) and initially incubated for 35 days prior to planting. Emergence of both species was so poor that treatments were incubated for an additional 21 d and replanted. Application rates of 2.5 percent WM and IM SMs reduced sorghum heights and biomass, but only WM had a negative effect on cotton yield. However, the higher of the SM application rates provided greater levels of nutrients compared to the fertilized treatment and control. Results suggested that the type, rate, and timing of SM applications should be considered before land-applying SMs in organic cropping systems in order to successfully manage weeds while producing a profitable crop.

Thesis (Ph. D.)--University of Wisconsin--Madison, 2000. / Includes bibliographical references (p. 251-283). Also available on Internet.