Graduation date: 1980

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 71-75).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-03-28Bitstream added on 2014-06-13T19:05:56Z : No. of bitstreams: 1 petesse_ml_dr_rcla.pdf: 2638872 bytes, checksum: 20218f65e2b863b1164ec169b23f5aa7 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A Represa de Barra Bonita, localizada na bacia hidrográfica do Rio Tietê (20° 31'S; 48° 32'N) -SP, é um ecossistema sujeito a forte estresse ambiental. Além disso, tem grande importância econômico-social pela presença de pescadores profissionais e amadores apesar da produção energetica. Tem superfície de 310 km2 na cota máxima de 451,5 m e profundidade média de 10,1 m. É classificada como polimítica e eutrófica. Nela podem ser reconhecidas três zonas distintas: fluvial, de transição e lêntica. Em cada uma destas zonas foram escolhidas seis estações localizadas em três diferentes tipos de habitat: lateral, desembocaduras de tributários e central, num total de 24 pontos, sendo duas as zonas fluviais consideradas devido a presença de dois rios formadores (Tietê e Piracicaba).. A integridade da comunidade de peixes, foi medida por uma adaptação do índice de integridade biótica (IIB), denominado IAPR (Índice de Assembléia de Peixes em Reservatórios). O índice, assim como o IIB, é composto por diversos atributos da comunidade de peixes (composição, riqueza, abundância, categorias tróficas e condição dos peixes) e mostrou que a maioria das estações pode ser colocada na categoria razoável. Somente as estações de centro pertencem a categoria pobre. Os resultados foram similares no caso do IAPRn e do IAPRP. A correlação do IAPR (em número e em peso) com as variáveis ambientais revelou-se negativa com a profundidade e positiva com macrófitas e mata, confirmando a importância da vegetação aquática e terrestre na margem da represa para a ictiofauna. Os nossos resultados mostram que os peixes realmente podem ser usados para detectar o efeito da degradação nos ecossistemas aquáticos e podem ser usados em programas de monitoramento biológico. / The Barra Bonita Reservoir (lat.: 20° 31'S, long: 48° 32'N, São Paulo State, Brazil), in the Tietê River basin, is an object of relevant scientific interest, having a high social-economic importance, due to hydropower generation and for small-scale and recreational fisheries. Its area is 310 km2 at full surface level of 451.5 m and mean depth of 10.1 m. According to the limnological aspects, it is classified as polymictic and eutrophic. On the longitudinal section, three distinct zones can be recognized: fluvial; transition and lentic. In each of these zones, six sampling sites were selected in three different habitat types: mouth of tributaries, lateral and centre for a total of 24 points for the presence of the two main tributaries (Tietê and Piracicaba rivers). The integrity of fish community was estimate with the adaptation of the Index of Biotic Integrity (IBI) denominated RFAI (Reservoir Fish Assemblage Index). This is composed by different attributes of the fish community: composition, richness, trophic structure and fishes health. The result shows that the stations of mouth of tributary and lateral can be placed in the fair category and those of centre in the poor category. The correlation with physical, chemical and environmental variables was negative with the depth and positive with macrophytes and forest. This confirms the importance of the terrestrial and aquatic vegetation to the ichthyofauna. The results of this thesis indicate that the fishes can be used as meaningful tool for detect the degradation of the aquatic ecosystems. In this context, they can be used in program of biological monitoring.

Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-06-05Bitstream added on 2014-06-13T19:18:41Z : No. of bitstreams: 1 giacomini_hc_me_rcla.pdf: 851295 bytes, checksum: 8fc12f010aee5754cd2c575ced6bf5c5 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A introdução e a disseminação de espécies não-nativas, embora responsável por gerar empregos e lucros, é uma das maiores ameaças à biodiversidade mundial, e também uma causa de sérios prejuízos sócio-econômicos. Sabe-se que apenas uma pequena parcela das espécies introduzidas chega a causar problemas detectáveis. O maior desafio da Ecologia de bioinvasões é determinar que características bionômicas tornam algumas espécies mais propensas a se tornarem invasoras e a causarem danos, bem como as características que tornam algumas comunidades mais susceptíveis aos seus efeitos. A modelagem tem sido sugerida como uma das ferramentas para este fim. Modelos de simulação podem ajudar a entender mecanismos gerais, a desenvolver idéias e hipóteses, bem como direcionar a tomada de decisões. Seguindo esta linha, o presente trabalho teve por objetivo a construção de um modelo baseado no indivíduo (MBI), estocástico e espacialmente explícito, para a simulação da dinâmica de comunidades ecológicas e invasões de espécies. O modelo está voltado para espécies de peixes, mas é geral o bastante para se aplicar a uma série de outros organismos heterotróficos. Cada indivíduo de uma espécie consumidora (peixe) é acompanhado ao longo de todo o seu ciclo de vida, possuindo uma série de características bionômicas que determinam sua estratégia reprodutiva, a potencialidade de interações com outros indivíduos e com recursos basais, que apresentam aumento de biomassa segundo o modelo logístico. O tamanho corporal é utilizado como eixo de nicho trófico, determinando as interações de predação, e também influencia fortemente as características de história de vida por meio de relações alométricas. Experimentos de invasões foram simulados para verificar a relação de algumas características das espécies e das comunidades... / The introduction and spreading of allien species worldwide represent a major threat to global biodiversity, besides promoting serious economic and social impacts. Despite of this, it is well known that only a minor proportion of these introdutions can lead to detectable damages. The main concern of the ecology of biological invasions is to find out which features of species enable them to become succesful invaders and promoting negative impacts on the invaded ecosystems, as well as which kind of communities are most prone to be victims of these impacts. Modelling has been suggested as a promising tool to acomplish this task. Simulation models can help us to understand general mechanisms, giving rise to new ideas and hypotheses, and also advising decision making process. The main goal of the presente dissertation was to elaborate a stochastic and spatially explicit individual-based model (IBM), to simulate community dynamics and species invasions. At its present state, the model is oriented towards fish species, but it can be used to represent a variety of other heterotrophic organisms. In the simulations, every individual of a consumer species (fish) is followed along their entire life cicle. Each one has some key bionomic features that determine its reproductive strategies and the potential for interactions with other individuals and with basal resources, the last growing according to the logistic model. Among all features used, the body size is far the most important. Because it was framed as the determinant trophic niche axis, the body size drives the patterns of predation within communities. By means of alometric relationships, it has also strong influence on the life history of model fish. Using the present model, invasion experiments... (Complete abstract, click electronic address below)

No description available.

Die studie was uitgevoer om te bepaal of warmwaterspesies soos tilapia (Oreochromis mossambicus) en koi (Ciprinus carpio) gebruik kan word as deel van 'n roterende akwakultuur produksie sisteem in die Wes-Kaap. Drie produksiestelsels (drywende hokstelsel; gronddamme en hersirkuleringseenheid) was ge-evalueer vir beide tilapia en koi produksie. Twee verskillende diëte (tilapia, 32% proteien, 'n lae waarde dieet en koi, 32% proteien, 'n hoë waarde dieet) was ook ge-evalueer vir die effek op koi produksie. Tilapia- en koi vingerlinge was teen dieselfde lading (250/hok) in elke produksiestelsel geplaas. By die begin van die proewe het die tilapia vingerlinge 'n gemiddelde gewig van 60-80g en die koi vingerlinge 'n gemiddelde lengte van 30-40 mm gehad. Die visse is twee keer per dag gevoer en data is op 'n maandelikse basis oor 'n periode van 84 dae versamel. Produksie data vir die tilapia versamel was: 1) die gemiddelde daaglikse toename, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die produksie data versamel vir koi wat twee verskillende diëte ontvang het in drie verskillende produksiestelsels was: 1) die gemiddelde daaglikse toename in lengte, 2) die totale voer verbruik, 3) water temperature en 4) mortaliteite is daagliks aangeteken. Die resultate van die tilapia studie het aangedui dat tilapia in die hersirkuleeringseenheid het deurgaans 'n swaarder gewig gehad (p<0.05) as die van die drywende hokstelsel en gronddam stelsel. Terwyl die gronddam stelsel weer 'n swaarder gewig gehad het as die drywende hokstelsel behalwe vir April (171,67 / 39,49 vs 159,33 / 22,15). Nieteenstaande die verskil in begin gewig en eind gewig in die guns van die tilapia in die hersirkuleringseenheid teenoor die ander twee stelsels het die GDT tussen die drywende hokstelsel en die hersirkuleringseenheid nie noemenswaardig verskil nie (1,20 / 0,15 vs 1,40 / 0,24). Die tilapia in die gronddamme het egter swakker (p<0,05) gewigstoename van 0,72 / 0,32 g gehad teenoor die tilapia in die drywende hokstesel 1,40 / 0,24 g en 1,20 / 0,15 g van die tilapia in die hersirkuleringseenheid. Tilapia in die gronddamme het dus ongeveer 45% swakker gemiddelde gewigstoename getoon as die van die drywende hokstelsel en hersirkuleringseenheid. Die produksiestelsel het 'n hoogs betekenisvolle invloed (p<0,001) op die groeipotensiaal van tilapia gehad in hierdie studie. Die gemiddelde totale hoeveelheid voer verbruik was nie statisties verskillend tussen die drywende hokstelsel en gronddam stelsel nie (29,83 / 2,66 vs 30,83 / 5,42), maar wel (p<0,05) vir die hersirkuleringseenheid (29,94 / 0,88). Die VOV het nie verskil tussen die drywende hokstelsel en hersirkuleringeenheid, maar daar was wel 'n verskil (p<0,05) tussen hierdie twee stelsels en die van die gronddamme. Die totale gemiddelde mortaliteite van tilapia was die hoogste (p<0,05) vir die drywende hokstelsel in vergelyking met die gronddamme en hersirkuleringseenheid. Die drywende hokstelsel het 14,67 / 14,61% meer mortaliteite gehad as die gronddamme en hersirkuleringeenheid. Die koi studie se resultate dui aan dat die tipe stelsel het 'n hoogs betekenisvolle (p<0,001) invloed gehad op die gemiddelde toename in lengte van die koi vis vir die somerseisoen. Die tipe dieet het geen invloed op die toename in lengte van koi vis vir al drie die stelsels ge-evalueer, maar die interaksie tussen dieet en die tipe stelsel was wel betekenisvol (p<0.05). Die interaksie tussen die tipe dieet en die tipe stelsel was die hoogste vir die groddamme 136,41 / 32,46 mm en 136,25 / 33,08 mm vir beide tilapia en die koi diëte gevoer. Die gemiddelde totale voer wat deur koi visse in die drie stelsels verbruik is, het wel statisties van mekaar verskil (p<0,05). Koi visse in die gronddam stelsel het meer voer verbruik vir beide die tilapia- en koi dieet (31,03 / 2,01 en 29,67 / 3,57) in vergelyking met die (26,35 / 2,44 ; 26,98 / 0,49 en 5,50 # 0,52 en 6,13 / 0,22) vir die drywende hokke en hersirkuleringseenheid stelsels onderskiedelik. Die % mortaliteite was betekenisvol (p<0,05) vir die verskillende stelsels. Koi visse in die hersirkuleringseenheid het die hoogste mortaliteite gehad vir beide die tilapia en die koi diëte (65,50 / 18,07% en 79,50 / 38,27%) terwyl koi visse in die gronddamme die laagste mortaliteite ondervind het (1,20 / 1,20% en 2,33 / 4,89%) vir beide die tilapia en koi diëte. Die koi in die gronddam stelsel het die beste resultate gelewer en dit is ook moontlik om koi 'n lae waarde dieet te voer sonder nadelige effekte op produksie.

[No abstract submitted] / Land and Food Systems, Faculty of / Graduate

For a variety of stock-recruit systems in which environmental variability is simulated by random normal deviates used as multipliers or divisors Ricker (1958) and Larkin and Ricker (1964) demonstrated the benefits of complete stabilization of escapement as opposed to removal of a fixed proportion of the stock each year. Part I is primarily concerned with the response of these same systems to a pattern of stochastic modification which is more regular in form, a pattern such as might be imagined to result from long-term trends in environmental conditions. In addition, some mathematical properties of these systems are discussed. Part II considers the stock-recruit relationship from a more reductionist or mechanistic point of view. Evidence for differential utilization of spawning areas is presented and spawner distributions in three different environments are compared. These results are discussed in terms of their relevance to existing stock-recruit theory. Also, observations on egg retention and social facilitation are presented. / Science, Faculty of / Zoology, Department of / Graduate

A field evaluation of the dichotomous technique was made using 1965 data from the Rivers Inlet sockeye salmon population. An estimate of preexploitation population size was made with the compositions of the pre- and post-exploitation populations and the catch. The estimate was made through the application of simultaneous equations and a maximum likelihood estimator formulation to changes in population composition resulting from selective removal. Biased data was shown to greatly affect the estimates of population size. A wide range of population estimates was derived from the various dichotomous characters utilized. Graphical analysis of these estimates provided an overall estimate of the population. The physical restrictions of the research area made this estimate of considerable value. Relative to most other population estimation techniques, the dichotomous method has wider potential use because of its less restrictive basic assumptions. This flexibility can be accompanied, however, by a reduction in the accuracy of resultant estimates. / Science, Faculty of / Zoology, Department of / Graduate