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No. of bitstreams: 1 giovanneambrosioferreira.pdf: 11308277 bytes, checksum: 29c09d7d3d127c6be8192883098b796f (MD5) Previous issue date: 2011-02-25 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O livre acesso de gatos (Felis silvestris catus) a áreas externas da residência de seus proprietários (chamados semi-domiciliados), quando em ambientes naturais pode ocasionar predação sobre animais silvestres, competição alimentar com carnívoros nativos, e ainda potencializara veiculação de zoonoses. Informações a respeito do comportamento destes animais em fragmentos de mata atlântica são raros, desta forma, este estudo objetivou avaliar: a) os itens encontrados na dieta e sua variação sazonal através da análise de amostras fecais; b) a área de vida e os padrões de atividade por meio de rádio telemetria; c) as diferenças individuais na dieta e a disposição das fezes nos territórios por meio do método da marcação de isca de gatos semi-domiciliados encontrados em um fragmento remanescente de Mata Atlântica localizado ao sul do município de Ilha Comprida – SP. Resultados coletados entre setembro de 2009 e setembro de 2010 demonstram que mesmo recebendo alimentos dos proprietários, a espécie apresentou uma dieta oportunista e generalista, com pouca variação sazonal (X2 = 6,754; p = 0,4549). As presas mais consumidas foram insetos (21,26%), seguidos por mamíferos (14,24%) e aves (4,11%). Machos residentes em propriedades ausentes de fêmeas demonstraram maiores área de vida e sobreposições sobre as áreas dos demais gatos, que apresentaram valores semelhantes entre si. Os horários de maior atividade ocorreram no período crepuscular noturno, principalmente nos horários de 20-22h e 02-04h; enquanto o período entre 14-16h apresentou menor registro. Maiores atividades registradas durante a estação seca, todavia, machos demonstraram maior atividade noturna, em ambas as estações, enquanto fêmeas maiores atividades diurna, principalmente durante a estação seca. As amostras fecais encontradas próximas ao centro de atividade, geralmente estavam enterradas, enquanto à medida que se distanciavam, podiam ou não estar enterradas. Ocorreram poucas variações na dieta entre os sexos. Entretanto, fêmeas mais novas predaram animais menores (insetos); fêmeas mais velhas predaram também vertebrados maiores; enquanto para os machos observou-se o inverso. A diversidade de itens de presas nativas encontrados na dieta demonstra a capacidade adaptativa e o comportamento inato de predação da espécie. A pequena diferença encontrada entre as estações reflete na pequena variação sazonal encontrada no período amostrado. Os resultados indicam que a disponibilidade e abundância de recursos (alimento e abrigo) foram os fatores mais importantes na determinação das áreas de vida de fêmeas, enquanto a disponibilidade e acesso a estas, seriam os determinantes para os machos. Sugere-se que o padrão de atividade sofra influência das variações sazonais. A maneira como as fezes são encontradas no ambiente estão relacionadas ao status hierárquico ou questões comportamentais e ecológicas de seu produtor. Sendo assim, informações importantes sobre a dieta e comportamento de caça individuais foram obtidas por meio da identificação individual de suas fezes. Os resultados obtidos por este estudo contribuem para pesquisas que visem à preservação de espécies vulneráveis às influencias causadas pela presença desta espécie em ambientes naturais, ou ainda que busquem obter esclarecimentos sobre a saúde e o bem estar destes animais, espécies nativas e seus proprietários. / Free access for cats (Felis silvestris catus) to areas outside the residence of its owners (called semi-resident), when in natural environments may cause predation on wildlife, food competition with native carnivores and more, increase the zoonoses placement. Information about the behavior of these animals in the Atlantic forest fragments are rare, thus this study aimed to assess: a) the items found on diet and its seasonal variation by analyzing fecal samples; b) the home range and patterns of activity by radio telemetry; c) individual differences in diet and feces disposal in the territories by the method of marking bait semidomiciled cats found in an Atlantic forest fragment located south of the city of Ilha Comprida – SP. The results collected between September 2009 and September 2010 show that even getting food from the owners, the species had a generalist and opportunistic diet, with little seasonal variation (X2 = 6,754, p = 0,4549). The most consumed preys were insects (21,26%), followed by mammals (14,24%) and poultry (4,11%). Males residing in properties absent from females had larger home ranges and overlap the areas of other cats, which showed similar values. The time of greatest activity occurred in the evening twilight period, mainly during 20-22h and 02-04h, while the period between 14-16h showed the lowest record. Major activities recorded during the dry season, however, males showed greater nocturnal activity in both seasons, while females more daytime activities, especially during the dry season. The fecal samples found near the center of activity usually were buried, and as much as they distanced from the center they could be buried or not. There were few variations in diet between the sexes. However, younger females preyed on smaller animals (insects); older females also ate higher vertebrates, whereas for males the opposite was observed. The diversity of prey items found in the native diet demonstrates the adaptiveness in innate behavior and predation of the species. The small difference found between the seasons reflected in the low seasonal variation found in the sample period. The results indicate that the availability and abundance of resources (food and shelter) were the most important factors in determining the home range of females, while the availability and access to them, and are the determinants for males. It is suggested that the activity pattern is influenced by seasonal variations. How feces are found in the environment are related to the hierarchical status or behavioral and ecological issues of its producer. Thus, important information about diet and individual hunting behavior were obtained through individual identification of feces. The results of this study contribute to research aimed at the preservation of species vulnerable to influences caused by the presence of this species in natural environments, or even seek clarification about the health and wellness of these animals, native species and their owners.

This work gives an overview of the composition of the diet of bats in the eastern Mediterranean and the Middle East, discusses the structure of bat communities in different bioregions of the area in terms of hunting strategies and resource partitioning and last but not least, how echolocation and morphological characteristics of bats affect the composition of the diet. Although some samples were relatively small therefore it is necessary to look soberly at their informative value, and thus their importance is undeniable. The study in some cases provides completely the first information regarding the composition of diet in several species. Asellia arabica mainly catches Coleoptera (Scarabaeidae), Triaenops persicus hunts Lepidoptera, but Heteroptera, Coleoptera (Scarabaeidae) and Orthoptera too, while Triaenops parvus is a specialist in hunting Lepidoptera. Rhinopoma muscatellum hunts mainly Formicoidea, followed by Coleoptera (Melolonthinae) and Heteroptera, Rhinopoma hadramauticum hunts Formicoidea. Lepidoptera of different size, Heteroptera and Coleoptera are the prey of Chaerephon nigeriae. Pipistrellus hanaki has a wide niche breadth as other species of the genus Pipistrellus. In this study Brachycera, Auchenorrhyncha and Coleoptera primarily occurred in its diet. Not yet described species of...

This work gives an overview of the composition of the diet of bats in the eastern Mediterranean and the Middle East, discusses the structure of bat communities in different bioregions of the area in terms of hunting strategies and resource partitioning and last but not least, how echolocation and morphological characteristics of bats affect the composition of the diet. Although some samples were relatively small therefore it is necessary to look soberly at their informative value, and thus their importance is undeniable. The study in some cases provides completely the first information regarding the composition of diet in several species. Asellia arabica mainly catches Coleoptera (Scarabaeidae), Triaenops persicus hunts Lepidoptera, but Heteroptera, Coleoptera (Scarabaeidae) and Orthoptera too, while Triaenops parvus is a specialist in hunting Lepidoptera. Rhinopoma muscatellum hunts mainly Formicoidea, followed by Coleoptera (Melolonthinae) and Heteroptera, Rhinopoma hadramauticum hunts Formicoidea. Lepidoptera of different size, Heteroptera and Coleoptera are the prey of Chaerephon nigeriae. Pipistrellus hanaki has a wide niche breadth as other species of the genus Pipistrellus. In this study Brachycera, Auchenorrhyncha and Coleoptera primarily occurred in its diet. Not yet described species of...

Mercury accumulation of upper trophic level marine fishes is a growing concern for human consumers. Diet is the primary source of mercury bioaccumulation in both fish and humans and yet remains unexamined in many intensely fished regions such as southern New England (SNE). The feeding ecology and mercury concentrations of recreationally caught albacore (Thunnus alalunga) and yellowfin (T. albacares) tunas, shortfin mako (Isurus oxyrinchus) and common thresher (Alopias vulpinus) sharks and dolphinfish (Coryphaena hippurus) were evaluated. Important prey were identified and also measured for total mercury content. Seventy percent of the predator fishes sampled in this study had mercury concentrations greater than the EPA recommended 0.3ppm, and included shortfin makos (2.65 ± 1.16ppm), threshers (0.87 ± 0.71ppm) and albacore (0.45 ± 0.14ppm). Mercury concentrations were lowest in dolphinfish (0.20 ± 0.17ppm) and yellowfin (0.32 ± 0.09ppm). Length was positively correlated with mercury content and bioaccumulation rates were linear for tunas and dolphinfish, while exponential for both shark species. Small schooling fishes (Pomatomus saltatrix, 0.110 ± 0.102ppm) were the primary prey of shortfin makos. Shortfin squid (Illex illecebrosus, 0.028 ± 0.005ppm) was a principal and consistent dietary component of both tunas and dolphinfish diets. The diets of SNE dolphinfish and yellowfin tuna were more invertebrate dominated than other regions previously examined. Though the method of sample collection for this study biases toward larger individuals, these are the sizes of fish targeted by anglers, generally for human consumption.

La Barge à queue noire Limosa limosa est un oiseau limicole communément rencontré tout au long de l’année sur le territoire Français. Les individus présents sur la partie ouest de l’Europe sont représentés par deux sous-espèces : la sous-espèce L. l. limosa, dite barge à queue noire « continentale », est principalement observée pendant les phases de migration et en très faibles effectifs reproducteurs sur les marais ouest Atlantique; la sous-espèce L. l. islandica, dite « islandaise », est quant à elle, exclusivement présente en hivernage le long des côtes atlantiques et de la Manche. L’étude menée au cours de ces travaux de thèse porte principalement sur la barge « islandaise » en dehors de la période de reproduction sur les sites d’hivernage le long de la façade atlantique Française. Contrairement à L. l. limosa, la population de L. l. islandica connaît sur l’ensemble de son aire de répartition, une expansion aussi bien en termes d’effectif qu’en nombre de sites fréquentés. La synthèse des effectifs nationaux hivernants montre que la population hivernante en France suit cette même tendance, avec une progression de 1350 à 27000 individus au cours des vingt dernières années. Actuellement, la France accueille environ 30 % de la population sur un nombre de sites grandissant mais néanmoins restreint, principalement représentés par les Réserves Naturelles littorales abritant des vasières intertidales utilisés comme zone d’alimentation. À partir de données biométriques, génétiques ou encore des historiques de vie des oiseaux équipés de bagues couleurs, les périodes de présence des deux populations sur le territoire Français ont pu être mis à jour. De plus, au sein de la sous-espèce islandaise, plusieurs durées d’hivernage en France ont été avancées, pouvant varier de 2 à 8 mois selon les individus. La phénologie des effectifs étudiée sur chacun des sites suggère une utilisation très variée des sites ainsi que de nombreux échanges entre ces sites au cours d’un même hiver. Couramment utilisée dans la compréhension de la distribution des populations d’oiseaux, la disponibilité de la ressource trophique a également été étudiée au regard du régime alimentaire de la Barge queue noire à partir d’échantillonnages de macrofaune, de collecte de fèces mais aussi d’analyses d’isotopes stables. Au cours de l’hiver, à l’échelle des Pertuis Charentais, les barges montrent deux régimes distincts mais néanmoins monospécifiques. Elles s’alimentent de rhizomes de zostères (Zostera noltii) sur les herbiers des vasières de l’Ile de Ré et de bivalves (Macoma balthica) sur les vasières nues. Au cours de l’hiver, il est supposé que la déplétion de ces ressources conduit à une redistribution des effectifs de barges sur de nouvelles zones d’alimentation voire de nouveaux reposoirs. Les deux régimes alimentaires sont majoritairement retrouvés à l’échelle de la distribution nationale des barges. Néanmoins, leurs distributions au sein des sites français dépend des caractéristiques sédimentaires, des interactions intra et interspécifiques, de la disponibilité de reposoirs de marée haute et des dérangements tels que la chasse. Ce travail a permis d’établir de solides connaissances et aboutit à la collecte de données détaillées et complémentaires qui vont permettre de tester les modèles théoriques de distribution spatiale des organismes à l’échelle d’une région de leur aire de distribution. / The Black-tailed godwit Limosa limosa is a shorebird species commonly observed in France throughout the year. Two sub-species are dissociated in West European. The so called “continental” Godwit L. l. limosa is observed in France during migration cycles and some pairs breed in marshes on the Atlantic coast; the so called “Icelandic” Godwit winters exclusively along coast of the Western Europe. This present work mainly investigates the wintering ecology of Icelandic–godwit in coastal mudflats of France. Contrarily to the continental sub-species, the whole Icelandic-godwit L. l. islandica population increased quantitatively as long as the number of sites used. In France, national counts pointed out that wintering population follows this trend and have increased from 1350 to 27000 individuals during the last twenty years. This population represents now around 30% of the whole islandica population but individuals stage in large flocks in a very limited number of sites, mainly included in Nature Reserves. From standard biometrics, molecular analyses and resighting data, phenologies of the both sub-species can then be specified for France. Furthermore, this study allowed to define how long the wintering period lasts in France for Icelandic-Godwits, between 2 and 8 months depending on individuals. Phenology at site scale suggested that godwits used several sites throughout the winter. As currently used for understanding the distribution of bird populations, trophic resource availability was studied in regard to the diet of the Black-tailed godwit from macrofauna sampling, droppings collection and stable isotope analyses. At the Pertuis Charentais scale, two feeding behaviors were clearly distinguished: seagrass grazing (Zostera notlii) or bivalve probing (Macoma balthica). Food depletion along the winter is expected to lead to the decrease of local populations, and to the selection of new feeding area or roost. Considering the distribution of the species at the national level, the diets were recorded depending on the mudflats’ characteristics. Even if food distribution is commonly used to understand at first the bird population distribution, our observations point out that, here at a local level, more parameters may influence the wintering distribution such as sediment characteristics, intra and inter-specific interactions, high tide roosts availability and human disturbances as the hunt. This work allowed to establish a solid knowledge and to collect many complementary data to test the distribution theories on the Black-tailed Godwit population wintering in France.

Innerhalb des Zeitraumes 2002 bis 2004 wurden in Berlin Untersuchungen zur Nahrungsökologie verschiedener Vogelarten durchgeführt, wobei auch die Konsequenzen wie der Fortpflanzungserfolg analysiert wurden. Neben der Aufnahme der Brutvogel- (2002) und Wintervogelgemeinschaft (2002/2003) auf fünf Pf à ca. 20 ha entlang eines Urbangradienten, wurden die Arten Blaumeise, Grünling, Haussperling und Turmfalke speziell untersucht. Auf den fünf Pf, die sich hinsichtlich Baustruktur, Flächennutzung und Vegetationsanteil unterschieden, wurden 35 Brutvogelarten festgestellt. Anhand der Artenzahlen ist deutlich ein Urbangradient zu erkennen: Das Stadtzentrum (Ze) wies 12, das Gewerbegebiet (Ge) 15, die Hochhaussiedlung (Ho) 17, die Einfamilienhaussiedlung (Eh) 18 und der Park (Pa) 28 Arten auf. Im Verlauf der Wintervogelkartierung wurden insgesamt 3763 Individuen in 30 Arten registriert. Im Pa wurde bei der Blaumeise der höchste Reproduktionserfolg mit knapp 5,9 Ausgeflogenen/Brut festgestellt. Anhand des Zustandes der Nestlinge und des Fortpflanzungserfolgs sowie durch die Dokumentation des Fütterungsverhaltens der Altvögel anhand von Camcorderaufnahmen wurde deutlich, dass das Nahrungsangebot für die Meisen im Pa am besten war. Der carnivore Turmfalke wurde 2002 bis 2004 unabhängig von den fünf Pf an zehn Nistkastenstandorten untersucht, die in drei unterschiedlichen Zonen lagen: City (Ci), Mischgebiet (Mi) und ländliche Zone (LZ). Als Besonderheit wurden in jedem Nistkasten in der Ci in jedem Jahr anthropogene Nahrungsreste, z. B. Kotelettknochen, gefunden, was zeigt, dass sich der Turmfalke, neben der Nutzung von Gebäuden als Nistplatz, auch hinsichtlich seiner Nahrungsökologie an den Menschen anpasst. Dass die Blaumeise, der Grünling und der Haussperling insgesamt in Berlin gut zurechtkommen, selbst in der Innenstadt, indiziert die Beutetierliste des Turmfalken: Der Haussperling stand an erster Stelle, der Grünling an zweiter und die Blaumeise an sechster Stelle der gefangenen Vogelarten. Besonders in einer Metropole wie Berlin besteht weiterer Forschungsbedarf, da die Synurbanisierung verschiedener Vogelarten ständig voranschreitet. / From 2002 to 2004 the feeding ecology of different bird species was studied in Berlin. Thereby consequences like the success in reproduction were also examined. Beside the survey of the breeding bird (2002) and the winter bird community (2002/2003) in five study sites each covering an area of approx. 20 ha along an urban gradient, the species Blue Tit, Greenfinch, House Sparrow and Kestrel were researched in detail. In total, 35 breeding bird species were found in the five sites, which were characterised by different building structure, land use and vegetation cover. Considering the species` number, an urban gradient was clearly visible: In the city centre (Ze) 12 species were recorded, in the industrial area (Ge) 15, in the high-rise apartment building area (Ho) 17, in the detached family housing (Eh) 18 and in the park (Pa) 28 species. During the winter bird census a total of 3,763 individuals and 30 bird species was recorded. In the Pa, the highest reproduction success of the Blue Tit (5,9 fledglings/brood) was recorded. On the basis of the nestlings'' condition and the reproduction success, as well as by documentation of the feeding behaviour of the adult birds by means of video recording (camcorder), it became clear, that food supply was best in the Pa for the Tits. From 2002 to 2004, the carnivorous Kestrel was examined independent from the five study sites at ten nesting sites (nest boxes), which were located in three different zones: City (Ci), Mixed Zone (Mi) and Outskirts (LZ). Striking were anthropogenic food items, like cutlet bones, found in every nest box in the Ci in all three years, which shows the adaptation to humans not only with regard to nesting sites (buildings) but also with regard to feeding ecology. The prey species list of the Kestrel indicates that Blue Tit, Greenfinch and House Sparrow get along well all in all, also in the city centre: the House Sparrow ranked first, the Greenfinch second and the Blue Tit sixth of the captured bird species. Especially in a metropolis like Berlin there is need for further research, because the synurbization of different bird species progresses permanently.

Le refroidissement global et les oscillations entre cycles glaciaires et interglaciaires du Pléistocène inférieur ont pour conséquence une alternance entre milieux steppiques et forestiers, favorisant par là-même renouvellements et dispersions fauniques dont celui du genre Homo.Dans les interprétations paléoenvironnementales basées sur les assemblages fauniques, les cervidés, parmi les plus abondants mammifères, sont classiquement considérés comme forestiers, mais ce paradigme ne reflète pas la complexité de la diversité écologique réelle des cervidés.L'analyse texturale de 921 spécimens représentant les 5 cervidés actuels à l'écologie référencée a permis d'établir une robuste base de données et d'attester du lien significatif entre micro-usure dentaire et ressources végétales. L'analyse de 547 cervidés fossiles issus de 15 localités européennes souligne leur grande diversité écologique. Eucladoceros ctenoides et Metacervoceros rhenanus présentent une alimentation plastique. Leur analyse permet l'identification de réponses alimentaires adaptatives aux modifications environnementales liées aux oscillations climatiques. Ces deux cervidés, eurytopiques, constituent des indicateurs écologiques incontournables. La composante forestière supportée par la présence des cervidés est ici remise en cause ; les cervidés étant plus diversifiés écologiquement. L'analyse de la texture de la micro-usure dentaire des cervidés présents dans des sites européens, où la présence du genre Homo a été avancée, vise à identifier le type potentiel d'habitat favorable à sa dispersion en Eurasie. / The early Pleistocene is a period of global cooling and climatic oscillations punctuated by glacial and interglacial cycles. This period of climatic instability leads to an alternation of steppe and forest habitats resulting in faunal renewals and dispersals, including Homo dispersal.In paleoenvironmental reconstructions based on faunal assemblages, deer, which are among the most abundant mammals, are traditionally considered forest dwellers. However, this paradigm is far from reflecting the real complexity of deer ecological diversity.Via the textural analysis of 921 representatives of the 5 extant European deer with known ecology, a solid reference database has been setup. It attests of the significative link existing between dental micro-wear and vegetal resources. The analysis of 547 fossils from 15 European localities underlines the ecological diversity among fossil deer. Eucladoceros ctenoides and Metacervoceros rhenanus are plastic in their diet. The analysis of such deer allows the identification of dietary adaptive answers to environmental modifications resulting from climatic oscillations. Being eurytopic, they constitute essential proxies for paleoenvironmental reconstructions. The results challenge the link existing between the occurrence of deer and the presence of forest habitats, as deer are ecologically more diversified.The textural analysis of deer from European human bearing localities aims at characterizing potential habitats favorable toward Homo dispersion in Eurasia.

In der Studie wurde die Ernährung und die Verteilung von larvalen und juvenilen Stadien von Plötze (Rutilus rutilus (L.)) und Barsch (Perca fluviatilis L.) untersucht. Untersuchungsgewässer war der Feldberger Haussee, ein geschichteter eutropher Hardwassersee, der seit über 15 Jahren biomanipuliert wurde. Der Bestand an Barschen war in diesem Gewässer im gesamten Biomanipulationszeitraum sehr gering (< 1% der Gesamtfischbiomasse). Längerfristig stabilisiert, aus wissenschafticher Sicht, eine hoher Bestand an piscivoren Barschen die Effekte der Biomanipulation. Ziel der Untersuchung war daher die Überprüfung der Hypothese, dass das Vorhandensein von Konkurrenz um die Ressource Zooplankton zwischen den juvenilen Barsch und Plötzen für den geringen Barschbestand verantwortlich ist (PERSSON & GREENBERG 1990, PERSSON et al. 1991). Die Ergebnisse der Untersuchungen ließen sich in folgenden Punkten zusammenfassen: i) Der juvenile Barsch segregierte in der Hochsommer- bis Herbstperiode in eine spezielle Nahrungsnische. Die beiden Fischarten unterschieden sich deutlich bezogen auf die Art der bevorzugten Zooplankter (0+-Barsch vorwiegend Eudiaptomus, Diaphanosoma, Leptodora; 1+/2+-Plötzen fraßen Cladocerennahrung Bosmina und in hohen Anteilen auch Daphnia). Separation und Aufteilung der Zooplanktonresourcen konnte auch für die bevorzugte Größe der Zooplankter beobachtet werden. Die hohen Wachstumsraten und der gute Konditionszustand des juvenilen Barsches sowie das Fehlen von Wintermortalität ließen konkurrenzinduzierte Mortalität als Begründung für den geringen Bestand nicht glaubhaft erscheinen. ii) Die räuberbedingte saisonale Mortalität der juvenilen Barsche in der Hochsommer- bis Herbstperiode ließ sich bei den 0+-Barschen und 1+-Barschen jeweils auf bis zu 90% einschätzen. Dadurch wurde auch ein starker Jahrgang (wie 1997) innerhalb der ersten zwei Lebensjahre auf bis zu 99% reduziert. iii) Als Alternativhypothese wurde aus den Ergebnissen der Studie und den Bedingungen am Feldberger Haussee gefolgert, dass eine Kombination von langer zooplanktivorer Phase und einem hohen Bestand an effektiven pelagischen Piscivoren (wie Sander lucioperca L.) für den geringen Barschbestand verantwortlich ist. / In the study the feeding behaviour and distribution of larval and juvenile stages of roach (Rutilus rutilus (L.)) and perch (Perca fluviatilis L.) was examined. The object of the study was the Lake Haussee, an stratified eutrophic hardwater lake that was biomanipulated for more than fifteen years. Over the whole period of biomanipulation the portion of perch population did not reach the level of one percent of the total fish biomass. From the scientific point of the view, a high biomass of piscivorous perch may stabilize the effects of biomanipulation in the long run. The aim of the study was to evaluate the hypothesis of strong competitive interaction between juvenile roach and perch for zooplankton, which could be responsible for the minor population of perch in lakes (PERSSON & GREENBERG 1990, PERSSON et al. 1991). The results of the study can be summarised as follows: i) In the period of midsummer to autumn juvenile perch segregated to a special food niche. In comparison to 1+/2+-roach, which fed on cladocerans (e.g. Bosmina and a high portion of Daphnia), 0+-perch preferred Eudiaptomus, Diaphanosoma and Leptodora. Thus, partitioning and separation were also observed for size-selectivity. Furthermore, the high growth rates and the good state of condition of the young perch as well as the lack of winter mortality did not indicate a competitive-induced mortality in the Lake Haussee. ii) In the period of midsummer to autumn the predator-induced seasonal mortality of juvenile perch (groups like 0+/1+) was estimated nearly up to 90 percent. Thereby, also a strong age group (like 1997) of juvenile perch was reduced up to 99 percent within the first two years of life. iii) The results of this study supported an alternative hypothesis: the morphological conditions of Lake Haussee, a prolonged zooplanktivore period of juvenile perch in combination with a strong stock of an effective pelagic piscivore predator (like Sander lucioperca L.) are responsible for the low perch stock.

Made available in DSpace on 2016-06-02T19:29:30Z (GMT). No. of bitstreams: 1 3328.pdf: 5855954 bytes, checksum: e2ae16f838808ae8684dce0854e76126 (MD5) Previous issue date: 2010-04-06 / This study was conducted in the middle portion of the Teles Pires river basin and four tributaries, from october 2007 to july 2009, the Alta Floresta region in northern Mato Grosso. The objective was to study the reproduction and diet of the cachara Pseudoplatystoma punctifer. Sampling of fish were collected monthly by using longlines placed on the banks of rivers, Stopped, Four Bridges, Santa Helena, Apiacás, Teles Pires and in Lagoa da Mata, The specimens captured were killed and underwent biometry were removed gonads and stomach identifying the sex and stage of gonadal maturation the naked eye. We estimated the degree of stomach fullness, frequency of occurrence for each item and feeding. Measurements of abiotic variables were collected at the sites of P. punctifer. We made monthly measurements of water temperature, transparency, conductivity, dissolved oxygen and pH always two stations in each area to collect fish. We collected 398 fish, and of these 223 are females and 175 are male, accounting for 56% and 44%, respectively. There was a differentiation in size and weight of the ovaries with the variation of the reproductive cycle, the ovaries of young immature body weights minimum of 4.5 g, reaching a maximum weight of 630 g in adult females mature testes weight ranged on average from 2.6 g to 474.0 g young immature to mature adults. During the water regime was a variation in the absolute frequency of occurrence of females and males at different stages of gonadal development. The young, males and females predominated in all the phases with higher frequency in the flood of 2008 for both sexes, reproductive adults predominated in the flood of 2009, with most males, males and females in reproductive adults not predominant in all home phases of the hydrological regime in the flood of 2009 for females and males from 2008 to ebb. You can measure the spawning P. punctifer occurs between January and February, with completion in april 2009, coinciding with the highest values of rainfall in the region. For females the estimated L50 was 72.5 cm and for males was 72.0 cm, (L100) is greater in females at 106 cm for males, 94.5 cm. Females were more numerous in the length classes between 63.0 cm to 81.0 cm, males in length classes from 58.0 cm to 78.0 cm. The sex ratio is presented as follows: between the months of october 2007 to march 2008, the ratio was 1 male to female and three months from november to december 2008 was the first male to 17 females. The estimated averages of condition factor (K) depending on the water regime, were higher among males in the full flood of 2008 and 2009, the female values were balanced, the condition presented by individuals during the study period did not vary significantly depending on the water regime. Among abiotic factors analyzed, rainfall indirectly contributing to reproduction of P. punctinfer. The seasonality, characterized by the phases of water regime in the region, influenced the greater supply of items to the diet, especially the full. Despite the great contribution of fish in the diet of P. punctifer, diversity of food items indicates a carnivorous diet generalist, because it presents no selectivity of prey including several families of fish and other food groups. The presence of terrestrial vertebrates in this study may indicate an opportunistic habit of the species. / O presente estudo foi desenvolvido na porção média da bacia do rio Teles Pires e em quatro tributários, no período de outubro de 2007 a julho de 2009, na região de Alta Floresta Norte de MT. Objetivou-se estudar a reprodução e a dieta do cachara Pseudoplatystoma punctifer. A amostragem dos peixes foram através de coletas mensais utilizando-se de espinhéis dispostos nas margens dos rios, Parado, Quatro Pontes,Santa Helena, Apiacás, Teles Pires e na Lagoa da Mata, Os exemplares capturados foram sacrificados e submetidos à biometria, foram retiradas as gônadas e estomago identificando-se o sexo e o estádio de maturação gonadal a olho desarmado. Estimou-se o grau de repleção estomacal, freqüência de ocorrência para cada item e índice alimentar. As medições das variáveis abióticas foram realizadas nos locais das coletas de P. punctifer. Foram feitas medições mensais da temperatura da água, transparência, condutividade elétrica, oxigênio dissolvido e pH sempre em duas estações em cada área de coleta dos peixes. Foram coletados 398 peixes, sendo que destes 223 são fêmeas e 175 são machos, correspondendo a 56% e a 44%, respectivamente. Houve uma diferenciação no tamanho e no peso dos ovários com a variação do ciclo reprodutivo, os ovários de jovens imaturas apresentaram peso mínimo de 4,5 g, atingindo o peso máximo de 630 g nas fêmeas adultas maduras o peso dos testículos, variou em média de 2,6 g para os jovens imaturos a 474,0 g para os adultos maduros. Durante o regime hídrico houve uma variação na freqüência absoluta de ocorrência de fêmeas e machos, em diferentes estádios de desenvolvimento gonadal. Os jovens, machos e fêmeas, predominaram em todas as fases com maior freqüência na cheia de 2008 para ambos os sexos, os adultos reprodutivos predominaram na cheia de 2009, com maioria de machos, os machos e fêmeas adultos não reprodutivos em repouso predominaram em todas as fases do regime hidrológico na cheia de 2009 para fêmeas e na vazante de 2008 para machos. Pode-se mensurar que a desova de P. punctifer ocorre entre janeiro e fevereiro, com término em abril de 2009, coincidindo com os maiores valores de precipitação pluviométrica na região. Para fêmeas o L50 estimado foi de 72,5 cm e para os machos foi de 72,0 cm, o (L100) é maior nas fêmeas com 106 cm, para machos com 94,5 cm. As fêmeas foram mais numerosas nas classes de comprimento entre 63,0 cm a 81,0 cm, os machos nas classes de comprimento 58,0 cm a 78,0 cm. A proporção sexual se apresentou da seguinte maneira: entre os meses de outubro de 2007 a março de 2008, a proporção foi de 1 macho para 3 fêmeas e nos meses de novembro a dezembro de 2008 foi de 1 macho para 17 fêmeas. Os valores médios estimados do fator de condição (K) em função do regime hídrico,foram maiores entre os machos na enchente de 2008 e cheia de 2009, as femeas apresentaram valores equilibrados, a condição apresentada pelos indivíduos durante o período de estudo não variou significativamente em função do regime hídrico.Dentre os fatores abióticos analisados, a precipitação pluviométrica contribuindo indiretamente na reprodução de P. punctinfer. A sazonalidade, caracterizada pelas fases do regime hídrico na região, influenciou na maior oferta de itens para a dieta, principalmente na cheia. Apesar da grande contribuição de peixes na dieta de P.punctifer, a diversidade de itens alimentares indica uma dieta carnívora generalista, pois não apresenta seletividade sobre as presas incluindo diversas famílias de peixes e outros grupos alimentares. A presença de vertebrados terrestres neste trabalho pode indicar um hábito oportunista da espécie.

Trophic downgrading of ecosystems necessitates a functional understanding of trophic cascades. Identifying the presence of cascades, and the mechanisms through which they occur, is particularly important for seagrass meadows, which are among the most threatened ecosystems on Earth. Shark Bay, Western Australia provides a model system to investigate the potential importance of top-down effects in a relatively pristine seagrass ecosystem. The role of megagrazers in the Shark Bay system has been previously investigated, but the role of macrograzers (i.e., teleosts), and their importance relative to megagrazers, remains unknown. The objective of my dissertation was to elucidate the importance of teleost macrograzers in transmitting top-down effects in seagrass ecosystems. Seagrasses and macroalgae were the main food of the abundant teleost Pelates octolineatus, but stable isotopic values suggested that algae may contribute a larger portion of assimilated food than suggested by gut contents. Pelates octolineatus is at risk from numerous predators, with pied cormorants (Phalacrocorax varius) taking the majority of tethered P. octolineatus. Using a combination of fish trapping and unbaited underwater video surveillance, I found that the relative abundance of P. octolineatus was greater in interior areas of seagrass banks during the cold season, and that the mean length of P. octolineatus was greater in these areas compared to along edges of banks. Finally, I used seagrass transplants and exclosure experiments to determine the relative effect of megagrazers and macrograzers on the establishment and persistence of three species of seagrasses in interior microhabitats. Teleost grazing had the largest impact on seagrass species with the highest nutrient content, and these impacts were primarily observed during the warm season. My findings are consistent with predictions of a behaviorally-mediated trophic cascade initiated by tiger sharks (Galeocerdo cuvier) and transmitted through herbivorous fishes and their predators.