Diante da importância das culturas do milho, soja e cana-de-açúcar no cenário agrícola brasileiro, sendo grandes geradores de divisas, a maior produtividade dessas plantas é ideal para a economia. Tal produtividade, no entanto, é comumente afetada por insetos praga, como é o caso de Spodoptera frugiperda para o milho, Anticarsia gemmatalis para a soja e Diatraea saccharalis na cana de açúcar. Na modernidade, alternativas de controle para esses insetos, como o controle biológico tem sido buscadas, e por meio do presente estudo buscou-se avaliar a preferência de Euborellia annulipes e Harmonia axyridis por essas três pragas. Objetivou-se ainda verificar a ocorrência de canibalismo e predação intraguilda entre os predadores, avaliando também taxas de consumo da presa pelos predadores em diferentes estágios de desenvolvimento. A ocorrência de competição entre eles com relação à presa também foi verificada, a fim de avaliar o potencial de uso desses predadores no controle biológico aplicado. Os estudos foram laboratoriais e permitiram detectar que ambas as espécies são potenciais predadores para as pragas testadas. Não foram observadas claras preferências por presas, apesar de diferentes taxas predatórias terem sido encontradas para cada uma das presas. / Given the importance of corn, soybean and sugarcane crops in Brazilian agriculture as big exchange generators, greater plant productivity of these plants is ideal to national economy. Pest insects, such as Spodoptera frugiperda in corn, Anticarsia gemmatalis in soybean and Diatraea saccharalis in sugarcane commonly affect such productivity. Nowadays, alternative control techniques for these insects, such as biological control, have been sought after, and through the current work, it was aimed to evaluate the preference of Euborellia annulipes and Harmonia axyridis for these three pests. It was also an objective to verify the occurrence of cannibalism and intraguild predation among predators, evaluating consumption rates of the prey insects by the predators in different development stages as well. The occurrence of competition between them in relation to their prey was also verified, to evaluate these predators\'s potential use in applied biological control. These studies were conducted in a lab setting, and allowed detecting that both species are potential predators for the tested pests. No distinct preferences by prey were observed, albeit the existence of differing predation rates being found for each prey.

As relações entre o tamanho dos indivíduos de uma espécie e suas consequências anatômicas, fisiológicas e ecológicas são denominadas relações alométricas. Nesse sentido, diversos trabalhos avaliam a influência do tamanho da fêmea de répteis em características relacionadas à sua reprodução, ao que chamamos de alometria reprodutiva. A variação no tamanho dos indivíduos de uma espécie e do investimento reprodutivo das fêmeas pode ser atribuída, dentre outros fatores, a diferenças na qualidade do alimento consumido. No presente estudo utilizamos medidas dos rastros, do tamanho do corpo, da ninhada e do ovo de tartaruga-verde, Chelonia mydas, para avaliar a influência do tamanho da fêmea no investimento reprodutivo. Realizamos também análise de isótopos estáveis de 13C e 15N de diferentes tecidos das fêmeas para avaliar a influência da dieta (recente e antiga) no seu investimento reprodutivo. Coletamos os dados na Ilha da Trindade, principal área de nidificação da espécie em território brasileiro e situada no Sudoeste Atlântico, há aproximadamente 1140 km da costa central do Brasil. Verificamos que fêmeas de níveis tróficos mais altos, ou seja, que incluem itens alimentares de fonte animal em sua dieta, tendem a ser maiores e a produzirem maior quantidade de ovos. Foram estabelecidas equações para estimar o tamanho da fêmea a partir da largura de seu rastro e equações para estimar o tamanho da ninhada a partir do tamanho da fêmea, métricas que poderiam ajudar no monitoramento do sucesso reprodutivo de C. mydas na Ilha da Trindade / Allometric relationships describe anatomical, physiological and ecological variations according to body size The influence of size of females in reptiles in characteristics related to their reproduction, i.e. reproductive allometry, was evaluated is several papers. Variations in size of individuals of a given species and female\'s investment in reproduction may be attributed, among other factors, to differences in quality of consumed food. In the present study we have used data on turtle\'s track width, body size and clutch size of the green turtle Chelonia mydas to evaluate the influence of female\'s size on reproductive investment. We have also performed 13C and 15N stable isotopes analysis of different body tissues of females to evaluate the influence of diet (recent and past) on reproductive investment. Data were collected in Trindade Island, the main nesting areas of C. mydas in the Brazilian territory, which is situated in the SW Atlantic, 1140 km away from the central coast of Brazil. We have verified that females from higher trophic levels, i.e. the ones including more food from animal origin in their diet, were bigger and produced larger clutches. Equations were build to estimate female\'s size from track width and clutch size from female\'s size. These metrics could help in the monitoring of the reproductive success of C. mydas in Trindade Island

This research focused on population dynamics of two gelatinous zooplankters (Aequorea & Pyrosoma atlanticum) in the northern California Current to assess their relationship to environmental conditions and role in the pelagic ecosystem. Data collected since 1999 showed seasonal and interannual fluctuations in the abundance and distribution of Aequorea in the NCC, with a positive correlation with sea surface temperature and salinity. Pyrosoma atlanticum, which are typically found in tropical waters, have only been observed in high abundances in the NCC since 2014 and their role in the pelagic ecosystem is not well understood. Pyrosome abundance related to in situ environmental variables showed a positive correlation with warmer SST. We also used fatty acids as trophic markers to better understand pyrosome trophic ecology in the NCC. FA biomarkers suggest that pyrosomes have a broad phytoplankton diet, which may indicate an ability to inhabit warmer, lower nutrient zones. / 2020-01-11

Elucidation of habitat and resource use patterns is important for facilitating sustainable management of fisheries. Discrete habitats in large aquatic ecosystems may offer distinct resources and differentially affect performance. Movement of organisms and organic materials links these habitats and potentially leads to spatially complex trophic pathways between basal resources and consumers. Habitat and resource use are commonly explored via two common methods: stable isotopes and morphometric analysis. The first research chapter of this thesis employed both methods to investigate seasonal habitat use of yellow perch <i>Perca flavescens</i>in eastern Lake Michigan and connected waterbodies known as drowned river mouth (DRM) lakes. Landmark-based geometric morphometrics was used to compare shape differences among habitats. Stable isotopes of ambient water, otoliths, and soft tissues were compared to differentiate among habitats. Both methods provided evidence of resident nearshore Lake Michigan fish, resident DRM lake fish occupying the littoral zone, and transient Lake Michigan fish occupying the profundal zone of DRM lakes. The majority of transient Lake Michigan fish moved into the profundal zone of DRM lakes in the fall. These results support previously published genetic data of distinct populations of yellow perch in eastern Lake Michigan and connected waterbodies. The second research chapter of this thesis also employed stable isotopes and morphometric analysis, but to investigate the consistency of resource use of age-0 yellow perch in Saginaw Bay, Lake Huron. These methods served as long-term diet indicators, as compared to short-term stomach contents analysis. Both stable isotopes of soft tissues and morphometric analysis showed spatial consistency in variation among sites. Fish from the two sites closer to the tributary input had higher δ¹⁵N values and more fusiform bodies, while fish from the third site further away from the tributary had lower δ¹⁵N values and were deeper-bodied. This spatial variation supports stomach content analysis of age-0 yellow perch from a previously published study. δ¹³C ratios displayed annual variation, and while inconsistent with stomach content analysis, was consistent with available prey items. The findings from this study suggest that young yellow perch in Saginaw Bay have limited movement and forage in a similar area to where they were collected. Previous studies have found discrepancies among indicators and have cautioned generalization of trophic relationships when only relying on a single metric. Agreement between complementary techniques provided additional support to previously-published genetic results and stomach content data, and thereby helped more fully describe habitat use by yellow perch in these systems.

I compared changes in offshore Lake Ontario major species-group biomass, production and diets before (1987-1991) and after (2001-2005) invasion-induced ecological change. I synthesized the observations into carbon-based mass-balanced food webs linking two pathways of energy flow; the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (autotrophic bacteria-heterotrophic protozoans) and determined how the structure and function of the food web changed between time-periods. I use the food web descriptions to simulate the reestablishment of native deepwater bloater. I developed empirical models describing spatial variation in temperature and applied them to investigate predator temperature distributions, bioenergetic consequences of alewife diet and distribution shifts, and zooplankton productivity. Primary production declined as did the biomass and production of all species-groups except Chinook salmon. Total zooplankton production declined by approximately half with cyclopoid copepod production declining proportionately more. Zooplankton species richness and diversity were unaffected. Alewife adapted to low zooplankton production by consuming more Mysis, increasing their trophic level. The increased prey-size and exploitation of spatial heterogeneity in resource patches and temperature may have allowed alewife to maintain their growth efficiency. The trophic level also increased for smelt, adult sculpin, adult alewife and Chinook salmon. Phytoplankton grazing rates declined and predation pressure increased on Mysis, adult smelt and alewife, and decreased on protozoans. Resource to consumer trophic transfer efficiencies changed; increasing for protozoans, Mysis, Chinook salmon and other salmonines and decreasing for zooplankton, prey-fish and benthos. The changes suggest both bottom-up and top-down influences on food web structure. The direct trophic influences of invasive species on the offshore Lake Ontario food web were minor. Carbon flows to Mysis indicated an important, and changing ecological role for this species and we hypothesize that Mysis may have contributed to Diporeia declines. Simulations suggest that only a small reestablished bloater population, limited by Diporeia production, could be sustained.

I compared changes in offshore Lake Ontario major species-group biomass, production and diets before (1987-1991) and after (2001-2005) invasion-induced ecological change. I synthesized the observations into carbon-based mass-balanced food webs linking two pathways of energy flow; the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (autotrophic bacteria-heterotrophic protozoans) and determined how the structure and function of the food web changed between time-periods. I use the food web descriptions to simulate the reestablishment of native deepwater bloater. I developed empirical models describing spatial variation in temperature and applied them to investigate predator temperature distributions, bioenergetic consequences of alewife diet and distribution shifts, and zooplankton productivity. Primary production declined as did the biomass and production of all species-groups except Chinook salmon. Total zooplankton production declined by approximately half with cyclopoid copepod production declining proportionately more. Zooplankton species richness and diversity were unaffected. Alewife adapted to low zooplankton production by consuming more Mysis, increasing their trophic level. The increased prey-size and exploitation of spatial heterogeneity in resource patches and temperature may have allowed alewife to maintain their growth efficiency. The trophic level also increased for smelt, adult sculpin, adult alewife and Chinook salmon. Phytoplankton grazing rates declined and predation pressure increased on Mysis, adult smelt and alewife, and decreased on protozoans. Resource to consumer trophic transfer efficiencies changed; increasing for protozoans, Mysis, Chinook salmon and other salmonines and decreasing for zooplankton, prey-fish and benthos. The changes suggest both bottom-up and top-down influences on food web structure. The direct trophic influences of invasive species on the offshore Lake Ontario food web were minor. Carbon flows to Mysis indicated an important, and changing ecological role for this species and we hypothesize that Mysis may have contributed to Diporeia declines. Simulations suggest that only a small reestablished bloater population, limited by Diporeia production, could be sustained.

The distribution and abundance of stream fishes are influenced by many factors operating at multiple scales. Understanding how environmental variables influence the structure of stream fish assemblages is important for habitat assessment, stream restoration, and for predicting responses to environmental change. An emerging view in community ecology is that a focus on the functional structure of species assemblages in relation to environmental gradients may reveal more general patterns applicable across geographic regions. In this study, I used functional traits related to the trophic ecology, habitat use, and life-history strategies of fishes to examine the influences of environmental factors on stream fish assemblages. The research was carried out in two large regions: the Río Grijalva basin in southern Mexico and the Brazos and Trinity basins in Central Texas. In both regions, relationships between functional structure of stream fish assemblages and environmental factors at local, landscape, and regional scales were examined. Environmental characteristics at all three scales influenced the functional attributes of assemblages studied here. At the local reach scale, stream size, substrate characteristics, the availability of riffle and pool habitats, and abundance of in-stream cover structures were related to the functional trait composition of fish assemblages in the Río Grijalva Basin and in Central Texas streams. Landscape features most strongly related to functional structure in both regions were the extent of forested area in the watershed and the amount of land developed for urban and agricultural uses. At the regional scale, broad physiographic differences between ecoregions had a large influence on the taxonomic and functional composition of stream fish assemblages in Central Texas. Along the broad-scale longitudinal fluvial gradient of the Grijalva region, pronounced changes in the species composition, functional trait diversity, and trophic structure of fish assemblages were observed.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Entender processos que envolvem a interação entre zona ripária e sistemas aquáticos é de fundamental importância para o estudo da dinâmica trófica em riachos. Os mecanismos atuantes nessa complexa interação são muitos, mas o estudo dos peixes pode facilitar a estruturação deste conhecimento, pois estes são os principais organismos que interagem com a biota aquática. Neste sentido, o presente estudo avalia a influência da cobertura do dossel ripário sobre a dinâmica trófica da espécie de lambari B. microcephalus em duas localidades no córrego Andorinha, Ilha Grande-RJ, através da análise da dieta, seletividade de presas e comportamento alimentar. Os dados obtidos e as análises realizadas sugerem que a espécie possui dieta onívora, muito influenciada pela cobertura de dossel e pouco sucetível a mudanças sazonais. Esta variação na dinâmica trófica é percebida em todos os aspectos observados, sugerindo uma marcada plasticidade que permite o ajuste da alimentação, preferência alimentar e comportamento de forrageio às diferentes condições locais. Este estudo contribui para o reconhecimento do valor da floresta ripária como importante agente estruturador da dinâmica trófica em ambientes aquáticos. / Processes concerning the interaction between riparian zones and aquatic ecosystems are of great importance in the study of the trophic relationships in streams. The mechanisms involved in this interaction are many and the study of fishes may support a better understanding of these processes, once these are the main organisms that interact with the aquatic biota. In this sense, this study aims to evaluate the influence of the riparian canopy on the trophic dynamics of the characin species Bryconamericus microcephalus inhabiting two sites of Andorinha stream in Ilha Grande,-RJ. This investigation encompass the feeding, selectivity and behavioral aspects of the studied species as a pathway to better understand the role of canopy cover in the trophic dynamics of aquatic ecosystems. Our data suggest that the species present an omnivorous feeding habit which is profoundly influenced by the canopy cover and weakly subjected to seasonal changes. This modification is easily recognized in many aspects of the feeding dynamics, suggesting a highly plastic species. This plasticity allow the species to adjust diet, morphology, feeding selectivity and behavior to a changing environment. This study brings to light the value of the riparian forest as an important aspect that influences the tropic dynamics in aquatic ecosystems.

Orientador: Rodrigo Egydio Barreto / Resumo: Processos ecológicos como competição e predação tem o potencial de regular populações, influenciando no funcionamento do ecossistema por intermédio da partição de recursos e perda de espécies. A adição de espécies exóticas em teias tróficas podem alterar esses processos ecológicos e provocar efeitos em cascata. Em um estudo pioneiro, avaliamos por uma perspectiva multidisciplinar, os impactos da introdução de uma espécie de siri asiática na costa oeste do Atlântico. Para isso, aspectos populacionais, ecológicos, fisiológicos e comportamentais foram avaliados em ambiente natural e através de experimentação em laboratório. Nossos resultados revelaram que a espécie de siri invasora Charybdis hellerii está estabelecida na litoral do estado de São Paulo, é um competidor vigoroso, disputando recursos com seis espécies de decápodes nativos, e um predador eficiente, de hábito onívoro, que pode elevar a pressão predatória sobre quatro grupos de presas, três consideradas ‘engenheiros do ecossistema’. As análises comportamental e fisiológica revelaram ainda que a espécie invasora e a nativa Cronius ruber são mais ativas, realizam mais interações comportamentais intra e interespecífica, tendem a dominar a região do entremarés inferior em costões rochosos e que ambas disputam diretamente as mesmas tocas e os mesmos alimentos quando estão no mesmo ambiente. Dessa forma, o aumento populacional da espécie invasora pode elevar a pressão competitiva sobre C. ruber, aumentando também a chance d... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Ecological processes, such as predation and competition, have the potential to regulate populations, influencing the functioning of the ecosystem through resources partition and loss of species. The addition of alien species into food webs may change these ecological processes and cause cascading effects. In a pioneering study, the impact of the introduction of a species of Asian crab on the Atlantic west coast was evaluated by a multidisciplinary perspective. For this, population, ecological, physiological, and behavioral aspects were evaluated in natural environment and in laboratory experimentation. The results revealed that the species of invasive crab Charybdis hellerii is established on the coast of São Paulo State. This species is a vigorous competitor, competing for resources with six decapod native species, and an efficient predator with omnivorous habit, which can raise the predatory pressure on four prey groups, three of them considered 'ecosystem engineers'. Behavioral and physiological analysis also showed that invasive species and native Cronius ruber are more active, performing more intra and interspecific behavioral interactions. These species tend to dominate the region of the lower intertidal on rocky shores and both compete directly for the same burrow and food when they are in the same environment. Thus, the population growth of invasive species may increase the competitive pressure on C. ruber, also increasing the risk of competitive exclusion. If this ex... (Complete abstract click electronic access below) / Doutor