Doctor of Philosophy / Department of Biology / Keith B. Gido / Habitat fragmentation and loss threaten global biodiversity, but organism responses to changing habitat availability are mediated by structural properties of their habitats. In particular, organisms inhabiting dendritic landscapes with hierarchically arranged branches of habitat tend to have limited access to some patches even in the absence of fragmentation. Consequently, organisms inhabiting dendritic landscapes such as streams respond strongly to fragmentation. Using a combination of meta-analysis, field observations, and ecological network modeling I show that stream fishes respond to fragmentation in predictable ways. First, I addressed how dams and stream dewatering have created a mosaic of large river fragments throughout the Great Plains. Using a geographic information system and literature accounts of population status (i.e., stable, declining, extirpated) for eight “pelagic-spawning” fishes, I found stream fragment length predicted population status (ANOVA, F2,21 = 30.14, P < 0.01) and explained 71% of reported extirpations. In a second study, I applied a new measure of habitat connectivity (the Dendritic Connectivity Index; DCI) to 12 stream networks in Kansas to test the DCI as a predictor of fish response to fragmentation by road crossings. Results indicated fish communities in stream segments isolated by road crossings had reduced species richness (alpha diversity) and greater dissimilarity (beta diversity) to segments that maintained connectivity with the network, and the DCI predicted patterns in community similarity among networks (n = 12; F1,10 = 19.05, r2 = 0.66, P < 0.01). Finally, I modeled fish distributions in theoretical riverscapes to test for mechanistic linkages between fragmentation and local extirpations. Results suggested the number of small fragments predicted declines in patch occupancy, and the magnitude of change in occupancy varied with dispersal ability (“high” dispersers responded more strongly than “low” dispersers). Taken together, these works show context-dependencies in fish responses to fragmentation, but a unifying theme is that small fragments contribute to attenuated biodiversity. Moreover, the predictable manner in which stream fish react to fragmentation will aid in biodiversity conservation by revealing potential responses to future scenarios regarding changes to habitat connectivity.

The goal of this research was to develop statistically robust ecosystem-based approaches, while optimizing data acquisition on relatively unexploited fish species in South Florida reefs, i.e., parrotfishes, Family Scaridae, in Biscayne Bay (with seasonal roller frame beam trawl surveys, 1996-2000) and Florida Keys (with annual Reef Fish Visual Censuses, 1997-2001), by following these steps: (I) analysis of information gaps for the stocks, including systematics, biogeography, population dynamics, reproductive ecology, trophodynamics, habitat use, and fisheries dynamics of Western Atlantic parrotfishes; (II) determination of primary research objectives from prioritization in Step I; (III) determination of essential fish habitats, ontogenetic shifts, migrations, and reef-seagrass habitat, from integration of stratified sampling design for fisheries-independent surveys, habitat selection theory-based analyses, and length-based analyses; (IV) estimation of population dynamics and fisheries-specific parameters encompassing life history demographics from empirical data or comparisons to theoretical expectations adapted to local conditions; (V) simulation modeling of a realistic range of fishing scenarios and demographic characteristics to evaluate the efficacy of potential traditional fisheries and spatial management strategies; and (VI) application of sampling optimization procedures and fisheries ecology approaches. Four scarid species had an estimated combined abundance of ca. 36.8 x 106 individuals in the Florida Keys. Connectivity among seagrass beds, coral reefs and deep waters had three major patterns: seagrass dwellers, reef dwellers, with inshore-to-offshore ontogenetic , and a seagrass-reef connection, using Biscayne Bay as an important recruitment ground. Marine protected areas of the Florida Keys National Marine Sanctuary did not show effects on abundance, size composition or spatial distribution of any parrotfish studied. Simulations suggested relatively short longevities (5-10 years), moderate body growth curvature, high instantaneous natural mortality rates (0.3-0.6 y super minus one), and low annual survival rates (27-54%). Simulated estimates of fishing mortalities ranged from 0.3 to 0.6 y super minus one, indicating low levels of exploitation, but low Spawning Potential Ratios (SPR = 23.5-26%). Proposed potential exploitation based on a legal minimum size equal to their size at first maturity and fishing rates equal or below to their natural mortality should secure SPR values at 45-48%.

Os peixes podem migrar até milhares de quilômetros, buscando completar seu ciclo de vida. A migração de peixes presta importantes serviços aos ecossistemas aquáticos, como: dispersão de sementes, ciclagem de nutrientes e transferência de energia entre ambientes com alta produtividade e ambientes com baixa produtividade, exercendo assim papel fundamental nas redes tróficas de rios tropicais. Os ecossistemas aquáticos tropicais estão situados geralmente em países em desenvolvimento, que passam por rápida industrialização e aonde uma das principais fontes de energia elétrica vem da construção de usinas hidrelétricas, implicando no barramento e fragmentação do habitat de peixes migratórios. Por isso, os peixes migratórios estão sujeitos não somente aos impactos da pesca, mas também a degradação e a perda de conectividade entre os habitats utilizados. Países tropicais possuem pouco conhecimento ecológico sobre a migração de peixes, dificultando a aplicação de políticas de manejo e conservação. Por outro lado, pescadores artesanais possuem conhecimento detalhado sobre a ecologia dos peixes que pescam, sendo que esse conhecimento local pode servir como base para políticas de manejo pesqueiro e conservação. O objetivo deste trabalho é avaliar o conhecimento ecológico de pescadores sobre a migração de peixes ao longo de um rio tropical, o Rio Tapajós, um dos principais afluentes do Rio Amazonas, no Brasil. Ao todo, 273 pescadores foram entrevistados individualmente utilizando-se de questionários padronizados, ao longo de quatro trechos de rio: Baixo (entre Santarém e Belterra), Baixo-médio (entre Belterra e Aveiros), Médio (Itaituba) e Alto Tapajós (Jacareacanga). Neste estudo são analisadas e discutidas algumas hipóteses sobre a migração e movimentação de quatro espécies de peixes reconhecidamente migratórios: Filhote ou Piraíba (Brachyplatystoma filamentosum) Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) e Matrinxã (Brycon spp.), além de três peixes não considerados como sendo migratórios: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) e Caratinga (Geophagus surinamensis). Segundo a maioria dos pescadores entrevistados, o Filhote migra rio acima e apresenta tamanhos maiores em trechos superiores (médio e alto) do rio, uma evidência de que a espécie utiliza estes habitats rio acima para desova. O Jaraqui e a Matrinxã apresentam padrões similares segundo os pescadores: migração longitudinal seguida de migração lateral. Entretanto, os pescadores mencionaram que Jaraqui, o peixe mais capturado em todos os trechos do rio dentre os peixes estudados, realiza migração a jusante durante a seca nos trechos Baixo e Baixo-médio Tapajós, indicando que a espécie retorna ao Rio Amazonas, provavelmente para desovar, diferentemente dos trechos Médio e Alto Tapajós onde não é citada migração a jusante, levantando a hipótese de que sejam populações com padrões migratórios distintos. O Mapará não foi citado no trecho superior do rio (Alto) e a migração lateral foi o principal movimento indicado pelos pescadores nos demais trechos ao longo do rio. Os resultados deste estudo têm implicações importantes para a conservação dos peixes. A construção de barragens vi nos trechos superiores do Rio Tapajós representa uma ameaça aos peixes migradores estudados, como o Filhote, o Jaraqui e a Matrinxã. Portanto é fundamental que estas informações sejam consideradas no planejamento energético e desenvolvimento da Amazônia. Recomenda-se investigar mais sobre a migração dos peixes no Rio Tapajós, para se discutir futuras estratégias de manejo e conversação. / Fish can migrate up to thousands of kilometers, seeking to complete their life cycle. The migration of fish provides important services to aquatic ecosystems, such as seed dispersal, nutrient cycling and energy transfer between high-productivity environments and low-productivity environments, thus playing a key role in the food webs of tropical rivers. Tropical aquatic ecosystems are often located in developing countries that undergo rapid industrialization and where a major source of electricity comes from the construction of hydroelectric power plants, which results in the impounding and fragmentation of habitat for migratory fish. Therefore, migratory fish are subject not only to the impacts of fishing, but also to the degradation and loss of connectivity between the habitats used. Tropical countries have little ecological knowledge about fish migration, hampering the implementation of management and conservation policies. On the other hand, artisanal fishermen have detailed knowledge about the ecology of fishes they catch, and such local knowledge can be used as the basis for fisheries management and conservation policies. The objective of this study is to assess the ecological knowledge of fishermen on fish migration along a tropical river, the Tapajós River, a major affluent of the Amazon River, in Brazil. Altogether, 273 fishermen were interviewed individually using a structured questionnaire along four stretches of the river: Low (between Santarém and Belterra), Low-medium (between Belterra and Aveiros), Medium (Itaituba) and Upper Tapajós (Jacareacanga). This study analyzed and discussed some hypotheses about the migration and movement of four known species of migratory fish: Filhote or Piraíba (Brachyplatystoma filamentosum), Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) and Matrinxã (Brycon spp.), as well as three species of fish considered as non-migratory: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) and Caratinga (Geophagus surinamensis). According to most fishermen, Filhote migrates upstream and features larger sizes in the upper parts of the river (Medium and Upper Tapajós), an evidence that the species use these habitats upstream for spawning. The Jaraqui and Matrinxã have similar patterns according to the fishermen: longitudinal migration followed by vii lateral migration. However, the fishermen mentioned that Jaraqui, which is the fish most commonly caught among the fish studied along the river stretches, performs downstream migration during the draughts in Low and Low-Medium Tapajós, indicating that the species returns to the Amazon River, presumably to spawn, differently from the Medium and Upper Tapajós stretches, where downstream migration is not mentioned, raising the possibility that these are populations with distinct migration patterns. The Mapará was not mentioned in the upper part of the river (Upper) and the lateral migration was the main movement indicated by fishermen in the other stretches along the river. The results of this study have important implications for the fish conservation. The construction of dams in the upper parts of the Tapajós River is a threat to the migratory fish studied, such as the Filhote, the Jaraqui and the Matrinxã. Therefore, it is essential that the aforementioned information be considered in energy planning and development of the Amazon. It is recommended to further investigate the migration of fish in the Tapajós River in order to discuss future management and conversation strategies.

Os peixes podem migrar até milhares de quilômetros, buscando completar seu ciclo de vida. A migração de peixes presta importantes serviços aos ecossistemas aquáticos, como: dispersão de sementes, ciclagem de nutrientes e transferência de energia entre ambientes com alta produtividade e ambientes com baixa produtividade, exercendo assim papel fundamental nas redes tróficas de rios tropicais. Os ecossistemas aquáticos tropicais estão situados geralmente em países em desenvolvimento, que passam por rápida industrialização e aonde uma das principais fontes de energia elétrica vem da construção de usinas hidrelétricas, implicando no barramento e fragmentação do habitat de peixes migratórios. Por isso, os peixes migratórios estão sujeitos não somente aos impactos da pesca, mas também a degradação e a perda de conectividade entre os habitats utilizados. Países tropicais possuem pouco conhecimento ecológico sobre a migração de peixes, dificultando a aplicação de políticas de manejo e conservação. Por outro lado, pescadores artesanais possuem conhecimento detalhado sobre a ecologia dos peixes que pescam, sendo que esse conhecimento local pode servir como base para políticas de manejo pesqueiro e conservação. O objetivo deste trabalho é avaliar o conhecimento ecológico de pescadores sobre a migração de peixes ao longo de um rio tropical, o Rio Tapajós, um dos principais afluentes do Rio Amazonas, no Brasil. Ao todo, 273 pescadores foram entrevistados individualmente utilizando-se de questionários padronizados, ao longo de quatro trechos de rio: Baixo (entre Santarém e Belterra), Baixo-médio (entre Belterra e Aveiros), Médio (Itaituba) e Alto Tapajós (Jacareacanga). Neste estudo são analisadas e discutidas algumas hipóteses sobre a migração e movimentação de quatro espécies de peixes reconhecidamente migratórios: Filhote ou Piraíba (Brachyplatystoma filamentosum) Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) e Matrinxã (Brycon spp.), além de três peixes não considerados como sendo migratórios: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) e Caratinga (Geophagus surinamensis). Segundo a maioria dos pescadores entrevistados, o Filhote migra rio acima e apresenta tamanhos maiores em trechos superiores (médio e alto) do rio, uma evidência de que a espécie utiliza estes habitats rio acima para desova. O Jaraqui e a Matrinxã apresentam padrões similares segundo os pescadores: migração longitudinal seguida de migração lateral. Entretanto, os pescadores mencionaram que Jaraqui, o peixe mais capturado em todos os trechos do rio dentre os peixes estudados, realiza migração a jusante durante a seca nos trechos Baixo e Baixo-médio Tapajós, indicando que a espécie retorna ao Rio Amazonas, provavelmente para desovar, diferentemente dos trechos Médio e Alto Tapajós onde não é citada migração a jusante, levantando a hipótese de que sejam populações com padrões migratórios distintos. O Mapará não foi citado no trecho superior do rio (Alto) e a migração lateral foi o principal movimento indicado pelos pescadores nos demais trechos ao longo do rio. Os resultados deste estudo têm implicações importantes para a conservação dos peixes. A construção de barragens vi nos trechos superiores do Rio Tapajós representa uma ameaça aos peixes migradores estudados, como o Filhote, o Jaraqui e a Matrinxã. Portanto é fundamental que estas informações sejam consideradas no planejamento energético e desenvolvimento da Amazônia. Recomenda-se investigar mais sobre a migração dos peixes no Rio Tapajós, para se discutir futuras estratégias de manejo e conversação. / Fish can migrate up to thousands of kilometers, seeking to complete their life cycle. The migration of fish provides important services to aquatic ecosystems, such as seed dispersal, nutrient cycling and energy transfer between high-productivity environments and low-productivity environments, thus playing a key role in the food webs of tropical rivers. Tropical aquatic ecosystems are often located in developing countries that undergo rapid industrialization and where a major source of electricity comes from the construction of hydroelectric power plants, which results in the impounding and fragmentation of habitat for migratory fish. Therefore, migratory fish are subject not only to the impacts of fishing, but also to the degradation and loss of connectivity between the habitats used. Tropical countries have little ecological knowledge about fish migration, hampering the implementation of management and conservation policies. On the other hand, artisanal fishermen have detailed knowledge about the ecology of fishes they catch, and such local knowledge can be used as the basis for fisheries management and conservation policies. The objective of this study is to assess the ecological knowledge of fishermen on fish migration along a tropical river, the Tapajós River, a major affluent of the Amazon River, in Brazil. Altogether, 273 fishermen were interviewed individually using a structured questionnaire along four stretches of the river: Low (between Santarém and Belterra), Low-medium (between Belterra and Aveiros), Medium (Itaituba) and Upper Tapajós (Jacareacanga). This study analyzed and discussed some hypotheses about the migration and movement of four known species of migratory fish: Filhote or Piraíba (Brachyplatystoma filamentosum), Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) and Matrinxã (Brycon spp.), as well as three species of fish considered as non-migratory: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) and Caratinga (Geophagus surinamensis). According to most fishermen, Filhote migrates upstream and features larger sizes in the upper parts of the river (Medium and Upper Tapajós), an evidence that the species use these habitats upstream for spawning. The Jaraqui and Matrinxã have similar patterns according to the fishermen: longitudinal migration followed by vii lateral migration. However, the fishermen mentioned that Jaraqui, which is the fish most commonly caught among the fish studied along the river stretches, performs downstream migration during the draughts in Low and Low-Medium Tapajós, indicating that the species returns to the Amazon River, presumably to spawn, differently from the Medium and Upper Tapajós stretches, where downstream migration is not mentioned, raising the possibility that these are populations with distinct migration patterns. The Mapará was not mentioned in the upper part of the river (Upper) and the lateral migration was the main movement indicated by fishermen in the other stretches along the river. The results of this study have important implications for the fish conservation. The construction of dams in the upper parts of the Tapajós River is a threat to the migratory fish studied, such as the Filhote, the Jaraqui and the Matrinxã. Therefore, it is essential that the aforementioned information be considered in energy planning and development of the Amazon. It is recommended to further investigate the migration of fish in the Tapajós River in order to discuss future management and conversation strategies.

Os peixes podem migrar até milhares de quilômetros, buscando completar seu ciclo de vida. A migração de peixes presta importantes serviços aos ecossistemas aquáticos, como: dispersão de sementes, ciclagem de nutrientes e transferência de energia entre ambientes com alta produtividade e ambientes com baixa produtividade, exercendo assim papel fundamental nas redes tróficas de rios tropicais. Os ecossistemas aquáticos tropicais estão situados geralmente em países em desenvolvimento, que passam por rápida industrialização e aonde uma das principais fontes de energia elétrica vem da construção de usinas hidrelétricas, implicando no barramento e fragmentação do habitat de peixes migratórios. Por isso, os peixes migratórios estão sujeitos não somente aos impactos da pesca, mas também a degradação e a perda de conectividade entre os habitats utilizados. Países tropicais possuem pouco conhecimento ecológico sobre a migração de peixes, dificultando a aplicação de políticas de manejo e conservação. Por outro lado, pescadores artesanais possuem conhecimento detalhado sobre a ecologia dos peixes que pescam, sendo que esse conhecimento local pode servir como base para políticas de manejo pesqueiro e conservação. O objetivo deste trabalho é avaliar o conhecimento ecológico de pescadores sobre a migração de peixes ao longo de um rio tropical, o Rio Tapajós, um dos principais afluentes do Rio Amazonas, no Brasil. Ao todo, 273 pescadores foram entrevistados individualmente utilizando-se de questionários padronizados, ao longo de quatro trechos de rio: Baixo (entre Santarém e Belterra), Baixo-médio (entre Belterra e Aveiros), Médio (Itaituba) e Alto Tapajós (Jacareacanga). Neste estudo são analisadas e discutidas algumas hipóteses sobre a migração e movimentação de quatro espécies de peixes reconhecidamente migratórios: Filhote ou Piraíba (Brachyplatystoma filamentosum) Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) e Matrinxã (Brycon spp.), além de três peixes não considerados como sendo migratórios: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) e Caratinga (Geophagus surinamensis). Segundo a maioria dos pescadores entrevistados, o Filhote migra rio acima e apresenta tamanhos maiores em trechos superiores (médio e alto) do rio, uma evidência de que a espécie utiliza estes habitats rio acima para desova. O Jaraqui e a Matrinxã apresentam padrões similares segundo os pescadores: migração longitudinal seguida de migração lateral. Entretanto, os pescadores mencionaram que Jaraqui, o peixe mais capturado em todos os trechos do rio dentre os peixes estudados, realiza migração a jusante durante a seca nos trechos Baixo e Baixo-médio Tapajós, indicando que a espécie retorna ao Rio Amazonas, provavelmente para desovar, diferentemente dos trechos Médio e Alto Tapajós onde não é citada migração a jusante, levantando a hipótese de que sejam populações com padrões migratórios distintos. O Mapará não foi citado no trecho superior do rio (Alto) e a migração lateral foi o principal movimento indicado pelos pescadores nos demais trechos ao longo do rio. Os resultados deste estudo têm implicações importantes para a conservação dos peixes. A construção de barragens vi nos trechos superiores do Rio Tapajós representa uma ameaça aos peixes migradores estudados, como o Filhote, o Jaraqui e a Matrinxã. Portanto é fundamental que estas informações sejam consideradas no planejamento energético e desenvolvimento da Amazônia. Recomenda-se investigar mais sobre a migração dos peixes no Rio Tapajós, para se discutir futuras estratégias de manejo e conversação. / Fish can migrate up to thousands of kilometers, seeking to complete their life cycle. The migration of fish provides important services to aquatic ecosystems, such as seed dispersal, nutrient cycling and energy transfer between high-productivity environments and low-productivity environments, thus playing a key role in the food webs of tropical rivers. Tropical aquatic ecosystems are often located in developing countries that undergo rapid industrialization and where a major source of electricity comes from the construction of hydroelectric power plants, which results in the impounding and fragmentation of habitat for migratory fish. Therefore, migratory fish are subject not only to the impacts of fishing, but also to the degradation and loss of connectivity between the habitats used. Tropical countries have little ecological knowledge about fish migration, hampering the implementation of management and conservation policies. On the other hand, artisanal fishermen have detailed knowledge about the ecology of fishes they catch, and such local knowledge can be used as the basis for fisheries management and conservation policies. The objective of this study is to assess the ecological knowledge of fishermen on fish migration along a tropical river, the Tapajós River, a major affluent of the Amazon River, in Brazil. Altogether, 273 fishermen were interviewed individually using a structured questionnaire along four stretches of the river: Low (between Santarém and Belterra), Low-medium (between Belterra and Aveiros), Medium (Itaituba) and Upper Tapajós (Jacareacanga). This study analyzed and discussed some hypotheses about the migration and movement of four known species of migratory fish: Filhote or Piraíba (Brachyplatystoma filamentosum), Mapará (Hypophthalmus marginatus), Jaraqui (Semaprochilodus spp.) and Matrinxã (Brycon spp.), as well as three species of fish considered as non-migratory: Tucunaré (Cichla spp.), Pescada (Plagioscium squamosissimus) and Caratinga (Geophagus surinamensis). According to most fishermen, Filhote migrates upstream and features larger sizes in the upper parts of the river (Medium and Upper Tapajós), an evidence that the species use these habitats upstream for spawning. The Jaraqui and Matrinxã have similar patterns according to the fishermen: longitudinal migration followed by vii lateral migration. However, the fishermen mentioned that Jaraqui, which is the fish most commonly caught among the fish studied along the river stretches, performs downstream migration during the draughts in Low and Low-Medium Tapajós, indicating that the species returns to the Amazon River, presumably to spawn, differently from the Medium and Upper Tapajós stretches, where downstream migration is not mentioned, raising the possibility that these are populations with distinct migration patterns. The Mapará was not mentioned in the upper part of the river (Upper) and the lateral migration was the main movement indicated by fishermen in the other stretches along the river. The results of this study have important implications for the fish conservation. The construction of dams in the upper parts of the Tapajós River is a threat to the migratory fish studied, such as the Filhote, the Jaraqui and the Matrinxã. Therefore, it is essential that the aforementioned information be considered in energy planning and development of the Amazon. It is recommended to further investigate the migration of fish in the Tapajós River in order to discuss future management and conversation strategies.

Orientador: Ivan Sazima / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T13:26:05Z (GMT). No. of bitstreams: 1 Krajewski_JoaoPaulo_M.pdf: 1155075 bytes, checksum: 09dd9581d8d018e04f1c81a73d7f26fd (MD5) Previous issue date: 2005 / Resumo: A família Mullidae (Perciformes) inclui cerca de 50 espécies de peixes distribuídas em áreas tropicais e subtropicais dos Oceanos Índico, Pacífico e Atlântico. Os mulídeos forrageiam no substrato, orientados principalmente por um par de barbilhões. Foi aqui estudada, comparativamente, a atividade de forrageamento e o comportamento alimentar de Mulloidichthys martinicus e Pseudupeneus maculatus, que vivem em sintopia no Arquipélago de Fernando de Noronha (Pernambuco). Foi também registrado o comportamento de forrageamento de grupos de P. maculatus na Reserva Biológica Marinha do Arvoredo (Santa Catarina) e a formação de cardumes mistos sem atividade alimentar por M. martinicus em Fernando de Noronha. As duas espécies diferiram em todos os aspectos analisados. Pseudupeneus maculatus forrageia sobre três tipos de substrato, preferindo substrato misto composto por areia e algas. Mulloidichthys martinicus explora dois tipos de substrato, preferindo substrato arenoso. Pseudupeneus maculatus apresenta menor freqüência alimentar, percorrendo menor distância por tempo durante o forrageamento e apresenta repertório comportamental diversificado ao forragear. Adicionalmente, foram registrados indivíduos de P. maculatus alimentando-se de plâncton na coluna d¿água quando forrageando em grupos, o primeiro registro de planctofagia para a espécie. Foi também estudado um possível caso de mimetismo de proteção entre M. martinicus e Haemulon chrysargyreum (Haemulidae), que freqüentemente formam cardumes mistos em Fernando de Noronha. Pseudupeneus maculatus é aqui caracterizada como mais versátil, na seleção de substrato para forrageio e em seu comportamento alimentar, quando comparada a M. martinicus. Apesar de apresentarem diversas características em comum, as espécies de Mullidae geralmente diferem em sua atividade de forrageamento, indicando que sua simples caracterização como fossadores generalizados de substratos não consolidados é inadequada / Abstract: The goatfishes (Mullidae), include about 50 species distributed in tropical and subtropical Indo-Pacific e Atlantic Oceans. All goatfishes forage on the bottom, primarily oriented by a pair of chemosensorial barbels. The foraging behaviour and activity of Mulloidichthys martinicus e Pseudupeneus maculatus was studied comparatively at Fernando de Noronha Archipelago two goatfishes syntopic in (Brazil, Pernambuco), where these two species are syntopic. The behaviour of P. maculatus when foraging in groups at the Reserva Biológica Marinha do Arvoredo (Brazil, Santa Catarina) and mixed schooling behaviour of M. martinicus at Fernando de Noronha was also studied. The two species differed in all analyzed aspects. Pseudupeneus maculatus forages over tree substrate types but prefers mixed substrate composed of sand and algae. Mulloidichthys martinicus forages over two substrate types, preferring sandy substrate. Pseudupeneus maculatus has a lower feeding rate, roams less per given time and displays a more diverse feeding mode repertoire when compared with M. martinicus. Moreover, a study of plankton-feeding behaviour by P. maculatus when foraging in groups at Fernando de Noronha and the Reserva Biológica Marinha do Arvoredo was made, the first record of plankton-feeding for P. maculatus. A presumed example of protective mimicry by M. martinicus and Haemulon chrysargyreum (Haemulidae), which frequently form mixed schools in Fernando de Noronha, was also studied. Pseudupeneus maculatus is here considered as a more versatile bottom forager when compared to M. martinicus. Notwithstanding the overall similarity between mullid species, they do differ in their substrate preferences and foraging activity, which indicates that goatfishes can not be characterized simply as generalized soft bottom foragers / Mestrado / Ecologia / Mestre em Ecologia

Thesis (M. Sc. (Agriculture)) -- University of Limpopo, 2016 / Fish assemblages in relation to environmental variables within the Broederstroom and Debengeni Rivers were investigated. Both rivers were characterized by coarse substrates (pebble and gravel), temperatures below 20°C and moderate depth. Trout dominated fish assemblages in terms of numbers caught and was only distributed at higher altitude sites >1400 m (a.s.l). Coarse substrates, temperatures below 15°C, flow rate, depth and riparian cover were the variables shown important for the distribution of trout by multivariate analysis. The confinement of the trout to higher altitude and lack of optimal habitat variables at lower altitude sites contributed to the assertion that the area is marginal for trout distribution. It was therefore inferred that the marginality of the area is the possible explanation for trout failure to self-sustain its population, therefore dependent on the continuous restocks by the local hatchery. The continuous restocks of small size trout in the Broederstroom River prompted a subsequent study where trout’s impact on macroinvertebrate communities was evaluated through surveys and field experiments. The ability of small trout to utilize macroinvertebrates made them suitable candidates to evaluating their impact in the area. Aquatic invertebrates were found to be the main food source for the trout in the area. Taxa such as Gomphidae and Potamonautidae were the most frequent food items from the analyzed stomachs of trout. However, observations from both field surveys and experiments showed that trout is a weak regulator of macroinvertebrate diversity in the area, since there were no significant differences (ANOVA, P<0.05) in the diversity of invertebrates from trout invaded and uninvaded sites. Trout being a weak regulator of macroinvertebrate diversity in the area, it prompted surveys to the Ebenezer Dam to determine its competitive interactions with native predatory species. If the introduced species is a more efficient predator than the native predator species, it may affect changes in the structure of the habitat and food resource. Trout in the Ebenezer Dam was found to be selective to habitat variables whilst C. gariepinus was cosmopolitan to all habitat categories. The catfish also had a broader food preference than trout and the diversity of the food items was significantly different (ANOVA, P<0.05) between the two species. Unfortunately, the interspecific food overlap between trout and the catfish could not be determined in Ebenezer Dam, because of the small sample size of trout but food selection between vii them was evident. It was then concluded that the native catfish has a wider niche and it is a more efficient predator than the introduced trout. This observation contributed further to the assertion that the area is marginal for trout to thrive. Due to trout selection of habitat variables, it became prudent to carry out another study where the past climate and land use changes were analyzed to determine their effect on the habitat that could have affected the distribution of trout in the area. Future projections were also made to determine possible future impacts of climate change on the distribution of trout in the area. The effects of climate and land use change resulted in warmer water temperature, altered riparian cover and altered stream flow patterns. The changes could have influenced the confinement of trout to higher altitude catchments. The projected maximum temperatures by 2050 shows an increase from 2014 with a decline in precipitation. If these projections are to be the same for water temperature and flow regimes, coupled with current land uses in the area, they will continue to affect the distribution of trout negatively.

The Arctic is warming faster than any other region of the globe. To conserve and manage many thousands of lakes across arctic landscapes, scientists need to understand historic and present conditions within these lakes to predict how the lakes, and the organisms that inhabit them, may respond to a changing climate. The goal of my research was to improve our understanding of what physical, chemical, and biological factors contribute to: 1) how lake food webs are assembled; and, 2) how these food webs may change in the future. First, I used long-term observations and lab experiments to determine how fish food, including zooplankton and snails, may respond to a warming climate. I then used field measurements of arctic char (Salvelinus alpinus) body characteristics, genetic samples, and fish diets to investigate if, and potentially why, populations of arctic char across a series of lakes achieve different maximum body sizes. Finally, as a method of monitoring population-level changes of fish abundance, I collected samples of arctic char DNA in lake water to test if estimated arctic char population abundances within a given lake correspond to the amount of DNA collected. Fish will require more food to eat as their metabolism increases with warming lake temperatures. Based on a thirty-year period of record, I determined zooplankton abundance increases in warmer years, indicating there is likely to be enough food for fishes in the future. Accordingly, zooplankton and snail abundance and development was also faster in warmer treatments of my lab experiments. My field observations indicated these are important prey items for arctic char. Small arctic char eat more zooplankton and large arctic char eat more snails, and these observations were consistent whether or not other predators are found in the particular lake. Similarly, my analyses did not indicate morphological or genetic differences between small and large arctic char within the same lake, suggesting arctic char size structure is determine by biological characteristics, including primary productivity and arctic char density. Indeed, estimates of arctic char population abundances across a series of lakes followed a gradient of arctic char densities, and my DNA sampling corresponded with this gradient. As there are thousands of lakes across the Arctic, my research demonstrates lake food webs, and the fishes within them, are likely to adapt to a warming climate. However, biological, chemical, and physical properties of these lakes can vary widely such that management and conservation plans may need to be developed at relatively small spatial scales across a large landscape.

No description available.

Populations of anadromous brook trout can be found from northern Canada into New England. It is believed that the extent of anadromy exhibited by coastal brook trout populations decreases with latitude, but the ecology and movements of the more southern populations are less studied. A 33-month acoustic telemetry study of anadromous brook trout (Salvelinus fontinalis) was conducted in a restored coastal stream and adjacent marine system in southeastern Massachusetts. Movement and migration patterns of 54 brook trout were investigated for individual differences and common features. Individuals exhibited a range of movement patterns. Some were more resident and only moved short distances, while others moved great distances covering the entire stretch of the stream (7.25 km) and moving into the marine environment. General Additive Mixed Models revealed that date was the major influence on brook trout movement between habitats and predicted peaks in movement in the spring and fall. Downstream movement peaked in the spring and in the fall, suggesting post-spawning feeding migration. Fish transitioned between habitats more often at new and full moons and when stream temperature was between 8 and 12 °C. Upstream transitions peaked as temperatures declined in winter 2011. Fifty percent of tagged brook trout were detected in the estuary during the study, suggesting that it is an important habitat for the population. In summer 2012, 14 tagged brook trout (20% of active tags) resided near one receiver at the head of the tide, which contained a thermal refugium in the form of a cold-water spring seep. Of the 84 tagged brook trout, 9.5% moved to the marine environment. Warm temperatures in saline Buttermilk Bay in the summer and cold temperatures in winter probably discourage some individuals from entering the marine environment. Compared to more northern coastal populations of brook trout, the Red Brook population appears to be less anadromous.