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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Caracterização espaço-temporal da população de boto-cinza, Van Bénéden, 1864 (Cetacea: Delphinidae) na Baía de Benevente, Espírito Santo, e implicações para a conservação

Mamede, Natália dos Santos 10 December 2015 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-16T17:27:13Z No. of bitstreams: 1 nataliadossantosmamede.pdf: 3067068 bytes, checksum: 6aefdd9452c0f7d9137d49c0d6f7a648 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-28T12:11:19Z (GMT) No. of bitstreams: 1 nataliadossantosmamede.pdf: 3067068 bytes, checksum: 6aefdd9452c0f7d9137d49c0d6f7a648 (MD5) / Made available in DSpace on 2016-06-28T12:11:19Z (GMT). No. of bitstreams: 1 nataliadossantosmamede.pdf: 3067068 bytes, checksum: 6aefdd9452c0f7d9137d49c0d6f7a648 (MD5) Previous issue date: 2015-12-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No Brasil a pesquisa com Cetáceos tem se intensificado e uma espécie tem ganhado destaque seja pelo número de estudos quanto pelo status de conservação, o boto-cinza, Sotalia guianensis. Uma população de boto-cinza no sul do estado do Espírito Santo foi escolhida para o presente estudo devido a ausência de estudos prévios. Entre os anos de 2012 e 2014 esforços através de métodos que abranjam uma escala espaço-temporal. No total, 117 saídas de barco foram realizadas (472,4 horas), no período de dezembro de 2011 a novembro de 2014. A aplicação da técnica de foto-identificação possibilitou a identificação de 60 indivíduos. A maior parte dos indivíduos foto-identificados foi fiel a esta área durante este período e em diversos graus de residência. Entre os indivíduos foto-identificados não houve diferença entre os tamanhos das áreas de vida e a partir da sobreposição das áreas de vida destes indivíduos e dos grupos avistados, foi possível identificar que a porção mais ao norte da área amostrada da Baía de Benevente foi a mais utilizada pelos botos. As maiores áreas de vida já relatadas para a espécie foram registradas no presente estudo. A partir do método de marcação-recaptura foi estimada uma abundância de 65 a 80 indivíduos aproximadamente. Grupos de botos-cinza foram avistados em todos os anos e estações, correspondendo a 54,38% dos dias de esforço. Em média, os grupos foram compostos por oito indivíduos, e em sua maioria foi observada a presença de filhotes, assim como ao longo de todos os anos e estações. Sendo a presença de filhotes correlacionada ao aumento do tamanho dos grupos. As observações do comportamento dos grupos avistados identificaram que o estado comportamental mais frequente foi a alimentação, seguido pelo deslocamento, socialização e descanso. A ocorrência e a fidelidade desta população de boto-cinza a Baía de Benevente, assim como assim como a presença de filhotes em todas as estações e do comportamento prevalente ser o de alimentação, são todos indicadores da importância da Baía de Benevente seja como área de alimentação e ou de cria. Neste contexto, o tamanho desta população associado a ameaças antrópicas já identificadas colocam esta população em um estado de atenção para possíveis ações de manejo. / In Brazil, research with cetaceans has been intensified the Guiana dolphin, Sotalia guianensis, has gained distinction because of the increasing number of studies regarding its conservation status. An estuarine dolphin population in the southern state of Espirito Santo was chosen for this study due to lack of previous studies. Between 2012 and 2014 efforts were done by methods covering a spatio-temporal scale. A total of 117 boat trips were made (472.4 hours), from December 2011 to November 2014. The application of photo-identification technique allowed the identification of 60 individuals. Most photo-identified individuals were faithful to this area during this period and in various degrees of residence. Among individuals photo-identified no difference between the sizes of home ranges and from the overlapping areas of life of individuals and sighted groups, it observed that the portion farther north of the sampled area of Benevente Bay was most commonly used by dolphins. The largest home range previously reported for the species were recorded in this study. From the mark-recapture method was estimated 59-80 individuals. Estuarine dolphin groups were sighted in all the years and seasons, corresponding to 54.38% of the effort days. On average, the groups were composed of eight individuals, and mostly we observed the presence of calves, as well as over all the years and seasons. Since the presence of calves were correlated to the increase in size of the groups. The observations of the behavior of the sighted group found that the most common behavioral state was foraging, followed by the displacement, socialization and resting. The occurrence and fidelity of this population of Guiana dolphin in Benevente Bay, as well as the presence of calves in all seasons and prevalent behavior was foraging, all are indicators of the importance of Benevente Bay as an feeding and breeding area. In this context, the size of this population associated with anthropogenic threats already identified puts this population in a state of attention to possible management actions.
182

Identificaçäo morfológica e molecular, biometria, abundância e distribuiçäo geográfica de Biomphalaria spp. (Preston, 1910) (Mollusca, Planorbidae), no município de Juiz de Fora, Minas Gerais

Tibiriçá, Sandra Helena Cerrato 10 April 2006 (has links)
Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-07-26T13:40:04Z No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-08T18:45:05Z (GMT) No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) / Made available in DSpace on 2017-08-08T18:45:05Z (GMT). No. of bitstreams: 1 sandrahelenacarratotibirica.pdf: 2260939 bytes, checksum: e1f49dcf7848afde81dd604c28763e2d (MD5) Previous issue date: 2006-04-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo desse estudo foi avaliar a prevalência, infectividade, biometria, abundância e distribuição geográfica de espécies de Biomphalaria no município de Juiz de Fora, Minas Gerais, no ano de 2004. As coletas foram realizadas para atender a dois propósitos. O primeiro propósito visou identificar e avaliar a infectividade, abundância, biometria e distribuição geográfica das espécies encontradas. Desta forma, ocorreram coletas em 31 localidades sendo seis represas, onze açudes, sete hortas contendo valas de irrigação, cinco lagos, uma lagoa e uma cachoeira. As 124 visitas ao campo foram distribuídas nos quatro ciclos estacionais (cada ponto foi visitado quatro vezes) e 1770 moluscos foram capturados, com padronização do tempo de coleta. O segundo propósito, de alargar a amostra para se avaliar a infectividade, ocorreu no início da estação chuvosa do ano de 2004, e 3494 exemplares de Biomphalaria foram coletados sem padronização do tempo de captura. Os 5.264 espécimes, oriundos de dez localidades, sendo três açudes e sete hortas, predominaram nas regiões leste e norte da mancha urbana. Todas as valas de irrigação investigadas estavam colonizadas por Biomphalaria. Através de técnicas de análise morfológica e molecular, identificaram-se três espécies: B. tenagophila, B. peregrina e B. straminea. Nas dez localidades em que se registrou a presença do molusco do gênero Biomphalaria a distribuição foi a seguinte: B. tenagophila foi prevalente em 60 % dos pontos, e B. peregrina em 20% dos pontos. Constatou-se, pela primeira vez no município, a espécie B. straminea que ocorreu em 20% dos pontos. Nenhum molusco foi encontrado infectado com Schistosoma mansoni, no entanto, exemplares de B. straminea capturados nas coordenadas 21º39’59’’S e 43°25’09’’W, quando submetidos ao teste de suscetibilidade ao S. mansoni apresentaram 25,4% de infectividade. Observou-se forte correlação inversa entre as variáveis abundância de Biomphalaria e pluviosidade local, em todas as espécies estudadas. A temperatura influenciou as populações de Biomphalaria estudadas na faixa das médias inferiores a 15,7°C. Estatisticamente, o estudo das variáveis tamanho e peso revelou que as menores médias biométricas ocorreram em B. peregrina, seguida de B. straminea, e as maiores dimensões corporais foram as de B. tenagophila. Verificou-se forte correlação positiva entre as variáveis peso (massa corpórea) e tamanho (diâmetro da concha), nos exemplares encontrados. Conclui-se que no município de Juiz de Fora ocorrem três espécies de Biomphalaria, sendo duas delas, B. straminea e B. tenagophila, de importância epidemiológica. A pluviosidade e a temperatura interferem na abundância dos espécimes locais. Todas as medidas de peso e tamanho das amostragens de Biomphalaria, em Juiz de Fora, estão abaixo das máximas dimensões referidas na literatura. / The objective of this study was to identify the species of Biomphalaria and evaluate their prevalence, infectivity, biometry, abundance and geographic distribution in the municipality of Juiz de Fora, Minas Gerais, Brazil, in 2004. The samples were collected for two purposes. The first was to identify the infectivity, abundance and geographic distribution of the species found. Therefore, samples were collected in 31 locations: 6 reservoirs, 11 rudimentary holding ponds, 7 irrigation ditches, 5 lakes, 1 ornamental pond and 1 waterfall. The 124 field visits were spaced throughout the four seasons (each point visited four times) and 1,770 snails were captured, with standardized collection intervals. The second purpose, to enlarge the sample to assess infectivity, occurred at the start of the wet season in 2004, and 3,494 exemplars of Biomphalaria were collected, without standardized collection intervals. These specimens were gathered from 10 locations – 3 rudimentary holding ponds and 7 irrigation ditches – predominantly in regions located to the east and north of the main urban sprawl. All told, then, 5,264 specimens were collected. All the irrigation ditches were colonized by Biomphalaria. Through morphological and molecular identification techniques, three species were identified: B. tenagophila, B. peregrina and B. straminea. B. tenagophila was prevalent in 60 % of the points and B. peregrina in 20% of them. This is the first report in the municipality of B. straminea, occurring in 20% of the points. No snails were found infected by Schistosoma mansoni, but snails of the species B. straminea captured at 21º39’59’’S and 43°25’09’’W, when submitted to the susceptibility test to S. mansoni, showed an infection rate of 25.4%. There was a strong inverse correlation between the abundance of Biomphalaria and the local rainfall, in all species studied. Temperature influenced the populations of Biomphalaria studied in the range below 15.7°C. Statistical study of the size and weight variables revealed that the smallest biometric averages occurred in B. peregrina, followed by B. straminea, and the largest body dimensions were those of B. tenagophlia. There was a strong positive correlation between weight (body mass) and size (shell diameter) in the exemplars found. The conclusion is that three species of Biomphalaria occur in the municipality of Juiz de Fora, two of them (B. straminea and B. tenagophila) of epidemiological importance. Rainfall and temperature interfered in the abundance of the local specimens. All the weight and size measures of the Biomphalaria specimens in Juiz de Fora are below the maximum figures referred to in the literature.
183

Coeur d’Alene salamander abundance, distribution, and habitat use in Mount Revelstoke National Park of Canada

Larson, Lisa Irene 05 1900 (has links)
The Coeur d’Alene salamander (Plethodon idahoensis) is a species of special concern throughout its global range, which includes southeastern BC (COSEWIC, Nov 2007), Idaho, and Montana, due to disjunct populations and sensitivity to human disturbance. Within the Interior Cedar-Hemlock forest on Mount Revelstoke, BC, Coeur d’Alene salamanders occur at their highest abundance between 600 m and 800 m. Beyond the Mount Revelstoke National Park boundaries, the low-order stream habitat of this species is subject to disturbance from forestry, mining, road building, road maintenance, and watercourse diversions such as run-of-the-river hydro projects. We conducted nocturnal salamander surveys and assessed habitat characteristics on 12 Sites (750 m² – 1000 m² stream transects) along three streams from June through September 2006. Coeur d’Alene salamanders were detected from 600 m - 1000 m on seven of the 12 study sites. Relative abundance of Coeur d’Alene salamanders ranged from 0.005 ± 0.001 per m² to 0.025 ± 0.005 per m² on six sites below 950 m. Coeur d’Alene salamanders occurred at an average of 0.001 ± 0.001 per m² at 972 m, the only site above 950 m where we detected salamanders. Our capture-mark-recapture efforts of three surveys per month in June and August yielded a very low recapture rate (3.95 %). Coeur d’Alene salamanders are challenging to enumerate due to their vertical distribution within the soil and underlying geological material. Neonate, juvenile, and adult Coeur d’Alene salamanders were observed from June to September and the highest proportion of neonates occurred in June, soon after the salamanders emerged from winter hibernation. Results of a logistic regression analysis of 1-m² plots reflected the importance of fine scale habitat characteristics (quadrat gradient, boulder, cobble, moss, grass, and shrub) in addition to site-level habitat features (water volume and elevation) that in combination describe the association of Coeur d’Alene salamanders with cool and moist conditions. Coeur d’Alene salamanders appear to select streambed habitat during warm, dry periods, which may be a behavioural response to minimize dehydration during periods of activity at the surface of the forest floor. / Forestry, Faculty of / Graduate
184

The Ecological Succession of Mosquitoes Inhabiting Waste Tires in a Subtropical Swamp and Upland Forest in Central West Florida

Dinh, Emily Thuong Nguyen 01 February 2016 (has links)
Literature has not yet seen a contribution involving the description of successional patterns of mosquitoes (Diptera: Culicidae) inhabiting discarded automobile tires in sylvan areas nor an investigation into the macro- and micro-environmental factors that may influence the seasonal shifts in species composition and abundance in that respective habitat. Waste tires in undeveloped forests are a hazard to human and animal health because they can support a population of vector mosquitoes. Locating productive waste tire mosquito habitats is problematic in wooded areas but is crucial for diminishing pathogen transfer in areas where humans have regular access to forests because of possible zoonotic disease transmission. The intentions of this study were 1) to describe the ecological succession patterns of mosquitoes in waste tires in a subtropical wetland and upland forest and 2) to create a database on which regressive geo-spatiotemporal models locating unidentified productive waste tires in sylvan zones can be built. The entomological research conducted here did not confirm the hypothesis that Aedes albopictus (Skuse) would be the dominant species in all the tires at all the study sites. There appeared to be seasonal trends in mosquito production despite the general constant warmth and rainfall levels year-round in subtropical Tampa, Florida. However, the findings of this research indicates that climatic conditions alone do not sufficiently explain spatiotemporal variation in mosquito populations. Rather, the effects of weather are heterogeneous at the microcosmic level, which has a more direct impact on ecological interactions between the different species found here and their abiotic environment.
185

Contribution au recensement des cétacés dans l'archipel de Guadeloupe / Contribution to the census of cetacean in the Guadeloupe archipelago

Gandilhon, Nadège 06 July 2012 (has links)
Au cours de 325 relevés, 518 observations visuelles et 202 acoustiques ont permis de recenser 4 familles, 14 genres et 17 espèces, représentant un effectif total cumulé de près de 6000 cétacés contactés dans les limites de 15 mille nautiques des côtes en Guadeloupe. Les dauphins (Delphinidëe), constituent 33% des 36 espèces actuellement connues dans le monde. Six espèces plus rares ont été décrites. Parmi les cétacés à fanons, la baleine à bosse (Megaptera novaeangliae) migre dans les eaux côtières de décembre à fin mai et reste l'espèce la plus rencontrée. Grâce à un suivi individuel par télémétrie, il a pu être prouvé qu'au moins un individu de cette espèce pouvait séjourner dans l'archipel plus de huit jours. En 2010, une baleine à bosse de la baie du Moule à été suivie sur plus de 6300 kilomètres jusqu'au sud de l'Islande, vers les Iles Féroé. Une première estimation de stock sur la période de 2008 à 2011 propose que 442 baleines à bosse %CV 19,29 IC95% [302-645] évolueraient dans l'archipel côtier. Les carnïvores sont les plus abondants, avec parmi ceux-ci, le dauphin tacheté pantroplcal (Stenella attenuata) dont l'estimation indique que 270 à 300 individus évolueraient sur 1361 km2 avec une densité relative élevée (0,052 tndtvtdus/km>, %CV 90,16), principalement en-côte-sous-le-vent. L'analyse de la répartition spatiale et des facteurs du milieu indique une sectorisation géographique marquée des populations en zone côtière, avec des distributions influencées spécifiquement par la bathymétrie, la latitude, les distances à la côte et à l'isobathe 200, pour les informations principales et selon les espèces. / In 325 surveys, 518 visuai observations and acoustic 202 have identified four families, 14 genera and 17 species, representing a cumulative total ofnearly 6000 cetaceans assessed within 15 miles of coastal water ofGuadeloupe. Dolphins (Delphinidae), constitute 33% ofthe 36 species currently known in the world. Six rare species have been described. Among the baleen whales, the humpback whale (Megaptera novaeangliae) migrate into coastal waters from December to late May and is the species most encountered. With individual monitoring by telemetry, it has been proved that at least one individual ofthis species could stay in the archipelago over eight days. In 2010, a humpback whale in the Bay ofmold were followed for more than 6300 km to the south ofIceland to the Faroe Islands. A first estimate ofstock over the period 2008 to 20 Il suggests that 442 humpback whales CV% 19.2995% [302-645] would evolve in the coastal archipelago. <..';:-.'") Carnivores are the most abundant, with among them, the spotted dolphin (Stenella attenuata) whose estimate indicates that 270 to 300 individuals are present over 1361 km 2 with a high specifie density (0.052 individuals / km 2,% CV 90, 16), mainly in the Leeward coast. The analysis ofthe spatial distribution and environmental factors indicates a marked geographical sectorisation ofpopulations in coastal areas, with distributions specifically influenced by bathymetry, latitude, distance to the coast and the isobath 200, depending on the species
186

Variations in mineral abundance within a single horizontal well path in the Woodford Shale, Arkoma Basin, Oklahoma

Wehner, Tyrel David January 1900 (has links)
Master of Science / Department of Geology / Matthew W. Totten / The Woodford Shale (Oklahoma, U.S.A.) is a prolific unconventional hydrocarbon resource. The Woodford has been shown to be heterogeneous in many geochemical, mineralogical, and rock mechanic properties across the state of Oklahoma, which presents a challenge to successful exploitation of this resource (Caldwell, 2014; Turner et al., 2015; Wiley, 2015; Zhang et al., 2017). Most prior studies of the Woodford Shale report properties from a single sample collected from a vertical well, which reports these values as a single point source on a distribution map. Studies using outcrop localities report lateral variations in several rock properties of the Woodford, but are limited to the short distances an outcrop provides (Turner et al., 2015). The main focus of this research is to determine whether rock properties important to the productivity of the Woodford Shale vary across a lateral well bore within the Woodford shale. Measurements of chemical and mineralogical compositions were performed on rock cutting samples from a single horizontal well path of the Carleigh 6H-32 across approximately one mile. The mineral makeup was determined by use of X-ray diffraction (XRD) and elemental concentrations were determined by hand-held X-ray fluorescence (HHXRF). What was found is that the Upper and Middle Woodford Shale are relatively homogeneous laterally. The lack of variation means that it’s possible to determine from which subgroup samples may have been taken. The geochemical data were used to calculate a mineral-based brittleness index (Wang and Gale, 2009), which was compared to the measured frack gradient across perforations of the Carleigh 6H-32 well. In addition, the total organic matter content (TOC) was approximated in the same samples using loss on ignition (LOI) methods. The calculated mineralogy within samples assigned to the Middle Woodford show some variability throughout the horizontal well, which leads to an associated variation in mineral brittleness index when using the Wang and Gale (2009) formula. The mineral based brittleness index correlates with observed fracture gradient during well completion. This suggests that the tendency to fracture is also variable along the well path, which should be considered during design of the well completion.
187

A Catch Per Unit Effort (CPUE) Spatial Metric with Respect to the Western North Atlantic Pelagic Longline Fishery

Appelman, Max 01 March 2015 (has links)
Catch per unit effort (CPUE) is a quantitative method used to describe fisheries worldwide. CPUE can be presented as number of fish per 1000 hooks, number of fish per amount of fishing time, or with any unit of effort that best describes the fishery (e.g., search time, hooks per hour, number of trawls). CPUE is commonly used as an index to estimate relative abundance for a population. These indices are then applied within stock assessments so that fisheries managers can make justified decisions for how to manage a particular stock or fishery using options such as quotas, catch limitations, gear and license restrictions, or closed areas. For commercial pelagic longline (PLL) fisheries, onboard observer data are considered the only reliable data available due to the large-scale movements of highly migratory species (HMS) like tunas and because of the high costs associated with fisheries independent surveys. Unfortunately, fishery-reported logbook data are heavily biased in favor of the target species and the expense of onboard observers results in a low percentage of fleet coverage. Subsequently, CPUE derived from fishery-dependent data tends to overestimate relative abundance for highly migratory species. The spatial distribution of fish and fishing effort is essential for understanding the proportionality between CPUE and stock abundance. A spatial metric was created (SCPUE) for individual gear deployments using observer-based catch and effort data from the western North Atlantic PLL fleet. SCPUE was found to be less variable than CPUE when used as an index of relative abundance, suggesting that SCPUE could serve as an improved index of relative abundance within stock assessments because it explicitly incorporates spatial information obtained directly from the fishing location. Areas of concentrated fishing effort and fine-scale aggregations of target and non-target fishes were identified using the optimized hot spot analysis tool in ArcGIS (10.2). This SCPUE method describes particular areas of fishing activity in terms of localized fish density, thus eliminating the assumption that all fish in a population are dispersed evenly within statistical management zones. The SCPUE metric could also assist fisheries management by identifying particular areas of concern for HMS and delineating boundaries for time-area closures, marine protected areas, and essential fish habitat.
188

Histoire des mentalités et iconographie : la représentation des xenia dans les mosaïques de la Tunisie romaine / History of mentalities and iconography : the representation of xenia in the mosaics of Roman Tunisia

Karoui, Saloua-Radhia 23 January 2010 (has links)
L’étude que nous avons menée sur la représentation des xenia dans la Tunisie romaine, s’inscrit dans le cadre général du rapport de l’architecture domestique avec l’affirmation du statut social de l’élite africaine. La construction de la domus était, sans doute, un projet stratégique qui exigeait des notables une réflexion sérieuse sur la meilleure façon d’exalter les signes extérieurs de leur richesse, de leur bon goût et, en définitive, de leur appartenance à l’idéal de vie romain dans lequel l’hospitalité, exprimée par le décor de xenia, occupe une place de choix. Les mosaïques à xenia dans la Tunisie romaine sont les plus nombreuses à l’échelle de l’Empire. elles représentent trois particularités, la première concerne la composition des pavements : les motifs de xenia sont représentés isolés et, dans la plupart des cas, associés à d’autres thèmes décoratifs ; la deuxième se rapporte à la répartition de ces mosaïques dans l’espace domestique, couvrant toutes les composantes de la domus et non pas seulement les pièces réservées aux hôtes ; la troisième, enfin, touche à la sémantique des xenia qui traduit certains aspects de l’histoire mentale de l’élite Afro-romaine. / The mosaics of xenia in the Roman area of Tunisia are the most numerous at the scale of the Empire. They present three particularities, the first one concerns the compositions of the ornamental tiling: the xenia motifs are represented isolated and, in most cases, associated with other decorative themes; the second one relates to the distribution of those mosaics in the household space covering all components of the domus and not just the rooms reserved for the hosts; finally the third one touches the semantic of the xenia which does not refer itself only about hospitality.
189

Spatiotemporal Variation in Abundance and Social Structure of Bottlenose Dolphins in the Florida Coastal Everglades

Sarabia, Robin E 09 November 2012 (has links)
Bottlenose dolphins (Tursiops truncatus) are large-bodied predators that are locally abundant in the coastal Everglades. Because of their potential to exert strong top-down effects on their communities, it is important to understand how spatiotemporal variation in biotic and abiotic factors affects the abundance and behavior of dolphins. This study combined two years of transect surveys with photographic identification methods to assess spatiotemporal variation in the abundance and group sizes of bottlenose dolphins across four large regions of the coastal Everglades including the Shark and Harney Rivers, Whitewater Bay, and coastal oceans of the Gulf of Mexico and Florida Bay. Dolphin abundance was similar across wet and dry seasons, except in river habitats where abundances were higher during the dry season. Group sizes were largest in Florida Bay and open water. Dolphins may be relatively resilient to abiotic changes in the coastal Everglades, with the possible exception of river habitats.
190

Bumblebee abundance decreases with growing amount of arable land at a landscape level

Fjellander, Gabriella January 2017 (has links)
Society depends on bumblebees for the ecosystem service in the pollination of crops. Bumblebee declines have been documented, mostly due to intensification of agriculture and loss of species-rich semi-natural grasslands, an important bumblebee habitat. To conserve bumblebee diversity and the ecosystem service of pollination, it is important to do analyses on multiple spatial scales to see how the intensification of agriculture affects bumblebees at a landscape level. In this study, I related abundance of bumblebees in 476 sites in southern Sweden (total abundance and abundance of declining/non-declining, long-tongued/short-tongued, and species preferring open terrain vs. forest boundaries) to amount of land use types (semi-natural grassland, arable land, forest, water and “other land use”) at 34 spatial scales (radii 100 to 40,000 m). Arable land had a negative effect on total bumblebee abundance at scales from 464 to 10,000 m and forest had a negative effect at scales from 2929 to 5412 m. Semi-natural grassland showed no clear effects – however, the partial regression coefficients were consistently negative. Arable land had a negative effect on non-declining species, long- and short-tongued species and on species preferring forest boundaries at larger scales, e.g. regions dominated by agriculture. Forest had a positive effect at smaller scales on species preferring forest boundaries and a negative effect at larger scales on species preferring open terrain and on declining species. The results suggest that arable land is a non-habitat for bumblebees and that semi-natural grassland does not affect bumblebee abundance at a landscape level.

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