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Ecologia e conservação dos tubarões do arquipélago de Fernando de Noronha, com ênfase no tubarão-cabeça-de-cesto Carcharhinus perezi (Poey, 1876) (Carcharhiniformes, Carcharhinidae) /Garla, Ricardo Clapis. January 2004 (has links)
Orientador: Alberto Ferreira Amorim / Banca: Otto Bismarck Fazzano Gadig / Banca: Roberto Goitein / Banca: Emygdio Moreira Filho / Banca: Marcelo R. de Carvalho / Resumo: O presente trabalho visa gerar informações básicas sobre a ecologia e a situação populacional do tubarão-cabeça-de-cesto Carcharhinus perezi, lambarú Ginglymostoma cirratum e tubarão-limão Negaprion brevirostris no Arquipélago de Fernando de Noronha, com ênfase na primeira, por ser numericamente dominante. Utilizou-se a combinação de técnicas de marcação e recaptura e de telemetria ultra-sônica para fornecer informações sobre: estrutura populacional, distribuição espacial dos tubarões e de suas áreas de berçário, época de parto, padrões de movimentação e de utilização do hábitat. Amostras de sangue foram analisadas para caracterização sorológica das espécies. Foi implantado um programa de conscientização e educação sobre a necessidade de conservação dos tubarões, e realizou-se um curso de capacitação em Educação Ambiental para os professores do ensino médio e fundamental. A plataforma insular do arquipélago é utilizada como área de parto e de crescimento de jovens pelas três espécies de tubarões. Carcharhinus perezi apresenta maior segregação espacial por tamanho. Não ocorre segregação espacial em Ginglymostoma cirratum e Negaprion brevirostris pois foram observados indivíduos neonatos, jovens e adultos freqüentando a região próxima à linha costeira do arquipélago. Os tubarões utilizam com menor freqüência o trecho da Área de Proteção Ambiental (APA) do arquipélago, o que possivelmente está relacionado à intensificação da utilização humana e a indícios de empobrecimento biológico da região nos últimos anos. O monitoramento por telemetria mostra que: os tubarões jovens são residentes em trechos específicos do arquipélago; eles podem ser ativos a qualquer horário do dia, mas os maiores espaços de atividade e deslocamentos ocorrem à noite; aparentemente não existem variações sazonais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of the present study is to provide basic data on the ecology and population status of the reef-shark Carcharhinus perezi, nurse-shark Ginglymostoma cirratum and lemon-shark Negaprion brevirostris at Fernando de Noronha archipelago, with special reference to Carcharhinus perezi, due to its numerical dominance. A combination of mark and recapture and ultrasonic telemetry methods were used to gather data on: the population structure, spatial distribution of the sharks, location of the nursery grounds, parturition time, patterns of movement and habitat use. Blood samples were analyzed for a serological characterization of the species. An educational program was established to increase the community awareness about shark conservation, and a capacitating course on Environmental Education was offered to teachers of the local school. The archipelagos insular shelf is used as a parturition and growing ground for young sharks of the three species. Carcharhinus perezi shows size segregation. Size segregation was not observed in Ginglymostoma cirratum and Negaprion brevirostris, and neonate, young and adult sharks of these species were observed to frequent shallow waters of the archipelago. Sharks rarely frequent the archipelagos Environmental Protection Area (EPA), which is probably related to an intensification of human use and evidences of biological impoverishment of this site in recent years. The telemetry monitoring shows that: the young sharks are resident and present site fidelity to specific portions of the archipelago; they may be active at any time of the day, but the larger activity spaces and excursions occur at night; apparently there is no seasonal variation in activity spaces and habitat use; and larger sharks have more extensive activity spaces. The main problems for the management and conservation of the sharks are:... (Complete abstract click electronic access below) / Doutor
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Ecologia e conservação dos tubarões do arquipélago de Fernando de Noronha, com ênfase no tubarão-cabeça-de-cesto Carcharhinus perezi (Poey, 1876) (Carcharhiniformes, Carcharhinidae)Garla, Ricardo Clapis [UNESP] 06 January 2004 (has links) (PDF)
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garla_rc_dr_rcla.pdf: 1566045 bytes, checksum: 33a6e91849d61d578c9d020171e589af (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O presente trabalho visa gerar informações básicas sobre a ecologia e a situação populacional do tubarão-cabeça-de-cesto Carcharhinus perezi, lambarú Ginglymostoma cirratum e tubarão-limão Negaprion brevirostris no Arquipélago de Fernando de Noronha, com ênfase na primeira, por ser numericamente dominante. Utilizou-se a combinação de técnicas de marcação e recaptura e de telemetria ultra-sônica para fornecer informações sobre: estrutura populacional, distribuição espacial dos tubarões e de suas áreas de berçário, época de parto, padrões de movimentação e de utilização do hábitat. Amostras de sangue foram analisadas para caracterização sorológica das espécies. Foi implantado um programa de conscientização e educação sobre a necessidade de conservação dos tubarões, e realizou-se um curso de capacitação em Educação Ambiental para os professores do ensino médio e fundamental. A plataforma insular do arquipélago é utilizada como área de parto e de crescimento de jovens pelas três espécies de tubarões. Carcharhinus perezi apresenta maior segregação espacial por tamanho. Não ocorre segregação espacial em Ginglymostoma cirratum e Negaprion brevirostris pois foram observados indivíduos neonatos, jovens e adultos freqüentando a região próxima à linha costeira do arquipélago. Os tubarões utilizam com menor freqüência o trecho da Área de Proteção Ambiental (APA) do arquipélago, o que possivelmente está relacionado à intensificação da utilização humana e a indícios de empobrecimento biológico da região nos últimos anos. O monitoramento por telemetria mostra que: os tubarões jovens são residentes em trechos específicos do arquipélago; eles podem ser ativos a qualquer horário do dia, mas os maiores espaços de atividade e deslocamentos ocorrem à noite; aparentemente não existem variações sazonais... / The aim of the present study is to provide basic data on the ecology and population status of the reef-shark Carcharhinus perezi, nurse-shark Ginglymostoma cirratum and lemon-shark Negaprion brevirostris at Fernando de Noronha archipelago, with special reference to Carcharhinus perezi, due to its numerical dominance. A combination of mark and recapture and ultrasonic telemetry methods were used to gather data on: the population structure, spatial distribution of the sharks, location of the nursery grounds, parturition time, patterns of movement and habitat use. Blood samples were analyzed for a serological characterization of the species. An educational program was established to increase the community awareness about shark conservation, and a capacitating course on Environmental Education was offered to teachers of the local school. The archipelago s insular shelf is used as a parturition and growing ground for young sharks of the three species. Carcharhinus perezi shows size segregation. Size segregation was not observed in Ginglymostoma cirratum and Negaprion brevirostris, and neonate, young and adult sharks of these species were observed to frequent shallow waters of the archipelago. Sharks rarely frequent the archipelago s Environmental Protection Area (EPA), which is probably related to an intensification of human use and evidences of biological impoverishment of this site in recent years. The telemetry monitoring shows that: the young sharks are resident and present site fidelity to specific portions of the archipelago; they may be active at any time of the day, but the larger activity spaces and excursions occur at night; apparently there is no seasonal variation in activity spaces and habitat use; and larger sharks have more extensive activity spaces. The main problems for the management and conservation of the sharks are:... (Complete abstract click electronic access below)
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Pismo Clams (Tivela stultorum) in Califorina: Population Status, Habitat Associations, Reproduction, and GrowthMarquardt, Alexandria R 01 May 2020 (has links) (PDF)
Marine shellfish play a vital role in intertidal ecosystems and coastal communities, but many of these fisheries are small-scale and lack the necessary monitoring to ensure long-term sustainability. Effective management often requires information on key demographic parameters, such as population status, reproduction and growth. Pismo clams (Tivela stultorum) are a culturally important and iconic species in California, which supported a thriving commercial and recreational fishery throughout much of the 1900’s. However, Pismo clam populations have declined statewide in recent decades and are attributed to human harvest and predation by California sea otters (Enhydra lutris); However, no studies have examined their populations, population drivers, or life history for at least 40 years. Managers require updated and expanded information on populations, habitat associations, reproduction and growth rates to effectively manage, regulate, and recover Pismo clam in California.
In Chapter 1, we investigated current Pismo clam population levels in California and examined the role of abiotic and biotic factors as correlates of clam abundance. We quantified Pismo clam presence, density and biomass at 38 sites in California during 2018 and 2019. Our results indicate that while human population density does not appear to drive clam populations, median sediment grain size is an important predictor for Pismo clams on open coast beaches. As median grain size increases, the probability of clam presence, density, and biomass decreases, suggesting that the composition of beach habitat is a critical factor regulating Pismo clam populations. Additionally, clam density and biomass are significantly higher on beaches north of Point Conception compared to beaches south. This suggests that Pismo clam population declines are more complicated than conventional wisdom suggests. Overall, Pismo clam densities are lower and size structures are shifted towards smaller sizes than historical accounts. This study is the most comprehensive set of population surveys to date and identifies key factors associated with Pismo clam abundance, which may be used to inform management and guide restoration and recovery of this once iconic species.
In Chapter 2, we examined life history characteristics of Pismo clams in California. Specifically, we investigated the annual reproductive cycle of Pismo clams in California, pairing multiple metrics within a single study to describe the sex ratio, gonad development stages, body condition index, and length at sexual maturity. Further, we examine age-length relationships across California to provide estimates of age structure and growth rate, which will better inform recovery timelines for the recreational fishery in California. Our results indicate that the sex ratio is 1:1, peak spawning occurred in late summer, and clams can spawn in their first year (<20 >mm). Cycles of body condition were influenced primarily by mean monthly sea surface temperature, but mean monthly chlorophyll-a concentration, photoperiod, clam size, and year were also important. Body condition was significantly correlated with the proportion of clams in the Ripe stage. Thus, body condition has the potential to be a rapid, inexpensive proxy for monitoring reproduction in Pismo clams, potentially providing useful information about changes in reproductive patterns. Finally, examination of age-length relationships for Pismo clams suggest that clams may require over 13 years to reach a legally harvestable size (114 mm across most of California). The estimated age at legal size is substantially older than historical estimates, which suggested that Pismo clams could reach legally harvestable size in as few as 6 years.
Collectively, this work represents a significant advance in our knowledge of the biology and ecology of this iconic and culturally important species. Furthermore, it provides vital information on the current population status, reproduction, and growth rates to inform management, regulation, and potential recovery of Pismo clams in California.
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Distribution, population status and conservation of the samango monkey (Cercopithecus albogularis schwarzi) in the Limpopo Province, South AfricaLinden, Birthe 02 1900 (has links)
PhD (Zoology) / Department of Zoology / A general introduction about the need for studying forest dwelling primate populations in fragmented landscapes and more specifically in the Soutpansberg is given in Chapter 1. Forests affected by fragmentation are at risk of losing primate populations over the long term. In addition, although the impact of fragmentation on primate populations has been studied in many places in Africa, Asia and South America there is no consensus of how the different primate species react to forest disturbance and fragmentation. This study aims to investigate the impacts of natural and anthropogenic forest fragmentation on the Soutpansberg samango monkey population including their distribution, genetics, and phylogeography, identifying threats and mitigation measures. To date, no detailed population level research has been undertaken on samango monkey populations in the far north of their South African distribution. By collecting a diverse data set, in addition to existing ecological data, this study generates conservation and management recommendations suited specifically to the study area and the study species and provides baseline data for future monitoring.
Chapter 2 details how through creating an accurate forest distribution map and collecting samango monkey distribution records through surveys we were able to investigate how both natural and anthropogenic forest fragmentation influences the distribution of samango monkeys in the Soutpansberg. We explored forest patch occupancy and connectivity, determined the degree and nature of matrix utilisation and identified possible threats to forests and samango monkeys between the contrasting landscapes of the eastern and western Soutpansberg. Here we found that samango monkeys largely occupied forest patches <100 ha in size and that the Soutpansberg has very few forest patches > 100 ha available. We showed that samango monkeys used all components of the surrounding matrix and that lone or bachelor group males used the matrix more extensively than groups. We found that paved roads pose a major threat, however not a barrier, to samango monkey populations when navigating the matrix. Forest connectivity was found to be influenced by the distance between patches and possible corridors or stepping stones of isolated forest patches connecting them. Patterns found in this chapter contrasted between the eastern and western landscapes requiring different adaptive strategies from the samango monkeys and different conservation approaches from practitioners. In this chapter we conclude that samango monkeys, having evolved in fragmented landscapes, are comparatively tolerant and adaptable to a human-
transformed matrix.
In Chapter 3 we focused on the effects that natural and anthropogenic habitat fragmentation in the Soutpansberg has on the genetic diversity and structure of the samango monkey population in the mountain range. Here we used microsatellite and mitochondrial DNA data from faecal and tissue samples collected from four local samango monkey populations across the Soutpansberg. We also included samples from an outlying population on the escarpment south of the mountain, the most likely historical migration route into the Soutpansberg. Our analyses showed that the Soutpansberg population is divided across the mountain and that genetic diversity within the Soutpansberg decreases with increasing distance to the escarpment population and from east to west. We found a lack of contemporary gene flow suggesting that the Soutpansberg population is completely isolated from the closest source population in the escarpment and that populations within the mountain range are isolated from each other. Based on our results we suggest that extensive anthropogenic changes to the landscape in the eastern Soutpansberg and distance between high canopy forest patches in the western Soutpansberg appear to have reduced the ability of samango monkeys to disperse between sampling areas. Overall, we found that natural and anthropogenic fragmentation and geographical distance are potential drivers for the observed population genetic differentiation and that the matrix surrounding forests and its suitability for samango utilisation plays a role at the local scale. In this chapter we conclude that the degree of samango monkey population subdivision and the apparent lack of contemporary migration between populations raises concerns about the long-term viability of populations across the mountain range.
Having identified road fatalities as the main direct anthropogenic threat samango monkeys are exposed to when utilizing the matrix, we further investigated this issue in more detail in Chapter 4. Here we aimed to get a better understanding of where roadkills most likely occur and how to mitigate these through using suitable canopy overpasses. As road fatalities threaten primate populations globally, we used the samango monkey (Cercopithecus albogularis) as a model species to test the suitability of two different canopy bridge designs through field experimentation and behavioural data collection for arboreal guenon roadkill mitigation. Analysis of actual roadkill data collected in the study area provided insights into the nature of high-risk localities. We showed that canopy overpasses are a viable intervention for mitigating arboreal guenon road fatalities, reducing the probability that monkeys will cross a road on the ground. Samango monkeys clearly preferred a pole bridge over a rope ladder design and canopy bridges were preferred to trees and the ground when the tree canopy was open. Pole bridges were also used by other non-guenon primates and non-primate species. We showed that although samango road kills were not predictable in time (no seasonality), adult female and immature fatalities were predictable in space, restricted to bisected riparian zones and roads close to intact forests. We further found that adult male road fatalities can be expected in seemingly unsuitable habitat areas. This chapter highlights the importance of the correct interpretation of spatial, temporal and demographic data on road fatalities and how experimental research prior to installing crossing structures could increase mitigation impact.
In Chapter 5 we investigate the regional phylogeography of samango monkeys, providing a deeper understanding into their evolutionary history in repeatedly fragmented forest habitat due to paleoclimatic fluctuations. Here we used mtDNA and microsatellite data obtained from tissue samples from a coastal population (Vamizi Island) in Mozambique and compared this to existing data from South Africa. The additional analysis of Mozambique animals allowed us to further test the number and timing of radiation events of Cercopithecus monkeys in southern Africa. In this chapter we propose the occurrence of a single, north-south radiation event during the midPleistocene along the Afromontane forest belt and that after the Last Glacial Maximum, samango populations re-radiated into (re)established coastal forests on a more local scale.
Taking the findings from all chapters together we provide overall conclusions and conservation and management recommendations in Chapter 6. Here we also include interview data to give insights into public perceptions of samango monkeys and possible human-primate conflicts as we consider this an important aspect of conservation planning. In this final chapter we conclude that although samango monkeys appear comparatively adaptable to changes in the matrix surrounding their forest habitat, direct threats and forest patch isolation by distance may pose risks to populations in future. We advocate that conservation and management strategies aimed at the longterm persistence of the samango monkey populations and their forest habitat across the Soutpansberg should be formulated separately for the eastern and western parts of the mountain range as differing landscape variables pose different threats to forest and samango monkeys, thus requiring separate conservation and management approaches. We further recommend explicit mention of distinct management requirements for maternal groups and lone or bachelor group males to achieve a holistic conservation approach for samango monkey populations on the landscape scale. Findings of our study are not only relevant for samango monkey populations in the Soutpansberg but also for populations elsewhere in South Africa and southern Africa generally where forests and samango monkeys share the same paleohistory and current anthropogenic threats. / NRF
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