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Contributos para o estudo da boga-portuguesa, iberochondrostoma lusitanicum collares-pereira, 1980: ecologia, reprodução e caracterização molecular
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Advisor(s)
Abstract(s)
Nas últimas décadas as ameaças à biodiversidade têm sido cada vez mais numerosas,
nomeadamente para os especialmente sensíveis ecossistemas de água doce. Estes ambientes
ocupam uma área relativamente reduzida do planeta, porém onde a perda de biodiversidade
parece ser mais elevada do que em ambientes terrestres.
A Península Ibérica (PI) constitui um sistema isolado do resto da Europa no que diz respeito a
espécies aquáticas. Este isolamento resulta da evolução geomorfológica da região com o
estabelecimento dos Pirenéus. O surgimento de formações geológicas complexas, a alteração
de escoamento das suas bacias hidrográficas e fenómenos tectónicos condicionaram o curso
dos rios e ribeiras e, consequentemente, das espécies que neles habitavam. Os peixes de água
doce, sendo peixes primários, são intolerantes à salinidade e a única forma de dispersarem é
através de contactos entre linhas de água. Como consequência, as suas histórias evolutivas estão
inevitavelmente ligadas às das bacias hidrográficas. A PI é rica em endemismos, com cerca de
80% das espécies estritamente dulciaquícolas endémicas. O mesmo se observa nas águas
continentais portuguesas com 10 endemismos lusitânicos registados.
Um desses endemismos é a boga-portuguesa, Iberochondrostoma lusitanicum Collares-Pereira
1980, espécie com estatuto de ameaça IUCN Criticamente em Perigo. Habita rios e ribeiros
pouco profundos do tipo mediterrâneo nas bacias do Tejo, Sado e Ribeiras do Oeste tendo sido
objecto de monitorizações em ambientes urbanos, particularmente, nas ribeiras da Lage,
Barcarena, Rios Jamor, Lizandro e Ota. Estas monitorizações mostram uma variabilidade na
estrutura populacional entre os vários locais e anos amostrados. Em alguns dos locais foram
detectadas espécies exóticas e invasoras e o ensombramento registado foi considerado razoável,
embora não correspondente à complexidade da galeria ripícola. Uma das ameaças conhecidas
para as espécies de água doce continentais portuguesas é a degradação dos habitats que, aliada
ao reduzido efectivo, impõe a necessidade de medidas de conservação mais imediatas que
incluem a reprodução ex situ. Para isso, foi criado um Projecto de conservação com uma
vertente de restauro ambiental associada a reprodução em cativeiro em condições seminaturalistas. A reprodução nestas condições foi bem-sucedida, com uma elevada produção de
descendentes subsequentemente libertados nos locais de origem dos reprodutores. De modo a
perceber as características das fases iniciais de vida foi registado o desenvolvimento de ovos e
larvas de I. lusitanicum de uma população do Sado reproduzida em cativeiro. As fases
embrionária e larvar, no seu conjunto, são relativamente longas, o que deixa os indivíduos
vulneráveis a perturbações e ameaças durante mais tempo. As diferentes populações de I.
lusitanicum estão isoladas em cursos de água sem contacto e para esclarecer as suas relações
filogeográficas, realizou-se uma análise molecular que confirmou existirem diferenças
significativas entre dois grandes grupos: Tejo+Oeste e Sado, e a análise morfológica dos
indivíduos foi concordante com as diferenças moleculares encontradas. Deste modo, sugere-se
a separação da população Tejo+Oeste numa espécie diferente, Iberochondrostoma tagensis.
Abstract:In recent decades, threats to biodiversity have been increasingly numerous, particularly for especially sensitive freshwater ecosystems. These environments occupy a relatively small area of the planet, but where the loss of biodiversity appears to be higher than in terrestrial environments. The Iberian Peninsula (IP) constitutes a system isolated from the rest of Europe with regard to aquatic species. This isolation results from the geomorphological evolution of the region with the establishment of the Pyrenees. The emergence of complex geological formations, changes in the flow of its river basins and tectonic phenomena conditioned the course of rivers and streams and, consequently, the species that inhabited them. Freshwater fish, being primary fish, are intolerant to salinity and the only way to disperse is through contact between watercourses. Therefore, their evolutionary histories are inevitably linked to those of river basins. IP is rich in endemism, with around 80% of strictly freshwater species endemic. The same is observed in Portuguese continental waters with 10 Lusitanian endemisms recorded. One of these is the arched-mouth nase, Iberochondrostoma lusitanicum Collares-Pereira 1980, a species with IUCN category CR- Critically endangered. It inhabits Mediterranean type shallow rivers and streams in the Tagus, Sado and Ribeiras do Oeste basins and has been monitored in urban environments, particularly in the Lage, Barcarena, Jamor, Lizandro, and Ota rivers. This monitoring show variability in the population structure between the various locations and years sampled. In some of the locations, exotic and invasive species were detected, and the shading recorded was considered reasonable, although not corresponding to the complexity of the riparian gallery. One of the known threats to Portuguese continental freshwater species is the degradation of habitats which, combined with reduced numbers, imposes the need for more immediate conservation measures that include ex situ reproduction. To this end, a conservation project was created with an environmental restoration aspect associated with captive reproduction in semi-naturalistic conditions. Reproduction under these conditions was successful, with a high production of offspring subsequently released in the breeders' places of origin. In order to understand the characteristics of the initial stages of life, the development of eggs and larvae of I. lusitanicum from a population of Sado reproduced in captivity was recorded. The embryonic and larval stages, as a whole, are relatively long, which leaves individuals vulnerable to disturbances and threats for longer. The different populations of I. lusitanicum are isolated in watercourses without contact and to clarify their phylogeographic relationships, a molecular analysis was carried out which confirmed that there are significant differences between two large groups: Tejo+Oeste and Sado, and the morphological analysis of the individuals was in agreement with the molecular differences found. Therefore, it is suggested that the Tejo+Oeste population be separated into a different species, Iberochondrostoma tagensis.
Abstract:In recent decades, threats to biodiversity have been increasingly numerous, particularly for especially sensitive freshwater ecosystems. These environments occupy a relatively small area of the planet, but where the loss of biodiversity appears to be higher than in terrestrial environments. The Iberian Peninsula (IP) constitutes a system isolated from the rest of Europe with regard to aquatic species. This isolation results from the geomorphological evolution of the region with the establishment of the Pyrenees. The emergence of complex geological formations, changes in the flow of its river basins and tectonic phenomena conditioned the course of rivers and streams and, consequently, the species that inhabited them. Freshwater fish, being primary fish, are intolerant to salinity and the only way to disperse is through contact between watercourses. Therefore, their evolutionary histories are inevitably linked to those of river basins. IP is rich in endemism, with around 80% of strictly freshwater species endemic. The same is observed in Portuguese continental waters with 10 Lusitanian endemisms recorded. One of these is the arched-mouth nase, Iberochondrostoma lusitanicum Collares-Pereira 1980, a species with IUCN category CR- Critically endangered. It inhabits Mediterranean type shallow rivers and streams in the Tagus, Sado and Ribeiras do Oeste basins and has been monitored in urban environments, particularly in the Lage, Barcarena, Jamor, Lizandro, and Ota rivers. This monitoring show variability in the population structure between the various locations and years sampled. In some of the locations, exotic and invasive species were detected, and the shading recorded was considered reasonable, although not corresponding to the complexity of the riparian gallery. One of the known threats to Portuguese continental freshwater species is the degradation of habitats which, combined with reduced numbers, imposes the need for more immediate conservation measures that include ex situ reproduction. To this end, a conservation project was created with an environmental restoration aspect associated with captive reproduction in semi-naturalistic conditions. Reproduction under these conditions was successful, with a high production of offspring subsequently released in the breeders' places of origin. In order to understand the characteristics of the initial stages of life, the development of eggs and larvae of I. lusitanicum from a population of Sado reproduced in captivity was recorded. The embryonic and larval stages, as a whole, are relatively long, which leaves individuals vulnerable to disturbances and threats for longer. The different populations of I. lusitanicum are isolated in watercourses without contact and to clarify their phylogeographic relationships, a molecular analysis was carried out which confirmed that there are significant differences between two large groups: Tejo+Oeste and Sado, and the morphological analysis of the individuals was in agreement with the molecular differences found. Therefore, it is suggested that the Tejo+Oeste population be separated into a different species, Iberochondrostoma tagensis.
Description
Tese apresentada para cumprimento dos requisitos
necessários à obtenção do grau de Doutor em Biologia
do Comportamento, apresentada no ISPA - Instituto
Universitário no ano de 2023
Keywords
Água doce Ictiofauna endémica Risco de extinção Conservação Freshwater Endemic ichthyofauna Extinction risk Conservation