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Análise estrutural/comportamental da população de cágado mediterrânico, Mauremys leprosa, na ribeira temporária da Asseca
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Abstract(s)
Este estudo tem como finalidade caracterizar a população de Mauremys
leprosa na Ribeira da Asseca, através da análise do tamanho e estrutura populacional,
pela determinação dos parâmetros morfométricos e ecológicos e, para além disso,
estudar a relação existente entre a presença da espécie e os parâmetros ambientais.
Esta população apresenta uma grande disparidade na sua distribuição a nível
espacial, estando a sua actividade directamente relacionada com a época do ano. No
entanto, esta actividade não se mantém independente das elevadas temperaturas
registadas na ribeira.
Na realidade, a população/amostra apresenta uma densidade intermédia e uma
estrutura populacional de acordo com as populações da Península Ibérica, com uma
razão entre sexos equilibrada de 0,46.
Os valores morfométricos indicam um comprimento de carapaça máximo de
235 mm para as fêmeas e 189 mm para os machos. Confirmou-se o dimorfismo sexual
nesta população e comprovou-se que a grande maioria da população amostrada se
encontrava em boa condição corporal.
Através da análise dos parâmetros ambientais (Análise de Clusters) foi possível
distinguir 5 microhabitats distintos e relacioná-los com a presença da espécie. O maior
número de indivíduos foi detectado nos pontos de amostragem mais protegidos e na
proximidade de pontos de água permanentes. Esta espécie parece assim evitar os locais
onde existe maior pressão humana e/ou onde o curso de água é intermitente.
This study intended to characterize populations of the turtle Mauremys leprosa distributed in Ribeira da Asseca, a Southern Portugal stream. Population size and structure as well as morphometric and ecologic parameters were registered from May 2007 to August 2008, in order to investigate its relationships with the environment. Spatial distribution was irregular during this period showing that these turtles exhibited alternate activity patterns directly related to the season of the year and that activity wasn´t maintained regardless of the high temperatures recorded in this stream. Although its intermediate densities, this population has a structure and a sex ratio (0,46) in conformity with what is known from other studied M. leprosa populations in Iberian Peninsula. Sexual dimorphism was also confirmed with females and males presenting a maximum carapace length of 235mm and 189 mm, respectively. It was also found that the greater part of the population sampled presents a good body condition. Cluster Analysis of environmental parameters allows the classification of 5 microhabitats and to relate them with the presence of the species. This greater abundances were related to the more protected sites and with permanent water bodies. This species seams to avoid sites with higher human pressure and/or with intermittent water bodies.
This study intended to characterize populations of the turtle Mauremys leprosa distributed in Ribeira da Asseca, a Southern Portugal stream. Population size and structure as well as morphometric and ecologic parameters were registered from May 2007 to August 2008, in order to investigate its relationships with the environment. Spatial distribution was irregular during this period showing that these turtles exhibited alternate activity patterns directly related to the season of the year and that activity wasn´t maintained regardless of the high temperatures recorded in this stream. Although its intermediate densities, this population has a structure and a sex ratio (0,46) in conformity with what is known from other studied M. leprosa populations in Iberian Peninsula. Sexual dimorphism was also confirmed with females and males presenting a maximum carapace length of 235mm and 189 mm, respectively. It was also found that the greater part of the population sampled presents a good body condition. Cluster Analysis of environmental parameters allows the classification of 5 microhabitats and to relate them with the presence of the species. This greater abundances were related to the more protected sites and with permanent water bodies. This species seams to avoid sites with higher human pressure and/or with intermittent water bodies.
Description
Dissertação de Mestrado, Biologia Marinha, Especialização em Ecologia e Conservação Marinha, Faculdade de Ciências do Mar e Ambiente, Universidade do Algarve, 2009
Keywords
Cágados Mauremys leprosa Estrutura populacional