Conservation of the Noronha Skink (Trachylepis atlantica, Schmidt, 1945) on the Fernando de Noronha Archipelago: reproduction, population density and sanitary evaluation

Author(s)

Vinícius Peron de Oliveira Gasparotto

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2019-10-04

Examining board members

Ricardo Augusto Dias; Marcos Bryan Heinemann; Paulo Rogério Mangini; Selma Maria de Almeida Santos; Jean Carlos Ramos da Silva

• Advisor: Ricardo Augusto Dias

Abstract

Located in the Atlantic Ocean and in the Northeast of Brazil, the Fernando de Noronha archipelago belongs to the state of Pernambuco and is composed of 21 volcanic islands, and its main island has an area of 16.9 km² (Olson, 1981; Carleton and Olson, 1999). The archipelago has two endemic species of reptiles, first one called two-headed snake (Amphisbaena ridleyi) and another popularly called Noronha skink (Trachylepis atlantica) (Ramalho et al., 2009). The T. atlantica showed sexual dimorphism, reproductive seasonality and the copulation and egg laying occurred during the dry season. Males actively defend their territories from other invading males and females showed no more than two eggs in the oviduct per reproductive season. In addition to the endemic species of reptiles present in the archipelago, other continental species belonging to the same class, Reptilia, were introduced: Salvator merianae and Hemidactylus mabouia. Invasive alien species threat biodiversity worldwide, especially in island environments. Two methods were used to estimate the density of the Noronha Skink. The density for the main island was 0.167 ind./m² ± 0.090 ind./m²; for the secondary islands it was 0.357 ± 0.170 ind./m²; and for the whole archipelago it was 0.184 ± 0.109 ind./m². The animals present in the secondary islands presented larger morphometric parameters than the individuals present in the main island. In these environments, endemic species are more vulnerable to predation and competition for resources, as well as to diseases brought by the introduced species, which may cause their extinction. Microorganisms of the oral and cloacal cavity were identified, as well as the occurrence of ectoparasites. Body mass index and hematological parameters were determined from healthy individuals. Thus, this project generated technical elements for the promotion of conservation. In this way, the main objective of this project was to offer technical elements for the promotion of the conservation of this endemic species that has undergone a series of anthropic pressures in the Archipelago of Fernando de Noronha. To achieve this, we characterized the reproductive biology, population density and the sanitary evaluation of the Noronha skink population was carried out. Until the elaboration of the present project, such informations were not available in the scientific literature. Results showed the likely decline of the Noronha Skink population present on the main island. Finally, we set the basis for a management and conservation plan of this endemic species along with environmental analysts of ICMBio and local members of the community. (AU)

• FAPESP's process: 16/16433-1 - Conservation of the Mabuya (Trachylepis atlantica, Schmidt, 1945) in the Archipelago of the Fernando de Noronha - PE: a sanitary evaluation, reproduction and population dynamics
• Grantee: Vinicius Peron de Oliveira Gasparotto
• Support Opportunities: Scholarships in Brazil - Doctorate