Loading...
Publication
Occurrence and distribution of Phocoena Phocoena in the Tagus Estuary, Portugal
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 910.17 KB | Adobe PDF |
Advisor(s)
Abstract(s)
Entre as décadas de 1950 e 1970, os avistamentos de botos tornaram-se cada vez
mais escassos ao longo da costa portuguesa. Desde março de 2022, o Observatório
Golfinhos no Tejo tem vindo a recolher informação acerca da distribuição espáciotemporal e comportamento de três espécies de cetáceos avistados no Estuário do Tejo,
incluindo o boto (Phocoena phocoena). Para investigar a ocorrência e utilização de
habitat no baixo Tejo, foram recolhidos dados de avistamentos de botos a partir da torre
VTS em Algés, Lisboa. Voluntários treinados utilizaram um protocolo visual para
monitorizar a área de estudo de junho de 2023 a junho de 2024. Grupos de botos foram
avistados em 6,2 horas num total de 606,73 horas de monitorização. As maiores taxas de
avistamentos ocorreram no final do verão, em agosto, setembro e outubro, contudo não
se verificaram diferenças significativas entre estações as estações do ano (H(3)=1,1296,
p>0,05) e nem entre meses (H(11)=15,058, p>0,05). Comparações relativas à utilização
do habitat revelaram diferenças significativas (H(4)=9,812, p<0,05) entre as diferentes
secções da área de estudos, com os setores 6SO e 4S (Dunn post hoc p<0,05) e 6SO e 6S
(Dunn post hoc p<0,05) diferindo significativamente. Esses resultados oferecem uma
visão importante sobre a ocorrência e as preferências de habitat do boto no estuário do
Tejo. Contudo, são necessários estudos adicionais para melhor compreender o uso do
habitat e estabelecer estratégias eficazes de conservação.
ABSTRACT: Between the 1950s and 1970s, sightings of harbor porpoises became increasingly rare along the Portuguese coast. Since March 2022, “Observatório Golfinhos no Tejo” has been collecting information on the spatial-temporal distribution and behavior of three cetacean species observed in the Tagus Estuary, including the harbor porpoise. To investigate the occurrence and habitat use in the lower Tagus, porpoise sighting data were collected from the VTS tower in Algés, Lisbon. Trained volunteers used a visual protocol to monitor the study area from June 2023 to June 2024. Porpoise groups were observed for 6.2 hours out of a total of 606.73 monitoring hours. The highest sighting rates occurred in late summer, during August, September, and October. However, no significant differences were found between seasons (H(3)=1.1296, p>0.05) or between months (H(11)=15.058, p>0.05). Comparisons regarding habitat use revealed significant differences (H(4)=9.812, p<0.05) between different sections of the study area, with sectors 6SO and 4S (Dunn post hoc p<0.05) and 6SO and 6S (Dunn post hoc p<0.05) showing significant differences. These results provide important insights into the occurrence and habitat preferences of harbor porpoises in the Tagus estuary. However, further studies are needed to better understand habitat use and establish effective conservation strategies
ABSTRACT: Between the 1950s and 1970s, sightings of harbor porpoises became increasingly rare along the Portuguese coast. Since March 2022, “Observatório Golfinhos no Tejo” has been collecting information on the spatial-temporal distribution and behavior of three cetacean species observed in the Tagus Estuary, including the harbor porpoise. To investigate the occurrence and habitat use in the lower Tagus, porpoise sighting data were collected from the VTS tower in Algés, Lisbon. Trained volunteers used a visual protocol to monitor the study area from June 2023 to June 2024. Porpoise groups were observed for 6.2 hours out of a total of 606.73 monitoring hours. The highest sighting rates occurred in late summer, during August, September, and October. However, no significant differences were found between seasons (H(3)=1.1296, p>0.05) or between months (H(11)=15.058, p>0.05). Comparisons regarding habitat use revealed significant differences (H(4)=9.812, p<0.05) between different sections of the study area, with sectors 6SO and 4S (Dunn post hoc p<0.05) and 6SO and 6S (Dunn post hoc p<0.05) showing significant differences. These results provide important insights into the occurrence and habitat preferences of harbor porpoises in the Tagus estuary. However, further studies are needed to better understand habitat use and establish effective conservation strategies
Description
Dissertação de Mestrado ,
apresentada no Ispa - Instituto Universitário para a
obtenção de grau de Mestre na especialidade de
Biologia Marinha e Conservação.
Keywords
Boto Estuário do Tejo Distribuição espácio-temporal Phocoena phocoena Conservação Harbor porpoises Tagus estuary Spatial-temporal distribution Phocoena phocoena Conservation