The present paper presents the first population data for the Southern Hemisphere of the rare seagrass Halophila baillonis. The population studied is located in a calm, reef-protected area at depths ≤ 5 m, covering 12,000 m2 (400 m long by 30 m wide, oriented parallel to the coastline). The population generally demonstrated low shoot density and biomass during the rainy season, with significant differences between seasons, being found only for aboveground biomass. Despite the identification of this new population, the species continues to be considered rare along the Brazilian coast.
Multiple stress mechanisms have caused a worldwide decrease in seagrasses, which are vulnerable to environmental and/or anthropogenic pressure. The loss of seagrass meadows of Halodule wrightii is reported for the littoral of Itamaracá Island (Northeastern Brazil). The present study identified the main anthropogenic factors that negatively influenced over the abundance and distribution of seagrass meadows between July and September 2007 at the Jaguaribe and Pilar Beaches, Eastern littoral of Itamaracá. Anthropogenic impact included the discharge of untreated sewage through fluvial channels, urban and commercial development along the coast, the anchoring of motorized and non-motorized boats, diverse fishing techniques and the dumping of solid waste. The data indicates that the Pilar is an environment with a higher impact index (71.43%) when compared with the Jaguaribe (57.14%), standing out the number of boats with a central motor, the total number of boats, the presence of shellfish gatherers and coastal urban development. The present study reinforces the need for defining management and conservation measures for this ecosystem, which has high ecological and economic value.
Multiple stress mechanisms have caused a worldwide decrease in seagrasses, which are vulnerable to environmental and/or anthropogenic pressure. The loss of seagrass meadows of Halodule wrightii is reported for the littoral of Itamaracá Island (Northeastern Brazil). The present study identified the main anthropogenic factors that negatively influenced over the abundance and distribution of seagrass meadows between July and September 2007 at the Jaguaribe and Pilar Beaches, Eastern littoral of Itamaracá. Anthropogenic impact included the discharge of untreated sewage through fluvial channels, urban and commercial development along the coast, the anchoring of motorized and non-motorized boats, diverse fishing techniques and the dumping of solid waste. The data indicates that the Pilar is an environment with a higher impact index (71.43%) when compared with the Jaguaribe (57.14%), standing out the number of boats with a central motor, the total number of boats, the presence of shellfish gatherers and coastal urban development. The present study reinforces the need for defining management and conservation measures for this ecosystem, which has high ecological and economic value.
O objetivo do estudo foi caracterizar quatro populações de Halodule wrightii no litoral norte de Alagoas, nordeste brasileiro. Entre novembro de 2011 e janeiro de 2012 foram coletadas 12 amostras por praia, sendo quatro por mancha, sempre se evitando as bordas. Em laboratório foram determinadas a densidade, a biomassa, o comprimento e a largura de folhas, com as diferenças entre os pontos de coleta analisadas pelo teste t e ANOVA one-way. Constatou-se diferenças significativas nas características morfológicas entre as populações, sendo as plantas de Barra Grande as maiores e de Tatuamunha as mais largas. As densidades entre as praias não apresentaram diferenças significativas, contudo as plantas de Porto da Rua revelaram diferença significativa intrapopulacional. Foi confirmada a plasticidade morfológica dentro e entre as populações de H. wrightii sendo sugeridos novos estudos que incluam diferentes variáveis ambientais de qualidade de água. Palavras chave: Capim agulha; morfologia; Atlântico Tropical.
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