Macroalgas como ferramenta de avaliação do estado de conservação de ecossistemas costeiros

Abstract

The central objective of this thesis is to investigate and validate the use of macroalgae as bioindicator tools in the assessment of environmental quality in coastal ecosystems, structured into two interdependent chapters. In Chapter I, a systematic review of the international scientific literature was conducted, focusing on the application of macroalgae as bioindicators in different coastal zones, particularly rocky shore and reef environments, due to the absence of studies in mangroves. The critical analysis of the studies revealed a growing recognition of the effectiveness of these algae in detecting environmental impacts, as well as methodological advances in the use of ecological index based on their communities. Furthermore, a significant gap was identified regarding the application of this type of tool to mangrove ecosystems. In Chapter II, the research applied an Environmental Disturbance Index (EDI), based on the frequency of occurrence of macroalgae, to evaluate potential impacts on the Amazonian mangroves of São Luís Island, Maranhão, Brazil. Four macroalgal species were identified (Bostrychia radicans, Catenella caespitosa, Cladophoropsis membranacea, and Rhizoclonium africanum), whose distributions revealed distinct spatial patterns and persistence even under environmental pressures and seasonal changes throughout the year. The EDI proved to be a promising tool for environmental assessment in estuarine zones, highlighting indicator species as well as areas of greater and lesser ecological impact. The integrated results of this thesis reinforce the use of macroalgae as efficient bioindicators in coastal monitoring programs and underscore their relevance for the monitoring of vulnerable tropical ecosystems such as mangroves. Finally, this thesis directly contributes to the United Nations Sustainable Development Goals (SDGs), particularly SDG 13 (Climate Action) and SDG 14 (Life Below Water), by proposing scientific tools applicable to the monitoring, management, and conservation of threatened natural environments such as mangroves.