The use of Corbicula fluminea in the remediation of cyanobacterial blooms

• Autor(a) principal: Anselmo, António Eduardo Vicente
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/22395
• topic: Biotecnologia ambiental; Filtração; Cianobactérias - Eflorescência; Ameijoas; Eutrofização; Contaminação da água

Cyanobacterial blooms are frequentetly linked to eutrophication in waterbodies and can be a problem for other organisms since some cyanobacteria are toxic, not only to aquatic organisms, but also to all those ingesting contaminated water or organisms that had previously accumulated toxins in their tissues. Studies exploring new strategies to control/remediate affected waters are thus of major relevance. This motivated the present study, where the assessment of the suitability of the freshwater bivalve Corbicula fluminea as a bioremediator agent within such scenarios was aimed. Although C. fluminea is a problematic invasive species, mostly in Europe and North America, its distribution is already wide, thus the exploitation of its powerful filtration capacities can become a valuable add-on in this pest’s management via compensating damage resulting from its impacts in invaded ecosystems. In a first stage, microscopic characterisation and genetic typing were carried out over a set of laboratory cyanobacteria cultures. These represent the most common taxa composing blooms that have been monitored in national waterbodies, including strains potentially producing cianotoxins. Some of the taxa considered were Anabaena cylindrica, Microcystis and Oscillatoriales. In a second stage, the capacity of the clams to filter and ingest each cyanobacteria was assessed, using short-term assays where each cyanobacteria was offered to the clams respecting densities typically found in blooms. The results often showed low filtration rates, especially compared to those reached as a green microalgae (Raphidocelis subcapitata) was offered. However, chlorophyll a mass balance analysis in the test system (Chl a filtered, retained in pseudofaeces and non-filtered) allowed some important outcomes. The agreggation and settling of filtered cyanobacteria promoted by C. fluminea through the production of pseudofaeces was notorious. This process resembles the use of flocculants to remove organic matter and microrganisms from the water column into the bottom for further aspiration, thus opening avenues to continuing assessing the possibility of using C. fluminea as a remediation for cyanobacterial blooms.