Grazing impacts of the invasive bivalve Limnoperna fortunei (Dunker, 1857) on single-celled, colonial and filamentous cyanobacteria

Abstract

Feeding behavior of the invasive bivalve Limnoperna fortunei in the presence of single-celled, colonial, and filamentous cyanobacteria was tested in laboratory experiments to evaluate the effects of size and shape on mussel feeding. The first hypothesis holds that golden mussel filters more efficiently smaller particles, such as single cells of Microcystis, which could be more easily assimilated by its filtering apparatus. The second hypothesis sustains that L. fortunei filters more efficiently rounded colonies, such as Microcystis, which would be more easily ingested than lengthy filamentous, such as Planktothrix. Filtration rates of golden mussel in the presence of single-celled, colonial and filamentous cyanobacteria were similar. Nevertheless, there was a great difference in the ingestion and pseudofeces production rates. Single cells were widely accepted as food, while filamentous and colonial cyanobacteria were massively expelled as pseudofeces. The results confirmed the first hypothesis that golden mussel prefers to ingest smaller particles. The second hypothesis was rejected since filamentous were preferentially ingested than colonial cyanobacteria. Golden mussel has the potential to remove toxic cells (Microcystis), however this potential would be reduced in cyanobacteria blooms, where colonial forms which are preferentially rejected by L. fortunei, are predominant. In this case, the presence of this invasive bivalve could also enhance the occurrence of blooms by rejecting colonial and filamentous cyanobacteria in pseudofeces.Keywords: golden mussel, Microcystis, Planktothrix, filtration rates, exotic species. Impactos da filtração do bivalve invasor

Acumulação de microcistinas no mexilhão dourado Limnoperna fortunei e riscos para a biota aquática

“…Estudos em laboratório envolvendo a ingestão de células de Microcystis tóxicas por L. fortunei reforçam a ideia de um possível mecanismos de desintoxicação, garantindo, assim, sua tolerância às cianotoxinas mesmo após prolongada exposição (GAZULHA et al, 2012;BOLTOVSKOY et al, 2013). A literatura elucida que os bivalves marinhos e de águas doces representam o grupo dos moluscos mais resistentes às toxinas de cianobactérias e capazes de transferi-las ao longo da cadeia alimentar (MARTINS & VASCONCELOS, 2009).…”

“…Um aspecto amplamente discutido na literatura sobre as florações de cianobactérias avalia a possível transferência de suas toxinas (microcistinas) ao longo da cadeia alimentar sob ausência de biomagnificação SMITH & HANEY, 2006), o que sugere um risco potencial às espécies de níveis tróficos superiores e ao humano no consumo de produtos aquáticos contaminados (ZHANG et al, 2009b). Essa hipótese vem sendo aceita como provável, visto que trabalhos reforçam a coexistência de L. fortunei com cianobactérias tóxicas sem prejuízos a sua sobrevivência e ao seu comportamento alimentar (GAZULHA et al, 2012).…”

Physiological and Metabolic Responses of Marine Mussels Exposed to Toxic Cyanobacteria Microcystis aeruginosa and Chrysosporum ovalisporum

“…The invasive golden mussel (L. fortunei) showed, in laboratory experiments, similar rates of filtration of single-celled, colonial and filamentous nontoxic cyanobacteria [39]. Nevertheless, whereas single-celled Microcystis were ingested, filamentous Planktothrix and colonial Microcystis were eliminated by mussels in pseudofaeces [39]. Zebra mussels (D. polymorpha), on the other hand, showed increased clearance rates of a filamentous and toxic Planktothrix agardhii strain, over a non-toxic P. agardhii strain and colonial M. aeruginosa, in laboratorial grazing experiments [35].…”

“…Bivalve grazing on filamentous cyanobacteria is relatively less known compared to unicellular or colonial cyanobacteria species like M. aeruginosa. The invasive golden mussel (L. fortunei) showed, in laboratory experiments, similar rates of filtration of single-celled, colonial and filamentous nontoxic cyanobacteria [39]. Nevertheless, whereas single-celled Microcystis were ingested, filamentous Planktothrix and colonial Microcystis were eliminated by mussels in pseudofaeces [39].…”

Three invasive species occurring in the diets of fishes in a Neotropical floodplain

“…Invasive species have the potential to alter the structure of aquatic ecosystems, because of their rapid establishment and high densities (Darrigran and Damborenea, 2011;Gazulha et al, 2012). Although species distribution changes naturally over time, human activities greatly increase the rate and the spatial scale of these changes, by accidentally or deliberately moving organisms across the world (Ricciardi and MacIsaac, 2000).…”