Juan Pablo Pacheco Esnal
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Carlos Iglesias Frizzera
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Guillermo Goyenola
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Franco Teixeira de-Mello
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Claudia Fosalba
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Abstract
The invasive freshwater dinoflagellate Ceratium furcoides is extending its distribution in South America with increasing environmental impacts associated with its blooms. We here report two events related to C. furcoides distribution expansion in Uruguay: 1) the first appearance and main environmental drivers (physico-chemical variables, extreme wind events and zooplankton composition) of the bloom of C. furcoides in 2012 in a subtropical eutrophic shallow lake (Lake Blanca, Uruguay), and 2) the fish kill event of Prochilodus lineatus likely caused by C. furcoides in 2016 in a deep eutrophic lake (Puente de las Americas, Uruguay), which is the first fish kill attributable to C. furcoides registered in the world. The bloom of C. furcoides in Lake Blanca started in spring 2012 (October) during a clear water period with high phytoplankton species replacement after a cyanobacterial bloom of Raphidiopsis raciborskii. Extreme wind events during this period resuspended cysts from the sediments, which likely started the C. furcoides bloom. High nutrient availability and low zooplankton grazing, allowed the bloom to expand and reach 96% of the phytoplankton biomass. Our results further indicate that the fish kill of Prochilodus lineatus in Lake Puente de las Americas was likely promoted by the high biomass of C. furcoides bloom, causing gill damage and clogging together with oxygen depletion in the benthic zone. Our study is the earliest record of C. furcoides in Uruguay and it shows the drastic consequences of C. furcoides bloom in freshwaters and its potential of inducing massive fish kills.
A multifaceted approach for beech forest conservation: Environmental drivers of understory plant diversity
