A proxy for estimating the cell volume of Ceratium furcoides (Dinophyceae): basis for monitoring Brazilian reservoirs

Abstract

AbstractCeratium furcoides, a large bloom‐forming dinoflagellate, is considered an invasive species in South American freshwater systems. As it can cause ecological and economic problems, particularly in reservoirs, this issue has been discussed among researchers and companies responsible for monitoring Brazilian aquatic systems. To this end, although biovolume estimates are an important tool for ecological studies, calculating biovolumes is a cumbersome procedure, requiring a large number of samples and measurements. This study was undertaken to provide a simple measured morphological trait as a proxy for the cell volume of C. furcoides in Brazilian water systems that have been invaded by these organisms, exhibiting dense, recurrent blooms. Morphometric data were obtained monthly from two subtropical reservoirs in southern Brazil with public supply purposes. Cell volumes exhibited seasonal variations, with significant differences by months and seasons, although not between reservoirs or morphotypes with two or three antapical horns, meaning biovolume estimates must consider seasonal variations in dinoflagellate size. Body width was significantly correlated with 11 other measured dimensions of the cell and was highly correlated with cell volume, thereby being the most representative measure of cell volume. Linear regressions for estimating cell volumes from cell body width revealed a strong positive trend when both full sampling and seasonally grouped samples were considered. Morphometric data of C. furcoides invasions in other Brazilian subtropical and tropical waterbodies also were used, exhibiting significant correlation with the formula proposed in this study.