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

Abstract

Ceratium 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.

Invasion and establishment of Ceratium furcoides (Dinophyceae) in an urban lake in Porto Alegre, RS, Brazil

“…Other groups represented less than 5 % of total phytoplankton and were not considered here. Twenty individuals of C. furcoides were measured per sample to estimate cell volume, which was calculated based on the cingulum width applied to the linear regression equation proposed by Cavalcante et al (2018). Descriptive analyses were performed with the data to observe their temporal patterns (seasonal and interannual).…”

Spreading of the invasive dinoflagellate Ceratium furcoides (Levander) Langhans throughout the Paraiba do Sul ecoregion, South America, Brazil

“…Furthermore, morphological plasticity can likewise be related to eurytopic features. Variation in size of C. furcoides over periods of time have already been detected in South American reservoirs, this such as seasonal cell-size variation (Cavalcante et al, 2018;Roriz et al, 2019) and smaller individuals (length between 118-315 µm) during blooms (Almanza et al, 2016). The broad morphometric variation in Ceratium has been considered an adaptive trait for environmental filtering, especially when dealing with changes in water temperature (Lindström, 1992;Cavalcante et al, 2016), but also the case with biotic pressures (e.g.…”

“…In the Paranoá Reservoir, Roriz et al (2019) documented abundances between 6 and 45 ind/mL. Greater abundances (between 62-103 ind/mL) were reported by Bustamante-Gil et al (2012) (Silva et al, 2012;Bustamante-Gil et al, 2012;Meichtry-de-Zaburlín et al, 2014;Morales, 2016;Crosseti et al, 2019), water column stability (Bustamante-Gil et al, 2012;Meichtry-de-Zaburlín et al, 2014;), a combination of optimal conditions of temperature (up to 25 °C), organic matter, and pH (Cavalcante et al, 2016;Cassol et al, 2017), high dissolved oxygen (Roriz et al, 2019). The eurytopic features were again evident by the presence of warm water in the SBR Reservoir (30.2 °C), and by the wide ranging variability in environmental conditions in which this species appeared to thrive within the three reservoirs (Table 1).…”

“…Considering the short retention time of the IPO reservoir (0.2 days), it can be suggested that the dinoflagellate population primarily venture from the Paraíba do Sul River. Being of small size, in tandem with an adaptation to mechanical damage due to water current, could well be a resource-saving strategy to population maintenance and propagule density increase until arriving at a more favorable environment (Hutchinson, 1967;Raven, 1998;Cavalcante et al, 2016;Sharma & Rai, 2011). Moreover, under a river-flowing condition, size may not prove an important factor in avoiding predation.…”

Temporal occurrence of Ceratium furcoides (Dinophyceae: Ceratiaceae) during an extreme drought season in Pernambuco state, Northeast Brazil

“…For cell volume (µm 3 ) calculation, twenty specimens of C. furcoides, randomly selected, were measured. The cell volume was estimated using geometric formulas adapted from Cavalcante et al (2018), where the cell has the shape: ellipsoid + 2 cones + cylinder (Fig. 3) and its volume is determined by formula:…”