Modelling spatial distributions of Ceratium hirundnella and Microcystis. in a small productive British lake

Abstract

The short-term relationships between the spatial distributions of phytoplankton and the environmental conditions of Esthwaite Water, a small eutrophic lake in the English Lake District, UK, were examined using a hydrodynamic model. Spatial distributions of phytoplankton were simulated on two occasions: the first, when the population was dominated by dinoflagellates; and the second, when the population was dominated by cyanobacteria.Vertical motility of the dinoflagellate Ceratium hirundinella and buoyancy of the cyanobacteria Microcystis ssp. were estimated as functions of irradiance. Water velocity fields were estimated through solving the 3-D Navier-Stokes equations on a finite-volume, unstructured nonorthogonal grid. Simulated circulation patterns of water and phytoplankton were similar to those obtained through field observations. Near-surface drift currents were initiated by wind stress, which then generated return currents along the seasonal thermocline. Aggregations of motile Ceratium that existed near the thermocline were pushed upwind by the deep return currents and accumulated at upwelling areas. In contrast, near-surface aggregations of Microcystis were pushed downwind by the surface currents and accumulated at downwelling areas. Horizontal and vertical phytoplankton distributions resulted from the interaction between the vertical motility of the phytoplankton (dependent upon the light environment) and the velocity vectors at the depths at which the phytoplankton accumulated (dependent upon wind stress and morphometry). Modelling showed that phytoplankton motility and buoyancy greatly affect phytoplankton spatial distributions.

Behavioral response as a predictor of seasonal depth distribution and vertical niche separation in freshwater phytoplanktonic flagellates

“…While confirming the underlying importance of photoresponse as a control of motility and distribution (Bearon et al 2004;Hedger et al 2004), it shows that response to chemical factors also influence the distributions of some species (such as Chlamydomonas sp. and E. gracilis).…”

Spatial Heterogeneity of Cyanobacteria and Diatoms in a Thermally Stratified Canyon‐Shaped Reservoir

“…The reported spatial variations were closely related with those that developed in the vertical plane, as organisms that concentrate at different depths in the water column were transported to different locations by water currents (TRIMBEE and HARRIS, 1983;GEORGE and WINFIELD, 2000). Thus, as a general pattern, positively-buoyant cyanobacteria rose to the surface becoming entrained in the surface drift currents (HARRIS and TRIMBEE, 1986;WEBSTER, 1990;HUTCHINSON and WEBSTER, 1994;WEBSTER and HUTCHINSON 1994;HEDGER et al, 2004), and the negativelybuoyant diatoms sank from the surface becoming entrained in sub-surface return currents (HEDGER et al, 2004). As a result, cyanobacteria aggregated in the lee wards downwelling regions, while diatoms accumulated in the windward regions of upwelling waters (SMALL, 1963;GEORGE and EDWARDS, 1976).…”

The effectiveness of conventional water treatment in removing <i>Ceratium furcoides</i> (Levander) Langhans, <i>Microcystis</i> sp. and microcystins

“…The and Bellinger, 1992;Van Ginkel et al, 2001;Naselli-Flores and Barone, 2003;Hedger et al, 2004;Matsumura-Tundisi et al, 2010). In addition, C. furcoides cell counts were high compared with Brazilian records of counts that were typically below 30 ind•mL -1 (Santos-Wisniewski et al, 2007;Silva et al, 2012;Cavalcante et al, 2013).…”