Unusual cohabitation and competition between Planktothrix rubescens and Microcystis sp. (cyanobacteria) in a subtropical reservoir (Hammam Debagh) located in Algeria

Abstract

Succession in bloom-forming cyanobacteria belonging to distant functional groups in freshwater ecosystems is currently an undescribed phenomenon. However in the Hammam Debagh reservoir (Algeria), P. rubescens and Microcystis sp. co-occur and sometimes proliferate. With the aim of identifying the main factors and processes involved in this unusual cohabitation, water samples were collected monthly from February 2013 to June 2015 at the subsurface at four sampling stations and along the entire water column at one sampling station. In addition, the composition of the cyanobacterial communities was estimated by Illumina sequencing of a 16S rRNA gene fragment from samples collected over one year (October 2013-November 2014). This molecular approach showed that the Hammam Debagh reservoir displays high species richness (89 species) but very low diversity due to the high dominance of Microcystis in this community. Furthermore, it appears that Planktothrix rubescens and Microcystis sp. coexisted (from September to January) but proliferated alternately (Spring 2015 for P. rubescens and Spring 2014 and Autumn 2014/2015 for Microcystis). The main factors and processes explaining these changes in bloom-forming species seem to be related to the variation in the depth of the lake during the mixing period and to the water temperatures during the winter prior to the bloom season in spring.

Chemically mediated interactions between Microcystis and Planktothrix: impact on their growth, morphology and metabolic profiles

“…In temperate eutrophic freshwaters, Microcystis and Planktothrix may co-occur, with Planktothrix being an early colonizer and Microcystis appearing subsequently (Engelke et al, 2003;Jang et al, 2006;Pitois et al, 2014;Reichswaldt et al, 2015;Guellati et al, 2017). In a previous laboratory study, Engelke and colleagues (2003) reported an increase of MC concentrations in M. aeruginosa PCC 7820 cells in response to the presence of the non-MC-producing P. agardhii CYA 29 or its spent medium, and that this interaction led to an inhibition of P. agardhii growth.…”

Cyanobacteria Dynamics in a Mediterranean Reservoir of the North East of Algeria: Vertical and Seasonal Variability

“…The dominance of this genus was also found in other Algerian reservoirs used for drinking water [Guellati et al, 2017;Nasri et al, 2007;Saoudi et al, 2015]. Microcystis blooms frequently occur in the ecosystems containing N 2 -fixing cyanobacteria belonging to the genera Aphanizomenon, Dolichospermumand Cylindrospermopsis [Wu et al, [Guellati et al, 2017]. According to [Guellati et al, 2017], these two genera were only found in a restricted number of samples, in which they have always displayed very low abundance in this water pond.…”

“…Our results show that the most dominant genus of cyanobacteria was Microcystis; this genus is present throughout the water column and during the entire year. The dominance of this genus was also found in other Algerian reservoirs used for drinking water [Guellati et al, 2017;Nasri et al, 2007;Saoudi et al, 2015]. Microcystis blooms frequently occur in the ecosystems containing N 2 -fixing cyanobacteria belonging to the genera Aphanizomenon, Dolichospermumand Cylindrospermopsis [Wu et al, [Guellati et al, 2017].…”

“…In Algeria, the climate change and water degradation provided ecological conditions for the development of cyanobacteria in many aquatic ecosystems. However, a monitoring of the environmental conditions and phytoplankton assemblages was carried out in several freshwater reservoirs and lakes from which problems of eutrophication and harmful algal blooms were reported [Nasri et al, 2008;Ouartsi et al, 2011;Djabourabi et al, 2014;Boussadia et al, 2015;Saoudi et al, 2015;Bidi-Akli et al, 2017;Saoudi et al, 2017;Guellati et al, 2017]. The Zit-Emba reservoir, located in the northeastern region of Algeria, was built to provide drinking water supplies and agricultural irrigation.…”

Vertical and horizontal distribution of the microcystin producer Planktothrix rubescens (Cyanobacteria) in a small perialpine reservoir

“…Nevertheless, besides the more recent discovery of populations living in Eastern Europe (Vasas et al, 2013), records of this species were documented in many Mediterranean regions, including Central and Southern Italy ( Messineo et al, 2006;Assennato et al, 2010), Sicily (Naselli-Flores and Barone, 2000), Spain (Almodóvar et al, 2004), Greece (Vareli et al, 2009) and Turkey (Akçaalan et al, 2014;Köker et al, 2017). More recently, this species has also been identified in Northern Africa (Guellati et al, 2017). The taxonomic position of this species has been widely investigated based both on phenotypic characters (Komárek and Anagnostidis, 2005) and genetic markers (D'Alelio et al, 2013;Gaget et al, 2015;Kurmayer et al, 2015;Salmaso et al, 2016;Suda et al, 2002).…”