Unpublished conference/Abstract (Scientific congresses and symposiums)
Diversity, optimal conditions and tolerance of planktonic cyanobacteria to different environmental conditions in Chile, South America
Almanza, Viviana; Wilmotte, Annick; Laughinghouse IV, Haywood et al.
201818th International Conference on Harmful Algae (ICHA 2018)
 

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Keywords :
cyanobacteria; Chile; Blooms; lakes; biodiversity
Abstract :
[en] Abstract: Phytoplankton samples from 23 Chilean freshwater bodies (lotic and lentic) monitored by the General Water Directorate and by the EULA Center were examined to identify the diversity, optimal conditions and tolerance of planktonic cyanobacteria to different conditions. We selected ecosystems between 34 - 41° S latitude with different environmental conditions (trophic status) and human intervention in the watershed (land usage). Cyanobacteria and overall phytoplankton were identified and their abundance and biovolume were determined using the Utermöhl method. In seven lakes or rivers with visible blooms, samples were identified using a polyphasic approach, in which morphological, ecological and molecular markers (rRNA loci) were integrated. The optima and tolerance of each cyanobacterial genus at different conditions was calculated by weighted average regression (WA). The relationship among the genera and the environmental characteristics (water temperature, pH, transparency, dissolved oxygen, nitrogen and total phosphorus) were evaluated by pRDA. The results showed that cyanobacteria were found in all lakes, although they were rare (less than 5% abundance) at the southern limit. In total, 15 genera were identified morphologically, 6 Chroococcales (Aphanocapsa, Aphanothece, Gomphosphaeria, Limnococcus, Merismospedia, Microcystis), 1 Spirulinales (Spirulina), 3 Synechococcales (Coelomoron, Snowella, Pseudanabaena), 4 Nostocales (Anabaenopsis, Aphanizomenon, Dolichospermum, Nodularia) and 1 Oscillatoriales (Oscillatoria). The same genotype (16S rRNA) of Microcystis aeruginosa was distributed in the eutrophic ecosystems between 34 and 37°S and formed dense blooms. Blooms of picocyanobacteria (e.g. Cyanobium) and other filamentous cyanobacteria, such as Anabaenopsis elenkinii and Aphanizomenon ovalisporum,were also observed. In general, cyanobacteria correlated positively with eutrophic ecosystems located at lower latitudes (34 - 37°S), with a total P concentration (min - max: 0.3 - 1.9 mg L-1), and where the river basin was urbanized or used for monoculture tree plantations. The low nutrient concentration limited cyanobacterial abundance in oligotrophic systems. The comparison between ecosystems of different latitudes can be an indicator of the long-term status of cyanobacteria (species diversity and abundance) in the context of global climate change. In the Southern Hemisphere, climate change projections indicate warming, together with reduced precipitation, and a higher incidence of extreme events (periods of rain and drought). If the nutrient conditions increase, genera such as Microcystis, Aphanocapsa, Aphanothece, Aphanizomenon could be favored, together with a higher abundances of Dolichospermum.
Research center :
CIP - Centre d'Ingénierie des Protéines - ULiège
Disciplines :
Aquatic sciences & oceanology
Environmental sciences & ecology
Microbiology
Author, co-author :
Almanza, Viviana
Wilmotte, Annick  ;  Université de Liège - ULiège > Département des sciences de la vie > Physiologie et génétique bactériennes
Laughinghouse IV, Haywood ;  Université de Liège - ULiège > Département des sciences de la vie > Physiologie et génétique bactériennes
Pedreros, P
Urrutia, Roberto
Language :
English
Title :
Diversity, optimal conditions and tolerance of planktonic cyanobacteria to different environmental conditions in Chile, South America
Publication date :
October 2018
Number of pages :
1
Event name :
18th International Conference on Harmful Algae (ICHA 2018)
Event organizer :
International Society for the Study of Harmful Algae (ISSHA)
Event place :
Nantes, France
Event date :
21-26 October 2018
Audience :
International
References of the abstract :
ICHA 2018 Abstract book, page 68, Oral communication O-055
Name of the research project :
Bilateral cooperation Chile/WBI International on Chilean lakes
Funders :
WBI - Wallonia-Brussels International [BE]
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
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since 17 January 2019

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