Downstream transport processes modulate the effects of environmental heterogeneity on riverine phytoplankton

Caio Graco-Roza; Juliana B O Santos; Vera L M Huszar; Patrícia Domingos; Janne Soininen; Marcelo Manzi Marinho

doi:10.1016/j.scitotenv.2019.135519

Downstream transport processes modulate the effects of environmental heterogeneity on riverine phytoplankton

Sci Total Environ. 2020 Feb 10:703:135519. doi: 10.1016/j.scitotenv.2019.135519. Epub 2019 Nov 14.

Authors

Caio Graco-Roza¹, Juliana B O Santos², Vera L M Huszar², Patrícia Domingos³, Janne Soininen⁴, Marcelo Manzi Marinho³

Affiliations

¹ Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, State University of Rio de Janeiro, Rua São Francisco Xavier 524, PHLC, Sala 511a, 20550-900 Rio de Janeiro, Brazil; University of Helsinki, Department of Geosciences and Geography, PO Box 64, FI-00014 Helsinki, Finland. Electronic address: caiogracor@gmail.com.
² Laboratory of Phycology, National Museum, Federal University of Rio de Janeiro, 20940-040 Rio de Janeiro, Brazil.
³ Laboratory of Ecology and Physiology of Phytoplankton, Department of Plant Biology, State University of Rio de Janeiro, Rua São Francisco Xavier 524, PHLC, Sala 511a, 20550-900 Rio de Janeiro, Brazil.
⁴ University of Helsinki, Department of Geosciences and Geography, PO Box 64, FI-00014 Helsinki, Finland.

PMID: 31757554
DOI: 10.1016/j.scitotenv.2019.135519

Abstract

Environmental heterogeneity (EH) in space and time promotes niche-partition, which leads to high variation in biological communities, such as in algae. In streams, EH is highly related to the intensity of the water flow and may lead to community variation mainly during the low flow conditions. Despite the wide knowledge on the responses of phytoplankton communities to EH in lentic and semi-lentic systems, studies of riverine phytoplankton community variation are still scarce. Here, we first investigated the relationship between phytoplankton community variation and EH in different courses of the river and between seasons. We expected that under low or intermediate flow conditions, there is a positive correlation between community variation and EH. Alternatively, we did not expect any relationship between EH and community variation under high flow condition because stronger downstream transport would mask environmental filtering. We sampled nine sites monthly (May 2012 to April 2013) in a tropical river of Brazilian Southeast. We calculated EH from abiotic data whereas for community variation, here community distinctiveness (CD), we used Sorensen (CD_Sor) and Bray-Curtis (CD_Bray) dissimilarities. Differences in EH, CD_Sor and CD_Bray were tested at between-season and among-course levels. We found lower distinctiveness during the dry season when EH was the highest. Contrastingly, phytoplankton CD was the highest even when EH was low during the wet season. We found that this pattern raised from the increasing in individuals dispersal during the wet season, promoting mass effects. Finally, our results thus reject the first hypothesis and show a negative relationship between EH and distinctiveness. However, results support our alternative hypothesis and show that during the wet season, distinctiveness is not driven by EH. These results provide new insights into how EH drives community variation, being useful for both basic research about riverine algal communities and biomonitoring programs using phytoplankton communities as bioindicators.

Keywords: Biodiversity; Community distinctiveness; Downstream transport process; Lotic systems.

MeSH terms

Biodiversity*
Brazil
Environmental Monitoring*
Phytoplankton / classification
Phytoplankton / physiology*
Rivers*
Seasons