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Advances in the aquatic sciences
RESEARCH ARTICLE

Benthic diatoms in relation to environmental factors in an allochthonous river from Patagonia, Argentina

Camilo Vélez-Agudelo https://orcid.org/0000-0002-1782-233X A B C and Marcela A. Espinosa A B
+ Author Affiliations
- Author Affiliations

A Instituto de Geología de Costas y del Cuaternario, Universidad Nacional de Mar del Plata/CIC, Dean Funes 3350, Mar del Plata 7600, Argentina.

B Instituto de Investigaciones Marinas y Costeras, CONICET/UNMdP, Universidad Nacional de Mar del Plata, Dean Funes 3350, Mar del Plata 7600, Argentina.

C Corresponding author. Email: kmilovelez82@gmail.com

Marine and Freshwater Research 72(9) 1340-1352 https://doi.org/10.1071/MF20249
Submitted: 13 August 2020  Accepted: 9 March 2021   Published: 19 April 2021

Abstract

Natural and human pressures increasingly threatening the biodiversity and water resources of dryland rivers. Fluvial environments of Patagonia harbour high diatom diversity, but their management value is overlooked. The aim of this study is to explore the diatom distribution in surface sediments of the Chubut River and evaluate their relationship with environmental variables. In total, 243 diatom taxa were identified in 16 littoral zone sites. The physical and chemical variables independently explained the variance in diatom data, whereas sediment texture had a low influence. Conductivity, major ions (HCO3, Cl, SO42–, Na+, K+, Ca2+ and Mg2+) and pH were the main environmental drivers explaining the diatom composition. As the highlighted variables increased near the mouth, so did the relative abundances of marine–brackish taxa such as Amphora copulatoides, Sarcophagodes alfred-wegeneri, Nitzschia fonticola and Tryblionella apiculata. Meanwhile, the presence of high pollution-tolerant diatoms can be put forward to explain the river health deterioration towards downstream areas. The marine–brackish taxa found at freshwater sites reflect a weak tidal influence in the estuary compared with other coastal systems of Patagonia. This study provides valuable information to test the hypothesis on the ecological status of aquatic resources and the potential effects of climatic and hydrological changes in the area.

Keywords: algae, benthos, freshwater, estuarine, ecohydrology.


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