TITLE:
Benthic Diatom Communities of a Large Mediterranean River under the Influence of a Thermal Effluent
AUTHORS:
Luis Quevedo, Carles Ibáñez, Nuno Caiola
KEYWORDS:
Diatoms, Ebro River, Thermal Pollution, Nuclear
JOURNAL NAME:
Open Journal of Ecology,
Vol.8 No.2,
February
27,
2018
ABSTRACT: The influence of a thermal
discharge caused by the cooling system of a nuclear power station on benthic
diatom communities was assessed at the lower Ebro River (in Spain), and the
information generated could be useful to understand the effects of increasing
temperature on large Mediterranean rivers. Surveys conducted at sites before
and after the effluent and collected from natural and artificial substrate were
analyzed and, Non-metrical Multidimensional Scaling (NMDS), Similarity
Percentage Analysis (SIMPER) and 1-way Analysis of Similarities (ANOSIM) were
performed to assess changes in community structure. The relationship between
diatom assemblages and environmental variables was assessed with a multivariate
distance-based linear regression model (DISTLM) and the model was visualized
through a redundancy analysis (dbRDA). NMDS ordination was obtained with a
stress of 0.18 and 0.17 for natural and artificial substrates, respectively.
ANOSIM showed significant differences between Control and Impacted sites (p 0.05). Simper analysis showed that the mean dissimilarity between Control
and Impacted sites was of 42.22% for natural substrate and of 39.97% for
artificial substrate. DISTLM selected a set of explanatory variables (dissolved
oxygen, Tºdifference, total phosphorus, pH and
chlorophyll) with a 67.24% of fitted variation. Diatoms showed sensitivity to
thermal changes, even though when these did not exceed 3℃. The factors that seemed to influence
benthic assemblages the most were seasonal
variation and the thermal increase caused by the nuclear power station.