Phytoplankton based water quality metrics: feasibility of its application in a neotropical shallow lake

MELINA DEVERCELLI; DIEGO FRAU; GISELA MAYORA

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2018

1323-1650

Urban lakes constitute important recreational areas, but often they are eutrophicated. In this study we discuss the utility of twelve ecological quality metrics to test whether: (1) they can be applied in neotropical lakes, (2) they are sensitive to environmental variations throughout the year and (3) they are affected by heterogeneous spatial distribution of phytoplankton. Phytoplankton and environmental variables (including nutrients) were monthly sampled in an urban lake (four littoral and one limnetic station) throughout a year (n=60). Twelve ecological quality metrics were tested using total phosphorus as a proxy of eutrophication through General Lineal Models (GLM). The best adjusted metrics were then transformed to an Ecological Quality Ratio (EQR) to allow comparisons. The Phytoplankton Assemblage Index (Q-index) and the Cyanobacteria Bloom Index (CBI) were the most accurate ones. Differences in the water quality estimation occurred across the year, with an over-estimation of the water quality in absence of cyanobacteria blooms. No differences occurred due to the effect of phytoplankton spatial distribution. The Q-index was related to temperature and soluble reactive phosphorus and the CBI to conductivity. We conclude that the Q-index is the most accurate metric for monitoring purposes, responding well to phosphorus variation.