Water quality of the urban lagoon 1
WATER QUALITY AND PHYTOPLANKTON ASSEMBLAGES FROM A TEMPERATE
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URBAN LAGOON
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DIAMELA GIANELLO1,2; ELIZABETH ÁVILA-HERNÁNDEZ1; IRENE AGUER1 and MELINA
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CELESTE CRETTAZ MINAGLIA1,3*
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1 Universidad Autónoma de Entre Ríos (UADER). Facultad de Ciencia y Tecnología, Laboratorio de
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Indicadores Biológicos y Gestión Ambiental (IBGA), Gualeguaychú, Argentina.
8 2 Grupo de Ecología de Sistemas Acuáticos a escala de Paisaje. INIBIOMA, Universidad Nacional del 9
Comahue, CONICET, Quintral 1250, Bariloche (8400), Argentina.
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3 Universidad Nacional de General Sarmiento (UNGS), Instituto de Ciencias, Área de Biología y
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Bioinformática, Los Polvorines, Buenos Aires.
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*corresponding author
[email protected] Rocamona 117, Gualeguaychú, Entre Ríos,
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Argentina. +54 221 3142508
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ABSTRACT
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1- The objective of this work was to study the water quality of the urban lagoon from Parque Unzué
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(Gualeguaychú, Argentina) through the physical-chemical and bacteriological parameters,
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composition micro-phytoplankton assemblages and, functional groups.
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2- Twenty-two samplings in 3 sites were made during 2015-2018 and physical-chemical and
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bacteriological parameters were measured and, phytoplankton collected, identified to the lowest
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possible taxonomic level and, classified in the functional group (FG).
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3- Physical-chemical and bacteriological parameters indicated that lagoon presented high organic
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pollution and, no statistically significant differences (p < 0.05) were observed between sampling
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Water quality of the urban lagoon 24
stations, but there were differences between an annual period of sampling. In general, a detriment
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to water quality can be observed from 2015 to 2018.
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4- Micro-phytoplankton
assemblages
were
compound
by
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genera
distributed
into
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Bacillariophyceae (19), Chlorophyta (16), Cyanobacteria (7), Euglenophyta (5) and, Dinophyceae
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(1). Nineteen FG was identified and, the majority were characteristic of hypereutrophic, small,
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turbid and highly enriched lagoon.
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5- We conclude that the lagoon from Parque Unzué presented permanent organic pollution which it increased over period time.
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6- This work was the first systematic and prolonged monitoring of the water quality of the lagoon
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from Parque Unzué and allowed to define the environmental quality of the site serving as a
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baseline for the proposal of management measures.
35KEYWORDS: Gualeguaychú, Parque Unzué, functional groups, organic pollution. 36 37
INTRODUCTION
38Urban lagoons are particular ecosystems present in many cities (Mancini, Crichigno, Ortiz, & Haro, 392012) that are part of the urban ecology. These can be natural or anthropogenic origin with different 40purposes as to increase the life quality, to mitigate the effects of the urban climate (Quirós, 2007, Naselli41Flores, 2008 in Mancini et al., 2012) and to refuge of biodiversity (Crettaz-Minaglia et al., 2018). Latin42American cities have little importance to these ecosystems in urban ecology, despite the accelerated 43losses of biodiversity (Sierra-Vásquez, 2012). Moreover, urban lagoons can be considered as continental 44wetlands within the RAMSAR sites, and in the stage of the loss of natural wetlands in the Pampean 45region, it is necessary to consider them as sites susceptible to be protected (Taborda, Gianello, Aguer, & 46Crettaz-Minaglia, 2017). These are usually affected by habit fragmentation and organic pollution 47(Sorensen et al., 1998, Elosegui & Sabater, 2009 in Crettaz-Minaglia et al., 2018) impacting in the 2
Water quality of the urban lagoon 48composition and distribution of the species assemblages and, therefore these assemblages can be 49considered as urban health indicators (Hough, 1998). 50Phytoplankton is a heterogeneous assemblage of the water column that can be autotrophic, heterotrophic 51or mixotrophic (Jansson et al., 1996; Pinilla, 2000). According to Johnstone et al. (2006), the changes in 52the phytoplankton assemblage can reflect the occurrence of pollutants especially nutrients which cause a 53dramatic abundance increase of the phytoplankton (Maznah & Makhlough, 2014; Abonyi et al., 2018) 54and an increase of the tolerance species (Nannavecchia, 2016) and a decrease of sensitive species 55(Escobedo-Uría, 2010). Traditional phytoplankton monitoring is based on phytoplankton biomass or chl-a 56or accessory pigments (Mischke, Venohr, & Behrendt, 2011; Friedrich & Pohlmann, 2009, Abonyi 57Leitao, Lançon, & Padisák 2012). One of the most recent research interests is the application of the 58phytoplankton functional group approach, these classifications cluster species with common traits and 59similar responses to environmental changes and have been proposed for phytoplankton by several authors 60as Reynolds (1998); Reynolds, Huszar, Kruk, Naselli-Flores and Melo (2002); Salmaso and Padisák 61(2007); Padisák et al. (2009), Kruk et al. (2010), Abonyi et al. (2012) and Beamud, León, Kruk, Pedrozo, 62& Diaz. (2015). A particularly influential functional classification is that proposed by Reynolds et al. 63(2002) since it is based not only on the individual functional traits but also on the ranges of the 64environmental conditions in which the species are found. Kruk et al. (2010) have proposed an alternative 65classification, based on morphological aspects. In this sense, trait-based approaches have been 66increasingly applied as a tool to explain and predict the response of phytoplankton species to 67environmental conditions, both in marine and continental aquatic systems (Kruk & Segura 2012; Beamud 68et al., 2015). 69The objective of this work was to study the water quality of the lagoon from Parque Unzué through the 70physical-chemical and bacteriological parameters, composition micro-phytoplankton assemblages and, 71functional groups.
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Water quality of the urban lagoon 72 73
MATERIALS AND METHODS
74Study area description 75The urban lagoon Parque Unzué (33°00'46"S-58°29'24"W; Figure 1) is located in a park of multiples 76uses (Gualeguaychú) corresponding to Mesopotamian Pampas (Morello, Matteucci, Rodríguez, & Silva, 772012). This lagoon was described previously by Gianello (2016), Gianello et al. (2017), Taborda et al. 78(2017) and Crettaz-Minaglia et al. (2018) and, it presents native and exotic species of flora and fauna 79(Supplementary material), particularly, it has an important diversity of birds (34 species) including 80migratory species such as the white heron (Egretta thula) (Taborda et al., 2017). 81 82In situ measurement and field data collection 83In 3 sampling stations, 22 water samplings were taken between May of 2015 and May of 2018. 84Parameters in situ such as pH, water and air temperature and electric conductivity (EC) with Hanna 85HI991003 portable meter, and dissolved oxygen (DO) with YSI model 55 were measured. Meters were 86previously calibrated (APHA-AWWA-WPCF, 2013). 87A standard Secchi dish of 30-cm-diameter was used to measure the water transparency and total depth. 88Moreover, in each sampling station, one-liter of lagoon water was collected to determine physicochemical 89parameters using clean amber glass bottles. For bacteriological parameters, 250 mL of water was 90collected using a plastic sterile bottle. Besides, qualitative micro-phytoplankton samples were collected 91using a Zeppelin net (Schwoerbel, 1975) of pore=30 μm, and fixed with 50% Transeau solutionm, and fixed with 50% Transeau solution 92(Echenique et al., 2006) according to Gianello et al. (2017). Samples were homogeneous, representative 93and conserved at refrigeration temperature (4°C) (Rodriguez et al., in preparation) until their analysis. 94Additionally, data raining (Dirección de Hidráulica de Entre Ríos) and, Gualeguaychú river hydrometric 95level (Prefectura Naval Argentina) were registered as complementary information.
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Water quality of the urban lagoon 96 97Physico-chemical and bacteriological tests 98Phosphorous 99Total phosphorus (TP) were determined in unfiltered samples which were digested by heat in an acid 100medium (APHA-AWWA-WPCF, 2013). Soluble reactive phosphorus (SRP) were determined in filtered 101samples with a filter of 0.45 μm, and fixed with 50% Transeau solutionm (APHA-AWWA-WPCF, 2002). Both, TP and SRP, were measured for a 102duplicate by stannous chloride method using spectrophotometer (UV-VIS ZUZI 4211/50) at 690 nm 103(APHA-AWWA-WPCF, 2013). Previously, a calibration curve was performed in the range 0-1000 104expressed as µgP-PO43− /L. 105 106Chemical oxygen demand 107Chemical oxygen demand (COD) was determined in unfiltered samples which were digested by heat in an 108acid medium by reflux closed (APHA-AWWA-WPCF, 2013). Samples were measured for a duplicate by 109spectrophotometric method (UV-VIS ZUZI 4211/50) at 600 nm (APHA-AWWA-WPCF, 2013). 110Previously, a calibration curve was performed in the range 20-900 expressed as µgO 2/L. 111Chlorophyll-a 112Chlorophyll-a (chl-a) was determined accordance with Crettaz-Minaglia et al. (2017) using a 113spectrophotometer (UV-VIS ZUZI 4211/50) after extraction with 100% methanol, at 665 and 750 nm 114before and after acidification with 1N HCl, according to the technique of Marker, Crowther and Gunn, 115(1980). The concentration of chl-a was expressed in µg/L. 116 117Total mesophilic aerobic and coliforms bacteria 118Total mesophilic aerobic bacteria (TMAB) were determined by the method of the fluid plate (APHA119AWWA-WPCF, 2013). Serial dilutions of each sample were made and plated for duplicate on agar for 120plate count (Britania, Rodriguez et al., in preparation) for counting between 30-300 colonies (APHA5
Water quality of the urban lagoon 121AWWA-WPCF, 2013). Plates were incubated for 48 hours at 35°C±1°C in dark stove (APHA-AWWA122WPCF, 2013) and the colonies number was multiplied by the dilution factor and reported as colony 123forming units (CFU)/100 ml (Derlet Ger, Richards, & Carlson, 2008). 124Furthermore, total coliforms (TC) were measured by a method multiple tubes (APHA-AWWA-WPCF, 1252013). Lactose-fermenting colonies from MacConkey (Britania) broth were presumed to be total coliform 126bacteria and were subject to further testing (Derlet et al., 2008). Serial dilutions of each water sampling 127were made and put in tubes for a duplicate (Rodriguez et al., in preparation). They were incubated for 48 128hours at 35°C±1°C in dark stove (APHA-AWWA-WPCF, 2013). Positive tubes were recorded which 129presented gas inside the Durham bells and a color change from purple to yellow (Rodriguez et al., in 130preparation). The concentration of TC was expressed in MPN.100mL -1. 131 132Micro-phytoplankton 133Samples were observed with an optical microscope Olympus® at 40-100 X and the micro-phytoplankton 134was classified up to the gender taxonomic level following specific keys of each group according to 135Gianello et al. (2017): Komárek, Fott and Huber-Pestalozzi (1983) for Chlorophyceae, Komárek and 136Anagnostidis (1999, 2005) for Cyanobacteria, Krammer and Lange-Bertalot (1991) and, Zalocar137Domitrovic and Maidana (1997) for Bacillariophyceae, and Tell and Conforti (1986) for Euglenophyceae. 138 139Data analysis 140Field data were analyzed with PAST (Paleontological Statistic) (Hammer, Harper & Ryan., 2001) and 141Systat Software Inc® version 12.0. Descriptive statistics were used to characterize the variability of 142physical-chemical and bacteriological parameters. Shapiro Wilks normality test was carried out to data 143and Kruskall-Wallis with significance level p < 0.05 and very significance level p
