Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina)

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Original Research Article

Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina) Jorge E. Marcovecchio a,b,c,g,*, Silvia G. De Marco d,b,e, Fiorella Magani h, Carla V. Spetter a,f, M. Ornela Beltrame b,d, Jose´ L. Cionchi b a

Instituto Argentino de Oceanografı´a (IADO – CONICET/UNS), CCT-CONICET-BBlanca, Bahı´a Blanca Argentina Fac. de Ingenierı´a, Universidad FASTA, Mar del Plata, Argentina Universidad Tecnolo´gica Nacional, Facultad Regional Bahı´a Blanca (UTN-FRBB), Bahı´a Blanca, Argentina d Fac. de Cs. Exactas y Naturales, Univ. Nac. de Mar del Plata (FCEyN – UNMdP), Mar del Plata, Argentina e Instituto de Investigaciones Marinas y Costeras (IIMyC) (UNMdP-CONICET), Argentina f Departamento de Quı´mica, Universidad Nacional del Sur (UNS), Bahı´a Blanca, Argentina g Academia Nacional de Ciencias Exactas, Fı´sicas y Naturales (ANCEFN), Av. Alvear 1711, 4to Piso, 1014 Ciudad Auto´noma de Buenos Aires, Argentina h University of Miami, Miami, FL, USA b c

A R T I C L E I N F O

A B S T R A C T

Article history: Received 14 March 2018 Received in revised form 4 December 2018 Accepted 16 April 2019 Available online xxx

Estuaries are transitional systems that link both land and oceans, with particular dynamics regulated by their own characteristics. The main aim of the present study was the assessment of the effects generated by a strong dry period on the distribution of inorganic nutrients and biological production within Mar Chiquita coastal lagoon, comparing this information with that from periods of precipitation regularly conducted. For this study we selected Mar Chiquita coastal lagoon and analyzed a 20-year data series for concentration and distribution of physical and chemical parameters, in particular salinity, inorganic nutrients (i.e. dissolved inorganic nitrogen, phosphate, silicate) and photosynthetical pigments (i.e. chlorophyll a). We also evaluated the association between these parameters and climate conditions within the region, and found a strong relationship and very quick response to changes. As a result, we report, for the first time in the region, rainfall as a main driver of biogeochemical processes within the estuarine system. The obtained results allowed us to confirm the clear transference processes between land and oceanic systems, and the role of climate as a driver of the corresponding transference processes. ß 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Keywords: Mar Chiquita coastal lagoon Nutrients Pigments Climate control

1. Introduction

* Corresponding author, Instituto Argentino de Oceanografı´a, IADO CONICET/UNS, Bahı´a Blanca, Argentina E-mail addresses: [email protected] (J.E. Marcovecchio), [email protected] (S.G. De Marco), [email protected] (F. Magani), [email protected] (C.V. Spetter), [email protected] (M.O. Beltrame), [email protected] (J.L. Cionchi).

Estuaries are among the most biologically productive and ecologically important ecosystems on Earth (Martı´nez et al., 2007; Kasai et al., 2010; Barbier et al., 2011). As transition zones between terrestrial and marine environments, waters entering estuaries are influenced by the lands they run over: i.e. agricultural, urban, and industrial (Ba´rcena et al., 2012; de Brye et al., 2013). Differences in the types of land-use can have a dramatic impact on

https://doi.org/10.1016/j.ecohyd.2019.04.005 1642-3593/ß 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

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estuarine environments (Stoate et al., 2009; Rothenberger et al., 2009), as well as on environmental properties and water column nutrients concentration and distribution, which are particularly affected (Broussard and Turner, 2009; Johnson et al., 2009; Struyf et al., 2010). Moreover, the occurrence of a watershed effect (i.e., the regulation of most of the estuarine processes by freshwater–seawater flows balance) has been well documented (Latimer and Charpentier, 2010; Wetz et al., 2011), and hence also the characterization of an estuarine condition (Moore and Shaw, 2008; Falco et al., 2010). The above could be framed in updated theoretical concepts on function and management of estuaries as reported in the comprehensive review by Elliott and Whitfield (2011), which includes a deep reinterpretation of the main paradigms on this kind of environment (i.e.: ‘‘(i) an estuary is an ecosystem in its own right but cannot function indefinitely on its own in isolation and that it depends largely on other ecosystems, possibly more so than do other ecosystems; (ii) estuaries are more influenced by scale than any other aquatic system; (iii) hydromorphology is the key to understanding estuarine functioning but always influenced by salinity; (iv) although estuaries behave as sources and sinks for nutrients and organic matter, in most systems allochthonous organic inputs dominate over autochthonous organic production; (v) estuaries are physico-chemically more variable than other aquatic systems; (vi) estuaries are systems with low diversity/high biomass/high abundance and their ecological components show a diversity minimum in the oligohaline region; (vii) estuaries have more human-induced pressures than other systems; and (viii) estuaries provide a wider variety of ecosystem services and an increased delivery of societal benefits than many other ecosystems’’) (Elliott and Whitfield, 2011). In addition, climate has also been reported as one of the main drivers of estuaries’ environmental conditions ˜ o and Boyer, 2010; Gillanders et al., 2011). (Bricen However, the effect that drought has on estuarine waters which flow from different land use is largely unknown (Cotrim Marques et al., 2007; Elsdon et al., 2009). Consequently, and keeping in mind that freshwater flowing into estuaries is coming from different origins such as runoff, rainfall or groundwater (de Castro et al., 2004; Davis et al., 2005), the water quality and ecology of estuaries is likely to be impaired (Whitehead et al., 2009). Mar Chiquita coastal lagoon is unique within the coastal system of Buenos Aires Province (Argentina), and has been the subject of a number of geological, climatic, biological, chemical, and environmental studies for several decades (i.e. Lanfredi et al., 1981; Fasano et al., 1982; Marcovecchio et al., 2006; Hassan et al., 2011). Both hydrographical and physical–chemical characteristics of this environment have been reported (i.e., Anger et al., 1994; Freije et al., 1996; Marcovecchio et al., 1997), as well as data on seasonal variations of its hydrographical parameters (Marcovecchio et al., 2006). The main aim of the present study was the assessment of the effects generated by a strong dry period on the distribution of inorganic nutrients and biological production within Mar Chiquita coastal lagoon, comparing this

information with that from periods of precipitation regularly conducted.

2. Materials and methods 2.1. Description of the study area Mar Chiquita coastal lagoon is located between 378330 – 378430 S and 578150 –578300 W, on the Atlantic coast of Buenos Aires Province, 32 km north-east of Mar del Plata city, in Argentina (Fig. 1). This environment has been opportunely declared a Biosphere Reserve under the UNESCO Man & Biosphere Program (MAB). The lagoon has an area of 60 km2, with a tributary basin close to 10,000 km2. Its shape is irregular, and its bottom topography very smooth, reaching a maximum depth of 1.50 m (Lanfredi et al., 1981), with no vertical stratification on the water column during the year. The lagoon is connected to the sea through an elongated inlet channel of approximately 6 km length and more than 200 m width. The influence of freshwater is more important than that of seawater (salinity range: 1.3– 28.75; Marcovecchio et al., 2006) due to the fact that the lagoon’s main input is the continental drainage, which collects rainwater from a large basin, including the Tandilia orographic system. Average rainfall for this area is about 900 mm yr1, with a homogeneous distribution throughout the year; even though torrential rainfall is usually recorded during the winter and spring seasons (from June to October) (Table 1). For the present study, four different scenarios have been considered: two periods with more intense ðx ¼ 959 mm yr1 Þ and less intense precipitation ðx ¼ 919 mm yr1 Þ, as well as an extremely wet year ðx ¼ 1198 mm yr1 Þ and one unusually dry ðx ¼ 528 mm yr1 Þ. Moreover, the role of phreatic reservoir which regulates the lagoon water level and the standard meteorological conditions of the area has been reported, so that an increase in the water level within the reservoir regulates not only the depth of the lagoon but also the surface of water mirror, and consequently, the rainfall within the area (Fasano et al., 1982). Thus, the phreatic reservoir acts as a climate regulator: an increase in the area of the lagoon is coincident with a significant increase in precipitations within the region (Fasano et al., 1982). This environment function as a transitional one, which receives large amount of inorganic nutrients from neighboring terrestrial ecosystems throughout the year (Marcovecchio et al., 2006). The combination of these particular conditions (i.e., high nutrient availability, reduced depth, calm conditions within the water body, restricted water circulation, and homogeneity in the water column) drives biological production at a higher rate than in adjacent coastal marine environment (Perillo et al., 2006). 2.2. Sampling and data analysis Six sampling stations were located along the coastal lagoon, representing different conditions within this environment (Fig. 1). The key characteristics of each sampling station were:

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

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Fig. 1. Location of Mar Chiquita coastal lagoon, and corresponding sampling stations.

Table 1 Historical monthly precipitation within Mar Chiquita coastal lagoon region (information kindly provided by Centro de Informacio´n Meteorolo´gica, Servicio Meteorolo´gico Nacional, Argentina). Analyzed period

1901–1980 average 1981–2007 average 1984 2009 2010–2015 average

Monthly precipitation (mm) Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Annual average

88 110 90 40 96

78 67 96 32 82

112 90 102 46 99

98 76 94 41 91

77 80 97 55 83

88 41 76 49 67

64 56 87 57 66

44 55 86 49 56

61 54 95 32 67

60 110 136 49 89

75 81 111 54 80

114 99 128 34 104

959 919 1198 528 980

- Station #1 was located within the lagoon, at the outlet to the ocean. - Station #2 was close to the freshwater discharge of Cangrejo Creek (where several streams drain). - Station #3 was close to a large bridge crossing the lagoon, acting as a physical barrier which traps sediments and impairs tidal penetration to the inner area. - Station #4 was close to a large wetland area dominated by burrowing crabs. - Station #5 was close to a major livestock farming area. - Station #6 was in an important area for sport fishing. - Station #7 was in the inner part of the lagoon. In addition, samples were also obtained within the most important streams which drain to the costal lagoon (Fig. 1). They are: -

de las Gallinas Stream Grande Stream Vivorata´ Stream Sotelo Stream Channel N85 Channel N87

Two sampling points were settled in each station: one in the upstream of each stream (to measure the water quality far to the lagoon) and the other one in the outlet of

the stream into the lagoon (to measure the integrated load within the corresponding watershed). In this sampling net within Mar Chiquita costal lagoon and its watershed we measured the spatial and seasonal variation of eight hydrographical parameters: temperature, conductivity/salinity, nitrate, nitrite, phosphate and silicate in water; and chlorophyll a and phaeopigments in suspended particulate matter. In all cases measurements were carried out at subsurface level as well as corresponding water sampling, considering the shallow depth of the lagoon throughout the year and the fact that stratification was never recorded within this system. Sampling was developed along 21 years (1994 to 2005), with seasonal frequency. In situ water temperature and conductivity/salinity were measured using a Horiba1U-10 multisensor device, previously calibrated against traditional standardized methods (APHA-AWWS-WEF, 1999). Water samples were obtained using pre-washed polycarbonate Van Dorn sampling bottles in order to determine nutrient and pigment concentrations. Sub-samples for nutrient determination were filtered and stored in plastic bottles at 20 8C, while those for pigments were vacuum filtered through Whatmann GF-C glass fiber filters and were stored in a freezer (20 8C) until laboratory analysis. Inorganic nutrients were determined following methodologies

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reported by Treguer and Le Corre (1975) for nitrate, by Grasshoff et al. (1983) for nitrite, by Eberlein and Kattner (1987) for phosphate, and by Technicon1 (1973) for silicate. In all cases, determinations were performed using a Technicon1 AA-II four channel auto-analyzer. Concentrations of chlorophyll a and phaeopigments in suspended particulate matter were measured according to Lorenzen and Jeffrey (1980), and corresponding analyses were performed by means of a Shimadzu 210-A UV-VIS spectrophotometer. Calibration curves and blanks were built up using analytical grade reagents. Analytical quality (AQ) control was carried out analyzing highly pure specific solutions (i.e., nitrate, nitrite, etc.) as well as calibrating the instruments for field measurements using validated methods. Statistical analyses were done using analysis of variance (ANOVA) test, mean values assessment (Tukey’s test), correlation analysis and single linear regression analysis (Sokal and Rohlf, 1981). All statistical tests were performed using the Statistica software package (version 7.1). Significance was set at p value <0.05.

average rainfall recorded for this area is close to 900 mm yr1 (Table 1). 2009 was an extremely dry year, with an average rainfall close to 530 mm yr1 (Table 1). This climatic condition caused a completely different salinity distribution pattern within the coastal lagoon. In the same three identified areas described before, the distribution trend was significantly different. The first one (the marine area) presented a salinity range from 31.15 to 27.6, but in this case represented 71% of the coastal lagoon surface; the salinity in the second area (estuarine) varied between 19.95 and 12.35, and represented 25.5% of the coastal lagoon surface; and, finally, in the third area (inland water system) salinity varied from 7.3 to 4.1, representing 3.5% of the coastal lagoon surface (Fig. 2b). During the next analyzed period (2010–2015) the relative percentages of coastal lagoon surface as represented by each of the abovementioned areas were approximately 12.7%, 11.5% and 75.8% respectively (Fig. 2c), with corresponding salinity ranges of 30.7– 27.3, 17.15–10.3, and 5.2–1.9 respectively. 3.2. Inorganic nutrients concentration and distribution

3. Results During the last twenty years comprehensive studies on environmental conditions of Mar Chiquita coastal lagoon and its corresponding watershed have been carried out, including the measurement of temperature, salinity/ conductivity, pH, dissolved oxygen, turbidity, inorganic nutrient concentrations (i.e. nitrate, nitrite, ammonium, phosphate and/or silicate) in water, and chlorophyll a, phaeopigments and particulate organic matter in suspended particulate matter – SPM – within this aquatic system (Freije et al., 1996; De Marco et al., 2005; Marcovecchio et al., 2006). Most of the processes related to biogeochemical dynamics within this system are natural ones (i.e. organic matter mineralization, physical mixing, weather influence) and only a few ones are anthropic (agriculture and livestock activities) since there are no large human settlements within the area. 3.1. Fluctuation of salinity levels within the coastal lagoon During the study period, salinity was a very sensitive water parameter within Mar Chiquita coastal lagoon system, which significantly responded to environmental changes (i.e. climatic, hydrodynamic). During the first (and longer) studied period – 1994–2007 – a clear salinity gradient was recorded, with values ranging from 29.15 (in the outermost sampling station close to the sea) to 2.8 (in the innermost one) (Fig. 2a). We identified three different areas: (i) an external area where salinity ranged from 29.15 to 27.75, which functioned as a coastal marine system (representing 12% of the coastal lagoon surface); (ii) an intermediate area with salinity varying from 19.6 to 10.85, functioning like an estuarine system (representing 23% of the coastal lagoon surface); and (iii) an internal area where salinity varied from 9.15 to 2.8, and had the characteristics of an inland water system (representing 65% of the coastal lagoon surface) (Fig. 2a). Worth noting,

We analyzed the concentration and distribution patterns of inorganic nutrients (i.e. dissolved inorganic nitrogen as the addition of nitrate, nitrite and ammonium, DIN = NO3 + NO2 + NH4+; soluble reactive phosphorous, PO43; and, total dissolved silicate, SiOx) within the three aforementioned areas at Mar Chiquita coastal lagoon during the considered periods. This allowed us to characterize each of them as well as their relationship with corresponding environmental conditions. For DIN levels and distribution during the first studied period (1994–2007) each area showed: (i) DIN concentrations of 2.3  1.1 mM in the marine area, with a variation range of 0.2–3.65 mM; (ii) DIN levels in the estuarine area varied between 1.2 and 18.15 mM, with average values 11.6  3.7 mM; and (iii) within the inland area DIN values were between 14.6 and 53.1 mM, with mean values of 39.9  7.5 mM (Fig. 3a). DIN mean values between 1994 and 2007 were significantly different (p < 0.05) among the three described areas within the coastal lagoon. In the second analyzed period (2009) the same distribution pattern was identified (higher DIN levels in the inland waters, medium in the estuarine area and lower in the marine one) but with quite different concentrations: 92–185 mM, 19–62 mM, and 2.1–11.2 mM respectively (Fig. 3b). In this case, the recorded DIN concentrations were also significantly different (p < 0.05) among the three areas. Finally, in the third period (2010–2015) we observed a different distribution trend: (i) both the inland and the estuarine areas presented a similar DIN distribution, with values varying from 19 to 59 mM, with slightly higher but not statistically significant DIN levels in the inland area (p > 0.05); (ii) the coastal marine showed DIN levels from 0.15 to 4.25 mM (Fig. 3c). The comparative analysis of these results has showed significant differences (p < 0.05) among DIN values of the inland and estuarine areas with respect to those from the marine one. In the case of phosphate, the values distribution was highly scattered along the studied salinity gradient within

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Fig. 2. Salinity distribution within Mar Chiquita coastal lagoon during the studied periods. a. 1994–2007; b. 2009; c. 2010–2015.

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Fig. 3. Dissolved inorganic nitrogen (DIN) (mM) distribution within Mar Chiquita coastal lagoon during the studied periods. a. 1994–2007; b. 2009; c. 2010–2015.

the coastal lagoon, regardless of the area which was considered (Fig. 4a–c). On the other hand, PO43 concentration varied between 0.15 and 2.65 mM, with similar levels found between the three considered periods, and even though concentrations from 2009 seemed to be slightly lower than those from the other two lapses (Fig. 4), no significant differences (p > 0.05) were found. Finally, DSi levels presented different distribution trends within each of the studied periods. In the first period (1994–2007) we found that: (i) the highest DSi concentrations were recorded in the inland area, with values varying from 200 to 325 mM; (ii) both, the estuarine and the coastal marine areas showed similar levels of DSi, which ranged between 95 and 215 mM, and with a similar distribution trend (Fig. 5a). No significant differences (p > 0.05) were found between DSi levels between the considered areas in Mar Chiquita. The distribution pattern of DSi during 2009 was different,

with the highest values in the inland waters (140– 270 mM), and lowest ones in both the estuarine and the marine areas (45–150 mM), with highly significant differences (p < 0.05) between the first and the other two (Fig. 5b). Finally, during the third analyzed period (2010– 2015) a similar and fully scattered distribution trend of DSi concentrations was found for the three studied areas within Mar Chiquita coastal lagoon, with values ranging from 145 to 315 mM (Fig. 5c). In this last period, no significant differences (p > 0.05) were found among DSi levels of the three considered areas of the coastal lagoon. 3.3. Chlorophyll a distributions pattern We analyzed chlorophyll a levels in the first evaluation period (1994–2007) and found that: (i) the highest chlorophyll a concentrations were in the inland waters, ranging between 32.5 and 60.5 mg L1 and with a mean

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

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Fig. 4. Dissolved phosphate (PO43) (mM) distribution within Mar Chiquita coastal lagoon during the studied periods. a. 1994–2007; b. 2009; c. 2010–2015.

value of 50  7.85 mg L1; (ii) the estuarine area presented a chlorophyll a average concentration of 27.5  5.4 mg L1, with a range from 18.3 to 33.6 mg L1; and (iii) chlorophyll a levels in the marine area ranged between 1.1 and 17.35 mg L1, with a mean value of 7.4  4.15 mg L1 (Fig. 6a). Mean values were significantly different for the three considered areas within the coastal lagoon (p < 0.05). The analysis that corresponds to 2009 period showed the following trend: (i) one data set including samples of inland waters and the innermost estuarine area with chlorophyll a values ranging from 40.6 to 114.5 mg L1, and a mean value of 77.4  11.7 mg L1; (ii) another one including samples of the outermost estuarine area and the marine one, with chlorophyll a average value of 29.4  8.75 mg L1, and a corresponding range of concentrations from 1.7 to 44.3 mg L1 (Fig. 6b). In this case, chlorophyll a mean values were significantly different (p < 0.05).

Finally, for the period between 2010 and 2015 we found that: (i) the inland waters and the innermost estuarine area has showed a chlorophyll a mean concentration of 40.6  4.15 mg L1, with a range of values between 19.5 and 52.7 mg L1; and (ii) the outermost estuarine and the marine areas had a range between 1.1 and 21.3 mg L1, and showed an average concentration of 11.3  4.6 mg L1 (Fig. 6c). Significant differences (p < 0.05) were observed between chlorophyll a mean values. In addition, chlorophyll a concentrations were significantly higher (p < 0.05) in samples from 2009 than those corresponding to the other two periods. Other physical–chemical parameters were also considered as potential tracers of the variation that occurs in the mixing zone (i.e. dissolved oxygen, pH, or turbidity). Even though their analysis has not showed clear trends, it grants deeper future valuation.

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

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Fig. 5. Dissolved silicate (DSi) (mM) distribution within Mar Chiquita coastal lagoon during the studied periods. a. 1994–2007; b. 2009; c. 2010–2015.

4. Discussion Dynamics and performance of the aquatic environments, particularly those transitional ones connecting large catchments with the coastal marine system, are fully influenced by environmental conditions. Among these, it has been shown that weather conditions affect the ecosystems, and the meteorological phenomena modify the characteristics of the environment at different scales (Smith and Smith, 2001). Consequently, different authors have stated that both the intensity and frequency of meteorological events could significantly modify physical and chemical scenarios within aquatic systems (mainly estuaries and wetlands), which in turn would result in an alteration of the associated biological assemblages (e.g., Wetz and Yoskowitz, 2013; Liu et al., 2013). In order to increase knowledge on this topic, Mar Chiquita coastal lagoon was our case study, and we analyzed two decades of data on environmental together

with recorded changes in the chemical conditions of the system. One of the highlights in the present study was the variations on the physical dynamics within the system, represented by changes in both the salinity gradient intensity and location. Moreover, during the period 1994– 2007, an equilibrium condition was observed which included the three involved areas of this transitional system (i.e. inland, estuarine, marine) (Fig. 2a). It is a very well documented fact that the composition of both surface and groundwater depends on natural factors (i.e. geological, topographical, meteorological, hydrological and biological properties) (Park et al., 2010; Wu and Kuo, 2012), characteristics of the drainage basin (Stro¨mqvist et al., 2012), and that also varies with seasonal differences in continental drainage (i.e. runoff volumes, water levels and weather conditions) (Kayhanian et al., 2012). The data presented in this study clearly show that variation in rainfall within Mar Chiquita catchment fully governed salinity distribution in the system, and hence, the ionic

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Fig. 6. Chlorophyll a (Chl a) (mg L1) distribution within Mar Chiquita coastal lagoon during the studied periods. a. 1994–2007; b. 2009; c. 2010–2015.

strength acting on the whole environment. The first salinity distribution status as recorded in Mar Chiquita (1994–2007) seemed to be the historical one (or at least the one most frequently described as typical of this estuarine system); in the same way, similar salinity distribution has been opportunely reported by Olivier et al. (1972a, b), Spivak et al. (1991), Gime´nez (2003), and Marcovecchio et al. (2006). Even though the geographical extension of each identified area was not particularly considered in those previous studies, all of them have reported the occurrence of the three described areas (i.e. marine, estuarine and inland), and the corresponding range of salinity values were also similar to those in the present study. However, a particular event allowed us to deeply understand the role of climatic condition in the salinity distribution within the coastal lagoon system: the fact that 2009 was an extremely dry year. The meteorological records of this year (Centro de Informacio´n Meteorolo´gica, Servicio Meteorolo´gico Nacional, Argentina)

showed rainfalls of 528 mm yr1, when the usual historic average is higher than 900 mm yr1 (Table 1). This particular condition determined the occurrence of a shock in the salinity distribution within the system, which looked largely like a marine and estuarine, highly and significantly reducing the inland area (Fig. 2b). The situation returned to a normal distribution in the following years, when rainfall also reached its historical level (Fig. 2c). This significant variation in the salinity distribution pointed out the importance of climatic characteristics as a regulator of the system structure, and it highlights the pressure that continental water produces over seawater when its volume is large enough. In this way, the continental discharge on the coastal lagoon (i.e. continental runoff, streams drainage, rainfall) would work like a ‘‘hydraulic plug’’ which dams seawater toward the coast, inhibiting its access to the inner zone. In this sense, several authors have described this kind of relationship between water masses whose imbalance determine the final condition of the studied system. Various

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authors (Mercado and Go´mez, 1998; Gentile and Gonza´lez, 2001; Pizarro et al., 2007) have investigated the effect of the sudestada in Argentina, which is a short-term hydrometeorological phenomena associated with the occurrence of winds from the southeastern quadrant which press one water mass over another. The aforementioned authors have studied the effect of the sudestada on the Parana´ River, La Plata River, and Luja´n River respectively, concluding in all the cases that this sustained wind produced significant changes in each studied system. This phenomenon places a strong pressure on seawater against the river ones, and could generate large floods resulting in significant risks for cities and human populations. Moreover, Garcı´a and Mechoso (2005) reported that the sudestadas at La Plata River strongly affect the normal river drainage, modifying the physical, chemical, and biological characteristics of the whole system. Unfortunately, there is little information about the effect of rainfall on the dynamics of temperate aquatic systems. This kind of processes, as previously described, are quite usual within tropical systems, where strong contrasts in seasonal rainfall often lead to episodic events manifested as large monsoonal freshwater flows (i.e. Yin, 2002), but extremely scarce in temperate ones. In addition, it is well documented that changes in the salinity gradient causes variation in the ionic strength within the aquatic system (Pawlowicz et al., 2010). In this sense, Brunk et al. (1997) reported that increasing ionic strength within estuaries determines the increment of overall sorption rates with the consequent retention of substances (i.e. pollutants, organic matter) within sediments and/or suspended particulate matter (SPM). Similar results have been obtained by Tremblay et al. (2005) studying the behavior of dissolved humic substances (organic matter) in estuarine systems. Moreover, Jeon et al. (2011) studied the influence of salinity and organic matter on the distribution coefficient (Kd) of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in a brackish water–clay system, concluding that enhancement of sorption of PFAs to particulate matter at high salinity values could evoke potential risks to benthic organisms in estuarine areas. This concept is quite important for our study considering that the significant change in the salinity gradient recorded in Mar Chiquita coastal lagoon means that the ionic strength has also widely varied along the evaluated periods. And, considering that different pollutants (i.e. trace metals, persistent organic pollutants) have been opportunely recorded within this system (De Marco et al., 2006; Beltrame et al., 2009, 2010a; Menone et al., 2000, 2001) and organic matter concentrations (Marcovecchio et al., 2006; Beltrame et al., 2008), the risk of variation within toxicity levels of these compounds (i.e. increases/decreases) must be considered. This fact was explicitly demonstrated by Beltrame et al. (2010b) who developed a Zn toxicity bioassays using the burrowing crab Neohelice granulata from Mar Chiquita coastal lagoon as an indicator organism, demonstrating that this metal was more toxic at a lower salinity (i.e. 5 psu) than at a higher one (i.e. 30 psu). This different structural scenario also impacts on the distribution of inorganic nutrients along the areas of the coastal lagoon, as was mentioned before. Therefore, the

DIN levels were always maximum in the inland area, and this fact is presumably related to its continental origin and washed out by runoff processes (Brodie et al., 2012; Bouwman et al., 2013). DIN concentrations in the inland area recorded during the 1994–2007 and 2010–2015 periods were quite similar, and in agreement with previous reports for the coastal lagoon (i.e. Freije et al., 1996; De Marco et al., 2005; Marcovecchio et al., 2006). This area of high DIN levels along the whole studied periods could be considered the ‘‘ROFI’’ (region of freshwater influence) according to Statham’s (2012) proposal. This distribution showed the same trend, but increased the levels significantly during 2009, when DIN levels were approximately three times higher than those previously mentioned (Fig. 3). In this case, multiple factors should be considered: the origin of these nutrients within the watershed as previously mentioned, and the freshwater pile up produced by the pressure of both marine and estuarine waters over the inland ones, which keeps off the freshwater discharge, and consequently, the dilution of the DIN. This process has been reported before; DIN levels within considered streams of the region presented similar values than historical ones (De Marco et al., unpublished data), and considering that coastal marine waters´ DIN contents are significantly lower (Piola and Falabella, 2009) the overload of these nutrients through this mechanism is clearly highlighted. Equivalent processes have been opportunely reported by Hessen et al. (2010) for the Ob and Yenisey estuaries, in the Norwegian Arctic Sea; and by Statham (2012) who reviewed this phenomenon within numerous estuaries all over the world. Moreover, inorganic nitrogen nutrients could have different origins and all of them could simultaneously occur within the coastal lagoon. It is important also to consider nutrients washed out from soils by runoff processes (Kirkby, 2010), provided through rainfall (Adame et al., 2010), released from organic matter mineralization processes (Weston et al., 2011), transported by rivers, creeks and streams (Seitzinger et al., 2010) and included in anthropic discharges (Carvalho Aguiar et al., 2011). In this sense, Violaki et al. (2010) strongly highlighted the role of rainfall as carrier of DIN to the land and/or aquatic ecosystems, while Perakis and Hedin (2002) produced a comprehensive overview on nitrogen cycling within the environment, highlighting that inorganic nitrogen nutrients are extremely mobile forms, and that their loss from soils (even unpolluted ones) can generate important long-term effects on productivity and carbon storage in temperate forest ecosystems. On the other hand, the region of Mar Chiquita coastal lagoon catchment has been reported as an environment with a very high nitrogen load, which – in fact – never reaches total depletion of this element’s compounds (De Marco et al., 2005; Marcovecchio et al., 2006). Several authors have suggested that the streams studied may be chronically nutrient-enriched systems (Feijoo´ and Lombardo, 2007; Feijoo´ et al., 2011; Amucha´stegui et al., 2016), besides describing a strong relationship between dissolved inorganic nutrient concentrations and land-use, mainly with those N-based compounds. Also, the high content of nutrients (mainly those of nitrogen) within soils of SE Buenos Aires Province has been opportunely reported

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(Grondona et al., 2013; Giletto and Echeverrı´a, 2013). Moreover, a significant input of nutrients is incorporated into the soils through fertilization, considering the whole area is mainly directed to both agriculture and cattle raising activities (Barral and Maceira, 2012). In the case of dissolved phosphate, a different condition was observed: the levels of PO43 did not significantly vary between the three considered periods, even though the value distribution was less scattered during the dry year (2009) than on the other two (Fig. 4). This point should be related to the observed values which were not different along the studied salinity gradient (i.e. freshwater– estuarine water–marine water), and include a similar range of concentrations from the regional streams (Beltrame, 2009) to the estuarine and marine ones (De Marco et al., 2005; Marcovecchio et al., 2006). Even though the same nutrient sources previously mentioned for N compounds also exist for P ones, it must be highlighted that most of the phosphorous can be retained and trapped by soils (Fan and Guo, 2010; Sharpley et al., 2013), and only the physical–chemical conditions of the system govern not only its release but also the speed of the process (Shen et al., 2011). This is a very important point, which supports the fact that the distribution of PO43 has not varied within the present study, neither when freshwater discharge pushes on the estuarine and marine environments, nor in the scenario of full dominance of marine and brackish water in the coastal lagoon. The analysis of dissolved silicate showed the terrestrial origin of these compounds, which presented their highest concentrations in the freshwater domain, a transitional zone within the estuarine area, and a dilution zone in the marine one (Fig. 5). This scheme remained the same during the so-called normal periods (or at least, more usual periods), which even showed differences in the magnitude of the transported silicate compounds. However, during the dry period studied this situation was modified, presenting a very complex transfer from the freshwater to the estuary/ sea, and generating the dilution zone very close to the discharge itself. This modification has been attributed to the push of brackish/marine waters on the continental area which hinders the usual outflow into the coastal lagoon. These high DSi levels in the innest area could be explained considering both the retention of these compounds through previously reported mechanisms, as well as the contribution of DSi from seawater that has considerable value in the associated coastal zone (Perillo et al., 2006). In addition, this kind of process has been clearly described in studies of submarine groundwater discharges (SGD) within the coastal zone (i.e., Du¨rr et al., 2011; Knee and Paytan, 2011; Liu et al., 2012) but are very scarce or even nule in studies along salinity gradients like estuarine systems (i.e. Falco et al., 2010; Carbonnel et al., 2013), which enlights the contribution of the present study. When the biological production of the coupled system (i.e. catchment + coastal lagoon + coastal zone) was analyzed, we observed that this environment was productive (and even highly productive) along the whole year according to the corresponding chlorophyll a values recorded (Fig. 6). This situation was fully in agreement with previous records as those by De Marco et al. (2005),

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Marcovecchio et al. (2006) or Beltrame (2009), who have described the coastal lagoon as a continuously productive system. The inner area of the system, meaning the freshwater zone and the innermost region of the estuary, proved to be the highest productive ones during both normal evaluated periods (1994–2007 and 2010–2015), with a clear decrease of chlorophyll a values along the estuarine area, and the minimum levels within the marine coastal zone. Similar trends in chlorophyll a distribution have been reported by Cloern and Jassby (2009) who studied chlorophyll a time series from North Inlet, Biscayne Bay, Chesapeake Bay, Ringkøbing Fjord and Tampa Bay, all of them in the northern hemisphere. Pe´rez-Ruzafa et al. (2011) studied seven European coastal lagoons and also reported similar conclusions on chlorophyll a as indicator of phytoplankton production. Moreover, Cloern et al. (2014) presented an extensive review on primary production on estuarine/coastal ecosystems where a similar process to the one reported here was described for different coastal lagoons. This kind of distribution has been described in other environments (i.e. Mongin et al., 2011), and in most cases, the freshwater influence area demonstrated to be more productive than the saline one (Neveux et al., 2015). This fact can be supported by several points: (i) freshwaters have a higher level of inorganic nutrients considering they have land origin (Staehr et al., 2012); (ii) freshwater areas are usually less deep and calmer waters than marine ones (Bakun, 2010); and (iii) the stability of the freshwater column is higher than the marine one (Faye et al., 2011). These factors produce an environmental scenario which favors the biological production of freshwater influenced systems against marine ones. Moreover, this production decreased when salinity increased, and it is important to point out that recorded levels were high along the whole system in comparison with other marine coastal ones (Philippart et al., 2010; Souchu et al., 2010). Nevertheless, during the dry period, when most of the coastal lagoon was salty or at most brackish, the described distribution trend of chlorophyll a levels remained similar, with the maximum values near streams outlet and minimum ones close to the ocean (Fig. 6), but with much higher concentrations (50– 100% higher than in wet periods). What happened in that situation? Nutrients usually discharged from land to the coastal lagoon were retained by the strength of the incoming tide, which stacked them in the bottom of the lagoon producing the extremely high levels of DIN as opportunely recorded (Fig. 3). Within this new scenario, with very high nutrients available, relatively calm waters and low depth phytoplankton have extraordinary chances to increase, producing the observed phenomenon. In addition, levels of chlorophyll a were also higher in the middle and external areas of the coastal lagoon during the dry period than in the wet ones, and this is presumably linked to the redistribution that occurs with the entry and exit of the tide, which is why this system has a semidiurnal tide regime (Lanfredi et al., 1981). Finally, the system seemed to regain its normal dynamics when the incoming freshwater volume increased significantly. This fact clearly showed that climate is one of the drivers of the biogeochemical processes that regulate the

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biological production within this complex system, which demonstrated to be extremely sensitive to changes even in relatively short times. We also compared the results obtained from Mar Chiquita coastal lagoon evaluation (i.e. highest distribution of inorganic nutrients and chlorophyll a in the innest area, high biological production along the whole year, strong dependency on salinity condition) to those reported by other authors in different coastal lagoons in the world. Souchu et al. (2010) assessed 20 lagoons associated to the French Mediterranean, highlighting a strong correlation between inorganic nutrients and chlorophyll a, as well as that both marine and freshwater environments responded in a similar way to nutrient enrichment. In addition, Brito et al. (2010, 2012) studied the Rı´a de Formosa in southern Portugal and concluded that nutrient concentrations – especially nitrogen – was clearly influenced by precipitation, and highlighted the significance of runoff on these levels. Moreover, Aleksandrov (2010) studied both the Kuronian and Vistula lagoons, in Kaliningrad regio´n, in Russia, and focused on nitrogen levels, chlorophyll a concentrations – phytoplankton production, and hydrodynamics characteristics within each of them. These scenarios allowed to describe their corresponding eutrophication levels.

Funding body Authors are fully indebted to CONICET, ANPCyT, UNMdP, UFASTA and IADO - CONICET/UNS for their finantial support to our project during two decades. Acknowledgements The authors are fully indebted with many people who have collaborated to develop this study along 20 years: the staffs from HYAC-FCEyN-UNMdP, LQM-IADO-CONICET/ UNS, Environmental Geology Group (IGCyC-UNMdP) and Ecosystems Group (FI-UFASTA). Also, the Centro de Informacio´n Meteorolo´gica, Servicio Meteorolo´gico Nacional from Argentina has kindly provided meteorological information within the region. Marı´a Juliana Bo´ (IGCyCUNMdP/FI UFASTA) has kindly build up the figures as included within this manuscript. The study was supported through different grants provided by CONICET (National Council for Scientific and Technological Researches, Argentina); ANPCyT (National Agency for Science and Technology Promotion, Argentina); UNMdP (Mar del Plata National University, Argentina) and UFASTA (FASTA University, Argentina) along the considered 20 years.

5. Concluding comments

References

The chance to develop a long term study (20 years) in Mar Chiquita coastal lagoon and its watershed was very advantageous, considering the occurrence of different environmental conditions and the observed variation of associated biogeochemical processes. The results we obtained allowed us to draw several significant conclusions:

Adame, M.F., Virdis, B., Lovelock, C.E., 2010. Effect of geomorphological setting and rainfall on nutrient exchange in mangroves during tidal inundation. Marine & Freshwater Research 61, 1197–1206. Aleksandrov, S.V., 2010. Biological production and eutrophication of Baltic Sea estuarine ecosystems: the Curonian and Vistula Lagoons. Marine Pollution Bulletin 61, 205–210. Amucha´stegui, G., di Franco, L., Feijoo´, C.J., 2016. Catchment morphometric characteristics, land use and water chemistry in Pampean streams: a regional approach. Hydrobiologia 767 (1), 65–79. Anger, K., Spivak, E., Bas, C., Ismael, D., Luppi, T., 1994. Hatching rhythms and dispersion of decapods crustacean larvae in a brackish coastal lagoon in Argentina. Helgoland Marine Research 48, 445–466. APHA-AWWS-WEF (American Public Health Association-American Water Works Association-Water Environment Federation), 1999.In: Standard Methods for the Examination of Water and Wastewater, 20th ed., Washington, DC, USA, p. 541. Bakun, A., 2010. Linking climate to population variability in marine ecosystems characterized by non-simple dynamics: conceptual templates and schematic constructs. Journal of Marine Systems 79, 361– 373. Barbier, E.B., Hacker, S.D., Kennedy, C., Koch, E.W., Stier, A.C., Silliman, B.R., 2011. The value of estuarine and coastal ecosystem services. Ecological Monographs 81 (2), 169–193. Ba´rcena, J.F., Garcı´a, A., Go´mez, A.G., A´lvarez, C., Juanes, J.A., Revilla, J.A., 2012. Spatial and temporal flushing time approach in estuaries influenced by river and tide. An application in Suances Estuary (Northern Spain). Estuarine Coastal and Shelf Sciences 112, 40–51. Barral, M.P., Maceira, N.O., 2012. Land-use planning based on ecosystem service assessment: a case study in the Southeast Pampas of Argentina. Agriculture, Ecosystems & Environment 154, 34–43. Beltrame, M.O., 2009. Dina´mica biogeoquı´mica de nutrientes y metales pesados en ambientes intermareales de la laguna costera Mar Chiquita: potenciales efectos ecotoxicolo´gicos sobre especies claves del ecosistema. In: Tesis Doctoral, Depto.de Biologı´a, Bioquı´mica y Farmacia, Universidad Nacional del Sur (UNS), Bahı´a Blanca (Argentina), p. 259. Beltrame, M.O., De Marco, S.G., Marcovecchio, J.E., 2008. Cadmium and zinc in Mar Chiquita coastal lagoon (Argentina): salinity effects on lethal toxicity in juveniles of the burrowing crab Chasmagnathus granulatus. Archives of Environmental Contamination & Toxicology 55, 78–85. Beltrame, M.O., De Marco, S.G., Marcovecchio, J.E., 2009. Dissolved and particulate heavy metals distribution and regulation in coastal

- The continental system is the main source of inorganic nutrients to the coastal zone. - Different natural and anthropic processes contribute to the nutrients’ budget within this kind of environment. - Climatic system conditions nutrients distribution within the aquatic environment, and this affects the biological production of the system. - The response time of this environment was very short, changing its condition in rainy or dry periods, and returning to its previous condition quickly. - This small scale study is useful to point out that permanent or even long term variations within the climate system would produce severe changes in the biogeochemical cycles within the coastal zone, with a very large number of possible consequences.

Conflict of interest None declared. Ethical statement Authors state that the research was conducted according to ethical standards

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

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ECOHYD-248; No. of Pages 15 J.E. Marcovecchio et al. / Ecohydrology & Hydrobiology xxx (2019) xxx–xxx lagoons. A case study from Mar Chiquita Lagoon, Argentina. Estuarine Coastal and Shelf Sciences 85, 45–56. Beltrame, M.O., De Marco, S.G., Marcovecchio, J.E., 2010a. Influences of sex, habitat and seasonality on heavy metal concentrations within the burrowing crab (Neohelice granulata) from a coastal lagoon in Argentina. Archives of Environmental Contamination & Toxicology 58 (3), 746–756. Beltrame, M.O., De Marco, S.G., Marcovecchio, J.E., 2010b. Effects of zinc on molting and body weight of the estuarine crab Neohelice granulata (Brachyura: Varunidae). The Science of the Total Environment 408, 531–536. Bouwman, A.F., Bierkens, M.F.P., Griffioen, J., Hefting, M.M., Middelburg, J.J., Middelkoop, H., Slomp, C.P., 2013. Nutrient dynamics, transfer and retention along the aquatic continuum from land to ocean: towards integration of ecological and biogeochemical models. Biogeosciences 10, 1–23. ˜ o, H.O., Boyer, J.N., 2010. Climatic controls on phytoplankton Bricen biomass in a sub-tropical estuary, Florida Bay, USA. Estuaries & Coasts 33 (2), 541–553. Brito, A., Newton, A., Tett, P., Ferna´ndes, T.F., 2010. Sediment and water nutrients and microalgae in a coastal shallow lagoon, Ria Formosa (Portugal): implications for the Water Framework Directive. Journal of Environmental Monitoring 12, 318–328. Brito, A., Newton, A., Tett, P., Ferna´ndes, T.F., 2012. How will shallow coastal lagoons respond to climate change? A modelling investigation Estuarine. Coastal and Shelf Science 112, 98–104. Brodie, J.E., Kroon, F.J., Schaffelke, B., Wolanski, E.C., Lewis, S.E., Devlin, M.J., Bohnet, I.C., Bainbridge, Z.T., Waterhouse, J., Davis, A.M., 2012. Terrestrial pollutant runoff to the Great Barrier Reef: an update of issues, priorities and management responses. Marine Pollution Bulletin 65, 81–100. Broussard, W., Turner, R.E., 2009. A century of changing land-use and water-quality relationships in the continental US. Frontiers in Ecology & Environment 7, 302–307. Brunk, B.K., Jirka, G.H., Lion, L.W., 1997. Effects of salinity changes and the formation of dissolved organic matter coatings on the sorption of Phenanthrene: implications for pollutant trapping in estuaries. Environmental Science & Technology 31, 119–125. Carbonnel, V., Vanderborght, J.-P., Lionard, M., Chou, L., 2013. Diatoms, silicic acid and biogenic silica dynamics along the salinity gradient of the Scheldt estuary (Belgium/The Netherlands). Biogeochemistry 113, 657–682. Carvalho Aguiar, V.M.D., Baptista Neto, J.A., Marclei Rangel, C., 2011. Eutrophication and hypoxia in four streams discharging in Guanabara Bay, RJ, Brazil, a case study. Marine Pollution Bulletin 62, 1915–1919. Cloern, J.E., Jassby, A.D., 2009. Patterns and scales of phytoplankton variability in estuarine-coastal ecosystems. Estuaries and Coasts 33, 230–241. Cloern, J.E., Foster, S.Q., Kleckner, A.E., 2014. Phytoplankton primary production in the world’s estuarine-coastal ecosystems. Biogeosciences 11, 2477–2501. Cotrim Marques, S., Miranda Azeiteiro, U., Martinho, F., Pardal, M.A., 2007. Climate variability and planktonic communities: the effect of an extreme event (severe drought) in a southern European estuary. Estuarine Coastal & Shelf Sciences 73, 725–734. Davis, S.M., Childers, D.L., Lorenz, J.J., Wanless, H.R., Hopkins, T.E., 2005. A conceptual model of ecological interactions in the mangrove estuaries of the Florida Everglades. Wetlands 25 (4), 832–842. de Brye, B., de Brauwere, A., Gourgue, O., Delhez, E.J.M., Deleersnijder, E., 2013. Reprint of Water renewal timescales in the Scheldt Estuary. Journal of Marine Systems 128, 3–16. de Castro, M., Go´mez-Gesteira, M., Alvarez, I., Prego, R., 2004. Negative estuarine circulation in the Ria of Pontevedra (NW Spain). Estuarine Coastal & Shelf Sciences 60, 301–312. De Marco, S.G., Beltrame, M.O., Freije, R.H., Marcovecchio, J.E., 2005. Phytoplankton dynamic in Mar Chiquita coastal lagoon (Argentina), and its relationship with potential nutrient sources. Journal of Coastal Research 21 (4), 818–825. De Marco, S.D., Botte´, S.E., Marcovecchio, J.E., 2006. Mercury distribution in abiotic and biological compartments within several estuarine systems from Argentina: 1980–2005 period. Chemosphere 65 (2), 213–233. Du¨rr, H.H., Meybeck, M., Hartmann, J., Laruelle, G.G., Roubeix, V., 2011. Global spatial distribution of natural riverine silica inputs to the coastal zone. Biogeosciences 8 (3), 597–620. Eberlein, K., Kattner, G., 1987. Automatic method for the determination of ortho-phosphate and total dissolved phosphorus in the marine environment. Fresenius’ Zeitschrift fu¨r Analytische Chemie 326 (4), 354–357.

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Elliott, M., Whitfield, A.K., 2011. Challenging paradigms in estuarine ecology and management. Estuarine Coastal & Shelf Sciences 94, 306–314. Elsdon, T.S., De Bruin, M.B.N.A., Diepen, N.J., Gillanders, B.M., 2009. Extensive drought negates human influence on nutrients and water quality in estuaries. The Science of the Total Environment 407, 3033– 3043. Falco, S., Niencheski, L.F., Rodilla, M., Romero, I., Gonza´lez del Rı´o, J., Sierra, J.P., Mo¨sso, C., 2010. Nutrient flux and budget in the Ebro estuary. Estuarine Coastal & Shelf Sciences 87, 92–102. Fan, P.-P., Guo, D., 2010. Slow decomposition of lower order roots: a key mechanism of root carbon and nutrient retention in the soil. Oecologia 163 (2), 509–515. Fasano, J.L., Herna´ndez, M.A., Isla, F.I., Schnack, E.J., 1982. Aspectos evolutivos y ambientales de la laguna Mar Chiquita (provincia de Buenos Aires, Argentina). Oceanologica Acta NoSP 285–292. Faye, D., de Morais, L.T., Raffray, J., Sadio, O., Thiaw, O.T., Le Loc’h, F., 2011. Structure and seasonal variability of fish food webs in an estuarine tropical marine protected area (Senegal): evidence from stable isotope analysis. Estuarine Coastal & Shelf Sciences 92, 607–617. Feijoo´, C.J., Lombardo, R.J., 2007. Baseline water quality and macrophyte assemblages in Pampean streams: a regional approach. Water Research 41, 1399–1410. Feijoo´, C.J., Giorgi, A., Ferreiro, N., 2011. Phosphorus uptake in a macrophyte-rich pampean stream. Limnologica 41, 285–289. Freije, R.H., Asteasuain, R.O., Rusansky, C.N., Ferrer, L.D., Andrade, J.S., De Marco, S.G., Pozzobo´n, M.V., Marcovecchio, J.E., 1996. Spatial and temporal distribution of inorganic nutrients in Mar Chiquita coastal lagoon (Argentina). In: Marcovecchio, J.E. (Ed.), Pollution Processes in Coastal Environments. Univ. Nac. de Mar del Plata, Mar del Plata, Argentina, pp. 133–138. Garcı´a, N.O., Mechoso, C.R., 2005. Variability in the discharge of South American rivers and in climate. Hydrological Sciences Journal 50 (3), 459–478. Gentile, E.E., Gonza´lez, S.G., 2001. Social vulnerability to floods in Buenos Aires city (Argentina): the cases of La Boca neighbourhood and the basin of Maldonado stream. In: Open Meeting of Global Environmental Change Research Community (Rio de Janeiro, 6–8 October 2001), http://sedac.ciesin.org/openmeeting/downloads/ 1005790181_presentation_sgonzalez_egentile_riopaper.doc. Giletto, C.M., Echeverrı´a, H.E., 2013. Nitrogen balance for potato crops in the southeast pampas region, Argentina. Nutrient Cycling in Agroecosystems 95 (1), 73–86. Gillanders, B.M., Elsdon, T.S., Halliday, I.A., Jenkins, G.P., Robins, J.B., Valesini, F.J., 2011. Potential effects of climate change on Australian estuaries and fish utilising estuaries: a review. Marine & Freshwater Research 62, 1115–1131. Gime´nez, L., 2003. Potential effects of physiological plastic responses to salinity on population networks of the estuarine crab Chasmagnathus granulata. Helgoland Marine Research 56, 265–273. Grasshoff, K., Erhardt, M., Kremling, K., 1983. Methods in Seawater Analysis, 2nd ed. Verlag-Chemie, Weinheim, Germany, pp. 365. Grondona, S.I., Martı´nez, D.E., Benavente, M., Gonzalez, M., Massone, H.E., Miglioranza, K.S., 2013. Determinacio´n de para´metros hidra´ulicos en columnas experimentales de suelos del sudeste de la provincia de Buenos Aires. Revista de la Facultad de Ciencias Agrarias 45 (2), 115– 127. Hassan, G.S., Espinosa, M.A., Isla, F.I., 2011. Fluctuaciones de salinidad durante el Holoceno en la laguna costera de Mar Chiquita (Provincia de Buenos Aires): una aproximacio´n cuantitativa basada en diatomeas. Ameghiniana 48 (4), 496–507. Hessen, D.O., Carroll, J.L., Kjeldstad, B., Korosov, A.A., Pettersson, L.H., Pozdnyakov, D., Sørensen, K., 2010. Input of organic carbon as determinant of nutrient fluxes, light climate and productivity in the Ob and Yenisey estuaries. Estuarine, Coastal and Shelf Science 88, 53–62. Jeon, J., Kannan, K., Lim, B.J., Ane, K.G., Kim, S.D., 2011. Effects of salinity and organic matter on the partitioning of perfluoroalkyl acid (PFAs) to clay particles. Journal of Environmental Monitoring 13, 1803–1810. Johnson, L.T., Tank, J.L., Arango, C.P., 2009. The effect of land use on dissolved organic carbon and nitrogen uptake in streams. Freshwater Biology 54 (11), 2335–2350. Kasai, A., Kurikawa, Y., Ueno, M., Robert, D., Yamashita, Y., 2010. Saltwedge intrusion of seawater and its implication for phytoplankton dynamics in the Yura Estuary, Japan. Estuarine Coastal & Shelf Sciences 86, 408–414. Kayhanian, M., Fruchtman, B.D., Gulliver, J.S., Montanaro, C., Ranieri, E., Wuertz, S., 2012. Review of highway runoff characteristics: comparative analysis and universal implications. Water Research 46, 6609– 6624.

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ECOHYD-248; No. of Pages 15 14

J.E. Marcovecchio et al. / Ecohydrology & Hydrobiology xxx (2019) xxx–xxx

Kirkby, M.J., 2010. Distance, time and scale in soil erosion processes. Earth Surface Processes Landforms 35, 1621–1623. Knee, K.L., Paytan, A., 2011. Submarine Groundwater Discharge: a source of nutrients, metals, and pollutants to the Coastal Ocean. In: Wolanski, E., McLusky, D.S. (Eds.), Treatise on Estuarine and Coastal Science, vol. 4Academic Press, Elsevier Inc., Waltham, pp. 205–233 (Ch. 4.08, ISBN-9-780-08087-885-0). Latimer, J.S., Charpentier, M.A., 2010. Nitrogen inputs to seventy-four southern New England estuaries: application of a watershed nitrogen loading model. Estuarine Coastal & Shelf Sciences 89, 125–136. Lanfredi, N.W., Balestrini, C.F., Mazio, C.A., Schmidt, S.A., 1981. Tidal sandbanks in Mar Chiquita coastal lagoon, Argentina. Journal of Coastal Research 3 (4), 515–520. Liu, Q., Dai, M., Chen, W., Huh, C.-A., Wang, G., Li, Q., Charette, M.A., 2012. How significant is submarine groundwater discharge and its associated dissolved inorganic carbon in a river-dominated shelf system? Biogeosciences 9, 1777–1795. Liu, Y., Wang, Z., Guo, H.C., Yu, S.X., Sheng, H., 2013. Modelling the effect of weather conditions on Cyanobacterial Bloom Outbreaks in Lake Dianchi: a rough decision-adjusted logistic regression model. Environmental Modelling & Assessment 18, 199–207. Lorenzen, C.J., Jeffrey, S.W., 1980. Determination of chlorophyll in seawater. In: UNESCO Technical Papers on Marine Sciences 35. pp. 1–20. Marcovecchio, J.E., De Marco, S.G., Pozzobo´n, M.V., Gavio, M.A., Asteasuain, R.O., Rusansky, C.N., Ferrer, L.D., Andrade, J.S., Freije, R.H., 1997. The role of estuaries as buffer zones to litoral marine environments: the case of Mar Chiquita coastal lagoon, in Argentina. In: Martins Paiva, A., Weber, R. (Eds.), Proceedings of the VII Congresso Latinoamericano sobre Cieˆncias do Mar, vol. 2. Univ. de Sa˜o Paulo, Sa˜o Paulo (Brazil), pp. 128–130. Marcovecchio, J.E., Freije, R.H., De Marco, S.G., Gavio, M.A., Ferrer, L.D., Andrade, J.S., Beltrame, M.O., Asteasuain, R.O., 2006. Seasonality of hydrographic variables in a coastal lagoon: Mar Chiquita, Argentina. Aquatic Conservation: Marine & Freshwater Ecosystems 16 (4), 335– 347. Martı´nez, M.L., Intralawan, A., Va´zquez, G., Pe´rez-Maqueo, P., Sutton, P., Landgrave, R., 2007. The coast of our world: ecological, economic and social importance. Ecological Economics 63, 254–272. Menone, M.L., Bortolus, A., Botto, F., Aizpu´n de Moreno, J.E., Moreno, V.J., Iribarne, O., Metcalfe, T.L., Metcalfe, C.D., 2000. Organochlorine contaminants in a coastal lagoon in Argentina: analysis of sediment, crabs, and cordgrass from two different habitats. Estuaries 23 (4), 583–592. Menone, M.L., Aizpu´n de Moreno, J.E., Moreno, V.J., Lanfranchi, A.L., Metcalfe, T.L., Metcalfe, C.D., 2001. Organochlorine pesticides and PCBs in a Southern Atlantic coastal lagoon watershed, Argentina. Archives of Environmental Contamination & Toxicology 40, 355–362. Mercado, L.M., Go´mez, N., 1998. Fitoplancton del Rı´o Parana´ de las Palmas y efectos ocasionados por la central nuclear Atucha (Bs. As., Argentina). Aquatec 5, 21–33. Mongin, M., Matear, R., Chamberlain, M., 2011. Seasonal and spatial variability of remotely sensed chlorophyll and physical fields in the SAZ-Sense region. Deep-Sea Research II 58, 2082–2093. Moore, W.S., Shaw, T.J., 2008. Fluxes and behavior of radium isotopes, barium, and uranium in seven Southeastern US rivers and estuaries. Marine Chemistry 108, 236–254. Neveux, N., Magnusson, M.E., Maschmeyer, T., De Nys, R., Paul, N.A., 2015. Comparing the potential production and value of high-energy liquid fuels and protein from marine and freshwater macroalgae. GCB Bioenergy 7, 673–689. Olivier, S.R., Escofet, A., Penchaszadeh, P.E., Orensanz, J.M., 1972a. Estudios ecolo´gicos de la regio´n estuarial de Mar Chiquita (Buenos Aires, Argentina). I. Las comunidades bento´nicas. Anales de la Sociedad Cientı´fica Argentina 193 (5/6), 239–262. Olivier, S.R., Escofet, A., Penchaszadeh, P.E., Orensanz, J.M., 1972b. Estudios ecolo´gicos de la regio´n estuarial de Mar Chiquita (Buenos Aires, Argentina). II. Relaciones tro´ficas interespecı´ficas. Anales de la Sociedad Cientı´fica Argentina 193 (1/2), 89–105. Park, J.-H., Duan, L., Kim, B., Mitchell, M.J., Shibata, H., 2010. Potential effects of climate change and variability on watershed biogeochemical processes and water quality in Northeast Asia. Environment International 36, 212–225. Pawlowicz, R., Wright, D.G., Millero, F.J., 2010. The effects of biogeochemical processes on oceanic conductivity/salinity/density relationships and the characterization of real seawater. Ocean Science Discussions 7, 773–836. Perakis, S.S., Hedin, L.O., 2002. Nitrogen loss from unpolluted South American forests mainly via dissolved organic compounds. Nature 415, 416–420.

Pe´rez-Ruzafa, A., Marcos, C., Pe´rez-Ruzafa, I.M., Pe´rez-Marcos, M., 2011. Coastal lagoons: ‘‘transitional ecosystems’’ between transitional and coastal waters. Journal of Coastal Conservation 15, 369–392. Perillo, G.M.E., Piccolo, M.C., Marcovecchio, J.E., 2006. Coastal oceanography of the western south Atlantic continental shelf (338 to 558S). In: Robinson, A.R., Brink, K.H. (Eds.), The Sea. The Global Coastal Ocean: Interdisciplinary Regional Studies and Syntheses, vol. 14 – Part AHarvard University Press, Cambridge, Massachusetts, USA, pp. 295–327 (Ch. 9, ISBN-0-674-01527-4). Philippart, C.J.M., van Iperen, J.M., Cade´e, G.D., Zuur, A.F., 2010. Long-term field observations on seasonality in Chlorophyll-a concentrations in a shallow coastal marine ecosystem, the Wadden Sea. Estuaries & Coasts 33, 286–294. Piola, A.R., Falabella, V., 2009. El mar patago´nico. Atlas del Mar Patago´nico: especies y espacios. Buenos Aires, Wildlife Conservation Society y Birdlife International, pp. 54–75. Pizarro, H., Rodrı´guez, P., Bonaventura, S.M., O’Farrell, I., Izaguirre, I., 2007. The sudestadas: a hydro-meteorological phenomenon that affects river pollution (River Luja´n, South America). Hydrology Science Journal 52 (4), 702–712. Rothenberger, M.B., Burkholder, J.M., Brownie, C., 2009. Long-term effects of changing land use practices on surface water quality in a coastal river and lagoonal estuary. Environmental Management 44 (3), 505– 523. Seitzinger, S.P., Mayorga, E., Bouwman, A.F., Kroeze, C., Beusen, A.H.W., Billen, G., Van Drecht, G., Dumont, E., Fekete, B.M., Garnier, J., Harrison, J.A., 2010. Global river nutrient export: a scenario analysis of past and future trends. Global Biogeochemical Cycles 24, 1–16, GB0A08. Sharpley, A., Jarvie, H.P., Buda, A., May, L., Spears, B., Kleinman, P., 2013. Phosphorus legacy: overcoming the effects of past management practices to mitigate future water quality impairment. Journal of Environmental Quality 42 (5), 1308–1326. Shen, J., Yuan, L., Zhang, J., Li, H., Bai, Z., Chen, X., Zhang, W., Zhang, F., 2011. Phosphorus dynamics: from soil to plant. Plant Physiology 156, 997–1005. Smith, R.L., Smith, T.M., 2001. Ecologı´a. Addison Wesley, Pearson Educacio´n, Madrid, Spain. Sokal, R.R., Rohlf, F.J., 1981. Biometry, 2nd ed. W.H. Freeman & Co, New York (USA), pp. 668. Souchu, P., Bec, B., Smith, V.H., Laugier, T., Fiandrino, A., Benau, L., Orsoni, V., Collos, Y., Vaquer, A., 2010. Patterns in nutrient limitation and chlorophyll a along an anthropogenic eutrophication gradient in French Mediterranean coastal lagoons. Canadian Journal of Fisheries & Aquatic Sciences 67 (4), 743–753. Spivak, E.D., Gavio, M.A., Navarro, C.E., 1991. Life history and structure of the World’s Southernmost Uca population: Uca uruguayensis (Crustacea, Brachyura) in Mar Chiquita lagoon (Argentina). Bulletin of Marine Sciences 48 (3), 679–688. Staehr, P.A., Testa, J.M., Kemp, W.M., Cole, J.J., Sand-Jensen, K., Smith, S.V., 2012. The metabolism of aquatic ecosystems: history, applications, and future challenges. Aquatic Sciences 74, 15–29. Statham, P.J., 2012. Nutrients in estuaries – an overview and the potential impacts of climate change. The Science of the Total Environment 434, 213–227. Stoate, C., Ba´ldi, A., Beja, P., Boatman, N.D., Herzon, I., van Doorn, A., de Snoo, G.R., Rakosy, L., Ramwell, C., 2009. Ecological impacts of early 21st century agricultural change in Europe – a review. Journal of Environmental Management 91, 22–46. Stro¨mqvist, J., Arheimer, B., Dahne´, J., Donnelly, C., Lindstro¨m, G., 2012. Water and nutrient predictions in ungauged basins: set-up and evaluation of a model at the national scale. Hydrology Science Journal 57 (2), 229–247. Struyf, E., Smis, A., Van Damme, S., Garnier, J., Govers, G., Van Wesemael, B., Conley, D.J., Batelaan, O., Frot, E., Clymans, W., Vandevenne, F., Lancelot, C., Goos, P., Meire, P., 2010. Historical land use change has lowered terrestrial silica mobilization. Nature Communications 1 (129), 1–7. TECHNICON1, 1973. Silicates in water and seawaterIn: Industrial Method No.186-72W/B. . Treguer, P., Le Corre, P., 1975. Analyse des sels nutritifs sur Autoanalyzer II: Nitrates-nitrites. In: Manuel d’Analyse des Sels Nutritifs dans l’Eau de MerUniversite‘du Bretagne Occidentale, , pp. 11–22. Tremblay, L., Kohl, S.D., Rice, J.A., Gagne, J.-P., 2005. Effects of temperature, salinity, and dissolved humic substances on the sorption of polycyclic aromatic hydrocarbons to estuarine particles. Marine Chemistry 96, 21–34. Violaki, K., Zarbas, P., Mihalopoulos, N., 2010. Long-term measurements of dissolved organic nitrogen (DON) in atmospheric deposition in the Eastern Mediterranean: fluxes, origin and biogeochemical implications. Marine Chemistry 120, 179–186.

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005

G Model

ECOHYD-248; No. of Pages 15 J.E. Marcovecchio et al. / Ecohydrology & Hydrobiology xxx (2019) xxx–xxx Weston, N.B., Vile, M.A., Neubauer, S.C., Velinsky, D.J., 2011. Accelerated microbial organic matter mineralization following salt-water intrusion into tidal freshwater marsh soils. Biogeochemistry 102, 135–151. Wetz, M.S., Hutchinson, E.A., Lunetta, R.S., Paerl, H.W., Taylor, J.C., 2011. Severe droughts reduce estuarine primary productivity with cascading effects on higher trophic levels. Limnology & Oceanography 56 (2), 627–638. Wetz, M.S., Yoskowitz, D.W., 2013. An ‘‘extreme’’ future for estuaries? Effects of extreme climatic events on estuarine water quality and ecology. Marine Pollution Bulletin 69, 7–18.

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Whitehead, P.G., Wilby, R.L., Battarbee, R.W., Kernan, M., Wade, A.J., 2009. A review of the potential impacts of climate change on surface water quality. Hydrology Science Journal 54 (1), 101–123. Wu, E.M.-Y., Kuo, S.-L., 2012. Applying a multivariate statistical analysis model to evaluate the water quality of a watershed. Water Environment Research 84 (12), 2075–2085. Yin, K., 2002. Monsoonal influence on seasonal variations in nutrients and phytoplankton biomass in coastal waters of Hong Kong in the vicinity of the Pearl river estuary. Marine Ecology-Progress Series 245, 111– 122.

Please cite this article in press as: Marcovecchio, J.E., et al., Hydraulic stopper effect as a regulator of inorganic nutrients distribution in Mar Chiquita coastal lagoon (Argentina). Ecohydrol. Hydrobiol. (2019), https://doi.org/10.1016/ j.ecohyd.2019.04.005