Andrea Cecilia Hued

Development and validation of a Biotic Index for evaluation of environmental quality in the central region of Argentina

The Suquía River (Córdoba, Argentina) has become an important issue because it flows into Mar Chiquita Lake, one of the largest saline lakes in the world. This water body, together with the expansive swamps of the Dulce River on the northern shore and the mouth of Suquía and Xanaes River, is considered one of the most important wetlands in Argentina in terms of biodiversity in a range of freshwater to very saline environments. Nevertheless, the presence of densely populated urban settlements and the increasing environmental impact due to anthropogenic activities characterize the central and lower sections of Suquía River Basin. Fishes are particularly affected and change their distribution and abundance as a consequence of the environmental deterioration. We collected information on fish fauna to develop and validate a Biotic Index to assess degradation of the Suquía River Basin. We classified fish species according to their sensitiveness or tolerance to environmental degradation, based on their distribution and abundance variations along a water quality gradient in order to design a Biotic Index for Suquía River Basin. The set of metrics used in the Biotic Index calculation was conformed by: the abundance of Astyanax eigenmanniorum, Rineloricaria catamarcensis, Gambusia affinis and Cnesterodon decemmacultus, the proportion of sensitive species richness, and the proportion of tolerant species richness. They clearly distinguished between the impaired and referenced sites. We demonstrated that it is possible to use fish as indicators of water quality in Córdoba Province (central part of Argentina) in order to carry out rapid and relatively inexpensive monitoring and conservation programs. The application of this Biotic Index showed that fish assemblages reflect the watershed conditions and are sensitive to changes in water quality across the environmental gradient.

Haematological parameters in a neotropical fish, Corydoras paleatus (Jenyns, 1842) (Pisces, Callichthyidae), captured from pristine and polluted water

We report normal ranges of haematological indices in healthy Corydoras paleatus from an unpolluted area. Haematological parameters studied include: erythrocyte counts (Er), haematocrit (Ht), haemoglobin concentration (Hb), mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC). Normal red blood parameters did not change according to maturation stages, sex or seasons. Then, we compared them with those coming from fish captured in a site polluted by sewage. Fish exposed to pollution presented significantly higher values of Er, Ht, Hb, MCH and MCHC than those captured in an unpolluted area. Discriminant analysis showed that Hb is a key parameter to point out differences between populations exposed to different environmental conditions. We suggest that haematological values of C. paleatus, registered during this study, could be used as biomarkers in future works evaluating the incidence of environmental stress on fish as well as pointing out changes in the water quality.

Integral assessment of pollution in the Suquía River (Córdoba, Argentina) as a contribution to lotic ecosystem restoration programs.

The Suquía River lower-middle basin (Córdoba, Argentina) is subject to a strong anthropic impact because it receives pollutants from different sources (industries, wastewaters, heavy traffic, agricultural land use, etc.) We have assessed the degree of watershed degradation of Suquía River lower-middle sections through the analysis of different ecosystem compartments (air, water, riparian soil, sediments and biota), in order to provide useful data to be considered in future river restoration programs. Four study sites were selected along the river (La Calera city, Córdoba city, Corazón de María village and Río Primero city) which were sampled during the low- and high-water flow periods. We analyzed: a) chemical and physical characteristics of water, sediments, and riparian soil; b) heavy metal content of water and sediments, and c) semi-volatile organic compounds in air. Besides, pollutant bioindicators such as fish assemblages, lichens (Usnea amblyoclada), vascular plants (Tradescantia pallida), and microorganisms (fecal coliform and Escherichia coli) were used to further assess the status of the river. All analyzed ecological compartments were affected by water pollution, particularly, fish assemblages, sediments and riparian soils by heavy metal and coliform bacteria. Moreover, we detected a possible contribution of sulfur and a high pollutant content in air that merit further research about other air-water exchanges. Accordingly, we strongly suggest that an action to restore or remediate the anthropic effect on the Suquía River be extended to all possible compartments along the river.

Bioindicators and Biomarkers of Environmental Pollution in the Middle-Lower Basin of the Suquía River (Córdoba, Argentina)

The Suquía River middle-lower basin (Córdoba, Argentina) is subject to a strong anthropogenic impact because it receives pollutants from different sources. Recent studies have shown the importance and the need of approaching the monitoring process of water quality from integral perspectives through the use of chemical as well as biological methods. The main goal of this study was to evaluate the fish species Jenynsia multidentata as a bioindicator of environmental pollution in the middle-lower basin of the Suquía River using biotransformation and antioxidant enzymes as well as gill and liver histopathology as biomarkers. We also studied the fish-assemblage characteristics through the fish species pattern variation and the application of a biotic index based on fish data. Our study also included the analysis of a water-quality index, heavy-metal concentrations in sediment and water, and pesticide concentrations in sediment. The chemical analyses of the middle-lower Suquía River basin showed a water-quality degradation gradient. Fish-assemblage structure changed with increasing water pollution, showing a simpler structure at the most polluted area. According to the bioitc index, the variation pattern of fish assemblages reflected the aquatic environmental deterioration. Both molecular and histopathological biomarkers reflected the same trend in relation to water quality. However, enzymes varied with more acute precision between seasons. In addition, each enzyme presented with different sensibility. At tissue level, the histopathological analysis detected chronic contamination at both stations and seasons. The present work, which comprises different levels of biological organization together with chemical analyses, generated particular although complementary information, thus evidencing the same trend of aquatic contamination. Thus, the development of integral investigations gives a comprehensive approach and becomes the most effective tool to construct policies both preventive and palliative. Our study constitutes a good model to be applied in other endorheic basins of South America.

Effects of the synthetic estrogen 17α-ethinylestradiol on aromatase expression, reproductive behavior and sperm quality in the fish Jenynsia multidentata.

Abstract The synthetic estrogen 17α-ethynylestradiol (EE2) has been increasingly detected in sewage effluents in the last two decades. The aim of the present study was determined if EE2 exposure adversely affected reproduction in internally fertilizing fish species Jenynsia multidentata. Sexual behavior, brain and gonadal aromatase expression as well as sperm quality were evaluated. The brain aromatase expression, reproductive behavior, spermatozoa viability and gonadosomatic index were sensitive biomarkers of EE2 effects on this species. The condition factor, hepatosomatic index, gonadal aromatase expression, sperm count and sperm velocities were unaltered after EE2 exposure. The present work highlights the importance of using a combination of several biomarkers to study the effects of estrogenic compounds, especially when trying to link these results to potential population-level effects.

Reproductive Impairment of a Viviparous Fish Species Inhabiting a Freshwater System with Anthropogenic Impact

The potential threat to animal reproduction by contaminated freshwater systems posed the necessity to identify and develop bioindicators and biomarkers to be used for screening and evaluation of the effects in organisms. The main goal of this work was to determine, through histological analyses and changes in gonopodium morphology, whether a freshwater system polluted by anthropogenic activities—sewage, agricultural, and industrial—could cause alterations at the organ level. We also propose the live-bearing fish, Jenynsia multidentata, as a species suitable to study the effects of contaminated aquatic environments. We compared male fish sampled at two different stations in Suquía River basin (Córdoba, Argentina), both differing in degree of pollution, through liver and testis histology and gonopodial morphometric parameters. The water quality, based on the physicochemical characteristics of the studied stations, varied markedly with a decrease in water quality at the downstream site (station 2). At the highest polluted area, detrimental effects on liver and testis were evidenced on histological analysis. Male individuals from station 2 also presented noticeable structural changes of the anal fin, such as a straight gonopodium and abnormal tip area. The present results demonstrate that a freshwater system polluted by the impacts of anthropogenic activities has detrimental effects to J. multidentata. The alterations registered in individuals from the polluted station indicate an impairment of male reproductive performance and imply a risk for other live-bearing species as well as the entire biodiversity. We consider J. multidentata a sentinel species that is useful to evaluate the potential risk present in the studied basin not only to itself but to other species as well.

Abundance and distribution of fish fauna in Suquía river basin (Córdoba, Argentina)

In this work a characterization of the Suquia river basin is presented. Fish were collected from sixteen selected sites from 1998 to 2002 in the main rivers of the basin: San Francisco brook, Cosquin river, Yuspe river, San Antonio river and Suquia river. Relative abundance, species richness, diversity and dominance were estimated. It was applied a Discriminant Analyses in order to determine differences in species composition among the studied rivers, and before and after the main urban settlement. Twenty one fish species were collected along the basin. They belong to twelve families and six orders. Fish species showed different patterns of variation. The Discriminant Analysis indicated important fish fauna differences between rivers. Although they share almost all the fish species, they showed different patterns of abundance between sites. The results also demonstrated the negative impact of Cordoba city on fish assemblages. This work provides new data about the present state of fish fauna of Suquia river Basin and constitutes a starting point that will allow the application of monitoring and evaluation programs in order to know the quality of the aquatic resources.

Effects of water quality variations on fish communities in the central part of Argentina, South America

Variations in the physical, chemical and biological characteristics of lotic systems often produce changes in the distribution and strucrure of fish communities (UNESCO 1992). These changes, either spatial or temporal, provide useful information on the quality and biological imegrity o f water resources (MARET et al. 1997). Human activities can permanently alter fish community structure. Numerous studies have shown that both fish species richness and diversity decrease in pol!uted systems (HILDREW & TOWNSEND 1987, CRUNKIL TON & DucHROW 1991). The basis for using biological monitoring of fish to assess environmental degradation lies in that the relative health of a fish community is a sensitive indicator of direct and indirect effects of stress on the entire aquatic ecosystem, thus indicating the ecological significance o f the perturbation (FAUSCH et al. 1990). In recent years, North American and European ichthyologists have attempted to relare physicochemical characteristics to fish distribution in order to establish the fish community attributes along a polluted or unpolluted river (FAUSCH et al. 1990, ÜBERDORff & HuGHES 1992, MARET et al. 1997, ZAMPELLA & BuNNELL 1998). Although many experimental studies have explored the response of fish to environmental factors, fish behaviour in relation to complex interactions between diverse variables in nature is difficult to describe. In Argentina, few studies attempted to relate the changes in fish assemblage composition to the variations of water quality in the field (MENNI et al. 1996, BISTONI et al. 1999). The Suquía Basin (in Córdoba Province, central Argentina, South America}, which flows into a hypersaline lake (Mar Chiquita Lake}, is a very complex system with increasing environmental impact. The system has almost pristine headwaters, but urban settlements are densely populated and there is increased use by tourists in the central and lower portions o f the system, resulting in a complex watershed. The main objective of the present study was to evaluate the effects of the physico-chemical water properties on the diversity and composition of fish communities, based on the fish species present.

Abundancia y distribución de las especies ícticas (Osteichthyes) del río San Francisco-Cosquín, Córdoba, Argentina

It was made the characterization of the San Francisco-Cosquin Mountain River fish community, Cordoba, Argentina. Samples of fish were taken from selected sites from November 1998 to November 1999. Eleven species were recorded, eight of which are first reports for this river. Relative abundance for each species, species richness, diversity and dominance were estimated. Bryconamericus iheringi (Boulenger, 1887) y Jenynsia multidentata (Jenyns, 1842) were the most abundant.

Effects of water quality on aspects of reproductive biology of Cnesterodon decemmaculatus

The Suquía River basin (Córdoba, Argentina) is under a strong negative impact due to multiple sources of anthropic pollution. The main goal of our study was to evaluate if variations in the water quality of Suquía river basin affect the reproductive biology of Cnesterodon decemmaculatus and determine if the responses provided by the species can be considered as biomarkers of river quality. This assessment was performed through the measurement of morphological, histological and somatic parameters in adult males collected at four sampling sites during the beginning and the end of the breeding season. The water quality evaluation carried out through the estimation of a water quality index (WQI) and pesticides concentrations in water, revealed a pollution gradient along the studied basin. The same variation pattern was registered for the somatic index. In addition, the analysis of the morphology of the male copulatory organ (gonopodium) showed that individuals collected at Córdoba city had the lowest Gonopodium-Somatic Index (Gonop-SI) value, while those sampled at the most polluted site showed abnormalities in the small structures of the gonopodium. On the other hand, few histological alterations were found in the liver whereas no alterations were found in gonads along the river. The results obtained allowed us to characterize the environmental conditions of the studied basin and demonstrated the water quality deterioration along the Suquía River.