Silverside Odontesthes Bonariensis Research Articles

The orobranchial structures in four neotropical silversides (Teleostei: Atherinopsidae) related with feeding habits

The morphology of the orobranchial structures in fish generally reflects the feeding habits and food preferences of a species and is key in understanding the process and habits of fish feeding. This work describes the orobranchial structures of four neotropical silversides (Teleostei: Atherinopsidae): the Mexican pike silverside Chirostoma estor, the Mexican blacknose silverside Chirostoma promelas, the Argentinian silverside Odontesthes bonariensis and Patagonian pejerrey Odontesthes hatcheri, and correlates their morphological features with existing information on gut contents and feeding habits in adult fish. Results of the compared and analysed data in the present study portray an integrative view of the specialised habits of the different species. Significant morphological differences, which are related to primary feeding habits of four species, were found. C. promelas shows to be more piscivorous compared to O. hatcheri, which has main benthic habits, while O. bonariensis and C. estor have more zooplanktivorous preferences. This information provides knowledge of feeding habits and ecological interactions of these species and their prey.

First molecular data for Lernaea cyprinacea (Copepoda: Cyclopoida) infesting Odontesthes bonariensis, a commercially important freshwater fish in Argentina.

Parasitic copepods of the family Lernaeidae are often found infesting freshwater fishes worldwide. They cause lernaeosis, a disease that can lead to serious pathogenic effects on their fish hosts. The most common lernaeid is the Lernaea cyprinacea, which has been widely introduced through importation of tropical fishes, e.g. cyprinids. In South America, it is one of the most common parasites both in wild and in farmed fish in the central region of Argentina. The silverside Odontesthes bonariensis is the most important fish of the sport fisheries of Argentina and one of the fish most affected by lernaeosis. Six specimens of copepods were collected from 30 specimens of O. bonariensis collected in a Pampean shallow lake (33°25'28"S 62°53'56"W) of Córdoba (Argentina). The 28S rRNA gene of L. cyprinacea was amplified by means of PCR to obtain the 28S rDNA sequence. The sequence obtained of this parasite from Argentina showed high genetic similarity with those from various geographical origins. The present study provided molecular characterization of L. cyprinacea in South America for the first time.

Genetic population structure and evidence of genetic homogeneity in populations of the Argentinian silverside Odontesthes bonariensis (Teleostei: Atherinopsidae) inhabiting central and northwestern Argentina

UBACYT X504 CC05 Basal Grant PFB 023 Millennium Nucleus NC120030 FONDECYT de Iniciacion 11150213 ICM P05-002

Otolith Sr:Ca ratio and morphometry as indicators of habitat of a euryhaline species: The case of the silverside Odontesthes bonariensis

The silverside Odontesthes bonariensis is a euryhaline species native of South America and represents a very important fishing resource for the Plata Basin (Argentina and Uruguay). This study compares the Sr:Ca ratio of water as well as the Sr:Ca ratio and morphometry of the sagittal otolith of the silverside present in different environments (one salt lake, two freshwater dams, one lagoon, and one estuary) in order to evaluate the use of these variables as markers of habitat. The pattern of the Sr:Ca ratio in the water agrees with the one found in the otoliths, showing a positive relationship with the conductivity of the water. Univariate and multivariate analyses of variance indicated significant differences (P < 0.05) among the localities studied for the morphometric indices. The discriminant function analysis provided a high percentage of correctly classified individuals for the saltwater environment (100%) and the lentic water bodies and estuary (60–80%), circularity and form factor being the most relevant morphometric variables. These results indicate that the Sr:Ca ratio and otolith morphometry are good markers of habitat for this important resource.

Trophic interactions between native and introduced fish species in a littoral fish community.

The trophic interactions between 15 native and two introduced fish species, silverside Odontesthes bonariensis and rainbow trout Oncorhynchus mykiss, collected in a major fishery area at Lake Titicaca were explored by integrating traditional ecological knowledge and stable-isotope analyses (SIA). SIA suggested the existence of six trophic groups in this fish community based on δ(13)C and δ(15)N signatures. This was supported by ecological evidence illustrating marked spatial segregation between groups, but a similar trophic level for most of the native groups. Based on Bayesian ellipse analyses, niche overlap appeared to occur between small O. bonariensis (<90 mm) and benthopelagic native species (31.6%), and between the native pelagic killifish Orestias ispi and large O. bonariensis (39%) or O. mykiss (19.7%). In addition, Bayesian mixing models suggested that O. ispi and epipelagic species are likely to be the main prey items for the two introduced fish species. This study reveals a trophic link between native and introduced fish species, and demonstrates the utility of combining both SIA and traditional ecological knowledge to understand trophic relationships between fish species with similar feeding habits.

Combined use of otolith microchemistry and morphometry as indicators of the habitat of the silverside (Odontesthes bonariensis) in a freshwater–estuarine environment

The silverside Odontesthes bonariensis is a highly salt-tolerant freshwater–estuarine species found in the Southern Hemisphere. The objective of the present study was to perform a simultaneous evaluation of the morphometry and microchemistry (Sr/Ca and Ba/Ca ratios) of the otoliths of this species to provide information on its displacements and to identify fish stocks. The morphometry and microchemistry of fish otoliths from three regions of the lower section of the Plata Basin (Uruguay River, Paraná River Delta and De la Plata River estuary) were compared. The results showed that otoliths of fish from the southern lower section of the Plata Basin tended to be circular in shape and had a lower ratio of sulcus perimeter to total otolith perimeter than those fish collected in the north of the studied region. There is a trend to increase the otolith Sr/Ca ratio with increasing water conductivity along a latitudinal (north–south) gradient, while the Ba/Ca ratio decreased significantly along such gradient. Present results suggest that the silverside population may be geographically divided along the north–south axis of the lower section of the Plata Basin.

Glycoproteins histochemistry of the gills of Odontesthes bonariensis (Teleostei, Atherinopsidae)

The histochemistry of glycoproteins (GP) in the mucous cells of the gills of the silverside Odontesthes bonariensis was identified with: (1) oxidizable vicinal diols; (2) sialic acid and some of their chain variants, carbon 7 ((7) C), carbon 8 ((8) C) or carbon 9 ((9) C); (3) sialic acid residues without O-acyl substitution and with O-acyl substitution at (7) C, (8) C or (9) C; (4) carboxyl groups and (5) sulphate groups. A battery of seven biotinylated lectins allowed GPs sugar residues to be distinguished. Mucous cells showed the presence of neutral, sulphated and sialylated GPs. Dolichos biflorus agglutinin (DBA) and Glycine max agglutinin (SBA) showed strong positive staining; Arachis hypogaea agglutinin (PNA), Ricinus communis agglutinin-I (RCA-I) and Triticum vulgaris agglutinin (WGA) showed moderate staining, while Ulex europaeus agglutinin-I (UEA-I) was completely negative.

Acute toxicity of three antifungal chemicals on silverside Odontesthes bonariensis (Valenciennes 1835) eggs

Fil: Pacheco Marino, Suani Giovanna. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico CONICET- La Plata. Instituto de Genetica Veterinaria Ing. Fernando Noel Dulout. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genetica Veterinaria; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Botanica Spegazzini; Argentina

Composition and diversity of ichthyofauna in La Viña reservoir (Córdoba, Argentina)

Several dams have been built in central and north Argentina. There are more than 20 reservoirs in Córdoba province, with a total estimated surface area of around 15,000 ha. Although construction of dams continues, some aspects about the richness, abundance and diversity of ichthyofauna in many of these environments are unknown, which prevents adequate management of fish resources. The goal of this work was to evaluate specific richness and diversity of ichthyofauna in La Viña reservoir (31 degrees 47' S and 65 degrees 01' W, 1,050 ha, 846 m asl), one of the major reservoirs in Córdoba. Fifteen seasonal samplings were made in 1999-2002 using trawl nets and gillnets. A total of 3,242 specimens belonging to 7 species distributed in 5 orders and 5 families were caught. The tetra Astyanax eigenmanniorum (52.9%) and the silverside Odontesthes bonariensis (29.3%) were the most abundant species; the latter is the main target species for lake fishing and had greatest biomass (63.8%). Average diversity for all samples was H'T = 1.63 (95% confidence interval 1.49 to 1.77). Shannon-Wiener and Simpson diversity indexes values were generally intermediate. Specific richness of La Viña reservoir was moderate compared with other impoundments in central and north Argentina.

Interactive effects of abiotic, hydrological and anthropogenic factors on fish abundance and distribution in natural run‐of‐the‐river shallow lakes

AbstractEcological processes in lowland rivers are mostly dominated by hydrology and its interactions with other environmental factors. Fish–habitat relationships in rivers are also influenced by human impacts.In this study, we describe patterns of abundance and distribution of fish species in a group of natural lowland river lakes along spatial anthropogenic and abiotic gradients when four hydrologically different summers are compared. We also describe the proportion of the total variances in fish species abundances that can be accounted for by selected abiotic (water conductivity), hydrological (water residence time) and human activity‐derived (total phosphorus (TP) concentration and NO3:NH4) variables. Consequently, our main purpose is to explore how abiotic and anthropogenic factors interact to affect fish abundance and distribution together with consistent results across different hydrological conditions. We conclude with a briefly discussion of some management implications.The anthropogenic impacts on water quality, the extreme hydrological variability and the fluctuating abiotic environment affected fish abundance and distribution. Pampa inland silverside Odontesthes bonariensis was benefited from a less human disturbed environment with higher water residence time and total salinity, whereas species as Cyphocharax voga, Parapimelodus valenciennis and Cyprinus carpio found these conditions largely disadvantageous. On the other hand, while most species showed stronger—either negative or positive—response to anthropogenic, hydrological or abiotic factors Oligosarcus jenynsii was only slightly affected.This paper identified the ecological function of a lowland river under its natural flow regime. There are not many opportunities to study unmodified rivers worldwide. Therefore, our findings may help in assessment programmes of fish communities in flow altered and human disturbed aquatic ecosystems. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Freshwater fishes of the Altiplano

Fisheries of the Altiplano, dating from 1500 to 2000 BC, are active in the Andean inter-montane plateau that extends from Ancash, Perú, to Antofagasta, Chile, at altitudes above 3600 m. The ancient and remote nature of these systems has merited the inclusion of many areas as National Parks and RAMSAR sites. Among 58 native fish species, 45 belong to the killifish complex Orestias and the rest to the catfish complex Trichomycterus. The main fishery resources consist of “ispi”, Orestias ispi, with 32 175 (64.5%) metric tons and “karachi”, Orestias of the group agassii, with 455 metric tons (0.9%). The introduced fishes “silversides”, Odontesthes bonariensis, and “trouts”, Oncorhynchus mykiss, contribute 16 900 metric tons (33.9%) and 324 metric tons (0.7%) respectively. Hydro-acoustic evaluations show a permanent diminution of the endemic Orestias. Lake species such as O. pentlandii “boga” and O. cuvieri “humanto” were important for their biogeographic relationships and were highly endemic. Native fishes are nowadays threatened by the salmonids, Oncorhynchus mykiss, Salvelinus namaycush, Salvelinus fontinalis and Salmo trutta, introduced since 1939. Later, the silverside Odontesthes bonariensis was introduced during 1955–1956.