Mar Chiquita Coastal Lagoon (Buenos Aires, Argentina): physical and ichthyological results from a five years (1999-2003) continuos monitoring.

COUSSEAU, MARÍA B.; GARCÍA DE LA ROSA, SUSANA B.; FIGUEROA, DANIEL E.; DIAZ DE ASTARLOA, JUAN. M.; GONZÁLES CASTRO, MARIANO; MABRAGAÑA, EZEQUIEL; BARBINI, SANTIAGO A.; RETA, RAÚL; MARTOS, PATRICIA

Tallinn, Estonia

Congreso; XI European Congress of Ichthyology; 2004

Estonian Marine Institute, University of Tartu

Coastal lagoons serve to fishes as refuge, power suplí and nuersery areas Turing critical of their developments. These enviroments are influenced by temperature and salinity variations, affecting the fish species inhabiting the area. In South America, Mar Chiquita is the southernmost lagoon with a long and semiplugged channel, where fresh water fishes and marine fishes inhabits. In 1996 it was declared as “World Reservation of the Biosphere” by UNESCO. The present work summarises the physical and ichthyological results during a five years period (1999-2003) of continuous monitoring, in order to know how salinity and temperature varied, and how these parameters influenced the fishes specific composition and their distribution. Sampling was carried out in two different areas with a 25 m lenght and 2 m height net, with cod-end mesh of 120 mm and of 64 mm width. All fish specimens were measures and weighted, and temperature and salinity were simultaneously recorded. The temperature showed cyclical changes during the year, that repeated during the five years considered, with no differences between sampling areas. Temperature varied from 18.47 to 21.30ºC in the warm season, with maximums in December and January, whereas its minimum was registered in July. Salinity proved to be extremely variable (0.91-33.49 ups), depending on the tides, the direction and wind force and contribution of fresh water. A total of 16 fish species were captured. The warm season registered the highest fish capture. For 120 mm net a bomodal Ls fish distribution (modes 290 and 410 mm) was found. Abundant species, in decreasing order, were menhaden (Brevoortia aurea), mullet (Mugil platanus), black drum (Pogonias cromis) and sole (Paralichrhys orbignyanus). For 64 mm net a unimodal Ls distribution (mode 220 mm( was recorded. The more adundant fishes were the same than the ones in the 120 mm net, though four different species (Odonthestes argentinensis, O. platensis, Lycengraulis olidus and Mugil curema) never captured with 120 mm net were found. M. curema constitutes the first record for Argentinean water of this species.