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

COUSSEAU M.B., GARCÍA DE LA ROSA S.B., FIGUEROA D. E., DÍAZ DE ASTARLOA J.M., GONZÁLEZ CASTRO M., MABRAGAÑA E., BARBINI S., RETA R., MARTOS P.

Tallin, Estonia.

Congreso; XI European Congerss of Ichthyology; 2004

Estonian Marine Institute, University of Tartu

 Coastal lagoons serve to fishes as refuge, power supply and nursery areas during critical stages of their developments. These enviroments are influencied by temperature and salinity variations, affecting the fish species inhabiting the area. In South America, Mar Chiquita is the southermost lagoon with a long and semiplugged channel, where fresh water fishes and marine fish inhabit. 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 continuos monitoring, in order to know how salinity and temperature varied, and how these parameters influenced the fish specific composition and their distribution. Sampling was carried out in two different areas with a 25 m length and 2 m height net, with cod.end mesh of 120 mm and 64 mm width. All fish specimens were mesured and weighed, and temperature and salinity were simultaneosly recorded. The temperature showed cyclical changes during the year, that repetead during the five years considered, with no diferences between sampling areas. Temperature varied from 18.47 to 21.30 ºC in the warm season registered the highest fish capture. For 120 mm net a bimodal Ls fish distribution (modes 290 and 410 mm) was found. Abundant species, in decresing order, were menhaden (Brevoortia aurea), mullet (Mugil platanus), black drum (Pogonias cromis) and sole (Paralichthys orbignyanus). For 64 mm net a unimodal Ls distribution (mode 220 mm) was recorded. The more abundant fishes were the same than the ones in the 120 mm net, though four different species (Odontesthes 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.