Abnormal forms in Pinnularia gibba (Bacillariophyceae) in a polluted lowland stream from Argentina.

GÓMEZ, N.; LICURSI, M.

NOVA HEDWIGIA, ZEITSCHRIFT FUR KRYPTOGAMENKUNDE

Lugar: Alemania; Año: 2003 vol. 77 p. 389 - 398

0029-5035

The study of samples collected in Don Carlos Stream, a small stream that runs across an urbanised and industrialised area of the Pampean plain, displayed abnormalities in the valves of Pinnularia gibba Ehrenberg. Three sampling stations were positioned in different sectors of the stream: Station A is located upstream and exposed to agricultural activity, station B and station C are exposed to sewage effluent and to outflows from textile and metallurgical factories respectively. Acetate sheets placed on bricks, fastened with some staples, were used as artificial substrates and were exposed to colonisation during 21 days prior to collection. Diatoms from artificial substrates were sampled during three week. Several environmental variables were analysed: pH, conductivity, dissolved oxygen, biological oxygen demand, chemical oxygen demand, hardness, total suspended solids and nutrients. Also heavy metals (Cu, Cr, Cd, Zn) were examined in water and sediment. Two types of abnormalities were found: type I had valves exhibiting abnormal patterns of striations and/or deformed or interrupted raphe and type II included deformities in the outline of the valves, sometimes linked to anomalies in the striae or raphe. Multiple correlation showed a close relationship between the appearance of deformations and changes in water quality in Don Carlos Stream.