Assessment of chitin variation in seston of a temperate estuary (Bahía Blanca, Argentina)

Abstract

Chitin was quantified in seston samples to determine its seasonal and spatial distribution in the estuary of Bahia Blanca. Sampling was conducted at three sites: Puerto Cuatreros, Maldonado, and Canal Vieja in autumn, winter, spring, and summer (2012–2013). Chitin concentrations were 3.79 ± 0.75 and 0.61 ± 0.36 chitin mg L −1 in autumn and winter, respectively. The proportion of chitin in the suspended particular matter (SPM) reached a maximum of 4% in autumn. There were statistical differences in chitin between seasons but not between sampling points. The particulate organic carbon (POC) ranged from 337.25 ± 30.52 µM in winter to 54.93 ± 26.10 µM in summer. The SPM varied from a maximum of 1172.17 ± 17.53 mg L −1 in spring to a minimum 71.42 ± 5.59 mg L −1 in autumn. In both cases, statistical differences were found between seasons but not between sampling points. The results indicated that the concentration of chitin as well as SPM and POC had a strong seasonal trend. The principal component analysis and the canonical analysis on the principal coordinates of environmental variables also highlighted the seasonal variation. The micro-detritus and planktonic organisms (fungi, diatoms, and copepods) in SPM and POC represent a chitinaceous substrate with a great importance for the study of the incorporation of compounds of nitrogen and carbon to the Bahía Blanca system.