Contribution
Environmental stress on Corbicula fluminea (Bivalvia) in the Paraná River delta (Argentina): complex pollution-related disruption of population structures
Boltovskoy, Demetrio; Correa, Nancy; Cataldo, Daniel; Stripeikis, Jorge; Tudino, Mabel
Archiv für Hydrobiologie Volume 138 Number 4 (1997), p. 483 - 507
53 références bibliographiques
publié: Mar 14, 1997
DOI: 10.1127/archiv-hydrobiol/138/1997/483
ArtNo. ESP141013804003, Prix: 29.00 €
Abstract
Corbicula fluminea was collected at monthly intervals in November 1991-June 1993, and in March, April 1995 at a site located in the vicinity of strong sources of industrial and sewage effluents (confluence of the Rivers San Antonio and Vinculación, SaV); and in November 1994 and March, April 1995 at a presumably less polluted one (Paraná de las Palmas River, PP), in the lower delta of the Paraná River (Argentina). Abundances at SaV ranged between 430 and 10,300 ind. m-2, being noticeably higher than those at PP, as well as those at 19 stations between and around these two locales. Shell lengths at SaV were monotonous throughout the 19-months period, over 90 % of the clams varying between 16 and 22.5 mm in length; no discernible cohorts were recorded. At PP, on the other hand, juveniles below 5 mm were largely dominant, and shells above 25-30 mm in length were very common. Larvae retrieved from the gills of gravid clams showed much greater mortality rates in waters from SaV (up to 75 % after 120 hr), than in those from PP and in the control (approximately 10 % after 192 hr). The first internal growth-related mark in clams from SaV was closer to the umbo (mean: 14.2 mm), than that in clams from PP (mean: 24 mm). It is concluded that inadequate water quality at SaV is responsible for 100 % mortalities of newborns, for dwarfed adult clams, and for the lack of discernible cohorts. High densities at this site are presumably maintained by downstream dispersal of small adults.
Mots-clefs
sewage • larvae • mortality • adults • clams • Paraná River • Argentina