Freeze core sampling of the hyporheos: implications of use of electropositioning and different settling periods
Olsen, Dean A.; Matthaei, Christoph D.; Townsend, Colin R.
Archiv für Hydrobiologie Volume 154 Number 2 (2002), p. 261 - 274
published: May 29, 2002
ArtNo. ESP141015402004, Price: 29.00 €
Invertebrate densities and taxon richness in freeze cores were compared between three different settling periods (zero, two and seven days) as well as between samples taken with two variations of electropositioning and samples taken without electropositioning with a settling period. Species composition differed significantly among the three settling periods, but few significant differences were found in density or richness. Eriopterini were more abundant in hyporheic sediments (10-50 cm below sediment surface) in samples settled for two days than in those settled for seven days. Benthic densities (0-10 cm) of nematodes were higher in samples taken without a settling period than with either of the two settling periods. Electropositioned samples did not differ from non-electropositioned samples, except that benthic densities of leptophlebiid mayflies were significantly higher in electropositioned samples taken with a settling period than those without a settling period. The results of this study indicate that the length of settling period is of minor consequence when sampling hyporheic invertebrates (10-50 cm) and also provide little evidence of a benefit from electropositioning before freeze coring.