Detecting patterns in hyporheic community structure: Does sampling method alter the story?

Abstract

Hyporheic invertebrates were sampled in six small headwater streams draining pine, pasture, and native forest catchments. Sites were sampled in autumn and spring using three different hyporheic sampling methods (colonisation pots, pump sampling, and freeze-coring). Total invertebrate abundance and taxon richness differed significantly among sites on both sampling occasions for pump samples, whereas freeze-coring did not discriminate among sites, and pot samples showed significant differences in autumn, but not in spring. Differences among sites with respect to community composition were not consistent between sampling methods. Community ordination indicated that samples from colonisation pots tended to group together, whereas pump and freeze core samples were widely separated. Differences across land uses were also apparent (native forest sites formed a distinct cluster separated from pine and pasture sites). Results suggest that colonisation pots may provide a pathway for the entry of epigean organisms into the hyporheic zone even when hydraulic connectivity between surface and hyporheic zones is low. Invertebrate abundance was very low in pump samples, and this method also captured the fewest taxa of the three methods. The size bias known to exist with pump sampling techniques may restrict the usefulness of the method when comparing streams of differing hydraulic conductivity.

Trophic basis of production for a mayfly in a North Island, New Zealand, forest stream: Contributions of benthic versus hyporheic habitats and implications for restoration

“…Production was also high in hyporheic habitats, supporting the conclusion of Huryn (1996b) that hyporheic production may make an important contribution predator food webs and go some way to accounting for the Allen paradox (Allen 1951). Moreover, it reinforces the conclusions of Boulton et al (1997) and Scarsbrook & Halliday (2002) that intact hyporheic function, especially surfacehyporheic water exchange, is important for this species. Preliminary laboratory trials indicate that Acanthophlebia nymphs can tolerate high water temperatures (mean longevity at 25°C = 16 days; K. J. Collier unpubl.…”

“…Other studies indicate that Acanthophlebia populations 312 New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38 have difficulty coping with land-use changes that substantially increase siltation of interstitial habitats (Boulton et al 1997;Scarsbrook & Halliday 2002). Re-establishment of hyporheic function would appear to be an important process enabling this species to successfully recolonise and develop selfsustaining populations at restored sites on gravel-bed streams.…”

“…Preliminary laboratory trials indicate that Acanthophlebia nymphs can tolerate high water temperatures (mean longevity at 25°C = 16 days; K. J. Collier unpubl. data), suggesting that siltation of hyporheic habitats rather than water temperature increases may be the principal stressor for nymphs in developed catchments (Scarsbrook & Halliday 2002). However, impacts of water temperature on egg development and air temperature on adult survival can not be ruled out as factors limiting distribution.…”

“…The pots were 45-cm-long metal mesh tubes (diam. 11 cm, mesh size 1 cm) and contained three 15-cm-long plastic mesh baskets (mesh size 1 cm, volume 1500 cm 3 ) at 0-15,15-30, and 30-45 cm depths, as described by Scarsbrook & Halliday (2002). At the start of the study and following loss of pots during floods, baskets were filled with gravels removed from the same approximate depth in the streambed and washed through a 4-mm-mesh sieve.…”

“…Scarsbrook & Halliday (2002) reported that Acanthophlebia was common in the hyporheos of pine and native forest sites and at a pasture site with much of its upstream catchment area in native forest at Whatawhata, near Hamilton in the North Island, but was absent from a nearby site where the entire upstream catchment was in pasture. McLean (1967a) studied adult flight patterns of Acanthophlebia in a Waitakere Range stream near Auckland, and noted that adults swarmed 0-3 m above the streambed, especially over quieter pool areas in overcast drizzle conditions.…”