Sampling methodologies

Large rivers pose a number of challenges for quantifying the distribution and abundance of biota such as macroinvertebrates and fish. Sampling is typically hampered by the physical difficulties and dangers associated with accessing deep and fast-flowing water, and the complexity and scale of habitats that occur within them. Moreover, the large size of these rivers presents challenges in capturing the range of variation present when assessing biodiversity and species distributions. No single sampling method will achieve all goals as each one has advantages and disadvantages (see table for macroinvertebrates), so a combination of methods is often best.

Completed projects

LERNZ researchers have conducted an international review of approaches to sampling macroinvertebrates in large rivers, and have tested various approaches, including:
Air-lift sampler - operates using compressed air and can access benthic habitats from 2-5 m deep

  • Coir samplers - provides a standard structure typical of root mat habitats; can be deployed over a range of depths.

  • Multiplate samplers - also referred to as Hester-Dendy samplers, these samplers can be made from perspex or wood. They provide flat surfaces and spaces between plates for colonisation

  • Sweep netting - can be used to sample shore-zone habitats including macrophytes, wood, tree roots, and sand-gravel beaches.

In addition we have compared various methods for sampling shore-zone fish communities in contrasting habitats (beach, willow, riprap). LERNZ also has an electric fishing boat for sampling fish in non-wadeable habitats (link to Invasive Fish theme - Control and monitoring methods - Electric fishing boat).

  • Collier K.J.; Hamer, M.P.; Moore S.C. 2014. Littoral and benthic macroinvertebrate community responses to contrasting stressors in a large New Zealand river. New Zealand Journal of Marine and Freshwater Research in press.

  • Clapcott, J.; Pingram, M.; Collier, K.J. 2012. Review of functional and macroinvertebrate sampling methods for non-wadeable rivers. Cawthron report no. 2222, Cawthron Institute, Nelson.

  • Collier, K.J.; Hamer, M. 2011. Artificial substrate monitoring of macroinvertebrates in the Waikato River: 25 years on. Waikato Regional Council technical report 2011/25. Waikato Regional Council, Hamilton.

  • Collier, K.J.; Hamer, M.; Chadderton, W.L. 2009. A new artificial substrate for sampling deep river macroinvertebrates. New Zealand Natural Sciences 34: 49-61.