Large river 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.

  • Fish – electrofishing boat

  • Macroinvertebrates – a range of approaches have been compared:

    • 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. Link to journal.

    • 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 shorezone habitats including macrophytes, wood, tree roots, and sand-gravel beaches.

    • rivers rivers rivers
      Air-lift sampler
      Coir sampler
      Hester Dendy

Current projects

  • Testing functional indicators for monitoring the ecological condition of large rivers (Roger Young & Joanne Clapcott, Cawthron Institute).

  • Macroinvertebrate indicators for non-wadeable rivers (Kevin Collier).

References

Clapcott J, Young R 2009. Spatial and temporal variation of functional indicators in Waikato rivers. Prepared for Environment Waikato. Cawthron Report No. 1693. 24 p.

Clapcott J; Young R 2008. Spatial variation of functional indicators in the Waikato River. Environment Waikato technical report no. 2008/32. Cawthron Institute, Nelson. Read report

Back to top