Small-scale patch complexity, benthic invertebrate colonisation and leaf breakdown in three headwater streams in Bay of Plenty, New Zealand


We assessed the effects of patch complexity on benthic macroinvertebrate colonisation and leaf breakdown in three headwater streams in the Kaimai Range, New Zealand. We used three patch types: complex, disturbed, and unaltered control patches, and measured colonisation of macroinvertebrates and leaf breakdown rates within each patch. We hypothesised colonisation and breakdown would be highest in the complex patches and lowest in disturbed patches. With the exception of percentage of total shredders, no differences were found in macroinvertebrate diversity or community structure and no treatment effect was evident for leaf breakdown rates. While this may suggest no influence of patch complexity on leaf breakdown, we cannot discount unmeasured site-specific influences, such as a high flow event, which occurred during the treatment period, as clear differences were evident between the three streams. Higher spatiotemporal replication and more appropriate seasonal sampling would be required to further explore this relationship.

New Zealand Journal of Marine and Freshwater Research
Jonathan D. Tonkin
Senior Lecturer & Rutherford Discovery Fellow