MacFarlane, R. (2012). Terrestrial invertebrates from the salt marshes of the Avon-Heathcote Estuary/Ihutai and Pegasus Bay.
This report was commissioned by the Avon-Heathcote Estuary Ihutai Trust in 2012 to investigate the terrestrial invertebrate fauna (insects, spiders and mites) living in tidal and estuary margin vegetation in the Ihutai estuary and Ashley River in Pegasus Bay. The purpose of the report was to fill gaps in collective knowledge of Canterbury estuary and lagoon invertebrates to aid their conservation management. To do this, vegetation beating, net sweeping, and pan traps were used in three main vegetation types: saltmarsh ribbonwood (Plagianthus divaricatus), jointed rush (Apodasmia similis), and saltmarsh meadow (mainly comprising Sarcocornia quinquiflora, Plantago coronopus and Sellieria radicans). The pan traps were modified to overcome the difficulties of collecting in tidal habitats and were very efficient and reliable.
Overall, this survey revealed several new insect herbivores and parasite links (eg; Delphacidaie a new host of Strepsiptera), as well as the specific plant parts that herbivours feed on. It also revealed the importance of temporary influxes of breeding adult insect populations as estuary prey species, that the litter layer provides nourishment for diverse fauna, and that tactical collecting from adjacent habitats is important for determining fauna origins. Saltmarsh ribbonwood had the highest invertebrate diversity. To further fill national knowledge gaps, the report recommended further investigation of invertebrate diversity along Canterbury coastlines.