Analysis of the conservation status of New Zealand freshwater invertebrates: temporal changes, knowledge gaps, impediments, and management implications

The 2018 conservation status assessment of freshwater invertebrate taxa was the most comprehensive to date. Of the Threatened and At Risk taxa in 2018 (177 taxa), 48 were listed as Nationally Critical, 14 as Nationally Endangered, 16 as Nationally Vulnerable, 10 as Declining, and 89 as Naturally Uncommon. Most taxa were listed as either Not Threatened (315 taxa) or required more information for assessment (Data Deficient; 178 taxa). Analyses of temporal changes in conservation status since 2002 revealed that the majority of changes were due to greater understanding of taxa distributions, rather than gains or losses in population sizes or area of occupancy. Insufficient data on taxa distributions, along with a lack of autecological information, are two of the major knowledge gaps facing freshwater invertebrate conservation in New Zealand. Further impediments to conservation include (i) a lack of systematics research, (ii) a large number of species remain undiscovered and undescribed, and (iii) the status and trend of populations is unknown for most taxa. We also provide an analysis of the habitats that harbour many of the rarer taxa. Finally, we conclude by recommending a number of actions that should, collectively, help fill these knowledge gaps and address these issues.