Coastal Diptera species and communities and their geographic distribution in Aotearoa|New Zealand

The coast provides an important habitat for insects throughout the world. Some insect taxa are entirely dependent on this continuous but narrow strip of habitat between the land and sea, despite the challenging environmental conditions. In Aotearoa|New Zealand (hereafter Aotearoa), the coastal environment is extensive and varies enormously. Aotearoa is also home to a diverse and predominantly endemic Diptera fauna of roughly 5500 species, and a small but significant proportion of these are found along the coast. Here we provide the first extensive survey of Aotearoa’s coastal flies, and describe how the diversity, richness, and abundance of specialised wrack-inhabiting communities vary. Overall, we recorded 257 different species collected from 109 sites from around Aotearoa’s three main islands, with highest abundance, species richness and diversity all found at South Island sites. Our surveys are estimated to have captured over 80% of the species occupying the seashore, and 100% of the wrack specialist community, for which we identified a country-wide baseline community. This study has provided new and interesting insights into the distribution and diversity of flies in Aotearoa. It also highlights the importance of carrying out broad community surveys to capture and improve our understanding of our local fauna.