Animals of New Zealand wetlands

New Zealand wetlands provide many ecosystem services, but their extent has declined by more than 90% since human arrival, highlighting the urgent need to identify and protect them. Wetland delineation in New Zealand depends primarily on vegetation, supported by soil type and hydrological indicators. However, this current approach only partially fulfils the legal definition of wetlands in the Resource Management Act 1991, which requires that an area “support a natural ecosystem of plants and animals that are adapted to wet conditions”. Although significant progress has been made in characterising wetland vegetation, far less is known about the diversity, distribution, and abundance of New Zealand wetland animals. Here we review the current state of knowledge about animals supported by New Zealand wetlands, describe their adaptations to wet conditions, and discuss implications for wetland delineation and policy enforcement. Overall, we consider that animals adapted to wet conditions are ubiquitous in habitats that otherwise satisfy current wetland delineation protocols. Major animal groups include macrofauna such as birds and fish, and invertebrates such as annelids, flatworms, nematodes, rotifers, insects, crustaceans, and molluscs. Some of these taxa are widespread, abundant, and can survive extended dry periods and other extreme conditions, suggesting that at least some wet-adapted animals are likely to be present in all delineated wetland ecosystems (based on plants, hydrology, and soils), regardless of their dryness, degradation and damage. However, our review identified major gaps in our fundamental knowledge of New Zealand wetland animal communities, especially for intermittent wetlands. Future work should survey key animal groups across a range of wetland classes throughout New Zealand and develop robust methods to detect and monitor these fundamental but currently overlooked animal groups.