Some water bodies have been physically changed, but we do not know the extent or the impact this is having.
Fine sediment deposited on riverbeds is estimated to have increased, but we don’t know the national extent or impact this is having.
Wetland extent has greatly reduced and losses continue.
Cultural health is rated moderate at most tested freshwater sites.
Of the native species we report on, around three-quarters of fish, one-third of invertebrates, and one-third of plants are threatened with, or at risk of, extinction.
What is happening?
The health and mauri (life force) of some of our freshwater ecosystems declined because of human activities that reduced water quality, increased sediment yields, altered water flows, introduced pest species, and modified or lost habitats or the connections to habitats. These changes resulted in a decline in the populations of freshwater species, and many of our native freshwater plant, fish, and invertebrate species are now classified as threatened with or at risk of extinction.
Why does it matter?
Many of these species are endemic (found nowhere else in the world) so our biodiversity is nationally and internationally important. If the condition of freshwater ecosystems and habitats declines, this affects the species within them, and the economic, recreational, and cultural benefits we derive from them. The loss or decline in biodiversity can also have negative impacts on other species and the functions of the wider ecosystem.
The condition of our freshwater habitats and species are influenced by human activities on adjacent land, on river and lake margins, and within water bodies. Changes to flow regime, degraded water quality, pest species, channel modification, presence of barriers to fish migration, and increased sediment can also adversely affect biodiversity in these ecosystems.
This chapter covers: