Groundwater Invertebrates

Did you know that there is an entire community of invertebrates that live below the ground surface in the groundwater aquifers? The majority of them are small colourless and blind crustaceans that have lost the ability to swim. Some, however, grow up to 15–25 mm long and are good swimmers. They live in the tiny crevices and spaces between the stones within aquifers and feed on biofilms (bacterial slime layers).

Little is known about the groundwater invertebrates that are found living in Marlborough’s aquifers. Studies of other aquifers around New Zealand have found that many of the species are unknown to science, lack scientific names, and are endemic to specific areas. They are thought to be an important part of the purification of groundwater as they stop the biofilms clogging the tiny pore spaces of the aquifer so that the aquifer keeps flowing.

The Marlborough District Council is in the process of developing a groundwater invertebrate monitoring programme that will increase the knowledge of the biodiversity of Marlborough’s aquifers.

According to Dr M Scarsbrook, previously of NIWA, representatives of the Crustacea group Syncarida have been found locally. An invertebrate found by Marlborough District Council freshwater ecologist Peter Hamill in a shallow well on the north bank of the Wairau River in 2006 was identified by the Cawthron Institute as Paracrangonyx Winterbourni.