By Laura Wakelin, Technical Advisor in DOC’s Marine Ecosystems Team.
In 2015 DOC was part of a fantastic collaborative project to produce high resolution maps of the marine environment surrounding Kapiti Island in the Wellington region, including Kapiti Marine Reserve. The project is part of DOC’s marine reserve research and development work, part funded through DOC’s partnership with Air New Zealand.
Few people are aware of the stunning showcase of extremely diverse and abundant marine habitats and species beneath the surface of Kapiti Island. Kapiti Marine Reserve is one of our Coastal Gem’s and protects a significant portion of these habitats. This creates a continuous area of protection between Kapiti Island Nature Reserve and Waikanae Estuary Scientific Reserve on the mainland.
Despite the importance of the area, the Kapiti Island marine environment had never been mapped using state of the art technology. Until recently, outdated information was being used to show us what the seabed surrounding the island looked like.
In May-June of 2015, DOC teamed up with the National Institute of Water and Atmospheric Research (NIWA), Victoria University of Wellington (VUW) and Land Information New Zealand (LINZ), with support from Greater Wellington Regional Council and Ngati Toa Rangatira, to map the seabed around Kapiti Island.
Over 14 days (spread across a couple of months due to horrendous weather) a small crew used a Multibeam Echo-Sounder to learn more about an area of the seafloor approximately 50 km2 around the island, both inside and outside Kapiti Marine Reserve. Attached on the hull of NIWAs vessel Ikatere, this sophisticated bit of equipment sends out beams of sound waves to the seafloor, which bounce back to a receiver on the ship, providing information about different components of the seabed. The data we receive from the Multibeam is very useful for constructing maps of the habitat.
In November, the Marine Ecosystems Team at DOC and divers from VUW set out to collect more specific information needed to build a bigger picture of the marine environment. This included using underwater video equipment and divers equipped with underwater cameras to confirm what the seabed ‘truly’ looked like and comparing it to the data from the previous Multibeam survey.
From rocky reefs covered in seaweed forests and sponge gardens, to soft sediments full of scallops, horse mussels and crabs, the team surveyed specific sites across a full range of habitats. There were some unexpected finds, including the exciting discovery of acres and acres of the anemone Actinothoe albocincta blanketing the seafloor; a very cool phenomenon that none of the team had encountered before.
We also confirmed the presence of rhodoliths (maerl), rare coral-like seaweeds that only grow in clean, clear water and create 3-dimensional structure that other organisms use to live and reproduce on. Extremely little is known about this type of habitat throughout New Zealand and rhodolith beds are internationally recognised as being of conservation importance.
We are currently looking through the data from the November fieldwork and will continue work with NIWA, VUW and LINZ to produce a suite of maps of the Kapiti marine environment, including interactive maps using some of the video footage we collected. We can’t wait to see the amazing final products, watch this space!