Habitat Monitoring and Marine Protection of Habitat-Forming Bryozoa, Otago, New Zealand
Hannah Mello1, Abigail Smith1, Anna Wood1, Emily Tidey1 and Dennis Gordon2, (1)University of Otago, Dunedin, New Zealand, (2)National Institute of Water and Atmospheric Research, Wellington, New Zealand
Abstract:
The bryozoans of New Zealand are diverse, well-described, and capable of creating ecologically-important three-dimensional benthic habitat. This structurally-complex benthic habitat hosts taxonomically rich fauna both on and around colonies. Economically important species in New Zealand, including tarakihi (
Nemadactylus macropterus), oysters (
Ostrea chilensis Küster, 1844), and blue cod (
Parapercis colias) are known to use bryozoan thickets as habitat and refugia. This association between commercial species and habitat-forming bryozoans has caused heavy fishing of bryozoan-dominated biogenic reefs. Historically, New Zealand bryozoan beds have been damaged and, in some cases, destroyed by anthropogenic activities such as anchoring and bottom fishing. Eliminating the use of destructive fishing practices through establishing non-extractive marine reserves may be an effective mechanism for promoting bryozoan recovery but has not been previously quantified Establishing good monitoring practices in new marine reserves is essential for measuring the success of protection in the future.
The present study addresses two aspects of habitat monitoring and marine protection of habitat-forming bryozoans on the Otago shelf, South Island/Te Waipounamu, Aotearoa New Zealand (45° 50’ S, 170° 50’ E, 60-110m): the effect of a 17-year voluntary trawl ban and baseline monitoring of a marine reserve proposed to target bryozoan thicket restoration. By comparing fauna recorded on benthic images from 2003 and 2019, we determined that a 17-year voluntary trawl ban has been ineffective at increasing the cover of habitat-forming bryozoans on the Otago shelf. Looking forward, the proposed marine reserve does include areas of highest bryozoan abundance within its boundaries. Future monitoring of the Otago shelf bryozoan thickets should include the investigation of the biology and ecology of habitat-forming species to better understand drivers of restoration and recovery.
