Marine habitat mapping in support of Marine Protected Area management in a subarctic fjord: Gilbert Bay, Labrador, Canada

This paper presents an approach that allows
production of benthic substrate and habitat maps in fjord
environments. This approach is used to support the
management of the Gilbert Bay Marine Protected Area
(MPA) in southeastern Labrador, Atlantic Canada. Multibeam
sonar-derived bathymetry, seabed slope, and acoustic
reflectance (backscatter) were combined using supervised
classification methods and GIS with ground-truthed benthic
sampling in order to derive maps of the substrates and main
benthic habitats. Six acoustically distinct substrate types
were identified in the fjord, and three additional substrate
types without a unique acoustic signature were recognized.
Ordination by multidimensional scaling and analysis of
similarity generalized these to four acoustically distinct
habitat types. Greatest within-habitat (alpha) diversity was
found in the coralline-algae encrusted gravel habitat.
Greatest between-habitat (beta) diversity was found in the
management Zones 1 and 2, which have the highest level of
protection. The study confirmed that the zoning plan for the
MPA, which was designed to protect spawning and juvenile
fish habitat for a local genetically distinct population of
Atlantic cod, afforded highest levels of protection to areas
with highest habitat diversity.