Research Document - 2015/036

Mapping areas of high phytoplankton biomass in the offshore component of the Scotian Shelf Bioregion: A remotely-sensed approach

By C. Fuentes-Yaco, M. King, and W.K.W. Li

Abstract

The main purpose of this document is to identify phytoplankton-rich areas in the Scotian Shelf Bioregion, designated as areas of persistent elevated chlorophyll concentration detected by remote sensing. Regions that contain comparatively higher biomass than surrounding areas are considered Ecologically and Biologically Significant Areas under the Fisheries and Oceans Canada (DFO) Aggregation criterion and possibly the Convention on Biological Diversity Biological Productivity criterion, so they can be considered in Marine Protected Area network development for the Scotian Shelf Bioregion (DFO 2014). The study area was subdivided based on physical and biological conditions; it comprises the mid- and outer-Scotian Shelf separated into western, central and eastern sub-areas, together with the slope, rise and abyssal plain which integrate the off-shore region. MODIS-Aqua weekly composites of chlorophyll at 1.5 km spatial resolution for the time period 2003 to 2013 were processed at the Remote Sensing Unit of the Bedford Institute of Oceanography. Climatology composites for each of the forty-eight weeks from January to December were the main source of data (a forty-eight week convention has been used for analytical purposes). Maps of high and persistent phytoplankton biomass regions were produced at annual and seasonal temporal resolution; frequency histograms of the number of pixels in decile classes of persistent elevated chlorophyll concentrations complete the description of results. The results distinguish between different zones on the mid- and outer-Scotian Shelf, where traditional fisheries are located. The outward open-water region (rise and slope) stands out as an environment recurrently inhabited by large pelagic fishes and mammals, such as tuna and whales.

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