A spatial framework for representing nearshore ecosystems Edward J. Gregr a,⇑ , Joanne Lessard b , John Harper c a SciTech Environmental Consulting, 2136 Napier Street, Vancouver, BC V5L 2N9, Canada b Department of Fisheries and Oceans Canada, Nanaimo, BC V9T 6N7, Canada c Coastal and Oceans Resources Inc., Victoria, BC V8Z 3B8, Canada article info Article history: Available online xxxx abstract The shallow, coastal regions of the world’s oceans are highly productive ecosystems providing important habitat for commercial, forage, endangered, and iconic species. Given the diversity of ecosystem services produced or supported by this ecosystem, a better understanding of its structure and function is central to developing an ecosystem-based approach to management. However this region – termed the ‘white strip’ by marine geologists because of the general lack of high-resolution bathymetric data – is dynamic, highly variable, and difficult to access making data collection challenging and expensive. Since substrate is a key indicator of habitat in this important ecosystem, our objective was to create a continuous sub- strate map from the best available bottom type data. Such data are critical to assessments of species dis- tributions and anthropogenic risk. Using the Strait of Georgia in coastal British Columbia, Canada, as a case study, we demonstrate how such a map can be created from a diversity of sources. Our approach is simple, quantitative, and transparent making it amenable to iterative improvement as data quality and availability improve. We evaluated the ecological performance of our bottom patches using observed shellfish distributions. We found that observations of geoduck clam, an infaunal species, and red urchins, a species preferentially associated with hard bottom, were strongly and significantly asso- ciated with our soft and hard patches respectively. Our description of bottom patches also corresponded well with a more traditional, morphological classification of a portion of the study area. To provide sub- sequent analyses (such as habitat models) with some confidence in the defined bottom type values, we developed a corresponding confidence surface based on the agreement of, and distance between obser- vations. Our continuous map of nearshore bottom patches thus provides a spatial framework to which other types of data, both abiotic (e.g., energy) and biotic, can be attached. As more data are associated with the bottom patches, we anticipate they will become increasingly useful for representing and devel- oping species-habitat relationships, ultimately leading to a comprehensive representation of the near- shore ecosystem. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The nearshore subtidal region (0–50 m depth) is a highly pro- ductive ecosystem providing both permanent and transitory habi- tat for commercial (e.g., rockfish, salmon), forage (e.g., sandlance, herring), endangered (e.g., abalone) and iconic (e.g., kelp, sea ot- ters) species. Given the number of ecosystem services that are pro- duced or supported by this ecosystem, a better understanding of its structure and function would clearly benefit any ecosystem-based approach to management (EBM). As the transition zone between the terrestrial and marine environments, it is also the region most directly affected by urbanisation and up-land influences. The near- shore is therefore also key to understanding the land-sea interface, and for managing anthropogenic risk and cumulative impacts. The value of spatially continuous, accurate maps of this ecosys- tem is widely recognised by managers and conservationists (Cogan et al., 2009; DFO, 2010; Shumchenia and King, 2010). However, the nearshore – termed the ‘‘white strip’’ (Fig. 1) by marine geologists because of the lack of high-resolution bathymetric data – is a dy- namic, highly variable, and poorly accessible ecosystem, making data collection difficult and expensive. Characterisation of this re- gion is thus hindered by a general lack of continuous datasets (DFO, 2010). Acoustic multi-beam methods provide high resolution bathym- etry and can be used to derive bottom type (Anderson et al., 2008; Kvitek et al., 1999; MESH, 2010). However, their application in shallow waters is time-consuming. In British Columbia (BC), the time required to map the entire nearshore using multi-beam acoustics is measured in decades to centuries (Heap and Harris, 2011). Furthermore, only depth is obtained reliably, since the col- lected backscatter data must be post-processed into a model of bottom type. 0079-6611/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.pocean.2013.05.028 ⇑ Corresponding author. Tel.: +1 604 612 8324. E-mail address: ed@scitechconsulting.com (E.J. Gregr). Progress in Oceanography xxx (2013) xxx–xxx Contents lists available at SciVerse ScienceDirect Progress in Oceanography journal homepage: www.elsevier.com/locate/pocean Please cite this article in press as: Gregr, E.J., et al. A spatial framework for representing nearshore ecosystems. Prog. Oceanogr. (2013), http://dx.doi.org/ 10.1016/j.pocean.2013.05.028