4.3 Biological Unit Data and Database Structure

Biotic mapping in the estuary uses a combination of the WREC system for the upper estuary where rooted, vascular vegetation dominates, and the BC Biological Shore-zone Mapping System for the marine-dominated areas. Often the lower limit of the shrubs, grasses and halophytes like Salicornia of the upper estuary will be present as a distinct line between the meadows and the tidal flats in the lower estuary (Day et al., 1989, Adam, 1993.).

Depending on the objectives and scale of the estuary mapping, two options are suggested for mapping the biota of the upper estuary. If site series information is not available or if the survey is a general overview, then the WREC class is used for the mapping. In a more detailed survey, the site series is mapped. An overview of the WREC classification is described in Section 1.2.3 and further background about the system is described in MacKenzie and Banner (in preparation). The codes and definitions for each of the classes and site series for upper elevations of estuaries are discussed below.

Mapping for the marine-dominated lower estuary is based on the groups of species called `bio-bands'. The bio-band descriptors were developed as a way to summarize aerial video observations and are approximately equivalent to site series, in that a number of dominant species are used to identify an assemblage of species at certain physical habitats (see overview in Section 1.2 and Searing & Frith (1995) for more detail). The species which comprise the band are determined from field verification.

Biotic polygons in the estuary will be mapped based on the visible macrobiota. Each of the biotic polygons identified will be coded to include a number of attributes (Table 4). These attributes are determined in pre-typing of the study area, based on aerial photos or other remotely-sensed imagery and then are verified during the field survey. Polygon boundaries may be adjusted based on the field verification of the biota present.

Field plots are an important component of the mapping of the biotic polygons. Details of the field plots are recorded in the Biological Site Form Database discussed in Section 4.5.

Table 4 - Description of the Biological Unit Database.

Field Name	Type	Width of Field	Description
EstuaryID	Alphanumeric	14	Unique identifier for Estuary (eg. SEYMWSD0001890x) from BC Watershed Atlas.
Bio_ident	Alphanumeric	13	Biological unit identifier from BC Biological Shorezone Mapping System (if available).
BiounitID	Numeric	2	Unique identifier of estuary biological polygon.
WREC	Alpha	3	Only applies in the upper intertidal where rooted shrubs, graminoids, forbs, ferns, bryophytes, aquatics may occur. The class is a summary of physiognamy of groups of the site series. There is no equivalent for the marine-dominated biota mapped in the mid- to lower intertidal. See Table 5.
Sseries	Alpha	225	In the upper intertidal, use the WREC site series (if available) which is a species assemblage, identified by one, two or three dominant species. Site series for estuaries are currently under development by MacKenzie et al. In the mid- to lower intertidal, use the bio-band which describes a species assemblage of the dominant species of sessile macrobiota (both vegetation and fauna). See Tables 6 - 7.
Dom1	Alpha	7	Species name of the species with the highest cover in the polygon. If species identification is not possible, the three species name fields may be left blank and only the general summary of biota (class, site series or bio-band) coded for the polygon. Dominant species (1, 2 and/or 3) can then be verified during field survey.
Cover1	Numeric	2	% cover value of species 1 (estimated in pre-typing if possible, verified in field survey)
Dom2	Alpha	7	Species name of the species with the next highest cover in the polygon (verified during field survey)
Cover2	Numeric	2	% cover value of species 2 (estimated in pre-typing if possible, verified in field survey)
Dom3	Alpha	7	Species name of the species with the next highest cover in the polygon (verified during field survey)
Cover3	Numeric	2	% cover value of species 3 (estimated in pre-typing if possible, verified in field survey)
Mapper	Alpha	25	Mapper name(s) (last name, first name)
Date	Alpha	8	Date dd/mm/year
Notes	Alpha	255	Other information