Cover • Principle Findings • Introduction • Methods & Results • Data Summry • Discussion/Conclusion • Glossary • Literature Cited Figures & Tables • 1999/2000 Kelp Bed Maps

Glossary

Kelp Bed Canopy An aggregation of surface kelp plants in close proximity to each other which produced a consistent infrared return on the imagery, such that individual plants were indistinguishable when projected at mapping scale (1 :24,000) Kelp Bed Qualitative Canopy Area The geoqraphic (spatial) extent of individual surface kelp plants and canopies, as fully rendered from the original imagery. Each visible individual kelp plant and canopy was hand transferred to the "canopy area" maps, and represented by black-shading wherever present. Areas within the perimeter of the canopy that did not contain kelp were left un-shaded. This index depicted the actual appearance of the surface kelp canopy, as viewed on the original imagery. Kelp Bed Quantitative Canopy Area The numeric extent (sq. mi.) of individual surface kelp plants and canopies. Each qualitative canopy area map was scanned into the image processing system at full scale (1:24,000), and subsequent screen "pixel counts" conducted. All "black-shaded" pixels that represented actual kelp at the surface were counted, individual pixel area determined, and a quantitative kelp canopy area established. This index represented, numerically, the actual extent of the surface kelp canopy, as mapped from the original imagery. Kelp Bed Qualitative Planimeter Area The geographic (spatial) extent of the surface keip canopy contained within its own perimeter, assuming continuous kelp coverage within. Since the surface kelp resource was composed of individual plants and established canopies; this measurement systematically defined the perimeter and subsequent enclosed area of this plant assemblage. This value depicted kelp canopy areal extent in slightly different terms than "canopy area", as previously defined, and served three purposes in this analysis: 1) it allowed comparisons of current and historic estimates of keip resource abundance, which utilized similar "perimeter" estimation methods, 2) it allowed an understanding of the sea surface area that was actuaily occupied or influenced by the kelp canopy, and 3) it allowed a measurement of keip canopy density (see "kelp bed relative density index"). Quaiitative pianimeter area, by kelp bed number, was established by computer enhancement of each scanned "canopy area" map. This methodology systematically established perimeter polygons around each kelp canopy, and included all kelp plants inside the polygons that were within 50 meters of each other, giving each plant a 25 meter "radius of association" (1 mm at the 1:24,000 mapping scale). Within the analysis software ("Global Lab Image"-V3.1-Data Translation), individual kelp plants and canopies within were "dilated" (expanded) with a "5x5" pixel "structuring element", thereby adding a 25 meter radius of kelp to each existing kelp pixel. Individual kelp plants within 50 meters of each other became part of the same perimeter, while plants greater than 50 meters apart retained discrete perimeters. Within established canopies, this transform had the effect of defining the canopy perimeter 25 meters beyond that visually apparent on the "canopy area" maps, as well as filling in the all of the "holes" in kelp coverage within the canopy. This computer synthesized value is spatially similar to that obtained by using a hand planimeter to determine kelp canopy areal extent, and hence the name. Many environmental surveys have used planimeter areas to describe resource abundance, since prior to computers, this was all that was available. In addition, by the nature of the process, area statistics from other hand diqitized kelp resource maps (for data entry into a geographic information system; see definition), will closely approximate the quantitative planimeter area (see definition), thereby allowing comparisons. This index is always larger than the kelp "canopy arean, which is a depiction and measurement of the sea surface area actually occupied by visible kelp plants. In addition to allowing comparisons with both historic (planimeter derived), and computer (digitizer derived) data, planimeter area measurements more accurately depict the extent, or sea surface area occupied, by kelp canopy species that have more irregular distributions (dense canopies in some areas and sparse areas containing individual plants in others). Nereocystis sp. canopies are frequently observed with this growth pattern, and their prominence underrepresented by a strict "canopy area analysis only. Kelp Bed Quantitative Planimeter Area The numeric extent (sq. mi) of the qualitative planimeter area (see glossary). Each quantitative planimeter area, by CDF&G canopy number was scanned into the image processing program, and a screen "pixel count" conducted. All pixels within the individual perimeters were counted, individual pixel area determined, and a quantitative canopy planimeter area establ ished . Kelp Bed Relative Density Index (RDI) The percentage of the planimeter area that actually contained surface kelp plants. This index was calculated by dividing the canopv area by the ~animeter area and approximated the probability of encountering kelp at a random point within the canopy perimeter. This vaiue approaches "1" for very dense canopies and "O" for very sparse canopies. The measurement is independent of canopy size1 and a good indicator of changes in density over time. In considering the relationship between canopy area and planimeter area, severai examples underscore this basic relationship, and subsequent multi-year trends. Canopy Area (sq. mi.) PlanimeterArea (sq. mi.) Relative Density (RDI) Interpretation 1.0 2.0 5 1.0 sq. mi. of kelp is contained within 2.0 sq. mi. of the sea surface that it occupies (prob. of encountering kelp within perimeter = .5) 5 2.0 25 5 sq. mi. of kelp is contained within 2.0 sq. mi. of the sea surface that it occupies (prob. of encountering kelp within perimeter = .25) Can. Chg. Plan. Chg Den. Ch Interpretation - Multi-Year Trends 1.0 to 1.0 2.0 to 2.0 0.5 to 0.5 Kelp resource area (canopy area), spatial extent (plan. area), and density (RDI) stable over time 1.0 to 1.5 2.0 to 2.0 0.5 to 0.75 Increased resource area within similar spatial extent at inc. dens. 1 0 to 2 0 2.0 to 4.0 0.5 to 0.5 Inc. resource area and spatial extent at similar densities 1 0 to 2 0 2 0 to 3 0 0.5 to 0.66 Inc. resource area and spatial extent at increasing densities 1.0 to 1.5 2.0 to 4.0 0.5 to 0.38 Inc. resource area and spatial extent at decreasing densities 1.0 to 0.5 2.0 to 2.0 0.5 to 0.25 Dec. resource area within similar spatial extent at dec. density 1.0 to 0.5 2.0 to 1.0 0.5 to 0.5 Dec. resource area and spatial extent at similar densities 1.0 to 0.5 2.0 to 1.5 0.5 to 0.33 Dec. resource area and spatial extent at decreasing densities 1.0 to 0.5 2.0 to 3.0 0.5 to 0.16 Dec. resource area within inc. spatial extent at dec. densities Geographic Information System (GIS) A computer software plafform designed to facilitate the assembly and analysis of diverse data sets pertaining to specific geographic areas using spatial locations of the data as the basis for the information system

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