appendix b final 2008 biological surveys of los angeles and long ...

7.0 Kelp and Macroalgae
site specific diver transects completed in winter and summer 2008. The occurrence of invasive
(“exotic”) species such as Sargassum muticum and Undaria pinnatifida was also assessed.
7.2 METHODOLOGY
7.2.1 Aerial Photography
Los Angeles and Long Beach harbor areas were photographed on February 15 and September
9, 2008, at a scale of 1:1600 by Focal Flight (Ojai, CA). Two cameras were used
simultaneously, one configured for natural color and one for near infrared (IR). Aerial imagery
was timed to coincide with the maximum low tide, optimum (high) sun angle, and low wind
conditions to optimize photographic resolution and feature interpretation. Images were
processed and geo-rectified to create a single mosaic of the entire survey area. A base image
was created from mosaics to evaluate the spatial extend of kelp and other macroalgae (the
same imagery was used to delineate eelgrass communities, see Chapter 8). Aerial imagery
was geo-rectified using 2005 orthographic images of the Ports to match shoreline features and
delineate the boundaries of the kelp and macroalgae surface canopy. The boundaries of the
kelp and macroalgae surface canopy were identified and mapped from the mosaic in an Arc
Map® Geographic Information System (GIS) format.
Kelp canopy extent, health, and dominant species within the project area were ground-truthed
along the perimeter of the surface canopies using a small vessel (13 ft. Boston Whaler) and
positional data collected using a Trimble® dips with an accuracy of ± 1 m. Kelp canopy
boundary data overlaid with IR aerial imagery were utilized to develop final maps and calculate
area estimates for kelp and macroalgae surface canopy.
7.2.2 Diver Surveys
To provide a characterization of macroalgae
species composition and vertical distribution,
20 transects (Figure 7.2-1) were surveyed by
divers in winter and summer 2008, based on
locations established during the 2000
baseline study (MEC 2002). Surveys were
performed by SCUBA divers using a modified
belt transect methodology. Transect
endpoints were recorded using a handheld
GPS unit and locations provided in Appendix
A. Two divers swam from the waterline (the
edge of the rock dike structures, known as
riprap, that form most of the shoreline of the
Ports) to the harbor floor following a fiberglass measuring tape. The divers recorded dominant
macroalgae species (presence/absence data) that occurred within one meter on either side of
the measuring tape. Thus, total species noted for each transect represents the total number of
dominant species, not an exhaustive list of all species present. This approach is consistent with
the methods used for the 2000 baseline study (MEC 2002). Each transect ended at the point
where algae was no longer found and the probability of encountering further algae on lower
portions of the transect was low, typically at the riprap/mud interface. Dominant macrofauna
were noted but not systematically quantified.
Observed algae were generally recorded by genus because either multiple species were
observed within a genus or because identification to species level was not possible during the
surveys for some specimens, instead requiring additional examination on the survey vessel or in
7–2 2008 Biological Surveys of Los Angeles and Long Beach Harbors
April 2010