Cover • Principle Findings • Introduction • Methods & Results • Data Summry •
Discussion/Conclusion • Glossary • Literature Cited
Figures & Tables • 1989/1999 Kelp Bed Maps
Materials and Results
The methodology utilized in this kelp resource
inventory, to document the extent of the kelp
resource within the MBNMS, was divided into four
phases: The methods utilized in this current survey were
similar to those used in the 1989 inventory, to
ensure data compatibility and comparability with
this and other subsequent studies. Although the
defined scope of this study was limited to the
measurement of current resource abundance, specific
comparisons were made with the last previous
systematic analysis (1989), to document short-term
changes in kelp canopy extent 1) Kelp Canopy Aerial
Photography The methodoiogy related to obtaining
high-quallty Imagery of the tully deveioped 1599
California coastal kelp resource was divided
into two sections: 1) survey timing, imaging,
and logistic considerations, and 2) photography
of the 1999 kelp resource. The seasonal timing, photographic scale,
and flight parameters of this aerial survey
were established, as in previous surveys, to
systematically obtain imagery that best
represented the maximum extent of the current
kelp resource. Acceptable "survey windows"
were chosen for the aerial over-flights in
response to several biologicai (seasonai
timing of maximum canopy development),
physical (tidal level, weather and sea state)
and logistic factors (length of survey
range). Seasonal timing of maximum kelp canopy
development was the major biological factor
involved in scheduling this resource survey,
and established the criteria around which all
other iogistic decisions were made. Within
California, it has been observed, that the
maximum extent of canopy forming kelp species
occurs in August through October, with
maturity of the Nereocystis canopy
determining the beginning of this "biological
window", and early season storms determining
the end. Within this three month period, several
acceptable "tidal windows" were selected
(utilizing NOM tide tables for Monterey and
San Simeon) that would allow the aerial
imagery to be obtained at tidal levels of
less than +1.G' MLLW. Once the tidal windows
were established, the actual survey was
conducted during the first window that had
acceptable associated environmental
conditions. These conditions included
adequate ceiling and visibility (>10,000' MSL
and five miles), surface winds less than ten
knots, sea/sweli less than five feet, and a
sun angle of greater than 30 degrees from
vertical. In California, changeable weather
(especially coastal fog, high winds and sea
state) can be a major limiting factor on
survey timing, and can frequently reduce the
number of acceptable survey days in a given
season to less than twenty. During the
previous (1989) survey, the aerial imagery
was obtained within these optimum biological,
tidal, and environmental windows, thereby
allowing meaningful comparisons of seasonal
kelp resource areal extent. The aircraft altitude (9,500' MSL) and
photographic scale (1"=3,217') used for these
surveys was selected to provide a good
balance between resource resolution and
rendition on the imagery, the selected
base-mapping scale (1:24,000), and the
overali length of the survey area (276
miles). At this altitude and photographic
scale, the entire survey range (Cambria to
Rocky Point) could be accurately recorded,
under optimum conditions, during two
low-tidal periods. Considering the changeabie
nature of California coastal weather; this
methodology allowed the maximum utiiization
of the few optimum survey dates. With regards
to resource resoiution on the imagery; ground
truth measurements have indicated that the
smaiiest kelp "dots" on the 1 :24,000 scale
maps (approximately the size of a text
"period" from this document), represent as
few as six surface stipes from a single
Macrocystis kelp plant. The film used on this survey was 70 mm
Kodak color infrared - type 2443, the
accepted standard for use in documenting the
areal extent of marine surface vegetation.
Its ability to increase the contrast between
kelp and the surrounding water, without
sacrificing resoiutiGn, made it ideal for
resource surveys of this type. Despite this
abiiity, infrared film does have iimitations
regarding its utility in recording
sub-surface coastal kelp canopies. Due to its
poor water penetration properties of
approximateiy two feet (Helgeson 1970); this
fiim wiil not record keip stipes that are
significantiy puiled beiow the surface due to
high winds and seas, high tides, and tidai
currents. This especiaiiy affects sparse
Nereocystis canopies, which can be compietely
submerged by the above factors (especiaiiy
tidai currents), and not recorded on the
imagery. Carefui attention to survey timing
that corresponded with acceptabie winds,
seas, and the "time of the low tide" at each
coastal location, was necessary to insure
accurate canopy rendition on the imagery. 2) Photography of the 1999 Kelp
Resource When the biological, tidal, imaging, and
logistic factors were considered together,
three possible "optimum survey windows" were
established for the 1999 kelp resource
inventory: 1) September 24-27, 2) October
7-10, and 3) October 23-27,1999. Aerial photography of the 1999 kelp
resource was accomplished on October 7 and 9,
1999, during the second optimum survey
window. Calm winds, low seas, and mostly
clear skies were present throughout the
survey range on both dates, with the
exception of patchy coastal fog from Pt. Sur
north to San Francisco on October 7. A
summary of associated environmentai
conditions, in addition to visual
observations taken during the survey were
presented in fiqures 1.1 and 1.2. Continuous, sequential, vertical
photographs (20%-30% overlap) were taken from
9,500' MSL (75mm lens) of the coastal zone
between Point Estero and Point Sur on October
7, and from Point Sur to Rocky Point on
October 9. Approximately 20% shoreline was
included on each image to facilitate accurate
projection onto the base line maps. Larger
canopies, that were not fully recorded on the
initial "in-shore" photographic transect,
were referenced on parallel "off-shore"
flight lines. Each new transect was
"side-lapped!' by 30%40% with those in-shore,
to facilitate the accurate mapping of these
off-shore canopies. The imagery from each of the survey dates
was processed normally, judged of excellent
quality, and allowed the complete and
subsequent mapping of the coastal kelp
canopies within the study range. This indexed
imagery was presented as: "California Coastal
Kelp Resources - Monterey Bay National Marine
Sanctuary Summer 1999 -Aerial SurveY Imaaery"
- Binder 1/1 "Bolinas Lagoon to Pt.
Estero". 2) Qualitative Kelp
Bed Canopy Mapping Kelp bed mapping was accomplished in two phases:
A) base-line map preparation, and B) kelp bed
canopy area mapping and indexing. The base-line maps for this coastal kelp
survey were originally designed for the 19&9
inventory, and subsequently used again in this
effort. This base-map series presents an
accurate and continuous depiction of the
California state coastal zone from the Oregon to
the Mexican borders, including southern
California offshore islands, and allowed the
systematic mapping of the sanctuary-wide
resource. Eighty-three contiguous base-line maps
~24"x36", scale 1:24,000) were made of the
California coastal zone using USGS 7 1f2'
quadrangle maps (scaie 1:24,000) as a reference.
These maps offered extensive shoreline detaii,
high accuracy, and continuous coastal coverage
for the entire state. Each of the "quad" maps
was copied on a calibrated photocopier (Sharp
"8400"). The contiguous 'Ishoreline'' portions
of each of the map copies were then assembled
together, and became the land reference on each
of the base maps. All standard detail from these
USGS maps was preserved, including prominent
shoreline features, offshore rocks, rivers,
beaches, rocky intertidal habitat, towns,
harbors, and topographic relief. In addition,
the CDF&G kelp bed numbering system, which
divides the state-wide kelp resource into
discrete beds based on bearings from key
geographic points, was also included. The coastal zone, within the MBNMS, from
Rocky Point to Cambria Rock, was located on maps
27 - 44 within this map set. These maps were
indexed by map number (table 1), and maP name
(table 2), and CDF&G numbered kelp beds
present on each map page were also included. To
aid in orientation and facilitate the "field
use" of the maps, prominent ~eo~raphic features
were listed alphabetically in tabular form
(table 3), with cross-references to the map name
and number where they were found. B) Kelp Bed canoPy Area Mappinq and
Indexing All color infrared slides from the survey
were projected onto the base-line maps, and
after aligning common shoreline features from
each media, individual kelp plants and kelp
canopies (see glossary) were hand transferred.
The transfer process specifically involved: 1)
the visual analysis of the extent of kelp
represented on each slide by reference to color
and surface appearance, 2) the identification of
the "usable" portion of the image that was
largely distortion-free (center three-fourths),
3) positioning this "usable" portion of the
projected image in its proper location on the
base-map, with regard to both shore-line
features and kelp from other overlapping
imagery, and 4) the black shading of all visible
kelp, both developed canopies and individual
plants. These black-shaded areas represented the
areal extent of the actual kelp plants composing
the surface canopy, and areas within the
perimeter of the canopy that did not contain
kelp were left un-shaded. When fully rendered
from the survey imagery, each mapped canopy
closely resembled the appearance of the actual
surface canopy when viewed from above. These mapped canopies represented the
quaiitative kelP bed canopy area (see glossary)
occupied within the survey range, and were
presented in Section 4 - "Kelp Bed Canopy Area
Maps: 2744" - October 1999 (24"x36", 11"x17",
and 8.5"x11"). Similar maps from the 1989
inventory were presented in Section 5 - "Kelp
Bed Canopy Area Maps: 27-44" - October 1989
(24"x36", 11"x17", and 8.5"x11") for comparative
purposes. 3) Quantitative Kelp
Canopy Planimeter Areas and Relative Density
Analysis The quantitative analysis of the sanctuary-wide
kelp resource abundance within the MBNMS was
divided into three sections: a) analysis of the
1999 MBNMS sanctuary wide coastal keip resource, by
CDF&G kelp bed number, b) 'standardization" of
the area anaiysis of the 1989 kelp resource
inventory dataset, and 3) comparison of the 1999
kelp resource extent with that measured during the
19&9 inventory. Observed iarge-scale changes in
resource abundance were presented in the "Gata
Summary/Principle Findings" section. Quantitative kelp bed canopy and planimeter
areas (see giossary) were accurately determined
from the maps using computer image processing
techniques. Each map page was scanned fuil scaie
at 100 dots/inch (dpi) using a "Microtek" 9600
XL flat-bed image scanner. Area values were
determined by screen "pixel counting", utilizing
"Global Lab Image" (V3.1) image processing
software (Data Translation). Kelp bed
canopv/planimeter areas and values for the
relative densitv index (see glossary) were
tabulated by CDF&G kelp bed number,
presented in table 4, and plotted in fiqure
2. B) Standardization of the Area AnalYsis of
the 1989 KelP Resource Dataset As previously described, the 1989 original
kelp imagery data were collected under similar
parameters utilized in the current study. In
addition, the same base-maps and mapping
technique were also employed to render the
extent of the surface canopy. The computer area
analysis, though, did not call for a value for
"quantitative canopy area" (the actual numeric
extent of the surface kelp canopy) or "relative
density indeX', and focused instead only on
~planimeter area", since this was all that had
been used in previous surveys. The "qualitative
planimeter area" (see glossary), instead of
being objectively derived by computer image
enhancement, was subjectively derived by
CDF&G personnel by manually estimating the
kelp canopy perimeter, and assuming 1 OG% kelp
coverage within. Although accurate area values
were subsequently obtained for the "quantitative
planimeter area"; this methodology was not
accurately repeatable for comparative purposes
in this study. In response to these limitations, kelp bed
canopy area maps numbers 27-44 from the 1989
state-wide kelp resource inventory were scanned,
as previously described, and subjected to the
same computer area analysis utilized in the
current (1999) inventory. Comparison of the
total kelp bed planimeter area, utilizing
current methodology, with that determined in
1589 yielded a difference of less than 1%
(25.814 sq. mi. (1999) vs. 25.631 sq. mi.
(1989). Comparisons of area values at the
individual "kelp bed" level, though, averaged a
difference of 10% from that previousiy
determined, further emphasizing the subjective
nature of the previous analysis. The standardized values for 1989 kelp bed
canopy/Planimeter areas and the reiative densitY
index within the MBNMS, by CDF&G kelp bed
number, were presented in table 5, and plotted
in fiqure 3. C) comParisons of the 1989 and 1999 MBNMS
Coastal Kelp Resource Kelp bed canopY/Planimeter areas and values
for the relative density index, for both the
1989 and 1999 inventories were presented in
Table 6 and plotted in fi~ure 4 In order to evaluate the significance of
observed changes in resource extent between the
two surveys, a t-test ("paired two sample for
means") was applied to the data sets from tables
6. This test evaluates whether a samples' means
are distinct, and does not assume equal
population variance (Sokal and Rohlf, 1981).
This test was judged appropriate, since there
was a natural pairing of measurements making up
each distinct value for canoPylplanimeter area
and RDI. Each data pair were analyzed at the 95%
confidence level (p = .05), and the results of
the tests were summarized in the "data
summary/principle findings" section All spreadsheet data from tables 1~ are
provided in "Excel 95/97" ("XLS" - Microsoft
Inc.) file format. The data file, MBNMSK99 XLS,
was included on two 3.5" floppy disks, and
presented in each of the data binders in Section
6 - Electronic Data.
A) Kelp canopy Aerial
Photoqraphy
1) Survey Timing, Imaging, and
Logistic Considerations
A) Base-line Map Preparation
A) Analvsis of the 1999 MBNMS
Sanctuarv-wide Coastal Kelp Resource
 |
 |
Home | Introduction | Visitors | Education | Research | Protection | Calendar | Foundation | Search
Credits
For comments or question please refer to the Webmaster
Last modified on: Jan 8,
2000