A COMPARISON OF THE MARINE-ALGAE FROM THE GOLETA SLOUGH AND ADJACENT OPEN COAST OF GOLETA, SANTA-BARBARA, CALIFORNIA WITH THOSE IN THE SOUTHERN GULF OF MAINE

52 Pages·1994·24.3 MB·English

by  A C Mathieson

RHODORA
JOURNAL THE
OF
NEW
ENGLAND
BOTANICAL CLUB
Vol. 96 July 1994 No. 887
RHODORA,
Vol
No. 207-258, 1994
96, 887, pp.
A COMPARISON OF THE MARINE ALGAE FROM THE
AND
GOLETA SLOUGH ADJACENT OPEN COAST OF
GOLETA/SANTA BARBARA, CALIFORNIA WITH
THOSE THE SOUTHERN GULF OF
MAINE'
IN
Arthur Mathieson and Edward Hehre
C.
J.
ABSTRACT
The seaweed floras from the Golela Slough and adjacent coastal sites near Santa
Barbara, California are compared with several coastal and estuarine habitats wdlh-
One
in the southern Gulf of Maine. hundred fifty-two taxa are described from the
Goleta-Santa Barbara area, consisting of 104 Rhodophyta, 22 Phaeophyta and 26
Chlorophyta. Four of these taxa represent modest range extensions within the
Farlowia Lomentaria
state (i.e., conferta, Giffordia hincksiae var. californica, ca-
seae and Prionitis australis, while two others found within the Slough {Capsosiphon
fuhescens and Microspora pachyderma) are significant additions to the marine
flora of the Pacific Coast. The patterns of species richness and composition four
at
contiguous southern California sites showed strong contrasts due to local envi-
ronmental variability, with the highest numbers of taxa {117 taxa or -77%)
occurring at the sand-abraded nearshorc Golcta Point site and the lowest within
the shallow Slough (26 taxa or ~17%). The depauperate flora of this small arid
salt marsh habitat is dominated by ephemeral green algae (16 species) and Sali-
cornia virginica, with ten other seaweeds 7 reds and 3 browns) only occurring
(i.e.,
New
upstream from mouth. By seaweed
just contrast, estuarine floras within
its
much
England usually have higher numbers of red algal taxa, their "open coastal"
much
floras often extend farther inland (—2.0-8.5 miles) and seaweed standing
stocks are usually dominated by fucoid brown algae. The similarity of the Slough's
New
green algal flora to England's estuarine vegetation striking, with most of
is
50% The
the latter sites exhibiting florislic affinities of or more. analogous dis-
tributional and abundance patterns of ephemeral green algae {Cladophora sericea
and Enteromorpha compressd) and horn
the California snail {Cerithidea cahfor-
New
Scientific Contribution from the Hampshire Agricuhural Experiment
'
Number
Station; also issued as contribution 287 from the Jackson Estuarine
Laboratory and the Center for Marine Biology.
207
Rhodora
208 96
[Vol.
nica) suggest several important interactions between seaweeds and snails, plus
and
several other invertebrates birds.
New
Key Words: seaweeds, cstuarine, coastal, Goleta Slough, southern California,
England
INTRODUCTION
Even though the marine flora of CaUfornia has a long history
of investigations (Papenfuss, 1976), there a lack of information
is
about seaweed communities individual and man's
at sites effect
on them (Murray, 1974; Murray and 1989). In southern
Littler,
Dawson some
conducted of
California, (1959a, 1959b, 1965) the
earliest investigations of intertidal seaweeds during 1956-59, pro-
viding a ''semi-quantitative baseline" of floras at 44 stations be-
He
tween Point Conception and the U.S. -Mexican border. con-
cluded that a major reduction of species richness had occurred
some sew^age-impacted within Los Angeles County
since
at sites
and an of
the early 900's, increase selected articulated corallines.
1
Dawson's
After resurveying of southern California be-
15 sites
Dume
Dana Widdowson
tween Point and Point during 1968-70,
He
(1971) found a further reduction in species richness. suggested
that sewage discharge, along with foot and air pollution,
traffic
were important factors causing an abundance of gelidioid turf
and
algae {Gelidium coulteh/G. pusillum) articulated corallines
(Thorn and Widdowson, 1978). Subsequent to the Santa Barbara
oil spill in 1969, several investigators (e.g., Foster et al., 1971;
Nicholson and Cimberg, 1971; Straughn, 1971) documented a
further loss of some species and an increase of others Ulva,
(e.g.,
Corallina and Gelidium) which were capable of uptaking
dis-
amino North
solved acids (Murray, 1974; 1970). In dis-
et
al.,
cussing short-term plant loss immediately after the Foster
spill,
between
noted a strong interaction dispersal,
et al. (loc. cit.) oil
storms and sand fluctuations. Three and one-half years Cim-
later,
berg (1973) re-investigated several intertidal beaches near
et
al.
Santa Barbara and stated that periodic inundations by sand were
more important than rocky epibenthic communities
in altering
oil
(Emerson and
Zedler, 1978; Littler, 1980; Littler et al, 1991;
Nicholson, 1972; Nicholson and Cimberg, 1971; Stewart, 1983;
Thorn and Widdowson, Widdowson,
1978; 1971). In ranking the
com-
of Santa Barbara Nicholson
the
effects oil spill, (loc. cit.)
mented that was only one of several abuses to these coastal
is
Hehre—
Mathieson and
1994] Golela Slough 209
many
which
waters, dated back 1920 summarizing
ol to the In
s.
the effects of chronic long-term pollution near a natural seep
oil
Goleta Coal Devereaux
in Oil or
(i.e., Point), Littler et (1991)
al.
seaweeds
stated that several either failed to recruit or recolonized
very slowly, while Foster and Nicholson and Cimberg
et 9 7
al.
( 1 )
1
(1971) noted diminutive and/or depauperate comparing
In
floras.
the ecology of a sewage polluted on San Clemente
site Island,
Murray and
found pronounced
Littler (1974) changes in species
and
richness reduced spatial heterogeneity versus nearby controls.
Until have been
recently, estuaries the least studied coastal
environments
California Macdonald,
in (Josselyn, 1983; 1977;
Macdonald and
Barbour, and Nord-
1974; Zcdler, 1982b; Zedler
most
by, 1986). In addition, studies of estuarine seaweeds have
emphasized and
productivity ecological evaluations (Rudnicki,
Shellem and
1986; Josselyn, 1982; Zedler, 1977, 1980, 1982a,
1982b), while there have been relatively few detailed assessments
of composition and
species (Josselyn West, 1985; Norris, 1970;
Ripley, 1969; Silva, 1979). Several factors have contributed to
the limited knowledge of estuarine seaweeds: the more
local-
(1)
ized occurrence of estuarine versus rocky and sandy
habitats
(Chapman,
1977; Littler et 1991; Macdonald, 1977; Onuf,
al.,
muddy
1987; Reimold, 1977); the and often eutrophied con-
(2)
ditions within estuaries versus the clean sand and pounding surf
of the open coast (Silva, 1979); the apparent dominance of
(3)
(Mason,
1957); the perceived oc
(4)
cryptic algal flora and; the massive
(5)
southern
(Macdonald
of coastal wetlands in southern California, Zedler
(loc. cit.) states
that there are about thirty wetlands within this geography with a
-5000 em
total area of ha 12.500 acresl She also
f
~25%
what upon
acreage of European
this existed the arrival of
is
man
(Speth 1969). In discussing the functional role of estuarine
Mann
seaweeds,
(1972) states that they provide valuable habitats
myriad
for a of organisms; they also contribute organic carbon
to
and
detrital cycling (Josselyn and Mathieson, 1978, 1980). With
may
increased eutrophication, massive blooms occur within
algal
these sheltered habitats (Bach and Josselyn, 1978; Johnson, 1971;
McComb
Norton and
et al., 1981; Mathieson, 1983; Sawyer,
1965; Sewell, 1982; Silva, 1979; Wilce 1982; Wilkinson,
et
al.,
1980).
t
Rhodora
210 96
[Vol.
—
T
r
ARGUELLO
' PT
GAVIOTA
SANTA BARBARA
PT.
GOLETAPT /BAY SLOUGH
&
CARPENTERIA
PT LAS PITAS
PT.CCNCEPTION
VENTURA
MILES
4
PORT hUENEME
POINT ARGUELLO TO PONT DUWE
34
119** 10 DUME
IZO^IO' PI
Figure The southern California coastline between Point Arguello and Point
1.
Dume, showing the locations of the Goleta Point, Bay and Slough plus
sites,
Naples
Reef.
The
was document
present study open
initiated to the coastal
and
estuarine seaweeds near Goleta and Santa Barbara,
California
We
(Figure have attempted summarize com-
to the species
1).
and
position distributional patterns of marine macrophytes with-
in this arid, Mediterranean geography (Macdonald, 1977; Onuf,
Onuf
and
1987; Zedler, 1988;Zedler, 1982b; Zedler and Nordby,
New
comparing them
with England
1986), thirteen
coastal-es-
tuarine habitats having diverse topographies and hydrographic
conditions.
METHODS AND
MATERIALS
Seasonal and observations of seaweed populations
collections
made
were during 1979 four coastal-estuarine habitats between
at
Goleta and Santa Barbara, Cahfornia (Figure and Appendix).
1
made
Estuarine collections were within the Goleta Slough (Figure
while open coastal samples were obtained at Goleta Point and
2),
Bay
within Goleta near the University of California, Santa Bar-
Campus
bara (UCSB), as well as at Naples Reef, offshore from
A
Santa Barbara synopsis of each general
Point. location,
site's
topography and substrata given in the Appendix. Overall, the
is
most detailed spatial sampling was conducted within the shallow
most comprehensive
Goleta Slough, while the seasonal collections
made
were Goleta Point. Twenty-seven Slough were eval-
at sites
uated during the spring and summer, while monthly collections
made
of 12 months) were along an intertidal-shallow subtidal
(9
Hehre—
Mathieson and Goleta Slough 211
1994]
Figure Twenty-seven study within the Goleta Slough and the adjacent
2. sites
open
coast.
(—10
transect at Goleta Point. Periodic subtidal samples to 30
were made near an experimental farm Goleta Bay
feet) site in
(Wheeler et 1981), while analogous subtidal collections were
al.,
—40
made (—
Naples Reef conspicuous seaweeds
All
at 5 to feet).
1
were collected within the intertidal (on foot) and subtidal zones
SCUBA)
when The
were
(by each both habitats present.
at site
samples were sorted and identified using Abbott and Hollenberg
and primary
(1976), Scagel et al. (1986) Stewart (1991) as refer-
some
ences. Several other synopses were also consulted, including
dealing with North Atlantic seaweeds Bliding, 1963, 1968;
(e.g.,
Dawson,
Collins, 1909, 1912; 1946; Scagel, 1966; Silva, 1979;
Smith, 1969; South and Tittley, 1986; Sparling, 1971, 1977; Tay-
1957; Webber and Wilce, 1971; Wilkinson, 1980). Approx-
lor,
imately 550 herbarium voucher specimens are deposited in the
New
Hodgdon (NHA)
Albion R. Herbarium of the University of
Hampshire document
to the region's flora.
A
common
number
comparison of of
the species in to the
New
Goleta Slough and thirteen England estuarine habitats
is
Mathieson
given, using a variety of published synopses (see et ah,
New
The and England
1993). nature of these California floras
is
+
compared using Cheney's (1977) floristic ratio, (R C)/P:
Rhodora
212
96
[Vol.
# of Rhodophyta and Chlorophyta
species
# of Phaeophyla
species
<
With
this calculation, a value of 3.0 indicates a temperate or
>
''cold-water" flora, while intermediate values and those 6.0
mean
and The
indicate ''mixed'' "warm-w^ater'' respectively.
floras,
New
number
of from Goleta Slough and
taxa/site the thirteen
England was compared.
estuarine habitats also
Monthly and
records of surface water temperatures
salinities
were recorded Goleta Point during while hydrographic
at 1979,
made summer
surveys of the Slough were during the spring and
A
of same hand-held thermometer and
the refractometer
year.
were used for these measurements, having accuracies of 1°C and
0.
Monthly
0.5%o parts per thousand), respectively. records of
(i.e.,
sand levels within the intertidal zone Goleta Point were doc-
at
umented
by drawing metered uniform
out a line to a distance
between two rock outcrops with permanent bench marks (cement
Sand were determined by plumbing down
nails). levels to the
m
^1.0
sand/rock interface at intervals along the transect line
Ah
(Daly and Mathieson, were
1977). elevations corrected to
(MLW)
mean
low water after multiple measurements from these
bench marks. Monthly comparisons of and sand
species richness
were made.
levels
Abundance
patterns of several green algae and the California
horn Cerithidea (Haldcman), were documented
snail, californica
A
from
three shallow pans within the Slough. quadrat frame
(1/
m
m^) was positioned --0.9 and sam-
6 at intervals the contents
1
^40
pled. Individual seaweeds were dried (60°C for hours) and
quantified as g dry weight/m-; snail density was enumerated as
#/m2
HABITAT DESCRIPTION
As
outlined by Ricketts most of the southern
et (1985),
al.
wave
California coastline exposed to moderate action due to
is
—
an offshore archipelago the Channel Islands. Even a strong
so,
may
gradient of water motion (Wheeler ctaL, ranging
exist 1981),
from Naples Reef (most exposed) Goleta Bay and Slough
to Point.
A
(most sheltered). pronounced gradient of rocky substrata occurs
here, with Naples Reef having the most abundant rocky substrata
and The
Goleta Slough the broad sandy beaches the
least. at
Hehre—
Mathieson and Goleta Slough 213
1994]
2.0
5
-
1.5
I
-
1.0
E
-
0.5
-
(3 0,0
LLI
-
-0.5
Q
<
-1.0
25 30
5 5 2
1 1
HORIZONTAL DISTANCE
(m)
Figure Variation of sand Goleta Point between two major rock
3. levels at
outcrops and 10-15 m).
at
(i.e.,
Goleta Point and Bay have scattered rock outcrops and
sites
Monterey which buried
boulders shale/siltstone), are often
(i.e.,
and
extensively scoured (Littler et ah, 1991). Figure 3 illustrates
the variation of sand levels on the Goleta Point transect. Although
sum-
rather sand elevations were usually highest during
irregular,
mer
and lowest winter (February). In organisms
(July) in situ
may
growing in such habitats be removed, scoured or buried by
more mid-summer.
meter of sand during
a or
downstream from
Goleta Point (Figure located a natural
1) is
oil seep at Coal Oil (Devereaux) Point (Littler et al, 1991). In
noted
discussing the effects of the seep, Foster et al. (1971) that
30-60%
of the rock surfaces Goleta Point were covered by
at tar,
causing a conspicuous reduction in abundance and stature of ben-
Although we and
organisms. did not quantify the distribution
thic
we
abundance on concur with
of this "tar'' the intertidal transect,
Foster et al. (loc. cit.) that it must, at the very least, reduce the
availabihty of rocky substrata for benthic organisms.
marsh
Goleta Slough a small, shallow, arid salt habitat located
is
Onuf
-34"25'N and 119°50'W As noted by and
(Figure
at
2).
Zedler the average annual precipitation within this locale
(1988),
< cm
40 (Baldwin, 1974) and the only substantial streamflow
is
occurs just after a major storm. Because of such climatic extremes
and the Slough's shallow topography, evaporation usually exceeds
March
and monthly
precipitation after saturation deficits often
214 Rhodora
96
[Vol.
~
exceed 10 cm. Tidal limits of the Slough extend 1.0-1.2 miles
mouth
inland from near Goleta State Beach Park. Like the
its
Tijuana Estuary San Diego, wetland-dominated
in a habitat,
it is
embayment
with no major and a relatively narrow ocean con-
and Nordby, The midway
nection (Zedler 986). Slough located
is
1
UCSB
between Santa Barbara's Municipal Airport and the cam-
pus. Thus, an urbanized and highly modified estuary (Norris,
it is
1970; Zedler and Nordby, with northeastern perimeter
1986),
its
due
drastically altered to airport expansion, while the construction
of overpasses for gas pipelines and roads) and bike paths has
(i.e.,
changed
topography. In addition, a large part of the Slough
its
is
in the form of channels, which are artificially deepened for flood
and from marsh
control separated the adjacent by dikes (Onuf,
salt
1987). Currently, the west-central part of the Slough dominated
is
by major which ^0.52
three tidal channels, bifurcate miles up-
stream from mouth near the Clarence Ward Memorial Boule-
its
vard overpass. Further upstream (--0.94 miles inland), the source
of these channels evident Glen Annie Creek and an
tidal
is (i.e.,
unnamed
channel running Aero Camino
Road).
parallel to In the
east-central portion of the Slough, three creeks converge between
— SW
0.42-0.51 miles inland, with two originating from S and
flowing flood channels San Pedro and San Jose Creeks,
(i.e., re-
spectively) and one arising from a tributary due east near Atas-
Twenty-four were
cadero. study established along the west
sites
central tidal channels, two near the Slough's mouth and one
at
dam
the tidal near Atascadero (Figure 2 and the Appendix).
Most
of the Goleta Slough consists of marshes, shallow
salt
pans and a series of channels (Appendix). Scattered boulders and
artificial structures bridge abutments, pilings, broken pieces
(i.e.,
of asphalt, are most abundant near the Slough's mouth and
etc.)
occur sporadically upstream. Sand periodically blocks the mouth,
summer
restricting tidal exchange and contributing to enhanced
salinities (Figure Macdonald, 1977; Onuf, 1987; Onuf and
4;
As Onuf
Zedler, 1988; Zedler, 1982b). outlined by and Zedler
dominant marsh
(loc. Salicornia virginica L. the plant
cit.), is salt
within this tidally restricted habitat (94% frequency of occur-
amounts
rence), with only patchy (1-2%) of Cotula coronopifolia
Frankenia gmndifolia Chamiso Schlechtendal and Lolium
L.,
et
perenne
L. Zedler (1982b) hsts eleven additional flowering plants
from
the Slough: Atriplex watsonii A. Nelson, Cressa
truxillensis,
H. Engelmann,
B. K., Ciiscuta salina Distichlis spicata (L.) Greene,
Hehre—
Mathieson and
Goleta Slough 215
1994]
35-1
A
o
f^- r^
t ^
30 - 1
LU
I t
\
y i
1
I
-^
¥
<
t
25 -
i
tr
i
LU
I
4
20-
UJ
15
10
80n
o
o
<
0.0 0.2 0.4 0.6 0.8 1.0 1.2
DISTANCE INLAND
(MILES)
Figure Surface water hydrographic conditions temperature and
4. salinity)
(i.e.,
at Goleta Point and adjacent Slough during March and June of 1979.
Jaumea
carnosa (Lessing) Gray, Lasthenia glabmta Lindley,
Li-
monium
Monanthochloe
californicum Heller, Engel-
littoralis
mann,
Salicornia subterminalis Parish, Suaeda Wat-
californica
son and Triglochin concinnum Davy. Although we primarily
studied the macroalgal communities within the Slough, a variety
of Vaucheria and microscopic mats
algal blue -green algae
(i.e.,
muddy
and
diatoms) occur on
also surfaces (Onuf, 1987; Zedler,
As Onuf
1980, 1982a, 1982b). outlined by the overaH
(loc.
cit.),
coverage of seaweeds relatively small versus that of emergent
is
vascular Seaweeds, grow
plants. therefore, attached widely
to scat-
sohd
tered substrata, as entangled masses on the banks of
tidal
channels and epiphytes upon marsh The dom-
as vegetation.
salt
inant macro-invertebrate within Slough
the Cerithidea caUfor-
is
6
Rhodora
2 [Vol. 96
1
horn 1982b; Zedlcr
the California snail (Onuf, 1987; Zedler,
nica,
andNordby,
1986).
and
Figure 4 illustrates surface water temperatures salinities at
March
Temperat
from~14.0°-24.0°C
March Goleta Point
during to -- 17.0°-35°C in June. Salinities at
were constant 30-3 while those within the Slough
relatively at l%o,
~
-27
from %o March 12-68%o June. During
varied to in to in
< months
March, twelve Slough had sahnitics of 2%o. Three
sites
and while
10 13%o,
(J
A
maximum
>
had
seven 28%o.
salinities
sites
corded one shallow pan with abundant green algae and horn
in
ABUNDANCE
PATTERNS).
snails (see
AND NEW RECORDS
COMPOSITION DISTRIBUTIONAL
SPECIES
One hundred seaweed taxa were recorded from the
fifty-two
Rhodophyceae, 22 Phaeophyceae
four study including 103
sites,
The numbers
and 26 Chlorophyceac (Table highest of taxa or
1).
were recorded Goleta
percent contribution to species richness at
-77%)
Point (117 taxa or and the lowest within the Slough (26
-17%). Most taxa from Goleta Point occurred on the
taxa or
shallow transect 94 taxa or -62%), while the remainder were
(i.e.,
UCSB
campus
collected immediately offshore from the 23
(i.e.,
-
Naples Reef and
taxa or 5%). Floristic patterns at at the off-
1
shore Goleta Bay were somewhat intermediate, with 52 taxa
site
(-34%) occurring at the former and 39 (-26%) at the latter.
The numbers (%) of red, brown and green algal taxa/site were
Green were maximal Goleta
highly variable (Table algae at
1).
numbers
Point and within the Slough while the lowest
(19) (16),
Brown
Bay and Naples Reef
occurred the offshore Goleta
at (2)
(1 ).
and and
and red algae were highest Goleta Point (17 81 taxa)
at
lowest within the Slough and 7 taxa). Green algae dominated
(3
and
Slough (-62%), were intermediate Goleta Point (16%)
the at
Naples Reef and Goleta Bay
lowest the offshore (2%) sites (5%).
at
The percentage contribution of brown algae was minimal within
Slough with depauperate (-12%), while ranged
the flora
its it
-15-33% Red
from the Goleta Point and Bay algae
at sites.
Go-
dominated Naples Reef (-85%), were intermediate the
at
at