Expansion of the Asiatic green alga Codium fragile subsp tomentosoides in the Gulf of Maine

53 Pages·2003·21.3 MB·English

by  A C Mathieson

RHODORA,
Vol. 105, No. 921, pp. 1-53, 2003
EXPANSION OF THE GREEN ALGA CODIUM
ASIATIC
TOMENTOSOIDES THE
FRAGILE
SUBSP. IN
GULF OF MAINE
Arthur Mathieson
C.
Department of Plant Biology and Jackson Estiiarine Laboratory,
NH
New
University of Hampshire, Durham, 03824
[email protected]
e-mail:
Dawes
Clinton
J.
PL
Department of Biology, University of South Florida, Tampa, 33620
Larry
Harris
G.
NH
New
Department of Zoology, University of Hampshire, Durham, 03824
Edward
Hehre
J.
Department of Plant Biology and Jackson Estuarine Laboratory,
NH
New
University of Hampshire, Durham, 03824
ABSTRACT. The invasive Asiatic green alga Codium fragile subsp. tomen-
tosoides, which was introduced to the northwestern Atlantic in eastern Long
New
Island Sound, York during 1957, has recently colonized several parts of
the Gulf of Maine via two invasion sites: (1) mid-coastal Maine at Boothbay
Harbor after transplantation of Long Island oysters (1964); and (2) southern
Cape
Massachusetts as a result of the expansion of attached plants from the
Cod Canal (1969) into nearby Cape Cod Bay (1972). Because of warm-
its
New
England expanded more
water southern populations
affinities, initially
rapidl) than northern ones, becoming paiticularly invasive in shallow subtidal
By
habitats. contrast, the Boothbay Harbor populations were rather ''quies-
cent," long-lived, and circumscribed until the early 1970s. After a buildup
of significant biomass, extensive fragmentation and drifting occurred via
strong south-flowing currents; thereafter. Codiiim colonized mid-coastal
New
Maine, Hampshire, and northern Massachusetts. Currently, the Casco
Bay area just south of Boothbay Harbor has the highest number of invasion
particularly offshore islands. Attached populations are limited to a
sites, at
few contiguous sites just north of Boothbay Harbor, with only drift specimens
occurring in "Downcast** Maine. Recent introductions have also been re-
corded in the Canadian Maritime Provinces, both within the Atlantic (1989)
and Gulf of Lawrence (1996) shorelines. Thus, the species' expansion
the St.
nonhwestem
Atlantic has involved multiple introductions, different
in the
vectors (shellfish and vessels), dispersal by major south-flowing currents, and
differential viability/abundance of in situ populations due to varying hydro-
graphic and exposure conditions. In comparing a series of permanent study
New
southern Maine and Hampshire during 1982 2001, Codiiim
sites in to
increased from one to 26 sites during 19 years, with the most evident expan-
1
BOTANICAL
MISSOURI
APR
t 8 2003
GARDEN LIBRARY
Rhodora
2
[Vol. 105
A
sion between 1996-1998. comparison of several demographic features
Codium
(length, weight, density, biomass, and percent occurrence) for six
New
populations ranging from mid-coastal Maine to Hampshire showed that
outer estuarine and nearshore open coastal plants were smaller and had more
limited densities and biomass than those found at warmer offshore insular
New
Hampshire. Codium now dominant canopy
sites like Star Island, the
is
New
species in some southern Maine and Hampshire locations, extending to
m
"-8 below mean low water; occurs both disturbed former
in sites (e.g.,
it
urchin barrens) and established kelp beds sheltered and exposed locations.
at
The Asiatic red alga Neosiphonia (= Polysiphonia) harveyi, which the
is
dominant epiphyte on Codtum, is also exhibiting a rapid expansion in this
same geography. Drifting populations of Codium may be a good vector for
introduction, as well as for several other epiphytes. Another aspect of the
its
invasion of Codium into the Gulf of Maine the spread of the introduced
is
common
bryozoan Memhranipora membranacea, which on kelps but ap-
is
pears to be exhibiting enhanced survival on Codium because of perennial
its
growth and of
pattern lack epibiontic sloughing.
Key
Words: green alga, Chlorophyta, Codium fragile subsp. tomcntosoides,
Asiatic, introduced, nonindigenous, invasive. Gulf of Maine,
dispersal, distribution, ecology, epiphytes
Introduced species are a major problem throughout world's
the
oceans, causing altered natural communities and eco-
significant
nomic
(Boudouresque
losses et 1994; Carlton 1979, 1996,
al.
De
Chapman
2000; Clerk 2002; Jousson
et al. et al. in press; et
2000; Karlsson and Loo 1999; Lein 1999; Maggs and Stegena
al.
Meinesz Meinesz
1999; 1999; 1993; Pederson 2000; Piazzi
et
al.
Ramus
and
Cinelli 2000; 1971; Reise 1999; Rueness and Ruenes<
2000; Stiger and Payri 1999; Thresher 2000). In the northwestern
Atlantic ten nonindigenous seaweeds are known Broom
(cf. et al.
Humm
Cox
2002; Coll and 1977; 1979; Kjellman 1897; Mclvor
et al. 2000, 2001; Sears 2002; Taylor 1962; Villalard-Bohnsack
2002; Vitousek Codium
et al. 1996): the invasive green alga frag-
R
(Suringar) Har. subsp. tomentosoides (Goor)
ile C. Silva (here-
after Codium); the brown algae Colpomenia peregrina Sauv. and
Fucus
serratus L.; and the red algae Antithamnion pectinatum
(Mont.) Brauner, Bonncmaisonia
hamifera
Har. [including the
Agardh)
"'Trailliella intricata"' Batters Furcellaria
(J. stage],
lumhricalis (Huds.) V. Lamour., Gniteloupia tunitum Yamada
J.
[= G. doryphora (Mont.) M. Howe; Gavio and
Fredericq
cf.
=
2002], Lomerttaria clavellosa (Turner) Gaillon, Neosiphonia
(
&
Polysiphonia) harveyi (Bailey) Kim, Choi, Guiry G. W. Saun-
—
Mathieson Expansion of Codiuni
2003] et fnii^ile 3
al.
ders, and Porphyra siiborbiculata Kjellm. (= P. carolinensis Coll
&
Broom
Cox; Bonnenuiisonia Cod-
2002). haniifera,
J. cf. et al,
ium, N. han'eyi, and P. suborbicidata are Asiatic, while the rest
unknown
from
are Europe, the Pacific, or locations (Blackler
1964; Coleman 1996; Dale 1982; Foertch et 1991; Goft et
al. al.
1992; Harvey 1853; Kjellman 1897; Lewis and Taylor 1928,
M
Wil
1964). The earliest documented introductions within this geog-
raphy date back to the early to late 1800s and include F, serratiis
Hay
from the Canadian Maritime Provinces (Dale 1982; and
Mackay Novaczek Robinson
1887; 2001; 1903), F. lumbriccdis
from Newfoundland (Harvey 1853; Novaczek 2001), and N.
han^eyi from Connecticut (Harvey 1853; Mclvor 2000,
et
al.
was
most
2001); recently, the foliose red alga G. tunituru re-
Rhode
corded from (Marston and Villalard-Bohnsack
Island
Of
2000; Villalard-Bohnsack and Harlin 1997). these ten sea-
weeds, Bonuemaisonia and broadly Cod-
persistent distributed;
is
C
and haneyi expanding; per-
Grateloiipia, N, are rapidly
iuffh
few and
egrina restricted to a locations; the others exhibit lim-
is
Broom
expansions (Bird and Edelstein 1978; Blackler 1964;
ited
2002; Carlton and Scanlon 1985; Marston and Villalard-
et
al.
Bohnsack 2000; Mclvor 2000, 2001; Sears 2002; South and
et al.
The
Tittley 1986; Villalard-Bohnsack 2002). Asiatic red alga Por-
Ueda
phyra yezoensis nori) has recently been cultivated
(i.e.,
New
within ''Downcast'' Maine and Brunswick, Canada but has
shown no signs of escaping or becoming invasive (Watson et
al.
1998, 2000).
Trowbridge
(1995, 1996, 1998) has described the introduction
show
and spread of several seaweeds throughout the world that
varying After escaping from a coastal aquarium, the
patterns.
tropical/subtropical green alga Caiderpo taxifolia (Vahl) C.
Agardh become major Mediterranean (Bou-
has a pest within the
douresque 1994; Meinesz 1999; Meinesz 1993; Raloff
et et al.
al.
Wiedenmann
1998; et 2001), as well as being recently found
al.
seaweed
California (Jousson 2000). Vectors for other
in et
al.
introductions include: Lessepsian migrations into the Mediterra-
nean via the Suez Canal, shellfish/algal transplants, mariculture
introductions, and accidental transfers via ballast water, anchors,
and packaging
platforms,
fishing nets, ships' hulls, oil shellfish
De Hay
(Aleem 1948, 1992; Carlton 1987; Clerk et 2002;
al.
Rhodora
4
[Vol. 105
Maggs Hommersand Modena
Loosanoff and
1990; 1975; 1993;
Moss
2000; 1981; Piazzi 1997; Russell 1982,
et al. et al, et al.
The brown
1983; Scagel 1956; Verlaque 1994). temperate algae
Laminaria japonica Kjellm., Sargassum muticum (Yendo) Fen-
sholt, and Undaria pinnatifida (Harv.) Suringar have spread dra-
between
matically during the century, extending different
last
ocean basins and hemispheres (Cecere 2000; Critchley
et al. et
Hay Hay
ah 1983, 1990; Floc^h 1991; 1990; and Villouta
et al.
Loo
1993; Karlsson and 1999; Rueness 1989; Sanderson 1990;
Scagel 1956; Staehr 2000; Trowbridge 1995, 1996). Their
et al.
dispersal attributable in large part to shipping and oyster im-
is
Codium
Sargassum,
portation below), has be-
activities. like (see
come
an ecological and economic disrupting oyster beds,
pest,
By
boat harbors, etc. (Rueness 1989). contrast at least 95 intro-
duced seaweeds more (Farnham
are localized 1980; Verlaque
some
with producing and
1994), naturalized viable populations
and
(Russell 1983, 1992; Russell Balazs
1994).
The
Codium
invasive Asiatic green alga fragile subsp. tomen-
commonly
weed"
tosoides is called "sputnik or '*oyster thief"
because of its rapid growth, as well as its ability to attach, uplift,
and transport shellfish (Hanisak 1980; Novaczek 2001). The
first
Codium
record of foreign travel by dates back --1900 Hol-
to in
where was
presumably
land, introduced with
shellfish (Silva
it
Goor
1955, 1957; van 1923). Thereafter expanded rapidly
in
it
Norway
Europe, extending from Spain western edge
to into the
of the Mediterranean (Jones 1974; Luning 1990; Meslin 1964;
Parriaud 1957; Silva 1955; Trowbridge and Todd
1999, 2001).
Codium was
recorded 1957 from
first in the northwestern Atlantic
Long
in eastern Island Sound (Bouck and Morgan Other
1957).
New
recent introductions have occurred
in Australia, Zealand, the
central Pacific Islands, Japan, Alaska to Pacific Mexico, and west-
ern South America (Luning
1990; Nelson 1999; Trowbridge
1995, 1996, 1998). Carlton and Scanlon (1985) considered three
possible vectors Codium
for the transoceanic dispersal of the
to
northwestern
Atlantic: (1) fouling of the oyster Ostrea edulis
flat
from
Europe;
L. (2) fouling of the Pacific or Japanese oyster
Crassostrea gigas (Thunb.) from Washington and Colum-
British
and
bia; fouling of from They
(3) ships' hulls Europe. concluded
was
most
that it likely transported as a fouling organism on ships'
hulls (cf. Loosanoff 1975; Malinowski was
1974), as there daily
New
shipping between Europe and York
during mid-1950s
the
—
2003] Mathieson et al. Expansion of Codiiim fragile 5
just prior to the discovery of Codiuni (Bouck and Morgan 1957).
Dromgoole Codium
(1975, 1979) stated that has several features
that would preadapt for ship-borne dispersal: settlement on
it (1)
floating structures imperfectly coated with antifouUng paint;
(2)
attachment to diverse substrata with minimal reUef; and (3) re-
generation from residua] holdfasts subjected to reduced shear
stress during ship-borne dispersal (Hanisak 1980). Carlton and
would
Scanlon (1985) suggested a fourth factor that be critically
namely which
important, the species' physiological plasticity,
would permit through broad and changing temperature
to exist
it
and salinity regimes. They suggested that the species' localized
was caused by of
dispersal largely currents, transport fishery
and mechanisms. For example,
products, other natural the
initial
establishment of Codium on the south shore of Massachusetts
(MA) during 1961 and Boothbay Harbor, Maine (ME) 1964
at in
probably occurred after transfer of juvenile/microscopic plants
"green bumps'') on oysters (Coffin and Stickney 1966; Gal-
(i.e.,
Wood
Malinowski Other
stoff 1962a,b; 1974; 1962). possibilities
on
include transport of plants boat propellers, the cutting off of
Codium from and them back
shellfish (oysters) tossing into
thalli
the water, entrainment on commercial drag nets, and dispersal via
packing worms,
material for lobsters, bait etc. (Carlton 1979;
Dawson
and Foster 1982; Garbary 1997; Hillson 1976;
et
al.
human
Novaczek Aside from
2001; Orris 1980). causes, natural
may
mechanisms
dispersal include motile reproductive veg-
cells,
etative fragments, and floatation of whole plants via currents.
Codium
populations within the northwestern Atlantic, like
now
those in Europe, have expanded rapidly and extend from the
New
Nova
Canadian Maritime Provinces Brunswick,
Scotia,
(i.e.,
and Prince Edward Island) to North Carolina (Bird et 1993;
al.
Chapman Chapman
Bleakney Cole-
1996; 1999; et in press;
al.
man
and Mathieson 1974; Davis 1971; Garbary and Jess 2000;
Meimer
Garbary 1997; Hubbard and Garbary 2001, 2002;
et al.
w
1972; Scheibling 2001; Schneider and Searles 1991; Schumacher
and Fiore 1963; Searles 1984; Sisson 1968; Taylor 1967;
et
al.
Wassman Ramus many
and 1973a,b). Currently dominates sub-
it
New
Canadian Maritime Provinces and Eng-
habitats the
tidal in
land, replacing Laminaria as the major taxon, and often impacting
communities (Berman 1992; Carlton and Scanlon
shellfish et
al.
1985; Hanisak 1980; Harris and Mathieson 2000; Harris and Tyr-
Ramus
2001; Hulbert 1980; Luning 1990; Martin 1988;
et
rell al.
Rhodora
6
[Vol. 105
Van
Tacy
1971; Scheibling 2001; 1977; Patten 1992). In
et
al.
New
England and Canadian Maritime Provinces
contrast to the
where Codium (Coleman Garbary
often a subtidal pest 1996;
is
al 1997; Hubbard and Garbary 2001, 2002; Prince 1987),
et
it
New
abundant Europe and Zealand, often producing
is less in
Kuhlenkamp
and
small populations (Bartsch
distinct intertidal
Chapman Chapman
Freeman and Smith
2000; 1999; 2001;
et
al.
New
Codium more
2000). In England, abundant south than
is
MA,
north of Cape Cod, presumably because of warm-tem-
its
perate and the occurrence of a major phytogeographic
affinities
Cod
boundary Cape (Carlton and Scanlon 1985; Fralick and
at
Mathieson 1973; Hanisak 1980; Hutchins 1947; Luning 1990;
Ramus
Mathieson The
et al. 1991; 1971). goal of this paper is to
review the recent rapid spread of Codium within the Gulf of
Maine (Figure which extends from mouth of Bay of
the the
1),
MA. We
Fundy southward Cape Cod, combination
to will use a
of and
historical recent studies, including extensive collections
and
quantitative sampling, to describe the plant's current status.
Among
Davis have emphasized
others, et (2001) the impor-
al.
tance of comparing historical and present-day collections un-
in
derstanding the temporal occurrences of marine
biota.
MATERIALS AND METHODS
M
to
summarized based upon
ten previous studies conducted
floristic
?001 (Mathieson 1979; Mathieson
e1
Mathieson and Math
Fralick 1972:
Math
(Math
sonal collections of conspicuous seaweeds were
all taken within
SCUBA)
the intertidal (on foot) and subtidal zones (by 922
at
New A
within Maine, Hampshire (NH)
sites and Massachusetts.
variety of taxonomic references were employed
for the
identifi-
of
cation various epiphyte populations Mathieson
1998,
(cf. et
al.
Nomenclature
2001). primarily follows South and
Tittley (1986)
and
Sears except some
(2002), for recent changes noted by
Broom
Choi
et al. (2002), et (2001), Gavio and Frcdericq
al.
Maggs
and
(2002), et (2002). Voucher specimens of Cod-
al.
all
ium populations were prepared and
deposited Albion
the R.
in
—
Mathieson Expansion of Codiiim
2003] et fragile 7
al,
""I
T
71
'^
U. S. A.
MAINE
\
\
\
\
V
\
\
PORTLAND
GULF OF MAINE
N.H.
BOSTON
km
20
MASS.
t I
OCEAN
ATLANTIC
CONN.
\
1
Figuie The northwestern Atlantic coastline from Nova Scotia, Canada
1.
to Cape Cod, including the northern invasion site for Codium at Boothbay
ME ME
Harbor, C'A"), a study site at Jaquish Island, C'B"'), it's southern
invasion near the mouth of the Cape Cod Canal and Cape Cod Bay
site
("C"), plus twelve major habilals within the Gulf of Maine: #1 *'Down East"
ME; ME; ME;
#2 Penobscot Bay, #3 the "Indented Coastline" of #4 Casco
ME
NH/ME
ME;
Bay, #5 the southern coastline: #6 the Isles of Shoals; #7
NH NH/ME
the nearshore open coast; #8 the Great Bay Estuarine System;
NH
#9 the Hampton-Seabrook Estuarine System; #10 the "North Shore" of
MA, MA; MA;
or Salisbury to Gloucester, #1 Salem to Sagamore, #12 the
1
MA.
Cape Cod peninsula, or Sandwich to Provincetown, Abbreviations:
MASS. New N.H New
Massachusetts; N.B. Brunswick, Canada;
=
Nova
Hampshire; N.S. Scotia, Canada.
Rhodora
8 [Vol. 105
New
Hodgdon Hampshire
Herbarium (nha) of the University of
(UNH).
68% --25%
Of 922 were Maine,
the investigated, in
total sites
—7%
New
Hampshire, and Massachusetts. The presence and
in
in
abundance (% occurrence) of epiphytic populations, plus
relative
were enumerated based upon subsam-
host populations, a
their
pling of 150 herbarium voucher specimens (Appendix) from
"Dow-
Maine
twelve contiguous Gulf of habitats (Figure
1): (1)
ME, Mount
ncast" extending from Desert Island eastward to the
Canadian Penobscot Bay (ME), em-
border; the largest
state's
(2)
bayment, extending from mouth of Penobscot River
the the at
(ME)
Searsport to George; the "Indented Coastline" that
St. (3)
extends from George Brunswick and of of
to consists a series
St.
eroded peninsulas and drainage Casco Bay (ME)
river areas;
(4)
embayment
near Portland, the state's second largest that extends
ME
from Phippsburg Cape
to Elizabeth; the southern coastline
(5)
NH
from Cape
Elizabeth to Kittery near the border; of
Isles
(6)
ME
Shoals, an archipelago of nine offshore islands within and
NH
NH/ME
NH;
open Bay
the nearshore coast; the Great
(7) (8)
NH
Hampton
Estuarine System; Seabrook
the Estuarine Sys-
(9)
tem; (10) the North Shore of Massachusetts, extending from Sal-
MA
isbury to Gloucester; (11) the shoreline extending from Sa-
lem Sagamore; Cape Cod
to (12) the northern shoreline of the
peninsula extending from Sandwich Provincetown (MA).
to
ME NH
The temporal invasion by Codium of the southern and
ME
NH
coastline between Bald Head York, and Seabrook,
Cliff,
(Figure 2) is summarized based upon a subset of 276 of the 922
NH/ME
The
total sites. locations include nine offshore islands at
the Isles of Shoals (Mathieson and Hehre 1986; Mathieson and
NH/ME
Penniman
1986a), 17 nearshore open coastal locations
ME
(Mathieson and Hehre 1986; Mathieson 20
2001),
et sites
al.
ME
York
within the River Estuary (Mathieson 44
et 1993),
al,
within Brave Boat Harbor (Mathieson NH/
sites 2001), 137
et
al.
ME
Bay
sites within the Great Estuarine System (Mathieson and
Mathie
Hampton-
tions within the Seabrook Estuarine System (Mathieson
and
Fralick
1972).
Detailed ecological studies have been conducted by
L. Harris
NH
and
students at Star Island, Isles of Shoals (Figure since
2)
1974 and
at five other Shoals sites since 1992 (Berman ak
et
1992; Harris et al. 1994, 1996; Harris and Chester 1996; Harris
.
—
Mathieson Expansion Codium
2003] et of fragile 9
al.
BALD HEAD
CLIFF
\
MAINE
1
1
OF SHOALS
ISLES
DUCK
F
-
43°00
43^05-
SEA POINT
APPLEDORE
MAINE
GREAT BAY
SMUTTYNOSE
ESTUARIT^ SYSTEM
—
MALAGA
\
NH GOSPORT
IIBR.
\
ME
CEDAR
N. H. \ *'".
LUNGING
SEAVEY
^^.
42'*58' -1
OF SHOAI^
ISLF^ WIHTE
70°36'
70'*38-
HAMPTON-SEABROOK
ESTUARINE SYSTEM J 1 _J
42^55'
10 Ion
ATLANTIC OCEAN
70'55' 70''45'
_L_
I
Figure Locations of attached Codium populations on the southern
2.
New
Maine and Hampshire coastlines during 1983 and 2001; the enlarged
area on the right shows the Isles of Shoals, an archipelago of nine interstate
X =
islands. Symbols: initial occurrence in 1983, as well as during 2001;
=
Codium
black circles occurrences in 2001. Five of the six study sites for
populations are also shown with arrows Cape Neddick, Brave Boat
(lines):
Harbor, and Seapoint, ME, plus South Mill Pond and Star Island, NH. The
shown
location of the Jaquish Island study site is in Figure
1
and Tyrrell 2001; Hulbert 1980; Martin ah 1988; Tacy
et et al.
Witman Witman
These
1977; 1984, 1985, 1987; 1982).
et
al.
studies have provided a general understanding of the changing
patterns of diverse benthic organisms, including several native
seaweeds (Agarum clathratum Dumort., Chondrus crispus
Stackh., Laminaria spp., and Ptilora serrata Kiitz.) and the green
sea urchin Strongylocentrotus droebachiensis (Muller), plus the
Codium and
invasive, introduced green alga the non-native bryo-
Membranipora membranacea Upper
zoan horizontal rocky
(L.).
were Shoals which have
substrata studied at all six sites, histor-
ically either been dominated by large algal canopies (e.g.. Lean-
Rhodora
10 [Vol. 105
destructively grazed by sea urchins, they have
inaria spp.)
or, if
consisted of barrens dominated by crustose coralline algae (Hul-
bert 1980; Martin et 1988; Ojeda and Dearborn 1989; Sebens
al.
Witman Witman
1985; 1984, 1985, 1987; et 1982). Patterns
al.
of canopy, algal distribution, and relative abundance of different
NH &
taxa at five of these six Shoals sites White Island #1
(i.e.,
&
Lunging #4
2, Island #3, Star Island 5; cf. Harris et al. 1994,
A V
compared. Nikonos underwater camera,
1998) are outfitted
mm mm
with a flash, 15 lens, and 35 Ektachrome slide film, was
used document changes abundance and community
to in relative
^ m
—
structure from + 3.0 to 12 relative to mean low water
(MLW). made
Counts of canopy were by
species projecting these
pictures on a screen and documenting relative abundance based
upon 30 photographs per Harris and Malhieson 2000).
site (cf.
Data for Codium and the brown alga Desmarestia aciileata (L.)
V. Lamour. are probably an underestimate since neither small
J.
By
nor individual plants could be distinguished. contrast, the sin-
brown
gle blades of the algae A, clathratum and Laminaria spp.
more
canopy
are accurately represented. Subtidal populations of
C. fragile subsp. tomentosoides, A. clathratum, and saccharina
L.
-
(-4
at Star Island were sampled to 15 m) just prior to the spring
recruitment of bryozoan M. membramicea
the (June 2000)
in or-
der to assess patterns of host specificity.
A
series of permanent transect studies have been conducted
by
annually students at the Shoals Marine Laboratory, with these
documenting
percent coverage of the dominant organ-
intertidal
NH
isms on from 1965-1972
Star Island, Kingsbury 1976)
(cf.
ME
and on Appledore from 1973 Ten
Island, to the present. years
of intertidal transect data on Appledore (Figure were evaluated
2)
confirm Codium
to the establishment of during 1986-1995,
initial
with the data being supplied by present (Dr. Jim Morin, Director)
and former Shoals Marine Laboratory personnel Sarah Co-
(Drs.
hen and Michael
Lesser), Twenty-eight
transects are located
around
the perimeter of Appledore
Island, with these ranging
from exposed
fully to very sheltered locations. Four sheltered
Codium
transects with populations were compared,
with
their lo-
cations (directions) relative to magnetic north being as follows:
(W
T2
shore 250° and Babb's T5 (W
at in Cove), shore 242°),
at
T24 (SE T28 (SW
shore and
at 159°), shore 230°). Data from
at
earlier floristic surveys of the Shoals (Mathieson and Hehre
1986;
Mathieson and Penniman
1986a) also served as a baseline to