J. Exp. Mar. Biol. Ecol., 1986, Vol. 100, pp. 181-208
Elsevier
181
JEM 724
REGULATION
KELPFISH,
OF COLOR MORPHIC PATTERNS
HETEROSTICHUS
ROSTRATUS
ENVIRONMENTAL
IN THE GIANT
Girard: GENETIC VERSUS
FACTORS
CAROL A. STEPIEN~
Department
of Biological Sciences,
University of Southern Cal~omia, Los Angeles. CA 90089. U.S.A.
(Received 22 October, 1985; revision received 1 April 1986; accepted 25 April 1986)
Abstract: Color choice experiments tested preferences of red, green, and brown color morphs of giant
kelp&h, Heterostichus rostratus Girard, for matching versus non-matching colored backgrounds. Kelptish
were determined to prefer matching colors, these results being most pronounced with live plant backgrounds
and progressively less significant with backgrounds of artificial plants and flat plastic panels, respectively.
Adult kelpfish demonstrated a stronger preference for matching back~ounds than did juveniIes.
Kelpfish larvae whose parents colors were known were reared on red, green, or brown colored
backgrounds. They developed brown or green juvenile color morphic patterns, apparently independently
of parent color. These rearing experiments indicated that development of juvenile color is determined by
plant background.
Long-term color change abilities of juvenile and adult kelplish color morphs on colored habitats were
tested in laboratory and in situ experiments. It was found that juveniles readily changed on both artificial
and live plant backgrounds from green to brown, and vice versa. Changes in color of adults were less
pronounced and slower, particularly in laboratory experiments, and largely con&red to females. In situ
experiments yielded the greatest ma~itudes of color change, some adult females changing between red,
brown and green. Male and juvenile kelptish were incapable of becoming red, corresponding to color morph
frequency collection data. Adult males also apparently lost the capability to change to true green. These
differences indicate that color change ability and assumption ofred color may be governed by sex hormones.
Key words: color; color pattern; kelptish; Clinidae; Blennioidei; Heterostichus rostratus; sexual dimorphism;
habitat partitioning
The giant kelpfish, Heterostichus rostratus Girard (family Chnidae, suborder
Blennioidei), is common from Point Conception, California to central Baja California,
Mexico in kelp forests and surrounding subtidal plant habitats. Heterostichus occurs in
three sexually dimorphic color morphs; red, green, and brown (Stepien, 1985, 1986a).
Juvenile kelpfish are found in two colors, green and brown, and almost always match
their plant habitats, whether green surfgrass Phyl~o~padixtorreyi Watson or brown algae
(giant kelp ~acrocy~tis pyrifera Agardh and grapeweed Sargassum muticum Yendo).
Adult female kelpfish occur in all three morphs: red, green, and brown. Adult male
’ Present address: Department of Ichthyology, Marine Biology Div. A-002, Scripps Institution of
Oceanography, University of California at San Diego, La Jolla, CA 92092, U.S.A.
0022-0981/86/$03.50 0 1986 Elsevier Science Publishers B.V. (Biomedical Division)
182
CAROL A. STEPIEN
kelpfish, however, are almost exclusively brown morphs, and rarely, olive brown-green.
Brown males are usually distin~shable
from brown females by their melanophore
patterns. Adults are located in matching colors of plant habitats, male and female
habitats differing significantly in depth and species of plants (Stepien, 1985, 1986a).
This paper presents the results of experiments testing whether kelptish color morphs
are regulated by genetic inheritance and/or environmental factors. The following
experiments were conducted: (1) color choice experiments, (2) experiments testing the
ability of laborato~-ream
larvae to assume juvenile color morphs, and (3) expe~ments
testing the ability of juvenile and adult color morphs to change color with background.
Wilkie (1966) and Burgess (1976, 1978) similarly tested the ability of the pholid fishes
(gunnels) Apodichthysflavidus and Xererpesfucorum respectively, to change color with
background. Like Heterostichus, these two species belong to the infraorder Blennioidei
(Nelson, 1984) and were described by Wilkie and Burgess as exhibiting similar red,
green, and brown color morphic patterns. Both Wilkie (1966) and Burgess (1976, 1978)
tested the ability of these species to change color on artificially colored backgrounds,
Wilkie using painted backgrounds and colored lights, Burgess testing gravel
backgrounds. Their results indicated that, although some fading and slight color
changes involving loss and acquisition of pigments occurred (morphological changes),
the fishes did not change between color morphs over a period of several weeks. Wilkie
(1966) and Crozier & Wilkie (1966) additionally found that red, green, and brown
color morphs of Apodichthys contained the same pigments as those of Heterostichus
(Wilkie & Stepien, in Stepien, 1985).
Wilkie (1966) and Burgess (1976, 1978) also found that the large majority of pholid
color morphs matched their plant habitats in color, similar to kelpfish (Stepien, 1985,
1986a). Both Burgess (1976, 1978) and Wilkie (1966) determined that the color morphs
preferred matching over non-matching backgrounds in laboratory choice experiments.
Wilkie (1966) additionally reared Apodichthys larvae of known parents and found that
they developed juvenile color matching the color of their brine shrimp, Artemiu salina,
diet. Larval color thus appeared to develop independently of parent color, although
field-collected larvae exhibited all adult color morphs, usually in colors matching plant
habitats.
Wilkie found no sexual dimorphism between Apodichthys color morphs, while Burgess
did not sex the color morphs. However, Burgess (1976) described some size dimorphism
between red and green color morphs of Xererpes. These authors did not compare the
ability of the fish to change their color on different types of backwoods, nor did they
test color choice and color change ability in different ontogenetic stages and in the two
sexes. Although based on laboratory experiments only, Wilkie’s (1966) and Burgess’
(1976,1978) studies provided a valuable comparison to the present work. Hubbs (1952)
also described widespread color pattern variations in many members of the family
Clinidae.
The present study focused on comparing color change differences in life history stages
and sexes of kelpfish, as implicated by collection studies (Stepien, 1986a,b).
REGULATIONOF KELPFISHCOLORPATTERNS
183
MATERIALSAND METHODS
COLORDESCRIPTION
The Munsell Color System (Munsell, 1946, 1969, 1976) was the standard method of
color designation used in this study. Munsell color designations are readily convertible
to the ISCC-NBS (Inter-Society Color Council, National Bureau of Standard)
Universal Color Language as well as other standard systems (Kelly & Judd, 1976).
Addition~ly, the Munsell System has been the most frequently used standard in other
studies of fish color changes (Wilkie, 1966; Burgess, 1976,1978), allowing comparisons
between these and the present study.
Each color is given a numerical notation for its hue, lightness, and saturation in the
Munsell System. These are termed hue, value, and chroma, and are designated H V/C.
Colors were measured under daylight illumination, against a neutral grey background,
and using neutral grey masks to block out adjacent colors on the charts (ASTM, 1974,
1980). Color of the kelpfish was measured from an area directly posterior to the pectoral
fin. Kelptish having a strong variable pattern of light and dark areas were given two
separate notations, corresponding to average dark and average light colors. Reproducibility of the Munsell System in designating color morphs of kelptish was tested and
found to be highly accurate (Stepien, 1985).
LABORATORY
REARINGEXPERIMENTS
Kelp&h from three hatchings were successfully reared in the laboratory to age
2 months (see Stepien, 1986b for description and methods) and were then used in color
change experiments. The purpose of these experiments was to test the following:
(1) genetic differences in color development in kelpfish larvae having different parents,
(2) similarity of color development on given backgrounds in larvae having the same
parentage, and (3) influence of background color on development of juvenile coloration.
Approximately equal numbers of 2 month-old kelpfish from the three batches were
TABLE I
Munseli colors ofbackgrounds used in color change experiments, indicating average hue, value (brightness),
and chroma (saturation), designated “H V/C”: Munsell hues include red (5 R), green (5 GY), and brown
(10 YR).
Average Munseil hue, value, and chroma notation
Color
Backgrounds
Plastic plants
Red
Green
Gold-brown
Brown
5 R 416
5 GY 4/4
10 YR 616
10 YR 4/4
5 R 316
5 GY 516
10 YR 616
10 YR 4/6
Live plants
5 R 416
5 GY 616
10 YR 6/8
10 YR 4/4
CAROL A. STEPIEN
184
placed in red, green, gold-brown, or brown plastic containers with plastic plants (see
Table I for Munsell color notations of containers). Each 76-1 container had large panels
of 0.3 cm mesh and was placed in an open system of running filtered and aerated sea
water. Lighting for experiments was provided by daylight fluorescent bulbs suspended
over the aquaria and controlled by timers. Additionally, some larvae of the 1980 batch
were tested on black or white backgrounds, as controls for color development in the
absence of color stimuli.
Colors of reared kelpfish were monitored weekly for changes which were documented
with the Munsell System (Munsell, 1976). These young juveniles were fed a diet of
frozen Artemiu salina Hedgepeth (San Francisco Bay brand), live copepods, Tetramin,
and occasionally, live mysid shrimp captured from kelpbeds. One batch was successfully
tested in 1980 and two in 1982. Male parents guarding all nests collected had brown
striped color patterns. Only the male parent and nest were collected for the 1980 batch,
which hatched soon after collection. Both the male and female parents were collected
for the 1982a and 1982b batches, the 1982a batch having a red barred female parent
and the 1982b batch a gold-brown barred female parent.
MARK
AND
RECAPTURE
STUDY
A mark and recapture study was conducted from 1982 to 1984 in order to determine
whether color and habitat changes occurred in situ under natural conditions. Kelpfish
from two locations on Santa Catalina Island, away from other collection sites, were
tagged. No kelpfish were removed from these areas during this study. At least four
SCUBA dives per month were made in these areas. A total of 181 kelpfish > 12 cm TL
were captured and tagged, using a Floy tagging gun and numbered sp~etti-type
tags.
Tags were inserted in the dorsal musculature, just under the dorsal fm and = l/3
distance from the anterior origin of the fin. Sixty-four juveniles (ranging from 5 to
12 cm TL) were tagged with smaller numbered plastic tags which were sewn through
the dorsal musculature and knotted.
Kelpfish were captured while SCUBA diving and data on depth and plant habitat
were recorded, following methods previously described (Stepien, 1985, 1986a). The fish
were brought to the laboratory for a period not > 24 h, where they were measured and
their colors documented under standard conditions with the Munsell System (1976).
The fish were released in approximately the same underwater area and plant habitats
as captured. These procedures were repeated upon recapture. Numbers of recaptured
kelpfish changing habitat and/or color were statistically compared with numbers not
changing using chi-square tests and 95% confidence intervals (Sokal & Rohlf, 1981).
COLOR
CHOICE
EXPERIMENTS
Background color and plant color preferences were tested in laboratory color choice
experiments. Kelpfish were placed in the center of a 122 x 76 x 46 cm aquarium, which
was divided in half, each half having a different color background. Experiments tested
REGULATION
OF KELPFISH COLOR PATTERNS
185
background colors which either matched or did not match the color of the kelpfish. The
following three series of matching vs. non-matching experiments were run (see Table I
for Munsell colors of expe~ment~ back~ounds). (1) Color choice of match~g versus
non-matching artificial backgrounds. Choice between two of red, green, or brown plastic
panels that covered the sides and bottoms of the aquarium. (2) Color choice of matching
versus non-matching red, green, or brown plastic plants. (3) Color choice of matching
versus non-matching red, green, or brown live marine plants. Plants used included red
P~~~arn~~rn
ca~ti~ag~neumDixon, green Ph~l~~spadixtorreyi, and brown Eisenia ar~orea
Areschoug.
Ten individuals were tested independently per experiment. Background color halves
were switched between each trial, compensating for any bias for one half of the
aquarium. The background color chosen by each fish was recorded 15 min after
introduction. It was found that newly introduced kelp&h usually swam around the
aquarium for the first 5 min or so, then settled in one half of the aquarium. If a fish was
still swimming from side to side at the time of recording, it was observed for 5-min
intervals until it “settled” onto one side or another for 5 min or longer. If a kelptish was
located in both halves (across the middle), the half containing its head was recorded
unless > 314 of its body was in the opposite half, in which case the body half was
recorded as the choice. The following individuals were tested. (1) Ten green and 10
brown juveniles. (2) Ten green, 10 brown, and 10 red adult females. (3) Ten brown adult
males.
All of the above were tested in two-choice experiments involving matching versus
non-matching environments. Both non-matching color choices were tested independently against the matching choice. Results of the color choice expe~ments were
analyzed using chi-square tests (Sokal & Rohlf, 1981).
Twenty-three kelpfish from the mark and recapture study were released in multihabitat areas from locations having red, green, and brown plants and their initial
selections of plant cover were recorded. Individual tagged kelpfish were followed while
SCUBA diving for 5 to 20 min after release.
LABORATORY
COLOR CHANGE
EXPERIMENTS
Ability of kelpfish to change color when placed on different backgrounds was tested
in both laboratory and in situ experiments. The following kelpfish were tested in all
experiments. (1) Juvenile kelp&h - green and brown color morphs. (2) Adult female
kelpfish - red, green, and brown color morphs. (3) Adult male kelpfish - brown color
morphs.
Ten individuals of each color morph were tested in each color change experiment.
These individuals were placed in aquaria having red, green, or brown backgrounds.
Controls were also tested, 10 kelpfish of each color being placed on back~ounds
matching their color.
The following laboratory experiments were conducted. (1) Colored background only
186
CAROL A. STEPIEN
(red, green, or brown). (2) Colored background and artificial colored plastic plants (red,
green, or brown). (3) Colored backwood and live marine plants (red, green, or brown;
replaced weekly).
Adult kelptish were tested in 1 x 2 x 1 m divided fiberglass aquaria. Aquaria were
divided with “egg carton” styrene plastic partitions having 1.3- cm divisions and were
painted red, green, or gold-brown using acrylic paints. Juvenile kelpfish were tested in
76-1red, green, and brown-colored plastic containers. The containers had mesh panels
on the sides, retaining the open sea-water flow system. All painted and plastic containers
were matched to approximate the color of in situ plant habitats. Green, brown, and red
plastic aquarium plants were used for artificial plant habitats. The following live marine
plants were used: Eisenia arborea (brown), Plocamium cartilagineum (red), and
Phyllospadix torreyi (green) (see Table I for Munsell color notations of all backgrounds
used).
All laboratory experiments were illuminated by daylight fluorescent lighting on a timer
system. Fish were maintained in a filtered open sea-water system and fed daily. Juveniles
were fed frozen Artemia, Tetramin flake fish food, and frozen squid and adults were fed
the same diet, supplemented with two to three live goldfish per day, which was the
preferred laboratory food. Colors of kelpfish in these experiments were recorded weekly
for 6 wk with the Munsell System (1976). Preliminary experiments determined that this
time interval was sufficient for maximal color changes. Kelpfish left longer in laboratory
experiments did not usually acquire additional new pigmentation.
Color changes were ranked weekly according to amount of change towards the
backwood color. These changes were ranked as + , + + , or + + + . A 0 rating was
recorded for no perceivable hue change, although there may have been a lightness or
saturation change, corresponding to changes in melanin pigment concentration. A
+ rating was recorded if there was a slight change towards the hue of the background
color, but not enough to affect its Munsell hue rating. In other words, the change was
within its Munsell hue, but towards the background hue in color. A + + rating was
recorded if there was a change of 2.5 in Mtmsell hue (i.e. a single hue designation),
towards the ba~k~ound hue in direction. A + + + rating was considered a complete
color change or a “match” in color, and was a change of 5.0 (or two color charts) in
direction towards the background hue.
Color changes were statistically analyzed in comparison with those of the control
experiments using G-tests (also known as &i-square tests). Numbers of fish changing
and not changing color were compared with those from each control. Values of + , + + ,
and + + + were considered to be color changes. Magnitudes of color changes between
experiments of given colors (artificial plants, artificial backgrounds, live plants, and in
situ live plants) were also compared using contingency tables and G-tests (Siegel, 1956;
Sokal & Rohlf, 1981).
REGULATION OF KELPFISH COLOR PATI’ERNS
187
IN SITU COLOR CHANGE EXPERIMENTS
Laboratory color change experiments involving live marine plants of various colors
were duplicated in the field to determine whether results were similar. In situ caged fish
were not fed, but were observed to feed on fishes and crustaceans that entered through
the mesh of the containers. Early attempts at this experiment involving adult kelpfish
placed in large cages on the seafloor failed, the adults mysteriously dying overnight
(Stepien & Brusca, 1985). Juvenile kelp&h, in contrast to the adults, survived in good
health during field cage expe~ents
located in the same areas. Cages cont~ning
juveniles were 0.3 m3 in size with a 0.6cm mesh and the duration of the experiments
was 6 wk. Twelve green and 15 brown juveniles were tested and the results analyzed
using Fisher’s exact test (Siegel, 1956; Sokal & Rohlf, 1981).
Attacks on adult kelpfish (see Stepien & Brusca, 1985) were circumvented by
suspending the cages from a float, 1.5 m below the surface and 4 30 to 40 m off the
seafloor. Color change experiments with juveniles were also repeated in this midwater
set-up in order to determine whether there were color change differences between
demersal and suspended experiments.
In addition to the original 0.3-m3 juvenile cages and I-m3 adult cages, 9.5-l and 38-l
buckets were used as juvenile and adult containers, respectively. These containers had
two large side panels of 0.6-cm mesh and 1.3-cm mesh, respectively, allowing entry of
small fish and crustacean prey. Container experiments were = l/2 ftlled with red, green,
or brown marine plants, which were replaced weekly. Experiments were also monitored
weekly for 6 wk, at which time containers were raised to the surface, kelp&h examined
against neutral gray backgrounds, and their colors compared with Munsell color chips.
Data were recorded and statistically analyzed in an identical manner to those of the
laboratory color change experiments.
Time until onset of + , + + , and + I- + color changes in situ were analyzed using
contingency tables and G-tests and contingency coefficients (Siegel, 1956; Sokal &
Rohlf, 1981). Differences in results between the three series of color change experiments : (1) laboratory artificial plant backgrounds, (2) laboratory live plant
backgrounds, and (3) in situ live plant backgrounds, were similarly statistic~ly
compared.
INFLUENCE
OF DIET
Although diet was not directly tested in laboratory experiments, due to difficulty in
getting many captured kelplish to feed on non-living food and to the relatively large size
of the adults, diet may play a role in color changes. Diet of adults in the wild consists
of crustaceans and small fishes (Quast, 1968; Stepien, 1985, 1986b). Diet of juvenile
kelpfish is primarily composed of amphipods, mysids, and isopods, many of which are
epiphytic (Coyer, 1979).
Numbers of matching versus non-matching invertebrates attached to green, brown,
and red algae were determined in the present study. Live green Phyllospadix torreyi, red
CAROL A. STEPIEN
188
F~~a~~~~ ca~o~~~e~~,and brown Sargassum ~~~~c~~ plants were collected from
subtidal sites and placed in plastic bags. They were soaked in distilled water for 24 h
to kill and remove attached crustaceans, which were rinsed into a 1OOpm mesh.
Invertebrates were then sorted under a dissection microscope and numbers of each
color recorded. Numbers of matching versus non-matching crustaceans on each type
ofglant were compared with chi-square tests (Sokal & RohlfY 1981).
LABORATORY
REARING
EXPERIMENTS
Results from three batches of laboratory-reared kelpfish (1980, 1982a, and 1982b),
contained on red, green, or brown~olored backwoods at age 3 months, indicate that
juvenile color development is environmentally induced and apparently independent of
parent color. Color development was virtually identical on given backgrounds between
each of the three rearing studies (Table II). Kelpfish in green containers developed green
pigmentation, while those in gold, brown, and red containers developed brown
~hromatophores. The majority of kelpfish in al1 experiments had assumed juvenile
brown or green pi~entation by age 4 to 5 months (Table II).
Kelpfish on white backgrounds developed pale brown pigmentation, while those on
black backgrounds became dark brown in color (Table Ila). These results suggest that
(shades of) brown is a “default” color, which develops in the absence of background
stimuli. Shades of individual hues were apparently produced by variable number of
Mack mel~ophores and their various states of expansion or contraction; kelp&h on
lighter backgrounds developing fewer melanophores, the majority of which were
contracted and those on darker backgrounds developing more melanophores which had
dispersed melanin. Gold and brown colors differed primarily in that brown fish
possessed a greater number of melanophores.
The most successful rearing experiment, the 1980 experiment, resulted in juveniles
reaching a maximum age of 9 months, at which time they succumbed to a bacterial
infection. This 1980 batch began with 92 reared kelpfish at 2 months, ending with 34
at 9 months. The 1982a batch began with 46 larvae at 2 months, ending with 19 at
5 months. The 1982b batch began with 35 at 2 months, ending with 10 at 4 months (see
Stepien, 1986b).
COLOR CHOICE
EXPERIMENTS
When given matching versus non-matching choices of two red, green, or browncolored panels, kelpfish showed no overall preferences for any color {Tabie IHa).
~nsi~i~~~t results were obtained in testing juvenile, adult male, and adult female
keIpfish on these artificial backgrounds. Wben presented with choices between artificial
plant backgrounds of matching versus non-matching colors, adult kelpfish (both males
0
Green
:
;
0
0
0
0
Gold
(23s)
Brown
(23313)
Black
~23~12)
White
(23%
++
G
++
G
2
L
+++
B
+++
B-G
++
B-G
++
G
++
B-G
++
G
+
G
++t
B-G
++“I”
G
++
G
++
G
(++)
G
Gr
+++
5
:
Gr
++
4
(++)
G
YZR
3
(+)
G
(+)
G
Y-GR
+
2
Monthly color changes
“4-“t
G
+c+
B
G
+t
+++
B
B
ttt
+tt
B
+-I-+
G
(+++)
G
Gr
tt+
7
+++
G
(+++)
G
Gr
+++
6
Final Munsell
color range
Munsell colors
10 YR 7/6-6/10
5-10 YR .5/4-4/8
10 YR 5/4-4/8
5-10 YR 7/6-6/10
10 YR 6/6-5/8
5-10 Y 6/4-5%
backgrounds:
Number of fish at start, at end indicated: 0, start or no change; + , slight change; + + , moderate change; + + + , complete change; fish colors: Gr, green;
Y-GR, yellow-green; G, gold; B, brown; B-G, brown-gold; ( ), nan-matching change to gold or brown.
0
d
0
0
0
1
Red
(23.7)
&?3,9)
a
Background
color
TABLE IIa
kelpfish of known parent color on red, green, and brown-colored
indicated.
Color development of kelpfish juveniles on colored backgrounds in 1980 experiments.
Color development experiments for laboratory-reared
TABLE IIa,b
CAROL A. STEPIEN
190
TABLE KKb
Color development of kelpfish juveniles on colored backgrounds in 1982 experiments.
Monthly color changes
NOS.
Backaround
cofor
Batch A
Green
Red
Gold
Brown
(start,
‘end)
(12,8)
(l&8)
(11,2)
(IU)
0
1
2
3
Final Munsell
color range
2.5-10 Y 8/4-618
+
++
++
G-Gf
G-Gr
G-Gr
(+f
G
(+)
(++“I
G
0
r;
A
ii
ff
G
i”+
10 YR S/4-6/8
10 YR 814-618
G
&;
X5-10 YR 7/J-S/10
Batch B
Green
(993)
2.5-10 Y &/4--6/S
Red
(931)
5-10 YR 7/4-6/10
Gold
(9-4)
IO YR 7/4-i$lO
Brown
W)
2.5-10 YR 7/4-5/8
Fish colors: Gr, green; G, gold; B, brown; G&r, gold-green; G-B, gold-brown; color changes: f ),
non-matching change to gold or brown; 0, start or no change; t , slight change; + f , moderate change;
+ + + , complete change.
and females) significantly preferred the matching choices (Table IIIb). Juveniles showed
some significant preferences for matching back~ounds, inc~u~g brown juveniles
choosing brown over red backgrounds. However, overall juvenile preferences in
artificial plant experiments were not signi&caut. Green adult females also did not
significantly prefer green backgrounds in these experiments.
Choice experiments involving matching versus non-matching colors of live marine
plant yielded significant preferences for matching backgrounds in ah groups tested
(Table I&). There was no significant Werence between plastic plant and live plant
experiments in overall numbers of kelpfish choosing matching over non-matching
backgrounds (Table III).
Kelptish released in situ after tagging did not usually choose their original species of
plant habitat, hiding instead in the first encountered plant habitat (Table IV). Many were
chased away from cover by kelpfish with beady-estab~sh~
territories in these plants,
Most kelpfish that were followed for longer periods of time or seen during subsequent
dives, changed habitats, leaving their initial cover. In these cases, the majority changed
REGULATION
191
OF KELPFISH COLOR PATTERNS
to plants matching their color, but not always the original species upon which they were
collected before tagging.
MARK
AND
RECAPTURE
STUDY
Recapture rate of tagged kelpfish was fairly low, 32 of 28 1 tagged, or 11.2 % . Of these,
only three changed color morph and only six changed habitat color (Table Va).
Incidence of no change in both cases was statistically significant, indicating that few
juvenile and adult kelptish changed color morphs or habitat color in situ. However,
changes to habitats of the same color but different species, were significantly common
(Table Vb).
Small juveniles (5 to 11 cm) tagged with smaller tags were not successfully recaptured,
probably due to high mortality levels, as indicated in laboratory tagging experiments.
TABLE IIIa-c
Color choice experiments
utilizing
matching
versus non-matching
red, green, or brown-colored
backgrounds:
results of chi-square tests indicated; *, significant difference, 0.05 alpha level (x2 = 3.84);
N = 120; a, artifical plastic panel backgrounds;
b, plastic plant experiments;
c, live plant backgrounds,
including green Phyllospadix torreyi, red Plocamium cartilagineum, and brown Eisenia arborea; contingency
table tests of independence
showed significant differences between the results obtained for experiments
involving artificial backgrounds
versus plastic plants (x2 = 10.15*, P < 0.005) and artificial backgrounds
versus live plants (x2 = 13.02*, P < 0.001); there were no significant differences between results obtained
for the plastic plant versus live plant experiments.
TABLE IIIa
Artificial
Kelpfish
tested
Brown juveniles
Green juveniles
Brown males
Brown females
Green
females
Red females
Plant color
choices
background
color choice experiments.
Matching
choice
Non-matching
choice
x2
values
Brown-Green
Brown-Red
Green-Brown
Green-Red
Subtotal
5
6
2
4
17
5
4
8
6
23
0.00
0.40
3.60
0.40
Brown-Green
Brown-Red
Subtotal
6
7
13
4
3
I
0.40
1.60
Brown-Green
Brown-Red
Green-Brown
Green-Red
Red-Brown
Red-Green
Subtotal
4
6
3
5
6
8
32
2
28
Total
62
58
0.40
0.40
1.60
0.00
0.40
3.60
x2
totals
0.20
3.20
0.90
1.80
1.80
0.00
0.80
3.20
0.27
0.13
CAROL
192
A. STEPIEN
TABLE IIIb
Plastic plant color choice experiments.
Kelptish
tested
Brown juveniles
Green juveniles
Brown males
Brown females
Green
females
Red females
Plant color
choices
Matching
choice
Non-matching
choice
Brown-Green
Brown-Red
Green-Brown
Green-Red
Subtotal
6
9
3
26
Brown-Green
Brown-Red
Subtotal
9
I
16
Brown-Green
Brown-Red
Green-Brown
Green-Red
Red-Brown
Red-Green
Subtotal
6
10
5
7
7
9
44
1
16
86
34
8
x2
values
4
1
I
2
14
0.40
6.40*
1.60
3.60
1
3
4
6.40*
1.60
0.40
10.00*
0.00
1.60
1.60
6.40*
x2
totals
5.00*
0.20
3.60
7.20*
7.20*
7.20’
0.80
7.20*
13.07*
22.53*
TABLE IIIc
Plant color choice experiments.
Kelptish
tested
Brown juveniles
Brown males
Brown females
Green
females
Red females
Plant color
choices
Brown-Green
Brown-Red
Green-Brown
Green-Red
Subtotal
Brown-Green
Brown-Red
Subtotal
Matching
choice
Non-matching
choice
x2
values
0.40
0.00
1.60
3.60
26
4
5
3
2
14
10
8
18
0
2
2
10.00*
3.60
6
5
7
8
Brown-Green
Brown-Red
Green-Brown
Green-Red
Red-Brown
Red-Green
Subtotal
8
45
2
15
Total
89
31
1.60
3.60
0.40
6.40*
1.60
3.60
x2
totals
0.20
5.00*
3.60
12.88*
12.88*
5.00*
5.00*
5.00*
15.00*
28.03*
193
REGULATION OF KELPFISH COLOR PATTERNS
TABLE IV
Plant choices of kelptish followed after release in situ: initial plant choices are recorded (including changes,
if two listed); kelpfish color, melanin pattern, and total length (cm) are given; color and species of plant
habitat originally collected on and that chosen after release are indicated; plant species: Mac. = Macrocystis
pyrifera, Eis. = Eisenia arborea, Cyst. = Cystoseira neglecta, Zen. = Zonaria (Laminaria) farlowii,
Sarg. = Sargassum mukxm,
Phy. = Phyllospadix torreyi, Gel. = Gelidium nud?ons, Plo. = Plocamium
cartilagineum, Cor. = Corallina sp., Pter. = Pterocladia capillacea; turf = short, unidentified brown algae.
Orig. habitat
Fish color
Brown
Mel. patt.
Plain
Barred
Striped
Mottled
Green
Plain
Barred
Striped
Mottled
Red
Barred
Habitat chosen upon release
TL
Orig.
color
Orig.
species
Choice
color
21.2
26.9
17.4
23.0
22.0
22.3
32.0
21.0
20.6
23.4
18.0
19.3
22.6
24.1
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Mac.
Mac.
Mac.
Mac.
cyst.
Eis.
Mac.
cyst.
Zon.
Sarg.
Eis.
Eis.
Mac.
Sarg.
Brown
Brown
Brown
Brown
Brown
Brown-Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Brown
Mac.
Eis.
Mac.
EiS.
23.3
17.3
26.2
14.7
14.2
Green
Green
Brown
Green
Green
Phy.
Phy.
cysr.
Phy.
Phy.
Brown
Green-Brown
Brown
Green
Brown-Brown
Mac.
28.5
17.2
26.2
21.1
Red
Red
Red
Red
Gel.
Cor.
Plo.
Pter.
Brown-Red
Brown
Brown
Brown
Mar.-Gel.
Mac.
Mac.
Eis.
Choice
species
turf
Sarg.-Mac.
Mac.
EiX
Mac.
Mac.
Mac.
Mac.
Mac.
Eis.-Mac.
Phy.-turf
Mac.
Phy.
Cyst. -Mac.
Unlike small juveniles, larger juveniles and adults rarely exhibited increased
vulnerability to infections after tagging, although z 10% of the tags eventually became
dislodged in laboratory experiments. A few dislocated tags were found on the seafloor
in kelptish tagging areas and some untagged captured fish had scars indicating that they
had been previously tagged.
COLOR CHANGE EXPERIMENTS
Results of laboratory color change experiments on artificial panel and plant
backgrounds indicated that juvenile kelp&h readily changed color from green to brown
and vice versa (Table Via). Juveniles on red-colored backgrounds became or remained
brown. Unlike juveniles, adults in artificial background experiments did not exhibit
CAROL A. STEPIEN
194
TABLE Va,b
Summary of results of mark and recapture study: chi-square values shown for tests of numbers changing
versus numbers not changing color or habitat (tested against equal ~ssi~ity of changing or not changing);
* = significant at 0.05 level (x2 = 3.84); numbers and sizes of kelpfish changing color morphs and habitat
colors indicated; B, number ofmark and recapture kelpfish changing plant species (but in same color)versus
number recaptured in same plant species.
TABLE Va
Mark and recapture study: N = 281 tagged, 32 recaptured, 11.2%; sizes (TL, cm) of kelp&h changing in
parentheses.
Original
fish color
Green
Number
recaptured
Size
range
4
Number
color changes
14.3-35.3
$3)
Brown
25
(1j.3)
15.3-34.5
(157717.3)
Red
Number habitat
color changes
3
26.2-29.5
(17.3,2:0,26.4)
0
(262226.6)
Total recap.
32
6
3
x2 (number of color changes vs. number expected) = 21.13*
x2 (number of habitat color changes vs. number expected) = 12.50*
TABLE Vb
Number of mark and recapture fish changing plant habitats.
Fish
color
No. changing
plant sp.
Green
Red
Brown
Total
x2
=
No. in same
plant sp.
1
3
25
3
0
10
29
13
6.10*
significant changes (Table VId). Most adults maintained their original color, with some
fading to brown.
Laboratory experiments utilizing live plant backgrounds resulted in significant color
changes to green and brown for both juveniles (Table VIb) and some female adults
(Table Vie). Three adult males changed to an olive brown-green color on green
backgrounds (Table Vie), but the majority did not change. Some green females on
red back~ou~ds became brown in color. Some red and brown females on green
backgrounds developed green pigmentation. No changes to red were obtained in these
experiments.
195
REGULATION OF KELPFISH COLOR PATTERNS
Via-f
TABLE
Color change experiments for juvenile and adult kelptish on red, green, and brown-colored backgrounds:
in control groups, color of fish matched the background color; chi-square results indicated for differences
between control and experimental groups; * si~~~cant difference at 0.05 level (x2 = 3.84); Mx2 = change
to matching color of plant background (vs. changes to all other color morphs); N per experimental
group = 10. a, laboratory color change experiments with juveniles on artificial backgrounds, N = 60;
d, laboratory color change experiments with adults on artificial backgrounds, N = 60; b, laboratory color
change experiments with juveniles on live marine plant backgrounds, N = 60; e, laboratory color change
experiments with adults with live marine plant back~ounds, N = 120; c, in situ suspended color change
experiments with juveniles on live marine plant backgrounds, N = 120; f, in situ suspended color change
experiments with adults on live marine plant backgrounds, N = 120. Significant differences (P < 0.05) were
obtained with contingency table tests of independence in comparing results of the following sets of
experiments: (1)experiments with adult kelp&h: laboratory plants versus field plants (x2 = 13.11*,
P -c 0.001); artificial backgrounds versus field plants (x2 = 25.29’. P -=z0.001). (2) Experiments with juvenile
kelpfish: artificial backgrounds versus laboratory plants (x2 = 4.04*, P < 0.05). (3) differences between
results with juveniles versus adults; artificial backgrounds (x2 = 24.87*, P < 0.001); laboratory plants
(x2 = 27.90*, Pi 0.001); field plants (x2 = 6.46*, P < 0.025); results of all experiments (x2 = 46.02*,
TABLE Via
Juvenile laboratory color change experiments with artificial backgrounds.
Numbers of each final fish color
Original
color
Background
color
Brown
Brown
Brown
Green
Red
10
2
10
Green
Brown
Green
Red
9
0
7
Red
Chi-square
values
0
8
0
0
0
0
Control
13.334
NS
1
10
3
0
0
0
NS
Control
10.77*
Green
TABLE VIb
Adult laboratory color change experiments with artificial back~ounds.
Numbers of each final fish color
Original
color
Brown males
Background
color
Brown
Green
Red
Chi-square
values
Green
Red
10
10
10
0
0
0
0
0
0
Control
20.00*
NS
Brown .females
Brown
Green
Red
10
10
10
0
0
0
0
0
0
Control
NS
NS
Green females
Brown
Green
Red
3
0
2
I
10
8
0
0
0
3.53
Control
2.22
Red females
Brown
Green
Red
1
2
1
0
0
0
9
8
9
NS
0.39
Control
Br0Wll
CAROL
196
A. STEPIEN
TABLE WC
Juvenile
laboratory
color change
experiments
Numbers
Background
color
Original
color
Green
and background
colors.
of each final fish color
Brown
Green
0
10
0
0
10
1
10
0
10
10
0
9
Brown
Green
Red
Brown
Green
Red
Brown
with plants
Red
Chi-square
values
0
0
0
0
0
0
Control
20.00*
NS
20.00*
Control
16.36
TABLE VId
Adult laboratory
color change
experiments
with plants
Numbers
Original
color
Background
color
Brown
and background
colors.
of each final fish color
Green
Red
Chi-square
values
Brown males
Brown
Green
Red
10
I
10
0
3
0
0
0
0
Control
3.53
NS
Brown females
Brown
Green
Red
10
5
10
0
5
0
0
0
0
Control
6.6F
NS
Green
Brown
Green
Red
6
0
4
4
10
6
0
0
0
a.57*
Control
5.00*
Brown
Green
Red
2
3
0
0
2
0
8
5
10
2.22
6.6F
Control
females
Red females
Juvenile kelp&h in caging experiments on the seafloor also significantly changed
between green and brown color morphs (Table VII). The majority of these changes were
large in magnitude ( + + or + + + ). These results closely approximated those obtained
with cages suspended in the water column (Table VIc), a procedure necessary for
success of in situ experiments with adults (see Materials and Methods). Adults in field
caging experiments showed more color changes than did laboratory experiments
(Table VI). Some adult females (both green and brown) assumed red pigmentation on
red backgrounds. A few adult males on green backgrounds became olive green-brown
in color. As in other experiments, no juveniles assumed red pigmentation (Table VIc).
REGULATION OF KELPFISH COLOR PATTERNS
197
TABLE Vie
Juvenile field color change experiments.
Numbers of each final fish color
Original
color
Background
color
Brown
Green
Red
Brown
Brown
Green
Red
10
0
10
0
10
0
0
0
0
Green
Brown
Green
Red
10
0
8
0
10
2
0
0
0
Chi-square
values
Control
20.00*
NS
20.00*
Control
13.33*
TABLE VIf
Adult field color change experiments.
Numbers of each final fish color
Background
color
Brown
Brown males
Brown
Green
Red
10
6
10
0
4
0
0
0
0
Control
5.00’
NS
Brown females
Brown
Green
Red
10
2
3
0
8
0
0
0
7
Control
13.33*
10.77*
Green females
Brown
Green
Red
7
0
2
3
10
2
0
0
6
10.77*
Control
13.33*
Mx2 = 8.57*
Brown
Green
6
5
4
4
8
1
Red
0
10
0
8.57*
18.36*
Mx2 = 5.00*
Control
Original
color
Green
Red
Red females
Chi-square
values
Contingency table tests of independence showed that numbers of adult kelpfish
changing color on live plant backgrounds were significantly greater in field than in
laboratory experiments (Table VI). Juveniles, in contrast, changed equally well in live
plant experiments conducted in the laboratory and in situ. Color change frequencies of
juveniles were significantly greater than those of adults in all three series of experiments
(laboratory artificial backgrounds, laboratory live plant backgrounds, and in situ live
plant backgrounds). Largest differences between juveniles and adults were obtained in
laboratory experiments.
CAROL A. STEPIEN
I98
TABLE VII
Color change experiments with juvenile kelpfsh in cages on the seafloor: green and brown juveniles tested
on red, green, and brown plant habitats; changes compared with control groups in which kelpfish matched
the background color; Fisher exact test results and probabilities indicated.
Original
fish color
Background
color
Final
color
Brown
Brown (5)
Green (7)
Brown (5)
Green (7)
3++,4+++
Control
P = 0.0013*
Green (6)
Brown (9)
Green (6)
Brown (9)
3++,6+++
Control
P = 0.0018*
16116
6++,10+++
P < 0.0001
Green
Total changing
with background
Change
magnitudes
Fisher exact
test results
*, Signi~cant difference between control and experimental groups at 0.05 level; + , slight color change; + + ,
moderate color change; + + + , complete color change.
TABLE VIIIa-c
Magnitude comparisons for color change experiments, including artificial background, laboratory plant
background, and in situ plant background experiments: + , slight color change towards background hue on
Munsell scale; + + , moderate change towards background hue on Munsetl scale; + + + , complete change
in matching color morph on Munsell scale; ( ), change to brown color, not the matching color; N per
experiment = 10; a, experiments with juvenile kelp&h; b, experiments with adult kelptish; c, contingency
table tests of independence comparing color change magnitudes within and between experiments using
juveniles and adults; chi-square values and probabilities indicated.
TABLE VlIIa
Ma~itude
Fish
color
of color changes in experiments with juvenile kelpfish.
Background
color
Number
of
changes
Laboratory experiments with artificial backgrounds
Brown
Green
S/IO
Green
Brown
S/IO
Green
Red
(7/10)
Total
24
Laboratory experiments with plants and backgrounds
Brown
Green
lo/lo
Green
Brown
lo/IO
Green
Red
(9110)
Total
Field experiments with plant backgrounds
Brown
Green
Green
Brown
Green
Red
Total
Total (all expts.)
Magnitude of color changes
+
++
+++
2
4
2
(:)
(42)
(i)
8
10
6
0
2
8
d)
(5)
(:)
29
3
6
20
lo/IO
IO/l0
(S/IO)
0
2
8
(t
(i)
b)
28
1
5
22
81
12
21
48
REGULATION
OF KELPFISH
COLOR
PATTERNS
199
TABLE VIIIb
Magnitude
Fish color
and sex
of color changes
in experiments
Background
color
Laboratory
experiments
Red female
Red female
Green female
Green female
with artificial background
Brown
Green
Brown
Red
Total
Laboratory
experiments
Brown male
Brown female
Red female
Red female
Green female
Green female
with plants and backgrounds
Green
Green
Brown
Green
Brown
Red
Total
Field experiments
Brown male
Brown female
Brown female
Red female
Red female
Green female
Green female
Total
Total (all expts.)
Number
of
changes
l/l0
2/10
3/10
2/10
Magnitude
of color changes
+
ct
2
0
8
3
3/10
5/10
2/10
5/10
4/10
4/10
3
1
1
23
with plant backgrounds
Green
Green
Red
Brown
Green
Brown
Red
with adult kelpfish.
2 (2)
(32)
14
4/10
8/10
7110
6/10
9/10
7/10
S/l0
0
4
0
1
:
)
8
1
3
3
1
0
4
2
4(l)
0
2
(:)
6
l(2)
49
10
15
24
80
27
28
25
Magnitudes of color changes ( + , + + , and + + + ) are reported in Table VIIIa
(juveniles) and VIIIb (adults). The most complete color changes involving juveniles were
obtained in laboratory and in situ experiments utilizing live plant backgrounds.
Although results of laboratory experiments with adults and live plants showed some
magnitude increases over those with artificial backgrounds, only in situ experiments
yielded high-magnitude changes. Table VIIIc gives results of tests of independence
comparing numbers of various magnitudes of changes between experiments. These
results indicate that juveniles and adults differed significantly in distributions of
magnitudes in the same experiments.
Onset times (in weeks) for various magnitudes of in situ color changes are presented
in Table IXa. These results show that changes occurred gradually, usually commencing
in the first 1 to 3 wk and proceeding through + , + + , to + + + magnitudes. Mean and
range times for magnitude changes are given. Complete color changes occurred in 3 to
CAROL
200
A. STEPIEN
TABLE VIIIc
Tests of independence
for color change
magnitudes within and between
adults.
of + ,
+ + , and + + + changes between experiments
A Artificial backgrounds
vs. laboratory plants
B Laboratory
plants vs. field plants
C Artificial backgrounds
vs. field plants
2 Distribution
of + ,
A Artificial backgrounds
vs. laboratory plants
B Laboratory
plants vs. field plants
C Artificial backgrounds
vs. field plants
A Artificial backgrounds
B Laboratory
plants
C Field plants
Total juveniles
vs. adults (all expts.)
and
between
with adults
N.C.
17.34* (<O.OOl)
N.C.
+ + , and + + + changes between experiments
3 Distribution of + , + + , and + + + changes
vs. experiments with adults
using juveniles
Chi-square value
(and probability)
Experiment
1 Distribution
experiments
with juveniles
10.43* (<O.Ol)
1.17
16.04* (<O.OOl)
experiments
with juveniles
N.C.
24.22* (<O.OOl)
6.90* (< 0.05)
13.31* (<O.OOS)
*, Significant difference 0.05 level; ( ), probability levels; + , slight change; + + , moderate
complete change; N.C., not calculated, since some expected frequencies ~5.
change;
+ + +,
6 wk. Juveniles showed faster times for mean onset and completion of color changes
than did adults. Table IXb gives statistical comparisons between onset times of various
change magnitudes in juveniles and adults. Results indicated significant differences in
onset times for all magnitudes of changes, juveniles changing faster than adults.
INFLUENCE
OF DIET
Although diet was not varied in these experiments, cryptic crustaceans found on live
plant habitats may be consumed by kelpfish. Table X indicates that significantly large
numbers of small crustaceans on green, brown, and red plant habitats matched the
plants in color. Colorless crustaceans, as well as those having matching pigmentation,
were included in the matching category. These epiphytic crustaceans included z 80%
gammarid amphipods, 5% caprellid amphipods, and 10% isopods.
Observations of in situ feeding by uncaged kelpfish showed that adults often foraged
several meters away from their “home” plants, pursuing fishes and crustaceans,
including larger shrimps and crabs. Feeding was more frequent in early morning and
late afternoon hours, kelpflsh more often hiding at midday. Juvenile diets consisted of
smaller crustaceans, primarily amphipods, mysids, and isopods. Examination of gut
contents did not indicate any apparent dietary differences between color morphs. Colors
of ingested crustaceans were indeterminable.
201
REGULATION OF KELPFISH COLOR PATTERNS
TABLE IXa,b
Time (wk) until onset of color changes of various magnitudes in field caging experiments: a, mean time (wk)
until onset of color changes of various magnitudes; b, contingency table tests of independence for times until
onset of color changes in juvenile versus adult kelpfish; G (chi-square) test values, probabilities, and
contingency coefficients indicated.
TABLE IXa
Mean time (wk) until color changes in field caging experiments.
Mean and range time until changes
of each magnitude (wk)
Fish
color
Background
color
Number of
changes
+
++
Juvenile kelptish
Brown
Green
Green
Green
Brown
Red
lo/lo
IO/IO
7110
1.2 (l-2)
1.5 (l-2)
1.7 (l-3)
3.0 (2-4)
2.7 (2-4)
2.7 (2-4)
Adult male kelpfish
Brown
Green
4/10
2.0 (2)
4.0 (4)
Adult female kelpfish
Brown
Green
Brown
Red
Red
Brown
Red
Green
Green
Brown
Green
Red
S/l0
7110
6/10
9/10
7110
S/10
2.8
2.7
2.7
2.6
2.7
2.0
3.4
3.6
3.8
3.8
3.7
2.6
(2-4)
(2-4)
(2-3)
(2-4)
(l-4)
(l-3)
(2-6)
(3-5)
(3-5)
(2-5)
(3-4)
(l-4)
+t+
4.0 (3-5)
3.5 (3-4)
3.5 (2-5)
5.5
5.5
4.0
5.2
5.0
5.0
(5-6)
(5-6)
(3-5)
(4-6)
(4-6)
(4-6)
+ , slight change; + + , moderate change; + + + , complete change.
DISCUSSION
Adult kelpfish in color choice experiments more frequently chose matching over
non-matching backgrounds in the cases of both artificial and live plant backgrounds.
This preference was not true for flat plastic panel backgrounds, indicating that such
response is to colored plant forms, but not to color alone. Choices made by juvenile
kelpfish were less pronounced and more inconsistent than those of adults. Similar
results were obtained for algal background choices in red, green, and brown color
morphs of ~p~jc~t~y~~a~d~
(Wilkie, 1966) and Xerelpes fuconm (Burgess, 1976,
1978). The results of the present study, together with the high frequencies of kelpfish
color morphs collected on matching plant habitats (Stepien, 1986a), indicate that
kelpfish actively select matching backgrounds.
Mark and recapture experiments, although low in recapture numbers due to the
cryptic behavior of kelp~sh, showed that relatively few changed color morph or habitat
color over long periods of time (several months). The few color changes that occurred
were restricted to juveniles and adult females. The majority of released kelpfish hid in
CAROL A. STEPIEN
202
TABLE IXb
Tests of independence for times until onset of various color change magnitudes in juvenile vs. adult
kelpfish.
G-value
Time until change (wk)
Experiment
1
2
3
4
-._____
5
6
P-level
and CC-value
Number of kelpfish
1 + Magnitude changes
A Juvenile kelptish
B Adult kelp&h
2 t + Magnitude changes
A Juvenile kelpfish
B Adult kelp&h
3 + + + Magnitude changes
A Juvenile kelp&h
B Adult kelpfish
18
11
13
0
-
-
G = 17.61*
(3 d.f.)
P = <O.OOl
CC = 0.42
2
18
19
2
-
-
0
10
12
5
0
-
G = 15.95*
(4 d.f.)
2
3
Ii
17
5
-
P = <o.oos
cc = 0.44
1
9
12
3
0
G = 18.98*
(4 d.f.)
0
1
7
8
8
P= <O.ool
cc = 0.53
+ , slight color change; + + , moderate color change; + + + , complete color change; *, signiticance at 0.05
level; d.f., degrees of freedom; G, chi-square vafue; CC, contingency coefftcient.
the first available cover, later changing to a matching habitat color. Although kelpfish
with established territories did not usually change habitat color, they frequently changed
species of plant habitat over several months of observation.
Color change experiments showed that long-term rno~holo~c~
changes in
Heterostichus color morphs occurred in response to plant habitat color. These involved
slow changes in amounts and chemical composition of integumentary carotenoid
pi~ents, which were found to differ si~~~~tly
between the three morphs (Stepien,
1985). Such long-term morphological changes differ from short-term physiological
changes in terms of relative persistence and controlling mechanisms (Bagnara &
Hadley, 1973). Physiological color changes involve expansion or contraction of pigment
granules within ~~omatophores, the majority of these involving mel~ophores (Fujii,
1969; Bagnara & Hadley, 1973). Most studies of color changes in response to
backgrounds have focused on melanin changes (Von Frisch, 1911; Parker &
Rosenblueth, 1941; Parker, 1948; Waring, 1963; Fujii, 1969), rather than on
morphological changes.
Kelptish often exhibited rapid lightening and darkening due to changes in melanin
deposition within melanophores (Stepien, 1985, 1986a). These physiological color
203
REGULATION OF KELPFISH COLOR PATTERNS
TABLE Xa,b
Colors of small epiphytic crustaceans on green, brown, and red subtidai plant habitats: a, crustacean colors
on each habitat; b, &i-square tests of matching versus non-matching crustaceans on each habitat; *,
significant difference at 0.05 level (x2 = 3.84).
TABLE
Xa
Colors of small crustaceans on plant habitats.
Number of crustaceans of each color
Plant habitat
Clear
Green
Brown
Red
Totals
Phyllospadix (Green)
Sargassum
(Brown)
21
16
43
53
6
16
36
178
14
9
2
59
119
202
132
80
75
228
70
453
PIocamium
(Red)
Totals
TABLE
Xb
Numbers of small crustaceans matching vs. not matching plant habitats.
Not
matching
Chi square
Plant habitat
Matching
Phyllospadti (Green)
Sargassum (Brown)
Plocamium (Red)
74
45
184
102
18
30
136.42*
39.27*
Totals
360
93
157.37*
changes
appeared
occurred
in response
to background
to be used in intraspecific
changes
communication
7.07*
and light ~tensiti~s
(Stepien,
and also
1986a). Melanophore
changes in fishes are well known to be under neural and hormonal control (Waring,
1963; Bagnara& Hadley, 1973; Brown, 1973). In contrast, comparatively little is known
of the mechanisms governing morphological color changes, which involve gain and loss
of pigments and occur more slowly (Waring, 1963; Bagnara & Hadley, 1973; B&ten,
1983).
Ability of kelpfish juveniles, adult males, and adult females to change color morph
with long-term exposure to differently colored plant habitats was extensively tested in
the present study. Juvenile color patterns in three batches of laboratory-reared
larvae
from known parents appeared to develop independently
of parental color. These results
indicate that assumption
of brown or green color by juveniles was governed by
background
color alone. Color changes in juveniles
occurred on artificial plant
backgrounds
and were not due to dietary differences, since kelpfish in all experiments
204
CAROL A. STEPIEN
were fed a common diet. Although development of juvenile color appeared determined
by backwood color alone, it remains ~~0~
whether parental color ~~uences adult
color, since laboratory-reared kelpfish were not successfully maintained to adulthood.
Color change experiments supported results obtained from field collections indicating
that color morph frequencies differ between juveniles and adults and between adult
males and females (Stepien, 1986a). Sexual dimorphism between adult males and adult
females (changes to red and retention of ability to become true green being limited to
females only), indicates that adult color is either genetically determined or regulated by
sex hormones or both. Mo~holo~c~
color differences between males and females,
including those accompanying protogynous sex reversals, are believed to be ho~on~ly
controlled (Stoll, 1955; Okada, 1962, 1964; Fujii, 1969). In some sexually dimorphic
fish species, treatment of females with testosterone has resulted in the appearance of
male coloration (Stoll, 1955; Okada, 1964; Roede, 1972). Discrepancies between
results of color change experiments (i.e. not all females changing color with background
in field experiments) indicate that ability to change morphs varies between individuals.
This was also true of adult males, only some of those placed on green plants assuming
olive green pigmentation.
Juveniles were capable of more rapid and complete changes than adults, usually
changing within 1 to 2 wk. Unlike adults, juveniles became green on artificial green
backgrounds. Adult kelplish changes on artiticial backgrounds were limited to slower
“fadings” to brown, which appears to be the “default” morph. Juveniles and adults
placed on black or white backgrounds in laboratory experiments likewise became
brown, losing other pi~entation within a few weeks. Both juveniles and adult females
developed green pi~entation on green Phy~~osp~d~xbackgrounds in laboratory experiments. It appears that changes to green in adults require live plant backgrounds. It is
unknown whether these color changes are evoked by plant backgrounds only or whether
there is a dietary component influencing adult changes.
Laboratory diet was designed to provide kelpfish with appropriate pigmentary
precursors, simulating natural levels of dietary carotenoids. Pigments contained in
Artem& have been determined to be astaxanthin (Gilchrist & Green, 1960) and
c~th~~thin
(Hata & Hata, 1969; Davies et al., 1965, 1970). Those of live goldfish
have been found to include canthaxanthm, lutein, and astaxanthin (Hata & Hata, 1971).
Tetramin flake fish food contains some canthaxanthin (Fey & Meyers, 1980). Kelpflsh
fed squid alone were found to gradually fade to a pale brown.
Although laboratory adults were fed a common diet of live goldfish, squid, Tetramin,
and frozen Artemia, there is a possibility that they additionally consumed some of the
live marine plants and/or associated epiphytic crustaceans. In fact, gut contents of
meld-collects adult kelpfish contained some algae and small crustaceans, primarily
amphipods, in addition to larger crustaceans and fishes that comprised the majority of
their diet. No dietary differences, however, were observed between red, green, and
brown morphs. Additionally, some kelpfish in the laboratory were observed to pick up
algae.
REGULATION
OF KELPFISH COLOR PATTERNS
205
The majority of epiphytic crustaceans (composed of z 90% amphipods and 10%
isopods) on green Phyllospadix, red Plocamium, and brown Eisenia matched the plant
color. Lee’s (1966, 1972) study of red, green, and brown color morphs of the isopod
Zdotea montereyensis indicated that they developed colors matching plant backgrounds
independently of diet, being capable of converting pigmentary precursors into a variety
of integumentary pigment forms. Wilkie (1966, pers. comm.) found that laboratoryreared larvae of the penpoint gunnel Apodichthysflavidus developed color matching their
Artemia diet, independently of background gravel color. As in the present study, these
larvae appeared to develop juvenile color independently from parental color; but unlike
the present study, they were not influenced by background. Live or artificial marine
plants were not used in Wilkie’s study.
Wilkie (1966) and Burgess (1976, 1978) found that red, green, and brown color
morphs in Apodichthysflavidus and Xererpes fucorum, respectively, were capable of only
limited color changes in laboratory experiments with colored gravel backgrounds. Their
results appear similar to those obtained for kelpfish on the artificial painted
backgrounds. The “changes” reported in their experiments are stated to have involved
a “fading” to brown or an unmasking of already-present pigment, rather than acquisition of new pigments. Only + and, rarely + + , changes in magnitude (incomplete
changes) were obtained by Burgess, when his Munsell results are converted to the
magnitude notations used in the present study. Wilkie concluded that color in
Apodichthys juveniles is initially determined by diet, after which it appears to be fixed
throughout adulthood. He postulated that color morphs were determined after settlement on red, green, and brown plant habitats by diets of matching epiphytic crustaceans.
Results of the present laboratory experiments (conducted prior to in situ studies)
suggested that color of adult kelpfish was similarly inflexible, in contrast to that of
juveniles; changes in adults being incomplete, very slow, and low in magnitude.
Complete changes between color morphs were obtained for adult Heterostichus in
field color change experiments, however. The only successful changes to red morphs
were obtained with females in situ, indicating that some factor not present in the
laboratory live plant experiments is involved. Additionally, complete ( + + + ) adult
changes were only obtained in situ, and then, only with females. Neither Wilkie (1966)
nor Burgess (1976, 1978) conducted in situ color change experiments. Adult males,
corresponding to collection frequency results (Stepien, 1986a), gamed some green
tunaxanthin pigment on green backgrounds, but did not become bright green morphs,
remaining olive brown-green in color.
Since in situ cages were suspended 30 m up from the seafloor (in order to avoid
attacks by crustacean zooplankton on adult fish), influx of crustacean food from
surrounding plant habitats was possibly lessened (in comparison with experiments on
the seafloor). Cage experiments on the seafloor were conducted successfully for
juveniles only and results of these experiments in comparison with juvenile experiments
in suspended cages appeared identical. Kelpfish in all in situ experiments were not fed,
observations and gut content analyses indicating that they primarily ate small fishes that
206
CAROL A. STEPIEN
swam through the cages. It was observed that the cages (both when suspended and on
the seafloor) attracted many fishes, including kelp&h. In fact, when one suspended cage
was pulled up, two uncaged Het~ro~~c~~ were collected that had been “resting” on top
of the cage.
Fishes and larger crustaceans consumed* such as the kelp crab ~~~e~~~ prodmu
Randall, did not noticeably vary in color between habitats. Diet of adult kelpfish, relying
less upon cryptically-colored epiphytic crustaceans, did not appear to vary signiIicantly
between color morphs. Red females were fluently found in small patches of red algae,
located near green or brown algae. Most kelpfish found in matching plants were also
located in close proximity to plants of other colors. Additionally, adult kelpfish often
were observed to forage away from matching colors of plants, indicating that dietary
differences may play little role in detesting
color morphs.
In conclusion, these experiments indicate that kelpfish color morphs are regulated by
background color. Juvenile kelp&h assumed the brown br green color of surrounding
plant habitats, changing color morph completely within 1 to 2 wk. Upon reaching sexual
maturity, adult males apparently lost their ability to become true green, although some
retained a limited capability to become olive green-brown. This color is apparently
produced by deposition of some tunaxanthin, along with astaxanthin and c~tb~~thin
(Stepien, 1985). The majority of adult females appeared to readily change from
depositing one type primary ~te~ent~
x~~ophyll to another. Color changes in
adult kelpfish occurred more slowly than those of juveniles, which may reflect metabolic
and/or hormonal differences. The influence of dietary epiphytic crustaceans on color
morphic changes is currently being tested.
Ability to change color may allow females to change habitats, utilizing plant colors
on a space-available basis, while retaining the advantages of crypsis. Field observations
indicated that kelpfish are very abundant, territorial, and evenly-spaced in favorable
areas. Habitats occupied by females differed from those of males in color, species, and
depth distributions (Stepien, 1986a).
The trimorphic patterns of female kelpfish may be an adaptation for establish~g
territories in non-male habitats, thereby avoiding territorial competition with male
nest-guarding sites (Stepien, 1986a). In the present study, red algae were observed to
be more plentiful in spring and summer seasons following severe winter storms (1978
and 1983). Storms and the El Nina weather conditions of 1982 to 1983 resulted in
widespread destruction of giant kelp (~~c~~c.~~r~~~~~~~~)in collection sites on Santa
Catalina Isfand. Dayton et&. (1984) and Ebeling et&. (1985) found that storm
disturbances altered pfant species compositions in California kelp forest communities.
Color change flexibility of female kelpfish may allow them to alter color morph
frequencies within populations, adjusting to changes in available plant habitat colors
with seasonal variations and storm disturbances.
REGULATION OF KELPFISH COLOR PATTERNS
207
ACKNOWLEDGEMENTS
Grants and funds supporting this research were generously provided by Sigma Xi,
the Lerner Fund for Marine Sciences, the Theodore Roosevelt Memorial Scholarship
Fund (American Museum of Natural History), the University of Southern California
Biology Department, and a California Sea Grant Traineeship. I greatly appreciate the
research laboratory facilities which were provided gratis by the Catalina Marine Science
Center and University of Southern California’s Institute for Marine and Coastal
Studies’ Fish Harbor Research Laboratory. Southern California Edison and Lawler,
Matusky, and Skelley (L.M.S.) Engineering Company provided laboratory facilities,
assistance, and personnel in Redondo Beach for the 1980 rearing study.
I thank the following individuals for their assistance: S. Natfziger, C. Bostick,
D. Wilkie, C. Winkler, L. Craft, N. Jones, R. Moore, R. Wright, B. Kulik, J. Sudick,
L. Allen, M. Carr, R. Provin, D. Perry, S. Azen, B. Nafpaktitis, R. Brusca, G. Bakus,
and B. Abbott.
REFERENCES
ASTM, 1974. Standard method for visual evaluation of color differences of opaque materials. No.
D 1729-69. ASTM, Philadelphia, 6 pp.
ASTM, 1980. Standard method of specifying color by the Munsell system. No. D 1535-80. ASTM,
Philadelphia, 23 pp.
BAGNARA, J.T. & M. E. HADLEY,1973. Chromatophores and color change: a comparativephysiologv of animal
pigmentation. Prentice-Hall, Inc., N.J., 202 pp.
BRITTEN,G., 1983. The biochemistry of naturalpigments. Cambridge University Press, London, 336 pp.
BROWN,F.A., 1973. Chromatophores and color change. In, Comparative animalphysiology, edited by C. L.
Prosser, W.B. Saunders Co., Philadelphia, 3rd edition, pp. 915-950.
BURGESS,T. J., 1976. Seasonal intertidal distribution, high tide movements, substrate preferences, and color
change capabilities of red and green colormorphs of Xererpesfucorum (Family: Pholidae), an intertidal
fish from central California. Master’s thesis, California State University, Fullerton, 114 pp.
BURGESS,T. J., 1978. The comparative ecology of two sympatric polychromatic populations of Xererpes
fucorum Jordan & Gilbert (Pisces : Pholidae) from the rocky intertidal zone of central California. J. Exp.
Mar. Biol. Ecol., Vol. 35, pp. 43-58.
COYER,J.A., 1979. The invertebrate assemblage associated with Macrocystispyriferu and its utilization as
a food resource by kelp forest fishes. Ph.D. dissertation, University of Southern California, Los Angeles,
314 pp.
CROZIER,G. F. & D. W. WILKIE, 1966. Occurrence of a dihydroxy c-carotene in a fish. Comp. Biochem.
Physiol., Vol. 18, pp. 80 l-804.
DAVIES,B. H., W.-J. HSU & C.O. CHICHESTER,1965. The metabolism of carotenoids in the brine shrimp
Artemia salina. Biochem. J., Vol. 94, p. 26.
DAVIES, B. H., W.-J. Hsu & C. 0. CHICHESTER,1970. The mechanism of conversion of B-carotene into
canthaxanthin by the brine shrimp, Arfemia salina L. (Crustacea : Branchiopoda). Camp. Biochem.
Physiol., Vol. 33, pp. 601-615.
DAYTON,P. K., V. CURRIE,T. GERRODETTE,B.D. KELLER,R. ROSENTHAL& D. VEN TRESCA,1984. Patch
dynamics and stability of some California kelp communities. Ecol. Monogr., Vol. 54, pp. 253-289.
EBELING,A. W., D. R. LAUR& R. J. ROWLEY,1985. Severe storm disturbances and reversal of community
structure in a southern California kelp forest. Mar. Biol., Vol. 84, pp. 287-294.
FEY, M. & S.P. MEYERS, 1980. Evaluation of carotenoid-fortified flake diets with the pearl gourami,
Trichogaster leeri. J. Aquaricult., Vol. 1, pp. 15-19.
208
CAROL
A. STEPIEN
and pigments. Ch. 6. In, Fish physiology. Vol. III, edited by W. S. Hoar &
D. J. Randall, Academic Press, New York, pp. 307-353.
GILCHRIST, B.M. &J. GREEN, 1960. The pigments ofArtemia. Proc. R. Sot., Ser. B, Vol. 152, pp. 118-136.
HATA,
M. & M. HATA, 1969. Carotenoid metabolism in Artemia salina. I. Comp. Biochem. Physiol., Vol. 29,
pp. 985-994.
HATA, M. & M. HATA, 1971. Carotenoid
pigments in goldfish (Carassius aura). I. Composition
and
distribution
of carotenoids.
Int. J. Biochem., Vol. 2, pp. 11-19.
HUBBS, C., 1952. A contribution
to the classification
of the blennioid fishes of the family Clinidae, with a
partial revision of the eastern Pacific forms. Stanford Ichth. Bull., Vol. 4, pp. 41-165.
KELLY, K.L. & D.B. JUDD, 1976. Color: universal dictionary of names. U.S. Department
of Commerce,
Washington,
D.C., 83 pp.
LEE, W.L., 1966. Color change and the ecology of the marine isopod Idotea (Pentidotea) montereyensis
Maloney, 1933. Ecology, Vol. 47, pp. 930-941.
LEE, W. L., 1972. Chromatophores
and their role in color change in the marine isopod Idotea montereyensis
(Maloney). J. Exp. Mar. Biol. Ecol., Vol. 8, pp. 201-215.
MUNSELL, A. H., 1946. A color notation. Munsell Co., Baltimore, 74 pp.
MIJNSELL COLOR Co., 1969. Munsell book of color, neighboring hues edition, mattefinish collection. Munsell
Color Co., Baltimore.
MUNSELL COLOR Co., 1976. Munsell book of color, pocket edition. Munsell Color Co., Baltimore.
NELSON, J. S., 1984. Fishes of the world. John Wiley & Sons, N.Y., 416 pp.
OKADA, Y. K., 1962. Sex reversal in the Japanese wrasse Halichoerespoecilopterus. Proc. Jpn. Acad., Vol. 38,
pp. 508-513.
OKADA, Y. K., 1964. Effect of androgen and estrogen in sex reversal in the wrasse Halichoerespoecilopterus.
Proc. Jpn. Acad., Vol. 40, pp. 541-544.
PARKER, G. H., 1948. Animal colour changes and their neurohumours. Cambridge University Press, London,
373 pp.
PARKER, G.H. & A. ROSENBLUETH, 1941. The electric stimulation of the concentrating
(adrenergic)
and
the dispersing (choline@)
nerve-fibres of the melanophores
in the cattish. Proc. Natl. Acad. Sci. U.S.A.,
Vol. 31, pp. l-8.
QUAST, J.C., 1968. Observations
on the food of the kelp-bed fishes. In, Utilizationof kelp-bed resources in
southern California, edited by W. J. North & C. L. Hubbs. Calif Fish. Bull., Vol. 139, pp. 109-142.
ROEDE, M. J., 1972. Color as related to size, sex, and behavior in seven Caribbean labrid fish species (genera
Thalasomma, Halichoeres, Hemipteronotus). Studies on the fauna of Curacao and other Caribbean Islands.
Vol. 42, pp. l-264.
SIEGEL, S., 1956. Nonparametric statisticsfor the behavioral sciences. McGraw-Hill,
N.Y., 312 pp.
SOKAI., R. R. & F. J. ROHLF, 1981. Biometry: the principle and practice of statistics in biological research,
W. H. Freeman & Co., San Francisco, second edition, 859 pp.
STEPIEN, C. A., 1985. Life history, ecology, and regulation of color morphic patterns of the giant kelp&h,
Heterostichus rostratus Girard (Family Clinidae). Ph.D. dissertation,
University of Southern California,
Los Angeles, 318 pp.
STEPIEN, CA., 1986a. Color pattern and habitat differences between male, female, and juvenile giant
kelptish, Heterostichus rostratus Girard. Bull. Mar. Sci., in press.
STEPIEN, C. A., 1986b. Life history and larval development
of the giant kelpfish, Heterostichus rostratus
Girard (family Clinidae). Fish. Bull. NOAA, Vol. 84 (In press).
STEPIEN,CA. & R.C. BRUSCA, 1985. Nocturnal
attacks on nearshore fishes by crustacean zooplankton.
Mar. Ecol. Prog. Ser., Vol. 25, pp. 91-105.
STOLL, L. M., 1955. Hormonal control of the sexually dimorphic pigmentation
of Thalassoma bifasciatum.
Zoologica, Vol. 40, pp. 125-132.
VON FRISCH, K., 1911. Beitrage zur Physiologie der Pigmentzellen in der Fischhaut. Arch. Gesamt. Physiol.,
Vol. 138, pp. 319-387. (In German).
WARING, H., 1963. Color change mechanisms of cold-blooded vertebrates. Academic Press, N.Y., 227 pp.
WILKIE, D. W., 1966. Colour pigments in the penpoint gunnel Apodichthys jlavidus and their ecological
significance. Master’s thesis, University of British Columbia, 143 pp.
FUJII, R., 1969. Chromatophores