Ring, W. L.: Argulus borealis from Sanddabs
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Introduction:
Branchiurids, commonly called "Carp Lice or "Fish
Lice", are members of the class Crustacea. They superficially
resemble the Copepoda, but differ mainly in having a flattened
body; two large, movable compound eyes; an unsegmented,
limbless, bilobed abdomen; and four pairs of biramous thoracic
limbs. The mouth parts are characterized by a retractable,
poison spine in front of a moveable, cylinder-like proboscis,
The second maxillae are altered to form sucking disks which
enable branchiurids to cling to their hosts. With these
disks, they can move rapidly over the moist skin of a fish
with a scuttling, waddling motion (Fig. 1). They are all
wholly external parasites. Both sexes swim freely, actively,
and often. They are found on both fresh and salt water fish,
with a world wide distribution. (Cameron, 1956 and Noble
and Noble, 1964).
Branchiurids have a straight forward and well documented
life cycle. They have no egg sacs. Both sexes leave their
host at the breeding season. The eggs are laid in clusters
of 30 to 600 on a fixed, hard substratum and are fertilized
as laid by sperm obtained from a prior mating (Meehean, 1940
and Cameron, 1956). Eggs from salt-water species hatch
in four to six weeks, yielding advanced larvae, having
Ring, W. L.: Argulus borealis from Sanddabs
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four pairs of swimming legs. Although adult form is achieved
after the first molt, the larger specimens are often the
product of up to seven molts. The reproductive organs are
present at birth. Females tend to be slightly larger than
males. The reproductive cycle is run three times per year,
This means that the branchiurid must leave its host at least
three times a year (Tokioka, 1936).
Although there is a fairly extensive literature
available on species morphology (Martin, 1932; Meehean, 1940:
and Wilson, 1903,1944), development (Tokioka, 1936), and
incidence (Wilson, 1903 and Rizvi, 1969), there has been
very little work done on branchiurid behavior (Wilson, 1903
and Bower-Shore, 1940). Most studies have been on the
fresh-water species Argulus foliaceus. The family Argulidae
is economically signifant because it causes serious depredations
on fish populations in confined environments, fish hatcheries,
for example (Wilson, 1903 and Meehean, 1940).
This report describes some physiological stress parameters
and behavioral tropism of Argulus borealis in a free swimming
condition. Physiological stress studies were conducted in
normal, stagnant, and fresh water and in air. Tests were
run to determine the presence of geotropisms, heliotropisms,
and general free swimming behavior.
Ring, W. L.: Argulus borealis from Sanddabs
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Materials and Methods:
A. borealis were collected from the Pacific Sanddab,
Citharichtys sordidus. Identification was according to
Miller and Lea (1972). They were obtained by hook and line
bottom fishing in Monterey Bay, California about one mile
off Lover's Point at depths ranging from 150 ft. to 250 ft.
The fish were stored in a .34 m. deep, open air tank with
running sea water and were fed sliced squid.
All collections and observations were made between
April 15 and June 1, 1980 as part of 175H at Hopkins Marine
Station of Stanford University in Pacific Grove, California,
Branchiurids were removed from fish by placing them
in water, deep enough so that it lapped over the fish, but
shallow enough so that the gills were exposed and caused
distress and flapping by the fish. Branchiurids would almost
immediately leave the host and were then collected with a
syringe.
Branchiurids were tentatively identified as Argulus
borealis (Wilson, 1912), with the following discrepancies:
collected specimens possessed flagellated appendages and only
six rings on the ribs of the suckers, compared with hairless
appendages and nine rings on the ribs of the suckers.
Specimens were divided into three categories according to
size: less than .2 mm = small; .2 mm to 1 mm.- medium; and
larger than 1 mm = large.
Ring, W. L.: Argulus borealis from Sanddabs
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During experiments, death was defined as when the
body fluids stopped flowing inside the specimen. Temperature
was that of the sea water system, about 15° C., unless
otherwise noted. Room temperature was between 20° and
24° C. Water salinity was that of Monterey Bay, California.
Results and Discussion:
(1) Physiological stress studies--
Experiments were conducted to determine the physiological
stress parameters on A. borealis in a free swimming condition
to determine the factors affecting behavior. The survival
time in a free swimming condition in running and stagnant
sea water, in fresh water, and in air were studied,
(a) Longevity of A. borealis free swimming in sea water
Survival time of free swimming A. borealis was measured
as an index of the time limit for host finding, particularly
during the mating process.
Ring, W. L.: Argulus borealis from Sanddabs
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Branchiurids were placed in a bowl of salt water,
stagnant at room temperature, and in a steel wire mesh
box, 9 x 9 x 9 cm., and in a tank with fresh, running sea
water.
A. borealis survived for 4 days in the stagnant
salt water. A maximum survival time of 10 days was observed
in the running salt water (Fig. 2). In both stagnant and
running salt water the branchiurids attached to the sides
of the container more frequently as the experiment progressed.
Bower-Shore (1940) reported an average free-swimming
condition of 15 days for the fresh-water species A. foliaceus.
I conclude that A. borealis has up to 10 days to
find a new host after abandoning a previous host. This means
that within 10 days, branchiurids must leave their previous
host, mate, and find a new host.
(b) Survival of A. borealis in fresh water
A. borealis was studied in fresh water to review a
report in the literature of having the capacity to transfer
from salt to fresh water without problem,
Branchiurids were transferred directly from sea
water to fresh water. The water was not changed or renewed
and was kept at room temperature.
Ring, W. L.: Argulus borealis from Sanddabs
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No change in behavior was noted for the first hour,
but later branchiurids swam more slowly and finally died
within 15 hours (Fig. 3).
Wilson's 1903 studies of the salt water species A.
laticauda and A. Megalops from the Atlantic flat fish
Paralichtys reported that "they gave apparently no attention
to the change, but continued to swim about in the fresh
water as they had done in the salt." Bower-Shore (1940)
suggested that the freshwater species A. foliaceus could
not survive a rapid transition from fresh to salt water.
Wilson's study has been widely reported. Cameron (1956)
states, "Branchiurids can change from salt to fresh water
with ease.'
I conclude that A. borealis cannot survive transfer
from salt to fresh water. This finding contradicts the
results of Wilson. Possibly he did not run his experiments
long enough or different species may be more resistant.
(c) A. borealis survival time in air
The survival time of A. borealis in air was studied
to explain the host leaving behavior observed when the host
was placed in shallow water.
Ring, W. L.: Argulus borealis from Sanddabs
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Branchiurids were removed from the water, blotted,
and placed on a paper towel to soak up moisture, as described
by Bower-Shore (1940).
Branchiurids were immobile and under distress.
They were unable to support their main body structures.
Body surface appeared to be moist. Twitching occurred
for the first 5 min., afterwhich movement occurred only
when disturbed. No movement was observed after 25 min,
Death occurred in less than 1 hour. No change in body
coloration was noted. If the specimens were returned to
salt water after 10 min., death still occurred within a
few hours. (Fig. 4)
The fresh water species A. foliaceus had an average
survival period in excess of 15 hours and a rose coloration
at the time of death (Bower-Shore, 1940).
Branchiurids left their host when the fish was repeatly
and rapidly exposed to air and then water. If the fish
was completely exposed to air, the branchiurid was unable
to leave due to immobility in air. If the fish was not
exposed to enough air, the branchiurid found no motivation
to leave the host. In the field, this type of exposure
might well be interpretable by the branchiurid that dessication
in air was imminent, particularly as Sanddabs are bottom
Ring, W. L.: Argulus borealis from Sanddabs
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fish. Since branchiurids die so rapidly in air, it might
be better to risk the 10 day time limit for finding a new
host instead of the 15 min. time limit for returning to
the water from the air.
(2) Behavioral Studies-
The behavior of A. borealis in a free swimming condition
was studied in an attempt to understand the mechanisms used
in host finding.
All behavioral experiments were conducted in a glass
cylinder, 30 x 225 mm, which was divided by labeling into
8 equal areas. The cylinder was openable on one end and
always closed on the other end. Numbering was sequential,
When the cylinder was vertical, area l was always at the
top and area 8 was always at the bottom. Experiments consisted
of placing a branchiurid in the middle of the cylinder with
certain environmental variables controlled. After a 5 min.
wait, area position was recorded every second for 600 seconds.
Any time spent attached to the cylinder was not included in
the data.
(a) Random movement: a control study
Observations were first made to evaluate the possibility
that the experimental cylinder was effecting branchiurid behavior.
Ring, W. L.: Argulus borealis from Sanddabs
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The cylinder was placed horizontally. A plastic tent
was constructed around the experimental apparatus to decrease
the influence of environmental variables.
Resultant movement of the branchiurid was stastically
random (student "T" test, p-.0l; Fig. 5). Note that in
the graph, the means were almost the same for all areas. (Fig. 6)
This means that any non-random movement by the
branchiurid found in the experimentation using this apparatus
was not due to the cylinder.
(b) Geotropic responses in A. borealis
The effect of gravity on the free swimming branchiurid's
movement patterns was evaluated.
This was accomplished by placing the cylinder vertically.
Light and colors in the area of the cylinder were kept constant
by the plastic tent.
Branchiurids were observed to move towards the upper
regions. Movement may have been random (student "T" test.
p=.14).
Observations seem to suggest the presence of a negative
geotropic behavior. More experiments need to be run to
confirm this,
Ring, W. L.: Argulus borealis from Sanddabs
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(c) Heliotropic responses in A. borealis
Experiments were run to determine the effect of
light and dark colors on the free swimming branchiurid,
The cylinder was vertically oriented. Experiments
were run with a white top and a black bottom, with a black
top and a white bottom, with a white top and bottom, and
with a black top and bottom.
A white top with a black bottom caused the branchiurids
to collect within a few centimeters of the top. (student
"T" test, p-.01) A black top with a white bottom induced
the branchiurids to concentrate towards the bottom (student
"T" test, p-.01). A white top and bottom caused clumping
at the ends of the cylinder (student "T" test, p-.02).
A black top and bottom caused clumping in the middle (student
"T" test, p-.01; Fig. 7,8).
Bower-Shore (1940) reported a strong, negative heliotropism
in A. foliaceus. Possibly there is a seasonal variation
of just species differences between the two species.
Studies indicate the presence of a strong, positive
heliotropism in A. borealis.
Ring, W. L.: Argulus borealis from Sanddabs
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(d) Behavior of A. borealis in a current
Studies were made to determine the effect of water
movement on free swimming branchiurids.
Branchiurids were placed in a thin, long glass tube,
open on both ends. Water was pumped through the tube,
creating a current. The strength of the current was varied.
In the presence of a current, branchiurids always
oriented and swam against that current. Swimming speeds
of up to 1 ft. per 9 sec. or 400 ft. per hr. were achieved.
In strong currents, branchiurids would attach to the side
of the tube.
(e) Behavior of A. borealis with damaged eyes
Experiments were done to determine the functional
significance of the eyes to the free swimming behavior of
branchiurids.
Eyespots were destroyed by poking and teasing them
with a needle. Branchiurids were then returned to sea water.
Branchiurids made tight, rapid, continual flips which
continued until the first stages of death. In the presence
of a current, these flips would cease and counter-current
swimming would begin. No other tropisms were noted.
Heliotropism in A. borealis is dependent on intact
eyes. Counter-current swimming is not.
Ring, W. L.: Argulus borealis from Sanddabs
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(3) General discussion-
The behavioral repertoire for locating a bottom fish
host by a swimming parasite should include positive geotropism
and negative heliotropism, both of which would guide the
parasite to the bottom and thus to the host. This is just
the opposite of the experimental results which showed a
negative geotropism and a positive heliotropism. In a
behavioral repertoire for locating a high water column host,
these traits would be advantagous. In other words, it
appears as if the behavior of A. borealis is well suited
for a high water column fish parasite, but poorly adaptive
for a bottom fish parasite,
Rizvi (1969) noted a large seasonal fluctuation in
particular fish species infection rates. He theorized
that the infection rate in bottom fish would be highest
during the breeding season when the branchiurids went to
the bottom to lay eggs, and would then drop as branchiurids
returned to the higher water column fish for the rest of
the season. If this were indeed the case, it is possible
that my data was collected after the reproductive period
and that the branchiurids were leaving their bottom fish
host for those fish higher up. Thus the theoretical behavioral
traits would closely match experimental results.
Ring, W. L.: Argulus borealis from Sanddabs
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Pressure may have influenced the results. All experiments
were run at 1 atm., which contrasts sharply with the 6 or
7 atm. from which the branchiurids were collected. Possibly
the collected results are only applicable to the behavior
of A. borealis in the top of the water column where the
pressure is low.
These results only deepen the mystery of the host
finding method of A. borealis. More work is need to bring
light to this subject.
Ring, W. L.: Argulus borealis from Sanddabs
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Summary:
1. A. borealis in the free swimming condition does not
swim in a random fashion.
2. A. borealis exhibits a positive heliotropism in the
free swimming condition. This tropism is dependent
on intact eyes.
3.
A. borealis actively swims counter to currents. This
behavior occurs without intact eyes.
4. A. borealis exhibits a possible negative geotropism.
This behavior seem to rely on intact eyes.
5.
A. borealis can survive for up to 10 days in a free swimming
condition.
6. A. borealis cannot survive rapid, prolonged exposure
to fresh water.
7. A. borealis rapidly dies when exposed to air.
Ring, W. L.: Argulus borealis from Sanddabs
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Acknowledgments:
I would like to express my appreciation to the following people
for their assistance with this project: my primary advisor, Gary
Wagenbach; my secondary advisor, Donald P. Abbott; Norman D. Levine,
for his general amdable attitude; Alan Baldridge, for knowing where
to find everything; to Chuck Baxter and his Green Death; and finally
to Izzie Abbott, for being herself.
Ring, W. L.: Argulus borealis from Sanddabs
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Literature Cited:
Bower-Shore, Clifford. 1940. An Investigation of the Common
Fish Louse, Argulus Foliaceus. Parasitology. 32 (4):361-371.
Cameron, Thomas W. M. 1956. Parasites and Parasitism.
John Wiley & Sons, Inc., New York. pp 164-165,
Martin, M. F. 1932. On the Morphology and Classification
of Argulus. Proc. Zool. Soc. Lond. 11:771-806.
Meehean, 0. Lloyd. 1940. A Review of the Parasitic Crustacea
of the Genus Argulus in the Collections of the United
States National Museum. Proc. U. S. Nat. Mus. 88:459-527.
Miller, Daniel J. and Lea, Robert N. 1972. Guide to the
Coastal Fishes of California. Fish Bulletin 157.
California Department of Fish and Game.
Noble, Elmer R. and Noble, Glenn A. 1964. Parasitology,
the Biology of Animial Parasites. Lea & Rebiger, Philladephia.
pg 409.
Rizvi, S. S. H. 1969. Studies on the Structure of the
Sucker and Seasonal Incidence of Argulus foliaceus on
Some Fresh Water Fishes (Branchiura, Argulidae).
Crustaceana 17(2):200-206.
Ring, W. L.: Argulus borealis from Sanddabs
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Tokioka, Takasi. 1936. Larval Development and Metamorphosis
of Argulus japonicus. Mem. Col. Sci. Kyoto Imp. Univ.,
ser. B., 12:93-114.
Wilson, Charles Branch. 1903. North American Parasitic
Copepods of the Family Argulidae, with a Bibliography
of the Group and a Systematic Review of All Known Species.
Proc. U. S. Nat. Mus. 25:635-742.
1912. Parasitic Copepods from Nanaimo, British Columbia,
Including 8 Species New to Science. Contr. Can Biol..
1906-1910.
85-101.
1944. Parasitic Copepoda in the U. S. Natural Museum.
Proc. U. S. Nat. Mus. 94:20-34, 529-582.
Ring, W. L.: Argulus borealis from Sanddabs
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Figure Captions:
Fig. 1
Argulus japonicus, male, ventral view, from Meehean,
1940. pg. 462.
Fig. 2 Survival time of A. borealis in stagnant and running
sea water as a function of body size.
Fig. 3 Survival time of A. borealis in air as a function
of body size.
Fig. 4
Survival time of A. borealis after a direct transfer
from sea water to fresh water as a function of body
size.
Fig. 5 Movement of A. borealis in experimental cylinder,
flat and under constant light and color; time spent
in an area as a function of that area.
Fig. 6
Movement of A. borealis in a vertical cylinder with
constant light and color. 8 time spent in an area
as a function of that area.
Fig.
Movement of A. borealis in a cylinder with a white
top and a black bottom and a cylinder with a black
top and a white bottom. 8 time spent in an area as
a function of that area.
Ring, W. L.: Argulus borealis from Sanddabs
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Fig. 8 Movement of A. borealis in a cylinder with a white
top and bottom and in a cylinder with a black top
and bottom. 8 time spent in an area as a function
of that area.
Ring, W. L.: Argulus borealis from Sanddabs Fig. 1
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Ring, W. L.: Argulus borealis from Sanddabs
10
A stagnant
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6
43

2
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BODY SIZE
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Fig. 2
Ring, W. L.: Argulus borealis from Sanddabs
16
12
10
8
M
BODY SIZE
Fig. 3
Ring, W. L.: Argulus borealis from Sanddabs
40
M
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BODY SIZE
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Fig. 4
Ring, W. L.: Argulus borealis from Sanddabs
Sec.
N=15
160
T=600
120
80
40
12 3 4 5 6 7 8
Area
Fig. 5
90
70
50
30
%
10
A 90
70
50
30
10

N=6
T=600
Medium
1 2 3 4 5 6 7 8
N=6
T=600
Large
Area
Fig. 6
90
Dark
White
70
50
30
10—
1 2 3
4 5
7 8

90
White
Dark
A
70
50
30
10
Area
Fig.
90
70
50
30
90
70
50
30
10
0

—
2 3 4
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AREA
5 6 78

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white
white

Fig. 8