Physiology of infected Batallaria
J. Miller Pg 2
ABSTRACT: The effects of larval trematode infection on the
thermal resistance, respiration rate, rate of Ulva sp. con-
sumption and gamete production of Batallaria attramentaria
were determined. Nonparasitized snails showed a greater
survival rate at 46°0 for 1 hour (.1)p2.05) and at 46°0 for
1 hours (p£.05). The average respiration rates of infected
and noninfected snails did not differ significantly. In-
dividual respiration rates varied widely in both parasitized
and nonparasitized snails. Infected snails consumed more
Ulva sp. than uninfected snails (pK.06). No eggs or sperm
were observed in heavily infected snails.
J. Miller Pg 3
Physiology of infected Batallaria
INTRODUCTION
Because the host-parasite relationship between molluscs
and helminths is longstanding and widespread, (Lauckner, 1980)
ecological and physiological studies of the mollusc must con-
sider the effects of this parasitism on the host. Some of
these effects include cessation of sperm and egg production
(Cheng et al., 1965), alterations of digestive-enzyme activity
(Marshall et. al., 1974), reduced locomotor activity (Stam-
baugh and McDermot, 1969; Tallmark and Narrgren, 1976).
Gigantism (Rothschild, 1941), altered migratory habits
(Williams and Ellis, 1975), increased food consumption
(Wesenberg-Lund, 1934), lowered thermal resistance (Vernberg
and Vernberg, 1963) and altered respiration rates (Becker,
1964; Von Brand, 1947; and Vernberg and Vernberg, 1967) have
also been reported.
With future ecological studies in mind, this study was
undertaken to find out the effects of larval trematode in-
fection on the thermal resistance, respiration rate, rate of
Ulva sp. consumption, and gamete production of the marine mud-
flat snail Batallaria attramentaria.
MATERIALS AND METHODS
After a preliminary survey of larval trematode infection
levels in late April, 1980, 2.2 to 2.5 cm in length Batallaria
attramentaria were collected from Bennett's Slough, Monterey Bay,
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Physiology of infected Batallaria
California, in early May, 1980. Forty-seven per cent of the
snails within this population were parasitized with only one
undescribed cercaria. The snails were brought into the labo-
ratory and held in an aquarium containing mud and Ulva sp.
from the slough.
Effects of larval trematode infection on the thermal
resistance of Batallaria attramentaria were determined by
placing snails in individual 50 ml Erlenmyer flasks, which
contained 4 paper towel discs, moistened with 2 ml of sea
water. Each flask was stoppered with cotton and immersed
immediately in a temperature controlled water bath. Snail
viability was assayed by placing them, operculum side up,
into separate 30 ml beakers, covering them with sea water.
If the snail righted itself (i.e. operculum down) within
24 hours it was considered alive. Usually, both infected
and uninfected snails right themselves within a few hours
and often crawl out of the beakers. Then each snail was
dissected and checked for infection.
Respiration rates of the snails were measured with a
Gilson Differential Respirometer (Gilson Medical Electronics,
Middleton, WI.) at a shaking speed of 5 and a temperature of
1690. One snail was placed in each reaction vessel and just
covered with sea water. One half ml of 30% KOH was added to
the reaction vessel side arm to absorb C0, produced by the
snail. After rates were recorded, each snail was removed from
its shell, weighed, and checked for infection.
Physiology of infected Batallaria
J. Miller Pg 5
Effects of parasitism on food consumption were determined
by first cutting and weighing 6 cm x 6 cm pieces of Ulva sp.
collected from Bennett's slough. One snail, one square of
Ulva, and 40 ml of sea water were placed in each of 20, 9 cm
x 14 cm, disposable petri dishes. The petri dishes were kept
out of direct sunlight in 1 cm deep running sea water. After
10 days the Ulva was weighed and checked for infection.
Microscopic observations of the snail gonads were done
by preparing thin sections of 3 infected and 3 uninfected
snails. Tissues were fixed in a 5% glutaraldehyde, 9% formal-
dehyde solution, embedded in JB-4 plastic, cut into 2 u thick
sections and stained by the Periodic Acid Schiff method.
RESULTS
Thermal Resistance
The effects of larval trematode infection on Batallaria
attramentaria's resistance to thermal stress is shown in
Table I. No significant mortality differences were observed
at 39°C, 43°C, and 49°C. At 46°0 differences in survival
rates were significant at 1 hr (17p2.05) and at 14 hrs (p£.05).
After 2 hours at 46 C no differences in survival could be
detected. With a 3°0 increase, no snails of either popula-
tion survived a 30 minute exposure to 49' C.
Physiology of infected Batallaria
J. Miller Pg 6
Respiration Rate
The average respiration rate of infected snails does
not differ significantly from that of uninfected snails
(Table II). In both populations there was great variation
in individual respiration rates ranging from 24.96 to 122.85
ul O, consumed per gram of snail per hour. In the unin-
fected snails and from 38.3 to 121.32 ul 0» consumed per gram
of snail per hour in the infected snails.
Rate of Ulva sp. Consumption
Infected snails had a greater intake of Ulva than unin-
fected snails (p(.06) (Table III).
Microscopic Observations of Gonad
No eggs or sperm were observed in any of the sections
of heavily infected snails. Cercaria occupied the gonadal
tissue.
DISCUS!
SION
Infection by larval trematodes greatly affects the
physiology of Batallaria attramentaria, as shown by the
lowered resistance to thermal stress, increased food intake,
and lack of gametes in the infected snails. These results
concur with those reported by Vernberg and Vernberg (1962)
Physiology of infected Batallaria
J. Miller Pg 7
and Tallmark and Norrgren (1976) who found thermal resis-
tance to be less in other species of parasitized snails.
Wesenburg-Lund (1947) has previously shown that infected
snails ingest more food and James (1965) has reported
cessation of egg and sperm production in Littorina saxatilis.
The effect of parasitism on respiration still remains
unanswered. Similar average respiration rates for infected
and uninfected Batallaria at 16°0 may indicate that the
metabolic activity of the larval thermatode is similar to that
of the host tissue. With such a wide range of individual
rates, however, factors other than just parasitism must be
affecting respiration rates. Vernberg and Vernberg (1963)
reported differences in respiration rates of parasitized
and nonparasitized snails only at temperature extremes of
10°0 and 35°C; Van Brand and Files (1947) found no difference
in respiration rates at 30°0; and Beeker (1964) reported a
lower respiration rate for infected snails at 25°0.
Lower heat resistance, greater intake of food, and
absence of gametes in infected snails reduce their resistance
to environmental stress. The snail's individual reduced
fitness might not be noticeable under slough conditions,
but the fitness of the population may be reduced due to
parasitic castration. Whitlatch (1974) has reported estimates
for population sizes of Batallaria with no mention of the
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Physiology of infected Batallaria
effects parasitic castration has on population size. Further
studies should include work on the effects of infection on
Batallaria's fertility and population fluctuations of the
snail and parasite.
Physiology of infected Batallaria
J. Miller Pg 9
ACKNOWLEDGEMENTS
I'd like to thank all the faculty, staff, and students
for making spring at HMS a great experience. Special thanks
go to Dr. Gary Wagenbach for his patience, his guidance.
and an introduction to the Slough; to Dr. Robin Burnett for
pointing out the "significance" of my data; to Chris Patton
for spending most of his Mondays and more teaching me the fine
art of thin sectioning; and to Kathy French for filling all
the "Kathy I need this ...'
J. Miller Pg 10
Physiology of infected Batallaria
LITERATURE CITEI
BECKER, W. 1964. Der Einfluss von Trematoden auf den
Gastoffwechsel von Stagnicola palustris Mull. 2.
ParasiKde 25: 77-102.
CHENG, T. C., AND R. W. SNYDER. 1962. Studies on host¬
parasite relationships between larval trematodes and
their hosts. I. A review. II. The utilization of the
host's glycogen by the intramolluscan larvae of
Glypthelmins pennsylvaniensis Cheng, and associated
phenomena. Trans Am microsc Soc 81: 209-228.
CHENG, T. C., J. T. SULLIVAN, AND K. R. HARRIS. 1973.
Parasitic castration of the marine prosobranch gastropod
Nassarius obsoletus by sporocysts of Zoogonus rubellus:
histopathology. J Invertebr Path 21: 183-190.
LAUCKNER, G. 1980. Diseases of mollusca: gastropoda, pp.311-
400 in Otto Kimme, ed. Diseases of Marine Animals.
Pitman Press, Bath, Great Britain.
MARSHALL, I., D. P. MOMANUS, AND B. L. JAMES. 1974.
Phosphomonoesterase activity in intertidal prosobranchs
and in their digenean parasites. Comp Biochem Physiol
19 13: 301-306.
ROTHSCHILD, M. 1941. Observations on the growth and trematode
infections of Peringia ulvae in a pool in the Tamar
Saltings, Plymouth. Parasitology 33:406-415.
J. Miller Pg 11
Physiology of infected Batallaria
STAMBAUGH, J. E. AND J. J. MCDERMOT. 1969. The effects of
trematode larvae on the locomotion of naturally in-
fected Nassarius obsoletus. Proc Acad nat Sci Philad
43: 226-231.
TALLMARK, B. AND G. NORRGREN. 1976. The influence of para-
sitic thematodes on the ecology of Nassarius reticu-
latus in Gullmar Fjord. zoon 4: 149-156.
VERNBERG, W. B. AND F. J. VERNBERG. 1963. Influence of
parasitism on thermal resistance of the mud-flat snail,
Nassarius obsoletus Say. Expl Parasit 14: 330-332.
VERNBERG, W. B. AND F. J. VERNBERG. 1967. Interrelationships
between parasites and their hosts. III. Effect of
larval thematodes on the thermal metabolic response of
their mulluscan host. Expl Parasit 20: 225-231.
VON BRAND, T. AND V. S. FILES. 1947. Chemical and histolog-
ical observations on the influence of Schistosoma
mansoni infection on Australorbis glabratus. J Parasit
33: 476-82.
WESENBERG-LUND, C. 1934. Contributions to the development
of the Thematoda Digenea. Part II. The biology of the
freshwater cercariae in Danish freshwaters. K. danske
vidensk. Selsk. Skv. 3: 1-221.
WHITLATCH, ROBERT B. 1974. Studies on population ecology
of the salt marsh gastropod Batallaria zonalis. Veliger
17: 47-55.
Physiology of infected Batallaria
J. Miller Pg 12
WILLIAMS. I. C. AND C. ELLIS. 1975. Movements of the common
periwinkle, Littorina littorea, on the Yorkshire coast
in winter and the influence of infection with larval
Pigenea, J exp mar Biol Ecol 33: 413-432.
Physiology of infected Batallaria
J. Miller Pg 13
Table I: Survival of infected and uninfected Batallaria
attramentaria with respect to time and temperature.
% Surviving
Number of Snails
Infected Uninfected
Infected Uninfected
Temperature
—
39°C
100
10
100
6 hours
9 hours
92
12
13
43°
80
88
1 hour
92
2 hours
12
83
3 hours
46°
81
1 hour
41
1.5 hours
18
2 hours
22
3 hours
49°
17
5 hour
0
18
24
1 hour
Physiology of infected Batallaria
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Table II: Arithmetic means were calculated from pooled
oxygen consumption rates of infected and unin-
fected Batallaria attramentaria.
UN INFECTED
INFECTED
ul of O consumed
per gram of snail
76 + 25.3
70 + 23.6
per hour
(n=29)
(n=30)
Physiology of infected Batallaria
J. Miller Pg 15
Arithmetic means were calculated from pooled
Table III:
infected and uninfected Batallaria attramentaria
rates of Ulva sp. consumption.
UNINFECTED
INFECTED
grams of Ulva sp.
consumed
3.2 + 1.1
2.1 +1.3
per gram of snail
per 10 days
(n=10)
(n=10)