benthic filter feeders and grazers which in turn are consumed
by other community members. Thus, the large-scale current
pattern is obviously important to the McMurdo Sound benthos.
Moreover, it appears that local variability in current intensity
may be responsible in part for the structure of benthic communities. Those areas with high current speeds are expected to
have higher particle fluxes and lower sedimentation rates than
nearby sluggish current sites, resulting in different faunal assemblages. These physical processes may exert primary control
over community productivity and are superimposed on the
biotic interactions which have also been shown to be of importance in regulating benthic community structure (Dayton et al.
1974).
We intend to continue to investigate the relationship between
physical processes and sub-ice benthic community structure.
The dramatic north-south and east-west gradients of productivity and species composition in McMurdo Sound appear directly
related to ice cover and oceanographic features. As such,
McMurdo Sound benthos are particularly amenable to testing
hypotheses regarding the roles of in situ vs. advected primary
production, and/or the importance of biotic (competition, predation) vs. abiotic (current patterns, etc.) control of community
dynamics. We hope to investigate the importance of large- and
local-scale current intensity on community production by coupling current observations with growth rate and survivorship
studies. In addition, we will continue and expand our benthic
productivity studies (Dayton et al. in press) and hope to evaluate the roles of advected vs. in situ primary production on
Contrasting tempos of reproduction by
shallow-water
animals in McMurdo Sound, Antarctica
J.S. PEARSE, I. BOSCH, J.B. MCCLINTOCK,
B. MARINOVIC, and R. BRITTON
Institute of Marine Sciences
University of California
Santa Cruz, California 95064
Recent work by our group has revealed that a wide range of
reproductive modes prevails in McMurdo Sound, Antarctica, as
in other parts of the world ocean (Pearse, Bosch, and McClintock 1986). The production of pelagic larvae is common, although a large proportion of the larvae are lecithotrophic.
Among those species that have planktotrophic larvae, there is
little evidence of starvation even when phytoplankton levels are
very low (Olson, Bosch, and Pearse in press), probably because
such larvae are able to use dissolved organic material and to
feed on bacteria (Rivkin et al. 1986). Larval energy requirements
are probably relatively low; energy stores in lecithotrophic larvae, at least, function mainly to produce large juveniles and are
little used during larval development (McClintock and Pearse
1986).
182
microbial and meiofaunal activity, general benthic trophic relationships, and recolonization.
This work was supported by National Science Foundation
grant DPP 81-00189.
References
Barry, J.P. In preparation. Oceanographic patterns in McMurdo Sound,
Antarctica.
Barry, JR. and P.K. Dayton. Current patterns in McMurdo Sound,
Antarctica and their relationship to local benthic communitites. Lw,nology and Oceanography.
Dayton, P.K., J.P. Barry, and C. Kooyman. In preparation. Deep water
benthic faunal patterns under the Ross and McMurdo Ice Shelves,
Antarctica.
Dayton, P.K., and J.S. Oliver. 1977. Antarctic soft bottom benthos in
oligotrophic and eutrophic environments. Science, 197, 55-58.
Dayton, P.K., G.A. Robilliard, R.T. Paine, and L.B. Dayton. 1974. Biological accomodation in the benthic community at McMurdo Sound,
Antarctica. Ecological Monographs, 44(1), 105-128.
Dayton, P.K., D. Watson, A. Palmisano, J.P. Barry, J.S. Oliver, and D.
Rivera. In press. Distribution patterns of benthic microalgal standing
stock at McMurdo Sound, Antarctica. Polar Biology.
Heath, R.A. 1977. Circulation across the ice shelf edge in McMurdo
Sound, Antarctica. In M.J. Dunbar (Ed.), Polar oceans. (Proceedings of
the Polar Ocean Conference.)
Lewis, EL., and R.G. Perkin. 1985. The winter oceanography of
McMurdo Sound, Antarctica. In S. Jacobs (Ed.), Oceanology of the
Antarctic Continental Shelf. (Antarctic Research Series vol. 43.) Washington, D.C.: American Geophysical Union.
The timing of reproduction may be related closely to mode of
reproduction. Animals with planktotrophic larvae, for example, need to synchronize the production of larvae with periods
when adequate food supply is available in the plankton. In
contrast, species that have lecithotrophic larvae or that bypass
larval production altogether by brooding or encapsulating embryos and releasing juveniles may be uncoupled from periods
of phytoplankton production; reproductive periods of such
forms may be extended over much or all of the year.
During our field work at McMurdo Station, from August 1984
to January 1986, we were able to collect data on both the mode
and timing of many of the common, shallow-water invertebrates there. From preliminary analyses completed SO far, we
can estimate the temporal pattern of reproduction of 15 species
of common invertebrates in McMurdo Sound. Temporal reproductive patterns have been described by other workers for
six additional species of animals in the area, bringing the total
number to 21 (table).
Seven of the species have planktotrophic larvae. Most of these
species have discrete reproductive periods, spawning in late
winter, spring, or early summer. Only the nemertean Parbolasia
corrugatus spawns with little or no seasonal pattern, and pilidium larvae were collected from the plankton throughout the
year. These larvae, as well as those of the asteroids and echinoid, are able to at least supplement their diet with bacteria and
thereby not be directly dependent on the midsummer phytoplankton bloom (Rivkin et al. 1986). The larvae of Euphausia
crystallorophias, on the other hand, probably feed nearly exclusively on phytoplankton, and they are produced in synANTARCTIC JOURNAL
Months during the year when shallow-water benthic marine animals spawn in McMurdo Sound, Antarctica. (Symbols: S, main spawning
period; x, some spawning probable because mature gametes present, or in the case of suspected continuous breeders, brooding
animals and/or larvae found irregularly throughout the year.)
Months
Pelagic embryos,
planktotrophic larvae
Polychete
Flabelligera mundatab
Bivalve
Limatula hodgsonib
Asteroids
Odontaster validus
Odontaster meridionalis
Porania antarctica
Echinoid
Sterechinus neumayeri
Euphausid
Euphausia
crystal lorophias
Nemertean
Parbolasia corrugatusb
Evidencea
J F MA M J JASON D
S S
2,3
x x x x S S
2,4
S S S S
S S S S
S S S
S x
1a,2,3,4,5,7
2,3,5
2,5
x S x
1 b,2,3,4,5,6,7
x SS
ic
xxxxxxxxxx S S
1 d,2,6,7
Pelagic embryos,
pelagic lecithotrophic larvae
Copepod
Euchaeta antarctica
Cnidarian
Edwardsia meridionalisb
Asteroids
Acodontaster hodgsoni
Perknaster fuscusb
x SS x
lc
xxxxxxxxxxxx
le
xxxxxxxxxxxx
xxxxxxxxxxxx
2,3,5
2,3
S
if
Benthic embryos,
benithic lecithotrophic larvae
Teleost
Trematomous bernacchii
Asteroid
Porania sp.
Brooded embryos (no larvae)
Peracardians
Nototanais dimorphus
Orchomene plebs
Glyptonotus antarcticus
Asteroid
Diplasterias brucei
Echinoids
Abatus nimrodi
Abatus shackletoni
Bivalve
Laternula elliptica
x x x S
xxxxxxxxxxxx
2,5
x SS S S S S x
x
SS S SS S
xxxxxxxxxxxx
7
ig
lh
xxxxxxxxxxxx
ld,2,7
xxxxxxxxxxx
xxxxxxxxxxxx
2,7
2,7
x S x
2,4,5,6,7
a 1. Literature a. Pearse 1965, Pearse and Bosch in press; b. Pearse and Giese 1966, Bosch et all. in preparation; c. Littlepage 1964; d. Dearborn 1965a; e.
Oliver 1979; f. Dearborn 1965b; g. Pearse 1963, Rakusa-Suszeczewski 1982; h. Dearborn 1967.
2. Fresh gonadal smears.
3. Gonadal size analyses.
4. Histological analyses of the gonads.
5. pawned in the laboratory.
6. Spawning observed in the field.
7. Embryos or larvae collected in the field.
Developmental mode based on size and buoyancy of eggs and lack of observation of brooding; small eggs less than 200 micrometers planktotrophic;
large eggs more than 500 micrometers lecithotropic.
1986 REVIEW
183
chrony with the midsummer phytoplankton bloom (Littlepage
1964).
Most species with lecithotrophic larvae, whether benthic or
pelagic, as well as those that retain their embryos and bypass
larval stages altogether, show little or no seasonal pattern of
reproduction. Nevertheless, the peracarideans Nototanais dimorph us and Orchomene plebs reproduce seasonally; they spawn
and begin brooding in late fall, winter, and spring, and the
juveniles are released mainly in late spring and summer when
they can graze on the abundant diatoms (Marinovic and Pearse
unpublished observations). The predaceous copepod Euchaeta
antarctica also has a restricted spawning season, producing
lecithothrophic pelagic larvae in midwinter that develop into
juveniles capable of preying on the juvenile euphasiids present
in the summer (Littlepage 1964).
The underlying cause of the restricted midsummer spawning
period of the fish Trematomus bernacchii remains unresolved. As
with E. antarctica, the juveniles could be dependent on the
summer production of planktotrophic crustacean prey. The fall
spawning period of the bivalve Laternula elliptica, with its unusual mode of development (Pearse et al. 1986), is even more
difficult to explain, but may correspond to a period of low
predation on the embryos and juveniles.
In conclusion, temporal patterns of reproduction by shallowwater antarctic animals are variable and are only partly related
to reproductive mode. As in other environments, reproductive
tempo is controlled by the specific requirements and constraints of particular species, and varies both among species in a
particular habitat and within species among different habitats.
While broad generalities can be made (e.g., species with feeding larvae tend to have restricted spawning times while those
without feeding larvae tend to reproduce throughout the year),
patterns for particular species, and their underlying causes, will
best be understood within the context of each species.
We thank Kathy Ann Miller and Ann Shaffer for diving assistance, Vicki Pearse for comments on the manuscript, and the
Antarctic Services Inc. of ITT and the U.S. Naval Antarctic Support Force for logistic support. This work was supported in part
by National Science Foundation grant DPP 83-17082.
References
Bosch, I., K. A. Beauchamp, M. E. Steele, and J. S. Pearse. In preparation.
Development, metamorphosis, and seasonal abundance of embryos
and larvae of the antarctic sea urchin Sterechinus neumayer:.
184
Dearborn, J.H. 1965a. Ecological and faunistic investigations of the marine
bent hos at McMurdo Sound, Antarctica. (Doctoral dissertation, Stanford
University.)
Dearborn, J.H. 1965b. Reproduction in the nototheniid fish Trematomus
bernacchii Boulenger at McMurdo Sound, Antarctica. Copeia, 1965,
302-308.
Dearborn, J.H. 1967. Food and reproduction of Glyptonotus antarcticus
(Crustacea, Isopoda) at McMurdo Sound, Antarctica. Transactions of
the Royal Society of New Zealand, 18, 163-168.
Littlepage, J.L. 1964. Seasonal variation in lipid content of two antarctic
marine crustacea. In R. Carrick, M. Holgate, and J . Prevost (Eds.),
Biologic Antarctique. Paris: Actualities Scientifiques et Industrielles,
Herman.
McClintock, J. B., and J. S. Pearse. 1986. Organic and energetic content of
eggs and juveniles of antarctic echinoids and asteroids with
lecithotrophic development. Comparative Biochemistry and Physiology,
85A, 341-345.
Oliver, J.S. 1979. Processes affecting the organization of marine soft-bottom
communities in Monterey Bay, California and McMurdo Sound, Antarctica.
(Doctoral dissertation, University of California in San Diego.)
Olson, R.R., I. Bosch, and J.S. Pearse. In press. The antarctic larval food
limitation hypothesis examined for the asteroid Odontaster validus.
Limnology and Oceanography.
Pearse, J.S. 1963. Marine reproductive periodicity in polar seas: A study
on two invertebrates at McMurdo Station, Antarctica. Bulletin of the
Ecological Society of America, 44, 43.
Pearse, J.S. 1965. Reproductive periodicities in several contrasting populations of Odontaster validus Koehler, a common antarctic asteroid.
Antarctic Research Series, 5, 39-85.
Pearse, J.S., and I. Bosch. In press. Are the feeding larvae of the
commonest antarctic asteroid really demersal? Bulletin of Marine
Science.
Pearse, J.S. and A.C. Giese. 1966. Food, reproduction and organic
constitution of the common antarctic echinoid Sterechinus neumayeri.
Biology Bulletin, 130, 387-401.
Pearse, J.S., I. Bosch, and J.B. McClintock. 1986. Contrasting modes of
reproduction by common shallow-water antarctic invertebrates. Antarctic Journal of the U.S., 20(5), 138-139.
Rakusa-Suszeczewski, S. 1982. The biology and metabolism of Orchoniene plebs (Hurley 1965)(Amphipoda: Gammaridea) from McMurdo Sound, Ross Sea, Antarctica. Polar Biology, 1, 47-54.
Rivkin, RB., I. Bosch, J.S. Pearse, and E.J. Lessard. 1986. Bacterivory: a
novel feeding mode for asteroid larvae. Science. 233, 1311-1314.
ANTARCTIC JOURNAL