benthic filter feeders and grazers which in turn are consumed microbial and meiofaunal activity, general benthic trophic rela- by other community members. Thus, the large-scale current tionships, and recolonization. pattern is obviously important to the McMurdo Sound benthos. This work was supported by National Science Foundation Moreover, it appears that local variability in current intensity grant DPP 81-00189. may be responsible in part for the structure of benthic commu- nities. Those areas with high current speeds are expected to References have higher particle fluxes and lower sedimentation rates than nearby sluggish current sites, resulting in different faunal as- Barry, J.P. In preparation. Oceanographic patterns in McMurdo Sound, semblages. These physical processes may exert primary control Antarctica. over community productivity and are superimposed on the Barry, JR. and P.K. Dayton. Current patterns in McMurdo Sound, Antarctica and their relationship to local benthic communitites. Lw,- biotic interactions which have also been shown to be of impor- nology and Oceanography. tance in regulating benthic community structure (Dayton et al. Dayton, P.K., J.P. Barry, and C. Kooyman. In preparation. Deep water 1974). benthic faunal patterns under the Ross and McMurdo Ice Shelves, We intend to continue to investigate the relationship between Antarctica. physical processes and sub-ice benthic community structure. Dayton, P.K., and J.S. Oliver. 1977. Antarctic soft bottom benthos in The dramatic north-south and east-west gradients of productiv- oligotrophic and eutrophic environments. Science, 197, 55-58. ity and species composition in McMurdo Sound appear directly Dayton, P.K., G.A. Robilliard, R.T. Paine, and L.B. Dayton. 1974. Bio- related to ice cover and oceanographic features. As such, logical accomodation in the benthic community at McMurdo Sound, McMurdo Sound benthos are particularly amenable to testing Antarctica. Ecological Monographs, 44(1), 105-128. Dayton, P.K., D. Watson, A. Palmisano, J.P. Barry, J.S. Oliver, and D. hypotheses regarding the roles of in situ vs. advected primary Rivera. In press. Distribution patterns of benthic microalgal standing production, and/or the importance of biotic (competition, pre- stock at McMurdo Sound, Antarctica. Polar Biology. dation) vs. abiotic (current patterns, etc.) control of community Heath, R.A. 1977. Circulation across the ice shelf edge in McMurdo dynamics. We hope to investigate the importance of large- and Sound, Antarctica. In M.J. Dunbar (Ed.), Polar oceans. (Proceedings of local-scale current intensity on community production by coup- the Polar Ocean Conference.) ling current observations with growth rate and survivorship Lewis, EL., and R.G. Perkin. 1985. The winter oceanography of studies. In addition, we will continue and expand our benthic McMurdo Sound, Antarctica. In S. Jacobs (Ed.), Oceanology of the productivity studies (Dayton et al. in press) and hope to evalu- Antarctic Continental Shelf. (Antarctic Research Series vol. 43.) Wash- ate the roles of advected vs. in situ primary production on ington, D.C.: American Geophysical Union.

The timing of reproduction may be related closely to mode of Contrasting tempos of reproduction by reproduction. Animals with planktotrophic larvae, for exam- shallow-water ple, need to synchronize the production of larvae with periods when adequate food supply is available in the plankton. In animals in McMurdo Sound, Antarctica contrast, species that have lecithotrophic larvae or that bypass larval production altogether by brooding or encapsulating em- bryos and releasing juveniles may be uncoupled from periods J.S. PEARSE, I. BOSCH, J.B. MCCLINTOCK, of phytoplankton production; reproductive periods of such B. MARINOVIC, and R. BRITTON forms may be extended over much or all of the year. During our field work at McMurdo Station, from August 1984 Institute of Marine Sciences to January 1986, we were able to collect data on both the mode University of California and timing of many of the common, shallow-water inverte- Santa Cruz, California 95064 brates 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 re- Recent work by our group has revealed that a wide range of productive patterns have been described by other workers for reproductive modes prevails in McMurdo Sound, Antarctica, as six additional species of animals in the area, bringing the total in other parts of the world ocean (Pearse, Bosch, and McClin- number to 21 (table). tock 1986). The production of pelagic larvae is common, al- Seven of the species have planktotrophic larvae. Most of these though a large proportion of the larvae are lecithotrophic. species have discrete reproductive periods, spawning in late Among those species that have planktotrophic larvae, there is winter, spring, or early summer. Only the nemertean Parbolasia little evidence of starvation even when phytoplankton levels are corrugatus spawns with little or no seasonal pattern, and pil- very low (Olson, Bosch, and Pearse in press), probably because idium larvae were collected from the plankton throughout the such larvae are able to use dissolved organic material and to year. These larvae, as well as those of the asteroids and echi- feed on bacteria (Rivkin et al. 1986). Larval energy requirements noid, are able to at least supplement their diet with bacteria and are probably relatively low; energy stores in lecithotrophic lar- thereby not be directly dependent on the midsummer phy- vae, at least, function mainly to produce large juveniles and are toplankton bloom (Rivkin et al. 1986). The larvae of Euphausia little used during larval development (McClintock and Pearse crystallorophias, on the other hand, probably feed nearly ex- 1986). clusively on phytoplankton, and they are produced in syn-

182 ANTARCTIC 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 Evidencea

J F MA M J JASON D Pelagic embryos, planktotrophic larvae Polychete Flabelligera mundatab S S 2,3 Bivalve Limatula hodgsonib x x x x S S 2,4 Asteroids Odontaster validus S S S S 1a,2,3,4,5,7 Odontaster meridionalis S S S S 2,3,5 Porania antarctica S S S 2,5 Echinoid Sterechinus neumayeri x S x 1 b,2,3,4,5,6,7 Euphausid Euphausia crystal lorophias S x x SS ic Nemertean Parbolasia corrugatusb x x x x x x x x x x S S 1 d,2,6,7 Pelagic embryos, pelagic lecithotrophic larvae Copepod Euchaeta antarctica x SS x lc Cnidarian Edwardsia meridionalisb x x x x x x x x x x x x le Asteroids Acodontaster hodgsoni x x x x x x x x x x x x 2,3,5 Perknaster fuscusb x x x x x x x x x x x x 2,3 Benthic embryos, benithic lecithotrophic larvae Teleost Trematomous bernacchii S x x x S if Asteroid Porania sp. x x x x x x x x x x x x 2,5 Brooded embryos (no larvae) Peracardians Nototanais dimorphus x SS S S S S x 7 Orchomene plebs x SS S SS S ig Glyptonotus antarcticus x x x x x x x x x x x x lh Asteroid Diplasterias brucei x x x x x x x x x x x x ld,2,7 Echinoids Abatus nimrodi x x x x x x x x x x x 2,7 Abatus shackletoni x x x x x x x x x x x x 2,7 Bivalve Laternula elliptica 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 Dearborn, J.H. 1965a. Ecological and faunistic investigations of the marine 1964). bent hos at McMurdo Sound, Antarctica. (Doctoral dissertation, Stanford Most species with lecithotrophic larvae, whether benthic or University.) pelagic, as well as those that retain their embryos and bypass Dearborn, J.H. 1965b. Reproduction in the nototheniid fish Trematomus larval stages altogether, show little or no seasonal pattern of bernacchii Boulenger at McMurdo Sound, Antarctica. Copeia, 1965, reproduction. Nevertheless, the peracarideans Nototanais di- 302-308. morph us and Orchomene plebs reproduce seasonally; they spawn Dearborn, J.H. 1967. Food and reproduction of Glyptonotus antarcticus and begin brooding in late fall, winter, and spring, and the (Crustacea, Isopoda) at McMurdo Sound, Antarctica. Transactions of juveniles are released mainly in late spring and summer when the Royal Society of New Zealand, 18, 163-168. they can graze on the abundant diatoms (Marinovic and Pearse Littlepage, J.L. 1964. Seasonal variation in lipid content of two antarctic unpublished observations). The predaceous copepod Euchaeta marine crustacea. In R. Carrick, M. Holgate, and J. Prevost (Eds.), antarctica also has a restricted spawning season, producing Biologic Antarctique. Paris: Actualities Scientifiques et Industrielles, lecithothrophic pelagic larvae in midwinter that develop into Herman. juveniles capable of preying on the juvenile euphasiids present McClintock, J. B., and J. S. Pearse. 1986. Organic and energetic content of in the summer (Littlepage 1964). eggs and juveniles of antarctic echinoids and asteroids with The underlying cause of the restricted midsummer spawning lecithotrophic development. Comparative Biochemistry and Physiology, period of the fish Trematomus bernacchii remains unresolved. As 85A, 341-345. with E. antarctica, the juveniles could be dependent on the summer production of planktotrophic crustacean prey. The fall Oliver, J.S. 1979. Processes affecting the organization of marine soft-bottom communities in Monterey Bay, California and McMurdo Sound, Antarctica. spawning period of the bivalve Laternula elliptica, with its un- (Doctoral dissertation, University of California in San Diego.) usual mode of development (Pearse et al. 1986), is even more difficult to explain, but may correspond to a period of low Olson, R.R., I. Bosch, and J.S. Pearse. In press. The antarctic larval food predation on the embryos and juveniles. limitation hypothesis examined for the asteroid Odontaster validus. In conclusion, temporal patterns of reproduction by shallow- Limnology and Oceanography. water antarctic animals are variable and are only partly related Pearse, J.S. 1963. Marine reproductive periodicity in polar seas: A study to reproductive mode. As in other environments, reproductive on two invertebrates at McMurdo Station, Antarctica. Bulletin of the tempo is controlled by the specific requirements and con- Ecological Society of America, 44, 43. straints of particular species, and varies both among species in a Pearse, J.S. 1965. Reproductive periodicities in several contrasting pop- particular habitat and within species among different habitats. ulations of Odontaster validus Koehler, a common antarctic asteroid. While broad generalities can be made (e.g., species with feed- Antarctic Research Series, 5, 39-85. ing larvae tend to have restricted spawning times while those Pearse, J.S., and I. Bosch. In press. Are the feeding larvae of the without feeding larvae tend to reproduce throughout the year), commonest antarctic asteroid really demersal? Bulletin of Marine patterns for particular species, and their underlying causes, will Science. best be understood within the context of each species. Pearse, J.S. and A.C. Giese. 1966. Food, reproduction and organic We thank Kathy Ann Miller and Ann Shaffer for diving assist- constitution of the common antarctic echinoid Sterechinus neumayeri. ance, Vicki Pearse for comments on the manuscript, and the Biology Bulletin, 130, 387-401. Antarctic Services Inc. of ITT and the U.S. Naval Antarctic Sup- Pearse, J.S., I. Bosch, and J.B. McClintock. 1986. Contrasting modes of port Force for logistic support. This work was supported in part reproduction by common shallow-water antarctic invertebrates. Ant- by National Science Foundation grant DPP 83-17082. arctic Journal of the U.S., 20(5), 138-139. Rakusa-Suszeczewski, S. 1982. The biology and metabolism of Or- References choniene plebs (Hurley 1965)(Amphipoda: Gammaridea) from McMur- do Sound, Ross Sea, Antarctica. Polar Biology, 1, 47-54. Bosch, I., K. A. Beauchamp, M. E. Steele, and J. S. Pearse. In preparation. Development, metamorphosis, and seasonal abundance of embryos Rivkin, RB., I. Bosch, J.S. Pearse, and E.J. Lessard. 1986. Bacterivory: a and larvae of the antarctic sea urchin Sterechinus neumayer:. novel feeding mode for asteroid larvae. Science. 233, 1311-1314.

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