Biogeography and metabolism of phytoplankton and zooplankton in ...
percent of isolates from the sea water samples and 15 percent of those from fish guts. The remainder of the isolates from both groups appear to be a new species closely related to P fischeri, except for one isolate from each group that appears to be a totally new species or genus of luminous bacteria (Paul Baumann, personal communication). Phytoplankion. A basic antarctic question is how the growth rates of phytoplankton (the base of the food chain which supports the krill population) are controlled or limited by nutrients, light, and temperature. Holm-Hansen et at. (1977b) suggest that antarctic phytoplankton grow slowly (0.02-0.15 doublings per day) and that significant popula tions are active at low light intensities (less than 1 percent of the light intensity incident upon the sea surface). Aboard Glacier, also, our nitrogen-15 uptake measurements of samples from a Phaeocystis bloom near Ross Island showed that uptake of both nitrate and ammonium was very slow; the specific turnover time for both nitrate and ammonium was about 0.03 per day. In our previous work, we measured the attenuation of light in the water column using secchi disk readings. There may be an error in our calculated light flux in the lower portion of the euphotic zone for two reasons: (1) when working on a drifting icebreaker, the wire angle of the secchi disk sometimes approaches 45°, making estimation of the vertical distance difficult; and (2) we commonly deploy and recover the bottles in darkness; this was not possible when south of the Antarctic Circle, and the bottles were exposed to higher light during deployment and recovery. During the Glacier cruise we eliminated these problems by measuring the light flux using submersible Quantum Scalar Irradiance Meters (Booth, 1976). These were of two types: one automatically records the flux of photosynthetically active light quanta as a function of depth; the other has small units at the same depth as the bottles containing radiocarbon, which integrate the light flux during the entire incubation period. The biomass of phytoplankton in the water samples was estimated by measurement of adenosine triphosphate (Holm-Hansen and Booth, 1966). Our data on phytoplankton biomass and light attenuation in the water column, when combined with the radiocarbon and chlorophyll measurements by Texas A & M, will enable calculation of specific growth rates and quantum efficiency of the phytoplankton. The field party on Glacier consisted of 0. Holm-Hansen; E. Moussalli, R. J . Olson, and B. M. Tebo. We thank the U.S. Coast Guard for their help in these studies. The research was supported by National Science Foundation grant DPP 77-26394.
References
Booth, C. R 1976. The design and evaluation of a measurement system for photosynthetically active quantum scalar irradiance. Limnology and Oceanography, 21(2): 326-336. El-Sayed, S. Z., D. C. Biggs, D. Stockwell, R. Warner, and M. Meyer. 1978 Biogeography and metabolism of phytoplankton and zooplankton in the Ross Sea, Antarctica. Antarctic Journal of the Us., 13(4): 131-133. Holm-Hansen, 0., and C. R Booth. 1966. The measurement of adenosine triphosphate in the ocean and its ecological significance. Limnology and Oceanography, 11: 510-519. October 1978
Holm-Hansen, 0., F. Azam, A. F. Carlucci, It E. Hodson, and D. M. Karl. 1977a. Microbial distribution and activity in and around McMurdo Sound. Antarctic Journal of the Us., 12(4): 29-32. Holm-Hansen, 0., S. Z. El-Sayed, G. A. Franceschini, and It L. Cuhel. 1977b. Primary production and the factors controlling phytoplankton growth in the southern ocean. In: Adaptations Within Antarctic Ecosystems (Proceedings of the Third SCAR Symposium on Antarctic Biology, G. A. Llano, ed.). Gulf Publishing Co., Houston, Texas. pp. 11-50. Pomeroy, L. It, W.J. Wiebe, D. Frankenberg, C. Hendricks, and W. L. Layton. 1969. Metabolism of total water column. Antarctic Journal of the US., 5: 149-150. Sorokin, Yu. I. 1971. On the role of bacteria in the productivity of the tropical oceanic waters. Internationale Revue der Gesamten Hydrobiologie, 56: 1-48.
Biogeography and metabolism of phytoplankton and zooplankton in the Ross Sea, Antarctica S. Z. EL-SAYED, D. C. BIGGS, D. STOCKWELL, R. WARNER, and M. MEYER Department of Oceanography Texas A&M University College Station, Texas 77843
A cooperative study of the phytoolankton/ zooplankton/nutrient chemistry of the Ross Sea by Texas A&M University and Scripps Institute of Oceanography was conducted on the USCGC Glacier during December 1977-January 1978. Eighteen oceanographic stations between New Zealand and McMurdo Sound and off the Ross Ice Shelf were occupied (see map). The Texas A&M program focused on the biogeographical distribution, primary production, and metabolic activities of the phytoplankton and included an extension of the study of ice-algae we initiated in FebruaryMarch 1977 in the Weddell Sea (see El-Sayed and Taguchi, 1977). Special attention also was given to metabolic measurements of zooplankton oxygen utilization and ammonia excretion during this cruise and at Palmer Station. At the 18 stations occupied by Glacier, water samples were collected at eight depths corresponding to 100, 50, 25, 12, 6, 1, 0. 1, and 0.01 percent of incident light levels for estimation of concentrations of chlorophyll a, b, and c, phaeopigments, cell counts, and species composition of phytoplankton. Vertical net (35 micrometers) tows also were made for phytoplankton species composition. Size fractionation experiments were conducted to determine the percentage contribution of nannoplankton to primary production and phytoplankton standing crop. Primary production was determined by nine in situ experiments using the C14 (radioactive carbon) uptake method of Steemann Nielsen (1952). At all the stations, hydrocasts were made for determining temperature, salinity, dissolved oxygen, inorganic nutrients, hydrogen-ion concentration, and alkalinity. Zooplankton 131
160 170E 180 170W ' Wellington, 45S New Zealand
samples were collected at each station using twin 0.5-meter (333-micron mesh) nets (equipped with flow-meters) hauled vertically from 200 meters to the surface. The ice-algae were sampled using a coring device (7.5centimeter inner diameter) on loan from the Cold Regions Research Environmental Laboratories. Melted samples were taken for salinity and in vivo fluorescent determinations; subsamples were also preserved for floristic study. At each station, water samples were collected for determining dissolved nutrient concentrations (NO 3-1 NH4+, and SiO 4 4 ). To minimize contamination errors that could occur during sample storage, NH4+ was analyzed aboard ship. Preliminary analysis of the nutrient data showed conspicuously high NO 3 -, PO4-3, and SiO 4 4 concentrations south of the Polar Front, when compared with subantarctic waters. The stations in the pack ice showed a near-surface maximum of NO 3 -3, PO4-3, and SiO 4 4 compared with the open water stations, where the near-surface waters recorded minimal values. Ammonia also exhibited regional variability in surface waters. Relatively high concentrations of NH4+ (0.4-0.9 microgram-atom per liter) were found in the photic zone at subantarctic stations and immediately south of the Polar Front. Farther south, euphotic zone concentrations of NH4+ were generally low (less than 0.1-0.3 microgram-atom per liter; average = 0.1 p.g-at/liter), though distinct NH 4 maxima occurred in midwater. In particular, at the neritic stations where Phaeocystis was abundant (see below), NH4+ concentrations were less than 0. 1 p.g-atlliter to depths of 70 to 100 meters. At every station, the NH4+ maxima corresponded to the depth at which dissolved oxygen concentrations began to decrease significantly from surface values. The data are being analyzed to determine whether the NH4+ maxima and oxycline correspond to either a deep chlorophyll maximum or a nitrite maximum and zone of increased heterotrophic activity (see Kiefer et at., 1976; Packard et at., 1978).
Pacific Ocean
50
90'
55
South Americ
12
Africa Atlantic Ocean.
POLAR FRONT 65-
\
75S
tRA.....I,L12 l 4 160 170E 180 170W 160W 150W
Cruise Track of USCGC GLACIER December 1977- January 1978
Ammonium excretion and oxygen consumption by Ross Sea zooplankton (uscGc Glacier), December 1977—January 1978. NH4 + excretion 02 consumption O:NH4+ ratio (cg-at/g wet wt/h)a 102/g wet wt/h)b (by atoms) x±s(n) x±s(n) x±s(n)
Size (mg) x
Subantarctic ZOne:C Unsorted zooplankton 3.6 ± 2.1 (17) - Hyperiid amphipods 1.6 ± 0.3 (10) 340 ± 60(9) Euphausiids 2.6 ± 0.2 (3) 740 ± 70 (2) Calanoid copepods 5.3±0.8(3) 710±340(3) Gymnosome pteropods - 0.9(1)
- 19 ± 3 (9) 26 ± 1(2) 12±4(3) -
64 ± 20 26 ± 3 3±1 50
Antarctic zone:' Unsorted zooplankton 1.6± 1.0(17) Euphausiids:juvenile 0.9±0.4 (14) Euphausiids: adult 0.9 ± 0.3 (9) Euphausiids: all sizes 0.9 ± 0.3 (23) Calanoid copepods 1.3 ± 0.6 (17) Gammarid amphipods 0.8 ± 0.2 (3) Thecosome pteropods 1.6 ± 0.3 (4) Gymnosome pteropods 0.3 ± 0.1(2)
- 31 ± 16(13) 24 ± 13(6) 28 ± 15 (19) 15 ± 3 (7) 12 ± 2 (3) 16 ± 1 (4) 48 ± 3 (2)
10±2 90 ± 70 14 ± 5 18 ± 9 3±1 32 ± 20
- 240±80(13) 170 ± 30(6) 220 ± 70(19) 190 ± 40(7) 100 ± 30 (3) 280 ± 80 (4) 135 ± 35 (2)
'Microgram-atom per gram wet weight per hour. bM icroliters 02 per gram wet weight per hour. 'Stations I and 2 (temperature, 10 ± 2°C; 34 excretion experiments). dStat ions 3-18 (temperature, -1 ± 2°C; 66 excretion experiments).
132
ANTARCTIC JOURNAL
Extensive blooms of Phaeocystis (Haptophycea; Prymnesiales) were encountered off the Ross Ice Shelf at stations 10 through 15 (see map). The bloom extended from at least 167°E. to 164°W. and from 78°27'S. to about 76°S. At all stations in the area, Phaeocystis was so abundant that it clogged the zooplankton nets before they had filtered more than 30 cubic meters. Phaeocystis was not restricted to the 21-meter euphotic zone, but was present to depths of 100 to 150 meters. To determine the uptake of glycolic acid under naturally simulated conditions, uniformly labeled C14 glycolic acid was inoculated into subsamples for simulated and in situ incubation (Parsons et al., 1977). These experiments will be used to determine the fate of extracellular phytoplankton metabolites and a possible relation to heterotrophic bacterial biomass. Autoradiography will be used to identify the organisms involved in heterotrophic uptake of glycolic acid (Munro and Brock, 1968). Krill (Euphausia superba) were not common at stations occupied during this cruise, but a congeneric species of euphausiid (E. crystallorophio.$) was present at all stations south of the Polar Front and at subantarctic station 2. Except for numerous tiny larvaceans and chaetognaths, gelatinous zooplankton were rare. Hyperiid amphipods (primarily Parathemisto) were abundant at the subantarctic stations, but in the Ross Sea species of gammarid amphipods predominated. Rates of oxygen consumption and NH 4 + excretion were measured at each station for individual organisms of the more abundant and larger sized zooplankton groups, in containers of filtered sea water (see table). Subantarctic species (stations 1 and 2) were used in 34 experiments and 66 experiments were conducted with species collected south of the Polar Front. As shown in the table, weight-specific NH 4 + excretion and oxygen consumption rates were uniformly higher at the stations north of the Polar Front than at the Ross Sea stations. However, ratios of atoms of oxygen consumed to atoms of NH 4 + excreted (O:NH 4 * ratios) were not significantly different (95 percent confidence level) between subantarctic and antarctic zooplankton. Gymnosome pteropods showed high O:NH 4 ratios, which reflect their very low rates of NH 4 + excretion (Biggs, 1977). O:NH 4 + ratios for other zooplankton averaged 12 to 31 (see table). This suggests that protein catabolism may account for 50 percent or more of zooplankton metabolism (Harris, 1959; Ikeda, 1974). Respiratory quotients measured by McWhinnie and others (1975, 1976) suggest that lipogenesis is quite significance, as well. Another Texas A&M research activity carried out during the 1977-78 austral summer was conducted by M. Meyer at Palmer Station, Anvers Island. Grazing experiments with krill (Euphausia superba) feeding on natural phytoplankton populations were conducted in cooperation with Mary Alice McWhinnie's krill study (see p. 133 in this issue). During each experiment, changes in cell number, dry weight, carbon, chlorophyll a, phaeopigments, oxygen, and ammonia were monitored. Preliminary analysis of these data suggest O:NH 4 + ratios of 19, which are comparable to the values measured for euphausiids from the Ross Sea cruise. Four additional krill grazing experiments were conducted to determine the ingestion rates of C14 labeled phytoplankton (Lasker, 1966), which were isolated and cultured at Palmer Station. The antarctic phytoplankton cultures will be continued at Texas A&M University for taxonomic and physiological studies. October 1978
References
Biggs, D. C. 1977. Respiration and ammonium excretion by open ocean gelatinous zooplankton. Limnology and Oceanography, 22: 108-117. El-Sayed, S. Z., and S. Taguchi. 1977. Phytoplankton studies in the water column and in the pack ice of the Weddell Sea. Antarctic Journal of the Us., 12: 35-36. Harris, E. 1959. The nitrogen cycle in Long Island Sound. Bulletin of Bingham Oceanography, 17: 31-65. Ikeda, T. 1974. Nutritional ecology of marine zooplankton. Memoirs of the Faculty of Fisheries, Hokkaido University, 22: 1-97. Kiefer, D. A., RJ. Olson, and 0. Holm-Hansen. 1976. Another look at the nitrite and chlorophyll maxima in the central North Pacific. Deep Sea Research, 23: 1199-1208. Lasker, R 1966. Feeding, growth, respiration and carbon utilization of a Euphausiid crustacean. Journal of Fisheries Research Board, Canada, 23: 1291-1317. McWhinnie, M. A., and C. J. Denys. 1978. Biological studies of Antarctic krill, austral summer, 1977-1978. Antarctic Journal of the US., 13(4): 133-135. McWhinnie, M. A., C.J. Denys, and D. Schenborn. 1976. Biology of krill (Euphausia superba) and other antarctic invertebrates. Antarctic Journal of the US., 11: 55-58. McWhinnie, M. A., S. Rakusa-Suszczewski, and M. 0. Cahoon. 1975. Physiological and metabolic studies of antarctic fauna, austral 1974 winter at McMurdo station. Antarctic Journal of the US., 10: 293-297. Munro, A. L. A., and T. D. Brock. 1968. Distribution between bacterial and algal utilization of soluble substances in the sea.Journal of General Microbiology, 51: 35-42. Packard, T. T., R. C. Dugdale,J.J. Goering, and R. T. Barber. 1978. Nitrate reductase activity in the subsurface waters of the Peru Current.Journal of Marine Research, 36: 59-76. Parsons, R. T., M. Takahashi, and B. Hargrave. 1977. Biological Oceanographic Processes (2nd ed.). Pergamon Press, New York. Steemann Nielsen, E. 1952. The use of radioactive carbon (C14) for measuring organic production in the sea.Journal du Conseil, Conseil International pour l'Exploration de la Mer, 18: 117-140.
Biological studies of antarctic krill, austral summer, 1977-1978 M. A. MCWHINNIE and C.J. DENYS Department of Biological Sciences De Paul University Chicago, Illinois 60614
Our study of the biology of krill, Euphausia superba, continued at Palmer Station from 4 December 1977 to 28 March 1978. Two new krill laboratories provided the first opportunity to maintain large stocks of living planktonic animals over long periods (see figure 1). These wet-laboratories are 133
References
Booth, C. R 1976. The design and evaluation of a measurement system for photosynthetically active quantum scalar irradiance. Limnology and Oceanography, 21(2): 326-336. El-Sayed, S. Z., D. C. Biggs, D. Stockwell, R. Warner, and M. Meyer. 1978 Biogeography and metabolism of phytoplankton and zooplankton in the Ross Sea, Antarctica. Antarctic Journal of the Us., 13(4): 131-133. Holm-Hansen, 0., and C. R Booth. 1966. The measurement of adenosine triphosphate in the ocean and its ecological significance. Limnology and Oceanography, 11: 510-519. October 1978
Holm-Hansen, 0., F. Azam, A. F. Carlucci, It E. Hodson, and D. M. Karl. 1977a. Microbial distribution and activity in and around McMurdo Sound. Antarctic Journal of the Us., 12(4): 29-32. Holm-Hansen, 0., S. Z. El-Sayed, G. A. Franceschini, and It L. Cuhel. 1977b. Primary production and the factors controlling phytoplankton growth in the southern ocean. In: Adaptations Within Antarctic Ecosystems (Proceedings of the Third SCAR Symposium on Antarctic Biology, G. A. Llano, ed.). Gulf Publishing Co., Houston, Texas. pp. 11-50. Pomeroy, L. It, W.J. Wiebe, D. Frankenberg, C. Hendricks, and W. L. Layton. 1969. Metabolism of total water column. Antarctic Journal of the US., 5: 149-150. Sorokin, Yu. I. 1971. On the role of bacteria in the productivity of the tropical oceanic waters. Internationale Revue der Gesamten Hydrobiologie, 56: 1-48.
Biogeography and metabolism of phytoplankton and zooplankton in the Ross Sea, Antarctica S. Z. EL-SAYED, D. C. BIGGS, D. STOCKWELL, R. WARNER, and M. MEYER Department of Oceanography Texas A&M University College Station, Texas 77843
A cooperative study of the phytoolankton/ zooplankton/nutrient chemistry of the Ross Sea by Texas A&M University and Scripps Institute of Oceanography was conducted on the USCGC Glacier during December 1977-January 1978. Eighteen oceanographic stations between New Zealand and McMurdo Sound and off the Ross Ice Shelf were occupied (see map). The Texas A&M program focused on the biogeographical distribution, primary production, and metabolic activities of the phytoplankton and included an extension of the study of ice-algae we initiated in FebruaryMarch 1977 in the Weddell Sea (see El-Sayed and Taguchi, 1977). Special attention also was given to metabolic measurements of zooplankton oxygen utilization and ammonia excretion during this cruise and at Palmer Station. At the 18 stations occupied by Glacier, water samples were collected at eight depths corresponding to 100, 50, 25, 12, 6, 1, 0. 1, and 0.01 percent of incident light levels for estimation of concentrations of chlorophyll a, b, and c, phaeopigments, cell counts, and species composition of phytoplankton. Vertical net (35 micrometers) tows also were made for phytoplankton species composition. Size fractionation experiments were conducted to determine the percentage contribution of nannoplankton to primary production and phytoplankton standing crop. Primary production was determined by nine in situ experiments using the C14 (radioactive carbon) uptake method of Steemann Nielsen (1952). At all the stations, hydrocasts were made for determining temperature, salinity, dissolved oxygen, inorganic nutrients, hydrogen-ion concentration, and alkalinity. Zooplankton 131
160 170E 180 170W ' Wellington, 45S New Zealand
samples were collected at each station using twin 0.5-meter (333-micron mesh) nets (equipped with flow-meters) hauled vertically from 200 meters to the surface. The ice-algae were sampled using a coring device (7.5centimeter inner diameter) on loan from the Cold Regions Research Environmental Laboratories. Melted samples were taken for salinity and in vivo fluorescent determinations; subsamples were also preserved for floristic study. At each station, water samples were collected for determining dissolved nutrient concentrations (NO 3-1 NH4+, and SiO 4 4 ). To minimize contamination errors that could occur during sample storage, NH4+ was analyzed aboard ship. Preliminary analysis of the nutrient data showed conspicuously high NO 3 -, PO4-3, and SiO 4 4 concentrations south of the Polar Front, when compared with subantarctic waters. The stations in the pack ice showed a near-surface maximum of NO 3 -3, PO4-3, and SiO 4 4 compared with the open water stations, where the near-surface waters recorded minimal values. Ammonia also exhibited regional variability in surface waters. Relatively high concentrations of NH4+ (0.4-0.9 microgram-atom per liter) were found in the photic zone at subantarctic stations and immediately south of the Polar Front. Farther south, euphotic zone concentrations of NH4+ were generally low (less than 0.1-0.3 microgram-atom per liter; average = 0.1 p.g-at/liter), though distinct NH 4 maxima occurred in midwater. In particular, at the neritic stations where Phaeocystis was abundant (see below), NH4+ concentrations were less than 0. 1 p.g-atlliter to depths of 70 to 100 meters. At every station, the NH4+ maxima corresponded to the depth at which dissolved oxygen concentrations began to decrease significantly from surface values. The data are being analyzed to determine whether the NH4+ maxima and oxycline correspond to either a deep chlorophyll maximum or a nitrite maximum and zone of increased heterotrophic activity (see Kiefer et at., 1976; Packard et at., 1978).
Pacific Ocean
50
90'
55
South Americ
12
Africa Atlantic Ocean.
POLAR FRONT 65-
\
75S
tRA.....I,L12 l 4 160 170E 180 170W 160W 150W
Cruise Track of USCGC GLACIER December 1977- January 1978
Ammonium excretion and oxygen consumption by Ross Sea zooplankton (uscGc Glacier), December 1977—January 1978. NH4 + excretion 02 consumption O:NH4+ ratio (cg-at/g wet wt/h)a 102/g wet wt/h)b (by atoms) x±s(n) x±s(n) x±s(n)
Size (mg) x
Subantarctic ZOne:C Unsorted zooplankton 3.6 ± 2.1 (17) - Hyperiid amphipods 1.6 ± 0.3 (10) 340 ± 60(9) Euphausiids 2.6 ± 0.2 (3) 740 ± 70 (2) Calanoid copepods 5.3±0.8(3) 710±340(3) Gymnosome pteropods - 0.9(1)
- 19 ± 3 (9) 26 ± 1(2) 12±4(3) -
64 ± 20 26 ± 3 3±1 50
Antarctic zone:' Unsorted zooplankton 1.6± 1.0(17) Euphausiids:juvenile 0.9±0.4 (14) Euphausiids: adult 0.9 ± 0.3 (9) Euphausiids: all sizes 0.9 ± 0.3 (23) Calanoid copepods 1.3 ± 0.6 (17) Gammarid amphipods 0.8 ± 0.2 (3) Thecosome pteropods 1.6 ± 0.3 (4) Gymnosome pteropods 0.3 ± 0.1(2)
- 31 ± 16(13) 24 ± 13(6) 28 ± 15 (19) 15 ± 3 (7) 12 ± 2 (3) 16 ± 1 (4) 48 ± 3 (2)
10±2 90 ± 70 14 ± 5 18 ± 9 3±1 32 ± 20
- 240±80(13) 170 ± 30(6) 220 ± 70(19) 190 ± 40(7) 100 ± 30 (3) 280 ± 80 (4) 135 ± 35 (2)
'Microgram-atom per gram wet weight per hour. bM icroliters 02 per gram wet weight per hour. 'Stations I and 2 (temperature, 10 ± 2°C; 34 excretion experiments). dStat ions 3-18 (temperature, -1 ± 2°C; 66 excretion experiments).
132
ANTARCTIC JOURNAL
Extensive blooms of Phaeocystis (Haptophycea; Prymnesiales) were encountered off the Ross Ice Shelf at stations 10 through 15 (see map). The bloom extended from at least 167°E. to 164°W. and from 78°27'S. to about 76°S. At all stations in the area, Phaeocystis was so abundant that it clogged the zooplankton nets before they had filtered more than 30 cubic meters. Phaeocystis was not restricted to the 21-meter euphotic zone, but was present to depths of 100 to 150 meters. To determine the uptake of glycolic acid under naturally simulated conditions, uniformly labeled C14 glycolic acid was inoculated into subsamples for simulated and in situ incubation (Parsons et al., 1977). These experiments will be used to determine the fate of extracellular phytoplankton metabolites and a possible relation to heterotrophic bacterial biomass. Autoradiography will be used to identify the organisms involved in heterotrophic uptake of glycolic acid (Munro and Brock, 1968). Krill (Euphausia superba) were not common at stations occupied during this cruise, but a congeneric species of euphausiid (E. crystallorophio.$) was present at all stations south of the Polar Front and at subantarctic station 2. Except for numerous tiny larvaceans and chaetognaths, gelatinous zooplankton were rare. Hyperiid amphipods (primarily Parathemisto) were abundant at the subantarctic stations, but in the Ross Sea species of gammarid amphipods predominated. Rates of oxygen consumption and NH 4 + excretion were measured at each station for individual organisms of the more abundant and larger sized zooplankton groups, in containers of filtered sea water (see table). Subantarctic species (stations 1 and 2) were used in 34 experiments and 66 experiments were conducted with species collected south of the Polar Front. As shown in the table, weight-specific NH 4 + excretion and oxygen consumption rates were uniformly higher at the stations north of the Polar Front than at the Ross Sea stations. However, ratios of atoms of oxygen consumed to atoms of NH 4 + excreted (O:NH 4 * ratios) were not significantly different (95 percent confidence level) between subantarctic and antarctic zooplankton. Gymnosome pteropods showed high O:NH 4 ratios, which reflect their very low rates of NH 4 + excretion (Biggs, 1977). O:NH 4 + ratios for other zooplankton averaged 12 to 31 (see table). This suggests that protein catabolism may account for 50 percent or more of zooplankton metabolism (Harris, 1959; Ikeda, 1974). Respiratory quotients measured by McWhinnie and others (1975, 1976) suggest that lipogenesis is quite significance, as well. Another Texas A&M research activity carried out during the 1977-78 austral summer was conducted by M. Meyer at Palmer Station, Anvers Island. Grazing experiments with krill (Euphausia superba) feeding on natural phytoplankton populations were conducted in cooperation with Mary Alice McWhinnie's krill study (see p. 133 in this issue). During each experiment, changes in cell number, dry weight, carbon, chlorophyll a, phaeopigments, oxygen, and ammonia were monitored. Preliminary analysis of these data suggest O:NH 4 + ratios of 19, which are comparable to the values measured for euphausiids from the Ross Sea cruise. Four additional krill grazing experiments were conducted to determine the ingestion rates of C14 labeled phytoplankton (Lasker, 1966), which were isolated and cultured at Palmer Station. The antarctic phytoplankton cultures will be continued at Texas A&M University for taxonomic and physiological studies. October 1978
References
Biggs, D. C. 1977. Respiration and ammonium excretion by open ocean gelatinous zooplankton. Limnology and Oceanography, 22: 108-117. El-Sayed, S. Z., and S. Taguchi. 1977. Phytoplankton studies in the water column and in the pack ice of the Weddell Sea. Antarctic Journal of the Us., 12: 35-36. Harris, E. 1959. The nitrogen cycle in Long Island Sound. Bulletin of Bingham Oceanography, 17: 31-65. Ikeda, T. 1974. Nutritional ecology of marine zooplankton. Memoirs of the Faculty of Fisheries, Hokkaido University, 22: 1-97. Kiefer, D. A., RJ. Olson, and 0. Holm-Hansen. 1976. Another look at the nitrite and chlorophyll maxima in the central North Pacific. Deep Sea Research, 23: 1199-1208. Lasker, R 1966. Feeding, growth, respiration and carbon utilization of a Euphausiid crustacean. Journal of Fisheries Research Board, Canada, 23: 1291-1317. McWhinnie, M. A., and C. J. Denys. 1978. Biological studies of Antarctic krill, austral summer, 1977-1978. Antarctic Journal of the US., 13(4): 133-135. McWhinnie, M. A., C.J. Denys, and D. Schenborn. 1976. Biology of krill (Euphausia superba) and other antarctic invertebrates. Antarctic Journal of the US., 11: 55-58. McWhinnie, M. A., S. Rakusa-Suszczewski, and M. 0. Cahoon. 1975. Physiological and metabolic studies of antarctic fauna, austral 1974 winter at McMurdo station. Antarctic Journal of the US., 10: 293-297. Munro, A. L. A., and T. D. Brock. 1968. Distribution between bacterial and algal utilization of soluble substances in the sea.Journal of General Microbiology, 51: 35-42. Packard, T. T., R. C. Dugdale,J.J. Goering, and R. T. Barber. 1978. Nitrate reductase activity in the subsurface waters of the Peru Current.Journal of Marine Research, 36: 59-76. Parsons, R. T., M. Takahashi, and B. Hargrave. 1977. Biological Oceanographic Processes (2nd ed.). Pergamon Press, New York. Steemann Nielsen, E. 1952. The use of radioactive carbon (C14) for measuring organic production in the sea.Journal du Conseil, Conseil International pour l'Exploration de la Mer, 18: 117-140.
Biological studies of antarctic krill, austral summer, 1977-1978 M. A. MCWHINNIE and C.J. DENYS Department of Biological Sciences De Paul University Chicago, Illinois 60614
Our study of the biology of krill, Euphausia superba, continued at Palmer Station from 4 December 1977 to 28 March 1978. Two new krill laboratories provided the first opportunity to maintain large stocks of living planktonic animals over long periods (see figure 1). These wet-laboratories are 133
