AMERIEZ 1988: Nano- and microplankton in the ice-edge zone ...
AMERIEZ 1988: Nano- and microplankton in the ice-edge zone during the austral winter DAVID
L. GARRISON, KURT R. BUCK,
and MARCIA M. COWING Institute of Marine Sciences University of California Santa Cruz, California 95064
During the Antarctic Marine Ecosystem Research in the IceEdge Zone (AMERIEZ) winter cruise (9 June to 5 July 1988), we sampled planktonic assemblages in the upper 100 meters of the water column along two transects across an ice-edge zone in the Weddell and Scotia seas region. (See cruise track in Ainley and Sullivan, Antarctic Journal, this issue.) Our samples were collected at four depths using either 10- or 30-liter Niskin sampling bottles. Whole-water samples were concentrated on Nuclepore filters and examined and counted using fluorescence microscopy (Booth 1987). Aliquots were also preserved in Lugol's iodine for counting with an inverted microscope (Reid 1983). Two 30-liter Niskin bottle samples were combined and these large volume samples were reduced to 500 milliliters by reverse-flow concentration (Garrison and Buck 1989). Cell dimensions were measured to calculate cell volumes and biomass was estimated from carbon: volume relationships (see Garrison and Buck 1989 for details). Plankton biomass ranged from 0.2 to 0.6 grams of carbon per square meter (figure 1). Heterotrophic biomass (flagellates plus ciliates) exceeded autotrophic biomass (diatoms plus flagellates) at most open water stations (see figure 1). The phytoplankton assemblage was comprised of dinoflagellates (an average of 57 percent of the autotrophic biomass), autotrophic nanoflagellates (30 percent) and diatoms (13 percent). The nanoplankton (cells less than 20 micrometers in equivalent spherical diameter) dominated in all groups except diatoms and comprised an average of 63 percent of the total autotrophic biomass. Autotrophic biomass increased from ice covered to open water stations (figures 1 and 2). Dinoflagellates (e.g., Gymnodinium spp. and Amphidinium spp.) dominated the heterotrophic biomass with other heterotrophic flagellates (choanoflagellates and heterotrophic nan-
158
oplankton) and ciliates (mostly nonloricate oligotrichs) occurring at similar levels and comprising a smaller fraction of the heterotrophic biomass. The biomass contribution of the larger, rarer protozoans is presented by Gowing et al. (Antarctic Journal, this issue). There was no obvious pattern to the vertical distribution of either heterotrophs or autotrophs in the upper 100 meters (figure 2). The biomass of protozooplankton during the winter cruise (see figure 1) was similar to that we measured at ice covered stations during the spring (AMERIEZ 83) and autumn (AMERIEZ 86) (Garrison and Buck 1989). The population structure of planktonic assemblages in antarctic waters is not well known, particularly during the austral winter. Although Balech and El-Sayed (1965) pointed out that dinoflagellates are abundant in antarctic waters and have apparently been overlooked by most workers, their predominance in both the autotrophic and heterotrophic fractions of the plankton was unexpected. The energy flow in the winter plankton-based food web has not been measured, but our population data suggest the importance of both autotrophic and heterotrophic nanoplankton during this season. This study was part of the Antarctic Marine Ecosystem Research at the Ice-Edge Zone (AMERIEZ) program and was supported by a National Science Foundation Grant to D.L. Garrison (DPP 84-20184). We thank Peter Jorgensen and the crew of Polar Duke for their whole-hearted support during the winter cruise.
References
Ainley, D.C., and C.W. Sullivan. 1989. A summary of a winter cruise of the Weddell and Scotia Seas on Polar Duke. Antarctic Journal of the U. S., 24(5). Balech, E., and S.Z. El-Sayed. 1965. Microplankton of the Weddell. (Antarctic Research Series, Vol. 5.) Washington, D.C.: American Geo-
physical Union. Booth, B.C. 1987. The use of autofluorescence for analyzing oceanic phytoplankton communities. Botanica Marina, 30, 101-108. Garrison, D.L., and K.R. Buck. 1989. Protozooplankton in the Weddell Sea, Antarctica: Abundance and distribution in the ice edge zone. Polar Biology, 9, 347-351.
Cowing, M.M., D.L. Garrison, K.R. Buck, and S.L. Coale. 1989. Winter protozooplankton from the Weddell and Scotia Seas. Antarctic Journal of the U.S.,, 24(5).
Reid, F.M.H. 1983. Biomass estimations of components of marine nanoplankton and picoplankton by the UtermOhl method. Journal of Plankton Research, 5, 235-251.
ANTARCTIC JOURNAL
Open Water
Ice
0.3
E o 0.2 I,
a E 0 iF3 0.1
7
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17
21
East Transact Stations (-40°W) Ice
Open Water
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E 0.2 o 01 0
E 0
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36 38 42 45 48 52 West Transact Stations (-48°W)
Heterotrophe Autotrophs Dinoflagellates - Dinoflagellatee M Flagellates Flagellates 20 Choanoflagellates Diatoms Ciliates
Figure 1. Biomass of nano- and microplankton integrated over the upper 100 meters along two transects across the ice-edge zone. See figure 1 in Ainley and Sullivan (Antarctic Journal, this issue) for station locations. Autotrophic and heterotrophic forms are shown as separate bars. See legend for composition of each trophic category. (gC .m 2 denotes grams of carbon per square meter.)
1989 REVIEW
159
Station 7
Station
Biomass (/Lgc.1-1) n
50 -c
0
0 1 2 3 01 I I I
O\
a)
100
Biomass (ag&1-1)
1 2 3
T /
21
.\
I
/o I 0 0 •'—'
50
-c
0 0
0 0) 0 100 0
0
O—OAutotrophs •—• Heterotrophs Figure 2. Vertical distributions of total autotrophic and heterotrophic biomass at a selected ice-covered station (station 7) and at a station from open water (station 21). (m denotes meter. pigC •1 1 denotes micrograms of carbon per liter.)
AMERIEZ 1988: Winter protozooplankton from the Weddell and Scotia Seas MARCIA M. GowiNc, DAVID L. GARRISON, KURT R. BUCK, and SUSAN L. COALE Institute of Marine Sciences University of California Santa Cruz, California 95064
As part of the Antarctic Marine Ecosystem Research at the Ice-Edge Zone (AMERIEZ) project, we are studying the distributions, abundances, and trophic ecology of heterotrophic protozooplankton. Protozooplankton range in size from microflagellates a few micrometers in length up to colonial radiolarians that can reach meters in size. In this report, we focus on protozooplankton ranging from 50 to 300 micrometers in their longest dimension. These include radiolarians, forami 160
niferans, heliozoans, and some ciliates. Samples were collected along several transects perpendicular to the ice edge during the AMERIEZ 88 cruise (see cruise track in Ainley and Sullivan, Antarctic Journal, this issue) in the austral winter from 9 June to 13 August 1988. We took both quantitative plankton tows and large-volume (60-liter) water samples; this report discusses preliminary results based on analysis of water samples from 8 of 17 stations. At each station, 30 liters of water were collected from each of 10 depths: 5 + 10 meters, 30 + 40 meters, 65 + 85 meters, 115 + 135 meters, and 190 + 210 meters. Samples from each pair of combined depths were concentrated to 200 milliliters by reverse-flow filtration (Garrison and Buck 1989) immediately after collection and preserved with Karnovsky's fixative (Garrison and Buck 1989). Upon return to our laboratory, samples were stained with the nuclear fluorochrome DAPI (Coleman 1980), concentrated in settling chambers, and examined with an inverted fluorescence microscope. The nuclear stain allowed us to distinguish between organisms that were alive at the time of capture and empty skeletons, and also indicated organisms that were undergoing reproduction. The nuclear stain was also useful for distinguishing organisms in samples with much detritus. ANTARCTIC JOURNAL
L. GARRISON, KURT R. BUCK,
and MARCIA M. COWING Institute of Marine Sciences University of California Santa Cruz, California 95064
During the Antarctic Marine Ecosystem Research in the IceEdge Zone (AMERIEZ) winter cruise (9 June to 5 July 1988), we sampled planktonic assemblages in the upper 100 meters of the water column along two transects across an ice-edge zone in the Weddell and Scotia seas region. (See cruise track in Ainley and Sullivan, Antarctic Journal, this issue.) Our samples were collected at four depths using either 10- or 30-liter Niskin sampling bottles. Whole-water samples were concentrated on Nuclepore filters and examined and counted using fluorescence microscopy (Booth 1987). Aliquots were also preserved in Lugol's iodine for counting with an inverted microscope (Reid 1983). Two 30-liter Niskin bottle samples were combined and these large volume samples were reduced to 500 milliliters by reverse-flow concentration (Garrison and Buck 1989). Cell dimensions were measured to calculate cell volumes and biomass was estimated from carbon: volume relationships (see Garrison and Buck 1989 for details). Plankton biomass ranged from 0.2 to 0.6 grams of carbon per square meter (figure 1). Heterotrophic biomass (flagellates plus ciliates) exceeded autotrophic biomass (diatoms plus flagellates) at most open water stations (see figure 1). The phytoplankton assemblage was comprised of dinoflagellates (an average of 57 percent of the autotrophic biomass), autotrophic nanoflagellates (30 percent) and diatoms (13 percent). The nanoplankton (cells less than 20 micrometers in equivalent spherical diameter) dominated in all groups except diatoms and comprised an average of 63 percent of the total autotrophic biomass. Autotrophic biomass increased from ice covered to open water stations (figures 1 and 2). Dinoflagellates (e.g., Gymnodinium spp. and Amphidinium spp.) dominated the heterotrophic biomass with other heterotrophic flagellates (choanoflagellates and heterotrophic nan-
158
oplankton) and ciliates (mostly nonloricate oligotrichs) occurring at similar levels and comprising a smaller fraction of the heterotrophic biomass. The biomass contribution of the larger, rarer protozoans is presented by Gowing et al. (Antarctic Journal, this issue). There was no obvious pattern to the vertical distribution of either heterotrophs or autotrophs in the upper 100 meters (figure 2). The biomass of protozooplankton during the winter cruise (see figure 1) was similar to that we measured at ice covered stations during the spring (AMERIEZ 83) and autumn (AMERIEZ 86) (Garrison and Buck 1989). The population structure of planktonic assemblages in antarctic waters is not well known, particularly during the austral winter. Although Balech and El-Sayed (1965) pointed out that dinoflagellates are abundant in antarctic waters and have apparently been overlooked by most workers, their predominance in both the autotrophic and heterotrophic fractions of the plankton was unexpected. The energy flow in the winter plankton-based food web has not been measured, but our population data suggest the importance of both autotrophic and heterotrophic nanoplankton during this season. This study was part of the Antarctic Marine Ecosystem Research at the Ice-Edge Zone (AMERIEZ) program and was supported by a National Science Foundation Grant to D.L. Garrison (DPP 84-20184). We thank Peter Jorgensen and the crew of Polar Duke for their whole-hearted support during the winter cruise.
References
Ainley, D.C., and C.W. Sullivan. 1989. A summary of a winter cruise of the Weddell and Scotia Seas on Polar Duke. Antarctic Journal of the U. S., 24(5). Balech, E., and S.Z. El-Sayed. 1965. Microplankton of the Weddell. (Antarctic Research Series, Vol. 5.) Washington, D.C.: American Geo-
physical Union. Booth, B.C. 1987. The use of autofluorescence for analyzing oceanic phytoplankton communities. Botanica Marina, 30, 101-108. Garrison, D.L., and K.R. Buck. 1989. Protozooplankton in the Weddell Sea, Antarctica: Abundance and distribution in the ice edge zone. Polar Biology, 9, 347-351.
Cowing, M.M., D.L. Garrison, K.R. Buck, and S.L. Coale. 1989. Winter protozooplankton from the Weddell and Scotia Seas. Antarctic Journal of the U.S.,, 24(5).
Reid, F.M.H. 1983. Biomass estimations of components of marine nanoplankton and picoplankton by the UtermOhl method. Journal of Plankton Research, 5, 235-251.
ANTARCTIC JOURNAL
Open Water
Ice
0.3
E o 0.2 I,
a E 0 iF3 0.1
7
14
17
21
East Transact Stations (-40°W) Ice
Open Water
0.3
E 0.2 o 01 0
E 0
0.1
36 38 42 45 48 52 West Transact Stations (-48°W)
Heterotrophe Autotrophs Dinoflagellates - Dinoflagellatee M Flagellates Flagellates 20 Choanoflagellates Diatoms Ciliates
Figure 1. Biomass of nano- and microplankton integrated over the upper 100 meters along two transects across the ice-edge zone. See figure 1 in Ainley and Sullivan (Antarctic Journal, this issue) for station locations. Autotrophic and heterotrophic forms are shown as separate bars. See legend for composition of each trophic category. (gC .m 2 denotes grams of carbon per square meter.)
1989 REVIEW
159
Station 7
Station
Biomass (/Lgc.1-1) n
50 -c
0
0 1 2 3 01 I I I
O\
a)
100
Biomass (ag&1-1)
1 2 3
T /
21
.\
I
/o I 0 0 •'—'
50
-c
0 0
0 0) 0 100 0
0
O—OAutotrophs •—• Heterotrophs Figure 2. Vertical distributions of total autotrophic and heterotrophic biomass at a selected ice-covered station (station 7) and at a station from open water (station 21). (m denotes meter. pigC •1 1 denotes micrograms of carbon per liter.)
AMERIEZ 1988: Winter protozooplankton from the Weddell and Scotia Seas MARCIA M. GowiNc, DAVID L. GARRISON, KURT R. BUCK, and SUSAN L. COALE Institute of Marine Sciences University of California Santa Cruz, California 95064
As part of the Antarctic Marine Ecosystem Research at the Ice-Edge Zone (AMERIEZ) project, we are studying the distributions, abundances, and trophic ecology of heterotrophic protozooplankton. Protozooplankton range in size from microflagellates a few micrometers in length up to colonial radiolarians that can reach meters in size. In this report, we focus on protozooplankton ranging from 50 to 300 micrometers in their longest dimension. These include radiolarians, forami 160
niferans, heliozoans, and some ciliates. Samples were collected along several transects perpendicular to the ice edge during the AMERIEZ 88 cruise (see cruise track in Ainley and Sullivan, Antarctic Journal, this issue) in the austral winter from 9 June to 13 August 1988. We took both quantitative plankton tows and large-volume (60-liter) water samples; this report discusses preliminary results based on analysis of water samples from 8 of 17 stations. At each station, 30 liters of water were collected from each of 10 depths: 5 + 10 meters, 30 + 40 meters, 65 + 85 meters, 115 + 135 meters, and 190 + 210 meters. Samples from each pair of combined depths were concentrated to 200 milliliters by reverse-flow filtration (Garrison and Buck 1989) immediately after collection and preserved with Karnovsky's fixative (Garrison and Buck 1989). Upon return to our laboratory, samples were stained with the nuclear fluorochrome DAPI (Coleman 1980), concentrated in settling chambers, and examined with an inverted fluorescence microscope. The nuclear stain allowed us to distinguish between organisms that were alive at the time of capture and empty skeletons, and also indicated organisms that were undergoing reproduction. The nuclear stain was also useful for distinguishing organisms in samples with much detritus. ANTARCTIC JOURNAL
