Phytoplankton pigment profiles at the Weddell-Scotia
Deacon, G.E.R. 1982. Physical and biological zonation in the southern ocean. Deep-Sea Research, 29(1A), 1-15. Dell, R.K. 1964. Antarctic and subantarctic mollusca: Amphineura, Scaphopoda and Bivalvia. Discovery Reports, 32, 93-250. Helmuth, B., R.R. Veit, and R. Holberton. In press. Long-distance dispersal of a subantarctic brooding bivalve (Gaimardia trapesina) by
Scheltema, R.S. 1977. Dispersal of marine invertebrate organisms: Paleobiogeographic and biostratigraphic implications. In E.G. Kauffman and I.E. Hazel (Eds.), Concepts and methods of biostratigraphy. Stroudsberg, Pennsylvania: Dowden, Hutchinson, and Ross. Thiriot-Quievreux, C., J. Soyer, M. Bouvy, and J.A. Allen. 1988. Chromosomes of some subantarctic brooding bivalve species. Veliger, 30(3), 248-256. Thorson, G. 1950. Reproductive and larval ecology of marine bottom invertebrates. Biological Reviews, 25, 1-45. U.S. Defense Mapping Agency. 1988. Sailing directions (planning guide) for the South Atlantic Ocean, 2nd ed. (Pub. 121). Washington, DC: Defense Mapping Agency Hydrographic/Topographic Center. Worcester, S.E. In press. Adult swimming vs. larval swimming: Dispersal and recruitment of a botryllid ascidian on eelgrass. Marine
kelp rafting. Marine Biology.
Highsmith, R.C. 1985. Floating and algal rafting as potential dispersal mechanisms in brooding invertebrates. Marine Ecology Progress Series, 25(2), 169-179. Jackson, J.B.C. 1986. Modes of dispersal of clonal benthic invertebrates: Consequences for species' distributions and genetic structure of local populations. Bulletin of Marine Science, 39(2), 588-606. Ralph, R., and J.G.H. Maxwell. 1977. The oxygen consumption of the antarctic lamellibranch Gaimardia trapesina trapesina in relation to cold adaptation in polar invertebrates. British Antarctic Survey Bulletin, 45, 41-46.
Biology.
Phytoplankton pigment profiles at the Weddell-Scotia Confluence during the 1993 austral spring ANNE C. SIGLEO, U. S. Environmental Protection Agency, Newport, Oregon 97365-5260 PATRICK J. NEALE, Smithsonian Environmental Research Center, Edgewater, Maryland 20715
ajor and accessory phytoplankton pigments were examM ined in regions of high and low phytoplankton biomass at the confluence of the Scotia and Weddell Seas as part of an investigation of the effects of stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B) radiation (280 to 320 nanometers) on phytoplankton photosynthetic processes (Neale and Spector, Antarctic Journal, in this issue). Pigment analyses were designed to supply supporting data for potential biochemical changes, repair, and long-term adaptations due to UV-B radiation exposure. Pigment data also can provide insight on complex watermass -biomass interactions (Bidigare et al. 1986; Klein and Sournia 1987; Buma et al. 1990). Phytoplankton for pigment analyses were collected on glass-fiber filters from 1-2 liters of seawater collected at 10- to 20-meter depth intervals with Niskin samplers. The filters were submerged immediately in 1.5-milliliter 95-percent acetone (100-percent acetone with a wet filter), extracted for 24 hours at -20°C in the dark, and analyzed shipboard by reverse-phase, high-performance liquid chromatography (HPLC). Acetone-extractable pigments were separated using a three-step solvent gradient based on the solvent compositions and ion pairing solution of Mantoura and Llewellyn (1983). Chlorophyll pigments were detected with a Waters Model 420 fluorescence detector (excitation 400-460 nanometers, emission greater than 600 nanometers) paired sequentially with a Hewlett Packard 1050 variable wavelength UV-visible absorbance detector programmed to 440 nanometers for carotenoids. The pigment concentrations were determined from calibrations with authentic standards of the available pigments (Sigma Chemical Company). Lutein was used to obtain a response factor for the xanthophyll pigments and chlorophyll-a was used for the fluorescence response fac-
tor. The relative retention time for each pigment was determined from pure cultures of phytoplankton with well-established pigment contents (Wright et al. 1991), and the chlorophyllides and phaeopigments were derived chemically from chlorophyll-a (Mantoura and Llewellyn 1983). During October and November 1993, the Weddell-Scotia Confluence near 60°S 50°W was delineated by a sharp biomass front about 100 kilometers north of the ice edge (Neale and Spector, Antarctic Journal, in this issue). Stations A and B, located within the biomass front, had a well-developed upper mixed layer with a sharp pycnocline at 60 to 80 meters depth. Chlorophyll-a concentrations in the upper 100 meters ranged from 0.1 micrograms per liter south of the front to over 6.5 micrograms per liter north of the front. Although higher than HPLC values reported previously for the southern oceans (Bidigare et al. 1986; Buma et al. 1990), similar ranges in chlorophyll-a concentrations have been reported during algal blooms in temperate waters (Klein and Sournia 1987). Large concentrations of the accessory pigments fucoxanthin, (average, 3.9 micrograms per liter) and chlorophyll-c (average, 1.1 microgram per liter) were present, along with significant amounts of the photoprotective carotenoids, diadinoxanthin (DD), and diatoxanthin (DT). Fucoxanthin was the most abundant carotenoid and generally covaried with chlorophyll-a, chlorophyllide-a, or the sum of the two (figure 1). These results suggest that fucoxanthin is more stable than chlorophyll-a, and as chlorophyll-a degrades to chlorophyllide-a, fucoxanthin remains and accumulates along with chlorophyllide-a. The large amount of fucoxanthin is characteristic of diatoms, in accord with the identity of Thalassiosira gravida as the predominant species in the water column. The T. gravida occurred in large colonies up to sever-
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STATION 93C291
STATION 93A291 0
0
- 50-
50
0
0
50
50
100
100
150
150
- 100
- 100
*Chlorophyll a ° 150 1 C-Ihdea - 150 Ch1orophyII C Phycobi1in I 200 200 0 1 2 3 0
Fucoxanthin Diadino
2 3
STATION 9313291 0 , .
CONCENTRATION (jig U') CONCENTRATION (Jig L4)
0
Figure 2. Vertical distribution of pigments at station C, south of the Weddell-Scotia Confluence biomass front. Pigment concentrations
-D 50
100
150 200
_o-
5
100
*Chlorophyll a a rC-Ilide - --150 hlorophyll C hycobi1in 0
I I 200 200 0 0.25 0.5 0.75 1 0 0.05 0.1 0.15 0.2
200 2 3 0
2 3
CONCENTRATION (jig L4 ) CONCENTRATION (jig U') Figure 1. Vertical distributions of chlorophylls (left panels) and carotenoids (right panels) measured at stations A and B within the biomass front. Pigment concentrations are given in micrograms per liter (jig L-1 ); depth is in meters. Dashed lines denote chlorophyllide-a.
al millimeters in length. The high concentration of accessory pigments in the water-column assemblages suggests adaptation to low-light conditions (Perry, Talbot, and Alberte 1981), consistent with a low ratio of euphotic-zone depth (approximately 30 meters) to mixed-layer depth (approximately 80 meters). Chlorophyll-b concentrations were low (20 nanograms per liter) or below the detection limit. Phycoerythrin, indicative of cyanobacteria, was minor (approximately 200 nanograms per liter) but persistent at all stations. 19'hexanoylfucoxanthin, characteristic of Phaeocystis sp., was present at several stations in the range 20-150 nanograms per liter. Peridinin and violaxanthin were detected (approximately 20 nanograms per liter) only in several samples. Chlorophyllide-a varied in concentration from 0.06 to over 3 micrograms per liter, and constituted up to 35 percent of the total sample pigment and over 95 percent of the chlorophyll degradation products at stations A and B. The concentrations of chlorophyllide-a, a hydrolysis product of chlorophyll-a found in senescent cells, frequently increased when those of chlorophyll-a decreased (figure 1) and was below the detection limit south of the biomass front (figure 2). High concentrations of chlorophyllide-a at several stations indicate that phytoplankton senescence and/or zooplankton grazing had localized impact on pigment compositions (Bidigare et al.
1986; Jeffrey and Hallegraeff 1987). Since chlorophyllide-a concentrations can exceed those of chlorophyll-a in mature cells, these results from the southern ocean emphasize the need for complete pigment analyses to avoid errors in estimations of photosynthetically active biomass. We thank other members of the UV-B/Ozone 93 team, the officers and crew of the R/V Nathaniel B. Palmer, and Antarctic Support Associates for logistic support. This research was supported by National Science Foundation grant OPP 92-20373 to P.J. Neale and J.J. Cullen. (This is ERLN publication N-280.)
References Bidigare, R.R., R.J. Frank, C. Zastrow, and J.M. Brooks. 1986. The distribution of algal chlorophylls and their degradation products in the southern ocean. Deep-Sea Research, 33(7), 923-937. Buma, A.G.J., G.W. Treguer, G.W. Kraay, and J. Morvan. 1990. Algal pigment patterns in different watermasses of the Atlantic sector of the southern ocean during fall 1987. PolarBiology, 11(1), 55-62. Jeffrey, S.W., and G.M. Hallegraeff. 1987. Chiorophyllase distribution in ten classes of phytoplankton: A problem for chlorophyll analysis. Marine Ecology Progress Series, 35(3), 293-304. Klein, B., and A. Sournia. 1987. A daily study of the diatom spring bloom at Roscoff (France) in 1985. II. Phytoplankton pigment composition studied by HPLC analysis. Marine Ecology Progress Series, 37(2-3), 265-275. Mantoura, R.F.C., and C.A. Llewellyn- 1983. The rapid determination of algal chlorophyll and carotenoid pigments and their breakdown products in natural waters by reverse-phase high performance liquid chromatography. Analytical ChimicaActa, 151(2), 297-314. Neale, P.J., and A.M. Spector. 1994. UV absorbance by diatom populations from the Weddell-Scotia Confluence. Antarctic Journal of the U.S., 29(5). Perry, M., M. Talbot, and R. Alberte. 1981. Photoadaptation in marine phytoplankton: response of the photosynthetic unit. Marine Biology, 62(2/3),91-101. Wright, S. W., S.W. Jeffery, R.F.C. Mantuora, C.A. Liewellyn, T. Bjornland, D. Repeta, and N. Welschmeyer. 1991. Improved HPLC method for the analysis of chlorophylls and carotenoids from marine phytoplankton. Marine Ecology Progress Series, 77(2/3), 183-196.
ANTARCTIC JOURNAL - REVIEW 1994 148
Scheltema, R.S. 1977. Dispersal of marine invertebrate organisms: Paleobiogeographic and biostratigraphic implications. In E.G. Kauffman and I.E. Hazel (Eds.), Concepts and methods of biostratigraphy. Stroudsberg, Pennsylvania: Dowden, Hutchinson, and Ross. Thiriot-Quievreux, C., J. Soyer, M. Bouvy, and J.A. Allen. 1988. Chromosomes of some subantarctic brooding bivalve species. Veliger, 30(3), 248-256. Thorson, G. 1950. Reproductive and larval ecology of marine bottom invertebrates. Biological Reviews, 25, 1-45. U.S. Defense Mapping Agency. 1988. Sailing directions (planning guide) for the South Atlantic Ocean, 2nd ed. (Pub. 121). Washington, DC: Defense Mapping Agency Hydrographic/Topographic Center. Worcester, S.E. In press. Adult swimming vs. larval swimming: Dispersal and recruitment of a botryllid ascidian on eelgrass. Marine
kelp rafting. Marine Biology.
Highsmith, R.C. 1985. Floating and algal rafting as potential dispersal mechanisms in brooding invertebrates. Marine Ecology Progress Series, 25(2), 169-179. Jackson, J.B.C. 1986. Modes of dispersal of clonal benthic invertebrates: Consequences for species' distributions and genetic structure of local populations. Bulletin of Marine Science, 39(2), 588-606. Ralph, R., and J.G.H. Maxwell. 1977. The oxygen consumption of the antarctic lamellibranch Gaimardia trapesina trapesina in relation to cold adaptation in polar invertebrates. British Antarctic Survey Bulletin, 45, 41-46.
Biology.
Phytoplankton pigment profiles at the Weddell-Scotia Confluence during the 1993 austral spring ANNE C. SIGLEO, U. S. Environmental Protection Agency, Newport, Oregon 97365-5260 PATRICK J. NEALE, Smithsonian Environmental Research Center, Edgewater, Maryland 20715
ajor and accessory phytoplankton pigments were examM ined in regions of high and low phytoplankton biomass at the confluence of the Scotia and Weddell Seas as part of an investigation of the effects of stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B) radiation (280 to 320 nanometers) on phytoplankton photosynthetic processes (Neale and Spector, Antarctic Journal, in this issue). Pigment analyses were designed to supply supporting data for potential biochemical changes, repair, and long-term adaptations due to UV-B radiation exposure. Pigment data also can provide insight on complex watermass -biomass interactions (Bidigare et al. 1986; Klein and Sournia 1987; Buma et al. 1990). Phytoplankton for pigment analyses were collected on glass-fiber filters from 1-2 liters of seawater collected at 10- to 20-meter depth intervals with Niskin samplers. The filters were submerged immediately in 1.5-milliliter 95-percent acetone (100-percent acetone with a wet filter), extracted for 24 hours at -20°C in the dark, and analyzed shipboard by reverse-phase, high-performance liquid chromatography (HPLC). Acetone-extractable pigments were separated using a three-step solvent gradient based on the solvent compositions and ion pairing solution of Mantoura and Llewellyn (1983). Chlorophyll pigments were detected with a Waters Model 420 fluorescence detector (excitation 400-460 nanometers, emission greater than 600 nanometers) paired sequentially with a Hewlett Packard 1050 variable wavelength UV-visible absorbance detector programmed to 440 nanometers for carotenoids. The pigment concentrations were determined from calibrations with authentic standards of the available pigments (Sigma Chemical Company). Lutein was used to obtain a response factor for the xanthophyll pigments and chlorophyll-a was used for the fluorescence response fac-
tor. The relative retention time for each pigment was determined from pure cultures of phytoplankton with well-established pigment contents (Wright et al. 1991), and the chlorophyllides and phaeopigments were derived chemically from chlorophyll-a (Mantoura and Llewellyn 1983). During October and November 1993, the Weddell-Scotia Confluence near 60°S 50°W was delineated by a sharp biomass front about 100 kilometers north of the ice edge (Neale and Spector, Antarctic Journal, in this issue). Stations A and B, located within the biomass front, had a well-developed upper mixed layer with a sharp pycnocline at 60 to 80 meters depth. Chlorophyll-a concentrations in the upper 100 meters ranged from 0.1 micrograms per liter south of the front to over 6.5 micrograms per liter north of the front. Although higher than HPLC values reported previously for the southern oceans (Bidigare et al. 1986; Buma et al. 1990), similar ranges in chlorophyll-a concentrations have been reported during algal blooms in temperate waters (Klein and Sournia 1987). Large concentrations of the accessory pigments fucoxanthin, (average, 3.9 micrograms per liter) and chlorophyll-c (average, 1.1 microgram per liter) were present, along with significant amounts of the photoprotective carotenoids, diadinoxanthin (DD), and diatoxanthin (DT). Fucoxanthin was the most abundant carotenoid and generally covaried with chlorophyll-a, chlorophyllide-a, or the sum of the two (figure 1). These results suggest that fucoxanthin is more stable than chlorophyll-a, and as chlorophyll-a degrades to chlorophyllide-a, fucoxanthin remains and accumulates along with chlorophyllide-a. The large amount of fucoxanthin is characteristic of diatoms, in accord with the identity of Thalassiosira gravida as the predominant species in the water column. The T. gravida occurred in large colonies up to sever-
ANTARCTIC JOURNAL - REVIEW 1994
147
STATION 93C291
STATION 93A291 0
0
- 50-
50
0
0
50
50
100
100
150
150
- 100
- 100
*Chlorophyll a ° 150 1 C-Ihdea - 150 Ch1orophyII C Phycobi1in I 200 200 0 1 2 3 0
Fucoxanthin Diadino
2 3
STATION 9313291 0 , .
CONCENTRATION (jig U') CONCENTRATION (Jig L4)
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Figure 2. Vertical distribution of pigments at station C, south of the Weddell-Scotia Confluence biomass front. Pigment concentrations
-D 50
100
150 200
_o-
5
100
*Chlorophyll a a rC-Ilide - --150 hlorophyll C hycobi1in 0
I I 200 200 0 0.25 0.5 0.75 1 0 0.05 0.1 0.15 0.2
200 2 3 0
2 3
CONCENTRATION (jig L4 ) CONCENTRATION (jig U') Figure 1. Vertical distributions of chlorophylls (left panels) and carotenoids (right panels) measured at stations A and B within the biomass front. Pigment concentrations are given in micrograms per liter (jig L-1 ); depth is in meters. Dashed lines denote chlorophyllide-a.
al millimeters in length. The high concentration of accessory pigments in the water-column assemblages suggests adaptation to low-light conditions (Perry, Talbot, and Alberte 1981), consistent with a low ratio of euphotic-zone depth (approximately 30 meters) to mixed-layer depth (approximately 80 meters). Chlorophyll-b concentrations were low (20 nanograms per liter) or below the detection limit. Phycoerythrin, indicative of cyanobacteria, was minor (approximately 200 nanograms per liter) but persistent at all stations. 19'hexanoylfucoxanthin, characteristic of Phaeocystis sp., was present at several stations in the range 20-150 nanograms per liter. Peridinin and violaxanthin were detected (approximately 20 nanograms per liter) only in several samples. Chlorophyllide-a varied in concentration from 0.06 to over 3 micrograms per liter, and constituted up to 35 percent of the total sample pigment and over 95 percent of the chlorophyll degradation products at stations A and B. The concentrations of chlorophyllide-a, a hydrolysis product of chlorophyll-a found in senescent cells, frequently increased when those of chlorophyll-a decreased (figure 1) and was below the detection limit south of the biomass front (figure 2). High concentrations of chlorophyllide-a at several stations indicate that phytoplankton senescence and/or zooplankton grazing had localized impact on pigment compositions (Bidigare et al.
1986; Jeffrey and Hallegraeff 1987). Since chlorophyllide-a concentrations can exceed those of chlorophyll-a in mature cells, these results from the southern ocean emphasize the need for complete pigment analyses to avoid errors in estimations of photosynthetically active biomass. We thank other members of the UV-B/Ozone 93 team, the officers and crew of the R/V Nathaniel B. Palmer, and Antarctic Support Associates for logistic support. This research was supported by National Science Foundation grant OPP 92-20373 to P.J. Neale and J.J. Cullen. (This is ERLN publication N-280.)
References Bidigare, R.R., R.J. Frank, C. Zastrow, and J.M. Brooks. 1986. The distribution of algal chlorophylls and their degradation products in the southern ocean. Deep-Sea Research, 33(7), 923-937. Buma, A.G.J., G.W. Treguer, G.W. Kraay, and J. Morvan. 1990. Algal pigment patterns in different watermasses of the Atlantic sector of the southern ocean during fall 1987. PolarBiology, 11(1), 55-62. Jeffrey, S.W., and G.M. Hallegraeff. 1987. Chiorophyllase distribution in ten classes of phytoplankton: A problem for chlorophyll analysis. Marine Ecology Progress Series, 35(3), 293-304. Klein, B., and A. Sournia. 1987. A daily study of the diatom spring bloom at Roscoff (France) in 1985. II. Phytoplankton pigment composition studied by HPLC analysis. Marine Ecology Progress Series, 37(2-3), 265-275. Mantoura, R.F.C., and C.A. Llewellyn- 1983. The rapid determination of algal chlorophyll and carotenoid pigments and their breakdown products in natural waters by reverse-phase high performance liquid chromatography. Analytical ChimicaActa, 151(2), 297-314. Neale, P.J., and A.M. Spector. 1994. UV absorbance by diatom populations from the Weddell-Scotia Confluence. Antarctic Journal of the U.S., 29(5). Perry, M., M. Talbot, and R. Alberte. 1981. Photoadaptation in marine phytoplankton: response of the photosynthetic unit. Marine Biology, 62(2/3),91-101. Wright, S. W., S.W. Jeffery, R.F.C. Mantuora, C.A. Liewellyn, T. Bjornland, D. Repeta, and N. Welschmeyer. 1991. Improved HPLC method for the analysis of chlorophylls and carotenoids from marine phytoplankton. Marine Ecology Progress Series, 77(2/3), 183-196.
ANTARCTIC JOURNAL - REVIEW 1994 148
