AMLR program: Distribution of phytoplankton in the upper water ...
t'
Armada, Chile) for their generous help onboard ship. Shipboard personnel included E. Walter Helbling (12 January to 9 February), Virginia Villafañe (12 January to 9 February), Humberto DIaz (12 January to 15 March), and Osmund HolmHansen (14 February to 15 March).
References Helbling, E.W., V.E. Villafane, and 0. Holm-Hansen. In press. Variability of phytoplankton distribution and primary production around Elephant Island, Antarctica, during 1990-1993. Polar Biology. Holm-Hansen, 0., C.J. Lorenzen, R.W. Holmes, and J.D.H. Strickland. 1965. Fluorometric determination of chlorophyll. Journal de Conseil pour L'Exploration de laMer, 30(1), 3-15. Holm-Hansen, 0., and B. Riemann. 1978. Chlorophyll-a determination: Improvements in methodology. OIKOS, 30(3),438-447.
of phytoplankton cell numbers, cell volume, cell surface and plasma volumes per liter, from microscopical counts (Special Report 38). Seattle:
Kovala, P.E., and J.D. Larrance. 1966. Computation
Department of Oceanography, University of Washington. Rosenberg J.E., R.P. Hewitt, and R.S. Holt. 1994. The U.S. Antarctic Marine Living Resources (AMLR) program: 1993-1994 field season activities. Antarctic Journal of the U.S., 29(5). Strathmann, R.R. 1967. Estimating the organic carbon content of phytoplankton from cell volume or plasma volume. Limnology and Oceanography, 12(3), 411-418. Utermöhl, H. 1958. Toward the improvement of the quantitative phy-
toplankton method. Mitteilungen-Internationale Verein igung für Theoretische undAngewandte Limnologie, No. 9,1-38. (In German) Villafañe, V.E. 1993. Patterns of distribution of phytoplankton species and biomass in the vicinity of Elephant Island, Antarctica, during summer 1990-1992. (Masters of Science Thesis, University of California at San Diego).
AMLR program: Distribution of phytoplankton in the upper water column in relation to different water masses E. WALTER HELBLING and OSMUND HOLM-HANSEN, Polar Research Program, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0202
part of the Antarctic Marine Living Resources (AMLR) ;rogram, our phytoplankton project conducted intensive studies in the area around Elephant Island, Antarctica, onboard the National Oceanic and Atmospheric Administration (NOAA) ship Surveyor, January through March 1994. The cruise track and station positions are given in Rosenberg, Hewitt, and Holt (Antarctic Journal, in this issue). In this paper, we present information on the distribution of phytoplankton with depth as related to the major water masses present in the AMLR study area. Detailed biological-physical-optical data were obtained throughout the upper water column [0 to 750 meters (m)] at every station using a General Oceanics rosette equipped with 1110-liter Niskin bottles and the following: • a conductivity-temperature-depth sensor (CTD, Sea Bird Inc., SBE-9), • a pulsed fluorometer (Sea Tech), • a 25-centimeter pathlength transmissometer (Sea Tech), and • a photosynthetically available radiation (PAR) sensor. A profiling PUV-500 unit (Biospherical Instruments, Inc.) was also deployed at every daylight station (when weather permitted) down to 100 m to obtain information on the attenuation of solar radiation at 305, 320, 340, and 380 nanometers in the ultraviolet region of the spectrum, in addition to PAR at 400-700 nanometers. The instantaneous rate of photosynthesis was estimated using the 683 nanometers upwelling radiation sensor located on the bottom of the PUV-500 unit (Chamberlin et al. 1990). Various water masses are normally encountered in the Elephant Island area (Amos and Lavender 1992), but the ones
that are most evident and widespread in the upper 200 in the water column are those characterized as Drake Passage waters, Bransfield Strait waters, and Bransfield-Scotia Confluence waters (Silva et al. in press). Data from representative stations in Drake Passage and Bransfield Strait waters are discussed below. Station D04 (figure 1) was located in the Bransfield Strait and presented a relatively shallow upper mixed layer (UML) of about 30 m, as estimated from the density profile. Chlorophyll-a (chl-a) concentrations were high within the UML at up to 1.3 milligrams per cubic meter (mg rn- 3 ) but decreased rapidly below it (figure 1A). Some photoinhibition of chl-a fluorescence was evident down to 25 m, but no inhibition of the instantaneous rate of primary production was noted (figure 1B). The depth of the euphotic zone (1 percent of surface irradiance) for this station was about 68 m. Station D51 (figure 2), located in Bransfield Strait waters to the northeast of King George Island, had a deeper UML of 50 in was much richer in regard to phytoplankton biomass. Chl-a concentrations were high in the upper 50 in the water column (up to 4 mg rn- 3 ) and were still fairly high (1.8 mg rn- 3 ) at 75 in 2A). Instantaneous production rates were also high in the upper part of the UML with rates exceeding 500 nanornoles of carbon fixed per cubic meter per second (nmole C rn-3 s_1) (figure 2B); these high rates equate to an assimilation value of approximately 5.4 mg C mg chl-a' hr'. The 1 percent light level for this station was about 35 m. In contrast to stations in Bransfield Strait waters, stations located in Drake Passage waters showed a subsurface chl-a maximum below the pycnocline. Data from Station D43 (figure 3) show that chl-a was higher between 50 and 100 in
ANTARCTIC JOURNAL - REVIEW 1994 193
: igure 1. Upper water column characteristics (0 to 200 m) for Station D04. A. Mater density (sigma-t), chl-a concentrations (solid circles; mg rn- 3), and in 'ivo chl-a fluorescence (relative units). B. Instantaneous rates of primary proluction (nanornole carbon per cubic meter per second) and attenuation of AR (in microeinsteins per square centimeter per second).
Density (sigma-t)
26.9 27 27.1 27.2 27.3 27.4 27.5 27.6 27.7 25 In vivo f ........... l uor.
Chia
.75 100r............................................. 125
Sigmat A
150 200 1
0.5 1 1.5 2 2.5 3 3.5 4
ChI-a (mg/m3)
Station D43. A. Water density (sigma-t), chl-a concentrations (solid circles; mg rn-3), and in vivo chl-a fluorescence (relative units). B. Instantaneous rates of primary production (nanomole carbon per cubic meter per second) and attenuation of PAR (in microeinstein per square centimeter per second).
Production (nM CIm3Is)
0 100 200 300 400 500 600 700 800 900 1,000
:JIIJPATT.
75 7
,..
. .
.0 100 . 0.
125
. il. .
150 . 41 . : I 175
B
IE-006 IE-005 0.0001 0.001 0.01 0.1 PAR (uEIcm2Is)
Figure 2. Upper water column characteristics (0 to 200 m) for Station D51. A. Water density (sigma-t), chl-a concentrations (solid circles; mg rn- 3), and in vivo chl-a fluorescence (relative units). B. Instantaneous rates of primary production (nanomole carbon per cubic meter per second) and attenuation of PAR (in microeinsteins per square centimeter per second).
ANTARCTIC JOURNAL 194
-
REVIEW 1994
in the UML (0 to 50 m; figure 3A). The high phytoplankton biomass below the UML was also reflected in the rate at which instantaneous production decreased with depth. In contrast to data in figures 1 and 2, the rates of primary production between 25 to 75 m remained relatively high as compared to values in the upper 25 m of the water column (figure 3B). Evidence for high phytoplankton biomass between 50 and 100 m is also seen in the increased rates of attenuation of solar radiation with depth. The 1 percent light level for this station was about 95 m. The above results are consistent with other data acquired throughout the AMLR sampling grid on the distribution of phytoplankton as determined by microscopic methods (Villafane et al., Antarctic Journal, in this issue) and on rates of primary production as estimated by radiocarbon techniques (Holm-Hansen, Villafañe, and Heibling 1994). It has been suggested (Holm-Hansen et al. 1994) that this dramatic difference in distribution of phytoplankton in the upper water column between Drake Passage and Bransfield Strait waters is due to iron limitation in the UML of stations in Drake Passage waters. This work was supported by National Oceanic and Atmospheric Administration (NOAA) Cooperative Agreement number NA47FR0030. We thank the officers and crew of the NOAA ship Surveyor for excellent support during the field operations. We also thank Virginia Villafane, Humberto DIaz, Christian Bonert, Pedro BarOn, and Marcel Ramos for help
onboard ship. Shipboard personnel included E. Walter Helbling (13 January to 9 February) and Osmund Holm-Hansen (14 February to 15 March).
References Amos, A.F., and M.K. Lavender. 1992. AMLR program: Dynamics of the summer hydrographic regime at Elephant Island. Antarctic Journal of the U.S., 27(5), 228-230. Chamberlin, W.S., C.R. Booth, D.A. Kiefer, J.H. Morrow, and R.C. Murphy. 1990. Evidence for a simple relationship between natural fluorescence, photosynthesis and chlorophyll in the sea. Deep-Sea Research, 37(6), 951-973. Holm-Hansen, 0., A.F. Amos, N. Silva S., V.E. Villafañe, and E.W. Helbling. 1994. In situ evidence for a nutrient limitation of phytoplankton growth in pelagic antarctic waters. Antarctic Science, 6(3), 315-324. Holm-Hansen, 0., V.E. Villafane, and E.W. Helbling. 1994. AMLR program: Photobiological characteristics of phytoplankton around Elephant Island, Antarctica. Antarctic Journal of the U.S., 29(5). Rosenberg, J.E., R.P. Hewitt, and R.S. Holt. 1994. The U.S. Antarctic Marine Living Resources (AMLR) program: 1993-1994 field season activities. Antarctic Journal of the U.S., 29(5). Silva S., N., E.W. Helbling, V.E. Villafane, A.F. Amos, and 0. HolmHansen. In press. Variability in nutrient concentrations around Elephant Island, Antarctica, during 1991-1993. Polar Research. Villafañe, V.E., E.W. Helbling, 0. Holm-Hansen, and H. DIaz. 1994. AMLR Program: Phytoplankton distribution and species composition around Elephant Island, Antarctica, January to March 1994. Antarctic Journal of the U.S., 29(5).
AMLR program: Depletion of inorganic nutrients in the area around Elephant Island, Antarctica NELSON SILVA S. and MARCEL RAMOS, Escuela de Ciencias del Mar, Universidad Católica de Valparaiso, Valparaiso, Chile
E. WALTER HELBLING and OSMUND HOLM-HANSEN, Polar Research Program, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0202
shaken, and discarded two times. The 60-milliliter bottles were then filled approximately three-fourths full with water from the 10-liter Niskin bottles and frozen (-20°C) immediately. The samples were kept frozen until analyses (1-2 months after collection), which were performed at the Universidad CatOlica de Valparaiso, Chile, using an autoanalyzer and employing the technique described by Atlas et al. (1971). Nitrate concentrations at 5 meters depth were high during Survey A: values ranged from about 22.3 to more than 29 micromolar (tM) (figure 1A). During Survey D, nitrogen values decreased in the area to the south and southeast of King George Island and also in the area between King George Island and Elephant Island (figure 1B), but nitrate concentrations increased in coastal waters around King George Island, as well as in deep waters to the north of the island. Nitrate concentrations during Survey D ranged from 20 to 34 tiM. Phosphate concentrations at 5 meters depth varied from 1.65 to more than 2.1 tM during Survey A (figure 2A). Rela-
norganic nutrient concentrations are generally high in I antarctic waters, but significant depletions of nitrogen, phosphorus, and silicic acid have been documented in coastal areas where large phytoplankton blooms occurred (Nelson and Smith 1986; Holm-Hansen and Mitchell 1991). In this paper, we report the concentrations of these inorganic nutrients from January to March 1994 in a large sampling grid around Elephant Island. The grid included both coastal and pelagic stations. The cruise track and station positions are given in Rosenberg, Hewitt, and Holt (Antarctic Journal, in this issue). As one component of the phytoplankton studies of the Antarctic Marine Living Resources (AMLR) program, samples for determination of nutrient concentrations were obtained at each station, during both Legs I and II, using 10-liter Niskin bottles mounted on the rosette profiling system. Water from the Niskin bottles was poured directly into 60-milliliter, clean (soaked in 1.0 normal hydrochloric acid) polyethylene bottles,
ANTARCTIC JOURNAL - REVIEW 1994
195
Armada, Chile) for their generous help onboard ship. Shipboard personnel included E. Walter Helbling (12 January to 9 February), Virginia Villafañe (12 January to 9 February), Humberto DIaz (12 January to 15 March), and Osmund HolmHansen (14 February to 15 March).
References Helbling, E.W., V.E. Villafane, and 0. Holm-Hansen. In press. Variability of phytoplankton distribution and primary production around Elephant Island, Antarctica, during 1990-1993. Polar Biology. Holm-Hansen, 0., C.J. Lorenzen, R.W. Holmes, and J.D.H. Strickland. 1965. Fluorometric determination of chlorophyll. Journal de Conseil pour L'Exploration de laMer, 30(1), 3-15. Holm-Hansen, 0., and B. Riemann. 1978. Chlorophyll-a determination: Improvements in methodology. OIKOS, 30(3),438-447.
of phytoplankton cell numbers, cell volume, cell surface and plasma volumes per liter, from microscopical counts (Special Report 38). Seattle:
Kovala, P.E., and J.D. Larrance. 1966. Computation
Department of Oceanography, University of Washington. Rosenberg J.E., R.P. Hewitt, and R.S. Holt. 1994. The U.S. Antarctic Marine Living Resources (AMLR) program: 1993-1994 field season activities. Antarctic Journal of the U.S., 29(5). Strathmann, R.R. 1967. Estimating the organic carbon content of phytoplankton from cell volume or plasma volume. Limnology and Oceanography, 12(3), 411-418. Utermöhl, H. 1958. Toward the improvement of the quantitative phy-
toplankton method. Mitteilungen-Internationale Verein igung für Theoretische undAngewandte Limnologie, No. 9,1-38. (In German) Villafañe, V.E. 1993. Patterns of distribution of phytoplankton species and biomass in the vicinity of Elephant Island, Antarctica, during summer 1990-1992. (Masters of Science Thesis, University of California at San Diego).
AMLR program: Distribution of phytoplankton in the upper water column in relation to different water masses E. WALTER HELBLING and OSMUND HOLM-HANSEN, Polar Research Program, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0202
part of the Antarctic Marine Living Resources (AMLR) ;rogram, our phytoplankton project conducted intensive studies in the area around Elephant Island, Antarctica, onboard the National Oceanic and Atmospheric Administration (NOAA) ship Surveyor, January through March 1994. The cruise track and station positions are given in Rosenberg, Hewitt, and Holt (Antarctic Journal, in this issue). In this paper, we present information on the distribution of phytoplankton with depth as related to the major water masses present in the AMLR study area. Detailed biological-physical-optical data were obtained throughout the upper water column [0 to 750 meters (m)] at every station using a General Oceanics rosette equipped with 1110-liter Niskin bottles and the following: • a conductivity-temperature-depth sensor (CTD, Sea Bird Inc., SBE-9), • a pulsed fluorometer (Sea Tech), • a 25-centimeter pathlength transmissometer (Sea Tech), and • a photosynthetically available radiation (PAR) sensor. A profiling PUV-500 unit (Biospherical Instruments, Inc.) was also deployed at every daylight station (when weather permitted) down to 100 m to obtain information on the attenuation of solar radiation at 305, 320, 340, and 380 nanometers in the ultraviolet region of the spectrum, in addition to PAR at 400-700 nanometers. The instantaneous rate of photosynthesis was estimated using the 683 nanometers upwelling radiation sensor located on the bottom of the PUV-500 unit (Chamberlin et al. 1990). Various water masses are normally encountered in the Elephant Island area (Amos and Lavender 1992), but the ones
that are most evident and widespread in the upper 200 in the water column are those characterized as Drake Passage waters, Bransfield Strait waters, and Bransfield-Scotia Confluence waters (Silva et al. in press). Data from representative stations in Drake Passage and Bransfield Strait waters are discussed below. Station D04 (figure 1) was located in the Bransfield Strait and presented a relatively shallow upper mixed layer (UML) of about 30 m, as estimated from the density profile. Chlorophyll-a (chl-a) concentrations were high within the UML at up to 1.3 milligrams per cubic meter (mg rn- 3 ) but decreased rapidly below it (figure 1A). Some photoinhibition of chl-a fluorescence was evident down to 25 m, but no inhibition of the instantaneous rate of primary production was noted (figure 1B). The depth of the euphotic zone (1 percent of surface irradiance) for this station was about 68 m. Station D51 (figure 2), located in Bransfield Strait waters to the northeast of King George Island, had a deeper UML of 50 in was much richer in regard to phytoplankton biomass. Chl-a concentrations were high in the upper 50 in the water column (up to 4 mg rn- 3 ) and were still fairly high (1.8 mg rn- 3 ) at 75 in 2A). Instantaneous production rates were also high in the upper part of the UML with rates exceeding 500 nanornoles of carbon fixed per cubic meter per second (nmole C rn-3 s_1) (figure 2B); these high rates equate to an assimilation value of approximately 5.4 mg C mg chl-a' hr'. The 1 percent light level for this station was about 35 m. In contrast to stations in Bransfield Strait waters, stations located in Drake Passage waters showed a subsurface chl-a maximum below the pycnocline. Data from Station D43 (figure 3) show that chl-a was higher between 50 and 100 in
ANTARCTIC JOURNAL - REVIEW 1994 193
: igure 1. Upper water column characteristics (0 to 200 m) for Station D04. A. Mater density (sigma-t), chl-a concentrations (solid circles; mg rn- 3), and in 'ivo chl-a fluorescence (relative units). B. Instantaneous rates of primary proluction (nanornole carbon per cubic meter per second) and attenuation of AR (in microeinsteins per square centimeter per second).
Density (sigma-t)
26.9 27 27.1 27.2 27.3 27.4 27.5 27.6 27.7 25 In vivo f ........... l uor.
Chia
.75 100r............................................. 125
Sigmat A
150 200 1
0.5 1 1.5 2 2.5 3 3.5 4
ChI-a (mg/m3)
Station D43. A. Water density (sigma-t), chl-a concentrations (solid circles; mg rn-3), and in vivo chl-a fluorescence (relative units). B. Instantaneous rates of primary production (nanomole carbon per cubic meter per second) and attenuation of PAR (in microeinstein per square centimeter per second).
Production (nM CIm3Is)
0 100 200 300 400 500 600 700 800 900 1,000
:JIIJPATT.
75 7
,..
. .
.0 100 . 0.
125
. il. .
150 . 41 . : I 175
B
IE-006 IE-005 0.0001 0.001 0.01 0.1 PAR (uEIcm2Is)
Figure 2. Upper water column characteristics (0 to 200 m) for Station D51. A. Water density (sigma-t), chl-a concentrations (solid circles; mg rn- 3), and in vivo chl-a fluorescence (relative units). B. Instantaneous rates of primary production (nanomole carbon per cubic meter per second) and attenuation of PAR (in microeinsteins per square centimeter per second).
ANTARCTIC JOURNAL 194
-
REVIEW 1994
in the UML (0 to 50 m; figure 3A). The high phytoplankton biomass below the UML was also reflected in the rate at which instantaneous production decreased with depth. In contrast to data in figures 1 and 2, the rates of primary production between 25 to 75 m remained relatively high as compared to values in the upper 25 m of the water column (figure 3B). Evidence for high phytoplankton biomass between 50 and 100 m is also seen in the increased rates of attenuation of solar radiation with depth. The 1 percent light level for this station was about 95 m. The above results are consistent with other data acquired throughout the AMLR sampling grid on the distribution of phytoplankton as determined by microscopic methods (Villafane et al., Antarctic Journal, in this issue) and on rates of primary production as estimated by radiocarbon techniques (Holm-Hansen, Villafañe, and Heibling 1994). It has been suggested (Holm-Hansen et al. 1994) that this dramatic difference in distribution of phytoplankton in the upper water column between Drake Passage and Bransfield Strait waters is due to iron limitation in the UML of stations in Drake Passage waters. This work was supported by National Oceanic and Atmospheric Administration (NOAA) Cooperative Agreement number NA47FR0030. We thank the officers and crew of the NOAA ship Surveyor for excellent support during the field operations. We also thank Virginia Villafane, Humberto DIaz, Christian Bonert, Pedro BarOn, and Marcel Ramos for help
onboard ship. Shipboard personnel included E. Walter Helbling (13 January to 9 February) and Osmund Holm-Hansen (14 February to 15 March).
References Amos, A.F., and M.K. Lavender. 1992. AMLR program: Dynamics of the summer hydrographic regime at Elephant Island. Antarctic Journal of the U.S., 27(5), 228-230. Chamberlin, W.S., C.R. Booth, D.A. Kiefer, J.H. Morrow, and R.C. Murphy. 1990. Evidence for a simple relationship between natural fluorescence, photosynthesis and chlorophyll in the sea. Deep-Sea Research, 37(6), 951-973. Holm-Hansen, 0., A.F. Amos, N. Silva S., V.E. Villafañe, and E.W. Helbling. 1994. In situ evidence for a nutrient limitation of phytoplankton growth in pelagic antarctic waters. Antarctic Science, 6(3), 315-324. Holm-Hansen, 0., V.E. Villafane, and E.W. Helbling. 1994. AMLR program: Photobiological characteristics of phytoplankton around Elephant Island, Antarctica. Antarctic Journal of the U.S., 29(5). Rosenberg, J.E., R.P. Hewitt, and R.S. Holt. 1994. The U.S. Antarctic Marine Living Resources (AMLR) program: 1993-1994 field season activities. Antarctic Journal of the U.S., 29(5). Silva S., N., E.W. Helbling, V.E. Villafane, A.F. Amos, and 0. HolmHansen. In press. Variability in nutrient concentrations around Elephant Island, Antarctica, during 1991-1993. Polar Research. Villafañe, V.E., E.W. Helbling, 0. Holm-Hansen, and H. DIaz. 1994. AMLR Program: Phytoplankton distribution and species composition around Elephant Island, Antarctica, January to March 1994. Antarctic Journal of the U.S., 29(5).
AMLR program: Depletion of inorganic nutrients in the area around Elephant Island, Antarctica NELSON SILVA S. and MARCEL RAMOS, Escuela de Ciencias del Mar, Universidad Católica de Valparaiso, Valparaiso, Chile
E. WALTER HELBLING and OSMUND HOLM-HANSEN, Polar Research Program, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, California 92093-0202
shaken, and discarded two times. The 60-milliliter bottles were then filled approximately three-fourths full with water from the 10-liter Niskin bottles and frozen (-20°C) immediately. The samples were kept frozen until analyses (1-2 months after collection), which were performed at the Universidad CatOlica de Valparaiso, Chile, using an autoanalyzer and employing the technique described by Atlas et al. (1971). Nitrate concentrations at 5 meters depth were high during Survey A: values ranged from about 22.3 to more than 29 micromolar (tM) (figure 1A). During Survey D, nitrogen values decreased in the area to the south and southeast of King George Island and also in the area between King George Island and Elephant Island (figure 1B), but nitrate concentrations increased in coastal waters around King George Island, as well as in deep waters to the north of the island. Nitrate concentrations during Survey D ranged from 20 to 34 tiM. Phosphate concentrations at 5 meters depth varied from 1.65 to more than 2.1 tM during Survey A (figure 2A). Rela-
norganic nutrient concentrations are generally high in I antarctic waters, but significant depletions of nitrogen, phosphorus, and silicic acid have been documented in coastal areas where large phytoplankton blooms occurred (Nelson and Smith 1986; Holm-Hansen and Mitchell 1991). In this paper, we report the concentrations of these inorganic nutrients from January to March 1994 in a large sampling grid around Elephant Island. The grid included both coastal and pelagic stations. The cruise track and station positions are given in Rosenberg, Hewitt, and Holt (Antarctic Journal, in this issue). As one component of the phytoplankton studies of the Antarctic Marine Living Resources (AMLR) program, samples for determination of nutrient concentrations were obtained at each station, during both Legs I and II, using 10-liter Niskin bottles mounted on the rosette profiling system. Water from the Niskin bottles was poured directly into 60-milliliter, clean (soaked in 1.0 normal hydrochloric acid) polyethylene bottles,
ANTARCTIC JOURNAL - REVIEW 1994
195
