Cruise Report Sea Education Association Cruise S-210 Scientific data collected aboard SSV Robert C. Seamans

Transcription

1 Cruise Report Sea Education Association Cruise S-210 Scientific data collected aboard SSV Robert C. Seamans Honolulu, Hawaii Palmyra Atoll - Kiritimati Island, Kiribati - Honolulu, Hawaii 27 March May 2007 Sea Education Association Woods Hole, Massachusetts

2 Citation: Witting, Jan, Final Report for S.E.A. cruise S-210. Sea Education Association, P.O. Box 6, Woods Hole, MA 02543, USA. To obtain unpublished data, contact the Chief Scientist or the SEA Data Archivist: Data Archivist Sea Education Association P.O. Box 6 Woods Hole, MA Phone: Fax: data_archive@sea.edu Web: 2

3 Table of Contents Ship s Company 4 Data description and Cruise Narrative 5 Figure 1: Cruise track 5 Figure 2: Sea surface Temperature and Salinity 8 Figure 3a: Salinity and Temperature sections, southbound leg 9 Figure 3b: Salinity and Temperature sections, northbound leg 10 Figure 4a: Chlorophyll fluorescence and Dissolved Oxygen concentration sections, southbound leg 11 Figure 4a: Chlorophyll fluorescence and Dissolved Oxygen concentration sections, northbound leg 12 Figure 5: ADCP-derived current velocity sections, eastward Projection, north and soutbound legs 13 Table 1: Oceanographic sampling stations 14 Table 2: Hydrocast Data Summary 16 Table 3: Neuston Net Data Summary 26 Table 4: Meter Net Data Summary 27 Table 5: Student Research Projects 28 3

4 Ship s Company SSV Robert C. Seamans, Cruise S-210 Nautical Staff Christopher McGuire Jullie Jackson John O Keefe Colleen Allard Alden Johnson Christopher Weng Christi Lindarich Julia Bertozzi Annie Bailey Julie Gunderson Sarah Gross Mara Snedden Scientific Staff Jan Witting Adam Baske Nate Twitchell Keith Stagg Simone Baumann Xavier Mico Captain Chief Mate Second Mate Third Mate Engineer Steward Assistant Steward Deckhand Deckhand Deckhand Deckhand Deckhand Chief Scientist First Assistant Scientist Second Assistant Scientist Third Assistant Scientist Visiting Scientist, Scripps Visiting Scientist, Scripps Students Katrina Barnes Joshua Bates James Faulkner Julia Gruberg Ana Jamborcic Haley Kuntz Xavier Marvel Caitlin O Hern Sergio Perez Adam Scherr Andrew Sclafani Abigail Taylor Lauren Valentino Miami University Roger Williams University College of Wooster Sarah Lawrence College State University of New York, ESF Hawaii Pacific University University of Massachusetts, Boston Boston College University of California, Santa Barbara University of Vermont Northeastern University Creighton University University of Rhode Island 4

5 Data Description and Cruise Narrative This cruise report describes the data collected during SSV Robert C. Seamans cruise S-210 between March 27 and May 3, The ship departed from Honolulu, Hawaii, with port stops on Palmyra Atoll and Kiritimati Island, Republic of Kiribati, before finishing the six-week cruise in back in Honolulu, Hawaii (Fig. 1). The bulk of the work conducted during the cruise took place during twice daily research stations consisting mostly of hydrocasts in combination with plankton tows performed with a combination of meter net and neuston net tows. All told, 82 discrete deployments were done on 50 stations. CRUISE TRACK OF S210: Figure 1. Cruise track of Robert C. Seamans cruise S210 between March 27 and May 3,

6 Cruise Narrative The major oceanographic feature along the cruise track is the equatorial upwelling zone, surrounded on the north and south boundaries by the respective north and south subtropical gyres. This provided many large points of contrast on all fronts of our sampling efforts. In regard to the El Ninõ / Southern Oscillation (ENSO) cycle, the central Pacific was in ENSO neutral condition for the duration of the Boreal spring of Departing from Honolulu we were treated to very favorable wind and seas, and made a very speedy transit to the Palmyra Atoll. The sea conditions allowed for an easy training period to get the student body quickly trained on both ship handling and the procedures involved in hydrographic research stations, and so facilitated a smooth and effective start for the program. During this leg, we towed on a daily basis a hydrophone array brought on board by visiting scientist Dr. Simone Baumann from the Scripps Institute of Oceanography for the purposes of mapping dolphin populations along our cruise track. The skills acquired in the first six days were tested as we crossed the ITCZ on our way to our first island stop in Palmyra. ITCZ in these waters generally features squally weather and highly variable winds, but we were treated to an easy passage on our way south. Indeed during our port stop on the wet Palmyra Atoll, the weather for us was very favorable. We were hosted there by both the personnel from the National Fish and Wildlife Service and the Nature Conservancy, the former managing the protected area around the atoll as well as most of the islets making up Palmyra while the latter manages the largest island where we were able to explore the tropical terrestrial environments. During our three-day stop we were able to admire the birdlife of the island as well as conduct some educational snorkeling trips to look at the spectacular coral reefs Palmyra has to offer. On approach to Palmyra, we helped Simone Baumann and Xavier Mico to recover an acoustically triggered recording hydrophone buoy, an extension of Dr. Baumann s research program, and it is here where we said our grateful goodbyes to both of them. The objective of the next leg was to gain an accurate measure of the Equatorial Undercurrent. Though we had early problems with the ship s gyro compass producing the all-important accurate heading data for the on-board Acoustic Doppler Current Profiler (ADCP), these problems were resolved and we succeeded on collecting a good snapshot of this complex current system down to our southernmost point at 1.5 S. Of course prior to turning around and heading back up North, we had to cross the equator where we celebrated the event with a proper visit from King Neptune to induct the first-time crossers into the cadre of veteran Shellbacks. The strength of the EUC as measured by our ADCP was typical for the season and the ENSO conditions at about 1.3 m*s -1, or just over 2 knots. Equally typical were the measurements of chlorophyll a concentrations 6

7 between the minimum surface values of 0.1 µg*l -1 and the highs of 0.8 µg*l -1 in the chlorophyll a maximum layer. The Northbound leg featured the second island stop of the cruise, this being the large atoll of Kiritimati belonging to the Republic of Kiribati. With a population of some 7000 people, the island is located south of the ITCZ for most of the year and consequently has much drier climate than Palmyra only some 200 miles further North. During our three-day port call there, we visited the Saint Francis High School, where we were treated to a fantastic musical welcome and taught a traditional musical play involving a chant and the rhythmic striking together of sticks between rows of participants facing each other. The I-Kiribati students out sang and outperformed us at each turn, but were incredibly graceful hosts, and we were all too happy to have the opportunity to host them in turn on our ship. Hoisting of sails, ship tours and lab demonstrations went some way to help us repay for the hospitality we were shown. Five days after departing Kiritimati for Honolulu for the last leg of the cruise, and shortly after 8 N, much of the effort started shifting toward data analysis and writing by the students at the expense of gathering more samples. This gave the students time to prepare for a poster presentation of their results, which was done as we passed the leeward side of the island of Hawaii. We celebrated the successful completion of the cruise anchored off the west end of Molokai on May the 2 nd, before transiting across the Molokai Channel to Honolulu Harbor where the students and crew of S210 disembarked. All of the student projects began during the shore component gathered the necessary data and succeeded in evaluating their hypotheses. Of course not everything went exactly as planned, as fieldwork in the high seas always manages to throw some surprises ranging from surprising oceanic conditions to equipment failure. Through it all the students worked diligently and hard, and it was this character together with the good humor present in the class that made this cruise a resounding success. This report summarizes the physical, biological and chemical properties measured during the cruise. Physical and chemical data was derived from hydrocast stations (Table 2), while the surface ocean biological characteristics (Tables 3 and 4) were derived from Neuston and Meter Net data. CTD and ADCP data are summarized in figures 3 through 5, while the flow-through data is summarized in Fig. 2. The lengthy CHIRP data is not part of this report. All unpublished data can be made available by arrangement with the Sea Education Association (SEA) data archivist (contact information, p. 2). The information in this report is not intended to represent final interpretation of the data and should not be excerpted or cited without written permission from SEA. 7

8 Figure 2. Salinity, Temperature, and Chlorophyll a Fluorescence Hourly Observations. Measurements of underway flow-through system, 60-minute averages plotted. The missing values from the return leg between 13 N and 21 N are due to computer-related data loss.

9 Figure 3a. Salinity and Temperature sections, Southbound leg from Honolulu to 1.5 S latitude. CTD (SeaBird Electronics SBE 19+) Salinity (top) and Temperature (bottom) profiles plotted on a N/S projection. Data comes from all combined hydrocast and CTD station, vertical lines represent stations, and intermediate data has been interpolated. See Fig.1 for cruise track map, and Table 1 for station locations. 9

10 Figure 3b. Salinity and Temperature sections, Northbound leg from 1.5 S to N 8 latitude. CTD (SeaBird Electronics SBE 19+) Salinity (top) and Temperature (bottom) profiles plotted on a N/S projection. Data comes from all combined hydrocast and CTD station, vertical lines represent stations, and intermediate data has been interpolated. See Fig. 1 for cruise track map, and Table 1 for station locations. The figure includes all CTD casts performed on the Northbound leg with the exception of the last two stations adjacent to the Hawaiian Islands, omitted because of the geographical distance to the rest of the stations. 10

11 Figure 4a. Chlorophyll a Fluorescence (top) and Dissolved Oxygen (bottom) sections, Southbound leg from Honolulu to 1.5 S latitude. CTD-mounted in situ profiles plotted on a N/S projection. Chl a data (uncalibrated SeaPoint fluorometer (µg chl a*l -1 ) comes from night stations only to eliminate diel variation. Oxygen data (ml*l -1, SeaBird Electronics SBE 43 in situ oxygen probe) comes from all combined hydrocast and CTD stations. Vertical lines represent stations, while intermediate data has been interpolated. See Fig. 1 for cruise track map, and Table 1 for station locations. 11

12 Figure 4b. Chlorophyll a Fluorescence (top) and Dissolved Oxygen (bottom) sections, Northbound leg from 1.5 S to 8 N latitude. CTD-mounted in situ profiles plotted on a N/S projection. Chl a data (uncalibrated SeaPoint fluorometer (µg chl a*l -1 ) comes from night stations only to eliminate diel variation. Oxygen data (ml*l -1, SeaBird Electronics SBE 43 in situ oxygen probe) comes from all combined hydrocast and CTD stations. Vertical lines represent stations, while intermediate data has been interpolated. See Fig. 1 for cruise track map, and Table 1 for station locations. The figure includes all CTD casts performed on the Northbound leg with the exception of the last two stations adjacent to the Hawaiian Islands, omitted because of the geographical distance to the rest of the stations. 12

13 Figure 5. Acoustic Doppler Current Profiler measurement summary. Top, southbound leg from 16 N to 1.5 S, bottom northbound leg from 1.5 S to 8 N. Continuously collected East and North velocity components plotted on a N/S projection. Missing data due to failure of the gyrocompass heading sensor. See Fig.1 for cruise track. 13

14 Table 1: Oceanographic sampling station locations Label HC/CTD denotes a combined hydrocast and CTD cast, CTD denotes a CTD cast. Station number Date Local Time Lat E Lon N Depth (m) CTD and Hydrocast stations S CTD 3/28/07 15: S CTD/HC 3/29/07 8: S CTD/HC 3/30/07 8: S CTD/HC 3/30/07 20: S CTD/HC 3/31/07 8: S CTD/HC 3/31/07 20: S CTD/HC 4/1/07 8: S CTD/HC 4/1/07 20: S CTD/HC 4/2/07 8: S CTD/HC 4/2/07 20: S CTD/HC 4/3/07 8: S CTD/HC 4/3/07 20: S CTD/HC 4/4/07 8: S CTD/HC 4/4/07 20: S CTD/HC 4/8/07 20: S CTD/HC 4/9/07 8: S CTD/HC 4/9/07 20: S CTD/HC 4/10/07 8: S CTD/HC 4/10/07 20: S CTD/HC 4/11/07 8: S CTD/HC 4/11/07 20: S CTD/HC 4/12/07 8: S CTD/HC 4/12/07 20: S CTD/HC 4/13/07 12: S CTD/HC 4/13/07 20: S CTD/HC 4/14/07 8: S CTD/HC 4/14/07 21: S CTD/HC 4/15/07 8: S CTD/HC 4/15/07 20: S CTD/HC 4/16/07 8: S CTD/HC 4/16/07 20: S CTD/HC 4/20/07 21: S CTD/HC 4/21/07 8: S CTD/HC 4/21/07 21: S CTD/HC 4/22/07 8: S CTD/HC 4/22/07 21: S CTD/HC 4/23/07 20: S CTD/HC 4/24/07 8: S CTD/HC 4/28/07 8:

15 Station number Date Local Time Lat E Lon. N Depth (m) CTD and Hydrocast stations, continued. S CTD/HC 4/29/07 9: Zooplankton Net Tow Locations. Station number Date Local Time Lat. E Lon. N Depth (m) Label NT denotes Neuston Net Tow, MN denotes Meter Net Tow, NT/MN a combination of the two. All MN tows are oblique tows to 200m depth, NT tows are surface tows. S NT/MN 3/29/07 21: S MN 3/30/07 15: S NT/MN 3/30/07 22: S NT/MN 3/31/07 22: S MN 4/1/07 10: S NT/MN 4/1/07 21: S NT/MN 4/2/07 22: S MN 4/3/07 10: S NT/MN 4/3/07 22: S MN 4/4/07 10: S NT/MN 4/4/07 21: S NT/MN 4/8/07 22: S MN 4/9/07 10: S NT/MN 4/9/07 21: S MN 4/10/07 10: S MN 4/10/07 21: S MN 4/11/07 10: S NT/MN 4/11/07 22: S MN 4/12/07 9: S NT/MN 4/12/07 21: S MN 4/13/07 14: S NT/MN 4/13/07 21: S MN 4/14/07 10: S NT/MN 4/15/07 22: S MN 4/16/07 10: S NT 4/16/07 20: S NT 4/20/07 21: S MN 4/23/07 9:

16 Table 2. Hydrocast Data Summary See Table 1 for station location information. Blank space indicates no data collected. Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 16

17 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 17

18 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 18

19 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 19

20 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 20

21 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 21

22 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S NA S S S S S S S S S S S S ph 22

23 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 23

24 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) Chl a (ug*l -1 ) S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S ph 24

25 Station No. Depth (m) Temp ( C) Salinity (psu) PO 4 (um) S S S S S S Chl a (ug*l -1 ) ph 25

26 Table 3. Neuston Net Data Summary See Table 1 for station location information. Station number Tow Distance (m) Zoop. Biovolume (cm 3 ) Zoop. Density (cm 3 *m -2 ) S S S S S S S S S nd 15.0 nd S S S S S S S S S

27 Table 4. Meter Net Data Summary See Table 1 for station location information. All tows are oblique tows to 200 meters depth. Station number Tow Distance (m) Zoop. Biovolume (cm 2 ) Zoop. Density (cm 3 *m -2 ) S S S S S S S S S S S S S S S S S S S S S S S S S S

28 Table 5: Student research projects, Cruise S210 Title The effect of Equatorial Upwelling on surface sea water ph in the central tropical Pacific. The ReletiveRelative population of chaetognaths in the mid-pacific Investigation of the use of Apparent Oxygen Utilization as a Tracer for Water Masses in the Equatorial Pacific. The effects of sea water ph on the distribution and abundance of pelagic Foraminifera in the Equatorial Pacific. A Comparison In Diet Of Myctophids Myctophum Lychnobium And Myctophum Nitidulum In The Central Pacific Ocean. Student Investigators Katrina Barnes and Ana Jamborcic Joshua Bates James Faulkner Haley Kuntz and Adam Scherr Xavier Marvel Diversity, Distribution and Abundance of Dinoflagellates in Relation to the Occurrence of Bioluminescence. The Relationship Between Primary Production and Zooplankton Biomass in the Tropical and Equatorial Pacific. Caitlin O Hern and Julia Gruberg Sergio Perez The Effects of El Ninõ-Souther Oscialltion on Chlorophylla Concentrations in the Eastern Equatorial Pacific. Andrew Sclafani The Relationship Between Zooplankton Biomass and the Extent of Diel Vertical Migration in the Tropical Pacific. Lauren Valentino 28

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