R/V EDWIN LINK 9905
10-29 May 1999
TABLE OF CONTENTS
Purpose of the Cruise 1
Cruise Narrative 1
Individual Reports 3
Appendix. I. Event Log 22
Appendix II. List of Personnel 34
Appendix III. List of Figures 35
Purpose of the Cruise
Acoustic Doppler Current Profiler
DNA Gut Contents Analysis
Video Plankton Recorder (MOCNESS mounted)
Predation of omnivorous copepods
Zooplankton Pump Sampling
Appendix I. Event Log
Appendix II. Personnel List
Appendix III. List of Figures
We gratefully acknowledge the very able assistance provided by the officers and crew of the R/V EDWIN LINK, the University of Miami's Techical Support Group and student volunteers. This report was prepared by Greg Lough, Betsy Broughton, Lew Incze, Cisco Werner, Anna Sell, and Jim Manning. This cruise was sponsored by the National Science Foundation and the National Oceanic and Atmospheric Administration.
Purpose of the Cruise
The objectives of the cruise were to: (1) Examine the potential exchange of plankton in the vicinity of the tidal flank on the southern flank of Georges Bank and in particular how the exchange relates to retention of fish larvae in the well-mixed cap of the Bank; (2) Use circulation model and drifters to predict the tidal excursion for guiding the samping effort, and forcast larval fish trajectories to simmulate feeding and growth in a near realistic prey field using a bioenergetics model; (3) Conduct site studies to determine the vertical distribution of cod and haddock larvae and pelagic juveniles in relation to the tidal front, their diel variability, predator-prey relations, and biochemical content for growth in the different water-column conditions.
The R/V Edwin Link left Woods Hole at 1400 h DST May 10, 1999 with a complement of 20 scientist and headed for the southern flank of Georges Bank to begin the initial Bongo-net survey. Arrived at our first station 37 at 40 45.0', 68 00.0' (70-m depth) at 0300 h May 11 (Note: all times listed in this narrative are local, consistent with the eventlog). We continued east making bongo tows along the 70-m isobath and started our first north-south transect with station 42 at 41 18, 67 16 (55-m bottom depth). Stations on transect were 5 miles apart and transects were 7 miles to the west. The second transect passed along side the Schlitz moorings. Drifters were released on the third transect near bongo stations 58 and 59 on May 12 to bracket the tidal front centered on the 60-m isobath. On the mixed side of the front drifter #395 (13m) was set at 0221 h DST, 41 8.9, 67 30.6 (57m bottom depth); drifter #200 (33m) was set at 0230 h, 41 8.7, 67 30.8. On the stratified side of the front drifter # 234 (33m) was set at 0405 h, 41 2.6, 67 25.0 (64m bottom depth); drifter #393 (8m) was set at same place and time.
The bongo grid, which consisted of 6 transects (Fig. 1a and Fig. 1b) 43 stations (42-84), was completed at 0340 h, May 13. We then steamed eastward to locate the drifters released May 12 and make short transect profiles to determine what water type they were tracking. Drifter #200 (mixed, deep) was located at 41 11.3, 67 39.9. A Seabird CTD model 19 was used here for a profile (station 85). Another profile was taken at 41 5.4, 67 26.2 (Station 86). Drifter #234 was located at 41 5.1, 67 21.6 and a profile was taken (station 87). Arrived at our tidal-front time-series station 88 at 1100 h, May 13 (41 12.5, 67 29.0) and began transect across the tidal front with the CTD. CTD stations were made every 2 miles southeast across the front ending with station 94 at 1400 h (41 1.8, 67 20.5). The center of the tidal front was determined to be at the 60-m isobath, so we went back to 41 9.0, 67 26.0 and started the tidal-front time series of observations at 1545 h begining with 1-m MOCNESS 221. The routine was to sample the same site every 6 h with MOCNESS-1m, CTD, pump, and MOCNESS-10 m while the tide moved back and forth across the fixed site. This routine was followed until 0200 h, May 15 when the four drifters were picked up: #200 (mixed) at 0337 h (41 6.3, 67 41.1), #395 (mixed) at 0420 h (40 59.7, 67 45.1), #393 (strat) at 0635 h (40 56.8, 67 25.0), #234 (strat) at 0720 h (40 55.9, 67 25.1). We then steamed back to old station 95 to begin a 8-station CTD transect across the tidal front. Station 98 started on the south side at 0815 h (41 0.3, 67 19.7)) and ran northwest to the shoal station 105 which was completed at 1355 H (41 12.5, 67 29.0). Talked to R/V Endeavor earlier in the morning and planned to redevouz to pick up formalin and exchange data. At 1440 h the Edwin Link launched the 23' Willard and took 9 scientists to the Endeavor at 41 5.73, 67 12.36. At 1600 h Edwin Link steamed back to the transect line and began a new station 106 time series on the stratified side of the tidal front (65 m) at 41 2.0, 67 21.2. A 1-m MOCNESS was deployed at 1706 h May 15 followed by the regular series of samplers.
Radio call to Endeavor at 0830 h May 16 to discuss preparations for surface dye release experiment at 1300 h today. Steamed north on transect to find tidal-front drop in temperature to set drifters initially on the mixed side of the front. Drifter #089 (23m) and drifter #087 (13m) set at 1100? h in 47 m water depth (41 13.3, 67 27.5). Steamed south to 62 m, stratified water, and set drifter #393 (33m) and #093 (8m) at 1215 h (41 4.1, 67 21.6). Each drifter site was immediately followed by a SeaBird profile. At the stratified site deployment a Reeve net tow was made for live copepods. We returned to station 106 (65 m) at 1330 h and resumed our 6-h time series of observations at a fixed site beginning with MOCNESS 236. Continually plagged by loss of power to MOCNESS-10m. Completed 48-h time series at station 106 at noon May 18. Moved to station 100 on the 60-m isobath (41 5.6, 67 23.7) and began series of observations. MOCNESS-10m not working. Between 1600 and 1800 h steamed north on transect to find front by temperature signature. Returned to station 100. Two more drifters were put out at the 60-m isobath May 19: drifter #234-B (13m) at 0408 h (41 7.9, 67 20.5) and drifter #200B(25m) at 0510 h (41 6.8, 67 19.7).
May 20, two drifters on the mixed side of the front were recovered: drifter #87 at 0430 h (41 10.3, 67 40.6); drifter #89 at 0600 h (41 1.7, 67 30.5). Sampling continued on station 100 at 0715 h but swell prevented use of the MOCNESS-1/4m. MOCNESS-1m and pump/CTD continued throughout the day. Ceased operations midnight to 0600 h May 21 due to high winds, 40-50 knots and swell. Manning began drifter recovery. Drifter #200B recovered at 0630 h (41 2.4, 67 30.8); drifter #234B recovered at 0740 h (40 59.6, 67 35.14, 65 m); drifter #093 recovered at 100 h (40 54.9, 67 39.1, 67 m); drifter #393 recovered at 1710 h (40 57.6, 67 23.2, 74 m), no transmitter. Tried to start CTD nutrient transect at 2100h but electrical cable problems from CTD winch delayed operations.
Started 8 station CTD nutrient transect at 0142 h May 22 on former station 98 (41 0.0, 67 19.6, 71m). Ended CTD transect at 0702 h at station 105 (41 12.5, 67 28.9, 44m). On stratified side of front, the storm had mixed the warm surface water down so that a weak thermocline (8-7 C) was now at about 15 m. Radio call 0830 h with Endeavor and Oceanus discussed setup for dye injection experiments at thermocline and bottom on stratified side of front to begin near noon. Endeavor will be located at 67 20, Elink at 67 22, and Oceanus at 67 24. Elink set out drifter #87B (13m) at 1012 h about one mile west of central mooring (41 6.8, 67 17.8, 59.3m). Drifter #234 (8m) and drifter #200C (33 m) set out on the stratified side at 1609 and 1615 h (41 3.1, 67 22.1). Endeavor delayed pycnocline dye injection until tomorrow. Elink began a new time series of observations at former station 106 (65 m) with MOCNESS 263, 1800 h, May 22.
May 23: time series continues on station 106, glassy sea, hazy fog. Radio call with Endeavor and Oceanus. Endeavor will inject dye around noon in pycnocline only further to the west near 67 38. Willard launch at 1330 h to Oceanus confer with Houghton and bring back jars. Finished station 106 at 1940 h May 24 and steamed west to find drifters in building storm. Retrieved drifter #200C at 2150 h (41 2.3, 67 30.8, 62m); drifter #234C at 2247 h (41 2.4, 67 27.9, 61m); drifter #087B at 0028 h May 25 (41 6.4, 67 29.1, 56m). High winds (30 kt) and seas curtailed operations for the morning of May 25. CTD/nutrient transect of 7 stations began half mile west of Schlitz moorings at 1120 h, Station 14 and ended with station 120. We then steamed back along the transect looking for the front (<8.6C) and deployed drifter #89C (13m) at 1743 h (41 9.2, 67 21), drifter #87C (33m) at 1746 h , and drifter #274C (33m) at 1858 h (41 6.6, 67 17.8), and drifter #93B (8) at 1900 h.
Returned to station 100 (41 5.5, 67 22) at the 60-m isobath and began a time series of observations beginning with MOCNESS 275. Completed a 48-h time series at station 100 by midnight May 27 and steamed north to station 95 (55 m) for a short 12-h series of tows beginning in the early hours of May 28. A situation developed where a crew member needed to fly home for a seriously ill family member, so we left station 100 at the end of MOCNESS 293, 1030 h May 28 and retrieved drifters. Retrieved drifter #0893 at 1118 h (41 8.2, 67 25.9, 56m); drifter #0873 at 1128 h (41 9.7, 67 24.1, 54m); drifter #93C at 1200 h (41 7.6, 67 23.0, 58m); drifter #234 at 1245 h (41 4.2, 67 24.7, 62m). The final activity was a CTD/nutrient transect of 3 stations (115-117) across the tidal front from 40 58.4, 67 18.9 (73m) to 413.9, 67 21.2 (63 m) which was completed at 1545 h May 28. We left Georges Bank and returned to Woods Hole at 0800 h May 29.
Physical Oceanography (J. Manning and K. Fisher)
A total of seventeen drogued-drifter deployments were made on this cruise in four different clusters (see Table 1) Clusters 1 and 2 are shown in Figure 2 and 3 and 4 in Figure 3. The drifter ID, listed in column #1 below, is coded by ARGOS PTT# followed by an integer that represents the consecutive deployment. The deployment ID "3951", for example, is the first deployment of PTT#395 on this cruise. The dimension and configuration of the drifters and drogues are described in our earlier cruise reports such as SJ9503.
Drifters were deployed on either side of the tidal front and at different depths for each of the cluster experiments. Cluster #1, for example, had two drifters on the mixed side with drogues at 13 and 33m, respectively, and two drogues on the stratified side at 8m and 33m, respectively. In the case of cluster #2, additional drogues were placed in the vicinity of the front. Each of the cluster experiments were conducted for 3-4 days. Drifters were then recovered and redeployed relative to the tidal front. The tidal front structure was determined by a CTD section prior to each cluster deployment.
Preliminary analysis of these cluster deployments do not indicate clear preferential movement relative to the front. There was evidently a surface DIVERGENCE at the front in the first cluster, a CONVERGENCE in the 2nd, neither in the third, and a strong VERTICAL shear in the fourth. Several months of analysis will be necessary to distinguish the important forcings for each cluster. While they were deployed in nearly the same geographic region, the wind and density fields changed significantly between deployments. Several more model runs with various inputs will be conducted in the case of each cluster to help define the mechanisms involved.
Table 1. EL9905 Drifter Deployment Log
Karen Fisher made a significant contribution to the real-time display and archiving of alongtrack data. She wrote a series of Perl, FTP, and MATLAB scripts to handle the hull mounted sensor data . By mid-cruise, plots of all the important variables (SST, true wind, ship track, etc.) were displayed on both an SGI and LINUX machine in the main lab.This was particularly helpful during the periods of drifter deployment operations when it was necessary to locate the position of the seasurface temperature front. The real time meteorologic data was helpful for validating of model weather data. Towards the end of the cruise we were able to use Karen's processed data to make shipboard heat flux estimates. Her write-up follows.
The alongtrack data gathered by the R/V Edwin Link's underway system show strong fronts in temperature and salinity over the course of the cruise (Fig. 4, mayat130.tif). Abrupt temperature excursions of up to 6 degrees were observed, sometimes concurrently with salinity changes. The over all pattern shows the advection of a warm patch (average temperature of about 12 degrees C) through the study region between days 135 and 140, with a return to the colder (8-10 degrees C) water following the main patch. A large excursion in the fluorescence measured was also observed; however it should be taken with reservations as it was confounded by a flow problem experienced at the time the drop in fluorescence was seen, and because it registered near- saturation for the majority of the cruise. A major wind event, predicted by the data assimilation team, was observed to arrive at the ship just before midnight GMT on Day 140 (days measured from January 1st =0). The wind shifted rapidly at the onset, then proceeded to turn 180 degrees in time to blow over 20 knots (subsampled hourly) once again on Day 144. The wind events coincided with a precipitous drop in both barometric pressure and air temperature (Fig. 5, mayatmp130.tif). Both the short wave and long wave radiation sensors seemed to be operational, and short wave radiation matched well with the model prediction under preliminary scrutiny.
As the ship spent the majority of the cruise keeping stations bordering the tidal front, temperature and salinity are plotted in relation to the predicted tidal velocity for each tidal period (Fig.6a (maytide6.tif) , Fig.6b, maytide12.tif, Fig.6c (maytide18.tif) , Fig.6d (maytide24.tif) , Fig.6e (maytide30.tif), and Fig.6f maytide35.tif) [Note that the tidal velocities (Fig.7, maytidv130.tif) used in these plots are derived from Candela's estimates based on previous GLOBEC ADCP data]. Tidal velocity curves which depart markedly from neat ellipses indicate periods of rapid ship motion (buoy collection or transits). Tidal ellipses which are found in conjunction with circular T and S plots indicated stations well within a water mass, and no change in water mass through advection during the tidal period, such as tidal period 13. Unidirectional spirals in temperature and salinity indicate advection of a water mass through the study region that is not primarily tidal in origin, seen in tidal period 7 which marked the beginning the intrusion of the warm water patch. Finally, there are symmetric variations that are indications of the tidal front being advected past the ship, exemplified by tidal period 19. In this period, cooler water is initially advected past the ship, off Bank. Warmer water from beyond the front then surrounds the ship as the tide turns westward, and then returns towards the Bank, once again bringing the highly variable, but cooler, frontal waters past the ship. As the tide reaches it's maximal on Bank extent, warmer, uniform water surrounds the ship, until the front is once more advected past as the tide flows off Bank again.
Acoustic Doppler Current Profiler
After a visit from Charlie Flagg in late April (prior to our May cruise ), the narrow band 150kHz ADCP was configured properly. The problem we had on the April cruise did not have to do with the ADCP itself but rather with the string of GYRO heading and GPS information being fed to the ADCP computer. During the later part of the May cruise, however, we had a similar problem where the heading was not getting to the ADCP computer at all. After the May cruise, Noah, the shipboard technician, found a loose circuit board in the ADCP deck box which is located down in the hold. After securing that unit, the heading returned and, at the time of this writing is apparently ready for the June cruise.
Despite these problems, we did collect good data for the first half of the May cruise. The raw pingdata files were processed with Flagg's MATLAB routine "realtime.m" and, after iteratively determining a transducer correction angle of 5.2 degrees, output in the form of model ready ".m3d" files were generated. In order to reduce the high frequency not important to the model runs, a one hour running average was conducted in the final processing step. Plots of the data were made in the form of contoured (Fig.8a) velocity, time series (Fig.8b) of u & v velocity, and vector (Fig.8c) plots.
A total of 164 CTD casts were conducted (71 Seabird Model 19 and 93 Seabird Model 911). The Model 19 CTD was attached to the Bongo Net wire during several transects across the southern flank in the first few days of the cruise. These vertical sections revealed the very thin surface layer (Figure 9) which extended far up on the bank (~45m water depth). It gradually tapered to zero when we reached the area of sand waves. These initial transects help define the appropriate drifter deployment locations and drogue depths. In the case of the stratified side of the front, for example, the tether was shortened in order to center the most of the drogue within the thin surface layer (8m).
Several horizontal contour plots including the station locations (Fig. 1), surface and bottom temperature (Fig.10a), surface and bottom temperature anomaly (Fig. 10b), surface and bottom salinity (Fig. 10e), and surface and bottom salinity anomaly. Cross-sectional views of temperature (Fig. 10e), salinity (Fig. 10f), and sigma-t (Fig. 10g) demonstrate the degree of along-bank variability in the cross-bank structure. Notice the off-shore influence appears in transect 1, is non-existent in transects 3 and 4, and then reappears in the last transect 6. The offshore influence (mini-intrusions at depth) is also evident in some of the horizontal figures above.
In order to examine the vertical structure as observed at various times and positions by the Model 911 CTD, individual profiles were plotted together on the same scale in batches. The first batch (cast 1-30: Fig.11a), for example, shows very little structure in the first dozen or more cast. Beginning with cast#15, a surface layer ranging from 1-15m depth was evident. The other two batches (Fig. 11b: cast 31-60 and Figure 11c:cast 61-89) show similar variation with time and locations. Similarly, plots of fluorescence and density profiles were made in Figures 11d (cast 1-30), 11e (cast 31-60), and 11f (cast 61-89). While lacking detail, these figures provide some indication of which casts detected a strong pycnocline and subsurface fluorescence maximum. Note that over the course of time, as we visited different sites at different phases of the tide, the surface layer varied from almost 20m to near zero. The corresponding profiles of light and light transmission are presented in Figure 11g (cast 1-30), Figure 11h (cast 31-60), and Figure 11i (cast 61-89) (As of this writing, I do not know what to list as the units of the Par sensor. There are two additional variables in the data file called "surface Par" and "corrected Par"). Cross-sectional views of temperature (Fig. 12a), salinity (Fig.12b), sigma-t (Fig12c), and fluorescence (Fig.12d) demonstrate the large degree of change in the water mass structure over the period of the cruise. This is particularly true for the case of transect #1 vs. transect#2 which were conducted only a few days apart. The near surface layer developed quickly.
In order to determine the timing of biological sampling relative to tidal phase, plots were generated during the cruise which a) overlaid tidal velocity vs. haul times (Fig. 13a) and b) binned hauls times vs. tidal direction (Fig. 13b). This provided a means of assessing which phases of the tide were sampled sufficiently.
An automated perl script was operating each afternoon on a NMFS SGI machine which conducted a FTP session into the CMAST imagery archive. If any new CLEAR images were available, a MATLAB routine was launched to plot the zoomed-in image of our study area and a decoded gif image was emailed to the ships. Bathymetry and mooring locations were overlayed on the image for referencing. While many images were still too cloudy to be useful, some of them such as those on May 10, May 15, May 17, and June 5 (Figs. 14a-d) indicated a complex structure on the southern flank which did help in diagnosis of our shipboard observations. When we returned home at the end of May, the zoomed viewport was extended to include the Northern Flank for the benefit of the ENDEAVOR and OCEANUS studies in that area. The daily Limeburner drifter locations were then overlayed as well. These region-specific images are helpful to see the small scale features. To see the big picture with ring activity offshore, CMAST generates their own set of gif files. These are also clear for same May 10, May 15, May 17, and June 5 dates listed above.
Real-Time Circulation Modeling (C. Werner and J. Manning)
An extensive report of the EL9905 modeling activity is available at http://www.opnml.unc.edu. After a short "cruise log" section, the postscript file includes a cronological account of each run. The text includes detailed listings of input files to document/archive the various experiments that were conducted on-board so that they may be rerun in the future. The electronic files for each run are also stored at the UNC site. Diagnostic plots include results of each QUODDY model iteration, boundary elevations, and particle trajectories. These were generated and saved for each run. Example plots were presented in our previous cruise report from EL9904. A condense summary of the report is presented here to describe the basic tasks perform at sea. Due to the complexity of the real-time system (Figure 15 and 16), readers are referred to both the UNC and Dartmouth Site: (http://www-nml/dartmouth.edu) for a more detailed description of the model process.
Our first successful runs were made a few days into the cruise on May 11-12. Beginning with the hydrography available from the previous broadscale cruise (OC341) and modeled forcing files (wind & boundary elevations) arriving from UNC, the experiments were underway. In the following few days a series of test were made using updated hydrography from the recently completed bongo survey as well as shipboard estimates of wind and heat flux. As reported in a May 17-18th email to our colleagues on land, the results were encouraging. The "separation distance" (the difference in the observed vs. modeled drifter location calculated for each run) was reduced from ~4.5 to less than 2km as we incorporated more real forcings.
Sensitivity studies on the degree of vertical mixing were also conducted during this time by altering the value of the coefficient "ekmin". The objective of the parameter change was to capture the very thin surface layer observed on most CTD cast. A reduction to 2 x 10-5 m2/s accomplished the task but, as with all of these experiments, extensive hindcast studies will be necessary to determine the correct parameterization..
After another set of forecast on May 20th, a few days were spent writing code to animate cross-bank particle trajectories. On request by the chief scientist, movies were generated to illustrate the modeled advection. The code was passed on to our Endeavor colleagues who were developing one of their own.
A few days later, after "May24_FCAST2", we were also able to show some improvement due to assimilation of ADCP data. In this case we had received additional ADCP data from the Endeavor colleagues. In subsequent days we also receive some of their observed drifter and hydrography data. Initial condition files were generated from their VPR surveys ("grid2" and "grid3").
As reported in our May 23-24 email to the land-based team, the hydrography from the AL9904 was received and incorporated into our initial condition files. Thanks to Maureen Taylor on board that vessel, we received 27 CTD cast from the Southern Flank as they sailed in the vicinity of our investigation. An update of several more cast was received a few days later, as they neared completion of their bank-wide coverage. That update was incorporated into the initial condition file for the ENDEAVOR runs the following week.
A 3-day briefing (Sept. 1999) was conducted with the entire set of "real-timers" to discuss our effort, evaluate the results, and plan for the future. At the end of this workshop documents were produced to address the issues of both technology transfer and the hindcasting plan. These documents were posted on the Dartmouth RTDA site along with the draft manuscript for EOS.
Bongo-net Sampling (G.Lough, M.Kiladis, E.Broughton)
Fifty-one bongo tows were made with a 61-cm frame fitted with 333 and 505 mesh nets using standard MARMAP procedures; i.e., double-oblique from surface to within 5 m of the bottom. A SeaBird CTD (Model 19) was attached to the towing wire above the bongo to monitor sampling depth in real time and to record temperature and salinity. The 505 net sample was sorted at sea to provide counts of cod and haddock eggs and larvae (Figure 1b). Larvae removed from the bongo-net samples were individually frozen in liquid nitrogen for biochemical analysis ashore or preserved in ethanol for otolith aging.
MOCNESS Sampling (G.Lough, E.Broughton, M.Kiladis)
The 0.25-m2 MOCNESS with nine 64 mesh net sampled phytoplankton and microzooplankton. A total of 11 hauls were taken. The tow profile for the 0.25-m2 MOCNESS was nominally 10-m strata within 5-m of the bottom. The nets typically sampled for 3 minutes to filter about 35 m3 of water.
The 1-m2 MOCNESS with nine 333 mesh nets was used to sample larval fish and larger zooplankton. A total of 41 hauls were taken. Sensors on the 1-m2 MOCNESS included downwelling light, fluorometry, depth, temperature, and salinity. A Video Plankton Recorder (VPR) was attached to the 1-m2 frame to record fine-scale zooplankton distribution during the tow. The VPR high magnification camera was set to a field of view of 2.5 x 3.0 mm and the low magnification camera captured a 2.0 x 2.5 cm area. The tow profile for the 1-m2 MOCNESS was nominally 10-m strata within 5-m of the bottom; extra nets were used for special collections. The nets typically sampled for 5 minutes to filter about 250 m3 of water.
The 10-m2 MOCNESS with five 3-mm mesh nets sampled juvenile ichthyoplankon and larger zooplankton predators. A total of 17 hauls weretaken: four from the "mixed" or shoal side of the tidal front, seven from the stratified or off-bank, southern side of the tidal front, and four hauls within the tidal front. The tow profile for the 10-m2 MOCNESS was nominally 10-m or 20-m strata within 5-m of the bottom. The nets typically sampled for 10 minutes to filter about 5000 m3 of water.
The MOCNESS sampling strategy was to make four 1-m2 tows every 24 hours at 0600h, 1200h, 1800h, and 2400h. The plankton from the first down profile would be preserved in formalin for larval gadid gut content analysis and gear comparison studies. Two nets were sampled from the surface to 20-m and from 20-m to the bottom to be sorted at sea for gelatinous zooplankton counts, biochemical specimens, and special samples. The remainder of the latter two nets was discarded. 0.25-m2 MOCNESS tows were made between 1m2 tows in conjunction with pump sampling. All samples were preserved immediately in formalin for taxonomic identification, prey field analysis, and gear comparison studies. 10-m2 MOCNESS hauls were taken between 1-m2 tows. Gelatinous zooplankton was visually counted then samples were preserved in formalin. 10- m2 plankton samples will be used for predator studies and juvenile gadid gut content analysis.
Table 2a and 2b documents the repository of samples from MOCNESS and BONGO nets, respectively.
Special Collections (E. Broughton, E. Caldarone)
Samples for biochemical and age analysis were taken from fifty one 505 and 333 , 61-cm bongo nets, and forty one 333 mesh 1-m2 MOCNESS hauls. All samples were rinsed from the nets using minimal seawater pressure and transferred to buckets containing ice packs. Plankton from nets that were not to be sorted was preserved immediately using 4% buffered formaldehyde in seawater. Plankton samples sorted for fish or invertebrates were picked in seawater filled translucent sorting trays on ice covered light tables. Every effort was made to keep samples cold during processing to delay decomposition. Samples taken for biochemisty (Buckley) were video taped for later measurement using a Zeiss Stemi SV 6 stereomicroscope equipt with a MTI CDD72 high resolution black and white video camera then individually frozen in liquid nitrogen. Larval gadids taken for otolith analysis (Burns, Townsend) were preserved in 85% EtOH.
Table 2a. BONGO Sampling # of specimens.
|Number of Jars||58||52|
Table 2b. MOCNESS Sampling # of specimens
|Number of jars 0.25m2||0||11||11||11||10||11||10||0||0|
|Number of jars 1-m2||0||53||53||56||68||95||138||0||0|
DNA Gut Content Analysis (E. Horgan)
A total of 63 individuals predators from 5 invertebrate and four fish taxa were preserved in 95% ethanol for later analysis for the presenceof Calanus, Pseudocalanus, cod and haddock DNA in the stomach contents.
MOCNESS-Mounted Video Plankton Recorder (G.Lough, E.Broughton)
The Video Plankton Recorder, an underwater imaging video microscope, was mounted above the net opening on the 1-m2 MOCNESS. This particular system was held in four underwater housings and consisted of two Hi-8 Video Camcorder interfaced with Tattletale computersoftware and Horita time code generators, low (5.6x) and a high (72x) magnification cameras, a strobe, and a 24V-8amp Gel battery pack. Operation was independent of the MOCNESS. Recordings were later dubbed to SVHS tape format together with time code. Recordings were made for twenty five of forty one 1-m2 hauls. Problems with battery charging and a ship's brownout caused communication short circuit prevented taping during all MOCNESS deployments. All in-focus images will be identified to the lowest taxon possible in the laboratory. Processing will include hand identification with computer assisted focus detection, measurement, and 3-D orientation.
Biochemistry (E.Caldarone, J. Burns)
As previously described in the special collections section, a total of 3,189 cod and haddock larvae were collected for biochemical analysis from the bongo-net survey hauls and extra net profiles of the 1-m2 MOCNESS hauls. Species distribution was 34% cod, 66% haddock. The larvae will be analyzed for their RNA, DNA, and protein content and the data used to determine the growth rate and nutritional condition of the individual fish. A comparison will be made of fish taken from the different sites and at discrete depths. A subsample of 232 larvae will be shipped to Dr. Mike St. John at the Danish Institute for Fisheries Research for lipid analysis.
Predation of omnivorous copepods on early developmental stages of Calanus finmarchicus and Pseudocalanus spp. (Anne Sell (WHOI), Jenifer Austin (WHOI) & Grace Klein-MacPhee (URI))
(1) To catch and maintain cultures of several species of omnivorous copepods that are abundant and potentially important as predators of early life stages of Calanus finmarchicus and Pseudocalanus spp.
(2) To catch adult female C. finmarchicus and Pseudocalanus spp. for cultures producing eggs and nauplii to be used in predation experiments.
(3) To run predation experiments at ambient sea water temperature using deck incubations in a plankton wheel.
We started collecting live copepods from G. Lough's bongo net hauls on May 11-13, simultaneously with the sorting of fish larvae. In addition, we took a vertical hauls with a Reeve net on May 12 ,16 , 22 and 27. We collected the adult females of Calanus and Pseudocalanus (to obtain eggs and nauplii as prey) and of Centropages typicus, Metridia lucens and Temora longicornis (predators). Because most copepods and particularly the adult Calanus were in better condition when collected with the Reeve net, we obtained the majority of experimental animals from those tows. The abundance of adult female Calanus generally was much lower than during April, with the majority of the population consisting of late copepodid stages. The highest number of adults we found on May 12 at the deeper (80 m) off-bank station.
We held all copepod cultures in a lab incubator at 4 (C, except for the Pseudocalanus cultures, which we kept at 12(C in order to accelerate egg development times. We changed the cultures of Calanus 1-2 times daily to collect eggs to be either used directly in experiments, or to be kept to hatch and provide cultures of nauplii. All other cultures were changed at intervals of several days. Predators were fed ad libitum with phytoplankton from cultures (Thalassiosira weissflogii and Heterocapsa triquetra) before being used in experiments.
We ran one 12-hr and eight 24-hr predation experiments using the combinations of predators and prey listed in the table below. (Experiment numbers are consecutive to those for cruise EN 322 in April/May 1999. Predators in 'Experiment HYD' were hydroids instead of copepods. This experiment was done as part of J. Austin's project within the Summer Student Fellow Program at WHOI.)
Table 3. Copepods Experiments
|XIII||Metridia lucens||Pseudocalanus spp.||nauplii||May22-23|
|HYD||Clytia gracilis||Pseudocalanus spp. andCentropages typicus||nauplii||May 27-28|
All incubations were run at ambient surface sea water temperature, which varied between 8 (C and a maximum of 15 (C over the course of the cruise. For the experiments IX, X, XI and XV, changes in sea water temperature over the 24-hr period of incubation were 1-2 (C. Temperatures varied over 3-3.5 (C in experiments VII, XIII and XIV, and over 5.6 (C in experiment XII. We measured temperatures in the incubators at 1 to 2-hr intervals in order to relate ingestion rates to the average temperature during the respective period of incubation.
We generally worked with 12 or 15 2-L bottles on the plankton wheel, using three replicates each of a control (no predators) and three or four different predation treatments, differing in prey concentrations and/or prey type. For egg-predation experiments, we used eggs that were less than 12 hrs old at the start of preparation for the incubation. This was to ensure that the eggs would not hatch during the incubation (egg development time of C. finmarchicus at 5 (C is 2.6 days). To avoid hatching of eggs after the incubation, in response to the stimuli of light and increased temperature during counting, we preserved the eggs with vinegar directly after terminating the experiment (2 ml to 20 ml of sample; P. Joli pers. comm.). Nauplii were counted live.
As results of the predation trials with omnivorous copepods, we established functional response curves describing prey density-dependent ingestion rates for the three predator species Metridia lucens, Centropages typicus and Temora longicornis feeding on the eggs and nauplii of Calanus or Pseudocalanus. Feeding on Calanus nauplii, ingestion rates (per individual) were similar for all three species of predators over a range of 25-50 nauplii/ L, with rates between 2 and 9 nauplii/ predator * day. Saturation of ingestion rates occurred at higher densities of prey, but in some cases (eg. Centropages feeding on Calanus nauplii) could not even be reached with prey densities of 200 nauplii/ L. Comparing predation at different temperatures, we found that ingestion rates of Metridia decreased with increasing temperatures (6 (C, 9 (C, 13 (C).
The hydroid experiment was a follow-up for the earlier work of L. Madin and coworkers, which has provided evidence that Clytia gracilis hydroids are substantial predators on Georges Bank. Our experiment involved examining hydroid predation on two size classes of Pseudocalanus nauplii and on early stages of Centropages nauplii. Hydroid colonies with ten feeding hydranths each were placed in 1-L jars and incubated for 12 hrs at an ambient temperature of 11 (C. None of the larger Pseudocalanus nauplii were ingested, but predation on different densities of the small Pseudocalanus nauplii and of the Centropages nauplii did occur.
GELATINOUS PREDATORS (Grace Klein-MacPhee Co-PI)
The role of my complement of the predation group in the Georges Bank GLOBEC program is to identify potential gelatinous predators on the target species (cod, haddock, Calanus and Pseudocalanus); to determine their biomass on Georges Bank coincident with the target species; to determine their potential impact on survival of cod and haddock, either directly as predators on eggs and larvae, or indirectly as competitors for their food, Calanus and Pseudocalanus.
In the field studies conducted in 1995- 1999, we identified three abundant species of ctenophores in addition to abundant planktonic hydroids and chaetognaths. I have focused on the ctenophore Pleurobrachia pileus as a predator on the target species because it has been abundant in several years of the survey and because it was described by Bigelow in 1924 as one of the most important pelagic coelenterates in the Gulf of Maine from an economic standpoint because it was locally very abundant, present throughout the year, and was a destroyer of smaller planktonic animals in particular copepods (Bigelow 1927). Bigelow also believed it to be an important predator on cod and haddock eggs although he did not offer any direct evidence of this.
Examination of gut contents from cruises in 1995 showed that fish eggs and larvae including cod were consumed in small quantities (1.25% of diet), and various stages of copepods were consumed in larger quantities (17% Calanus and Pseudocalanus and 15% other or unidentified copepods). We have also determined gut passage times of live Pleurobrachia using dyed Calanus adults as prey at 9oC. Gut contents of preserved specimens from net tows and from diver collected specimens were also determined and will be compared. In general, diver collected specimens had fuller guts that specimens collected in the Moc-1 nets. Ultimately, gut contents and gut passage times will be used to determine prey selection and feeding rates.
There are several species of ctenophores occurring on Georges bank including Bolinopsis, Beroe,and Pleurobrachia . Since gelatinous zooplankters in general are often damaged in net collections, and those which survive relatively intact often break down when exposed to preservatives, it is difficult to obtain abundance data for these organisms by using traditional net collection methods. Identifying and enumerating gelatinous zooplankton by video recording methods is in the developmental stage and will be tested this year. Until this method has been validated, the most useful method for enumerating delicate gelatinous plankton is by counting the samples immediately after they are brought on board before preservation. This is time consuming and is often difficult when there is a great deal of material in the samples, however the more robust specimens (Pleurobrachia) can be counted with reasonable accuracy and the more delicate species (Beroe, Bolinopsis) with a rough approximation since they have a tendency to break into pieces.
Bigelow, H.B. 1927. Physical oceanography of the Gulf of Maine. Bull. U.S. Bureau of Fish. 40(2): 511-1027
In the May 10-28 cruise my goals were:
To describe potential gelatinous predators on the target species (cod, haddock, Calanus, Pseudocalanus) which were present during this cruise with emphasis on the ctenophore Pleurobrachia pileus
To describe Pleurobrachia vertical distribution and abundance both day and night across a tidal front
To count jelly fish and ctenophores collected by bongo nets, MOCNESS-1(MOC-1 and MOCNESS-10(MOC-10)nets before preservation and to compare these counts to selected samples after preservation and storage
To compare the distribution of the target species particularly cod and haddock with the distribution of Pleurobrachia and to determine if there were differences across the front
To obtain samples of Pleurobrachia for gut content analysis
To assist in setting up Copepod feeding experiments conducted by Anne Sell which will contribute to the understanding of the role of small invertebrates as predators on the target organisms Calanus and Pseudocalanus.
Plankton collections were made using a series of nets 1 meter MOCNESS with 9 nets (.333µ mesh) and 10 meter MOCNESS with 5 nets (3 mm mesh)at shallow and deep stations in the day and at night, on either side of the tidal front where cod larvae and Calanus were determined to be present. Nets were fished at 8 depths in the deep stations and 5 depths in the shallow stations. The presence of cod and Calanus was determined by doing a series of bongo net transects along a grid. Bongo nets were towed obliquely and an integrated sample was taken. All nets were rinsed with sea water and the contents preserved immediately in phosphate buffered formalin. Details of the sampling regime, hydrography and station locations are described elsewhere in the report. Samples from the nets were rinsed into buckets and concentrated by sieving through appropriate sized screens then rinsing into labeled containers to which preservative and clean filtered seawater were added. The Pleurobrachia and other gelatinous zooplankton were counted on the sieves before the samples were preserved. A number of Pleurobrachia were measured live from each net in a selected number of MOC-10 tows. The ctenophores were scooped out with a plastic spoon, rinsed in sea water and measured along the oral/aboral axis. Then they were placed back in the samples for preservation.
Thirty bongo samples were examine, both 333µ and 505µ nets representing almost all the stations along the transects. Numbers of Pleurobrachia collected in these samples are shown in Figure 17a. These are raw numbers and have not been converted to numbers per volume towed. Seventeen complete MOC-1 hauls and 4 partial hauls at station 106 were examined and numbers of Pleurobrachia counted; 13 complete and 3 partial at station 100 and 2 complete at station 95. Two graphs showing the distribution of Pleurobrachia by haul and by depth, and distribution by depth in daylight and dark are shown in Figures 17b and 17c as an example of the information collected. These are raw numbers which have not been converted to numbers per volume as the corrected volume filtered was not available when the graphs were made. In general more Pleurobrachia were collected in the daylight samples and at depths of 30-50 meters. Only one station and a few hauls made at that station have been graphed as the data are being converted to volumetric measurements for analysis. Seven complete MOC-10 hauls at Station 106 , two of which were subsampled for live measurements, 5 complete hauls at station 100 one of which was subsampled for live measurements and 1 partial haul at station 95 were examined and numbers of Pleurobrachia. counted. Three sets of live measurements were made from organisms collected in the MOC-10. The average oral to aboral size in mm of the organisms collected were: Net 4, 20.56; Net 3, 20.67; Net 2, 21.76; Net 1, 18.52; Net 0, 21.34. There was no statistically significant differences in ctenophore size in the different nets at the 0.01 level of significance.
We collected replicate day and night discrete depth samples at a shallow and deep station across the tidal front. Predator abundance and distribution was determined from these samples and will be compared to target species abundance and distribution. Live measurements were made on a subsample of Pleurobrachia, and these wil be compared with sizes of preserved specimens from the same tows. Gut contents of Pleurobrachia collected in the MOC 10 will be examined and compared with those collected in the MOC-1 and with divercollected samples from a previous cruise as their is an indication that the guts are fuller in Pleurobrachia that are hand collected. Several copepod feeding experiments were conducted, which will be discussed in another section
Zooplankton Pump Sampling (L. Incze, N. Wolff and F. Dye)
We took 35 pump profiles of zooplankton to provide: (1) detailed prey field information for the larval fish studies of size, feeding, growth rate, distribution and condition (collections using the 1-m MOC); (2) detailed vertical distributions and abundances (including diel changes) to use with transport and mixing calculations (dye studies, hydrographic data and modeling components); and (3) abundance estimates to compare with VPR records from the 1-m MOC and catch rates with the 1/4-m MOC. The VPR attached to the 1-m MOC is a sampling method in development for simultaneous sampling of prey and larval fish (Greg Lough et al.); the 1/4-m MOC has been used on numerous GLOBEC cruises for sampling the prey field, and a comparison of results is needed. The 1/4-m MOC usually samples ~35 m3 from a (vertical) depth stratum of 10 m, whereas the pump sample comes from a small volume at a discrete depth. Pump samples from earlier GLOBEC cruises suggest higher prey field concentrations. We collected a total of 370 samples during this cruise.
Each pump profile was preceded by a standard CTD cast (with fluorometer and Biospherical PAR sensor) for the water column. Pump samples then were taken by attaching one end of a 5 cm x 60 m reinforced hose to the CTD/rosette frame so that the hose opening was near (within ~0.25 m of) the CTD sensors. The CTD was lowered to depth (usually 50 m) and stopped at discrete sampling depths at 5 m intervals up to a depth of 5 m. Time was given for the system to clear at each new depth before sampling. A gas-powered diaphragm pump (same model as used in the 1999 broadscale program and process studies by Durbin, Ohman and others) delivered water from sampling depths to the surface at a nominal rate of 0.3 m3/min. This water passed into a small, rapidly draining reservoir (0.13 m3) on deck to dampen the surge. This reservoir also was drained between sampling depths. A 1.9 cm ID hose carried water from the reservoir to individual samplers equipped with 40 um mesh nets. An electronic timer and flow meter installed in the 1.9 cm hose was started and stopped for each sample, providing very high accuracy measurements of the volumes filtered. The final sampling rate averaged 13 l/min, and most samples were filtered from 27-33 l of water. Samples were preserved in 3-5% buffered formalin. Samples are summarized in Table 4 below.
Table 4. Summary of Zooplankton Pump Profiles
|Station||CTD cast numbers|
|95||9, 12, 14, 15|
|100||46, 48, 51, 52, 53, 54, 55, 56, 83, 84, 85, 86, 87, 88|
|106||28, 31, 33, 35, 37, 39, 41, 44, 67, 68, 69, 70, 71, 72, 73, 74, 89|
Nutrients (D. Townsend)
Nutrient samples were taken for Dave Townsend at 23 CTD stations at near bottom and every 10 meters of the water column .
Appendix I. Event Log
|L OC A L||Water||Cast|
Appendix II. List of Personnel
Dr. R. Gregory Lough, NOAA, Ch. Scientist
Dr. Lew Incze, Bigelow Laboratory
Betsy Broughton NMFS, Woods Hole.
Elaine Caldarone NMFS, Narragansett
Phil Cootey, UMass Boston
Jeanne Burns NMFS, Narragansett
Dr. Grace Klein-MacPhee, URI
Toni Chute NMFS, Woods Hole
Ford Dye, Bigelow Laboratory
Karen Fisher Grad. Student, Cornell University
Marie Kiladis NMFS, Woods Hole
Jim Manning NMFS, Woods Hole
Malinda Sutor NMFS, Woods Hole
Dr. Cisco Werner Univ. North Carolina, Chapel Hill
Nick Wolff, Bigelow Laboratory
Debbie Smith, Maine Maritime Academy
Jenifer Austin, WHOI Internship
Dr. Anne Sell, WHOI
Erich Horgan, WHOI
Sean Ament, San Francisco State University
Master George Gunther
Chief Mate Tony Monocandiles
2nd mate Matt Skelly
Chief Eng. Steve Hyde
Asst. Eng. Bill Reilly
2nd Asst. Eng. Kurt Hayer
Steward Dave Kervin
Seaman Chris Malvern
Seaman Joe Hart
Seaman Dave Foote
Marine Tech. Don Cucchihara
E.T. James Gordon
Steward's Asst. Jamie Sizemore
Appendix III. List of Figures
Figure 1a. Seabird19 CTD cast numbers (top) and station numbers (bottom) on EL9905. Note these are all locations of bongo hauls ( el9905sta.ps, JM).
Figure 1b. Cod (top) and Haddock distribution (bottom) on 11-13 May 1999 from bongo net hauls. (el9905ch.ps, JM).
Figure 2. Drifter deployments during cluster #1 (top) and cluster #2 (bottom). See Table 1 for full description of deployment times and depths (alldrft12.ps, JM).
Figure 3. Drifter deployments during cluster #3 (top) and cluster #4 (bottom). See Table 1 for full description of deployment times and depths (alldrft34.ps, JM).
Figure 4.Shipboard alongtrack record of fluorescence, sst, salinity, and wind. Note the lighter line in the bottommost panel represents the northward component of the wind (mayat130.ps*, KF).
Figure 5. Shipboard alongtrack record of atmospheric pressure, air temperature, and radiation. (mayatmp130.ps*, KF).
Figure 6a. Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide6.ps*, KF).
Figure 6b.Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide12.ps*, KF).
Figure 6c.Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide18.ps*, KF).
Figure 6d Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide24.ps*, KF).
Figure 6e Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide30.ps*, KF).
Figure 6f Shipboard alongtrack record of temperature (bold) and salinity (gray) as a function of tidal flow direction. Estimates of tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area) is indicated by a thin line. The ranges of each variable is denoted on the title line. Each panel represents another tidal cycle ( maytide36.ps*, KF).
Figure 7 Estimates of vertically-averaged tidal velocity (based on Candela's empirical relations derived from previous ADCP records in the area). Spring tide apparently occurred at day 138. The n/s and e/w components are presented in the top and bottom panel, respectively (maytidv130.ps*, KF).
Figure 8a. ADCP observations of current for the week-long period of ADCP operation during EL9905. The three panels represent eastward flow, northwardflow, and volume backscatter, respectively. (a1_con.ps*, JM).
Figure 8b. ADCP record of vertically averaged current (a1_ts_all.ps*, JM).
Figure 8c. Shipboard attempt at Candela detiding. Both the absolute velocity vectors (top) and the estimate of detided velocity vectors (bottom) are presented (a1_vec.ps*, JM).
Figure 9. Cross-bank CTD transect corresponding to cast 22-29 (stations 57-63). Drogues were deployed where indicated (s3.ps, JM).
Figure10a. Surface and bottom temperature distributions for GLOBEC Process cruise EL9905 (el9905t.ps, JM).
Figure10b. Surface and bottom temperature anomalies for GLOBEC Process cruise EL9905.
Figure 10c.Surface and bottom salinity distributions for GLOBEC Process cruise EL9905.
Figure 10d.Surface and bottom salinity anomalies for GLOBEC Process cruise EL9905.
Figure 10e. Cross-bank temperature sections from the SEABIRD/Bongo CTD survey 11-14 May 1999. CAST numbers are listed across the top of each section. See Figure 1. (t19.ps, JM).
Figure 10f. Cross-bank salinity sections from the SEABIRD/Bongo CTD survey 11-14 May 1999. CAST numbers are listed across the top of each section. See Figure 1. (s19.ps, JM)
Figure 10g. Cross-bank sigma-t sections from the SEABIRD/Bongo CTD survey 11-14 May 1999. CAST numbers are listed across the top of each section. See Figure 1. (d19.ps).
Figure 11a. Individual Seabird 911 CTD profiles 1-30. Note the range of temperature and salinity are 2 and 0.4 PSU, respectively (pro130.ps, JM).
Figure 11b. Individual Seabird 911 CTD profiles 31-60. Data is missing for cast 55 and 58. Note the range of temperature and salinity are 2 and 0.4 PSU, respectively (pro3160.ps, JM).
Figure 11c. Individual Seabird 911 CTD profiles 61-89. Note the range of temperature and salinity are 2 and 0.4 PSU, respectively (pro6189.ps, JM).
Figure 11d. Individual Seabird 911 CTD profiles 1-30. Note the range of fluorescence and sigmat is 0.4 volts and 0.5 sigmat units, respectively (profd130.ps, JM).
Figure 11e. Individual Seabird 911 CTD profiles 31-60. Data is missing for cast 55 and 58. Note the range of fluorescence and sigmat is 0.4 volts and 0.1 sigmat units , respectively (pro3160fd.ps, JM).
Figure 11f. Individual Seabird 911 CTD profiles 61-89. Note the range of fluorescence and sigmat is 0.8 volts and 0.5 sigmat units, respectively (pro6189fd.ps, JM).
Figure 11g. Individual Seabird 911 CTD profiles 1-30. Note the range of PAR light and Transmitted light is 4000 and 10 volts units, respectively (pro130lt.ps, JM).
Figure 11h. Individual Seabird 911 CTD profiles 31-60. Data is missing for cast 55 and 58. Note the range of PAR light and Transmitted light is 2000 and 10 volts units, respectively (pro3160lt.ps, JM).
Figure 11i. Individual Seabird 911 CTD profiles 61-89. Note the range of PAR light and Transmitted light is 2000 and 40 volts units, respectively (pro6189lt.ps, JM).
Figure 12a. Cross-bank SEABIRD 911 temperature transects along the mooring line (t911.ps, JM).
Figure 12b. Cross-bank SEABIRD 911 salinity transect along the mooring line (s911.ps, JM).
Figure 12c. Cross-bank SEABIRD 911 sigma-t transect along the mooring line (d911.ps, JM).
Figure 12d. Cross-bank SEABIRD 911 fluorescence transect along the mooring line (f911.ps, JM).
Figure 13a. MOC1 hauls vs tidal phase on EL9905. Note that the maximum eastward flow is nearly concurrent with the maximum on-bank excursion of the tide and the minimum (negative) flow is associated with the off-bank excursion. The observed ADCP record is plotted as a dotted line and the Candela estimate is plotted as a solid line (evmoc1ts.ps, JM).
Figure 13b Distribution of MOC1 cast vs. tidal phase. (evmoc1b.ps, JM).
Figure 14a. Satellite derived SST for 10 May at 1900Z with mooring and drifter positions overlaid. The colormap is chosen to highlight the mid-shelf eddy that occurs between the 60 and 100m isobath (may10_1900.ps, JM).
Figure 14b. Satellite derived SST for 15 May at 1900Z (left panel) with mooring positions (green dots) overlaid. The mid-shelf eddy seen on the previous image (10 May) is still visible. Satellite derived SST for 17 May at 1900Z and 5 June at 0700Z follow in the next two panels. The main features then are eddies forming along the tidal front. The slope water intrusion seen especially on 17 May had fully receded by 5 June.
Figure 15. Flow-chart of shore-based real-time data assimilation system. The larger ADCIRC model grid provided boundary conditions for the smaller QUODDY Bank150 grid (flowA_poster.ps, B.Blanton).
Figure 16. Flow-chart of shipboard real-time data assimilation system (flowQ_poster.ps, B.Blanton).
Figure 17a. Pleurobrachia collected along bongo grid 5/11-5/13 on EL9905 (pleuro1.ps, EH).
Figure 17b. Pleurobrachia distribution by net at station 106 (pleuro2.ps, EH).
Figure17c. Pleurobrachia collected in the MOC-1 at station 106 (pleuro3.ps, EH).