R/V ALBATROSS IV Cruise AL9901 Cruise Report

Acknowledgments

The scientific personnel respectively thank the officers and crew of R/V ALBATROSS IV.

Their cooperation and professional approach to duty helped ensure a successful cruise.

This report was prepared by John Sibunka, Maureen Taylor, Peter Wiebe, Maria Casas, Charles Miller, Rebecca Jones, Stephen Brownell and Keska Kemper with assistance from colleagues in the scientific party. This cruise was sponsored by the National Science Foundation and the National Oceanographic and Atmospheric Administration.

TABLE OF CONTENTS

Purpose of the Cruise 3

Cruise Narrative 5

Individual Reports 11

Hydrography 11

Zooplankton and Ichthyoplankton studies based on Bongo and MOCNESS tows 17

Preliminary Summary of Zooplankton Findings 21

Preliminary Summary of Ichthyoplankton Findings 23

Preliminary Summary of the 10-m2 MOCNESS samples 29

Observations of Zooplankton Collected 31

Nutrients and Phytoplankton Studies 35

Microzooplankton Studies 38

Gelatinous Zooplankton sampling 39

Collections for Genetic Studies 39

High Frequency Acoustics 40

Drifter Deployments 56

Shipboard ADCP (Acoustic Doppler Current Profiler) Measurements 56

Personnel List 57

Scientific 57

R/V ALBATROSS IV Officers and Crew 57

Appendix 1. Data inventory 58

Appendix 2. CTD Plots and Compressed Listings Of the Data 69

Purpose of the Cruise

Six broad-scale surveys are part of the 1999 U.S. GLOBEC Georges Bank Program. These six broad-scale surveys are conducted monthly from January to June to monitor the changing biological and physical status in the Georges Bank ecosystem. The first cruise in this series was aboard R/V ALBATROSS IV (AL 99-01, 12-24 January 1999). The principle objectives of the cruise were to:

(1) Determine the distribution and abundance of the ichthyoplankton and zooplankton community on the Bank and in adjacent Gulf of Maine and slope waters. Emphasis was on target fish (eggs, larval and juvenile cod and haddock) and copepod species (all stages of Calanus finmarchicus and Pseudocalanus sp.) and their predators and prey.

(2) Provide systematic collections of larval and juvenile cod and haddock for age and growth estimates.

(3) Collect individuals of Calanus and the euphausiid, Meganyctiphanes norvegica, for population genetics studies.

(4) Conduct lipid biochemical and morphological studies of Calanus finmarchicus.

(6) Conduct a hydrographic survey of the Bank.

(7) Conduct acoustic mapping of the plankton along the track lines between stations using a high frequency echo sounder deployed in body.

(8) Collect chlorophyll and nutrient data to characterize the potential for primary production and to calibrate the fluorometer on the CTD.

(9) Map the Bank wide velocity field using an Acoustic Doppler Current Profiler (ADCP).

(10) Deploy drifting buoys to make Lagrangian measurements of the currents.

In order to obtain uniform bank-wide coverage, 41 predetermined "standard" stations and 40 "intermediate bongo" stations were scheduled for this survey. During this cruise 41 standard stations were occupied and 38 bongo stations completed. The entire Bank was surveyed, including the portion in Canadian waters (Figure 1).

The 41 standard stations were assigned a priority code number (from 1-4) which reflected the equipment used on a given station. Priority stations assigned code 1 or 2 were "full stations" with "high priority" , and stations assigned code 3 or 4 were "partial stations" and designated "low priority". The intermediate bongo stations were considered to have a lower priority (i.e. priority code number 5) than the 41 standard stations.

Survey operations were a combination of both underway and station activities. The ship's ADCP unit was used to make continuous measurements of the water current profile under the ship, in order to construct the current field over the whole Bank. This data will be used to help in the interpretation of all the other observations made on the cruise. The along track operation consisted of high frequency acoustic measurements of the volume backscatter and nekton throughout the water column and surface measurements of temperature and fluorescence.

Figure 1

Navigation information, meteorological data, and sea surface salinity and temperature were recorded by the vessel's computer system.

At full stations an oblique plankton tow from surface to near bottom was made with a bongo sampler along with a real-time CTD attached to the towing wire. A large volume zooplankton pumping system was use to sample the water column. A Seabird 911 CTD-fluorometer unit was used to characterize the water column. Niskin bottles attached to a rosette were used to collect water samples at selected depths for biological and chemical analysis. Water was also drawn for microzooplankton analysis, salinity determination and H218O/H216O isotope concentration analysis. A 1-m2 MOCNESS (Multiple Opening Closing Net Environmental Sampling System) was towed obliquely from surface to near bottom cycling twice to make vertically stratified collections of zooplankton with both 335 m mesh and 150 m mesh nets, and to make collections of fish larvae with 335 m mesh nets. A 10-m2 MOCNESS fitted with 3.0-mm mesh nets was towed obliquely from surface to near bottom to make vertically stratified collections of larger predators on target species. A 1.5-m2 Jelnet fitted with a 5-mm mesh net was towed vertically to collect fragile gelatinous zooplankton at priority #1 stations. At partial stations, a bongo tow, a Seabird 911 CTD cast, and 1-m2 MOCNESS tow were made. At the intermediate bongo stations, a bongo sampler and real-time CTD were towed obliquely from surface to near bottom. At selected stations, the real-time CTD and a Niskin bottle cast were made for calibration purposes. A summary of sampling events that occurred during this cruise is in Appendix 1.

Cruise Narrative

In this section, reference made to station numbers refers to standard station number. The intermediate bongo tows between stations were generally completed. Bongo tows that were not done were noted in the narrative. Vessel speed did not exceed 7.5 kts while towing the acoustic fish between stations.

11 January

The cruise was initially scheduled to depart at 1400 hrs. Sailing was canceled and rescheduled for 1000 hrs on 12 January. The reasons for the rescheduled sailing time were that the ship had just completed an in-port dockside repair period and some of the contract work for the ship was not completed on time. Also, several items of the scientific equipment needed for the survey were not ready for sea; and the offshore waters where the vessel was to conduct survey operations were experiencing gale force weather conditions. The weather conditions on this day were cloudy with intermittent snow flurries in the morning, then clearing and windy in the afternoon. The air temperature throughout the day was below freezing. The scientific party used the dockside time for setting up, securing and checking out scientific equipment and stowing supplies.

12 January

The scheduled sailing time of 1000 hrs was changed to 1400 hrs based on the weather forecast of continued gale force northeast winds of 30-40 kts in the morning. These winds were predicted to diminish during the afternoon hours. Departure was delayed again and rescheduled from 1400 to 1600 hrs. The reason for the rescheduled 1400 hr departure time was that a flowmeter system for the scientific pumping operation was not on board the ship. This flowmeter had to be delivered from Rhode Island. During this waiting period, meetings for both vessel indoctrination and scientific protocol and survey operations were conducted for the scientific party. The R/V ALBATROSS IV departed NEFSC Woods Hole, Massachusetts, at 1633 hrs. Running time to the first station was estimated to be about eight hours. Weather conditions during the afternoon had improved with east winds of about 10 kts, and a subsiding sea state. The air temperatures during the day had risen to above freezing.

13 January

Stations completed were 1, 2(no Seabird-CTD cast), 41, and 3(no 10-m2 MOCNESS tow or Jelnet cast). Survey operations began at 0035 hrs on station 1. The inclinometer on the 1-m2 MOCNESS needed to be reset prior to deployment. The acoustic fish (Greene Bomber) was deployed at this station. On station 2, the Seabird-CTD (SB911) stopped working during the cast. The cause of this problem could not be quickly resolved and a vertical cast with the Seabird profiler was substituted. A 1.7 liter Niskin bottle was attached to the wire above the Seabird Profiler to obtain a water sample at maximum wire out during the cast. This protocol was followed on subsequent stations until the SB911 was repaired and used. Later in the cruise this protocol was also used if adverse weather conditions were such that the SB911 could not be safely deployed. The ship conducted a fire and a abandon ship drill while en route to the intermediate bongo between station 41 and 3. On the intermediate bongo station between stations 41 and 3, the SB Profiler would not at first communicate with the computer used in operating the Profiler program. The problem was finally traced to a locked comport on the computer and rectified by re-booting the computer. On station 3, the SB911 was carried from its storage area on the starboard side of the ship and deployed off the port side using the main boom and its conductor wire. At the completion of the cast it was returned to its storage area. This procedure was cumbersome as several personal on watch were required to move the SB911 across the deck and over the towing wires used for the acoustic fish and for the 10-m2 MOCNESS sampler. Weather conditions during the morning were pleasant with light winds, partly sunny skies and air temperatures ranging from 10 to 11C. Due to deteriorating weather conditions with an increase in wind and sea state, no Jelnet cast or 10-m2 MOCNESS tow was made at this station. During the evening hours, the winds had shifted to the northeast and increased to 25-30 kts with an accompanying rise in sea state.

14 January

Stations completed were 4(no intermediate bongo tow made between station 3 and 4; no pump profile or 10-m2 MOCNESS tow), 5, and 6. The ship proceeded at a reduced speed to station 4 because of gale force weather conditions. The winds at this time were northeast at 25-35 kts and the air temperature was around the freezing point. Due to adverse weather conditions on station 4, survey operations were limited. No pump cast or 10-m2 MOCNESS tow were made. A cod end collection bucket was lost during the 1-m2 MOCNESS tow from net #3. Station 5 was completed without incident. Weather conditions had moderated slightly by station 6. A case of formalin preserved 1-m2 MOCNESS samples accidentally fell to the deck of the main laboratory with the loss of four jars. The clean up of these broken samples was done quickly by both the scientific personnel and members of the deck crew on the night watch at the time of the mishap. By the evening when the ship commenced station operations on station 7, the weather conditions had improved. The winds from the northeast had subsided to 20-30 kts, and this was accompanied with a decrease in sea state. During the sampling tows on station 7, for the bongo, 1-m2 MOCNESS and 10-m2 MOCNESS, each of the respective samplers fouled longline fishing gear. This longline gear had to be cleared prior to retrieval of these samplers back on board the ship. No damage occurred to any of the samplers as a result of the entanglement of the fixed fishing gear. At the completion of the pumping operation the intake portion of the pump hose broke free of the winch wire. The failure of the pump intake hose is attributed to both material fatigue and stress due to current sea state. While personnel on deck began retrieving the sections of pump hose that had been deployed for the cast, the hose separated from its end fitting joining the adjacent section of hose already back on board the ship. As a result of this hose/fitting separation, 90 meters of hose were lost. This loss would now limit pump operations on subsequent stations to a maximum sampling depth of 50 meters. By late evening, the wind had shifted to the east and decreased to about 20 kts.

15 January

Stations completed were 7(no Jelnet cast), 8, 9(no pump or Jelnet cast, no 10-m2 MOCNESS tow) and 10. The weather forecast for the morning hours was for the wind to veer to the southeast at 20-25 kts. The air temperature during the morning hours had risen to about 7C. Sea state was still high and now confused as a result of shifting winds. Scientific personnel with the assistance of the deck crew repaired the damaged pump hose and constructed a new sea water intake assembly for the end of the pump hose to replace to the one lost at station 7. Station 8 completed without incident. Because of the large ground swell that was present while the ship was conducting survey operations on station 9, no pump cast or Jelnet cast were made. The 10-m2 MOCNESS was deployed, but the tow was aborted early in the cast due to excessive surging of the towing wire as the ship pitched heavily into the large ground swells. At the completion of the 1-m2 MOCNESS tow at station 10, number 4 net was found to be damaged and replaced. The net mesh had separated from the fabric collar on the top section of the net. Weather conditions during the afternoon and evening hours were cloudy skies with periods of rain followed by light fog. Air temperatures ranged from 10 to 12C. The winds had shifted to the south at about 20 kts, then to the west-southwest by midnight, with an increase in velocity to 30 kts. Sea conditions changed from a heavy southerly ground swell in the afternoon and early evening to a confused sea state by late evening.

16 January

Stations completed were 11, 12(no pump or Jelnet cast, no 1-m2 MOCNESS or 10-m2 MOCNESS tow; a second bongo tow was made) and 13(no 10-m2 MOCNESS tow). A strong weather system with westerly gale force winds of 25-30 kts, with wind gusts to 40 kts limited station operations in the early morning hours. A drifter buoy was deployed at the end of station 11. On the arrival of the ship at station 13 the weather conditions had deteriorated such that the Greene Bomber was brought on deck. The ship was secured for adverse weather conditions and began jogging until weather conditions improved to commence survey operation again. By 1700 hrs the weather conditions had improved to resume survey operations on station 13. The west wind had diminished to 20-25 kts with an accompanying decrease in sea state. The night sky was clear and the air temperature during the evening hours ranged from 5.5 to 8.3C.

17 January

Stations completed were 14, 15, 16 and 17. Survey operations went smoothly this day. The problem with the SB911 CTD was traced to a faulty electric wire splice on a pig tail connection. The splice was redone and the CTD unit was deployed on station 16. The recoil spring on the manual pull starter cord of the centrifugal pump motor broke while trying to start the motor on this station. As a result the starter cord had to be rewound manually by rotating the fly wheel assembly on the motor in a counter-rotational direction. This procedure for rewinding the starter pull cord had to be done every time this motor was used for the remainder of the cruise. Weather conditions improved greatly as the day progressed. The west wind by late evening had diminished to light and variable with an accompanying calm sea state. The air temperature during the day had reached a high of 10C, and had decreased to about 4C by the change of the watch at midnight.

18 January

Stations completed were 18, 19, 20, 21, 22, and 23. On station 19 the Greene Bomber stopped recording and was retrieved on board the ship for repair. Until the repairs to the acoustic fish were completed the ship ran at full speed between stations. En route to station 20 the ship crossed the Exclusive Economic Zone boundary line between the United States and Canada and entered Canadian waters. Repairs to the Greene Bomber were completed and the acoustic fish was again deployed on station 22. Weather conditions during the day were spring like with winds light and variable during the early hours of the day and becoming southeast less than 15 kts through mid-afternoon. The air temperature during this time was about 6.5C. By late evening the southeast winds had increased to 25-30 kts. The weather forecast predicted that a strong weather front was to pass across the survey area during the night and the frontal passage would be accompanied with gale winds and possible thunder storms.

19 January

Stations completed were 24(no SB911 cast, no intermediate bongo tow made between station 24 and 25), 25, 39 and 26. While on station 24, at approximate 0230 hrs, a severe weather front accompanied with thunder, lightning and heavy rain squalls passed the area of operation. The southeastly winds abruptly veered to the south and increased rapidly to 40+ kts. The air temperature dropped from 11.5 to 9.5C. This occurred during the completion of the first tow cycle of the 1-m2 MOCNESS tow. The sudden force of this squall system pushed the ship over the towing wire of the 1-m2 MOCNESS system. The ship was quickly cleared of the towing wire and brought back under control. Because of the existing weather conditions it was decided to abort the second cast cycle of the 1-m2 MOCNESS tow and bring the system back aboard the ship. While crew members of the deck department and scientists on watch were waiting for the 1-m2 MOCNESS to clear the sea surface, a very large sea hit the ship and this wave broke across the trawl deck flooding the entire stern area of the vessel. No injuries occurred and the 1-m2 MOCNESS was finally retrieved and secured on board the ship. The chief scientist was summoned. The Greene Bomber was also brought on board the ship and secured on deck. Survey operations were suspended and the ship slowly jogged toward station 25. No intermediate bongo tow was made between station 24 and 25. While en route to station 25, the winds moderated and the seas subsided enough so as to allow deployment of the Greene Bomber. By the time the ship arrived at station 25, the wind had shifted to the northwest and decreased to about 15 kts. However, the sea state while working this station was confused. By mid-day the sky had cleared and sunny conditions finally prevailed. The air temperature ranged from 6 to 7C. Survey operations for the rest of the day were routine and without incident.

20 January

Stations completed were 27, 28(no SB911 cast) and 29. The weather conditions during the morning hours were clear to partly cloudy skies with northwest winds of 20-30 kts. Air temperature during this time stayed steady at 6.3C. Two drifter buoys were deployed at the end of station 27. On station 28 the SB911 CTD was not deployed because of sea state. A vertical cast with the Seabird Profiler and Niskin bottle was made instead. At station 29, the SB911 was deployed off the main boom. The ship conducted a fire and a abandon ship drill between survey operations on station 29. At the completion of the intermediate bongo after station 29, the ship retrieved the Greene Bomber and broke off survey operations. The reason for this break in the cruise was to rendezvous with a U. S. Coast Guard cutter off Chatham, Massachusetts, to debark two crew members. The ship began its estimated twelve hour run at full speed at 2005 hrs. The weather conditions during the evening hours were partly cloudy skies, with a northwest wind of 15-20 kts. Air temperatures ranged from 4 to 5C.

21 January

Stations completed were 32 and 30. The weather during the morning hours and throughout the day were spring like with mild air temperatures, sunny skies, light north winds and calm sea conditions. The rendezvous with a U. S. Coast Guard launch off Chatham was made at 0818-0825 hrs with the transfer of personnel and scientific supplies. Three thirty-meter sections of submersible pump hose were taken aboard the R/V ALBATROSS IV from the CG launch. Arrangements with the Coast Guard had been made by the port office at the NEFSC, Woods Hole, Massachusetts, and the NEFSC Laboratory at Narragansett, Rhode Island for the transportation and transfer of the needed pump hose. Upon completion of the transfer, the ship proceeded full speed to resume survey operations at station 32. It was decided to begin survey operations at station 32 and then proceed to station 30 in an effort to make up for lost survey time. The ship was on station 32 at 1745 hrs. Weather conditions during the evening and night hours were still mild with calm winds and seas.

22 January

Stations completed were 40, 31(no SB911 cast) and 33. Spring like weather conditions still prevailed during the morning hours with calm winds and seas. The air temperatures during this time ranged from 5 to 6C. At station 31 the SB911 CTD did not respond to the "power up" command. Vertical casts with the Seabird profiler and Niskin bottles were made(refer to the "Hydrography" section in this report for details on profiler cast protocol). The problem was traced to a blown fuse which was replaced. A series of replicate pump casts were made at this station(refer to the "Zooplankton and Ichthyoplankton studies based on bongo and MOCNESS tows" section of this report). During the late afternoon and evening hours the weather conditions began to deteriorate as northeast winds increased to 20-30 kts and the seas began to build.

23 January

Stations completed were 34(no SB911 cast or 10-m2 MOCNESS tow), 35, 36 and 37. The weather conditions during the late night and early morning hours were easterly winds at 20-25 kts gradually shifting to the southeast at the same speed. By mid morning the southeast winds began to diminish to 15 kts and less, with a accompanying decrease in sea state. The air temperature at this time was mild, centering around 7C. The weather forecast predicted strong southerly gales of 40-45 kts with higher gusts for late in the evening and continuing onto tomorrow, Sunday, 24 January.

A series of replicate pump casts were completed at station 34. The centrifugal pump motor was difficult to start as a result of dampness effecting the electrical system and the engine being worn and "tired". However, through efforts of both the scientific party and deck department the motor was started for each of the pump comparison casts. Because of adverse weather conditions at station 34, the 10-m2 MOCNESS was not deployed. Survey operations were routine for stations 35 to 37. During the initial tow at station 36, the seabird profiler stopped recording early in the cast and the tow was aborted. Prior to arriving on station, the batteries for the profiler were changed. The various possibilities for the cause of the problem were perused including the new batteries. The cause for the failure was the result of a new battery manufactured with reverse polarity. The defective battery was replaced and a subsequent bongo tow was completed on station. The ship arrived on station 38 at 1730 hrs, the last station for the survey. In an attempt to accommodate a request for live zooplankton organisms(refer to the "Zooplankton and Ichthyoplankton studies based on bongo and MOCNESS tows" section of this report), a "live tow" was to be made at this station. Gear deployment on this station was changed from the normal protocol in that the 1-m2 MOCNESS was towed first so as to examine the resultant samples for the presence of requested organisms. A retow was then to be made after the completion of the pumping operation on this station. The pumping operation entailed the last of the series of replicate pump casts. The Greene Bomber was recovered and secured on deck. The weather conditions during the evening hours were southerly winds of about 15 kts, subsiding seas, and fog. The air temperature increased to 10.3C by midnight.

24 January

Completed station 38. At 0032 hrs, with the deployment of the second of the two drifters released at this station, the ship began its estimated 8-9 hour run to port at full speed. The scientific party began dismantling and packing scientific gear and equipment. The southerly winds began to increase in velocity in the late night and early morning hours. By sunrise the predicted gale force winds of 40 and higher knots had arrived in the survey area to accompany the ship to port. The R/V ALBATROSS IV arrived at the NEFSC Woods Hole, Massachusetts, dock at 0809 hrs and completed cruise AL9901. The docking operation was done quickly and smoothly by the bridge officers in spite of the high winds of 40-50 kts.

Individual Reports

Hydrography

(Maureen Taylor and Cristina Bascuñán)

The primary hydrographic data presented here were collected with Seabird CTD systems. The Seabird 911+ CTD (SBE911+) provides measurements of pressure, temperature, conductivity, and fluorescence and records at a rate of 24 observations per second. This CTD is equipped with a rosette (Seabird 32 carousel) for collecting water samples at selected depths. Bongo hauls were made at each of the stations occupied. A Seabird model 19 profiling CTD (SBE19 Profiler) was used on each bongo tow to provide depth information during the tow. Pressure, temperature, and salinity observations are recorded twice per second by the Profiler.

The following is a list of the CTD data collected with each of the sampling systems used on the cruise:

Instrument # casts

SBE911+ 23

SBE911+ calibration 23

SBE19/ Bongo 80

SBE19/ calibration 18

The SBE911+ was deployed with 9 bottles on the rosette and samples were collected for various investigators. At priority 1 and 2 stations, 400 mls were immediately siphoned out of two Niskin (bottom and mid-depth) for observations of micro-zooplankton swimming behavior (S. Gallagher, WHOI). Samples were collected for oxygen isotope analysis at selected depths (R. Houghton, LEDO) and a sample was taken at the bottom for calibrating the instrument's conductivity data (D. Mountain, NMFS). Samples for chlorophyll and nutrient analysis were taken from multiple depths at each of the standard stations (D. Townsend, Univ. of Maine).

Parameter # samples

oxygen isotope 127

Species composition 17

Data:

Preliminary processing of the SBE Profiler and 911 data was completed at sea using the Seabird manufactured software routines to produce 1 decibar averaged ASCII files. This was the first cruise using the SBE911+ CTD system with the Seabird carousel. At station 2, a broken conductor in the pigtail of the sea cable caused the fuse to blow in the CTD deck box. We were unable to find a replacement .5 amp fuse (until a few days later) but were able to successfully collect data (off the boom winch) with a .25 amp fuse. Unfortunately, weather prevented the CTD from being deployed safely until stn station 15. Niskin bottles were hung in line with the Profiler at stations where conditions were too rough for the larger CTD package to be deployed. These operations are referred to as "ASBCAL" in the event log. After the termination on the hydro winch was repaired and weather improved, operations resumed from this winch without any problems. Dive weights (50+ lbs) were strapped to the CTD to dampen the swinging motion during deployment and recovery.

The CTD package is a bit tall for use from the hydro winch. It is difficult for the crew members to release and attach the support shackle because there is only approximately a 2" clearance from the roller track that holds the CTD. Modifications to either the CTD track or to the CTD frame are recommended by the bosun before the next GLOBEC cruise in May. The easiest solution is to deploy off the boom during the May and June cruises.

Results:

The surface and bottom temperature and salinity distributions are shown in Figure 2. Temperature and salinity anomalies (using the MARMAP reference) are shown in Figure 3. The distribution of fluorescence (expressed in volts) are shown in Figure 4 (left). Fluorescence data were only collected at stations where the SBE911+ was deployed. The Seacat Profilers are not equipped with a fluorometer. Stratification in the upper 30 meters of the water column and the stratification anomalies were calculated using the MARMAP hydrographic data as the reference. These distributions, expressed in sigma-t units, are shown in Figure 4 (right).

The volume average temperature and salinity of the upper 30 meters were calculated for the four sub-regions shown in Figure 5. These values are compared with characteristic values that have been calculated from the MARMAP data set for the same areas and calendar days. The volume of Georges Bank water (salinity < 34 psu) was also calculated and compared against the expected values. A CTD profile (from either the Seacat Profiler or SBE911+ system) are provided for each standard station with a compressed listing of the preliminary data in Appendix 2. Note that the cast numbers are not necessarily in sequential order in Appendix 2 because of the use of the different CTD systems.

All four regions of the Bank exhibited relatively fresher conditions. Three stations in the center portion of the Bank (stn stations 4, 10 and 11) showed salinities < 32 psu. The western regions were warmer while the eastern regions were slightly colder than the expected properties. Deep stations on the southwestern flank of the Bank may show the influence of a Gulf Stream meander although imagery during the cruise period was mostly cloud covered (see Figure 2).

Little stratification was observed except along the southern flank and the Northeast Peak where the presence of Scotian shelf water creates a low density layer.

Figure 2

Figure 3

Figure 4

Figure 5

Zooplankton and Ichthyoplankton studies based on Bongo and MOCNESS tows.

(John Sibunka, Maria Casas, James Pierson, Stephen Brownell, Rebecca Jones, Neile Mottola and Joshua Fredrickson)

Objectives:

(1) Principle objectives of the ichthyoplankton group in the broad-scale part of the U.S. GLOBEC Georges Bank Program were to study the composition of the larval fish community on Georges Bank, to define larval fish distribution across the Bank and within the water column, to determine those factors which influence their vertical distribution, and to determine bank-wide versus "Patch-Study" mortality and growth rates. Emphasis in this study is on cod and haddock larvae along with their predators and prey. This study also includes larval distribution and abundance, and age and growth determination. These objectives were implemented through use of bongo net and 1-m2 MOCNESS to make the zooplankton and ichthyoplankton collections. A 10-m2 MOCNESS was used to collect larger pelagic invertebrates and juvenile fish.

(2) The primary objective of the zooplankton group was to complete a bank-wide survey of Georges Bank to determine the distribution, abundance, and stage composition of the target species Calanus finmarchicus and Pseudocalanus spp. A second objective was to identify, quantify, and describe the occurrence of abundant non-target species in order to provide a description of the environment occupied by the target species. These objectives were implemented by using the 1-m2 MOCNESS for sampling copepods and larger zooplankton. A 1.5-m2 Jelnet cast was made to collect gelatinous predators and a submersible pump was deployed for sampling the small copepod naupliar stages.

In addition to these objectives, the zooplankton group was responsible for obtaining

subsamples from the 1-m2 MOCNESS hauls for population genetic studies of Pseudocalanus spp. to be completed by Dr. A. Bucklin at the University of New Hampshire.

Methods:

Bongo tows were made with a 0.61-m frame fitted with paired 335 m mesh nets. A 45 kg ball was attached beneath the bongo frame to depress the sampler. Digital flow meters were suspended in the mouth of each net to determine the volume of water filtered. Tows were made according to standard MARMAP procedures, (i.e., oblique from surface to within five meters of bottom or to a maximum depth of 200 m while maintaining a constant wire angle throughout the tow). Wire payout and retrieval rates were 50 m/min and 20 m/min respectively. These rates were reduced in shallow water (<60 m) to obtain a minimum of a five minute tow or reduced due to adverse weather and sea conditions. A Seabird profiler CTD was attached to the towing wire above the frame to monitor sampling depth in real time mode and to measure and record temperature and salinity. Once back on board, the 335 m mesh nets were rinsed with seawater into a 330 m mesh sieve. The contents of one sieve were preserved in 5% formalin and kept for ichthyoplankton species composition, abundance and distribution. The other sample was preserved in 95% ethanol and kept for age and growth analysis of larval fish. The same preservation procedure was followed as for the 1-m2 MOCNESS.

At stations where the 1-m2 MOCNESS system could not be used due to adverse weather conditions, a second bongo tow was made. This frame was fitted with both 335 m mesh and 200 m mesh nets. Digital flow meters were suspended in the mouth of each net to determine the volume of water filtered. Tows were made according to standard MARMAP procedures except maximum tow depth was 500 m. Wire payout and retrieval rates were 50 m/min and 20 m/min respectively. The nets were each rinsed with seawater into a corresponding mesh sieve. The 200 m mesh sample was retained for zooplankton species composition, abundance and distribution, and preserved in 10% formalin. The other sample (335 m mesh) was kept for molecular population genetic analysis of the copepod, Calanus finmarchicus, and preserved in 95% ethanol. After 24 h of initial preservation, the alcohol was changed.

The 1-m2 MOCNESS sampler was loaded with ten nets. Nets 1-4 were fitted with 150 m mesh for the collection of older and larger copepodite and adult stages of the zooplankton. Nets 0, and 5-9 were fitted with 335 m mesh for zooplankton (nets 0 and 5) and ichthyoplankton (nets 6-9) collection. Tows were double oblique from the surface to within 5 m from the bottom. The maximum tow depth for nets 0, 1 and 5 was 484 m, and for net 6 was 200 m (if net 5 was sampled deeper than 200 m, it was returned up to 200 m and closed). Winch rates for nets 0-5 were 15 m/min and for nets 6-9, 10 m/min. The depth strata sampled were 0-15 m, 15-40 m, 40-100 m, and >100 m. The first (#0) and sixth (#5) nets were integrated hauls. For shallow stations, with only 2 or 3 of the depth strata, not all nets were fished. The contents of nets 0-4 were sieved through 150 m mesh sieve, subsampled using a 2-L plankton sample splitter if the final biomass volume was too large for one quart jar, and then preserved in 10% formalin. Samples from nets 5-9 were sieved through 330 m mesh sieve and preserved in 95% ethanol. After 24 h of initial preservation, the alcohol was changed. The used ethanol was retained for disposal or recycling ashore. At priority 1 and 2 stations and at station 40, 100-ml subsamples from the bottom and surface 150 m mesh nets were removed and preserved in 10% formalin for Dr. C. Miller (OSU). At priority 1 and 2 stations, 100-ml subsamples from nets 2, 3, and 4 were removed and preserved in 95% ethanol. These samples were collected for Dr. A. Bucklin for population genetic studies to distinguish the Pseudocalanus species found on Georges Bank.

The 10-m2 MOCNESS was loaded with five 3.0 mm mesh nets. Tows were oblique from surface to ~10 m from bottom or a maximum depth of 500 m. The same depth strata were sampled as with the 1-m2 MOCNESS. The winch rate for retrieval varied between 5 and 20 m/min depending on the depth stratum. The slow winch rates were used in order to filter at least 4,000-5,000 m3 of water per depth stratum sampled. A stepped oblique tow profile during retrieval was used to achieve this, if needed. Catches were sieved through a 330 m mesh, and preserved in 10% formalin.

Zooplankton Pump Sampling: In order to collect nauplii and younger, smaller copepodite stages of zooplankton, a gasoline powered diaphragm pump was used at all priority 1 and 2 standard stations. A centrifugal Pacer pump was used at all priority 1 standard stations in addition to the gasoline powered diaphragm pump. At stations 31, 34 and 38 a comparison pump was made between the diaphragm pump and the centrifugal Pacer pump which had been in use in previous Broad-scale cruises. Analysis of the pump samples from previous years suggested the possibility that the youngest developmental stages of Calanus finmarchicus (the first nauplius stage, N1, and possibly the second, N2), were being lost during the process of sampling with the centrifugal pump. In an earlier test with a diaphragm pump during February of 1998, we collected more N1s than with the centrifugal pump, and the series of comparisons between the two pumps carried out during this cruise should provide us with more conclusive evidence.

The same general procedure for deploying the pump hose was followed at both standard and comparison pump stations. The intake hose was used for both pumps and was deployed off the main boom by connecting the intake end, fitted with a 1.7-L Niskin bottle cut in half lengthwise, to the winch wire. The boom winch meter block was zeroed at the surface and the wire out reading was used to determine the depth of the cast. Two 45 kg weights were used to depress the array. Two, three or four 30-m sections of 7 cm diameter hose were connected to the pump (depending on the depth of the station), allowing the intake hose to attain a maximum depth of approximately 100 m. At shallow stations, the intake hose nozzle was lowered to 3 meters off the bottom. With the centrifugal pump water went directly to the flow meter and then into the 35 m mesh collection net, while with the diaphragm pump the output was diverted to a surge dampener and then to the collection net. This caused the flow to be more laminar as it passed the flow meter and into the net, allowing a more accurate measurement of flow rate. Once the hose had been deployed to the desired depth it was raised at a constant rate and samples collected. Wire retrieval rate was approximately 4 m/min which provided volumes of about 200 L per 5 m depth interval with the diaphragm pump. After raising of the hose had begun, an interval was allowed for the hose to flush before collection began. Similarly, once the hose had reached the surface the hose was allowed to flush before collection was completed. Flushing time was a calculated time depending on the length of hose used at a station and on which of the two pump systems were used. At regular pump stations with a maximum sampling depth of more than 85 m, samples were taken from the maximum depth to 75 m, 75-40 m, 40-15 m, and from 15 m to surface. At stations with a maximum sampling depth of less than 85 m, samples were taken from the maximum depth to 40 m, 40-15 m, and 15 m to surface. The depth at which nets were switched at the top of each depth interval was adjusted depending on the wire retrieval rate and the hose flushing time to allow water to be flushed through the hose.

For the comparison pump a series of three profiles of the entire water column were collected with each pump. Each pump was alternately deployed, collecting a single sample from the bottom (to 100 m maximum depth) to the surface. The samples were collected only while the hose was being raised as in the standard protocol.

All samples were sieved through a 30 m mesh sieve and preserved in 10% formalin.

Modified Pump Protocol: Due to a mishap at standard station 7, the above described protocol was modified. The 1.7-L Niskin bottle hose intake attached to the winch wire broke as the hose was being retrieved after the pump cast. The extra added stress of the hose full of water resulted in one of the fittings pulling out from the hose on deck sending three sections to the bottom. A modified intake system was assembled by the R/V Albatross IV crew and scientists. This was attached to the remaining 30 m section of hose left on deck and several other pieces which were joined together for a total hose length of 47 m. After station 7, the maximum sampling depth was about 40 m. Due to personal emergencies of two crew members, the ship had to steam to Chatham, Massachusetts, to offload the crew members; at which point three 30 m lengths of new hose were transferred on board. As a result, from standard station 30 onwards, we were able to sample to a maximum depth of 100 m again.

Collection of live zooplankton: To collect live specimens of zooplankton, an additional 1-m2 MOCNESS cast was made at standard station 38 using the #0 and #1 nets only (335m and 150m mesh size). Vessel speed was 1.5 kts; wire payout was ~40m/min and the retrieval rate was <5 m/min.

The zooplankton collected in the cod end buckets were allowed to settle for several minutes. The top portion of the zooplankton, mostly Centropages typicus and Metridia lucens were gently released into 30-gallon plastic cans previously filled with seawater using the diaphragm pump system. These animals were to be used by Dr. William Macy III at the University of Rhode Island for ongoing herring feeding experiments. The settled part of the collection, mostly the pteropod Limacina retroversa were also released into similar 30-gallon containers and returned to Woods Hole to be used by Dr. Scott Gallager for both rearing and behavior experiments.

Samples Collected by the Zooplankton and Ichthyoplankton Groups:

Gear Tows Number of Samples

1. Bongo nets, 0.61-m 80 tows 79 preserved, 5% formalin

335-m mesh 80 preserved, EtOH

200-m mesh 1 preserved,10% formalin

2. MOCNESS, 1-m2 40 tows

150-m mesh(Nets 1-4) 118 preserved, 10% formalin

335-m mesh(Net 0) 38 preserved, 10% formalin

335-m mesh(Nets 5-9) 155 preserved, EtOH

3. MOCNESS, 10-m2 15 tows

3.0-mm mesh 122 preserved, 10% formalin

4. Pump

35-m mesh (centrifugal) 17 profiles 31 preserved, 10% formalin

35-m mesh (diaphragm) 25 profiles 51 preserved, 10% formalin

5. Jelnet 6 tows

1.5-mm mesh 3 preserved, 10% formalin

Preliminary Summary of Zooplankton Findings.

(Maria Casas, James Pierson, Neile Mottola and Joshua Fredrickson)

Preliminary observations were made from the samples collected using the 1-m2 MOCNESS after preservation. As in last year's January cruise, AL 98-01, the dominant copepod of all the Georges Bank region was Centropages typicus. Numbers were abundant at almost all stations sampled. Similarly, numbers of Cajanus finmarchicus were low throughout most of the Bank. Where they were present in moderate numbers along the northeast peak and the deeper slope stations north of the Bank, their developmental stage was mostly C5, implying that their life cycle was somewhat delayed for the time of year.

The shelled pteropod, Limacina retroversa, was again abundant throughout the sampling grid. The diatom, Coscinodiscus, was also present at most of the stations, but their numbers hadn't reached "bloom" proportions yet.

Brief descriptions of zooplankton species composition appear below. Observations were made at most standard stations sampled during this cruise from the net #0 samples (335 m mesh) 1-m2 MOCNESS, unless otherwise stated.

Station 1 and 2 Centropages typicus made us the majority of the copepod component of the zooplankton. Cajanus finmarchicus was absent but there were a small number of Pseudocalanus spp. and Metridia lucens. Chaetognaths, hyperid amphipods, bryozoans, pteropods, and a few hydroids made up the balance of the zooplankton.

Station 41 and 3 Some C. finmarchicus were present at these stations, mostly stage C5. But again C. typicus and Oithona spp. were extrelely abundant as was M. lucens. Pteropods and chaetognaths were abundant.

Station 4 C. typicus most abundant with some Temora longicornis also in the sample. No C. finmarchicus here. Chaetognaths and ctenophores made up the balance of the plankton.

Station 6 Pseudocalanus were present in moderate numbers, in addition to many C. typicus, young M. lucens and Oithona spp. Gastropods extremely abundant.

Station 7 This deep station was made up mostly of M. lucens, C. typicus and such off bank species as Euchaeta norvegica and Pleuromamma spp. Euphausiids were also present in large numbers.

Station 8 C. typicus was again abundant at this station with much lesser numbers of M. lucens, Pseudocalanus spp., and C. finmarchicus. Larvaceans, pteropods and chaetognaths were other zooplankton.

Station 9, 10, 11, 12, and 13 The copepod component at these stations were made up of C.typicus, M. lucens, and T. longicornis. Cajanus appeared to be absent. The balance of the plankton was made up of chaetognaths, hydroids, and mysids.

Station 17 and 19 The copepod component was similar to the previous stations. In addition, gammerid amphipods, bryozoans, Limacina, medusae, chaetognaths, and the diatom Coscinodiscus were abundant.

Station 22 Few C. finmarchicus were present at this station. C. typicus, Oithona spp. and M. lucens were the most abundant copepods. The diatom, Rhizosolenia, was present in large numbers, as were pteropods, gastropods, bivalve larvae, and ctenophores.

Station 23 and 24 A mix of M. lucens, C. typicus and some C. finmarchicus were the copepod component of the plankton. The balance was made up of Rhizosolenia, larvaceans, pteropods and bryozoans.

Station 25 and 39 C. finmarchicus were present here in greater numbers, mostly C5 and older stages. M. lucens, Pseudocalanus spp., C. typicus, and Oithona spp. were also present. Rhizosolenia, Coscinodiscus and Ceratium very abundant.

Station 27 M. lucens, C. finmarchicus, C. typicus and T. longicornis were at this station. Other plankton present were gammerid amphipods, chaetognaths, hydroids and Coscinodiscus.

Station 29 At this off bank station there was a mix of C. typicus, M. lucens and C. finmarchicus (mostly C5, some adult females and males). Candacia armata was also present in moderate numbers. Pteropods, chaetognaths and siphonophores made up the balance of the plankton.

Station 30 Huge numbers of C. typicus were present at this station with some T. longicornis mixed in. No Cajanus.

Station 40 Similar zooplankton component as at station 29.

Station 35 A mix of C. hamatus, C. typicus and Pseudocalanus spp. No Cajanus.

Station 36 The copepod component was mostly made up of C. hamatus. There were also some numbers of C. typicus, and Pseudocalanus. No Cajanus.

Station 38 C. finmarchicus was present at this station in the deeper layers. Closer to the surface were M. lucens and C. typicus.

Preliminary Summary of Ichthyoplankton Findings.

(Rebecca Jones and John Sibunka)

All samples from the Bongo net B were subjected to a preliminary examination for eggs and larvae while on ship. The samples were preserved in 5% formalin, and observed while in the jar with the aid of a magnifying glass. The following qualitative observations of the larval size, abundance and egg abundance were made in the jars after preservation. The formalin-preserved samples are clearer, and delicate eggs are less likely to collapse as those preserved in ethanol.

See cruise reports EN276 (January 1996), AL9701 (January 1997), and AL9801 (January 1998) for the following references to ichthyoplankton findings during 1996-1998.

Sand lance (Ammodytes sp.)

There were two species that were abundant: sand lance and Atlantic herring respectively. Sand lance were ubiquitous with the exception that none were collected along the southern edge of the Bank. Concentrations were highest on the central portion with number of specimens estimated between 50-60 larva/station. Their sizes ranged from 7mm to 35mm with the largest fish occurring in the northwestern region and smallest fish on the southeastern third of the Bank (see Figure 6). In the past three years of sampling on Georges Bank in January (no January cruise in 1995), there was a greater abundance of larvae on the Bank. However, these larvae were more localized in that they were concentrated in the central portion of the Bank. It is possibly that this years sand lance spawning event had already been underway for several weeks, and that the hatched larvae were advected away from their spawning region(s).

Atlantic herring (Clupea harengus)

The greatest larval herring concentrations found during this survey occurred on the mid to eastern third portion of the Bank. The samples examined from stations 13(~60 larvae), 54(~50 larvae) and 32(~40 larvae) had the largest number of specimens collected during this January cruise. Most fish collected were within the size range between 15-45mm length. The smallest herring larvae collected (size range 5-20mm length) were collected at stations 43 and 41. The largest larva (size ~70mm length) was captured at station 59( Figure 7). Most of the larvae collected on this cruise were smaller than 25mm length, which was the minimum size of larvae collected in 1998. Herring larvae collected in January of 1997 ranged in size from 17-50mm length. The smaller sizes of herring larvae collected on this survey may be the result of either a late start in the 1998/1998 spawning season or a more protracted spawning event occurred this year. Results from the January survey in 1998 indicate that herring larvae were primarily located on the western portion of the survey area. Herring larvae collected in January of 1997 were mainly concentrated on the central part of the Georges Bank. When compared to the catch results from the 1997 and 1998 January surveys, herring larvae collected during this survey were more wide spread over the Bank.

Figure 6

Figure 7

Figure 8

Figure 9

Cod (Gadus morhua)

Very few cod larvae were caught this month. The greatest occurrences of larvae were along the southern-southwestern edge of the Bank. The collections made at stations 9 (~2 larvae at 7mm) and 50 (~3 larvae at 5mm) contained the most fish. The rest of the larval occurrences in the survey area were found along the northwestern edge at stations 60, 28, 30, 76 and 34 (one larva at each station). Samples collected at other stations occupied along the northwestern edge of the Bank contained herring larval of approximately 5-8mm length. The largest fish collected (10mm length) was at station 28(Figure 8). Cod larvae collected on this January survey closely resemble the 1996 and 1998 survey results in both larval abundance in that very few larvae were present.

Gadid Eggs (cod/haddock/pollock eggs)

There were more gadid eggs collected on Georges Bank during this January survey than during any of the previous three January cruises. The largest concentrations (~6-50/station) of gadid eggs were found on the Northeast Peak, across the northern channel at station 25, and along the northern edge of the Bank. Gadid eggs were also found at three stations in the Great South Channel(Figure 9). The greatest concentrations of eggs were collected on the Northeast Peak area of the Bank, with some isolated patches of gadid eggs occurring in the Great South Channel and on the northwestern portion of the survey area. The collection results from the January 1998 broad-scale survey closely resemble the catch results from this month.

Miscellaneous Fish Larvae:

The following miscellaneous fish larvae were also identified in the ichthyoplankton samples collected during this broad-scale survey.

Gonostomatidae

Small numbers of these fish were found only at the deep water stations 56, 16 and 57. Station 16 had the greatest estimated number of fish at 5 individuals.

Pollock (Pollachius virens)

Three pollock larvae were seen in the samples examined during this survey. Two specimens were collected along the northern edge of the Bank; one larva (size~10mm) at station 30 and one (size~15mm) at station 74. One other specimen (size ~20mm) was observed at station 79 which is located along the northwestern edge of the Bank(Figure 8).

Hake (Urophysics sp.)

One Urophysics sp. was sampled at station 73 (on the northern edge of the Bank) at a length of 15 mm.

Preliminary Summary of the 10-m2 MOCNESS samples.

(Maria Casas and Stephen Brownell)

The samples collected from 10-m2 MOCNESS were examined on shipboard for a qualitative estimate of abundance, distribution, and size range of both the invertebrate and the fish community at station. The following observations are based on examination of the samples following preservation.

Station 7, Haul 1

euphausiids (lots)

ctenophores

hyperiid amphipods

naked pteropods, Clione spp.

3 medusa (bell size 3cm.)

Station 16, Haul 2

euphausiids

ctenophores

small medusa

2 squid (2cm.)

1 octopus (3cm.)

lantern fish

hake larvae

Station 17 Haul 3

ctenophores

Station 20 Haul 5

12 jars of ctenophores and

pleurobrachia

Station 23 Haul 6

Crangon

pleurobrachia

hyperiid amphipods

Clione

medusa (5 cm.)

herring larvae

windowpane flounder

Station 25 Haul 7

ctenophores

euphausiids

medusa

Station 39 Haul 8

pleurobrachia (lots)

euphausiids

Clione

gammarids

lantern fish (4)

Station 27 Haul 9

pleurobrachia (lots)

euphausiids

Clione

gammarids

Station 29 Haul 10

euphausiids

ctenophores

hyperiid amphipods

large shrimp (6cm)

Clione (lots in the 100 to 40 m net)

lantern fish

Station 32 haul 11

ctenophores (6 jars for net one)

hyperiid amphipods

Clione

Crangon

isopods

Station 40 Haul 13

ctenophores

euphausiids

hyperiid amphipods

Clione

medusa (5 cm)

sand lance larvae

herring larvae

Observations of Zooplankton Collected

(Charles Miller)

Non-quantitative stereomicroscope observations were made of zooplankton collected by the 150 m mesh nets on the 1 m2 MOCNESS(MOC-1) and by other nets during the cruise. All around Georges Bank the total drained volume of the collections was comparable to or greater than in previous January broad-scale studies. We caught less than 300 ml (a teacupful) in all nets, everywhere, but not less than usual. My subjective impression was that we caught somewhat larger amounts than in this month in 1998.

At Station 1 we saw a mixture of species typical around the entire south flank seaward of 100 m. The dominant animal, constituting over half the biomass, was Centropages typicus. These were mature specimens, both males and females. Few copepodites were present. The deeper nets in the MOC-1 profile included abundant Sagitta elegans and epibenthic amphipods (gammarid types). There were substantial numbers of very small Limacina "retroversa". These have been seen everywhere on this cruise, including deep waters at the edge of the Gulf of Maine and right up over Georges Bank. Calanus finmarchicus were present, but very few (3 to 5 in 1/12th examined of each MOC-1 level). Coscinodiscus and Rhizosolenia were present in the sample, but not in massive amounts. They are enough to make the samples appear green in bulk.

Metridia lucens in all copepodite stages was dominant in the deepest haul at Station 41, in deeper water. There were very small numbers of C. finmarchicus at all depths, and Net 1 (90-40m) caught a few C. helgolandicus. I do not recall seeing those on Georges Bank before, and did not see them again this cruise. All nets caught large numbers of mixed small copepods: Oithona, Microcalanus, etc. Pseudocalanus, if present at all, was only small copepodites. Net 2 (40-15m) captured some large adults of Candacia armata, and some Aglantha-like hydromedusae. The catch was sharply distinct from that in Net 1. The surface net included few zooplankton, except the mixture of very small copepod species. Phytoplankton were abundant, producing a very green sample.

The MOC-1 at Station 3 filtered mostly "phytodetritus", a brown mixture of nondescript phytoplankton. Most copepods captured were C. typicus. Small Limacina were abundant in Net 2, replaced by clam larvae in Net 1.

Station 7 in deep water south of Georges Bank was not as exciting zoologically as on most cruises. There were relatively few copepods of any kind in Net 1, but the rank order of species was M. lucens >C. finmarchicus > Euchaeta sp. A few subtropical types were there, too. Few little copepods were captured at depth. Pleuromamma sp. was dominant in Net 2, joined by an abundant mixture of small copepods (Oithona, etc.). Net 3 had almost no sample, mostly tiny copepods and phytodetritus. One-twelfth of the Net 4 sample included about 20 C. finmarchicus ( > > C5, the only predominantly matured sample of the cruise), a few Candacia,

Pleuromamma and phytodetritus. Overall, there were some C. finmarchicus in the slope water, but they did not amount to a large resting stock, dominant in the deep plankton.

Before Station 9 no Pseudocalanus spp. were found at any station, but 9 produced "some", second to very much larger numbers of C. typicus. Pseudocalanus were not seen again until Station 18, where one (only) was spotted. This strong dominance by C. typicus was typical (the pun is accidental) all along the south flank. Station 9 included small amounts (compared to late spring) of Clytia-like hydroids. These were not seen elsewhere on the cruise. Sagitta were abundant in the bottom net.

Up on top of Georges Bank at Stations 11 and 12 the bulk of the plankton was the copepods Centropages hamatus and C. typicus. The former way outnumbered the latter, so we have the typical arrangement usually seen in late spring and later, C. hamatus as the main player inside the well-mixed zone. Both species were present almost entirely as adults. Sagitta were also abundant in the bank-top samples. There was no difference between deep and shallow nets. This combination of two Centropages species and Sagitta is "bank mix". In late spring it will include variable amounts of Clytia, but that has not been seen up on the bank this cruise, only at Station 9. A few Pseudocalanus are usually included, although I didn't see them at 11 or 12.

Samples from Station 16, in deeper water to the south, were not examined in detail, but the deeper samples contained no significant numbers of C. finmarchicus. Again, the slope water does not seem to harbor a significant resting stock at this time.

Samples from Station 18 at the east end of the south flank were mostly phytodetritus. There were a few C. finmarchicus and fewer C. typicus. That is a change, since the latter species was relatively numerous to the west. The deep sample included lots of gammarids-like amphipods and some annelids (long, errant types) and shrimp (Crangon-like). The amphipods remained in Net 2 and were joined by some Parathemisto, but there were none in Net 3. Net 3 had a few Sagitta.

Calanus finmarchicus showed up for the first time in substantial abundance in Stations 25 and 39 on the Scotian Shelf and in Northeast Channel. They were the dominant animal in the deep nets (200+ to 100m). Fifth copepodites were most abundant, followed by males and females. Compared to other years, when 3/4 of the stock had matured by mid-January, all sites this year show less than 1/4 matured, with C5 strongly outnumbering them. Net 2 had few Calanus, but they showed up again in Nets 3 and 4. The three upper nets had numerous small copepods (Oithona mostly).

Station 26 was an oddity. All along up to that point we had caught a few to a few dozen Pleurobrachia in most samples, ranging in size from 0.3 to 2 cm. At 26 all nets (bongo, MOC-1 bottom to top) were loaded with them. Slime associated with them clogged the filter screens. They filled over a liter from every net. It was hard to get any other part of the sample (copepods) out of the slime. Microscope examination showed very little other plankton of any kind, but that may just be due to the separation problem. It was hard to remember working with the samples that these Pleurobrachia were spread through many 10's of cubic meters in the ocean, and thus did not totally occupy the water. At most later stations there were again some Pleurobrachia, but nothing like the 'bloom' at station 26.

Station 29 over Georges Basin had numerous C. finmarchicus in both bottom and top nets, with few between. Most were C5 with some females in the surface. Again, maturation is late compared to earlier years observed. The net wire carried strands from pink siphonophores, but these were only evident in the catch of Net 1 as badly abraded bracts. None were seen in higher nets. Net 1 had some Metridia, Pleuromamma, and Euchaeta with relative abundance in that order. Net 2 caught some Pseudocalanus and C. typicus in a mixture of phytodetritus that included large numbers of Ceratium. These Ceratium at 100-40 meters showed up in later stations at the edge of the Gulf. Net 3 included numerous small Limacina as did Net 4.

At Station 40 Calanus were sparse in Net 1, accompanied by a few Metridia, however there were abundant Calanus, mostly C5 in Net 6. Males were more numerous than females. There were good amounts of Calanus in all the coarse mesh nets at shallower depths, too. Fine mesh Nets 2, 3, and 4 were all dense with green phytoplankton glop (the samples were preserved while I slept, so I could only examine the alcohol series microscopically). Peter Wiebe and I made the following comparison to the MARMAP results:

Carol Meise's Gulf of Maine average Calanus abundance chart here. It shows the Georges Basin area we sample at broad-scale Station 40 (west end of the basin at 183 meters, round to 200 m) in a zone with average January-February copepodite (C5 and adult, we think) abundances between 10^3 and 10^4 per m^2. Our MOC-1 sampled very close to 1000 m^3 over the water column, so at the average seasonal density we should have caught the number expected under about 5 m^2, or between 5000 and 50000. We can't count the samples, but we caught over 300 ml settled volume of mostly Calanus, mostly C5 (some males, very few females), mostly in the bottom net (180-100m), although there were significant numbers right to the surface. Chatting with Maria Casas, who has an experienced counting eye, allows us to guess. The number is on the high end of Meise's contouring range for station 40; the jars contain at least 25,000 and more likely 50,000 C5-C6. For at least this one station, the Gulf of Maine area just adjacent to the bank is not so far from normal (that is to say average). Station 34 in fairly deep water showed a comparable result the next day, at least for Nets 6 to 9. My observation in June 1998 that Calanus abundance in southern Gulf waters was less than other years observed still stands. We never had to split a sample in June 1998 in order to preserve, while in other years we were throwing out 3/4 to 15/16 of samples and still had as much as we saved in 1998. This does not seem to have led to a marked low in 1999 Go stocks in the southern Gulf. Perhaps there is strong density dependence to resting stock mortality.

At Station 34 the Net 1 sample was pulped. Apparently the cod ends were tangled at the time it fished. Higher nets were loaded with phytoplankton, some of it the tiny Ceratium seen at earlier stations. This identification needs confirmation ashore, since the scope was shaking so badly

when I examined the sample that higher powers were useless. Calanus were similar in abundance and distribution to station 40. There were small Limacina well dispersed vertically.

Station 36 up on the Bank and Station 37 at the edge had standard "bank mix", here including Pseudocalanus sp. as a distantly third ranked copepod. Samples were pretty clean, with only a little phytodetritus in those from 150 m mesh.

Station 38 in the south corner of Wilkinson Basin has a substantial stock of large copepods, ca. 300 ml settled volume in 100 m3 , more than 3/4 of which is Metridia, adults and older copepodites, the rest Calanus, mostly C5. Stations 29, 40, and 34 had Metridia, at 38 it was dominant. MOC-1/Net 1 (139-100m) and Net 2 (100- 40m) both have substantial amounts of tissue from siphonphores, badly torn up. Most of the copepod mass was captured well up off the bottom, above 100 m. At this station, I only examined the coarse mesh, ethanol preserved samples.

Summary: The recurring spatial division of zooplankton communities in the Georges Bank region seems to be fully established. That is, we have a Centropages hamatus-dominated "bank mix" inside roughly the 100 m line, and other plankton assemblages outside. This sharp division is a little surprising for January. I'm tempted to suggest they have lasted longer than usual because temperatures are 1-2oC warmer than the mean for the month. Perhaps they have never been swept from the Bank by a strong, winter norwester. Plankton on the south flank are dominated by Centropages typicus, but south flank stations usually also showed a mixture of very small copepods, both calanoids and Oithona.

Calanus finmarchicus are essentially absent from over the Bank, and are a very minor constituent on the south flank. The C. finmarchicus resting stock offshore of the Bank (beyond the 200 m isobath) was minimal to the south, but was of approximately normal abundance in Northeast Channel and at all stations in the Gulf of Maine. A substantial majority of the 1999 Go individuals remained in C5, with less males and many less females. This contrasts with other years, when a majority of C5 had matured by mid-January. There's a clue in that of some kind. Wherever we found Calanus, we also found Metridia lucens. It was usually less numerous than Calanus in C5 and adult stages, but (unlike Calanus) younger copepodites were also present.

Pseudocalanus spp. were few everywhere, with largest numbers in shallow water over the northwest part of the Bank. Those recognized were all adults. Limacina "retroversa" were present in virtually all stations, occasionally very numerous but always very small. In samples they look and behave like sand. On the whole they were more abundant in mid-depth samples, not at depth and not in the 0-15 m samples.

Nutrients and Phytoplankton Studies

(Keska Kemper and Regina Pfistermeuller for David W. Townsend

University of Maine)

[see also: http://grampus.umeoce.maine.edu/globec/globec.html]

Overview:

We are collecting water samples on all six broad- scale cruises in 1999 (January to June) to analyze for a suite of nutrients and phytoplankton biomass. During this cruise, water samples were collected for analyses of: