We appreciate and acknowledge the efforts and professionalism of the officers and crew of the R/V OCEANUS. Their dedication and cooperation made the success of this cruise possible.
This cruise was sponsored by the National Oceanographic and Atmospheric Administration and the National Science Foundation. This report was prepared by all members of the Scientific Party on this cruise (see Appendix A).
TABLE OF CONTENTS
Purpose of the Cruise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Sampling Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Cruise Narrative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Hydrography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Phytoplankton Chlorophyll, Nutrients and Light Attenuation Studies . . . . . . 8
Summary of Zooplankton Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Summary of Ichthyoplankton Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Summary of MOC-10 Ichthyoplankton Samples . . . . . . . . . . . . . . . . . . . . . . 13
Microzooplankton Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Summary of Operations and Samples Collected . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Appendix A. Personnel List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Appendix B. Event Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Appendix C. Hydrographic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
PURPOSE OF THE CRUISE
The cruise aboard the R/V OCEANUS (OC317) was the second in a series of six Broad Scale surveys that will be conducted monthly from January to June during 1998 to monitor the changing biological and physical status in the Georges Bank ecosystem. These six cruises are the fourth year of broad scale surveys conducted as part of the U.S. GLOBEC Georges Bank Program. The personnel who participated in this cruise are listed in Appendix A.
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 is 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 and feeding habits.
(3) conduct a hydrographic survey of the Bank
(4) conduct a survey of chlorophyll and nutrient levels on the Bank
(5) map the Bank-wide velocity field using an Acoustic Doppler Current Profiler
(6) compare two plankton pumping systems in their sampling of N1 stage copepods
(7) collect samples for population genetic studies of Pseudocalanus spp.
(8) deploy satellite tracked drifters for the study of the currents on the Bank.
The plan for the GLOBEC Broad Scale surveys is to accomplish the objectives above by sampling at a grid of 41 "standard station" locations which covers the entire bank (Figure 1b). The Broad Scale sampling protocol separates these 41 stations into two groups, full stations and partial stations. At the 20 full stations, a complete set of sampling operations is conducted. This involves a double-oblique bongo net tow, a CTD cast with rossette collection of water samples, a 1-m2 MOCNESS (Multiple Opening Closing Net Environmental Sampling System , MOC-1) tow, a plankton pump cast and a 10-m2 MOCNESS (MOC-10) tow. At the partial stations only the bongo tow, CTD cast and MOC-1 tow are done. Additional bongo net tows were made en route between the standard stations to increase the sampling density for cod and haddock larvae. Current measurements also were collected continuously by a hull mounted 150 kHz Acoustic Doppler Current Profiler (ADCP).
Bongo tows were made with a 0.61-m frame fitted with paired 335 mm 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 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 mm mesh nets were rinsed with seawater into a 335 mm 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 either was not towed or could not be used due to adverse weather conditions, a second bongo tow was made. This frame was fitted with both 335 mm mesh and 200 mm 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 mm mesh sample was retained for zooplankton species composition, abundance and distribution, and preserved in 10% formalin. The other sample (335 mm 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 mm mesh for the collection of older and larger copepodite and adult stages of the zooplankton. Nets 0, and 5-9 were fitted with 335 mm 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 500 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 mm 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 mm 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, 90-ml subsamples from the bottom and surface 150 mm mesh nets were removed and preserved in 10% formalin for Dr. C. Miller (OSU). At priority 1 and 2 stations, 90-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. At stations deeper than 150 m where C. Miller required subsamples for live analysis, the 1-m2 MOCNESS was hauled out after the first oblique. Samples from nets 0-4 were collected and the MOCNESS was then immediately redeployed to complete the tow.
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 335 mm mesh, and preserved in 10% formalin.
The Pacer high-volume pump was used to collect nauplii and younger, smaller copepodite stages of zooplankton. The intake hose was deployed off the port side by connecting the suction end, fitted with a 1.7-L Niskin bottle cut in half lengthwise, to the boom 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. Three 30-m sections of 7 cm diameter hose were connected to the pump, allowing the intake hose to attain a maximum depth of approximately 75 m. At shallow stations, the intake hose nozzle was lowered to 3-5 meters off the bottom. Three integrated depth samples were collected with 35 mm mesh nets, sieved through a 30 mm mesh sieve and preserved in 10% formalin. Sampling depths were from the maximum depth to 36 m, 36-11 m, and from 11 m to surface. Before samples were collected, water was diverted from the net and the hose was allowed to flush for 60 seconds. This assured that the zooplankton from the desired strata was obtained. Once at the surface, the intake section was held just below the surface for 60 s. This allowed the water to pass completely through the hose. Wire retrieval rate was approximately 4 m/min. This rate was used to obtain volumes of 500 L per 5 m depth interval sampled.
At stations 18, 20, and 29 a pneumatic diaphragm pump was used simultaneously with the Pacer high-volume pump. This was performed in addition to the standard pump protocol in order to determine if either pump is more effective in collecting N1 and N2 naupliar stages of copepods. The pneumatic pump used 3.1 cm hose and was deployed along side the 7 cm hose of the Pacer pump. A brass clip on the Pacer pump intake hose was clipped to a shackle on the pneumatic pump hose so that the intakes for both hoses were at nearly the same depth. The hoses were then deployed together using the protocol for the Pacer pump described above. Samples were collected simultaneously at one depth (15 m at station 18, 20 m at stations 20, 29) for 12 minutes using 35 mm mesh nets, one net per pump. The samples were then sieved through a 30 mm mesh sieve and preserved in 5% formalin.
The primary hydrographic data were collected using a Neil Brown Mark V CTD instrument (MK5), which provides measurements of pressure, temperature, conductivity, fluorescence and light transmission. The MK5 records at a rate of 16 observations per second, and is equipped with a rosette for collecting water samples at selected depths. In addition a Seabird Electronics Seacat model 19 profiling instrument (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 MK5 was deployed with 10 bottles on the rosette and samples were collected for various investigators. On each MK5 cast, samples were to be collected for chlorophyll/nutrient analysis (see Individual Report section below), for oxygen isotope analysis by R. Houghton (LDGO) and a sample was taken at the bottom for calibrating the instrument's conductivity data. At selected "full" standard stations water samples were collected for micro-zooplankton analysis for S. Gallager (WHOI). Surface samples for phytoplankton species composition were collected for J. O'Reilly (NMFS) at the "full" standard stations.
Sailing was delayed one day due to weather. The cruise departed Woods Hole at 0915 on Saturday, February 7 and arrived at the first station at 2130. No significant problems were encountered and the routine of sampling operations were quickly established. Many in the scientific party had been on 10 or more of the Broad Scale survey cruises, and efficient team work occurred without direction. On standard station 2 the MOC-1 hung up on the bilge keel near the end of the tow, but suffered only minor damage - no data or samples were lost. Adverse weather conditions caused MOCNESS and pump operations to be dropped as standard stations 3 and 4, where only two bongo tows and a CTD cast were done. On Friday, February 13, operations were secured for ten hours at standard station 39 due to weather.
After standard station 25 the CTD cell on the MK5 instrument was rinsed with alcohol and stored dry between stations because of freezing temperatures. During the CTD cast at station 26, the conductivity signal was near 0. Air temperatures had warmed a bit and the cell was stored in freshwater en route to standard station 27, where the conductivity data appeared correct. The upper 25m of the cast at standard station 28 also had near zero conductivity values, but the values quickly increased to normal during the rest of the cast. The conductivity data appeared correct for the rest of the cruise. The MK5 and SeaCat instruments agreed to within about 0.01 salinity unit. Whether rinsing in alcohol caused the conductivity data problem is not known, although this procedure had been used in the past without problem.
En route to standard station 30, during rough wind and sea conditions, a wave came over the starboard rail and bent the bars on the MOC-1 frame. These bars were replaced with another set, which themselves were bent slightly by another wave, even while strapped to the deck away from the rail. The replacement/repair activities required about eight hours of work on deck in air temperatures of about -8 C, and winds which made the wind chill well below zero. The replacement bars functioned well and no loss in sampling resulted from the damage. At standard station 30, only two bongo tows were accomplished because of continued adverse conditions.
A total of one CTD cast, three pump operations, three MOC-1 tows and six MOC-10 tows were canceled because of weather. Throughout the cruise a total of 3 MOC-1 cod end buckets were broken or lost. Two MOC-10 buckets were lost and one was broken. No other equipment problems or damage occurred during the cruise.
A list of the sampling operations and other events on the cruise is presented in Appendix B.
Station numbers referred to in the following reports are standard station numbers (figure 1a), unless otherwise noted.
(David Mountain and Cristina Bascunan - NMFS, Woods Hole)
The SBE19 Profiler and the MK5 data were post-processed at sea. The Profiler data were processed using the Seabird manufactured software: DATCNV, ALIGNCTD, BINAVG, DERIVE, ASCIIOUT to produce 1 decibar averaged ASCII files. The raw MK5 data files were processed using the manufacturer's software CTDPOST in order to identify bad data scans by "first differencing." The latter program flags any data where the difference between sequential scans of each variable exceed some preset limit. The "Smart Editor" within CTDPOST was then used to interpolate over the flagged values. The cleaned raw data were converted into pressure averaged 1 decibar files using algorithms provided by R. Millard of WHOI, which had been adapted for use with the MK5.
Figure 1a shows the locations of the MK5 casts made the bank-wide survey, identified by the consecutive cast number. The surface and bottom temperature and salinity distributions are shown in Figures 2 - 3. Surface and bottom anomalies of temperature and salinity as well as a stratification index (sigma-t difference from the surface to 30 meters) were calculated using the NMFS MARMAP hydrographic data set as a reference. The anomaly distributions are shown in figures 4-6. The distributions of surface and bottom measured fluorescence are shown in figure 7. Profiles of each MK5 CTD cast with a compressed listing of the preliminary data are found in Appendix C.
The volume average temperature and salinity of the upper 30 meters were calculated for the four sub-regions of the Bank shown in Figure 8. These values are compared with characteristic values that have been calculated from the MARMAP data set for the same areas and calendar days.
The low salinity conditions observed in 1996 and 1997 have continued into 1998. The January survey results suggested that the salinity might be returning toward near 'normal' values. However, the anomaly values on the northern half of the Bank in February, listed in Figure 8, are about 0.5 salinity units lower than observed on the January 1998 survey. No major intrusions of Scotian Shelf or Slope waters onto the Bank were observed. Satellite imagery indicated that a tongue of Scotian Shelf water was extending westward just off the southern edge of the Bank. The surface salinity at station 16 (the off bank most station) was <32 PSU, confirming the presence of Scotian Shelf water south of the Bank. Much of the southern flank of the Bank was 1 to 2 C colder than expected (Figure 3), which likely results from an influence of Scotian Shelf water in the area. The only stratification observed was located along the eastern and southeastern edge of the Bank (Figure 6), due primarily to low surface layer salinities. The fluorescence was low across the Bank (Figure 7), with values about half of those observed in January. The Bank-wide average fluorescence was the lowest observed on any Broad Scale survey.
Phytoplankton, Chlorophyll, Nutrients and Light Attenuation Studies
(David W. Townsend, Jiandong Xu and David Cole - University of Maine)
Water samples were collected during the February 1998 R/V Oceanus Broad Scale survey cruise to Georges Bank for the analysis of:
dissolved inorganic nutrients (NO3+NO2, NH4, SiO4, PO4);
. dissolved organic nitrogen and phosphorus;
. particulate organic carbon, nitrogen and phosphorus, and
. phytoplankton chlorophyll a and phaeophytin
Only the chlorophyll data are reported here; other data can be found on our web site:
Collections were made at various depths at all of the regular hydrographic stations (Stations 1 - 40) sampled during the February 1998 broad scale survey cruise aboard R/V Oceanus, using the 1.7 liter Niskin bottles mounted on the rosette sampler. Additional surface water samples were collected at positions between the regular stations (Stations 41 - 81) using a Kimmerer Bottle to sample a depth of 2m.
Light attenuation of photosynthetically active radiation (PAR) was measured at several stations at or about noon when sea state conditions allowed. A LiCor underwater spherical quantum sensor and deck-mounted cosine quantum sensor were used to compare the underwater light field as a function of depth and coincident surface irradiance.
Samples for dissolved inorganic nutrients and chlorophyll were collected at all stations, 1-81. Water samples for DIN were filtered through 0.45 mm Millipore cellulose acetate membrane filters, and the samples frozen immediately in 20ml polyethylene scintillation vials by first placing the vials in a seawater-ice bath for about 10 minutes. Samples will be analyzed on shore immediately following the cruise using a Technicon II 4-Channel AutoAnalyzer.
Water samples (50 mls) for dissolved organic nitrogen, and total dissolved phosphorus were collected at 2 depths (2 and 20m) at each of the main stations and frozen as described above. These samples will be analyzed ashore using a modification of the method of Valderrama (1981).
Samples for particulate organic carbon and nitrogen were collected by filtering 500 mls from 2 depths (2 and 20m) at each of the main stations onto pre-combusted, pre-ashed GF/F glass fiber filters, and filters frozen for analysis ashore. The filters will be fumed with HCl to remove inorganic carbon, and analyzed using a Control Equipment Model 240-XA CHN analyzer (Parsons et al., 1984).
Samples for particulate phosphorus were collected as for PON (but 200 mls will be filtered) and frozen at sea. Laboratory analyses will involve digesting the sample in acidic persulfate and then analyzing for dissolved orthophosphate.
Phytoplankton chlorophyll a and phaeopigments were measured on discrete water samples collected at all stations (see Table 1) and determined fluorometrically (Parsons et al., 1984). The extracted chlorophyll measurements involved collecting 100ml from all bottle samples taken at depths shallower than 60m, filtering through GF/F filters, and extracting the chlorophyll in 90% acetone in a freezer for at least 12 hours. The samples were analyzed at sea using a Turner Model 10 fluorometer. These data will be used in regressions against measurements of in situ fluorescence as part of the regular CTD casts.
Parsons, T.R., Y. Maita and C.M. Lalli. 1984. A Manual of Chemical and Biological Methods for Seawater Analysis. Pergamon, Oxford. 173 pp.
Valderrama, J.C. 1981. The simultaneous analysis of total nitrogen and total phosphorus in natural waters. Marine Chemistry 10: 109-122.)
Summary of Zooplankton Studies.
(Jennifer Crain - Oregon State University)
Calanus life history studies - On Broad Scale cruise OC317, I continued to gather data on correlations between gonad development, oil sac volume, and tooth phase in Calanus finmarchicus fifth copepodites. We have observed that Calanus juveniles which are preparing for diapause tend to have smaller, less developed gonads than those in the process of maturing directly into adults. Small, not well defined gonads were typical among C5's examined in the first sampling of this series, in May of 1997. By contrast, in January of 1998, as the recently emerged resting stock of C5's was getting ready to molt into adults, nearly all of the individuals sampled had a large, well-developed gonad, often with the oviducts easily distinguishable. Most of these animals were recognizably female, with only one or two gonads identified as possible testis. Observations of C5 gonads from the present cruise are virtually identical to those made in January.
Nearly the entire Calanus stock has matured, with egg-laden females predominating in the population. Very few Calanus copepodites were seen on OC317. Live sorting was done of samples from deep and shallow nets at standard stations 7,13,18,22,34 and 38. The few C5's that were found, probably stragglers from the resting stock, were either from the surface near the 40 m isobath or the deep nets of MOCNESS tows taken outside the 100m isobath. Images were captured of individual C5's from stations 13,18, 22 and 34 (no C5's were found at the other stations sorted), and oil sac volumes were calculated from areal measurements using image
analysis software. Observations on the developmental status and length of each animal's gonad were made. As in January, almost all of the fifth copepodites had large, well developed gonads. The overwhelming majority of these were ovaries complete with developing oviducts, with only a few specimens displaying the blockiness characteristic of maturing testis and only two bearing
what appears to be a rudimentary vas deferens. Each animal was individually preserved in formalin for later verification of field observations of the gonads using differential interference
contrast microscopy. Correlations between gonad development and oil sac volume will be assessed with respect to relative age-within-stage, as evidenced by tooth phase.
On this cruise I also continued to collect formalin-preserved subsamples from the 150 micron-mesh MOC-1 nets at all priority 1 and 2 stations for ongoing studies of jaw phase
distributions and possible secondary environmental sex determination in Calanus finmarchicus. Ethanol-preserved subsamples were taken from MOC-1 net 5 at the same stations, to be
used for molecular determination of the underlying genetic sex of individual Calanus.
Synopsis of zooplankton observations made after preservation:
Coscinodiscus abundant all over and around the Bank, especially at shallower stations; pteropods present in moderate numbers, especially at stations along the southern flank, densest between 15 and 40 m; siphonophores present at many, especially southern, stations, fewer at Northern stations; Calanus females, full of eggs, abundant; Some Calanus males; Very few Calanus copepodites, with some C1-C3's found outside the 40 m isobath on the southern flank, and a number of C5's at depth at stations 16 and 34; Calanus and/or Pseudocalanus nauplii seen throughout.
Station 1: Not much biomass. Lots of chaetognaths, some euphausiids and a few adult Calanus.
Station 2: Lots of diatoms in 150 micron nets. 335 micron nets had a lot of adult Calanus (mostly female), Centropages, some chaetognaths, a few amphipods, and many of pteropods.
Station 41: Low biomass. Bongos C and D done in place of a MOC-1 cast. Much phytoplankton in the 200 micron mesh net (net D), also chaetognaths, pteropods, some adult Calanus and Centropages.
Station 3: Mostly Coscinodiscus.
Station 4: Mostly Coscinodiscus, some pteropods, chaetognaths and euphausiid larvae, a few adult Calanus.
Station 7: Lots of Coscinodiscus, some chaetognaths, Pseudocalanus adults and copepodites, a few Metridia, a few Centropages, a few Calanus C3's, C4's, one or two C5's.
Station 9: Siphonophore glop, some Metridia and Pseudocalanus a few Calanus adults, almost all females, a bunch of young Calanus copepodites (C1-C3's), very few older copepodites. Lots of diatoms in 150 micron nets.
Station 10: Mostly Coscinodiscus, few Calanus, and some pteropods.
Station 12: A few Calanus adults (females), a few Pseudocalanus, lots of Coscinodiscus in samples from the 150 micron nets.
Station 13: Many adult and copepodite Metridia in the sample, as well as some pteropods, a few Centropages, chaetognaths, and lots of diatoms.
Station 16: Chaetognaths, Myctophids, Euchaeta, shrimp, euphausiids, Metridia, Calanus females and males, many Calanus C5's.
Station 17: Lots of Coscinodiscus, adult female Calanus, a few Pseudocalanus.
Station 18: Lots of phytoplankton and syphonophore glop, pteropods, Metridia, a few Centropages.
Station 20: Lots of siphonophore glop and Coscinodiscus, some chaetognaths, Pseudocalanus, a few Centropages, almost no Calanus.
Station 23: Siphonophore glop, some Pseudocalanus and Centropages, a lot of adult female Calanus, a few adult males, some younger Calanus copepodites (C1-C3), Calanus C5's nearly absent.
Station 39: Lots of siphonophore glop, lots of adult Calanus, especially females, almost no Calanus copepodites, a lot of fish eggs, a few Centropages.
Station 25: Chaetognaths, siphonophore glop, lots of Metridia, some Calanus adults, few Calanus copepodites, some Pseudocalanus.
Station 27: Chaetognaths, Pseudocalanus and Centropages adults and copepodites, some Calanus adults, mostly females, a few Calanus C4's and C5's, a few hydroids.
Station 29: Lots of Euchaeta, some Metridia, some Calanus adults and a few C4's and C5's, amphipods.
Station 30: Low biomass. Some chaetognaths and Centropages, almost no Calanus.
Station 40: Lots of Centropages, copepodites and adults, some Metridia, some Calanus (mostly females and a few older copepodites, a few males)some Pseudocalanus.
Station 36: Mostly Coscinodiscus.
Station 38: Mostly Coscinodiscus, some Metridia, some adult Calanus, almost no Calanus copepodites.
Summary of Ichthyoplankton Studies
(Antonie Chute, John Sibunka and Stephen Brownell)
The samples collected at 41 GLOBEC Broad Scale stations from both the bongo and 1-m2 MOCNESS and from the bongo at the intermediate bongo stations were examined shipboard for the presence of fish eggs and larvae. The samples were preserved, and were observed while in the jar with the aid of a magnifying glass. This was done in an attempt to obtain a qualitative estimate of abundance, distribution and size range of ichthyoplankton on Georges Bank. The following observations are based on examination of samples in the jars following preservation. Preliminary estimates of the distributions of cod/pollack larvae, haddock larvae, cod/haddock eggs, sand lance larvae and herring larvae are shown in Figures 9 - 11.
Cod (Gadus morhua) and/or pollock (Pollachius virens):
Catches of both larval cod/pollock and cod/pollock/haddock eggs during last month's cruise were light, indicating that spawning on the Bank was just getting under way. This cruise, catches were large in comparison to last month, with some samples containing up to ~30 newly-hatched larvae. Cod/pollock larvae or juveniles were observed at 43 out of 80 stations scattered widely over the Bank, but the largest catches occurred on the northern half in three general areas: the Northeast Peak, the shoal water around standard stations 11 and 12, and off the Bank, north of the Great South Channel around standard station 38. Most of the larger catches consisted of smaller larvae, those between 5 and 8mm, but larvae greater than 10 and up to 16mm were consistently observed in samples from every area of the Bank. An interesting aspect of this month's cod/pollock catch was this apparent lack of a spatial pattern in terms of larval size. Last February, the larvae were found to be smallest near the Northeast peak and on the southern half of the Bank, and larger on the northern half, as if they were spawned on the Peak and had moved clockwise with the gyre as they grew. This year, large and small larvae were found together on both halves. The concentration of cod/pollock/haddock eggs and larvae north of the Great South Channel (standard station 38) may represent another spawning area, which could contribute to the eggs and larvae already on the Bank and create this more complex pattern.
Haddock (Melanogrammus aeglefinus):
The very few haddock seen in the samples (~30 larvae) were observed at 5 stations forming a line from off the Bank, north of the Great South Channel (standard station 38) to the Northeast Peak. All the larvae seen were under 10mm, and the largest catches were observed at bongo station 54 (~9 larvae) and standard station 38 (~6 larvae), where substantial catches of cod/pollock larvae were also observed.
Atlantic Herring (Clupea harengus):
Catches of herring were very similar to the catches from last February. The bulk of the catch was from the northwestern quadrant of the Bank, centered around standard station 36 (~115 larvae), and in the Great South Channel (~40 larvae at standard stations 1 and 2). A few herring were also observed from Gulf of Maine stations 29 and 34. Like last month, no herring larvae were observed on the eastern or central portions of the bank.
Sand lance (Ammodytes sp.):
The catches of sand lance show a more northerly distribution than usual. Interestingly, the area of highest sand lance concentration in February both this year and last year is the same (standard station 37), but the typical shoal water distribution (middle of the Bank) was not evident this year. Instead of southeast of station 37, the sand lance were found northeast of station 37. Sand lance were observed in samples from the Northeast Peak and northern half of the Bank only. Catches were light (less than 5 larvae) as we moved up toward the Northeast Peak and then became larger and larger as we sampled towards station 38, averaging more than 50 larvae per station in the northwest quadrant.
Catches of cod/pollock/haddock eggs were quite large compared to last month, indicating spawning has accelerated, especially on the Northeast Peak where catches of thousands of eggs were not unusual. Eggs were also observed in high numbers around standard station 38, off the Bank and north of the Great South Channel. At stations between these two areas, egg catches were light but consistent. The southwest quadrant of the Bank was the only area where cod/pollock/haddock eggs were not seen.
Summary of the 10-m2 MOCNESS samples.
The 10 m2 MOCNESS was deployed 14 times during the cruise, and sample sizes were generally small; the preserved sample volume was rarely more than half a quart jar per net. Below is a brief summary of catches per station, based on observations of preserved samples in jars. Taxonomic categories are therefore mostly quite broad, as accurate determination of genus or species often requires microscopic examination. The catches are listed in descending order of biomass.
Standard Station 7, Haul 1
Mixed ctenophores (both pleurobrachia and mnemiopsis types)
Large chaetognaths such as Sagitta inflata
Standard Station 9, Haul 2
3 Juvenile ocean pout (Macrozoarces)
Caprellid amphipods (~15)
Station 12, Haul 3
Very large, smooth worms (~25cm)
5 cod/pollock larvae/juveniles
Station 13, Haul 4
Siphonophores (2 quart jars each net)
Mixed amphipods (both Gammarid and Hyperiid)
Larval herring (Clupea harengus)
Station 16, Haul 5
Shrimp, carapace 10-15mm
Adult lanternfish (Myctophidae)
Standard Station 17, Haul 6
Standard Station 18, Haul 7
Ctenophores (Pleurobrachia type)
Juvenile ocean pout
Razor clam, 15mm
Standard Station 20, Haul 8
Hyperiid and Caprellid amphipods
Standard Station 27, Haul 9
2 juvenile longhorn sculpin (Myoxocephalus)
4 larval/juvenile cod/pollock
Few herring larvae
Standard Station 40, Haul 10
Very large shrimp
Standard Station 32, Haul 11
15-20 larval herring
Sticks, straw and grass
Standard Station 34, Haul 12
Very large shrimp
3 larval/juvenile cod/pollock
10 herring larvae
Standard Station 36, haul 13
Larval/juvenile herring (~200)
Juvenile rock gunnel (Pholis)
Juvenile ocean pout
Standard station 38, Haul 14
Microzooplankton Analysis - The Importance of Microzooplankton in the Diet of Newly Hatched Cod Larvae: Broad Scale Studies of Prey Abundance.
(Shannon Houle and Jason Kelley for Scott Gallager - WHOI)
One objective of this study is to characterize seasonal changes in the potential prey field for newly hatched cod larvae with respect to prey motility patterns and the prey size spectrum.
Purpose: To observe, record and analyze motility patterns and size spectrum of available prey from three locations in the water column- near bottom, pycnocline, and upper well-mixed area at all Broad Scale stations from January through June.
General Procedure: Water samples are collected from the near bottom, and pycnocline areas of the water column using Go-Flo bottles on the Neil Brown Mark V CTD. Surface samples are collected with a plastic bucket. Go-Flo bottle samples are collected by gently siphoning from the top of the bottle instead of the normal port so that microplankton are not disrupted. Tissue culture flasks (200-ml) are filled after being dipped in soapy water and air dried to prevent fogging. To further prevent fogging as well as maintaining a constant low temperature, flasks are transferred to an incubator at 5 C immediately after filling.
Each flask, in turn, is placed in a holder across from a B/W high-res Pulnix camera fitted with a 50 mm macrolens and directly in front of a fiber optic ring illuminator fitted with a far-red filter. This apparatus is suspended within the incubator by bungee cord to reduce vibration produced by the ship. Recordings are made using a Panasonic AG1980 video recorder with SVHS formatted cassettes, a Panasonic TR-124MA Video Monitor, and a timing device for a period of 15 minutes for each sample. The flask is then replaced with the next sample and recordings continue. The field of view is set to ~10 mm.
Each priority #1 station was analyzed; samples were recorded and preserved in 10% Lugols solution. Water samples from priority #2 stations were recorded but not preserved.
Post cruise processing: Motility patterns will be analyzed with the Motion Analysis EV system. The final output will be particle size distribution and a motility spectra associated with each particle. This will be compared with species composition in the microzooplankton fraction preserved in Lugols solution.
SUMMARY OF OPERATIONS AND SAMPLES COLLECTED
The following is a list of the data and samples collected during CTD operations:
Instrument # Casts
SBE19 Calibration 8
Parameter # Samples
MK5 conductivity calibration 40
Oxygen isotope 128
Species Composition 10
The following is a list of the samples Collected by the Zooplankton and Ichthyoplankton Groups:
Gear Tows Number of Samples
1. Bongo nets, 0.61-m 83 tows 80 preserved, 5% formalin
335-mm mesh 83 preserved, EtOH
200-mm mesh 3 preserved,10% formalin
2. MOCNESS, 1-m2 38 tows
150-mm mesh 150 preserved, 10% formalin
335-mm mesh 153 preserved, EtOH
3. MOCNESS, 10-m2 14 tows
3.0-mm mesh 45 preserved, 10% formalin
4. Pump 18 profiles:
35-mm mesh (15 standard) 56 preserved, 5% formalin
( 3 comparison)
Table 1. Chlorophyll data for February 1998 R/V Oceanus GLOBEC Georges Bank Broad Scale Survey Cruise
Table 1. Chlorophyll data for February 1998 R/V Oceanus GLOBEC Georges Bank Broad Scale Survey Cruise (continued)
Table 1. Chlorophyll data for February 1998 R/V Oceanus GLOBEC Georges Bank Broad Scale Survey Cruise (continued)
Table 1. Chlorophyll data for February 1998 R/V Oceanus GLOBEC Georges Bank Broad Scale Survey Cruise (continued)
Officers and Crew of the R/V OCEANUS
Lawrence Bearse Master
Courtenay Barber III First Mate
Anthony Mello Second Mate
Richard Morris Chief Engineer
Alberto Collasius, Jr. Engineer
Kevin Kay Engineer
Jeffrey Stolp Boatswain
Horace Mederiros Able-Seaman
Chris Griner Able-Seaman
Patrick Pike Ordinary-Seaman
Brian O'Naullain Steward
Jovinol Fernandes Jr. M/A
Jan Zelag Marine Technician
David Mountain (Chief Scientist) NMFS, Woods Hole, MA
Cristina Bascunan NMFS, Woods Hole, MA
Antonie Chute NMFS, Narragansett, RI
John Sibunka NMFS, Sandy Hook, NJ
Stephen Brownell NMFS, Narragansett, RI
Jennifer Crain OSU, Corvallis, OR
David Nelson URI, Narragansett, RI
Jim Gibson URI, Narragansett, RI
Jamie Pierson URI, Narragansett, RI
Anna Thompson URI, Narragansett, RI
Riley Young URI, Narragansett, RI
Jiandong Xu UM, Orono, ME
David Cole UM, Orono, ME
Shannon Houle MMA, Bourne, MA
Jason Kelly USCG, Seattle, WA
The event log for cruise OC317 is contained on the following pages.
Summary of hydrographic data.