EN319 CRUISE REPORT

21 February - 4 March, 1999

 

Acknowledgments: We wish to thank the crew of the R/V Endeavor for their professionalism and friendly support. Their cooperation and assistance made the success of this cruise possible.

This cruise was sponsored by the National Science Foundation and prepared by Ted Durbin, Jeff Runge, Melissa Wagner, and Barbara Niehoff.


TABLE OF CONTENTS

Introduction............................................................................3

Cruise Narrative.....................................................................4

Hydrography..........................................................................5

Chlorophyll and Nutrients....................................................13

Zooplankton Abundance.......................................................15

Egg Production Studies.........................................................25

List of Scientific Personnal....................................................26

Event Log...............................................................................27

 

INTRODUCTION

The objective of the cruise was to determine egg production and growth rates, and physiological condition and mortality rates of the dominant copepod species on Georges Bank including the target species Calanus finmarchicus and Pseudocalanus. The general plan was to deploy ARGOS-tracked drogues on the NE Peak of Georges Bank and follow these for 8-10 days. Each day we planned to carry out a CTD and bottle cast (for chlorophyll a determinations) next to the drifter and sample the zooplankton with a plankton pump (5 replicate profiles) and a bongo net (3 profiles). At the same time we planned to carry out molting rate and egg laying rates on the Calanus finmarchicus. From these measurements we planned to determine stage specific mortality rates of Calanus using the population surface method and the vertical life table approach. At the beginning of the drifter deployment and every other day subsequently we planned to carry out a 1 m2 MOCNESS tow to collect potential invertebrate zooplankton predators. Prior to deployment of the drifters we planned to carry out several CTD and bongo transects in an east-west direction between the 60 and 200m depth contours on the NE Peak. Information from these transects was intended to enable us to determine a suitable location for deployment of the drifters.

Following the drifter tracking study we planned to carry out a study of the abundance, stage and depth-distribution of Calanus, as well as determining egg laying rates and physiological condition, along transects in the Gulf of Maine. The objective was to determine the reproductive status of the overwintering Calanus population in the Gulf of Maine prior to the occurrence of the spring phytoplankton bloom. The first transect was planned to begin on the NE Peak and extend north to Maine Coastal waters adjacent to Mt. Desert Island. The second was to extend west across the Gulf to Cape Cod Bay. At each station we planned to deploy the CTD and collect water for chlorophyll a, carry out MOCNESS and pump deployments, and collect live animals for experiments. Stations were to be approximately 30 miles apart.

Because of extremely bad weather throughout the cruise with a succession of storms passing through we were unable to achieve most of these objectives. The cruise was initially delayed several days because of weather. When we reached the NE Peak of Georges Bank to begin the initial transects conditions were too rough to work. A major storm was forecast so we left to shelter in Portland, Maine. At this stage there was insufficient time to complete the planned drifter study. On returning from Portland we carried out a transect across the Gulf of Maine from Maine coastal waters at the mouth of Penobscot bay, across Jordan and Georges Basins, and onto Georges Bank, sampling zooplankton with a pump and Mocness, carrying out egg laying experiments, collecting animals for RNA/DNA measurements, and measuring growth and molting rates. This transect was also interrupted by weather. At the end of the transect we planned to carry out several diel studies of Calanus egg laying on Georges Bank. Bad weather prevented even these limited objectives so we returned to Narragansett.

Although most of our initial objectives were not met, we considered that the N-S Gulf of Maine transect provided useful and new information for this region during the winter.

 

CRUISE NARRATIVE

We left GSO on Sunday, 21 February at 09:15 after a two delay due to bad weather. We proceeded out through Buzzards Bay, Cape Cod Canal and to our station on the NE Peak of Georges Bank, arriving at the station at 08:00 am on the 22nd. Shortly before we arrived winds picked up to over 30 kts, gusting up to 40, and after readying the CTD for deployment we decided that conditions were too severe to start work. We began jogging slowly. Winds were predicted to remain between 30-40 for the rest of the day and we didnt expect to begin work until early Tuesday.

On Tuesday morning winds were still blowing around 30 kt and air temperatures were -7.0 C. However, winds were slowly decreasing so we turned around (during the storm we had jogged about 25 miles N of the station) and steamed back to the station (St 1), arriving there around 13:30. We carried out a CTD cast collecting water for chlorophyll. We then carried out two live tows with a 156 m, 1 m diameter net towed between the surface and near the bottom (47 m). Conditions during the casts were marginal and it would not have been possible to carry out either a 1 m2 MOCNESS tow or a plankton pump cast. At the end of the station the Captain came down with news of more bad weather predicted for the Gulf of Maine and Georges Bank (storm level winds) beginning Wednesday night and wanted to break off work and head into shelter. Portland, Maine was decided upon since we felt it would provide an opportunity to carry out a transect from N to S in the Gulf of Maine as we returned to Georges Bank.

The live tows, meanwhile, were immediately sorted for Calanus and Pseudocalanus adult females and Calanus older stage copepodites. Groups of Calanus were preserved for RNA/DNA measurements. Additional females were sorted for egg laying measurements (Runge/Joly) and to lay eggs for the production of nauplii which would be used when we return to the bank in feeding experiments (Sandrin). Calanus was quite sparse at the station. Other copepods present included Metridia, Pseudocalanus, Oithona and Centropages.

We arrived in Portland on 24 February and departed at 06:00 on the 27th and headed out to the first station of our N-S Gulf of Maine transect off Manincus Island at the mouth of Penobscot Bay. The general approach at each station was to carry out a CTD and collect samples for nutrients and chlorophyll a, do a 1 m2 MOCNESS and a pump cast, and then collect live animals for sorting for egg laying experiments with Calanus and Pseudocalanus. At each station a 75 m mesh net tow was preserved for egg ratio estimates of egg production by Pseudocalanus. Subsamples were taken from surface and deep MOC nets for RNA/DNA and C & N measurement on older stager copepodites and adult females of Calanus. At every other station Calanus nauplii were sorted for RNA/DNA.

The weather was great for two days and we completed two stations (St 2 and 3) the first day and then broke of for the night so that we could collect live animals during daylight at St 4. At St 2 we were in the lower salinity Maine Coastal Current. Calanus was present, both adults and nauplii, as well as Metridia and two spp of Pseudocalanus. At St 3 there were fewer Pseudocalanus and Calanus, but large numbers of Metridia. St 4 was started first thing in the morning and we completed 5 and 6 during the day. There was much large Rhizosolenia at these stations and appeared to be fewer Calanus nauplii. By evening the wind was picking up and since it was predicted to blow 30-40 kts overnight and the next morning we stowed everything on deck away. The next morning (March 1st) was warm with the wind between 20 and 30 but the seas were large and confused. It rained off an on. By midday the wind began to drop but the seas remained large preventing any work being done that day. By 2000 hrs we decided to proceed to the NE Peak of Georges Bank to begin the 36 hr station the following morning. The swell was still large by morning but we took net tows at St 7 to see if the Calanus populations were suitable for the study of diel periodicity in egg laying and diel changes in egg and naupliar abundance in the water column. Unfortunately Calanus abundance was very low and it was not a good location for the study. We then completed regular sampling at the station and then headed north back to the Gulf of Maine to complete the last station on the GOM transect. This was completed at night in some rather wild conditions with the wind blowing around 30 kts and large swells. Everything was completed, however, with no mishaps.

A large storm was predicted for Thursday with 40-45 kt winds on Georges bank. This would preclude us carrying out any time series study in the GOM or on GB before we had to leave on Friday to come in. We decided to head into sheltered waters in Massachusetts Bay to see if we could find sufficient animals to carry out the 36 hr study in sheltered waters while the storm was blowing. We stopped in the western Wilkinson Basin and collected Calanus for experiments and proceeded to a location just inside Stellwagen Bank in Massachusetts Bay. Unfortunately a net tow revealed very few Calanus and incredibly large numbers of phytoplankton which clogged even a 333 m net which precluded us from carrying out the 36 hr study at this location. The weather forecast at this point was predicting high wind and 22 ft seas for the following day in the S Gulf of Maine Georges Bank area. At this point we decided to return to Narragansett since we would not have been able to accomplish anything significant on Friday morning (if we were able to work at all), before having to break off to return to Narragansett on Sat.

Individual reports follow.

HYDROGRAPHY

CTD profiles for St 2-8 are shown in Figures 2-9. Adjacent to the Maine coast at St 2 (Fig. 2) water was mixed to the bottom (120m) with temperature about 3.7 and salinity 32.5. Chlorophyll fluorescence was low. Across the Gulf at Sts 3-6 the surface mixed layer extended down to about 60m and there was high chlorophyll fluorescence within this layer. Surface temperature was between 3.5 and 4.5 and salinity between 32.4 and 32.6. At St 8 adjacent to Georges Bank the mixed layer extended down to 100m, the temperature warmer than at other stations in the GOM (5.2 C), and chlorophyll fluorescence low (Fig 8). On Georges Bank (St 7) there were suggestions of a slightly colder fresher layer at the surface and then a well-mixed water column beneath this (Fig 9). Water temperature and salinity was higher than in the GOM (6 C and 33 respectively).

Figure 2. Station 2 CTD profiles

 

Figure 3. Station 3 CTD profiles

 

Figure 4. Station 4 CTD profiles

 

Figure 5. Station 5 CTD profiles

 

Figure 6. Station 6 CTD profiles

 

Figure 8. Station 8 CTD profiles

 

Figure 7. Station 7 CTD profiles

 

CHLOROPHYLL and NUTRIENTS

At each station size-fractionated chlorophyll a (<5m and Total) and nutrients (NH4, NO3, NO2, PO4) were measured at 10 m intervals down to 60 m and at the bottom. Values are shown in Table 02. At St 2 in Maine Coastal Water chlorophyll a was <1 g l-1 with most being in the <5 m fraction suggesting that the spring bloom had not yet begun. Nitrate and phosphate were high (>10 M and > 1.0 m) and the same throughout the 112 m water column. At St 3-6 across the Jordan and into the northern edge of Georges Basin total chlorophyll a was between 2 and 7 g L-1. Most of the phytoplankton was in the larger size-fraction. Nitrate and phosphate were lower than in Maine Coastal Water and decreased from towards the south (St 6) where nitrate was around 6 M and phosphate 0.7 M. These higher chlorophyll values coupled with lower nutrients, indicated that the spring bloom had already begun. This is very early for the central Gulf of Maine where typically high chlorophyll values are not seen until April and May (OReilly and Zetlin 1999). Perhaps it reflected the calmer weather experienced up until the time of the cruise.

Table 1. Chlorophyll a and nutrients from EN319.

 

 

 

 

 

 

 

Station

Depth, m

<5 m Chl a

>5 m Chl a

Total Chl a

DIP

NO3

 

 

ug L-1

ug L-1

ug L-1

uM

uM

1

0

0.58

1.17

1.75

 

 

1

5

0.50

1.01

1.51

 

 

1

10

0.67

0.92

1.59

 

 

1

20

0.53

1.26

1.79

 

 

1

30

0.54

1.13

1.67

 

 

1

40

0.63

1.12

1.75

 

 

1

44

0.49

0.94

1.43

 

 

 

 

 

 

 

 

 

2

0

0.40

0.20

0.60

1.10

11.04

2

5

0.40

0.40

0.80

1.07

10.82

2

10

0.40

0.10

0.50

1.07

10.61

2

20

0.38

0.29

0.67

1.08

10.72

2

30

0.40

0.14

0.54

1.13

10.73

2

40

0.30

0.06

0.37

1.08

10.93

2

60

0.27

0.33

0.60

 

 

2

112

 

 

 

1.12

10.93

 

 

 

 

 

 

 

3

0

0.75

2.06

2.81

0.99

8.66

3

5

0.80

2.16

2.96

0.96

8.70

3

10

0.95

1.86

2.81

0.94

8.45

3

20

0.80

2.11

2.91

0.96

8.64

3

30

0.90

1.61

2.51

0.95

8.77

3

40

0.85

1.76

2.61

0.95

8.61

3

60

0.05

0.15

0.20

0.94

8.58

3

168

 

 

 

1.35

13.86

 

 

 

 

 

 

 

4

0

0.66

1.97

2.63

0.93

8.19

4

5

0.73

1.74

2.47

0.90

8.20

4

10

0.73

1.55

2.28

0.90

8.19

4

20

0.70

1.82

2.51

0.90

8.23

4

30

0.66

1.58

2.24

1.00

8.46

4

40

0.31

0.73

1.04

1.24

8.86

4

50

0.02

0.01

0.04

1.11

9.69

4

239

 

 

 

1.55

18.99

 

 

 

 

 

 

 

5

0

0.66

2.32

2.98

0.83

7.06

5

10

0.58

2.43

3.01

0.84

7.01

5

20

0.77

2.09

2.86

0.81

7.12

5

30

0.70

2.43

3.13

0.84

7.27

5

40

0.71

4.18

4.89

0.82

7.05

5

60

0.70

2.40

3.09

0.84

7.32

5

157

 

 

 

1.39

16.83

 

 

 

 

 

 

 

6

0

0.62

2.28

2.90

0.75

6.25

6

10

0.77

2.47

3.25

0.72

6.09

6

20

0.70

2.16

2.86

0.74

6.22

6

30

0.62

6.34

6.95

0.73

6.27

6

40

0.77

2.05

2.82

0.72

6.27

6

60

0.85

2.32

3.17

0.79

7.18

6

199

 

 

 

1.39

19.81

 

 

 

 

 

 

 

8

0

0.62

1.35

1.97

0.90

8.96

8

10

0.73

0.89

1.62

0.90

8.78

8

20

0.77

1.08

1.85

0.92

8.70

8

30

0.77

1.24

2.01

0.90

8.99

8

40

0.93

1.24

2.16

0.91

8.98

8

60

0.66

1.12

1.78

0.93

8.93

8

226

 

 

 

1.47

18.40

 

 

 

 

 

 

 

7

0

0.58

1.28

1.85

0.80

10.05

7

10

0.35

1.12

1.47

0.80

7.66

7

20

0.35

1.12

1.47

0.81

7.93

7

30

0.46

1.39

1.85

0.81

7.93

7

40

0.39

1.51

1.89

0.82

7.95

7

66

0.62

1.08

1.70

0.76

8.03


 

ZOOPLANKTON ABUNDANCE

Below we present zooplankton pump counts. At this stage the MOCNESS samples have not been enumerated.

Plankton Pump Counts. Zooplankton pump samples were collected and counted using standard GLOBEC Broadscale Survey Procedures. Samples were normally collected from 100-70m, 70-40m, 40-15m and 15-0m. Table 2 shows the abundance of Calanus finmarchicus stages for the different depths, while Table 3 shows the total abundance of Calanus over the whole water column at each station. At all stations there was a population of young nauplii and copepodites. Abundance of nauplii was lowest at St 8, adjacent to Georges Bank (8,700 m-2); elsewhere across the Gulf numbers were between 23,000 (St 2) and 55,000 m-2 (St 5). On Georges Bank (St 7) abundance of Calanus nauplii was higher (76,000 m-2), but there were relatively fewer older stages present compared with St 2-6 in the Gulf of Maine.

Other abundant copepod nauplii included Oithona, Calasocalanus/Paracalanus, Metridia and Pseudocalanus (Table 5). Oithona was particularly abundant with total numbers >1,000,000 m-2 at all stations but St 2 and 4. Microsetella was quite abundant but was present mostly as copepoidites at depth.

Table 2. Abundance of Calanus finmarchicus nauplii copepodites and adults within each depth range from plankton pump samples. Numbers are the number per square meter for each pump depth range.

ST

TOW

NET

DEPTH

N1

N2

N3

N4

N5

N6

C1

C2

C3

C4

C5

FEM

MAL

2

1

4

15-0

0

398

1820

1820

3355

1535

512

114

284

114

171

455

0

2

1

3

40-15

0

702

3367

2666

3227

1122

281

281

0

0

0

140

0

2

1

2

70-40

0

775

339

0

97

97

145

48

0

48

0

0

0

2

1

1

100-70

121

483

241

0

121

1328

121

0

0

0

0

241

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

2

4

15-0

0

3808

2240

1344

1792

0

448

672

448

0

0

0

3

2

3

40-15

0

606

4040

2424

2222

808

202

404

808

202

0

202

202

3

2

2

70-40

0

0

4144

0

2486

4972

0

829

829

829

0

0

0

3

2

1

100-70

0

253

0

253

505

253

0

0

0

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

3

3

15-0

66

1052

3089

1577

2300

1709

657

460

460

131

0

66

0

4

3

2

70-15

0

2987

7767

1195

2390

2390

2987

1195

4182

0

0

597

0

4

3

1

100-70

0

0

342

0

0

0

0

0

0

85

0

0

85

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5

4

4

15-0

239

1196

8371

3348

3348

1674

1435

718

1435

0

0

0

0

5

4

3

40-15

1853

1853

6949

3706

3706

4633

3706

463

1853

463

0

463

0

5

4

2

70-40

1099

4395

4212

1465

549

732

2014

549

366

0

0

0

549

5

4

1

100-70

0

119

119

0

0

119

0

0

0

119

0

119

119

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

5

4

15-0

647

3019

6686

2372

5608

2804

2157

863

3235

2588

216

216

0

6

5

3

40-15

544

6527

5439

2719

0

2176

3807

544

1632

0

0

0

0

6

5

2

70-40

342

2052

2394

0

0

0

1710

342

0

0

0

0

0

6

5

1

100-70

0

128

0

64

0

0

0

0

0

64

64

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

6

3

15-0

247

2721

16822

4948

1484

1237

990

247

742

247

0

0

247

7

6

2

40-15

0

7357

16350

2997

272

1635

817

545

0

545

0

0

272

7

6

1

70-40

895

8053

6860

1193

1790

1193

1491

895

597

0

0

0

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8

7

4

15-0

0

204

409

818

204

613

818

0

409

613

0

0

0

8

7

3

40-15

0

0

1738

579

290

290

290

434

0

145

0

145

0

8

7

2

70-40

0

933

466

466

933

0

0

466

466

466

0

0

466

8

7

1

90-70

0

501

250

0

0

0

0

0

0

0

0

0

0

 


Table 3. Total water column abundance of Calanus finmarchicus nauplii copepodites and adults from plankton pump samples. Samples were collected between 0-100m or 0 and the bottom, if it was less than 100m.

ST

TOW

N1

N2

N3

N4

N5

N6

C1

C2

C3

C4

C5

C6F

C6M

Tot Naup

Tot Copeps

Tot Adults

M2Tot Cop

2

1

121

2,357

5,767

4,486

6,800

4,083

1,058

443

284

162

171

837

0

23,613

2,118

837

26,568

3

2

0

859

11,992

4,917

6,558

7,825

202

1,681

2,309

1,479

0

202

202

32,151

5,670

404

38,225

4

3

66

4,039

11,198

2,772

4,690

4,099

3,645

1,655

4,642

217

0

663

85

26,864

10,159

749

37,772

5

4

3,191

7,563

19,651

8,519

7,604

7,158

7,155

1,730

3,654

582

0

582

668

53,686

13,122

1,251

68,059

6

5

1,533

11,726

14,519

5,156

5,608

4,979

7,674

1,749

4,867

2,652

280

216

0

43,522

17,221

216

60,959

7

6

1,142

18,131

40,032

9,138

3,546

4,065

3,298

1,687

1,339

792

0

0

520

76,055

7,116

520

83,691

8

7

0

1,638

2,864

1,864

1,427

903

1,107

901

875

1,225

0

145

466

8,695

4,108

611

13,415

 

Table 4. Total water column abundance of zooplankton taxa from plankton pump samples. Samples were collected between 0-100m or 0 and the bottom, if it was less than 100m.



EGG PRODUCTION STUDIES Feb-Mar. 1999

J. Runge, B. Niehoff, P. Joly

Egg production rates of Calanus finmarchicus and Pseudocalanus spp. and hatching success of Calanus were measured along the Gulf of Maine transect. To measure egg production rates, females from vertical live tows were sorted immediately after capture. At each station 40 female Calanus finmarchicus were placed individually in petri dishes (30ml). At 8h intervalls, eggs were counted and removed from the incubation vials. Pseudocalanus spp. females were kept in groups of 5 in scintillation vials (45ml) containing either filtrated seawater or a feeding mixture containing Skeletonema costatum and Nannochloropsis sp. After 24 hours, the females were preserved for later analysis of egg sac number and size. Part of the live tows for the egg production measurements was preserved in formaldehyde and glutaraldehyde for studies of gonad development, including determination of the reproductive index and staging of gonad development. Hatching success of Calanus eggs produced during incubations was measured by incubation of batches of 50 randomly selected eggs for a 72 h period at 5-7 C.

Egg production rates of C. finmarchicus varied between 15 and 62 eggs female-1 d-1 (Table 01). Clutch size ranged between 39 and 53 eggs. Hatching success varied between 63 and 92%, indicating maternal nutritional conditions were not a significant factor in determining egg survival. The lowest egg production rates were observed at the most nearshore Gulf of Maine station. Egg production rates at deeper stations in the central Gulf were relatively constant at 45-53 eggs female-1 d-1. The Pseudocalanus incubations were preserved for later analysis.

 

Table 5. Summary of egg production data for Calanus finmarchicus. EPR denotes egg production rate (eggs female-1 d-1) and clutch size is mean eggs female-1. Standard error in parentheses (n= 36-40). Hatch success represent percentage of eggs hatching to nauplii Standard error (n=5) in parentheses. No data for GOM-2 and GOM-9.

Date

 

Station

Time

EPR

Clutch Size

Hatch success (%)

23 Feb.

GB-01

1400

34 (3.3)

40 (3.0)

92

27 Feb.

GOM-2

1310

15 (3.4)

39 (3.5)

-

27 Feb.

GOM-3

2020

62 (7.3)

53 (2.6)

63 (7.4)

28 Feb.

GOM-4

0920

57 (5.3)

48 (2.3)

79 (3.2)

28 Feb.

GOM-5

1410

40 (5.2)

49 (3.0)

79 (2.0)

28 Feb.

GOM-6

2000

53 (5.6)

49 (2.4)

80 (2.2)

02 Mar.

GOM-7

1115

56 (6.2)

45 (2.9)

86 (2.5)

02 Mar.

GOM-8

2130

34 (3.9)

36.(2.7)

72 (1.6)

03 Mar.

GOM-9

1035

55 (6.1)

46 (3.1)

-

 

EN319 List of Personnel

Name

Title

Organization

 

 

 

Dr. Edward Durbin

Chief Scientist

GSO, URI, Narragansett, RI

Dr. Jeffrey A. Runge

Scientist

Institut Marice Lamontagne, Quebec

Dr. Robert G Campbell

Marine Scientist

GSO, URI, Narragansett, RI

Ms Maria Casas

Research Associate

GSO, URI, Narragansett, RI

Ms Melissa Wagner

Graduate Student

GSO, URI, Narragansett, RI

Dr Barbara Niehoff

Post Doc.

WHOI, Woods Hole, MA

Pierre Joly

Technician

Institut Marice Lamontagne, Quebec

Isabelle Berube

Technician

Institut Marice Lamontagne, Quebec

Ms Guylaine Morrier

Graduate Student

UQAR, Rimouski, Quebec

Ms Sandrin Guittard

Graduate Student

UQAR, Rimouski, Quebec

Mr David Field

Graduate Student

Scripps Inst Oceanogr., UCSD, CA

Mr Sean Smith

Student

Univ. New England, Biddeford, ME

EVENT LOG EN319