SENTER FOR MARINT MITJØ

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1 SHIP: F/F G.O. SARS SENTER FOR MARINT MITJØ HA VFORSKNINGSINSTITUTIET INTERN TOK1RAPPORT DEPARTURE: Bergen January 3rd, 1700 GMT. ARRIV AL: Bergen January 19th, 0420 GMT AREA: NORWEGIAN TRENCH, CONTINENTAL SHELF OFF MØRE AND ADJACENT FJORDS, EAS1ERN PART OF THE NORWEGIAN SEA. PURPOSE: Study the horizonta and vertica dynamics of the overwintering zoopankton community and the bioogica activity with respect to respiration and excretion. Compare baseine vaues of nutrients, chorophy and fuorescence in different water masses (Fjord water, Coasta water, Norwegian Trench water and Norwegian Sea water). PERSONELL: Berit Endresen, Berit Hofstad, Kirsten Arnesen ( ), Juio Erices ( ), Magnus Johannessen, Jens Nejstgaard, Tom Noji and Tor Knutsen. INSTRUMENT PERSONELL: Martin Dah, Egi Øvretveit. AREA OF INVESTIGATION The primary area of investigation is the continenta shef off Møre where the main spåwning grounds for Norwegian spring-spawning herring are ocated. Figure a & b shows the surveyed area. Due to the ocaisation of the main study site other areas of interest are the upstream areas of the Norwegian Coasta Current and Trench areas off the west coast of Norway. In these southern areas primary and secondary production might be initiated earier than at the Møre shef. Thus the northward transport of the Norwegian Coasta Current probaby infuence the Møre shef by advective production. Another important area is the deep water off the shef in the Norwegian Sea, where overwintering copepods inhabit the deep waters migrating to

2 the surface waters in eary spring to feed and reproduce. This area is aso important with respect to arge popuations of euphausiids which inhabit the sope and deep waters of the Norwegian Continenta Shef. The fjords at Møre are important reference areas with respect to their zoopankton stocks and the onset of the phytopankton boom. Eary stratification of the water coumn in the fjords due to freshwater input, might be a key facor in initiating the primary and secondary production here. The seaward transport of surface waters containing stocks of phytopankton and zoopankton, might significanty infuence the shef waters and shaow archipeago outside the fjords, where the first spawning of herring takes pace. 2 Samping MATERIALS AND METHODS Mesozoopankton were samped by a new piece of equipment caed MULTINET borrowed from the University of Kie. It was run on a portabe CTD winch with 1500 m of cabe. The 0.25 m2 MULTINET is equipped with 5 nets of 180J.1m mesh size and is especiay designed for mutipe vertica haws. Macrozoopankton (and mesozoopankton) were samped between m by a 1m2 MOCNESS equipped with 8 nets of 180 Jm mesh size. Sampes were stratified according to possibe zoopankton registrations observed with the EK500 echo sounder (38 and 120 khz). On each station echo integration was performed for the same depth interva as samped with the MOCNESS and MULTINET. A HARSTADTRA WL and IKMT (Isaac-Kidd Midwater Traw) was used to sampe and identify scatterers observed by the EK500 echo sounder at 38 and 120 khz. The Harstad traw is a peagic traw with an opening of 16 x 16 fathoms. On the cod-end side it is ined with a 4-5 m inner net with a 5 mm stretched mesh size. The. IKMT is a smaer peagic traw with a ength of 13.3 m and a mouth area of 4 x 3 m. It has a mesh size that changes from 25 mm cose to the mouth of the net, to 5 mm in the ast 4 m c ose to the c od -end. An inn er net of mesh size 1.15 mm and a ength of 1.75 m is mounted in front of the cod-end. Live copepods and kri for metaboism, gut fuorescence and defecation experiments were coected at some stations as described beow. At certain ocaities feca peets were samped with 30 Niskin water bottes at seected depths and coected on a 30 Jm net.

3 L JAN 1992 z CTD St. nr 1-20 "G. O. SARS" Figure. Surve y area. a) CTD stations. b) Bioogica samping.

4 b) JAN 1992 TRAWLSt.nr 1-6, M MOC.St.nr1-33,<>PLANKTON St. "G.O.SARS" Figure continued.

5 5 Experiments The metaboic activities of copepods and kri were measured by shipboard incubation experiments at six seected stations (Tabe 1). Water for the incubation experiments was coected with 30 Niskin water bottes. Surface water was usuay taken between m, whie deep-water was samped within some distance from the bottom, depending on the maximum depth at the stations (Tabe 1). The samped water was fitered through GFF fiters, thoroughy mixed in 25 poycarbonate bottes and cooed to in situ temperature. Live animas for the experiments were coected at seected depths during night (Tab e ). Kri were caught in surface waters by short (20 min) haus with an IKMT equipped with a non-fitering cod-end. Copepods were coected at seected depths using a 0.8 m2 net (mesh size 375 J!m) with a Nansen cosing system and a 16 water tight codend. Care was taken to minimize disturbance to the animas and incusion of damaged specimens in the experiments. The copepod net was retrieved at ow speed ( ms-). Upon arriva at the surface the contents of the water tight codends were immediatey diuted in 40 containers with in situ tempered surface water and sorted by eye into the incubation bottes under ow ight conditions. Seemingy undamaged copepods were pipetted into sma monospecific batches of approx individuas. The batches of copepods (5-8 m) were rinsed by adding fitered tempered sea-water (35-40 m) and subsequenty adjusting the voume to 5 m by reversed fitration. The rinsed batches of copepods were then immediatey transferred to airtight 250 m gass bottes containing pre-tempered fitered sea-water, and incubated in darkness for 10 to 29 h (see Tabe 1). Kri were sorted from the sampe by catching 1-5 specimens in a speciay constructed sma coarse-net sieve (1.4 mm mesh). After removing other animas and rinsing with fitered sea-water, the kri were transferred to air-tight gass bottes, and incubated as described for the copepods. For each series of incubations 3-5 additiona bottes were used as banks. Banks were treated as the incubation bottes, except that the batches of rinsed water added at the start of the incubations contained no animas. In the copepod experiments stage CV copepodites and femaes of Caanus finmarchicus (Gunnerus) were normay seected for the experiments. However, in some cases sufficient amounts of C. finmarchicus coud not be found, and and. other dominating species were incuded; as Metridia onga ( Lubbock) (experiment #3,#5 and #6), and Peuromamma robusta (Dah) (experiment #6).

6 In most of the kri experiments M eganyctiphanes norvegica (M. Sars) was incubated. An exception was experiment #3 for which animas were caught in the Onadeep. At this ocaity Thysanoessa inermis (Krøyer) was the dominating species, and was therefore used in the experiments. Ta be. Respiration and excretion experiments. Norwegian Trench 60 59',03 42' Geographica Date Sampe depth Tota# Incub. position Water Animas animas time(h) Copepods No experiment performed Kri 30m 12 O 2 Storfjord 62 23',06 18' Copepods (Surface) Om m (Deep) 300m m Kri 10m Om Onadeep 63 04',05 50' Copepods 10 m m Kri Om m Modefjord 62 41',07 02' Copepods (Surface) 50 m m (Deep) 400m m Kri 10m 20-0m Norwegian Trench 60 59',03 40' Copepods 20m m Kri 20m m Norwegian Sea 63 14',04 09' Copepods 75 m m Kri No experiment performed 6 At the end of the incubations the activity of the animas were checked before samping, and a few cases of mortaity were noted. Dupicate sampes for oxygen, ammonium and phosphate were taken from each botte, except from the copepod fasks where ony one oxygen sampe coud be taken due to the smaer incubation botte voume. In addition to the experiments on metaboic activity two gut defecation experiments on C. finmarchicus and M. onga were conducted on January 12th and 13th in Modefjorden and Storfjorden respectivey. Both experiments were conducted during the night. In the first experiment we compare in situ gut fuorescence and microscopica determined gut content, in freshy coected

7 copepods from deep ( m), respective surface waters (100-0 m). In the second experiment we simutaneousy anayze the in situ feca peet production and the microscopicay determined gut evacuation in copepods from surface waters (100-0 m) during a times series. Freshy coected animas were incubated in in situ tempered GFF-fitered sea-water for intervas ranging from 15 minutes to 6 hours. Studies of vertica migration On the main ocaities, where the experiments where performed, diurna studies of vertica migration within the pankton community were aso undertaken. The main gear used was MOCNESS which was run approximatey every 4th hour. Other types of gear ike MULTINET, IKMT and Harstad traw was run when possibe. At these ocaities water sampes for anayzing siicate, phosphate, nitrate, nitrite, phosphate, ammonia, particuate organic carbon (POC), particuate organic nitrogen (PON), particuate organic phosphate (POP) and oxygen were taken. Phosphate and ammonia were anayzed manuay on board the vesse and oxygen was measured by a modified Winker method. On seected ocaities kri and copepods were samped for genetic studies and stored at -90 C. Caibration The MOCNESS fow meter #2 was caibrated during the cruise on two occasions in Storfjord using GPS positioning above ground as a reference of saied distance. The resuts show a caibration factor of 4. 7 and 4.25 respectivey, given a combined factor 4.5 which has been used as the caibration factor for MOCNESS tows during the cruise. The MOCNESS depth sensor was tested against the SCANMAR depth sensor in the upper 00 m. No significant differences between the depth recorded by the two sensors were found. Temperature and sainity RESULTS- FIELD STUDIES Temperature and sainity at the four major sites of investigation are representative of the winter situation to be found in these specific marine regimes. Athough these are first resuts and are iabe to modification during further data processing, some patterns can be estabished. 7

8 At Station 3 ocated in the Norwegian Trench off Sognefjorden, temperature and sainity (Fig. 2 a & b) ranged from about 7 to 9 C and 35.0 to 35.3 o/oo, respectivey. The watermasses observed at this station seems to be of true Atantic origin. The we-mixed water from the surface down to a depth of OOm is probaby a res ut of intense mixing and winter cooing but might aso be sighty infuenced by ne ar coasta and North Sea water. 8 Sta 3 - Tempe ratu re r C) Sta 3 - Sainity (%o) o o \ \. m m V a) b) ' = j Figure 2. a) Temperature and b) sainity profies for Station3. A transition zone from a we-mixed surface ayer to a warmer and more saine water type occurred between the depths of 00 and 200 m. The peak vaues of temperature and sainity at about 200m depth indicate a major infow of Atantic Water to the Norwegian Trench.

9 Beow a depth of about 270 m temperature decreased, indicating that the deep water of the Trench was ess infuenced by the major Atantic infow. In contrast, at Station 4 in Storfjorden, the vertica distribution of temperature and sainity (Fig. 3 a & b) was ess ocean i c in character. Lowest sainities were found at the surface as a resut of freshwater runoff into the fjord. Vaues increased with depth as a re sut of mixing with higher-sainity waters at the bottom of the fjord. Sainities above 35 o/oo were measured beow about 250 to 300 m depth, which indicated the presence of Atantic Sta 4 - Tempe ratu re r C) Sta 4 - Sainity (%o) o o r J \_ ') V m m " \: 9 ' \ \ \ a) b) Figure 3. a) Temperature and b) sainity profies for Station4.

10 water at these depths. The ower temperatures in the surface waters are probaby a resut of winter cooing near the surface and the input of coder freshwater. In the upper 100m the variabe temperature indicates the presence of severa ayers and a compex current regime. Temperature increased to a depth of about 100 m probabe due to mixing with the deep water. Beow 100 m vaues again decreased to a depth of 300 m, where they stabiized with the presence of Atantic Water. The situation at Station 6 on the shef at Møre (Fig. 4 a & b) presents yet another scenario. Reativey warm, ow-sainity coasta current water formed a distinct ayer from the surface to about 20 m, and beow 160 m the warmer water with higher sainity appeared to be of Atantic origin. Between these two depths was a zone of gradua transition. 1 o

11 o Sta 6 - Tempe ratu re r C) Sta 6 - Sainity (%o) o ) \ ' i m 100 m \. 140 \ 1\ a) \ \ b) \ Figure 4. a) Temperature and b) sainity profies for Station6.

12 Sta ti on 8 in Romsdasfjorden (Fig 5 a & b) was simiar to that in Storfjorden with respect to the genera pattern of temperature and sainity with reativey cod ess saine water near the surface and more oceanic conditions at depth. Distinct cooing of surface water and therma discontinuities were indicated in the upper 100 m of the temperature profie. 50 Sta 8 - Tempe ratu re r (.) 12 Sta 8 - Sainity (%o) o o L ( \ t : J m 250 m '..... '-.. \ \ \, a) 500 b) # Figure 5. a) Temperature and b) sainity profi es for Station8.

13 The Norwegian Sea station (Station 16) was characterized by typica oceanic temperature and sainity profies (Fig. 6 a & b). Reativey warm, high-sainity Atantic Water extended from the surface down to severa hundred meters depth, and cod, owersainity Norwegian Sea Deep Water prevaied at greatest depths. In addition, a transition zone of ntermediate Water was recorded between m. A genera observation was that the surface temperatures of the fjord and shef stations seem to be quite high compared to the ong term mean vaues for this part of the Norwegian coast. Sta 16- Temperature rc) Sta Sainity (%o) -1 o s o o - _, 13 -r TT m 600 ( j V i""" m ! _, a) 1200 Figure 6. a) Temperature and b) sainity profies for Station16. b)

14 14 Phosphate and ammonium Preiminary findings for phosphate and ammonium were aso typica of the winter situation winter in these regions. Phosphate concentrations were high reative to vaues in ate spring and summer, at which times phosphate may be am ost depeted in surface waters by intensive uptake by phytopankton. Fa/winter mixing renews these depeted surface waters with phosphate. Ammonium, in contrast, was present in ow concentrations reative to conditions in spring and summer. As ammonium is argey suppied by excretion from zoopankton and higher trophic forms, the former which is at an annua! mtntmum in terms of biomass and activity, winter concentrations are typicay ow. An exampe of the vertica distribution of phosphate and ammonium is presented in Fig. 7 a & b. The findings are from the station between Langgrunnsbanken and Buagrunn at Møre (Station 6). Sta 6- Phosphate Sta 6- Ammonium a) pmp b) o pmnh4 Figure 7. a) Phosphate and b) ammonium profi es for Station6. It is noted that the high phosphate vaue at 190 m at Station 6 may refect nutrient remineraization from the sediments at about 200 m. The reativey high surface vaue for ammonium may be due to excretion by swarms of kri observed at the surface of this station.

15 Fuorescence The very ow vaues of the continua vertica profies of fuorescence (Fig. 8 a-e) at a stations refect the typicay ow concentrations of suspended chorophy, i.e. phytopankton, in winter aong the Norwegian coast and in the fjords. Generay fuorescence decreased sighty with depth. At Sta ti on 3 in the Norwegian Trench there was a distinct peak at about 20 m as we as an increase in vaues at depth (Fig. 8a). The atter may be due to resuspension of materia from the sediments or from hyperbenthic nepheoid ayers Sta 3 - Fu o rescence (V) Sta 4 - Fu o rescence (V) o m m b) Figure 8. a) Fuorescence Station 3, b) fuorescence Station 4, c) fuorescence Station 6, d) furescence Station 8 and e) fuorescence Sta ti on 16.

16 The stations at Storfjorden (Station 4, Fig. Sb) and Romsdasfjorden (Station 8, Fig. Sd) each exhibited distincty higher vaues for fuorescence near the surface reative to ower depths. A singe peak near the surface was evident at the Møre station (Station 6, Fig. Se). Sta 6 - Fua rescence (V) Sta 8 - Fuorescence M o.. j_ 20 r m j 1 t i.j. ( > t c) d) Figure S continued.

17 Fuorescence at the Norwegian Sea station (Station 16, Fig. Se) was ow throughout the water coumn. These vaues were the owest of a stations during this cruise and presumaby refected the extremey ow concentrations of chorophy in these waters. 17 Sta 16- Fuorescence M r e) Figure 8 continued..

18 18 RE SUL TS - EXPERIMENT A TJON Resuts from the experiments on metaboic activity are presented in Tabe 2. It shoud be noted, however, that these vaues are ony preiminary and expressed as oxygen consumption per individua (J * individ- * h-1 ). These cacuations wi ater be corrected for average body weight. Tabe 2. Preiminary resuts of metaboic activity for kri and copepods. Experiment Samp. depth (m) Para. ncubation time (#) (h,min) ave rage #nd. per botte ave rage Oxygen consumption (*ind.-1 *h-1) ave rage min max Møganyctphanes norvegca Kri 1 30 Kri 2 Kri 4 Kri ,35 26,15 13,56 13,53 2,2 4,8 4,0 5,8 63,26 16,39 57,03 16,28 38,81 7,54 47,30 7,69 112,43 20,91 67,47 28,55 Thyssanossa nørms Kri ,05 4,4 19,96 17,06 22,99 Ca/anus fnmarch/cus Cop. 1 surface deep Cop Cop. 3 surface deep Cop ,16 27,08 18,23 14,54 13,02 12,21 23,0 41,8 30,0 22,0 32,2 13,0 o, 158 0,058 o, 102 0,093 o, 130 o, 115 0,202 no paraes 0,081 0,044 0,065 no paraes 0,261 0,119 o, 145 o, 117 Møtrd/a onga Cop. 2 Cop.4 Cop ,31 12,24 12,16 23,0 37,2 23,0 0,096 0,074 o, 189 0,051 0,002 0,184 0,142 0,137 o, 194 Pøuromamma robusta Cop ,17 21,o 0,282 0,250 0,315

19 ASSESSMENT OF EQUIPMENT AND RECOMMENDATIONS The foowing is a brief assessment of the performance of equipment used during this cruise. Recommendations for future cruises are presented.. Winches, boom and cabe A. Inadequacies of the present winch system The present array of winches and cabe is inadequate to propery sampe pankton at depths beow about 600 m, e.g. in deep fjords and open-ocean regions of the Norwegian and Greenand Seas. Presenty the depth of depoyment of the MOCNESS is imited by the ength of the wire used to carry the oad of depoyment. Further, the necessity to connect an additiona coaxia cabe to the MOCNESS to transmit signas makes the procedure unduy compicated. This cabe is iabe to entangement with the net and/or the carrying wire which can resut in damage during depoyment as we as on deck. Especiay the operation of the traw doors and sharp edges of the ships hu was damaging the cabe. It was necessary to repair this cabe severa times during the cruise, whereby the cabe was shortened by about 250 m. More over, with the introduction of the Mutinet to routine samping, it was necessary to insta a sma, portabe CTD winch equipped with approximatey 1500m of coaxia cabe. Notaby, the winch does not have the capacity to carry the MOCNESS. As the same boom must be used to depoy the MOCNESS, Mutinet (and Isaac-Kidd, etc.), it is consideraby inconvenient, very sow and probaby damaging to the cabes and connectors to change from one piece of equipment to another. This is especiay true as the "strekkavaster" on the cabes must be mounted and removed during each change. This is a major probem. As we fee that it is of primary importance to be abe to sampe the deep ocean, to do this efficienty and to protect the cabes as we as possibe, we strongy recommend the purchase of a arge winch outfitted with at east 3500 m of cabe to accommodate the MOCNESS, Mutinet and possibe other pieces of equipment requiring teemetric communication with shipboard units. B. Performance -- Performance of the winches was generay satisfactory, athough the y are not design ed for the depoyment of our equipment at depths of greater than about 400 m (see point ) However, especiay but not on y under p o or weather 1 9

20 conditions, the foowing probems were encountered: - The boom used in running the MOCNESS and Isaac-Kidd traw apparenty cannot withstand the added tension caused by a rocking ship. This probem prevented the depoyment of these two pieces of equipment on severa occasions. - The "sipring" on the winch u sed for the MOCNESS wire as we as the "sipring" on the winch for the traw-sonde-cabe did not operate 100 %. The atter winch was repaired. It is noted that the housing for the "sipring" on this winch is not equipped with a heater to prevent oxidation of parts due to moisture. The "sipring" on the other winch was not repaired during the cruise. 2) The Isaac-Kidd-Traw pro ved to be a good surface samping de vice for kri which were to be u sed in experimentation. However, as it cannot be cosed during depoyment, we coud not use it to sampe discrete subsurface ayers of pankton. We suggest us ing the MOCNESS fitted with one (or more) net of coarse mesh ( 000 Jm) for samping subsurface ayers of kri. In addition, a arge cosed cod-end shoud be constructed for coection of "ive sampes". 3) The arge ring net (fitted with a arge cod-end) used for coecting copepods for experimentation was a good device in cairn weather. With strong winds and currents, however, it was difficut or impossibe to use. Moreover, estimating the actua depth of the net was occasionay difficut. Use of additiona weight (a tota of ca. 30 to 40 kg) beow the net and mounting a Scanmar pinger for detecting depth may resove this probem. 2. Laboratory faciities 20 The aboratory faciities on board F/F G.O. Sars are in genera satisfactory. However, with the increasing interest in performing shipboard experiments with ive zoopankton and/or phytopankton, we fee that a temperature and ight reguated room or sma aboratory is worth considering. Permanent storage of formain in one of the aboratories shoud not be permitted, as this chemica is damaging both to peope and the ive animas treated on board the ship. Both the heat cabinet and fridge in one of the aboratories shoud be repaced as they did not function. Thomas Noji Jens Nejstgaard Tor Knutsen