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The Northern Ocean

Salinity andTemperature




Hydrographic-biological studies of
the North Atlantic Ocean and ...

Haakon Hasberg Gran



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W. a. FARI.OW.




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Report OP Norwegian Fishery- and Marme-lDYestigations Yol. I 1900 No. 6.



HTDR06RAPHIC-BI0L06IGAL STUDIES



OF

THE NORTH ATLANTIC OCEAN



AND



THE COAST OF NORDLAND



BY
M. H. GRAN

WITH 2 PLATES



•^^1-^



KRISTIANIA

OSCAR ANDERSENS BOGTRYKKERI

1900



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n



y-^eln



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Table of Contents

Page

Introduction 1

I. The North Atlantic Ocean.

1. Hydrographic investigations 3

2. Plankton investigations in 1898 10

II. The Coast-waters of Nordland.

1. Hydrographic investigations 14

2. Plankton studies

Introduction 25

Biogeographical survey of the most important species 29

Chlorophyce«e 29

PlageUata 30

Bacillariales 30

Peridiniales • 41

Protozoa 48

Copepoda 50

Other animals 54

Plankton communities 56

A. Neritic communities 57

B. Oceanic communities 61

Quantitative plankton investigations 67

The annual periods of the coast plankton 71

General view of the distribution of the plankton in the summer and autunm 73

H. Connection between hydrographic and biological conditions 86

Bibliography • 91

Hydrographic Tables

Remarks on the Hydrographic Tables II

1. North Atlantic Ocean; 1897—98.

1. Norway to Iceland: March, 1897 VII

2. Utsire to Jan Mayen; March 1898 : . . . VIII

3. Norway to Iceland; March, 1898 IX

4. Bergen to Arctic Ocean; May, 1898 XI

5. Arctic Ocean to Aalesund: May, 1898 XII

6 Tromse to Arctic Ocean; April, May, 1898, S.8. Hvidflsken XIV



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7. Tromse to Arctic Ocean; April to June, 1898, S.S. Jasai XV

a Arctic Ocean; Summer of 1898, S S. Hvidflsken XVI

9. Arctic Ocean to Tromse; September, 1898, Hvidflsken XVII

10. Arctic Ocean: Summer of 1898, Jasai XVII

11. Spitzbergen to Tromse; September, 1898, Jasai XVII

12. Iceland to North Sea: July, 1897 XVIII

13. Iceland to Norway; July, 1898 XIX

14. Iceland to Leith; September, 1898 XX

II. Observations off the Coast of Nordland I898.

A. Observations in the West Fiord.

a. Square and longitudinal section of the Fiord, 15— 27th July .... XXV

b. Square section of the West Fiord, 3rd August XXVI

c. Square section of the Fiord, 8th September XXVI

d. Ofoten and Tys Fiord XXVII

e. Near Bode ' XXVlll

B. Bids Fiord.

a. Section of the Bids Fiord, 29th, 30th July XXX

b. Section otf the Fiord, 22rd, 23rd September , . . . . XXX

III. Sections off tlie Eids Fiord. Nordland, 1899.

a. Section off the Bids Fiord, 4th, 5th July XXXV

b. Bids Fiord, 19th July XXXVl

c. Section off the Eids Fiord, 24th, 25th July XXXVl

d. Bids Fiord 9th -14th August XXXVII

e. Section off the Eids Fiord, 26th, 28th August XXXVl II

Plankton Tables.

Remarks on the Plankton Tables

I Bergen to Arctic Ocean; May, 1898

II Arctic Ocean; April— June, 1898

III West Fiord, Ofoten Fiord, Tys Fiord, 1898

IV Plankton from Bode, 1898

V Eids Fiord, July- September, 1898

VI Investigations in the Fiords of Tromse and Finmarken. 1898
VU Eids Fiord, 1st ~ 5th July, 1899

VDI Bids Fiord, 17th— 25th July, 1899

IX Ofoten Fiord, 28th July, 1899

X Eids Fiord, August— October, 1899

XI Here, 1898, (L. Johansen)

XII Surface-Plankton from Here, 1899, (L. Johansen)

XIII Plankton from Rest in Lofoten, 1898—99 (J. Nilsen)



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Introduction.

In this paper the results will be recorded of the hydrographical observa-
tions in the North Atlantic Ocean, which were made in 1898 at the
instigation of the Norwegian fisheries investigations, under the direction
of Dr. Johan Hjort,

They are principally observations of the temperature and salinity of
the surface at different periods of the year; the material has been pro-
cured through the kind assistance of captains of private steamers, as will
be seen from the following pages, where the name of the observer is
always given. Moreover a series of deep-sea observations has been made
by Captain Bie, assistant in the investigation, on H. M. S. Heimdal, with
which, through the kindness of the Admiralty, he was allowed to accom-
pany the expedition.

During the last two summers, the present author has examined the
hydrographic and biological conditions of the sea and the fiords along the
Nordland coast, with the special object of obtaining a general view 01
the hydrographic conditions at that season of the year, when the arrival
of the summer herring takes place.

Plankton series have been procured for all seasons of the year, by
the kind assistance of private individuals, from Hero in Helgeland and
from Rost.

The first section treats of the obser\^ations taken on steamer routes
across the North Atlantic; the second section gives an account of the
investigations on the coast of Nordland.

On behalf of the direction of the investigations, I beg to thank the
private and public individuals and institutions, that have contributed by
their kindness towards the promotion of this work.



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I. The North flflanfic Ocean.

I. Hydrographic Investigations.

Upon the basis of O. Pettersson's and Cleve's epoch-making researches,
a whole literature has of late years come into existence on the
subject of the hydrographic and biological conditions of the Norwegian
North Atlantic.

One of the most important problems still awaiting its solution, is
the relation between the east Icelandic polar current on the one hand,
and the Gulf Stream on the other.

It is well known that O. Pettersson has advanced the hypothesis
that in the winter the polar current increases so greatly in extent, that
in certain years, at any rate, it breaks through the Gulf Stream, and
pours its volumes of water into the North Sea and the Skagerrak. It
^as the annual hydrographic changes in the Skagerrak, that suggested
this idea to Pettersson, and he was confirmed in his view by the fact that
Cleve [96, 97]* and Aurivillius [96, 98] found arctic plankton organisms
on the shores of the Skagerrak in the winter.

The object was thus to investigate the conditions out in the North
Atlantic itself during the winter. No other investigations had as yet been
made of that region except the taking of surface-temperatures, which
Mohn [87] through a series of years had collected with the assistance of
Norwegian sealers and whalers. By means of these observations, Mohn
was enabled to construct the chart of the mean temperature of the sur-
face of the sea in the month of March, which he published in his valuable

•) The Bibliography is referred to by numbers indicating the year of publication
of the treatise placed between brackets [ ] after the name of the author.



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treatise in tiie Report of the Norwegian North Atlantic Expedition (1. c.
PL XXVIII).

The first investigations of the salinity in the North Atlantic in the
winter, were carried out under the direction of Dr. Johan Hjort. Through
the kind assistance of Norwegian sealers, he was enabled to procure
material for a hydrographic map of the surface of the North Atlantic
in March, 1897, which was published in a preliminar}^ account in cNaturem
{Hjort [97)), and later in a longer treatise by Hjort & Gran [99].

This map showed that 0. Petterssons theory was correct in so
far as the polar current in winter is much greater in volume and extent,
than had previously been supposed; and that the Gulf Stream was much
less powerful than it is known to be in the summer.

On the other hand, it appeared that the Gulf Stream, even in
March, was powerful enough to form a barrier from the Faroe Isles and
the Shetland Isles, past the northern pan of the North Sea, so that it
was not possible to imagine that the polar current could break through it.
As March is the coldest month of the year in the sea, we thought it
likely that the polar current in that month would be at its maximum,
and the Gulf Stream at its minimum, so that it was highly probable that
at no other period either, of the winter of 1896 — 97, had the polar current
forced its way into the North Sea.

Two series of deep-sea investigations right across the North At-
lantic, which Hjort had carried out on board the corvette Heimdal in
May, 1896 and 1897, were also of great interest, as they showed that
the relative volume of Arctic and Atlantic water was different at the
same period in difl'erent years. While the Gulf Stream in the middle of
May, 1896, was of great expanse and with a high surface-temperature
(above 90), in 1897 it was quite narrow, not much broader than in March of
the same year, and the thermometer did not rise above 7.8^ anywhere.

The continuation of the investigations was therefore a matter of
the greatest interest; but unfonunately no winter expedition could as yet
be sent out with this object, and recourse had to be had to the assistance
of captains of private steamers. Pettersson has given a preliminary account
[99,2] of two steamship routes across the North Atlantic in March, 1898.
One of these shows, that in about 6 5 ^ N. Lat. the Gulf Stream was
either very narrow, or overflowed by the fresher and colder polar water,
while both south and north of this, it was more expanded. Pettersson



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is of opinion that the polar current here has broken through, and that
earlier in the winter the point where it overflowed the Gulf Stream has
been situated farther south.

The Norwegian investigations directed by Dr, Hjort, obtained at
the same time observations on two steamer routes, S.S Westye Egeberg,
Capt. £. Tufte and S.S Heimdal, Capt. H, C. Hansen, The latter route
(Table 3) unfortunately went south of the Faroe Isles to the south of
Iceland, so far south that it did not touch the polar current. It is there-
fore of less importance to the solution of the question before us, and
moreover covers almost the same field in which observations are regu-
larly made by Danish observers all the year round.

The « Westye Egeberg's» route (Table 2), on the other hand, is from
the west coast of Norway straight up to Jan Mayen. The observations
give the same results as the line mentioned by Petlersson, namely that
in 65 ** N. Lat. the salinity diminishes to 34.80700, and the temperature
falls to 4 ^ C. There is thus undoubtedly an admixture of polar water
here. To the north and south, the surface-temperature exceeds S ^ C.
and the salinity is more than 35 7oo, thus showing that here the volumes
of the Gulf Stream flow in a fairly unmixed condition right up to the
surface. The c Westye Egeberg's* route lies a little to the east of Petters-
sons line, and that part of it in which the salinity is below 3 5 7oo, is a
little shorter than in Petterssons. It is, however, so long, that with
Petlersson I may assume that the layers of arctic admixture were here in a
line with the sea off the coast of Nordland, and that in 65 *^ N. Lat., the
surface of the Gulf Stream was broken into.

Petterssons supposition that the overflowed part lay farther south
earlier in the winter, so that it has been possible for arctic water to
enter the North Sea, is a hypothesis which still requires confirmation.

The results hitherto obtained show however with certainty, that
early in March, 1898, the Gulf Stream had its weakest point at a latitude
of about 65 ^ N.

This was also the case in March, 1897. The surface map (Hjort &
Gran [99] PL 3) and the tables (I.e. Tab. B IV a, b, pp. 13, 14) shew
that just about 64 and 65 *^ N. Lat. there was a slight decrease both in
temperature and salinity. The observations were rather too few to afibrd
certain proof that the polar current here communicated with the sea along
the Norwegian coast; but it is not impossible that a communication such



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as this also occurred in March, 1897. On the other hand, the same map
plainly shows, as we also pointed out, that the polar current does not
enter the North Sea, but rather forces the Atlantic water into it.

Even as late as May, in 1898, it may be seen that the Gulf Stream
has its narrowest point at about 65^ N. Lat.

The Norwegian investigations have obtained a great many obser-
vations through the kind assistance of two Tromsc captains, Capt. Fr,
Svendsen (S.S »Hvidfisken«) and Capt. /. Svetidscn (S.S »Jasai«), and from
the cruise of the corvette *Heimdal« in the Arctic Ocean, so that I have
been able to make a map of the surface for the month of May (PI. I).

Unfortunately there are no observations from the eastern part of
the North Atlantic, between 64^ and 71^ N. Lat., but it is nevertheless
sufficiently evident, that the water of the Gulf Stream, with its great
salinity, occupies a large portion of the surface of the northern part of the
North Atlantic, while in 64^ N. Lat. it is compressed into a narrower band.

The Heimdal's course is marked upon the map with a black line,
the stations of deep-sea soundings with small circles (cfr. Tab. 4, 5).

The observations in the northern part were taken on sealing expeditions;
and as sealers prefer to keep near the boundary between the Atlantic and
the Arctic waters, this part of the map is drawn from ver}- abundant data
(Tab. 6, 7).

The map shows that the curves of salinity and temperature do not
quite coincide. At 63 ^ and 64^ N. Lat. the 35 7oo salinity curve almost
coincides with the temperature-curve for 6 ® and at 72 ^ and 73 ^ with
the temperature-curve for 3 ® C.

The Heimdal's course from Bergen to the Arctic Ocean is of special
interest, because corresponding observations have been made at the same
time of year, for the two years preceding (Hjort & Gran [99] Tab. A III,
V and PI. IV), thus enabling a comparison to be made. The volume of the
Gulf Stream in May, 1898, had not nearly so great a superficial extent
as in 1896, but greater than in 1897. With regard to the temperature
also, 1898 stands between 1896 and 1897; in 1896 the highest surface-
temperature was 9.6 ^ in 1897, 7.8 ^ and in 1898, 8.3^. In 1898, the
Atlantic water went closer up to the Norwegian coast than in the two
preceding years, and it was found nearer the surface. During the latter
part of the cruise unfortunately, no deep-water investigations could be
made on account of stormy weather.



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In 1897, it appeared that the hydrographic conditions in this part
of the North Atlantic had altered little between the months of March
and May; the temperature had risen everywhere, but the salinity had
remained almost unchanged, so that the Heimdal's observation-line in
May might have been drawn on the surface map for March, without
essentially disturbing the saline curves. The case appears to be the same
in 1898, »Westye Egeberg*s« line for the month of March agrees very
well with the map for May, in tracts where observations are to be had
for both months. Thus in the spring, from March to May, the Gulf
Stream has its narrowest point on the surface, at about 65^ N. Lat.

The abundance of observations recently published from the Danish
Ingolf Expedition, (Martin Knudsen [98]) shows, however, that the east
Icelandic polar current can also reach much farther towards the south-
east in the summer, than was formerly supposed. Even in the months
of July and August, 1896, water was found with a salinit}^ of less than
35 7oo in 63^ — 64^ N. Lat. quite as far to the east as north of the
Faroe Isles, probably still farther (1. c. PI. XXXII). This water had a
temperature of from 8" to 10® while the volume of the Gulf Stream
was above 1 1 ^ Both temperature and salinity thus indicate a connection
with the polar current. On a sketch-map that Pettersson made from the
results of the Ingolf Expedition, he has drawn the 3 5 7oo curve in such
a manner that in 65 ® N. Lat., it reaches farthest towards the east, up to
about 4^ W. Long. (Pettersson [99, i], p. 142, fig. i).

Similar conditions prevailed in the summers of 1 897 and 1 898. In
both these years, water-samples were collected and the surface-temperatures
taken by Capt. L. Tufte on his voyage home from the north of Iceland
to the North Sea. The results will be found on Tables 12 and 13, a
graphic representation being moreover given of them on PL II, figs. 1,2.
In 1897, water of undoubted arctic origin was found on the surface
as far south as 62^27' N. Lat., 3^18' W. Long.; and in 1898, as far
as 62^ J3' N. and 4^30' W. It thus seems as if the polar current in
|uly, 1897, had gone more to the east than in 1898. This is not decided,
however, as the route in 1898 lay a little more to the south than that
of 1897.

On the other hand, it is noticeable, that the temperature in 1898
is much lower than in 1897. The curve in 1898 for 7® extends down
to 63** 40' N. and 7® W., and along the entire route no temperature of



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— 8 —

more than 12® is found, until quite in the North Sea. In 1897, the
7® curve did not reach farther towards the south-east than to about 64^
30' N. and 80 W.

The observations of temperature and salinity instituted by Wandel
in 1897, on Icelandic and Greenland steamer routes, are, as a rule,
taken a little more to the south, and have thus rarely met the east
Icelandic polar current. These observations also show that the surface-
temperature in the southern part of the North Atlantic Ocean between
the Shetland Isles and the Faroe Isles, was about i ^ lower in July of
1898, than in that of 1897. In 1897 it was 12 or 13^ C, in 1898
10.5 <» or ii.s" C. (Wandel & Ostenfeld [98], PI. I, Martin Knudsm &
Ostenfeld [99) PI II).

Thus in July, the polar current both in 1897 and 1898, reached
farthest towards the east in from 63 to 65*^ N. Lat., as in 1896. This was
also the case in March and May, 1897 and 1898; in March, 1898, and
possibly in 1897, it reached so far that it overflowed the Oulf Stream for
a sliort distance in about 65*^ N. Lat. On the other hand, all observations
in winter and summer show a high salinity and temperature at the be-
ginning of the North Sea about the Shetland Isles. Here the Gulf Stream
with its great volumes of water, forces its way towards the north-east;
and it is hardly conceivable that the polar current would be able to break
its way across it into the North Sea.

According to observations hitherto made, it seems that the polar
current and the Gulf Stream meet in the summer, farther north. The
polar current moves in a south-easterly direction and the Gulf Stream
towards the north-east.

Little has been ascertained about the result of this collision; but we
know, that
(i) In the direction of the Gulf Stream a current continues towards

the north-east, of which the salinity is considerably less (35.0 — 35.3)

than that ot the Gulf Stream off the northern extremity of Scotland,

but which has nevertheless on the whole retained its Atlantic

character.
(2) The surface-currents along the coast of Norway generally flow towards

the N. and N. E.
(^) The surface-currents along the east coast of Scotland and England

flow in a southerly direction.



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(4) In the northern part of the North Sea there are always large volumes

of water, of which the salinity exceeds 35 o/q©, and which is therefore

water of Atlantic origin.

The direction of the Gulf Stream is thus almost exactly followed
by its continuance in the North Atlantic, and by the coast currents along
the north of Norway.

On the other hand, the direction of the current in the north-western
part of the North Sea, corresponds rather with that of the east Iceland
polar current.

It does not, however, follow that the water of the polar current
moves southwards, and that of the Gulf Stream in a north-easterly direction.

It is quite as likely that on meeting, the currents intermingle, so
that both the northward and southward ^flowing water will consist of both
Arctic and Atlantic water. Neither the Atlantic water covering the sur-
face of the North Atlantic, nor the waters of the northern part of the
North Sea have such a high salinity as the Gulf Stream to the west ot
Scotland. But as a rule, the saHnity in the northern part of the North
Sea is higher than in the Gulf Stream north of the Shetland Isles, e. g.
in March, 1897, ^s will be seen from our surface-map and the accompa-
nying tables (Hjort & Gran [99], PI. 3, and Tab. B III, IV).

This would therefore seem to indicate, that the Atlantic water
entering the North Sea, is more unadulterated than that which continues
northwards, or that the greater part of the east Icelandic polar current
must unite with the northern branch of the Gulf Stream, and move in
an easterly direction parallel with the coast of Norway. There are also
other circumstances which indicate this.

The direction of the polar current, as may be seen on Petferssan's
sketch-map, is straight towards Stadt. At this promontory, the Norwegian
coast turns towards the east, and the boundary between the west and
north of Norway is placed here. Biologically, too, Stadt forms a clearly
marked boundary'. Many northern organisms have their southern limit
just here, and southern organisms their northern limit. This is even
the case with plankton organisms. As I shall relate at greater length
in the next section, a community of coast plankton lives north of Stadt
in the months of March and April, which agrees species for species with


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