5.1. Bird and Marnrnal Counts (H. Eicken and R. Gradinger)
In continuation of work conducted by Joiris and coworkers during the previous two legs of the ARK-VIII expedition of Polarstern, birds and marnrnals were counted during the cruise.
Two different approaches to counting were taken. Frorn August 2 to 26 and frorn September 30 to October 6, a total of 51 30-rninute observations was conducted from the ship's bridge up to three tirnes a day. In accordance with international guidelines, those birds entering into a 300-rn corridor to either side of the ship were counted. Notes were taken on whether birds followed, crossed or rested in the ship's path. Wherever possible, particulars such as the ratio between juveniles and adults were recorded as well.
The occurrence of marnrnals was noted independent of the distance to the ship.
Between August 27 and September 29 the extrernely low numbers of birds and mammals encountered justified a rnodified counting procedure. Thus, birds or marnmals observed during the ice watch conducted at two-hour-intervals while under Progress (effectively 10-rninute time intervals) were counted, as well as those observed during station work on the ice.
Table 5.1-1 indicates the number of birds of different species counted during the 30-rninute intervals. The latitudinal distribution of the total nurnber of birds counted during each observation is indicated in Figure 5.1-1 for the tracks going in and out of the ice. Clearly, the nurnber of birds drops off sharply on the entering the ice. At the sarne time, a shift in species cornposition can be observed, with Auks decreasing in numbers and Ivory Gulls (Pagophila eburnea) particularly abundant in the marginal ice zone. The trend exhibited towards higher latitudes is representative of all observations rnade during the rniddle part of the cruise. For the entire track covered within the closed pack ice between August 5 and September 29, a total of 90 birds had been observed, with Fulmar (Fulmarus glacialis),
Soecies Total Number Counted
Rissa tridactyla Kittiwake 493
Pagophila eburnea Ivory Gull 88
Larus sabini Sabine's Gull 2
Larus hyperboreus Glaucous Gull 3
Larus glaucoides Iceland Gull 3
Unident. Gull 15
Fulrnarus glacialis Fulmar 332
Stercorarius longicaudus Long-tailed Skua 16
Stercorarius pornarinus Pomarine Skua 15
Stercorarius skua Great Skua 5
Sterna paradisaea Arctic Tern 9
Uria aalge and Common Guillemot and
Uria lornvia Brünnich' Guillernot (total) 69
Alle alle Little Auk 54
Cepphus grylle Black Guillemot 44
Fratercula arctica Puffin 14
Alca torda Razorbill 4
unident. Auk 52
unident. Duck 2
Sylvia atricapilla Blackcap 1
Total 1221
Table 5.1-1: Total number of birds observed during 51 30-minute observations.
Transect l E Transect 2
70 75 80 85 90
Latitude, ON
Fig. 5.1-1: Total number of birds counted during 51 30-minute intervals entering the ice on August 4 (ice edge 1 on transect 1, cf. map of cruise track) and leaving it on September 30 (ice edge 2 on transect 2).
observations, rnany of which rnay represent duplicate countings due to birds polar bears (Ursus maritimus) was observed, with a sighting as far north as 88' 53' N, 144' 05' E.
5.2. Plankton (H. Eicken and R. Gradinger)
The large scale distribution of the high Arctic pico- and nanoplankton was studied using two approaches. First, the phytoplankton standing stock was continuously measured using a Turner Design fluororneter (equipped with a continuous flow cuvette), which was connected to the water purnping System of P o l a r s t e r n shown track a distinctly higher algal biomass was observed south of 86' N together with high cell counts of diatorns, while in the northern part up to the North Pole, the lower biomass was nearly entirely forrned by autotrophic pico- and nanoplankton. A cornparison of the diatorn species composition found in the ice and in the pelagial is needed to find out whether the diatorns originated frorn rnelting ice floes or if they grew in the water colurnn.
In combination with the continuous-flow fluorornetry and in continuation of a program conducted by Joiris and coworkers (Free University of Brussels, Belgiurn) during the previous two legs of the Polarstern ARK-VIII expedition to study the enrichment of pollutants within polar organisms, plankton was continuously concentrated frorn the surface water during the entire cruise. This was achieved by passing unfiltered seawater taken in at the ship's bow into a Separator. Every three to four days the residue which had accurnulated in the base retainer and the stack bowls was collected and kept frozen at -30' C for further analysis (approx. 20 sarnples). Sirnilarly, surface sediment accumulations were collected for pollutant analysis as well.
13000
diatom bloom
l
small
nanoflagellates
*
A20001
85 85.5 86 86.5 87 87,5 88 88.5 89 89,5 90
lat
Fig. 5.2-1: In situ chlorophyll fluorescence (Fl-rnin, relative units) rneasured during the period of September 4 through September 18, 1991.
5.3 Benthos (I. Kröncke
The rnain benthological subject was to quantitatively sarnple the rnacro- and rneiofauna along the continental slope and at topographic highs but especially in the deep basins of the high Arctic. Since this region has insufficiently been investigated until now we were interested in the structure and biornass distribution of the benthic cornmunities.
Another topic was to deterrnine how far Atlantic species have spread by subrnergence into the deep basins and the percentage of endernic species in the basins. The feeding structure of the cornmunities is another interest. As food is lirnited in the abyssal basins under the ice, the organisms rnight have developed special rnechanisrns to survive with a rninimurn of food.
Sampling
In total 49 stations covering Nansen Basin (8 ), Gakkel Ridge ( 7 ) , Arnundsen Basin (13), Lornonosov Ridge (10), Makarov Basin (2), Morris Jesup Rise (6) and Yerrnak Plateau (5) were sarnpled with a 0.25 rn* box core (Tab. 5.2-1). Macro-fauna sarnples were taken out of the box core with a subsarnpler of 0.02 rn2. Meio-fauna was sarnpled out of the box core using tube cores or separately with the rnulticorer (24 stations, Tab. 5.2-1). Sampling for pigrnents, ATP and biogeoche-
PS21 56
-
Svalbard Shelf G KG Macro, Meio, P, ATP, B, Smical analysis took part as well. The bacterial biomass was collected on 12 stations along the poleward transect (Tab. 5.2-1).
Preliminary ßesult
The macrofauna samples were partly sorted On board for 30 stations On the poleward transect. Table 5.2-2 gives a preliminary overview on the rnacrofauna distribution in the Arctic basins.
The Nansen and the Amundsen basins showed lowest species and individual numbers. Arnphipods were the dominant species. Bioturbation was negligible.
In the coarse sediments of the Gakkel Ridge the fauna was very poor, on two stations not any life at all was observed.
Area S / 0.02 m2 N / m 2 Taxonomic a r o u ~ s
Table 5.2-2: Mean species and individual numbers for the macrofauna sarnpled On 30 stations along the poleward transect. Samples from Morris Jesup Rise and Yermak Plateau have not been sorted so far.
Along a transect sampled from the Makarov Basin towards the Lomonosov Ridge a more diverse fauna was observed, even the abundance increased especially on shallower stations. Again the Amphipods were the dominant group, followed by Polychaetes and Sponges. Latter ones were found in very high abundance at one station (PS21 86) on the slope of the Lomonosov Ridge.
---
Table 5.2-1: Station list for biological samples from giant box core (GKG) and multicorer (MUC) and sub-samples taken per station (Macro = Macrofauna, Meio = Meiofauna, P = Pigments, ATP, B = Bacteria, S = Sediments).
from Nansen and Arnundsen basins seern to be of Atlantic origin, only few endernic species were found. For species frorn the Makarov Basin and the Lornonosov Ridge further identification has to be done.
Sarnples from the Morris Jesup Rise and the Yerrnak Plateau have not been soried yet. However, it can be said that the rnacrofauna was rnore diverse and abundant than in the deep basins. On the Yerrnak Plateau the bioturbation reached down as deep as to 30 crn.