South-East Atlantic 2000

METEOR-Berichte 06-5 South-East Atlantic 2000

Cruise No. 48 6 July 2000 – 3 November 2000, Walvis Bay - Walvis Bay

Wolfgang Balzer, Jürgen Alheit, Kay-Christian Emeis, Hans Ulrich Lass, Michael Türkay Editorial Assistance: Frank Schmieder Fachbereich Geowissenschaften, Universität Bremen Kirsten Schäfer Leibniz-Institut für Meereswissenschaften, Kiel Leitstelle METEOR Institut für Meereskunde der Universität Hamburg 2006

Table of Contents Page Table of Contents, Part 1 (M48/1)

II

Table of Contents, Part 2 (M48/2)

III


IV


V


VI

Abstract

VII

Zusammenfassung

VII

Research Objectives

IX

Acknowledgements

XIV

METEOR-Berichte 06-5, Part 1 (M48/1)

1-1 to 1-38


2-1 to 2-42


3-1 to 3-40


4-1 to 4-41


5-1 to 5-44

I

Table of Contents, Part 1 (M48/1) Page 1.1 Participants M 46/1 ............................................................................................... 1-2 1.2 Research Program ................................................................................................ 1-3 1.3 Narrative of the Cruise .......................................................................................... 1-4 1.4 Preliminary Results ............................................................................................... 1-6 1.4.1 Sediment Parameters and Hydrographic Data ............................................ 1-6 1.4.2 Protozoology .............................................................................................. 1-10 1.4.3 Benthic Foraminifera ................................................................................. 1-13 1.4.4 Meiofauna .................................................................................................. 1-15 1.4.5 Macroinfauna Collected from Box Cores ................................................... 1-19 1.4.6 Macrofauna Represented in Sledge-Samples ........................................... 1-24 1.4.7 Mega-Epifauna .......................................................................................... 1-27 1.5 Ship’s Meteorological Station .............................................................................. 1-32 1.6 Station List M 48/1 .............................................................................................. 1-33 1.7 Acknowledgements ............................................................................................. 1-36 1.8 References ......................................................................................................... 1-37

II

METEOR-Berichte 06-5 South-East Atlantic 2000 Part 1 Cruise No. 48, Leg 1 6 July – 2 August 2000, Walvis Bay - Walvis Bay,

K. M. Türkay

METEOR-Berichte 06-5, Cruise 48, Leg 1, Walvis Bay – Walvis Bay, July 6 – August 2, 2000

1-1

1. Leg M48/1 Table of Contents Page 1.1 Participants M 46/1 ...............................................................................................................1-2 1.2 Research Program .................................................................................................................1-3 1.3 Narrative of the Cruise ..........................................................................................................1-4 1.4 Preliminary Results ...............................................................................................................1-6 1.4.1 Sediment Parameters and Hydrographic Data ............................................................1-6 1.4.2 Protozoology .............................................................................................................1-10 1.4.3 Benthic Foraminifera ................................................................................................1-13 1.4.4 Meiofauna .................................................................................................................1-15 1.4.5 Macroinfauna Collected from Box Cores .................................................................1-19 1.4.6 Macrofauna Represented in Sledge-Samples ............................................................1-24 1.4.7 Mega-Epifauna ..........................................................................................................1-27 1.5 Ship’s Meteorological Station .............................................................................................1-32 1.6 Station List M 48/1 ..............................................................................................................1-33 1.7 Acknowledgements .............................................................................................................1-36 1.8 References ...........................................................................................................................1-37


Tab. 1.5:

1 - 19

Stations of box corer (BC), multicorer (MUC) and numbers of subsamples.

Stations 324 325 330 331 341 342 346

BC 8

MUC 2-8

8 1, 2 10 1, 2 1-7

Subsamples 1 13 5 10 11 8 18

Tab. 1.6: Abundance (n), mean (m) and mean deviation (m*) of Turbellaria and Nemertini per 100cm² sediment surface.

Turbellaria:

1. 4. 5

Nemertini:

Station

n

m

324, 325

60

330, 331

m*

Station

n

m

m*

4,5 2,343

324, 325

13

1,6

0,781

65

4,3 2,667

330, 331

10

1,0

0,662

341, 342

52

2,7 2,249

341, 342

12

0,6

0,664

346

110

6,1 2,568

346

19

1,1

0,864

Macroinfauna Collected From Box Cores (D. Fiege, R. Barnich, F. J. Cristobo, B. Hilbig, T. Jellinek, I. Kröncke, U. Mühlenhardt-Siegel, G. Purschke, J. I. Saiz-Salinas, V. Urgorri)

Introduction & Methodology During METEOR cruise 48 leg 1, samples were taken from six working areas (Fig. 1: map) in the Angola Basin along a latitudinal gradient from 22° S to 16° S in depths below 5200 m. Analysis of these box core samples will provide data to address the following questions: structure of sediments, density and biomass of the infauna, species composition and turnover along latitudinal gradients. The USNEL box corer takes quantitative samples of the sea bottom with the organisms residing on top and within the substrate. The goal was to collect 8 box core samples at each working area in order to reach a representative overview of the species composition (Sanders, 1968). Five of the six areas were sampled with this gear (Tab. 1). Due to technical problems with a newly manufactured 0.25 m2 box corer (GKG), a smaller one (0.09 m2, KKG) had to be used while the large one was technically improved. The upper 10 cm of all samples were sieved through stacked 1 mm, 0.5 mm and 0.3 mm screens and preserved as 0.5 mm and 0.3 mm fractions. Where possible, samples from four box cores at each working area were fixed in 4% formalin in seawater for determination of biomass and subsequent quantitative taxonomic analysis. One of these boxes was divided into twenty-four subcores 10 x 10 cm (modified after Hessler & Jumars, 1974) in order to evaluate the impact of a more gentle sample processing method on the percentage of

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identifiable animals. Samples from three box cores at each working area were washed in fresh water and fixed in 70% Ethanol. The remaining GKG was divided into 4 equal subsamples, one of which was used for determination of TOC and sediment parameters (see Chapter 1. 4. 1: Sediment parameters and hydrographic data) and for sampling of protozoa of the sea bed (s. Chapter: Protozoa of the sea bed). The second subsample was completely sieved through 0.3 mm screens to extract recent and subfossil Ostracoda. The remaining 2 subsamples were treated as mentioned above and fixed in 4% formalin in seawater. Tab. 1. 7:

Box corer deployments

working area station no. 1

2 3 4 5 6

322 323 323 324 324 330 336 341 345

depth

gear

no. of deployments

5115 m 5115 m 5115 m 5448 m 5448 m 5424 m 5395 m 5420 m 5390 m

GKG GKG KKG KKG GKG GKG GKG GKG GKG

1 2 2 4 5 8 4 9 10

no. of successful deployments 0 0 0 3 4 8 1 5 7

Sorting, weighing and taxonomic analysis of samples will be done in the home laboratories. The alcohol-fixed specimens can potentially be used for genetic analysis, for example in the most abundant species the gene flow along the transect can be studied whereas single specimens can be used for phylogenetic analysis. Observations & Preliminary Results Sediment The sediment appeared to be almost pure clay. If present at all, the layer of organic fluff was very thin. An RPD layer was not observed. In contrast to the trawl where slag, pumice and anthropogenic debris was collected, no hard substrates were observed in any of the cores. Fauna 1. Polychaeta Due to the microscopic size of most deep-sea polychaetes, only a first impression can be given based on the examination of some samples aboard ship. Representatives of the following families were found: Ampharetidae, Chaetopteridae, Flabelligeridae, Onuphidae, Oweniidae, Scalibregmatidae, Serpulidae, Sphaerodoridae, Spionidae, Terebellidae and Trichobranchidae. Specimens of Capitellidae, Scalibregmatidae, and Trichobranchidae (Terebellides sp.) were surprisingly found in up to 30 cm sediment depth, thus questioning the hypothesis of macrofauna being restricted to the uppermost 10 cm. Consequently the deeper sediment was spot checked for burrows and other signs of bioturbation.


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The material collected by all other gear (epibenthic sledge, trawl and multicorer), like Ampharetidae, Amphinomidae, Capitellidae, Chaetopteridae, Chrysopetalidae (?Dysponetus sp.), Cirratulidae, Fauveliopsidae, Flabelligeridae, Glyceridae, Hesionidae, Lumbrineridae, Maldanidae, Nereididae, Onuphidae, Opheliidae, Oweniidae, Paraonidae, Phyllodocidae, Pilargidae, Polynoidae, Sabellidae, Sabellariidae, Serpulidae, Siboglinidae, Sphaerodoridae (Ephesiella sp.), Spionidae, Syllidae, and Terebellidae leads to the assumption that representatives of these families might also be found in the box core samples. In the plankton samples pelagic polychaete species of the families Alciopidae (Vanadis sp.), Phyllodocidae (Phalacrophorus sp.), and Typhloscolecidae (Travisiopsis sp.) were found. 2. Ostracoda Ostracods have beeen sampled from box cores as well as epibenthic sledge samples in order to obtain 1) both living and dead material and 2) to achieve an overview in faunal changes during time and space. As far as it can be said by now, no changes by any means could be observed, either laterally by looking at different samples along the cruise transect, or by searching the box core samples vertically. The small ostracod-faunas that could be isolated during the cruise seem to be unaltered. According to the nature of the sampling techniques, mostly taxa of the Podocopida have been found. Only one taxon of the Myodocopida – Bathyconchoecia sp. – and two taxa of the Cladocopa – Polycope ssp. – have been isolated, taxa that could have been expected in these depths. All the other taxa are members of several families of the Podocopida: Zabythocypris (1 species), Bairdia (1 species) [Bairdiidae]; Bythocypris (2 species), Argilloecia (1 species) [Bythocyprididae]; Krithe (2 species) [Krithidae]; Macrocypris (1 species) [Macrocyprididae]; Bradleya (1 species), Poseidonamicus (1 species) [Hemicytheridae]; Legitimocythere (1 species), Henryhowella (1 species) [Trachyleberididae] plus 2-3 other taxa of the Trachyleberididae that could not be identified yet. All elements can be regarded as typical for the deep sea except Bairdia, a generic taxon that is abundant in shallow warm waters but also known to depths of about 3.000 metres. 3. Porifera In spite of the fact that this group is typically associated to hard bottoms, the phylum Porifera is well represented in these soft bottoms. Surprisingly, we found here a particular diversity of small sponges well adapted to life within the sediment showing a great variability in shapes. As the identification of sponge species is based also on microscopical characters of the skeleton, only a first impression can be given based on the examination of external features of some specimens sorted aboard the ship from stations 324, 330 and 341. As far as it can be said by now, without a careful revision of the sponge literature from deep waters, these particular infaunal sponges have not yet been described. Therefore most of the species found during this cruise appear to be new to science. 4. Sipuncula The sipunculan fauna was poorly represented in the box core samples. A total of 4 species was found in working areas 4 and 5. It seems that all belong to the same Nephasoma species. In contrast with results from the trawl samples where sipunculans were more abundant, box core

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samples show remarkably low densities and a widely irregular distribution with extremely low biomass figures. 5. Mollusca: Solenogastres and Caudofoveata So far no members of the Solenogastres and Caudofoveata have been found in the box core samples during our preliminary visual inspection of the 1 mm fraction, but the possibility that some specimens will be found by careful sorting can not be ruled out. However, in some samples taken with the epibenthic sledge (stations 318, 320, 340 and 344) 11 specimens of Solenogastres and 6 specimens of Caudofoveata were collected. It is likely that the final number of specimens will increase proportionally. After a preliminary external examination, 1 species of Caudofoveata and several species of Solenogastres appear to be represented, pending a more detailed study of the internal structures. All other taxa not listed herein will be identified by specialists after sorting. Quantitative results Quantitative results on the macro- and megafaunal community structure in relation to environmental parameters are available in Kröncke & Türkay (2003).

1. 4. 6

Macrofauna Represented in Sledge-Samples (A. Brandt, N. Brenke, U. Mühlenhardt-Siegel, J. W. Wägele)

Introduction Species composition of abyssal deep-sea communities, their dependence of biotic and abiotic parameters, speciation processes and the regionalization of the fauna are poorly known in comparison with shelf and upper slope environments. The aim of the present study was to sample macrofauna using an epibenthic sledge at 6 areas along a transect of approximately 700 km in the abyssal Angola basin. The material will be used to analyze changes of species composition of the regional peracarid fauna (Crustacea, Malacostraca) along this transect, to describe the biogeography, origin and phylogenetic relationships to other Atlantic deep-sea habitats using phylogenetic-biogeographic methods. Systematic studies will be based on morphological and molecular data. Other taxa will be described by other systematists. Until now all studies of deep-sea biodiversity were based on few samples from the continental shelf, slope and adjacent deep-sea areas, wherefore estimations of biodiversity rely only on material from regions of untypical productivity. In the past, the abyssal plains of oligotrophic oceanic regions were only sampled erratically, and the fauna was described only partially. Techniques During DIVA 1 an epibenthic sledge (based on Brandt & Barthel 1995, Ophelia 43: 15-23; modified by N. Brenke; epinet and supranet with mesh-size of 0.3 mm) was employed at each station at depths between 5127 and 5455 meter (see station list and figure 1. 5).