ALBERT

Description: The first expedition planned for 1970 was conducted in the ocean area between the Iberian and West African coasts (north of 15 ° N and 30 ° W, see map). The first three sections of the expedition were devoted mainly to biological questions. The fourth and last cruise-section was concentrated on geological and geophysical problems relating to the exploration of the Iberian shelf and shelf margin. Since the activation of R.V. "Meteor" in 1964, biological work has predominantly centred round two questions: a) comparative studies on nutrient dynamics in poor and rich areas and b) communities in the open ocean and their diurnal periodic migrations. It was the purpose of the Canaries Basin expedition to supplement the data collected during previous research cruises, particularly the Atlantic Seamount cruises ("Meteor" cruise 8 and 9) in 1967 and the West African expedition ("Meteor" cruise 13) in 1968. Research work in the various disciplines of marine biology was carried out simultaneously with the collecting of chemical and physical data indispensable for the understanding of productivity, transport and decomposition of organic matter as well as affording an opportunity to observe biogenic sedimentation. In planning the cruise, special emphasis was laid on ensuring as close a coordination as possible between the individual working programmes; it was decided that of the vast number of problems presently confronting marine science, particularly in the biological field, only a few should be selected and these approached from diverse sides. Each cruise section was directed at one focal point, around which other investigations were grouped. Cruise section I. Nutrient dynamics in an upwelling water body off the West African coast. Cruise section II. Communities and environmental conditions in the region of the Great Meteor Seamount. Cruise section III. Metabolism and communities on the Iberian deep-sea bed. Cruise section IV. Testing of geophysical gear. Moreover, investigations on two important questions that for a considerable length of time have occupied the attention of planktologists and geologists at various German institutes covered several cruise sections: a) The structure of communities in the oceanic deep scattering layers and at the sea surface; an insight into the feeding migrations of these organisms is essential for an understanding of the vertical transport of organic matter in the open sea. b) The origin of sediments in the deep sea and on the Iberian shelf in relation to organic productivity and climatic and oceanographic fluctuations. The Canaries Basin expedition 1970 inaugurated the "Cooperative Investigations of the Northeastern Central Atlantic" (CINECA), a programme coordinated by the International Council for the Exploration of the Sea (ICES) on the recommendation of the FAO and IOC.

Description: The Persian Gulf situated in the arid climate region of the northern hemisphere shows special conditions in its hydrochemistry. The high evaporation, the lack of large rivers, and the exclusion of deep water from the Indian Ocean governs the nutrient cycle. At 95 stations in the deeper part of the Persian Gulf (Iran side), in the Strait of Hormuz, and in the Gulf of Oman determinations of dissolved oxygen, dissolved inorganic phosphate, silicate, and pH were carried out. The data are compiled in the data report (BRETTSCHNEIDER, GRASSHOFF, KOSKE & v. TREPKA 1970). The ammonia, nitrite and nitrate data from 30 stations are added to this report. On 4 selected transverse profiles for phosphate, and dissolved oxygen and on 1 length profile for phosphate, silicate, oxygen, and pH the distribution of these components is shown and the in- and outflow is characterized. It is also pointed out that the nutrients on their way into the Persian Gulf are diminished and that temporary replenishment supply from a layer of about 100 m depth in the Indian Ocean follows. On one horizontal map the phosphate distribution in the surface and 30 m layer gives reference to biological activity. One diagram where nitrogen components are plotted against phosphate shows that nitrate is a limiting factor for productivity. 02/P04-P and P04-P/S‰ diagrams enable the different waterbodies and mixed layers to be characterized.

Description: From 27 Janua1y to 23 June 1979 R. V. "Meteor" surveyed the central equatorial Atlantic on a section along 22° W from 3° N to 2° S. During the observation period, a hydrographic section down to 600 m was repeated ten times with a continuous "Howaldt-Bathysonde" CTD and a rosette sampler. The station distance was 10 to 15 nm. The water samples were used to recalibrate salinity and to determine oxygen, nutrients and chlorophyll a. An undulating CTD system ("Delphin") was towed on 11 sections. A profiling distance of one to two nautical miles and a profile depth of 90 m was obtained. Five current meter arrays were moored along 22° W between 3° N and 1° S from January to March 1979. In May and June two moorings were installed at 2° N and at the equator. On the buoys measurements of wind speed and direction were obtained. At 43 stations a wire-guided Aanderaa profiling current meter was successfully lowered. Drifting buoy experiments were repeated three times with clusters of 5 to 10 buoys. A fourth experiment took place in 1978 in the Gulf of Guinea. On the way from and to port XBT sections were carried out. The data sets obtained by these instruments are presented in this data report.

Description: The atmospheric space from 11° N to 5° S along the Somali-coast of East-Africa over the western part of the Arabian Sea has been investigated making use of the aerological measurements, gained during the International Indian Ocean Expedition (IIOE) 1964/65. On the basis of the analyses obtained, an attempt is made to compute a heat budget for this space. In particular the following components have been taken into account: the net-radiation flux in the atmosphere (GN), the turbulent flux of sensible heat (Qs) and of latent heat (QL) from ocean to the atmosphere above, the potential (P), the sensible (I) and the latent energy (E). The vertical velocity component (ω) has been carefully determined making use of the adiabatic method but considering nonadiabatic effects of various kind lateron. From the vertical divergence of the net-radiation flux the cooling by long wave radiation was computed. Maximum effect of this process was obtained in the monsoon inversion (-5.4°C/day). Above the tropical tropopause the atmosphere shows maximum warming of 1.8°C/day. The intensity of the turbulent flux of sensible and latent heat is mainly determined by the windfield and by the local differences in the watertemperature. Maximum values are for Qs = 12·10-4 cal cm2 sec-1 and for QL = 140·10-4 cal cm2 sec-1 (Bowen-ratio R = Qs/QL = 8.5%, mostly not more than 4-5%). The computation of the vertical velocity rests besides the thermodynamic method (adiabatic) on a consideration of various non-adiabatic effects such as radiation, flux of sensible and latent heat. The following distribution has been obtained: Below the monsoon inversion a rising motion (maximum -30·10-4 mb/sec ≈ +2.8 cm/sec) and above a sinking motion (maximum +20·10-4 mb/sec ≈ -3.4 cm/sec) upwards to the tropical tropopause (near 90 mb). Above the tropopause weak rising motion (-2·10-4 mb/sec ≈ +1.3 cm/sec) was obtained. An attempt to compute various terms (in total 7) of the heat budget equation shows, that horizontal advection of various energy forms are only of importance in the monsoon layer (below the inversion) and above the tropical tropopause. In all height-intervalls considered the vertical advektion of the energy forms is dominant. The results of the budget-computation are presented in graphical form.

Description: During the Atlantic Expedition 1965 (IQSY) with the research vessel "Meteor" an extensive aerological programme was performed in order to investigate the lower trade wind regime. In this study energy and mass transport in the atmospheric layer below the top of the trade inversion was estimated on the basis of 4 to 8 radiosonde and radar wind measurements. The experiment took place on an anchoring station at the intersection of the Equator and 30° W longitude from September 12 to October 11, 1965. With the aid of simple model assumptions a mean sinking rate through the inversion of 540 m/d was derived. This value is determined mainly by the net radiative cooling and the prerequisite of no heating due to condensation. From the temporal variations of the daily averages of the thermal energy content within the inversion layer and the height of its boundaries it seems to be evident that changes of a quasi-equilibrium of mean subsidence and turbulent mixing at the inversion base are compensated by vertical motions of the inversion. The effect of strong mixing at the inversion base is supported by the fact that remarkable turbulent upward transport of latent heat is required at this level.

Description: The records of the potential gradient over the ocean obtained during the Atlantic Expedition of the research vessel "Meteor" in 1965 show a strong fluctuation of the values. Their frequency behaviour has been investigated. First a separation of different types of fluctuation has been made with regard to visual impression. Then power spectra of selected records were calculated. They show a F-5/3-range (F = frequency) in the interval of periods between 0.2 and 10 minutes for the most frequent visual type. For longer periods the ascent becomes more flat. This result can be explained by the assumption that the fluctuations are effected by the convective vertical air exchange over the sea.

Description: Siliceous skeletons were investigated in two core profiles (9 cores ), one off Cap de Sines, Portugal and the other off Cap de Mazagan, Morocco. Total number of skeletons was determined per gram of dried sediment at different core depths of the fraction 〉 21 μ. Results are compared with a core profile from the Arabian Sea. Diatoms are of four roups: (A) marine-planktonic, (B) marine-benthic, (C) freshwater and (D) Tertiary species (Trinacria e. g.). Species from groups (B), (C) and (D) are redeposited in all cores taken at a water depth of greater than 100 m. Small numbers of Silicoflagellates and Radiolarians were found throughout the cores from the Ibero-Moroccan shelf. In the Arabian Sea core, Radiolarians were concentrated in distinct horizons in which Tertiary material was redeposited (40-50, 140-150, 250-260 cm). The number of siliceous skeletons per gram of dried sediment decreases more or less rapidly with increasing depth in all cores. Whereas about 2500 skeletons were found in sediments close to the surface, approximately 100 skeletons only were found in deeper (〉40 cm) layers. Deeper horizons with more than 100 specimens were interpreted as redeposited material. This sediment contained robust skeletons, resistant against dissolution, as well as benthic and Tertiary material. The decrease of siliceous skeletons relative to core depth depends upon the sedimentation rate. Where the sedimentation rate is high, the opal dissolution zone extends down to 30-60 cm, where the sedimentation rate is low, it is located at 10-30 cm. Below these depths opals disappears. These zones also have approximately the same age (4000 years) everywhere. Siliceous skeletons dissolve differentially, first the Silicoflagellates disappear, second the Diatoms, third the Radiolarians, and fourth the Sponge Spicules. Surface structure of skeletons from near the opal dissolution zones are similar to those of skeletons treated with NaOH. Tertiary diatoms ( Trinacria e. g.) and benthic diatoms (Campylodiscus e. g.) dissolve less rapidly than skeletons of modern planktonic diatoms (Coscinodiscus e. g.). The time control of the opal dissolution zones appeared rather independent of various oceanic influences. No evidence was found for effects from upwelling either off Portugal or off Morocco. No difference in dissolution rates was recorded between the abyssal plains lying off these two areas. Likewise, there was no change in solution rates from Pleistocene to Holocene within either one of the abyssal plains. The Mediterranean outflow, which is enriched in dissolved silica, apparently had 110 effect on dissolution rates of siliceous skeletons in the sediment.

Description: This is a report about a joint scientific venture of German and Norwegian Institutes in an area between φ = 66° 45' N and 68° 30' N and λ 10° E to 7° 30' W. The chief scientist's report gives an outline of the cruise. The preliminary contributions by the scientists deal with results of gravity at sea, magnetic and geothermic measurements, the seismic shooting, results of continuous seismic reflection work, some refraction seismic results and with the observations of the ship's weather station.

Description: Along the Sierra Leone continental shelf edge, bedded rocks, presumably mostly calcareous sandstone, calcarenites and siltstones form exposures up to 10 km long in water depths ranging from 80 to 110 m. These outcrops are found in a 6 km broad zone along the shelf edge; landward they get covered by recent shelf sands. Their apparent strike direction parallds the shelf edge indicating nearly horizontal bedding which locally is interrupted by faulting. On the middle shelf, a terrace is well developed at a water depth of 56 m. Ripples, megaripples, pockmarks 1-5 m in diameter, and canyon-heads form other significant features of the shelf.

Description: The sediments of a 10.67 m long piston core recovered from the Sierra Leone Rise ("Meteor" Core 13519) have been analysed for their paleomagnetic properties. Using detailed demagnetization techniques, the geomagnetic Brunhes/Matuyama boundary could be identified between 9.81 and 9.89 m sub-bottom. This is in excellent agreement with the oxygen isotope stratigraphy by SARNTHEIN et al., this volume. Down to this level, therefore, the average apparent accumulation rate amounts to 13.5 m/m.y. assuming an age of 0.73 m.y. for the reversal boundary (BERGGREN et al. 1983). A second transition in magnetization polarity was recognized between 10.51 and 10.54 m sub-bottom. According to its magnetic signature it was tentatively correlated to the beginning of the Jaramillo event (0.98 m.y.). This would imply that in the lowermost part of the core the apparent accumulation rate decreases to less than 20% of that found in the upper sequences. However, as obviously only a small portion of the Jaramillo event is recorded in the sediment column, a more plausible solution is to keep the overall sedimentation rate about constant by introducing a hiatus of some 2·105 years shortly after the lower Jaramillo/Matuyama reversal boundary. Alternative interpretations are also discussed.

Description: From a 10.7 m long gravity core from the Sierra Leone Rise (5° 39,5' N, 19° 51'W) a detailed oxygen and carbon isotope record of both planktonic and benthonic foraminifera species was obtained extending from the Recent to the Jaramillo event. The analysis yielded six major results. 1. Benthos oxygen isotopes varied by 1.8-2.2‰ from interglacial to glacial times and may indicate a synglacial cooling of North Atlantic Deep Water at 2800 m depth by 1-3° C. 2. Variable anomalies between the benthos and plankton δ18 O record indicate a cooling of sea-surface temperatures (SST) by up to 6° C during some glacial stages. 3. Southerly trade winds and equatorial upwelling may exert the primary control of SST variations, in particular of extreme values of cold and warm stages and of the abrupt character of climate transitions and their leads and lags, and finally, of variable sedimentation rates. 4. The benthos δ13C record correlates well with the flux and preservation of organic matter. 5. A new time scale, CARPOR, was established from the assumption that terrigenous sediment supply was ± constant but CaC03 varied considerably. When applied to the δ18O record, three major and numerous short-term variations of sedimentation rates (0.8 to 4.0 cm/kyr) can be distinguished. 6. The climatic record was modified by bioturbation much more strongly during cold than during warm stages.

Description: Planktonic foraminiferal tests of the spinose species Orbulina universa, of the non-spinose Globorotalia tumida-menardii complex, and of a mixed species assemblage (grain size fraction 200-400 μm) were isolated from Sierra Leone Rise core 13 519-2 and analyzed for free, total, and bound (by difference) amino acids to study the isoleucine epimerization mechanism in fossil foraminiferal tests and to define empirical calibration curves for dating deep-sea sediments over the past 900,000 years. Total isoleucine epimerization curves typically separate into three "linear" segments of decreasing apparent rates with increasing time and exhibit a pronounced "species effect". The degree of epimerization attained at time is considerably lower in 0. universa than in G. tumida-menardii while the mixed species results scatter between the limits delineated by the two monospecific curves. Total allo/iso ratios are closely related to the proportion of free to total isoleucine accumulating in the tests indicating that the rate of hydrolysis of matrix proteins and peptides controls the overall epimerization reaction. The results are consistent with experimental evidence (KRIAUSAKUL & M1TTERER 1978, 1980 a, b) whereupon isoleucine epimerizes at a rapid rate in terminal positions but at slow rates in interior positions as well as in the free state. Notwithstanding free isoleucine exhibits the highest degree of epimerization due to preferential hydrolysis of extensively epimerized terminal isoleucine. Species-specific hydrolysis and epimerization rates are maintained until about 50% of bound isoleucine have been hydrolyzed to the free state corresponding to a total allo/iso ratio of about 0.5. Remaining peptide units appear to be more resistent against hydrolysis and separate species then show the same apparent epimerization rate dominantly controlled by the slow conversion rate in the free state until equilibrium is achieved in Miocene samples under deep-ocean temperature conditions (KING & HARE 1972 a). The degree of epimerization attained at comparable time in separate species will, however, remain different due to different initial rates of hydrolysis. Selective leaching of free isoleucine from the tests results in a lowering of total allo/iso ratios and apparent rate constants when significant amounts have been generated by diagenetic hydrolysis. Comparison with results based on Pacific core V 28-238 (KING & NEVILLE 1977) indicates an inverse relationship between the intensity of surficial carbonate dissolution and post-depositional leaching. Tests deposited under less corrosive conditions (Atlantic core 13519-2) will more significantly deviate from a closed system during diagenesis than those deposited in more corrosive bottom waters (Pacific core V 28-238). Carbonate dissolution removes proteinaceous lamellae from more external shell structures, which otherwise - if preserved during deposition - will preferentially be subject to leaching of free amino acids during diagenesis. This effect may qualify the applicability of empirical epimerization calibration curves to different depositional environments although the general agreement of the epimerization curves obtained for both sites is promising for future research. Identical apparent epimerization rates in G. tumidamenardii tests younger than 120,000 years (when leaching is stiH insignificant) at both Atlantic and Pacific sites are not consistent with the presently different bottom water temperatures in these regions. It is concluded that glacial North Atlantic Deep Water was cooler than at the present at the Sierra Leone Rise.

Description: Eine neue Art der zentrale Diatomeengattung Thalassiosira wird aus dem Auftriebsgebiet vor Kap Blanc, Afrika, beschrieben. Die Art ist durch die Ausbildung von gallertigen Tuben charakterisiert, die sich zusammenlagern und Zellaggregate bilden. A new species of the centric diatom genus Thalassiosira is described from upwelling waters near Cap Blanc, Africa. The species is charcterised by living in gelatinous tubes which are packed together and form large aggregates.

Description: 1. The new species Umbellula thieli, found in the Horseshoe deep-sea basin near Madeira, has only one single, big autozooid (="polyp"). Thus the species represents the ultimate point of an evolutionary series in some Pennatularian groups, characterised by the reduction of the number of autozooids. - This sea-pen, even it is a colony of polyps, appears as a solitary organism. 2. During the intensive investigations with trawls, dredges and cameras no sea-pen was found on the plateau of the Josephine Seamount and the Great Meteor Seamount. Pennatularians seem to lack in these biotopes.

Description: During the German "Meteor"-Canaries-Basin-Expedition, 1970, a total of 1577 meso- and bathypelagical fishes were caught by means of the IKMT and the Agassiz-Trawl in stratified or oblique hauls on 18 stations (Fig. 1). Some few fishes were selected from catches with the Bongo-Net. Stratified hauls were only made on the first six IKMT-stations (1000-700, 700-400 and 400-0 m), using an exchanging-container-system. Since this proved not to work satisfactorily the method was abandoned in favour of oblique hauls from 1000, 700 or 650 m to the surface. The material splits up into 31 fish families, 72 genera and 134 species. Nearly one third (35%) of the total of fish is yielded by the large family of Myctophidae, which is followed by the Gonostomatidae (31%), the Sternoptychidae (15%) and the Chauliodontidae (8%). All the remaining 26 families are of minor importance and represented, in general, each by less than 0,5%. No species new to science were found, but several are first records for this area. Since the circumstances of catch (gear, duration and depths) on the single stations were distinct, considerations on the qualitative and quantitative composition of the pelagic fish population, as well as their vertical distribution within the investigated area, seem not to be admissible. Fot this reason, only an annotated check-list is given. A new genus of myctophid fishes, Paralampanyctus, is erected, comprising the Lampanyctus ater-lineatus-niger-complex which is clearly separated from the remaining Lampanyctus-species. Otoliths, valuable diagnostic characteristics, are figured from the majority of the fish species discussed.

Description: Two aphyonids were caught in 1968 by the R.V. "Meteor" off Southwest Europe. One specimen, a male, belongs to Meteoria erythrops of which only a female and a juvenile were known. The other is referred to Nybelinella erikssoni hitherto found at two localities, north of Madagascar and in the tropical Atlantic Ocean. Nybelinella nom. nov. is proposed as a substitute for the preoccupied Nybelinia.

Description: In the subtropical NE Atlantic 337 neuston samples had been collected simultaneously in the 0-10 cm surface layer and in the adjacent 10-25 or 38-53 cm strata with a modified DAVID neuston catamaran. At a permanent station additional vertical stepwise hauls had been made down to 200 m with a Helgoland Larvae Net with a changing bucket device. Invertebrate neuston and other plankton was analysed in order to taclde the following problems: horizontal and vertical micro- and macrostratification, diurnal vertical migration, abundance, and feeding of species and their ontogenetical stages. Three ecological groups are described: 1. euneuston, living permanently in the uppermost layer (0-10 cm) by day and night; 2. facultative neuston, migrating into the surface layer mainly at crepuscular time and at night, or during certain phases of its early life history; 3. pseudoneuston, inhabiting with its highest concentration deeper layers, and reaching the immediate surface by relatively few specimens. - Contrary to the Black and Caspian Seas, the surface layer of the subtropical NE Atlantic is poor in nutrition compared with deeper layers. In the surface layer the total amount of invertebrates was only half of that in the adjacent strata of 10-25 and 38-53 cm, whereas the average concentration of Zooplankton in the 0-30 m macrolayer was eight times higher than in the surface layer. During daytime, particularly at noon, the average number of the invertebrate neuston diminished to 25 specimens/100 m3, and macrophages, i.e. mainly carnivores, represented about 75% of all the specimens, giving evidence of extreme scarcity of food at the sea surface. - The existence of a neuston biocoenoses in the subtropical NE Atlantic is discussed. The increase of the total number of invertebrates in the surface layer during dim light and at night, caused by facultative and pseudoneuston species, has to be regarded as an exchange of food between two communities: the biocoenoses of euneuston und pleuston on one hand and that faunal association on the other hand which is living in other habitats than at the very surface. Because of biological reasons and of terminological considerations the uppermost 5 to 10 cm thick layer at the sea surface should be called "pleustal".

Description: 1. On the cruises 3 and 15 of R.V. "Meteor" 6 grab samples, and 6 hauls with the 6 m Agassiztrawl were taken and at 2 stations the deep sea camera was lowered. This material gave quantitative results on the meiofauna and minimum counts of the macrofauna. 2. The nematodes constitute nearly 95% of the meiofauna, the copepoda only 2%, With increasing sediment depth the density of animals decreases gradually. In the uppermost centimeter of sediment (layer A) 42.6% of the meiofauna are found while only 3.7% live in layer G (tab. 6). Meiofauna weight ranges from 0.6-5.7 mg/25 m2 sediment surface i.e. 0.24-2.8 g/m2. 3. Mean numbers of individuals (tab. 3) and weights (tab. 5 for nematodes) show standard errors of 20-30%. As an approximate average value for further considerations the weight of the meiofauna in the area was taken as 1 g/m2. 4. Quantitative information on the macrofauna is derived from the trawls and the photographs for the actinia Chitonanthus abyssorum only, which is found in the rate of 1 individual/36-72 m 2, but seems to be less abundant generally. 5. Animal density does not decrease steadily from nearshore to offshore biocoenoses, i.e. generally with increasing depth. The decrease is more pronounced for macro- than for meiofauna. For the deep sea the weight proportion of macrofauna : meiofauna is of the order of 1 : 1. 6. With the assumption, that adaptation of metabolism to deep sea conditions is similar in macro- and meiofauna total metabolism of invertebrates is ascribed to meiofauna to more than 80%. 7. The structure of the biocoenosis of the deep sea floor is characterized by the meiofauna living on and in the sediment and by the dominance of sediment feeders in the macrofauna. 8. Considering the large numbets and high partition rates of bacteria a comparative large part of the metabolism in the deep sea sediment must be ascribed to bacteria. This favours the hypothesis, that with increasing depth and decreasing addition of organic material to the sediment, the importance of meiofauna and microorganisms for total metabolism increases. 9. Considering the different modes of food transport to the deep sea environment, i.e. sinking of dead particles, transport by vertical migration of organisms, aggregation of organic particles, adsorption of dissoloved organic substance to inorganic particles, and heterotrophy, the sediment may be assumed to contain more food for invertebrates than the water above the bottom. 10. Suspensionfeeders of macrofauna are fixed to hard substrates in the sediment surface. Same of them are shown to bend themselves down to the bottom in underwater photographs. This suggests the idea that some deep sea suspension feeders partly depend on food from the sediment surface, on which they feed directly.

Description: The genus Desmopterus (Pseudothecosomata, Gastropoda) includes two species. They are D. papilio Chun 1889 and D. gardineri T esch 1910. Both are tropical species having widespread distribution between 40° N and 40° S. D. papilio is common in occurrence, but D. gardineri is very rare. The present study on Zooplankton collections of the International Indian Ocean Expedition (IIOE) reveals that D. papilio is abundant in the area off the Somali coast, Gulf of Aden, South Arabian coast, Gulf of Oman, West coast of Pakistan, South-West coast of India, northern and Western Bay of Bengal, Southern Andaman Sea and North-West Australian Sea. The highest abundance was noticed in the area off Cochin. D. gardineri is relatively common in the Bay of Bengal, equatorial Zone and North-West Australian Sea. The seasonal Variation in spatial abundance shows that D. papilio is distinctly more abundant during the period dominated by the North-East Monsoon in the North Indian Ocean. Along 110° E two maxima were found, one during April—August between 9° and 11° S and another during November—February between 17° and 23° S. D. gardineri occurs mainly between April and August. The distribution in relation to the thermocline shows that D. papilio is almost uniformly abundant above and below the thermocline during day and night. But D. gardineri was almost absent above the thermocline. Therefore the thermocline appears to be a barrier for the distribution of D. gardineri.

Description: 1. Morphological characters of Ellisella flagellum were studied. The population of the plateau of the Josephine Seamount was compared with that of the Great Meteor Seamount. 2. The calcareous spicules of the colonies occur in several types (Fig. 1). The spicules of the cortex are uniform in all colonies, those of the calyx wall show differences between colonies. 3. The percentage of each spicule type of the calyx wall varies from colony to colony (Figs. 2-3). The range of variation is large (Fig. 4). 4. Differences between the two populations: a) Size: The colonies are bigger on the plateau of Great Meteor Seamount than those of the Josephine Seamount. b) Coloration: About one fourth of the specimens from Josephine Seamount are orange-red, on Meteor Seamount all colonies are white. c) Spicules: The average percentage of some spicule types show significant differences (see Table 1). 5. These results point to the morphological differentiation of E. flagellum in its area, probably favoured by the isolation of the seamounts and of the isles. The two different populations are preliminarily considered as infraspecific forms without nomenclatural state.

Description: 1. The three species of the Gorgonarian family Ellisellidae occurring in the eastern North Atlantic and the Mediterranean are described and compared with similar western Atlantic forms. 2. Material examined: a) the Gorgonarians obtained during the cruises of R.V. "Meteor" (Octocorallia now in the Senckenberg Museum, Frankfurt am Main), b) the Gorgonarians of the museums in Amsterdam, Leiden, London, Monaco and Paris. These collections contain the original material of classical expeditions and of the chief works on the east Atlantic and Mediterranean Gorgonarian fauna (WRIGHT, STUDER, KÜKENTHAL, THOMSON, STIASNY). 3. Ellisella paraplexauroides is found only in the African shelf, Ellisella jlagellttm on the seamounts and near the islands, Nicella granifera in both regions. 4. Ellisella flagellum is the most frequent species of the big benthic forms living on the plateaus of the Great Meteor Seamount and the Josephine Seamount. 5. The three species are quite distinct in their morphological characters. For each of these three east Atlantic species there can be found a similar species in the west. The colonies are similar in form but differ slightly in the structure of spicules. Ellisella flagellum / E. barbadensis, Ellisella paraplexauroides/ E. elongata and Nicella granifera/ N. guadalupensis can be spoken of as east-west-atlantic pairs. (This does not exclude that there are probably morphologically similar species in the Indo-Pacific). 6. Bach species has several types of spicules. The percentage of each spicule type varies from colony to colony, at least in Ellisella flagellum and in Nicella granifera. 7. The population of Ellisella jlagellttm of the Josephine Seamount and that of the Great Meteor Seamount show differences in coloration, average size of the colonies and significant differences in the average percentage of some spicule types.