Description: Additional comments on appendicularians found in unsorted parts of catches from the Arabian Sea are given. They concern: (1) specific differences between very young specimens of Oikopleura cornutogastra and 0. fusiformis; (2) the inclusion of LOHMANN's species Oikopleura mediterranea in the genus Folia which now comprises two species, F. gracilis LOHMANN 1896 and 0. mediterranea (LOHMANN 1899 n. n.); (3) the body form of very young Stegosoma magnum; (4) the occurrence of Appendicularia sicula FOL 1874 and (5) that of Kowalweskia oceanica LOHMANN 1899 in the area.

Description: In 22 samples, 6 from the Josephine Bank and 16 from the Great Meteor Bank, 14 halacarid species were found and described. Halacarus spiniger n. sp., Copidognathus magniporus n. sp., Arbodeoporus lineatus n. sp., A. brevocularis n. sp., Coloboceras karamani n. sp., Scaptognathus minutus n. sp., and Atelopsalis newelli were hitherto unknown. Acaromantis squilla TROUESSART & NEUMANN and Atelopsalis tricuspis TROUESSART were redescribed. Four larvae, probably belonging to Copidognathus longipes BARTSCH, C. tricorneata (LOHMANN), Lohmannella falcata (HODGE), and Atelopsalis newelli n. sp. were described, two Scaptognathus larvae could not be identified. To date only three species, Copidognathus tricorneata, Lohmanella falcata, and Scaptognathus minutus, have been found on both seamounts.

Description: Surface-living plankton of the subtropical NE-Atlantic (from 22° to 33° N and 28° W to the African coast) has been collected in winter 1970. Near the coast additional deeper hauls down to 50 m have been made. A modified David-Neuston sampler with two nets (300 or 500 μ mesh size) and a modified Gulf V sampler ("Langhai") with 300 μ were used. This paper deals with the ichthyoplankton only. A total of 14863 fishes or fish larvae were caught. They belonged to 51 different taxa. Between the neritic area (reaching to 130 nautical miles from the coast) and the oceanic area, great differences in the composition of ichthyoplankton were observed. The 27 neritic neuston samples yielded 110 less than 35 of the 51 taxa, while the 32 oceanic neuston samples had but 22 taxa, where of only 6 had not been caught in the first section. The average concentration of 190 fishes in 100 m3 of water filtered in the former area was significantly higher than in the oceanic area (112 individuals in 100 m3). The higher number of species near the coast is due to the fact that besides young stages of bottom-living and neritic pelagic fishes, mesopelagic species were caught. The neritic area showed higher surface temperatures, which normally brings a higher number of species. The species composition was not distinctly different with the results obtained in other seasons, but the percentage and the length distribution varied. The reason seems to be that the spawning of many species took place in this season. Young larvae of Macrorhamphosus, Scombridae, Carangidae and Sparidae have been caught in higher numbers. The following ecological aspects were observed in a part of the material. The distribution of some fishes, e.g. Mugilidae, indicate a preference to surface temperatures higher than 19°C. Sparids probably have the same temperature range. A large number of the ichthyoplankton showed a preference to the immediate surface for certain hours or even the whole day. For these species the daily rhythm was noted and an ecological grouping of the groups "euneuston", "daytime facultative neuston", "nighttime facultative neuston" and "pseudoneuston" was made. The "euneuston" includes all stages of Scomberesox, Mugilidae, Sparidae and the juvenile Carangidae. The "daytime facultative neuston" includes the juveniles of Macrorhamphosus and Scombridae together with the larvae of Ceratoscopelus. "Nighttime facultative neuston" are the young larvae of Macrorhamphosus and several genera of adult Mytophidae. "Pseudoneuston" includes mainly larvae of mesopelagic species as well as the larvae of Scombridae. For some taxa, a change in behaviour is probable. So early larval stages of Macrorhamphosus (up to 3 mm) and small Belone belong to the "nighttime facultative neuston", while elder stages should be regarded as "daytime facultative neuston" or "euneuston" in Belone. A change probably occurs in Scombridae and Carangidae too. Corresponding with this behavioural change in Macrorhamphosus a change in pigmentation from brown-white to blue seems to appear. A similar change may be assumed for Scombridae and Carangidae, but was not found in Belone.

Description: This is an account of hydromedusae from the Red Sea and the Gulf of Aden. Only 12 hydromedusae were previously known from the Red Sea, 18 from the Gulf of Aden. About 500 plankton samples - from various expeditions and own collections near Eilat - were investigated. 76 species of hydromedusae were found, 72 from the Red Sea, 30 from the Gulf of Aden. Only 5 species in both the Red Sea (Zanclea costata, Aequorea aequorea, Liriope tetraphylla, Aglaura hemistoma and Rhopalonema funerarium) and the Golf of Aden (Bougainvillia fulva, Eutima modesta, Liriope tetraphylla, Aglaura hemistoma and Rhopalonema velatum) bad been found there by formet investigators. 10 species (Pachycordyle conica, Podocoryne meteoris, P. minima, Allorathkea ankeli, Bougainvillia muscoides, Thamnostoma eilatensis, Laodicea fertilis, Phialidium ambiguum, Eirene kambara, Helgicirrha schulzei) are recorded for the first time from the Indian Ocean. 6 different regions are distinguished in the area of investigation [Bay of Eilat (E); Gulf of Aqaba (A); northern Red Sea proper (S); Red Sea (R) without E, A, S, D; Dahlak Archipelago (D); Gulf of Aden (N)] and compared with regard to the hydromedusae fauna. There is an eightfold increase in the number of species from north to south. The diversity of Antho- and Leptomedusae increases towards the Dahlak Archipelago and decreases again towards the Gulf of Aden, whereas the Trachylina increase towards the Gulf of Aden with exception of the samples from the Dahlak Archipelago. Considering the distribution of the suborders, one finds the reduction of numbers in the Leptomedusae responsible for the low values of Hydroida in the Gulf of Aden. In the Trachylina both suborders - Trachymedusae and Narcomedusae - are equally responsible for the distribution pattern found. The Red Sca is considerably richer in species of hydromedusac than the eastern Mediterranean which is comparable only to the Gulf of Aqaba in respect of the poor number of species. The number of specimen per sample decreases from Eilat towards the northern part of the Red Sea proper and then varies about the average for all samples (26), with the exception of the Dahlak Archipelago, where great numbers of Liriope tetraphylla cause maximal density values. The pattern of distribution is dominated by the Trachylina, especially the Trachymedusae, Hydroida play the minor role. The most important Anthomedusae is Bougainvillia fulva which is responsible for the distribution pattem of Hydroida; within the Leptomedusae no single species is dominating. Aglaura hemistoma is the most abundant medusa, their numbers decrease markedly from north to south. Rhopalonema velatum has a maximum abundance in the northern part of the Red Sea and a minimum around the Dahlak Archipelago. Solmundella bitentaculata is responsible for the distribution pattern of Narcomedusae with two maxima in the Gulf of Aqaba and in the R-region. The remaining species increase in density from north to south, with exception of the somewhat lower values from the Dahlak Archipelago. Numbers of individuals seem to increase with water temperature in the Red Sea, number of species to decrease. With increasing salinity numbers of both species and specimens per sample decrease. Above 38‰ S all of these values are below the mean.

Description: Among a macrofauna (madreporaria, spongia) from the Great Meteor Bank two halacarid species were found, Agatte alberti (TROUESSART) and Copidognathus raekor n. sp. The male, female and protonymph of Copidognathus raekor are described.

Description: The zooplankton, collected in three microlayers with the use of a neuston catamaran during the cruise of R.V. "Meteor" in the subtropical Northeastern Atlantic Ocean in 1967 was studied with a view to the ecology of the calanoid copepod family Pontellidae and its position in the neuston association. The material comprises 8 species. Two of them, the abundant Pontella atlantica and Anomalocera patersoni may be used as indicator species for two different pontellid associations which were confined to special water types characterized by different ranges of surface temperatures. The biocoenotic structures in both of the species groups are to some extent - similar to those of the co-occurring communities of total invertebrate neuston. Because of this, pontellids are considered to be a useful help in studying principal changes in structures of zooplankton due to the hydrographic environment. All the pontellid species, their developmental as well as their mature stages, showed daily vertical migrations, but of different extent and distinctness. With the exception of Pontellina plumata their preference of the uppermost 10 centimeters, the "pleustal", was well-defined. Nevertheless, only Pontella atlantica can be considered an euneustonic form. There was little evidence that in the atea of investigations pontellids played a really important role in the zooneuston community; only in the oceanic part of the area, during the hours of strongest solar radiation around noon, they might perhaps gain some ecological importance as predators in the surface layer.

Description: With the increasing aging of an upwelling body of water, a pronounced rise in the saprophyte counts was found at first in the surface water and later also in the deeper zones. They increased, for example, at a depth of 15 meters, from 30-50 to 250 bacteria/ml, which represents a production of 4 X 10-3 mg bacterial C/m3 water. Different bacteria populations were included on the medium used for isolation, which was prepared with both sea-water and fresh water. On the former, which had relatively few species represented, the spectrum ranged from whitish to yellowish-white halophilic marine bacteria. On the tap water medium, however, dominated a spectrum of white or vividly pigmented bacteria, comprising many species, with maximal development in fresh water. It is supposed that bacteria of terrestrial origin are involved here, which are possibly carried to the sea by sand or dust storms. With regard to the colony forms, no difference between the bacteria populations within or without the upwelling water could be determined. The greatest bacterial infiltration of the sediment was found on the surface (between 16 X 103 and 80 X 103 bacteria/cm3). Already in the upper 2 cm, a strong reduction of the saprophyte count was determined, together with a relative increase of those bacteria which possess a greater range of ecological amplitude. The saprophyte counts on the sediment surface decreased with an increase of water depth. On 21 strains of bacteria isolated from the open waters, investigations were carried out on their morphological characteristics and the most important metabolic reactions.

Description: During the 19th cruise of the research vessel "Meteor" between Madeira and Lisbon 260 strains of aerobic heterotrophic bacteria have been isolated from sediment samples collected from different depths. These strains have been identified mainly as members of the genera Marinovibrio, Pseudomonas, and Bacillus. The majority of bacteria isolated from shallow areas (Josephine Seamount) were sea water media requiring Marinovibrio and Pseudomonas spp. but in sediment samples taken from depths exeeding 1000 m the probably terrestrial sporeforming Bacillus spp. predominated. Further investigations in the same region during the 23rd cruise of the "Meteor" demonstrated that about 30 to 50% of the sporeforming bacteria found in the sediment samples could be isolated from dormant spores in situ. The remaining more than 50% of sporeformers in the deep sea region examined are believed to be metabolic active cells.